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| United States Patent Application |
20180289900
|
| Kind Code
|
A1
|
|
Lanier, JR.; Gregory R.
; et al.
|
October 11, 2018
|
Infusion Pump Assembly
Abstract
A wearable infusion pump assembly. The wearable infusion pump assembly
includes a reservoir for receiving an infusible fluid and a fluid
delivery system configured to deliver the infusible fluid from the
reservoir to an external infusion set. The fluid delivery system includes
a controller, a pump assembly for extracting a quantity of infusible
fluid from the reservoir and providing the quantity of infusible fluid to
the external infusion set, the pump assembly comprising a pump plunger,
the pump plunger having distance of travel, the distance of travel having
a starting position and an ending position, at least one optical sensor
assembly for sensing the starting position and ending position of the
pump plunger distance of travel and sending sensor output to the
controller, and a first valve assembly configured to selectively isolate
the pump assembly from the reservoir, wherein the controller receives the
sensor output and determines the total displacement of the pump plunger.
| Inventors: |
Lanier, JR.; Gregory R.; (Merrimack, NH)
; Gray; Larry B.; (Merrimack, NH)
; Lanigan; Richard J.; (Concord, NH)
; Kamen; Dean; (Bedford, NH)
; Fichera; Stephen L.; (Salem, NH)
; Kerwin; John M.; (Manchester, NH)
|
| Applicant: | | Name | City | State | Country | Type |
DEKA Products Limited Partnership |
Manchester |
NH |
US | | |
|---|
| Family ID:
|
43780103
|
| Appl. No.:
|
16/003783
|
| Filed:
|
June 8, 2018 |
Related U.S. Patent Documents
| | | | |
|---|
|
| Application Number | Filing Date | Patent Number |
|---|
| | 14138535 | Dec 23, 2013 | 9993600 |
| | 16003783 | | |
| | 12981350 | Dec 29, 2010 | 8613724 |
| | 14138535 | | |
| | 61291641 | Dec 31, 2009 | |
| | 61291733 | Dec 31, 2009 | |
|
|
| Current U.S. Class: |
1/1 |
| Current CPC Class: |
A61M 5/158 20130101; A61M 2205/0266 20130101; Y02A 90/10 20180101; A61M 5/16881 20130101; A61M 2205/3306 20130101; A61M 2005/1587 20130101; A61M 2205/3569 20130101; A61M 5/14244 20130101; A61M 2205/273 20130101; A61M 5/14248 20130101; A61M 5/16831 20130101; A61M 2209/086 20130101; A61M 39/08 20130101; A61M 2205/3592 20130101; A61M 2005/14268 20130101; G16H 40/67 20180101; A61M 5/14224 20130101; A61M 5/36 20130101; A61M 5/14216 20130101; A61M 5/172 20130101; G16H 20/17 20180101 |
| International Class: |
A61M 5/36 20060101 A61M005/36; A61M 5/168 20060101 A61M005/168; A61M 5/172 20060101 A61M005/172; A61M 5/142 20060101 A61M005/142; A61M 5/158 20060101 A61M005/158 |
Claims
1. A wearable infusion pump assembly comprising: a reservoir for
receiving an infusible fluid; and a fluid delivery system configured to
deliver the infusible fluid from the reservoir to an external infusion
set, wherein the fluid delivery system comprising: a controller; a pump
assembly for extracting a quantity of infusible fluid from the reservoir
and providing the quantity of infusible fluid to the external infusion
set, the pump assembly comprising a pump plunger, the pump plunger having
distance of travel, the distance of travel having a starting position and
an ending position; at least one optical sensor assembly for sensing the
starting position and ending position of the pump plunger distance of
travel and sending sensor output to the controller; and a first valve
assembly configured to selectively isolate the pump assembly from the
reservoir, wherein the controller receives the sensor output and
determines the total displacement of the pump plunger.
2. The wearable infusion pump assembly of claim 1 further comprising
wherein the controller correlates the displacement of the pump plunger to
a volume of fluid delivered.
3. The wearable infusion pump assembly of claim 2 further comprising
wherein the controller, based on the volume of fluid delivered, commands
an actuator to actuate the pump plunger to a target position.
4. The wearable infusion pump assembly of claim 1 further comprising a
second valve assembly configured to selectively isolate the pump assembly
from the external infusion set.
5. The wearable infusion pump assembly of claim 4 further comprising at
least one optical sensor assembly for sensing the position of the second
valve assembly.
6. The wearable infusion pump assembly of claim 1 further comprising: a
disposable housing assembly including the reservoir and a first portion
of the fluid delivery system; and a reusable housing assembly including a
second portion of the fluid delivery system.
7. The wearable infusion pump assembly of claim 6 wherein a first portion
of the pump assembly is positioned within the disposable housing
assembly, and a second portion of the pump assembly is positioned within
the reusable housing assembly.
8. The wearable infusion pump assembly of claim 6 wherein a first portion
of the first valve assembly is positioned within the disposable housing
assembly, and a second portion of the first valve assembly is positioned
within the reusable housing assembly.
9. The wearable infusion pump assembly of claim 4 wherein a first portion
of the second valve assembly is positioned within the disposable housing
assembly, and a second portion of the second valve assembly is positioned
within the reusable housing assembly.
10. The wearable infusion pump assembly of claim 1 wherein the external
infusion set is a detachable external infusion set configured to
releasably engage the fluid delivery system.
11. A wearable infusion pump assembly comprising: a reservoir; and a
fluid delivery system configured to deliver an infusible fluid from the
reservoir to an external infusion set, wherein the fluid delivery system
comprising: a controller; a pump assembly for extracting a quantity of
the infusible fluid from the reservoir and providing the quantity of the
infusible fluid to the external infusion set, the pump assembly
comprising a pump plunger, the pump plunger having distance of travel,
the distance of travel having a starting position and an ending position;
at least one optical sensor assembly for sensing the starting position
and ending position of the pump plunger distance of travel and sending
sensor output to the controller; and a first valve assembly configured to
selectively isolate the pump assembly from the reservoir, wherein the
controller receives the sensor output and determines a total displacement
of the pump plunger.
12. The wearable infusion pump assembly of claim 11 wherein the
controller receives the sensor output and determines the total
displacement of the pump plunger.
13. The wearable infusion pump assembly of claim 11 further comprising
wherein the controller correlates the displacement of the pump plunger to
a volume of fluid delivered.
14. The wearable infusion pump assembly of claim 13 further comprising
wherein the controller, based on the volume of fluid delivered, commands
an actuator to actuate the pump plunger to a target position.
15. The wearable infusion pump assembly of claim 11 further comprising a
second valve assembly configured to selectively isolate the pump assembly
from the external infusion set.
16. The wearable infusion pump assembly of claim 15 further comprising at
least one optical sensor assembly for sensing the position of the second
valve assembly.
17. The wearable infusion pump assembly of claim 11 further comprising: a
disposable housing assembly including the reservoir and a first portion
of the fluid delivery system; and a reusable housing assembly including a
second portion of the fluid delivery system.
18. The wearable infusion pump assembly of claim 17 wherein a first
portion of the pump assembly is positioned within the disposable housing
assembly, and a second portion of the pump assembly is positioned within
the reusable housing assembly.
19. The wearable infusion pump assembly of claim 17 wherein a first
portion of the first valve assembly is positioned within the disposable
housing assembly, and a second portion of the first valve assembly is
positioned within the reusable housing assembly.
20. The wearable infusion pump assembly of claim 15 wherein a first
portion of the second valve assembly is positioned within the disposable
housing assembly, and a second portion of the second valve assembly is
positioned within the reusable housing assembly.
21. The wearable infusion pump assembly of claim 11 wherein the external
infusion set is a detachable external infusion set configured to
releasably engage the fluid delivery system.
Description
CROSS REFERENCE TO RELATED APPLICATION(S)
[0001] The present application is a Continuation Application of U.S.
patent application Ser. No. 14/138,535, filed Dec. 23, 2013 and entitled
Infusion Pump Assembly (Attorney Docket No. L60), now U.S. Pat. No.
9,993,600, issued Jun. 12, 2018, which is a Continuation Application of
U.S. patent application Ser. No. 12/981,350, filed Dec. 29, 2010 and
entitled Infusion Pump Assembly (Attorney Docket No. 140), now U.S. Pat.
No. 8,613,724, issued Dec. 24, 2013, which claims priority from U.S.
Provisional Patent Application Ser. No. 61/291,641, filed Dec. 31, 2009
and entitled Method and System for Start-Up Integrity Verification for a
Medical Device (Attorney Docket No. H60), and U.S. Provisional Patent
Application Ser. No. 61/291,733, filed Dec. 31, 2009 and entitled
Infusion Pump Apparatus, Method and System (Attorney Docket No. H62),
each of which is hereby incorporated herein by reference in their
entireties.
FIELD OF THE INVENTION
[0002] This application relates generally to fluid delivery systems, and
more particularly to infusion pump assemblies.
BACKGROUND
[0003] Many potentially valuable medicines or compounds, including
biologicals, are not orally active due to poor absorption, hepatic
metabolism or other pharmacokinetic factors. Additionally, some
therapeutic compounds, although they can be orally absorbed, are
sometimes required to be administered so often it is difficult for a
patient to maintain the desired schedule. In these cases, parenteral
delivery is often employed or could be employed.
[0004] Effective parenteral routes of drug delivery, as well as other
fluids and compounds, such as subcutaneous injection, intramuscular
injection, and intravenous (IV) administration include puncture of the
skin with a needle or stylet. Insulin is an example of a therapeutic
fluid that is self-injected by millions of diabetic patients. Users of
parenterally delivered drugs may benefit from a wearable device that
would automatically deliver needed drugs/compounds over a period of time.
[0005] To this end, there have been efforts to design portable and
wearable devices for the controlled release of therapeutics. Such devices
are known to have a reservoir such as a cartridge, syringe, or bag, and
to be electronically controlled. These devices suffer from a number of
drawbacks including the malfunction rate. Reducing the size, weight and
cost of these devices is also an ongoing challenge. Additionally, these
devices often apply to the skin and pose the challenge of frequent
re-location for application.
SUMMARY OF THE INVENTION
[0006] In accordance with first implementation, a wearable infusion pump
assembly is disclosed. The wearable infusion pump assembly includes a
reservoir for receiving an infusible fluid and a fluid delivery system
configured to deliver the infusible fluid from the reservoir to an
external infusion set. The fluid delivery system includes a controller, a
pump assembly for extracting a quantity of infusible fluid from the
reservoir and providing the quantity of infusible fluid to the external
infusion set, the pump assembly comprising a pump plunger, the pump
plunger having distance of travel, the distance of travel having a
starting position and an ending position, at least one optical sensor
assembly for sensing the starting position and ending position of the
pump plunger distance of travel and sending sensor output to the
controller, and a first valve assembly configured to selectively isolate
the pump assembly from the reservoir, wherein the controller receives the
sensor output and determines the total displacement of the pump plunger.
[0007] Some embodiments of this implementation may include one or more of
the following features. Wherein the wearable infusion pump assembly
includes wherein the controller correlates the displacement of the pump
plunger to a volume of fluid delivered. Wherein the wearable infusion
pump assembly includes wherein the controller, based on the volume of
fluid delivered, commands an actuator to actuate the pump plunger to a
target position. Wherein the wearable infusion pump assembly further
includes a second valve assembly configured to selectively isolate the
pump assembly from the external infusion set. Wherein the wearable
infusion pump assembly further includes at least one optical sensor
assembly for sensing the position of the second valve assembly. Wherein
the wearable infusion pump assembly further includes a disposable housing
assembly including the reservoir and a first portion of the fluid
delivery system, and a reusable housing assembly including a second
portion of the fluid delivery system. Wherein the wearable infusion pump
assembly includes wherein a first portion of the pump assembly is
positioned within the disposable housing assembly, and a second portion
of the pump assembly is positioned within the reusable housing assembly.
Wherein the wearable infusion pump assembly includes wherein a first
portion of the first valve assembly is positioned within the disposable
housing assembly, and a second portion of the first valve assembly is
positioned within the reusable housing assembly. Wherein the wearable
infusion pump assembly includes wherein a first portion of the second
valve assembly is positioned within the disposable housing assembly, and
a second portion of the second valve assembly is positioned within the
reusable housing assembly. Wherein the wearable infusion pump assembly
includes wherein the external infusion set is a detachable external
infusion set configured to releasably engage the fluid delivery system.
[0008] In accordance with first implementation, a disposable housing
assembly for an infusion pump assembly is disclosed. The disposable
housing assembly includes a reservoir portion fluidly connected to a
fluid path, the reservoir portion including a bubble trap wherein the
bubble trap prevents air from moving from the reservoir portion to the
fluid path. The bubble trap further includes an outlet portion and a
non-outlet portion, the non-outlet portion including a tapered portion
that tapers to a bottom portion, the tapered portion of the non-outlet
portion ending at the outlet portion. The bubble trap also includes
wherein the outlet portion including the bottom portion in communication
with an upward ramped portion in fluid communication with a reservoir
outlet, wherein the bottom portion configured whereby fluid congregates
in the bottom portion and the tapered portion configured whereby air
bubbles congregate in the tapered portion.
[0009] Some embodiments of this implementation may include one or more of
the following features. Wherein the disposable housing assembly further
includes a membrane assembly, the membrane assembly connected to the
reservoir wherein the membrane assembly forms a portion of the reservoir.
Wherein the disposable housing assembly further includes a septum
assembly, the septum assembly formed on the membrane assembly. Wherein
the disposable housing assembly further includes a septum assembly, the
septum assembly connected to the reservoir. Wherein the disposable
housing assembly further includes a vent, wherein the vent further
comprising a filter.
[0010] The details of one or more embodiments are set forth in the
accompanying drawings and the description below. Other features and
advantages will become apparent from the description, the drawings, and
the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a side view of an infusion pump assembly;
[0012] FIG. 2 is a perspective view of the infusion pump assembly of FIG.
1;
[0013] FIG. 3 is an exploded view of various components of the infusion
pump assembly of FIG. 1;
[0014] FIG. 4 is a cross-sectional view of the disposable housing assembly
of the infusion pump assembly of FIG. 1;
[0015] FIGS. 5A-5C are cross-sectional views of an embodiment of a septum
access assembly;
[0016] FIGS. 6A-6B are cross-sectional views of another embodiment of a
septum access assembly;
[0017] FIGS. 7A-7B are partial top views of another embodiment of a septum
access assembly;
[0018] FIGS. 8A-8B are cross-sectional views of another embodiment of a
septum access assembly;
[0019] FIG. 9 is a perspective view of the infusion pump assembly of FIG.
1 showing an external infusion set;
[0020] FIGS. 10A-10E depict a plurality of hook-and-loop fastener
configurations;
[0021] FIG. 11A is an isometric view of a remote control assembly and an
alternative embodiment of the infusion pump assembly of FIG. 1;
[0022] FIGS. 11B-11R depicts various views of high level schematics and
flow charts of the infusion pump assembly of FIG. 1;
[0023] FIGS. 12A-12F is a plurality of display screens rendered by the
remote control assembly of FIG. 11A;
[0024] FIG. 13 is an isometric view of an alternative embodiment of the
infusion pump assembly of FIG. 1;
[0025] FIG. 14 is an isometric view of the infusion pump assembly of FIG.
13;
[0026] FIG. 15 is an isometric view of the infusion pump assembly of FIG.
13;
[0027] FIG. 16 is an isometric view of an alternative embodiment of the
infusion pump assembly of FIG. 1;
[0028] FIG. 17 is an plan view of the infusion pump assembly of FIG. 16;
[0029] FIG. 18 is a plan view of the infusion pump assembly of FIG. 16;
[0030] FIG. 19A is an exploded view of various components of the infusion
pump assembly of FIG. 16;
[0031] FIG. 19B is an isometric view of a portion of the infusion pump
assembly of FIG. 16;
[0032] FIG. 20 is a cross-sectional view of the disposable housing
assembly of the infusion pump assembly of FIG. 16;
[0033] FIG. 21 is a diagrammatic view of a fluid path within the infusion
pump assembly of FIG. 16;
[0034] FIGS. 22A-22C are diagrammatic views of a fluid path within the
infusion pump assembly of FIG. 16;
[0035] FIG. 23 is an exploded view of various components of the infusion
pump assembly of FIG. 16;
[0036] FIG. 24 is a cutaway isometric view of a pump assembly of the
infusion pump assembly of FIG. 16;
[0037] FIGS. 25A-25D are other isometric views of the pump assembly of
FIG. 24;
[0038] FIG. 26A-26B are isometric views of a measurement valve assembly of
the infusion pump assembly of FIG. 16;
[0039] FIG. 27A-27B are side views of the measurement valve assembly of
FIGS. 26A-26B;
[0040] FIGS. 28A-28D are views of a measurement valve assembly of the
infusion pump assembly of FIG. 16;
[0041] FIG. 29 is an isometric view of an alternative embodiment of the
infusion pump assembly of FIG. 1;
[0042] FIG. 30 is an isometric view of an alternative embodiment of the
infusion pump assembly of FIG. 1;
[0043] FIG. 31 is another view of the alternative embodiment infusion pump
assembly of FIG. 9;
[0044] FIG. 32 is an exploded view of another embodiment of an infusion
pump assembly;
[0045] FIG. 33 is another exploded view of the infusion pump assembly of
FIG. 32;
[0046] FIGS. 34A-34B depict another embodiment of an infusion pump
assembly;
[0047] FIGS. 35A-35C are a top view, side view, and bottom view of a
reusable housing assembly of the infusion pump assembly of FIG. 32;
[0048] FIG. 36 is an exploded view of the reusable housing assembly of
FIGS. 35A-35C;
[0049] FIG. 37 is an exploded view of the reusable housing assembly of
FIGS. 35A-35C;
[0050] FIG. 38A is an exploded view of the reusable housing assembly of
FIGS. 35A-35C;
[0051] FIG. 38B-38D are top, side and bottom views of one embodiment of a
dust cover;
[0052] FIGS. 39A-39C are a top view, side view, and bottom view of an
electrical control assembly of the reusable housing assembly of FIGS.
35A-35C;
[0053] FIGS. 40A-40C are a top view, side view, and bottom view of a base
plate of the reusable housing assembly of FIGS. 35A-35C;
[0054] FIGS. 41A-41B are a perspective top view and a perspective bottom
view of the base plate of FIGS. 40A-40C;
[0055] FIGS. 42A-42C are a top view, side view, and bottom view of a base
plate of the reusable housing assembly of FIGS. 35A-35C;
[0056] FIGS. 43A-43B depict a mechanical control assembly of the reusable
housing assembly of FIGS. 35A-35C;
[0057] FIGS. 44A-44C depict the mechanical control assembly of the
reusable housing assembly of FIGS. 35A-35C;
[0058] FIGS. 45A-45B depict the pump plunger and reservoir valve of the
mechanical control assembly of the reusable housing assembly of FIGS.
35A-35C;
[0059] FIGS. 46A-46E depict various views of the plunger pump and
reservoir valve of the mechanical control assembly of the reusable
housing assembly of FIGS. 35A-35C;
[0060] FIGS. 47A-47B depict the measurement valve of the mechanical
control assembly of the reusable housing assembly of FIGS. 35A-35C;
[0061] FIG. 48 is an exploded view of the disposable housing assembly of
the infusion pump assembly of FIG. 32;
[0062] FIG. 49A is a plan view of the disposable housing assembly of FIG.
48;
[0063] FIG. 49B is a sectional view of the disposable housing assembly of
FIG. 49A taken along line B-B;
[0064] FIG. 49C is a sectional view of the disposable housing assembly of
FIG. 49A taken along line C-C;
[0065] FIGS. 50A-50C depict the base portion of the disposable housing
assembly of FIG. 48;
[0066] FIGS. 51A-51C depict the fluid pathway cover of the disposable
housing assembly of FIG. 48;
[0067] FIGS. 52A-52C depict the membrane assembly of the disposable
housing assembly of FIG. 48;
[0068] FIGS. 53A-53C depict the top portion of the disposable housing
assembly of FIG. 48;
[0069] FIGS. 54A-54C depict the valve membrane insert of the disposable
housing assembly of FIG. 48;
[0070] FIGS. 55A-55B depict the locking ring assembly of the infusion pump
assembly of FIG. 32;
[0071] FIG. 56A-56C depict the locking ring assembly of the infusion pump
assembly of FIG. 32;
[0072] FIGS. 57-58 is an isometric view of an infusion pump assembly and a
fill adapter;
[0073] FIGS. 59-64 are various views of the fill adapter of FIG. 57;
[0074] FIG. 65 is an isometric view of another embodiment of a fill
adapter;
[0075] FIGS. 66-67 depict an infusion pump assembly and another embodiment
of a fill adapter;
[0076] FIGS. 68-74 are various views of the fill adapter of FIG. 66;
[0077] FIGS. 75-80 depict various views of an embodiment of a battery
charger;
[0078] FIGS. 81-89B depict various embodiments of battery chargers/docking
stations;
[0079] FIGS. 90A-90C are various views of a volume sensor assembly
included within the infusion pump assembly of FIG. 1;
[0080] FIGS. 91A-91I are various views of a volume sensor assembly
included within the infusion pump assembly of FIG. 1;
[0081] FIGS. 92A-92I are various views of a volume sensor assembly
included within the infusion pump assembly of FIG. 1;
[0082] FIGS. 93A-93I are various views of a volume sensor assembly
included within the infusion pump assembly of FIG. 1;
[0083] FIGS. 94A-94F are various views of a volume sensor assembly
included within the infusion pump assembly of FIG. 1;
[0084] FIG. 95 is an exploded view of a volume sensor assembly included
within the infusion pump assembly of FIG. 1;
[0085] FIG. 96 is a diagrammatic view of a volume sensor assembly included
within the infusion pump assembly of FIG. 1;
[0086] FIG. 97 is a two-dimensional graph of a performance characteristic
of the volume sensor assembly of FIG. 96;
[0087] FIG. 98 is a two-dimensional graph of a performance characteristic
of the volume sensor assembly of FIG. 96;
[0088] FIG. 99 is a two-dimensional graph of a performance characteristic
of the volume sensor assembly of FIG. 96;
[0089] FIG. 100 is a diagrammatic view of a volume sensor assembly
included within the infusion pump assembly of FIG. 1;
[0090] FIG. 101 is a two-dimensional graph of a performance characteristic
of the volume sensor assembly of FIG. 100;
[0091] FIG. 102 is a two-dimensional graph of a performance characteristic
of the volume sensor assembly of FIG. 100;
[0092] FIG. 103 is a diagrammatic view of a volume sensor assembly
included within the infusion pump assembly of FIG. 1;
[0093] FIG. 104 is a two-dimensional graph of a performance characteristic
of a volume sensor assembly included within the infusion pump assembly of
FIG. 1;
[0094] FIG. 105 is a two-dimensional graph of a performance characteristic
of a volume sensor assembly included within the infusion pump assembly of
FIG. 1;
[0095] FIG. 106 is a two-dimensional graph of a performance characteristic
of a volume sensor assembly included within the infusion pump assembly of
FIG. 1;
[0096] FIG. 107 is a two-dimensional graph of a performance characteristic
of a volume sensor assembly included within the infusion pump assembly of
FIG. 1;
[0097] FIG. 108 is a two-dimensional graph of a performance characteristic
of a volume sensor assembly included within the infusion pump assembly of
FIG. 1;
[0098] FIG. 109 is a diagrammatic view of a control model for a volume
sensor assembly included within the infusion pump assembly of FIG. 1;
[0099] FIG. 110 is a diagrammatic view of an electrical control assembly
for the volume sensor assembly included within the infusion pump assembly
of FIG. 1;
[0100] FIG. 111 is a diagrammatic view of a volume controller for the
volume sensor assembly included within the infusion pump assembly of FIG.
1;
[0101] FIG. 112 is a diagrammatic view of a feed forward controller of the
volume controller of FIG. 111;
[0102] FIGS. 113-114 diagrammatically depicts an implementation of an SMA
controller of the volume controller of FIG. 111;
[0103] FIG. 114A-114B is an alternate implementation of an SMA controller;
[0104] FIG. 115 diagrammatically depicts a multi-processor control
configuration that may be included within the infusion pump assembly of
FIG. 1;
[0105] FIG. 116 is a diagrammatic view of a multi-processor control
configuration that may be included within the infusion pump assembly of
FIG. 1;
[0106] FIG. 117A-117B diagrammatically depicts multi-processor
functionality;
[0107] FIG. 118 diagrammatically depicts multi-processor functionality;
[0108] FIG. 119 diagrammatically depicts multi-processor functionality;
[0109] FIG. 120A graphically depicts various software layers;
[0110] FIGS. 120B-120C depict various state diagrams;
[0111] FIG. 120D graphically depicts device interaction;
[0112] FIG. 120E graphically depicts device interaction;
[0113] FIG. 121 diagrammatically depicts a volume sensor assembly included
within the infusion pump assembly of FIG. 1;
[0114] FIG. 122 diagrammatically depicts an inter-connection of the
various systems of the infusion pump assembly of FIG. 1;
[0115] FIG. 123 diagrammatically depicts basal-bolus infusion events;
[0116] FIG. 124 diagrammatically depicts basal-bolus infusion events;
[0117] FIG. 125A-125G depicts a hierarchal state machine;
[0118] FIG. 126A-126M depicts a hierarchal state machine;
[0119] FIG. 127 is an exemplary diagram of a split ring resonator antenna;
[0120] FIG. 128 is an exemplary diagram of a medical device configured to
utilize a split ring resonator antenna;
[0121] FIG. 129 is an exemplary diagram of a split ring resonator antenna
and transmission line from a medical infusion device;
[0122] FIG. 130 is a graph of the return loss of a split ring resonator
antenna prior to contact with human skin;
[0123] FIG. 130A is a graph of the return loss of a split ring resonator
antenna during contact with human skin;
[0124] FIG. 131 is an exemplary diagram of a split ring resonator antenna
integrated into a device which operates within close proximity to
dielectric material;
[0125] FIG. 132 is a diagram of the dimensions of the inner and outer
portion of the exemplary embodiment;
[0126] FIG. 133 is a graph of the return loss of a non-split ring
resonator antenna prior to contact with human skin;
[0127] FIG. 133A is a graph of the return loss of a non-split ring
resonator antenna during contact with human skin;
[0128] FIGS. 134A-134C shows a top, cross sectional, taken at cross
section "B", and isometric view of one embodiment of a top portion of a
disposable housing assembly;
[0129] FIGS. 135A-135B shows top and cross sectional views, taken at cross
section "B", of one embodiment of a top portion of a disposable housing
assembly;
[0130] FIG. 136 shows a partially exploded view of one embodiments of the
reusable housing assembly together with one embodiment of the disposable
housing assembly with icons;
[0131] FIG. 137 shows a cross sectional view taken along "A" showing the
reusable housing assembly orientated above the disposable housing
assembly in an unlocked orientation;
[0132] FIG. 138 shows a cross sectional view taken along "A" showing the
reusable housing assembly attached to the disposable housing assembly in
an unlocked position;
[0133] FIG. 139 shows a cross sectional view taken along "A" showing the
reusable housing assembly attached to the disposable housing assembly in
a locked position;
[0134] FIG. 140A shows an isometric view of one embodiment of the reusable
housing assembly and one embodiment of the dust cover;
[0135] FIG. 140B is a top view of one embodiment of the dust cover;
[0136] FIG. 140C is a cross sectional view taken at "C" as shown in FIG.
140B;
[0137] FIG. 140D is a cut-away cross-sectional view of section "D" as
shown in FIG. 140C;
[0138] FIG. 141A is a view of one embodiment of a disposable housing
assembly;
[0139] FIG. 141B is a magnified cut away view of FIG. 141A as indicated by
"B";
[0140] FIG. 142A is a top view of one embodiments of a disposable housing
assembly;
[0141] FIG. 142B is a magnified cut away view of FIG. 142A as indicated by
"B";
[0142] FIG. 142C is a magnified cut away view of FIG. 142A as indicated by
"C";
[0143] FIG. 143A is a top view of one embodiment of the disposable housing
assembly;
[0144] FIG. 143B is a cross sectional view of one embodiment of the
disposable housing assembly, taken at "B" as indicated on FIG. 143A;
[0145] FIG. 144A is an isometric view of one embodiment of the disposable
housing assembly;
[0146] FIG. 144B is a magnified cut away sectional view of section "B" as
indicated in FIG. 144A;
[0147] FIG. 144C is a top view of one embodiment of the disposable housing
assembly;
[0148] FIG. 144D is a magnified cut away sectional view of section "D" as
indicated in FIG. 144C;
[0149] FIG. 144E is an illustrated view of a cross section of the bubble
trap according to one embodiment;
[0150] FIG. 145 is a graph of delivery volume versus pump actuation time
for an embodiment of the pump system;
[0151] FIG. 146 is a graph of one embodiment of the optical sensor output
as a function of reflector distance;
[0152] FIG. 147 is an illustration of various locations of optical sensors
in one embodiment of an infusion pump assembly;
[0153] FIG. 148A-148B is an embodiment of an optical sensor assembly where
148B is a magnified section view according to section "B" in FIG. 148A;
[0154] FIG. 149A-149B is an embodiment of an optical sensor assembly where
149B is a magnified section view according to section "B" in FIG. 149A;
[0155] FIG. 150 is a schematic of one embodiment of the pump system;
[0156] FIG. 151 is a schematic of the pump plunger drive electronics
according to one embodiment;
[0157] FIG. 152 is a graph of pump plunger target position versus volume
delivered according to one embodiment;
[0158] FIG. 153 is a schematic of a model of the pump plunger as a gain
element with a dead band and saturation limit according to one
embodiment;
[0159] FIG. 154A is a schematic of the SMA power controller according to
one embodiment;
[0160] FIG. 154B is a graph of time versus pump plunger position according
to one embodiment;
[0161] FIG. 154C is a graph of time versus duty cycle according to one
embodiment;
[0162] FIG. 155 is a schematic representation of sampling time;
[0163] FIG. 156 is a graph of time versus pump plunger position according
to one embodiment;
[0164] FIG. 157 is a graph of time versus measurement valve position
according to one embodiment;
[0165] FIG. 158 is a schematic SMA switch monitoring according to one
embodiment;
[0166] FIG. 159A is a graph of delivery number versus position according
to one embodiment;
[0167] FIG. 159B is a graph of delivery number versus trajectory error
according to one embodiment;
[0168] FIG. 160 is a flow chart of the delivery controller according to
one embodiment;
[0169] FIG. 161 is a flow chart of the inner voltage and outer volume
feedback controller according to one embodiment;
[0170] FIG. 162 is a flow chart of the volume controller architecture
according to one embodiment;
[0171] FIG. 163 is a flow chart of one embodiment of the volume delivery
controller feed-forward;
[0172] FIG. 164 is a flow chart of one embodiment of the discontinuous
leak check;
[0173] FIG. 165 is a flow chart of one embodiment of at least a portion of
a start-up integrity test;
[0174] FIG. 166 is a flow chart of one embodiment of at least a portion of
a start-up integrity test;
[0175] FIG. 167 is a flow chart of one embodiment of at least a portion of
a start-up integrity test;
[0176] FIG. 168 is a graph of the pump plunger target position versus the
volume delivered according to one embodiment;
[0177] FIG. 169 is a graph of valve position versus the volume pumped
according to one embodiment;
[0178] FIG. 170 is a graph of a pump plunger target position versus the
volume delivered according to one embodiment;
[0179] FIG. 171 is a flow chart of the volume controller architecture
according to one embodiment; and
[0180] FIG. 172 is a flow chart of the inner voltage and outer volume
feedback controller according to one embodiment.
[0181] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0182] Referring to FIGS. 1-3, an infusion pump assembly 100 may include a
reusable housing assembly 102. Reusable housing assembly 102 may be
constructed from any suitable material, such as a hard or rigid plastic,
that will resist compression. For example, use of durable materials and
parts may improve quality and reduce costs by providing a reusable
portion that lasts longer and is more durable, providing greater
protection to components disposed therein.
[0183] Reusable housing assembly 102 may include mechanical control
assembly 104 having a pump assembly 106 and at least one valve assembly
108. Reusable housing assembly 102 may also include electrical control
assembly 110 configured to provide one or more control signals to
mechanical control assembly 104 and effectuate the basal and/or bolus
delivery of an infusible fluid to a user. Disposable housing assembly 114
may include valve assembly 108 which may be configured to control the
flow of the infusible fluid through a fluid path. Reusable housing
assembly 102 may also include pump assembly 106 which may be configured
to pump the infusible fluid from the fluid path to the user.
[0184] Electrical control assembly 110 may monitor and control the amount
of infusible fluid that has been and/or is being pumped. For example,
electrical control assembly 110 may receive signals from volume sensor
assembly 148 and calculate the amount of infusible fluid that has just
been dispensed and determine, based upon the dosage required by the user,
whether enough infusible fluid has been dispensed. If enough infusible
fluid has not been dispensed, electrical control assembly 110 may
determine that more infusible fluid should be pumped. Electrical control
assembly 110 may provide the appropriate signal to mechanical control
assembly 104 so that any additional necessary dosage may be pumped or
electrical control assembly 110 may provide the appropriate signal to
mechanical control assembly 104 so that the additional dosage may be
dispensed with the next dosage. Alternatively, if too much infusible
fluid has been dispensed, electrical control assembly 110 may provide the
appropriate signal to mechanical control assembly 104 so that less
infusible fluid may be dispensed in the next dosage.
[0185] Mechanical control assembly 104 may include at least one
shape-memory actuator 112. Pump assembly 106 and/or valve assembly 108 of
mechanical control assembly 104 may be actuated by at least one
shape-memory actuator, e.g., shape-memory actuator 112, which may be a
shape-memory wire in wire or spring configuration. Shape memory actuator
112 may be operably connected to and activated by electrical control
assembly 110, which may control the timing and the amount of heat and/or
electrical energy used to actuate mechanical control assembly 104. Shape
memory actuator 112 may be, for example, a conductive shape-memory alloy
wire that changes shape with temperature. The temperature of shape-memory
actuator 112 may be changed with a heater, or more conveniently, by
application of electrical energy. Shape memory actuator 112 may be a
shape memory wire constructed of nickel/titanium alloy, such as
NITINOL.TM. or FLEXINOL.RTM..
[0186] Infusion pump assembly 100 may include a volume sensor assembly 148
configured to monitor the amount of fluid infused by infusion pump
assembly 100. For example, volume sensor assembly 148 may employ, for
example, acoustic volume sensing. Acoustic volume measurement technology
is the subject of U.S. Pat. Nos. 5,575,310 and 5,755,683 assigned to DEKA
Products Limited Partnership, as well as U.S. patent application
Publication Nos. US 2007/0228071 A1, US 2007/0219496 A1, US 2007/0219480
A1, US 2007/0219597 A1, the entire disclosures of all of which are
incorporated herein by reference. Other alternative techniques for
measuring fluid flow may also be used; for example, Doppler-based
methods; the use of Hall-effect sensors in combination with a vane or
flapper valve; the use of a strain beam (for example, related to a
flexible member over a fluid reservoir to sense deflection of the
flexible member); the use of capacitive sensing with plates; or thermal
time of flight methods. One such alternative technique is disclosed in
U.S. patent application Ser. No. 11/704,899 filed Feb. 9, 2007, now U.S.
Publication No. US-2007-0228071-A1 published Oct. 4, 2007 and entitled
Fluid Delivery Systems and Methods (Attorney Docket No. E70), the entire
disclosure of which is incorporated herein by reference. Infusion pump
assembly 100 may be configured so that the volume measurements produced
by volume sensor assembly 148 may be used to control, through a feedback
loop, the amount of infusible fluid that is infused into the user.
[0187] Infusion pump assembly 100 may further include a disposable housing
assembly 114. For example, disposable housing assembly 114 may be
configured for a single use or for use for a specified period of time,
e.g., three days or any other amount of time. Disposable housing assembly
114 may be configured such that any components in infusion pump assembly
100 that come in contact with the infusible fluid are disposed on and/or
within disposable housing assembly 114. For example, a fluid path or
channel including a reservoir, may be positioned within disposable
housing assembly 114 and may be configured for a single use or for a
specified number of uses before disposal. The disposable nature of
disposable housing assembly 114 may improve sanitation of infusion pump
assembly 100.
[0188] Referring also to FIG. 4, disposable housing assembly 114 may be
configured to releasably engage reusable housing assembly 102, and
includes a cavity 116 that has a reservoir 118 for receiving an infusible
fluid (not shown), e.g., insulin. Such releasable engagement may be
accomplished by a screw-on, a twist-lock or a compression fit
configuration, for example. Disposable housing assembly 114 and/or
reusable housing assembly 102 may include an alignment assembly
configured to assist in aligning disposable housing assembly 114 and
reusable housing assembly 102 for engagement in a specific orientation.
Similarly, base nub 120 and top nub 122 may be used as indicators of
alignment and complete engagement.
[0189] Cavity 116 may be at least partially formed by and integral to
disposable housing assembly 114. Cavity 116 may include a membrane
assembly 124 for at least partially defining reservoir 118. Reservoir 118
may be further defined by disposable housing assembly 114, e.g., by a
recess 126 formed in base portion 128 of disposable housing assembly 114.
For example, membrane assembly 124 may be disposed over recess 126 and
attached to base portion 128, thereby forming reservoir 118. Membrane
assembly 124 may be attached to base portion 128 by conventional means,
such as gluing, heat sealing, and/or compression fitting, such that a
seal 130 is formed between membrane assembly 124 and base portion 128.
Membrane assembly 124 may be flexible and the space formed between
membrane assembly 124 and recess 126 in base portion 128 may define
reservoir 118. Reservoir 118 may be non-pressurized and in fluid
communication with a fluid path (not shown). Membrane assembly 124 may be
at least partially collapsible and cavity 116 may include a vent
assembly, thereby advantageously preventing the buildup of a vacuum in
reservoir 118 as the infusible fluid is delivered from reservoir 118 to
the fluid path. In a preferred embodiment, membrane assembly 124 is fully
collapsible, thus allowing for the complete delivery of the infusible
fluid. Cavity 116 may be configured to provide sufficient space to ensure
there is always some air space even when reservoir 118 is filled with
infusible fluid.
[0190] The membranes and reservoirs described herein may be made from
materials including but not limited to silicone, NITRILE, butyl rubber,
SANTOPRENE, thermal plastic elastomers (TPE), styrene ethylene butylene
styrene (SEBS) and/or any other material having desired resilience and
properties for functioning as described herein. Additionally, other
structures could serve the same purpose.
[0191] The use of a partially collapsible non pressurized reservoir may
advantageously prevent the buildup of air in the reservoir as the fluid
in the reservoir is depleted. Air buildup in a vented reservoir could
prevent fluid egress from the reservoir, especially if the system is
tilted so that an air pocket intervenes between the fluid contained in
the reservoir and the septum of the reservoir. Tilting of the system is
expected during normal operation as a wearable device.
[0192] Reservoir 118 may be conveniently sized to hold an insulin supply
sufficient for delivery over one or more days. For example, reservoir 118
may hold about 1.00 to 3.00 ml of insulin. A 3.00 ml insulin reservoir
may correspond to approximately a three day supply for about 90% of
potential users. In other embodiments, reservoir 118 may be any size or
shape and may be adapted to hold any amount of insulin or other infusible
fluid. In some embodiments, the size and shape of cavity 116 and
reservoir 118 is related to the type of infusible fluid that cavity 116
and reservoir 118 are adapted to hold.
[0193] Disposable housing assembly 114 may include a support member 132
(FIG. 3) configured to prevent accidental compression of reservoir 118.
Compression of reservoir 118 may result in an unintentional dosage of
infusible fluid being forced through the fluid path to the user. In a
preferred embodiment, reusable housing assembly 102 and disposable
housing assembly 114 may be constructed of a rigid material that is not
easily compressible. However, as an added precaution, support member 132
may be included within disposable housing assembly 114 to prevent
compression of infusion pump assembly 100 and cavity 116 therein. Support
member 132 may be a rigid projection from base portion 128. For example,
support member 132 may be disposed within cavity 116 and may prevent
compression of reservoir 118.
[0194] As discussed above, cavity 116 may be configured to provide
sufficient space to ensure there is always some air space even when
reservoir 118 is filled with infusible fluid. Accordingly, in the event
that infusion pump assembly 100 is accidentally compressed, the infusible
fluid may not be forced through cannula assembly 136 (e.g., shown in FIG.
9).
[0195] Cavity 116 may include a septum assembly 146 (FIG. 3) configured to
allow reservoir 118 to be filled with the infusible fluid. Septum
assembly 146 may be a conventional septum made from rubber or plastic and
have a one-way fluid valve configured to allow a user to fill reservoir
118 from a syringe or other filling device. In some embodiments, septum
146 may be located on the top of membrane assembly 124. In these
embodiments, cavity 116 may include a support structure (e.g., support
member 132 in FIG. 3) for supporting the area about the back side of the
septum so as to maintain the integrity of the septum seal when a needle
is introducing infusible fluid into cavity 116. The support structure may
be configured to support the septum while still allowing the introduction
of the needle for introducing infusible fluid into cavity 116.
[0196] Referring also to FIGS. 134A-135B, embodiments of a top portion
2962 of the disposable housing assembly are shown. Top portion 2962 is
shown in FIG. 134A, with the cross sectional view, taken at "B", shown in
FIG. 134B. Septum assembly 2964 is shown. In some embodiments, the septum
assembly 2964 includes a tunnel feature which may, in some embodiments,
serves as a feature to press a needle (e.g., filling needle) against
while not pressing full force directly onto the septum 2966. In some
embodiments, as shown in FIGS. 134A-134C, the septum 2966 may be a
separately molded part attached to the disposable housing assembly
portion 2962, but separate from the membrane assembly 902.
[0197] Referring now to FIGS. 135A-135C, another embodiment of a septum
assembly 2968, part of a top portion 2962 of the disposable housing
assembly is shown. In this embodiment, the septum 2970 may be molded into
the membrane assembly 902.
[0198] In some embodiments of the various embodiments of the septum
assembly 2964, 2968, the septum 2970, 2976 may be at a forty-five degree
angle relative to the top portion 2962. In some embodiments, the septum
2970, 2976 may be made from the same material as the membrane assembly
902.
[0199] Infusion pump assembly 100 may include an overfill prevention
assembly (not shown) that may e.g., protrude into cavity 116 and may
e.g., prevent the overfilling of reservoir 118.
[0200] In some embodiments, reservoir 118 may be configured to be filled a
plurality of times. For example, reservoir 118 may be refillable through
septum assembly 146. As infusible fluid may be dispensed to a user,
electronic control assembly 110 may monitor the fluid level of the
infusible fluid in reservoir 118. When the fluid level reaches a low
point, electronic control assembly 110 may provide a signal, such as a
light or a vibration, to the user that reservoir 118 needs to be
refilled. A syringe, or other filling device, may be used to fill
reservoir 118 through septum 146.
[0201] Reservoir 118 may be configured to be filled a single time. For
example, a refill prevention assembly (not shown) may be utilized to
prevent the refilling of reservoir 118, such that disposable housing
assembly 114 may only be used once. The refill prevention assembly (not
shown) may be a mechanical device or an electro-mechanical device. For
example, insertion of a syringe into septum assembly 146 for filling
reservoir 118 may trigger a shutter to close over septum 146 after a
single filling, thus preventing future access to septum 146. Similarly, a
sensor may indicate to electronic control assembly 110 that reservoir 118
has been filled once and may trigger a shutter to close over septum 146
after a single filling, thus preventing future access to septum 146.
Other means of preventing refilling may be utilized and are considered to
be within the scope of this disclosure.
[0202] As discussed above, disposable housing assembly 114 may include
septum assembly 146 that may be configured to allow reservoir 118 to be
filled with the infusible fluid. Septum assembly 146 may be a
conventional septum made from rubber or any other material that may
function as a septum, or, in other embodiments, septum assembly 146 may
be, but is not limited to, a plastic, or other material, one-way fluid
valve. In various embodiments, including the exemplary embodiment, septum
assembly 146 is configured to allow a user to fill reservoir 118 from a
syringe or other filling device. Disposable housing assembly 114 may
include a septum access assembly that may be configured to limit the
number of times that the user may refill reservoir 118.
[0203] For example and referring also to FIGS. 5A-5C, septum access
assembly 152 may include shutter assembly 154 that may be held in an
"open" position by a tab assembly 156 that is configured to fit within a
slot assembly 158. Upon penetrating septum 146 with filling syringe 160,
shutter assembly 154 may be displaced downward, resulting in tab assembly
156 disengaging from slot assembly 158. Once disengaged, spring assembly
162 may displace shutter assembly 154 in the direction of arrow 164,
resulting in septum 146 no longer being accessible to the user.
[0204] Referring also to FIG. 6A, an alternative-embodiment septum access
assembly 166 is shown in the "open" position. In a fashion similar to
that of septum access assembly 152, septum access assembly 166 includes
shutter assembly 168 and spring assembly 170.
[0205] Referring also to FIG. 6B, an alternative-embodiment of septum
access assembly 172 is shown in the "open" position where tab 178 may
engage slot 180. In a fashion similar to that of septum access assembly
166, septum access assembly 172 may include shutter assembly 174 and
spring assembly 176. Once shutter assembly 172 moves to the "closed"
position (e.g., which may prevent further access of septum 146 by the
user), tab 178 may at least partially engage slot 180a. Engagement
between tab 178 and slot 180a may lock shutter assembly 172 in the
"closed" position to inhibit tampering and reopening of shutter assembly
172. Spring tab 182 of shutter assembly 172 may bias tab 178 into
engagement with slot 180a.
[0206] However, in various embodiments, septum access assemblies may not
be actuated linearly. For example and referring also to FIGS. 7A-7B,
there is shown alternative embodiment septum access assembly 184 that
includes shutter assembly 186 that is configured to pivot about axis 188.
When positioned in the open position (as shown in FIG. 7A), septum 146
may be accessible due to passage 190 (in shutter assembly 186) being
aligned with passage 192 in e.g., a surface of disposable housing
assembly 114. However, in a fashion similar to septum access assemblies
166, 172, upon penetrating septum 146 with filling syringe 160 (See FIG.
6B), shutter assembly 186 may be displaced in a clockwise fashion,
resulting in passage 190 (in shutter assembly 186) no longer being
aligned with passage 192 in e.g., a surface of disposable housing
assembly 114, thus preventing access to septum 146.
[0207] Referring also to FIGS. 8A-8B, an alternative-embodiment septum
access assembly 194 is shown. In a fashion similar to that of septum
access assemblies 166, 172, septum access assembly 194 includes shutter
assembly 196 and spring assembly 198 that is configured to bias shutter
assembly 196 in the direction of arrow 200. Filling assembly 202 may be
used to fill reservoir 118. Filling assembly 202 may include shutter
displacement assembly 204 that may be configured to displace shutter
assembly 196 in the direction of arrow 206, which in turn aligns passage
208 in shutter assembly 196 with septum 146 and passage 210 in septum
access assembly 194, thus allowing filling syringe assembly 212 to
penetrate septum 146 and fill reservoir 118.
[0208] Infusion pump assembly 100 may include a sealing assembly 150 (FIG.
3) configured to provide a seal between reusable housing assembly 102 and
disposable housing assembly 114. For example, when reusable housing
assembly 102 and disposable housing assembly 114 are engaged by e.g.
rotational screw-on engagement, twist-lock engagement or compression
engagement, reusable housing assembly 102 and disposable housing assembly
114 may fit together snuggly, thus forming a seal. In some embodiments,
it may be desirable for the seal to be more secure. Accordingly, sealing
assembly 150 may include an o-ring assembly (not shown). Alternatively,
sealing assembly 150 may include an over molded seal assembly (not
shown). The use of an o-ring assembly or an over molded seal assembly may
make the seal more secure by providing a compressible rubber or plastic
layer between reusable housing assembly 102 and disposable housing
assembly 114 when engaged thus preventing penetration by outside fluids.
In some instances, the o-ring assembly may prevent inadvertent
disengagement. For example, sealing assembly 150 may be a watertight seal
assembly and, thus, enable a user to wear infusion pump assembly 100
while swimming, bathing or exercising.
[0209] Referring also to FIG. 9, infusion pump assembly 100 may include an
external infusion set 134 configured to deliver the infusible fluid to a
user. External infusion set 134 may be in fluid communication with cavity
118, e.g. by way of the fluid path. External infusion set 134 may be
disposed adjacent to infusion pump assembly 100. Alternatively, external
infusion set 134 may be configured for application remote from infusion
pump assembly 100, as discussed in greater detail below. External
infusion set 134 may include a cannula assembly 136, which may include a
needle or a disposable cannula 138, and tubing assembly 140. Tubing
assembly 140 may be in fluid communication with reservoir 118, for
example, by way of the fluid path, and with cannula assembly 138 for
example, either directly or by way of a cannula interface 142.
[0210] External infusion set 134 may be a tethered infusion set, as
discussed above regarding application remote from infusion pump assembly
100. For example, external infusion set 134 may be in fluid communication
with infusion pump assembly 100 through tubing assembly 140, which may be
of any length desired by the user (e.g., 3-18 inches). Though infusion
pump assembly 100 may be worn on the skin of a user with the use of
adhesive patch 144, the length of tubing assembly 140 may enable the user
to alternatively wear infusion pump assembly 100 in a pocket. This may be
beneficial to users whose skin is easily irritated by application of
adhesive patch 144. Similarly, wearing and/or securing infusion pump
assembly 100 in a pocket may be preferable for users engaged in physical
activity.
[0211] In addition to/as an alternative to adhesive patch 144, a hook and
loop fastener system (e.g. such as hook and loop fastener systems offered
by Velcro USA Inc. of Manchester, N.H.) may be utilized to allow for easy
attachment/removal of an infusion pump assembly (e.g., infusion pump
assembly 100) from the user. Accordingly, adhesive patch 144 may be
attached to the skin of the user and may include an outward facing hook
or loop surface. Additionally, the lower surface of disposable housing
assembly 114 may include a complementary hook or loop surface. Depending
upon the separation resistance of the particular type of hook and loop
fastener system employed, it may be possible for the strength of the hook
and loop connection to be stronger than the strength of the adhesive to
skin connection. Accordingly, various hook and loop surface patterns may
be utilized to regulate the strength of the hook and loop connection.
[0212] Referring also to FIGS. 10A-10E, five examples of such hook and
loop surface patterns are shown. Assume for illustrative purposes that
the entire lower surface of disposable housing assembly 114 is covered in
a "loop" material. Accordingly, the strength of the hook and loop
connection may be regulated by varying the pattern (i.e., amount) of the
"hook" material present on the surface of adhesive patch 144. Examples of
such patterns may include but are not limited to: a singular outer circle
220 of "hook" material (as shown in FIG. 10A); a plurality of concentric
circles 222, 224 of "hook" material (as shown in FIG. 10B); a plurality
of radial spokes 226 of "hook" material (as shown in FIG. 10C); a
plurality of radial spokes 228 of "hook" material in combination with a
single outer circle 230 of "hook" material (as shown in FIG. 10D); and a
plurality of radial spokes 232 of "hook" material in combination with a
plurality of concentric circles 234, 236 of "hook" material (as shown in
FIG. 10E).
[0213] Additionally and referring also to FIG. 11A, in one exemplary
embodiment of the above-described infusion pump assembly, infusion pump
assembly 100' may be configured via a remote control assembly 300. In
this particular embodiment, infusion pump assembly 100' may include
telemetry circuitry (not shown) that allows for communication (e.g.,
wired or wireless) between infusion pump assembly 100' and e.g., remote
control assembly 300, thus allowing remote control assembly 300 to
remotely control infusion pump assembly 100'. Remote control assembly 300
(which may also include telemetry circuitry (not shown) and may be
capable of communicating with infusion pump assembly 100') may include
display assembly 302 and input assembly 304. Input assembly 304 may
include slider assembly 306 and switch assemblies 308, 310. In other
embodiments, the input assembly may include a jog wheel, a plurality of
switch assemblies, or the like.
[0214] Remote control assembly 300 may include the ability to pre-program
basal rates, bolus alarms, delivery limitations, and allow the user to
view history and to establish user preferences. Remote control assembly
300 may also include a glucose strip reader.
[0215] During use, remote control assembly 300 may provide instructions to
infusion pump assembly 100' via wireless communication channel 312
established between remote control assembly 300 and infusion pump
assembly 100'. Accordingly, the user may use remote control assembly 300
to program/configure infusion pump assembly 100'. Some or all of the
communication between remote control assembly 300 and infusion pump
assembly 100' may be encrypted to provide an enhanced level of security.
[0216] Communication between remote control assembly 300 and infusion pump
assembly 100' may be accomplished utilizing a standardized communication
protocol. Further, communication between the various components included
within infusion pump assembly 100, 100' may be accomplished using the
same protocol. One example of such a communication protocol is the Packet
Communication Gateway Protocol (PCGP) developed by DEKA Research &
Development of Manchester, N.H. As discussed above, infusion pump
assembly 100, 100' may include electrical control assembly 110 that may
include one or more electrical components. For example, electrical
control assembly 110 may include a plurality of data processors (e.g. a
supervisor processor and a command processor) and a radio processor for
allowing infusion pump assembly 100, 100' to communicate with remote
control assembly 300. Further, remote control assembly 300 may include
one or more electrical components, examples of which may include but are
not limited to a command processor and a radio processor for allowing
remote control assembly 300 to communicate with infusion pump assembly
100, 100'. A high-level diagrammatic view of one example of such a system
is shown in FIG. 11B.
[0217] Each of these electrical components may be manufactured from a
different component provider and, therefore, may utilize native (i.e.
unique) communication commands. Accordingly, through the use of a
standardized communication protocol, efficient communication between such
disparate components may be accomplished.
[0218] PCGP may be a flexible extendable software module that may be used
on the processors within infusion pump assembly 100, 100' and remote
control assembly 300 to build and route packets. PCGP may abstract the
various interfaces and may provide a unified application programming
interface (API) to the various applications being executed on each
processor. PCGP may also provide an adaptable interface to the various
drivers. For illustrative purposes only, PCGP may have the conceptual
structure illustrated in FIG. 11C for any given processor.
[0219] PCGP may ensure data integrity by utilizing cyclic redundancy
checks (CRCs). PCGP may also provide guaranteed delivery status. For
example, all new messages should have a reply. If such a reply isn't sent
back in time, the message may time out and PCGP may generate a negative
acknowledge reply message for the application (i.e., a NACK).
Accordingly, the message-reply protocol may let the application know
whether the application should retry sending a message.
[0220] PCGP may also limit the number of messages in-flight from a given
node, and may be coupled with a flow-control mechanism at the driver
level to provide a deterministic approach to message delivery and may let
individual nodes have different quantities of buffers without dropping
packets. As a node runs out of buffers, drivers may provide back pressure
to other nodes and prevent sending of new messages.
[0221] PCGP may use a shared buffer pool strategy to minimize data copies,
and may avoid mutual exclusions, which may have a small affect on the API
used to send/receive messages to the application, and a larger affect on
the drivers. PCGP may use a "Bridge" base class that provides routing and
buffer ownership. The main PCGP class may be sub-classed from the bridge
base class. Drivers may either be derived from a bridge class, or talk to
or own a derived bridge class.
[0222] PCGP may be designed to work in an embedded environment with or
without an operating system by using a semaphore to protect shared data
such that some calls can be re-entrant and run on a multiple threads. One
illustrative example of such an implementation is shown in FIG. 11D. PCGP
may operate the same way in both environments, but there may be versions
of the call for specific processor types (e.g., the ARM 9/OS version). So
while the functionality may be the same, there may be an operating system
abstraction layer with slightly different calls tailored for e.g., the
ARM 9 Nucleus OS environment.
[0223] Referring also to FIG. 11E, PCGP may: [0224] allow multiple
Send/Reply calls to occur (on Pilot's ARM 9 on multiple tasks
re-entrant); [0225] have multiple drivers running asynchronously for RX
and TX on different interfaces; and [0226] provide packet ordering for
send/receive, and deterministic timeout on message send.
[0227] Each software object may ask the buffer manager for the next buffer
to use, and may then give that buffer to another object. Buffers may pass
from one exclusive owner to another autonomicly, and queues may occur
automatically by ordering buffers by sequence number. When a buffer is no
longer in use, the buffer may be recycled (e.g., object attempts to give
the buffer to itself, or frees it for the buffer manager to re-allocate
later). Accordingly, data generally doesn't need to be copied, and
routing simply writes over the buffer ownership byte.
[0228] Such an implementation of PCGP may provide various benefits,
examples of which may include but are not limited to: [0229] dropping a
message due to lack of buffers may be impossible, as once a message is
put into a buffer, the message may live there until it is transferred or
received by the application; [0230] data may not need to be copied, as
offsets are used to access driver, PCGP and payload sections of a buffer;
[0231] drivers may exchange ownership of message data by writing over one
byte (i.e., the buffer ownership byte); [0232] there may be no need for
multiple exclusions except for re-entrant calls, as a mutual exclusion
may be needed only when a single buffer owner could simultaneously want
to use a buffer or get a new sequence number; [0233] there may be fewer
rules for application writers to follow to implement a reliable system;
[0234] drivers may use ISR/push/pull and polled data models, as there are
a set of calls provided to push/pull data out of the buffer management
system from the drivers; [0235] drivers may not do much work beyond TX
and RX, as drivers may not copy, CRC or check anything but the
destination byte and CRC and other checks may be done off of the ISR hot
path later; [0236] as the buffer manager may order access by sequence
number, queue ordering may automatically occur; and [0237] a small
code/variable foot print may be utilized; hot path code may be small and
overhead may be low.
[0238] As shown in FIG. 11F, when a message needs to be sent, the PCGP may
build the packet quickly and may insert it into the buffer management
system. Once in the buffer management system, a call to "packetProcessor"
may apply protocol rules and may give the messages to the
drivers/application.
[0239] To send a new message or send a reply, PCGP may: [0240] check the
call arguments to e.g., make sure the packet length is legal, destination
is ok, etc.; [0241] avoid trying to send a message across a link that is
down unless the down link is the radio node, which may allow PCGP to be
used by the radio processors to establish a link, pair, etc. and may
notify the application when PCGP is trying to talk across a link that is
not functional (instead of timing out); [0242] obtain a sequence number
for a new message or utilize an existing sequence number for an existing
message; [0243] build the packet, copy the payload data and write in the
CRC, wherein (from this point forward) the packet integrity may be
protected by the CRC; and [0244] either give the message to the buffer
manager as a reply or as a new message, and check to see if putting this
buffer into the buffer manager would exceed the maximum number of
en-queued send messages.
[0245] Referring also to FIGS. 11G-11H, PCGP may work by doing all of the
main work on one thread to avoid mutual exclusions, and to avoid doing
considerable work on the send/reply or driver calls. The
"packetProcessor" call may have to apply protocol rules to replies, new
sent messages, and received messages. Reply messages may simply get
routed, but new messages and received messages may have rules for routing
the messages. In each case, the software may loop while a message of the
right type is available to apply protocol rules until it cannot process
the packets.
[0246] Sending a new message may conform to the following rules: [0247]
only two messages may be allowed "in-flight" on the network; and [0248]
enough data about an in-flight message may be stored to match the
response and handle timeout.
[0249] Receiving a message may conform to the following rules: [0250]
responses that match may clear out the "in-flight" information slot so a
new packet can be sent; [0251] responses that do not match may be
dropped; [0252] new messages may be for the protocol (e.g.,
getting/clearing network statistics for this node); [0253] to receive a
message, the buffer may be given up to the application and may use a call
back; and [0254] the buffer may be freed or left owned by the
application.
[0255] Accordingly, PCGP may be configured such that: [0256] the call
back function may copy the payload data out or may use it completely
before returning; [0257] the call back function owns the buffer and may
reference the buffer and the buffer's payload by the payload address,
wherein the message may be processed later; [0258] applications may poll
the PCGP system for received messages; and [0259] applications may use
the call back to set an event and then poll for received messages.
[0260] The communication system may have a limited number of buffers. When
PCGP runs out of buffers, drivers may stop receiving new packets and the
application may be told that the application cannot send new packets. To
avoid this and maintain optimal performance, the application may try to
perform one or more procedures, examples of which may include but are not
limited to: [0261] a) The application should keep PCGP up to date with
radio status: Specifically, if the link goes down and PCGP doesn't know,
PCGP may accept and queue new messages to send (or not timeout messages
optimally), which may jam the send queue and delay the application from
using the link optimally. [0262] b) The application should call
"decrement timeouts" regularly: Optimally, every 20-100 milliseconds
unless the processor is asleep. In general, a message moves fast
(milliseconds) slow (seconds) or not at all. Timeouts are an attempt to
remove "in-flight" messages that should be dropped to free up buffers and
bandwidth. Doing this less often may delay when a new message gets sent,
or when the application can queue a new message. [0263] c) The
application should ask PCGP if it has work to do that is pending before
going to sleep: If PCGP has nothing to do, driver activity may wake up
the system and thus PCGP, and then PCGP won't need a call to
"packetProcessor" or "decrement timeouts" until new packets enter the
system. Failure to do this may cause messages that could have been
sent/forwarded/received successfully to be dropped due to a timeout
condition. [0264] d) The application should not hold onto received
messages indefinitely: The message system relies on prompt replies. If
the application is sharing PCGP buffers, then holding onto a message
means holding onto a PCGP buffer. The receiving node doesn't know if the
sending node has timeout configured for slow or fast radio. This means
when a node receives a message it should assume the network's fast
timeout speed. [0265] e) The application should call the
"packetProcessor" often: The call may cause new messages queued by the
application to get sent and may handle receipt of new messages. The call
may also cause buffers to re-allocate and calling it infrequently may
delay message traffic.
[0266] As shown in FIG. 11I, at some point the RX driver may be asked to
receive a message from the other side of the interface. To ensure a
message does not get dropped, the RX driver may ask the buffer manager if
there is an available buffer for storing a new message. The driver may
then ask for a buffer pointer and may start filling the buffer with
received data. When a complete message is received, the RX driver may
call a function to route the packet. The route function may examine the
destination byte in the packet header and may change the owner to either
the other driver, or the application, or may detect that the packet is
bad and may drop the packet by freeing the buffer.
[0267] PCGP RX overhead may consist of asking for the next available
buffer and calling the route function. An example of code that performs
such a function is as follows:
TABLE-US-00001
@ Receive request
uint8 i=0, *p;
if (Bridge::canReceiveFlowControl( ) )
{
p = Bridge::nextBufferRX( );
while (not done) { p[i] = the next byte; }
Bridge::route(p);
}
[0268] A driver may perform a TX by asking the buffer manager for the
pointer to the next buffer to send. The TX driver may then ask the other
side of the interface if it can accept a packet. If the other side denies
the packet, the TX driver may do nothing to the buffer, as its status has
not changed. Otherwise, the driver may send the packet and may
recycle/free the buffer. An example of code that performs such a function
is as follows:
TABLE-US-00002
uint8 *p = Bridge::nextBufferTX( );
if (p != (uint8 *)0)
{
send the buffer p;
Bridge::recycle(p);
}
[0269] To avoid forwarding packets that are past the maximum message
system timeout time, asking for the nextBuffer may call the
BufferManager::first(uint8 owner) function that may scan for buffers to
free. Accordingly, full TX buffers with no hope of making a timeout may
be freed on the thread that owns the buffer. A bridge that is doing TX
(i.e., while looking for the next TX buffer) may free all of the TX
buffers that are expired before receiving the next TX buffer for
processing.
[0270] As shown in FIG. 11J-11L, during the buffer allocation process,
buffers marked free may be transferred to the drivers to receive new
packets, or to PCGP to receive new payloads for TX. Allocation from
"free" may be done by the "packetProcessor" function. The number of sends
and receives between "packetProcessor" calls may dictate how many
LT_Driver_RX, GT_Driver_RX and PCGP_Free buffers need to be allocated.
LT_Driver may represent drivers that handle addresses that are less than
the node address. GT_Driver may represent drivers that handle addresses
that are greater than the node address.
[0271] When a driver receives a packet, the driver may put the data into
an RX buffer that gets handed to the router. The router may then reassign
the buffer to PCGP_Receive or to the other driver's TX (not shown). If
the buffer contains obviously invalid data, the buffer may transition to
free.
[0272] After a router marks a buffer for TX, the driver may discover the
buffer is TX and may send the message. After sending the message, the
buffer may immediately become an RX buffer if the driver was low in RX
buffers, or the buffer may be freed for re-allocation.
[0273] During the "packetProcessor" call, PCGP may process all buffers
that the router marked as PCGP_Receive. At this point, data may be acted
upon, so the CRC and other data items may be checked. If the data is
corrupted, a statistic may be incremented and the buffer may be freed.
Otherwise, the buffer may be marked as owned by the application. Buffers
marked as owned by the application may be either recycled for the use of
PCGP or freed for reallocation by the buffer manager.
[0274] When the application wants to send a new message, it may be done in
a re-entrant friendly/mutual exclusion manner. If the buffer may be
allocated, PCGP may mark the buffer as busy. Once marked busy, no other
thread calling the send or reply functions may grab this buffer, as it is
owned by this function call's invocation. The remainder of the process of
error checking and building the message may be done outside the isolated
race condition mutual exclusion guarded code. The buffer may either
transition to free or may become a valid filled CRC-checked buffer and
passed to the router. These buffers may not be routed immediately and may
be queued so that messages can be sent later (assuming that protocol
rules allow). Reply messages may be marked differently than new send
messages because reply messages may be routed with a higher priority than
regular send messages and reply messages may have no rules limiting how
many/when they can be sent.
[0275] PCGP was designed to work with flow control, and flow control may
negotiate the transfer of messages from one node to another node so that
a buffer is never dropped because the other side of an interface lacks a
buffer (which may cause back pressure on the sending node).
[0276] Flow control may be apart of the shared buffer format. The first
two bytes may be reserved for the driver so that the driver never needs
to shift the packet bytes. Two bytes may be used so that one byte is the
DMA length -1, and the second byte is to control the flow of messages.
These same two bytes may be synchronizing bytes if a PCGP message is
transmitted over RS232.
[0277] When a packet is "in-flight", the packet may be in the process of
being sent by a driver on the way to its destination, being processed by
the destination, or being sent back as a response.
[0278] Typical delays are as follows:
TABLE-US-00003
Interface/Delay cause Delay (seconds) Notes
SPI <3 Roughly 400 kbps
I2C <1
Waking a CC2510 <6? Clock calibration, min. sleep
time.
Flow control <0.2
RF link 20 to 2000
Interference/separation Minutes, never
[0279] Accordingly, messages tend to complete the round trip either:
quickly (e.g., <50 ms); slowly (e.g., one or more seconds); or not at
all.
[0280] PCGP may use two different times (set at initialization) for all
timeouts, one for when the RF link is in fast heartbeat mode, and another
for when the RF link is in slow mode. If a message is in-flight and the
link status changes from fast to slow, the timeout may be adjusted and
the difference between fast and slow may be added to the time-to-live
counter for the packet. No additional transitions back and forth may
affect the time-to-live time for the message.
[0281] There is a second timeout that may be twice as long as the slow
timeout that is used to monitor buffer allocation inside PCGP.
Accordingly, if a message is "stuck" inside a driver and hasn't been sent
due to e.g., flow control or hardware damage, the buffer may be freed by
the buffer manager, resulting in the buffer being dropped. For a "new"
message, this may mean that the packet already timed out and the
application was already given a reply saying the message wasn't
delivered, resulting in the buffer being freed. Since the driver polls
the buffer manager for buffers that need to be sent, the buffer is freed
up so that a message that could be sent is handed to the driver the next
time that it unblocks. For a reply message, the reply may simply get
dropped and the sending node may time out.
[0282] The PCGP messaging system may pass messages that contain header
information and payload. Outside of PCGP, the header may be a set of data
items in a call signature. However, internal to PCGP, there may be a
consistent, driver friendly byte layout. Drivers may insert bytes either
into the PCGP packet or before the PCGP packet such: [0283] DE, CA:
Synch bytes for use with RS232, nominal value of 0xDE, 0xCA or 0x5A,
0xA5. [0284] LD: Driver DMA length byte, equals amount driver is pushing
in this DMA transfer, which is the total size, not including the size
byte or synch bytes. [0285] Cmd: Driver command and control byte used for
flow control. [0286] LP: PCGP packet length, always the total
header+payload size in bytes+CRC size. LD=LP+1. [0287] Dst: Destination
address. [0288] Src: Source address [0289] Cmd: Command byte [0290] Scd:
Sub command byte [0291] AT: Application Tag is defined by the application
and has no significance to PCGP. It allows the application to attach more
information to a message e.g., the thread from which the message
originated. [0292] SeqNum: thirty-two bit sequence number is incremented
by PCGP for a new message sent, guarantees the number will not wrap, acts
as a token, endianess isn't relevant. [0293] CRC16: A sixteen bit CRC of
the PCGP header and payload.
[0294] An example of a message with no payload, cmd=1, subcmd=2 is as
follows: [0295] 0xDE, 0xCA, 0xC, 0x5, 0x14, 1, 2, 0, 0, 0, 0, 0x1,
crchigh, crclow. [0296] 0x0D, cmd, 0xC, 0x5, 0x14, 1, 2, 0, 0, 0, 0, 0x1,
crchigh, crclow.
[0297] There may be several advantages to this methodology, examples of
which may include but are not limited to: [0298] Most of our hardware
DMA engines may use the first byte to define how many additional bytes to
move, so in this methodology, drivers and PCGP may share buffers. [0299]
A byte may be provided right after the DMA length to pass flow control
information between drivers. [0300] Driver length and "Cmd" byte may be
outside the CRC region so they may be altered by the driver, may be owned
by the driver transport mechanism, and the driver may guard for invalid
lengths. [0301] There may be a separate PGCP packet length byte that is
CRC protected. Accordingly, the application may trust the that payload
length is correct. [0302] The endianness of the sequence number may not
be relevant, as it is just a byte pattern that may be matched that
happens to also be a thirty-two bit integer. [0303] The sequence number
may be four bytes aligned to the edge of the shared buffer pool length.
[0304] There may be optional RS232 synchronizing bytes so that users may
move cables around while debugging a message stream and both sides of the
interface may resynchronize. [0305] The application, driver and PCGP may
share buffers and may release them by pointer.
[0306] PCGP may not be an event driven software design, but may be used in
event driven architectures by how the sub-classes are written. Data may
be exchanged between the classes conceptually (as shown in FIG. 11M-11N).
[0307] Some event model in the driver may wake the driver, may receive a
message and may pass the message through the bridge into the buffer
manager that routes the message to new owner of the new message (through
a bridge to either a driver or PCGP).
[0308] The following summarizes some exemplary events:
TABLE-US-00004
Event: Possible use: Where this occurs:
When a new send or reply is Decide to run Inside
queued, or decTimeouts packetProcessor. PCGP::sendInternal
generates a timeout reply.
When a messages is received Decide to run BufferManager::give
for PCGP. packetProcessor.
When a driver has something Wake driver for BufferManager::give
new to send. TX.
When a Driver RX buffer Turn off flow BufferManager::give
becomes available. control.
[0309] The following illustrative example shows how the PCGP event model
may work with Nucleus to wakeup the PCGP task after every message send,
reply, or decTimeout that generated a NACK:
TABLE-US-00005
class PcgpOS : public Pcgp
{
virtual void schedulePacketProcessor(void)
{
OS_EventGrp_Set(g_RCVEvGrps[EVG_RF_TASK].pEvgHandle,
RfRadioTxEvent, OS_EV_OR_NO_CLEAR);
}
}
[0310] The following is a pseudo code driver that is event based,
illustrating how driver events work. The Driver subclasses Bridge and
overrides hasMessagesToSend and flowControlTurnedOff to schedule the TX
and RX functions to run if they aren't already running.
TABLE-US-00006
class SPI_Driver : public Bridge
{
virtual void hasMessagesToSend( )
{
Trigger_ISR(TX_ISR, this);
}
virtual void flowControlTurnedOff( )
{
Trigger_ISR(RX_ISR, this);
}
static void TX_RetryTimer( )
{
Trigger_ISR(TX_ISR, this);
}
static void TX_ISR(Bridge *b)
{
DisableISRs( );
do
{
uint8 *p = b->nextBufferTX( );
if (p == null) break;
if (b->_bufferManager->bufferTimedOut(p)==false)
{
if (OtherSideSPI_FlowControl( ) == false)
{
Trigger TX_RetryTimer in 20 msec.
break;
}
send(p);
}
free(p);
} while (true) ;
EnableISRs( );
}
static void RX_ISR(Bridge *b)
{
DisableISRs( );
do
{
uint8* p = b->nextBufferRX( );
if (p == null) break;
uint i;
while (not done receiving)
p[i++] = getChar( );
b->route(p);
} while (true) ;
EnableISRs( );
}
}
[0311] The following statistics may be supported by PCGP: [0312] Number
of packets sent; [0313] Number of packets received; [0314] CRC errors;
[0315] Timeouts; and [0316] Buffer unavailable (ran out of buffers)
[0317] PCGP may be designed to run in multiple processing environments.
Most parameters may be run time configured because it facilitates
testing, and any run time fine tuning for performance. Other parameters
may be compile time e.g., anything that alters memory allocation must be
done statically at compile time.
[0318] The following may be compile time configuration #defines that may
vary where PCGP is implemented: [0319] # driver bytes: may be two bytes
reserved in the common buffer scheme for the driver, but this may be a
compile time option to accommodate other drivers such as RF protocol.
[0320] # RX driver buffers: may be tuned to how many buffers would be
good for that processor/traffic flow, etc. [0321] # PCGP RX buffers: may
be tuned to how many buffers would be good for that processor/traffic
flow, etc. [0322] Total # of buffers: may be tuned to how many buffers
should be at that processor.
[0323] The CRC may be used to ensure data integrity. If a CRC is invalid,
it may not be delivered to the application and the CRC error may be
tracked. The message may eventually timeout and may be retried by the
originator.
[0324] Likewise, if the messaging system informs the application that a
message was delivered when it was not, this may be a hazard to the
system. The Stop Bolus Command is an example of such a command. This may
be mitigated by the Request/Action sequence of messages which may be
required by the application to change therapy. The Controller may receive
a matching command from the Pump application to consider the message
delivered.
[0325] DEKA may provide a reference way of interfacing PCGP into the
Nucleus OS system on the ARM 9 (as shown in FIG. 11O).
[0326] As shown in FIG. 11P, the pcgpOS.cpp file may instantiate a PCGP
node instance (Pcgp, a Bridge, etc.) and may provide through pcgpOS.h a
`C` linkable set of function calls that provide a `C` language interface
to the C++ code. This may simplify the `C` code as the objects acted upon
are implicit.
[0327] The following general rules may be applied: [0328] PCGP may run
on all nodes: any driver may support a generic driver interface. [0329]
Race conditions may not be permitted. [0330] May support half duplex on
the SPI port between slave processor and master processor. [0331] Data
transfer may not be attempted; as it either succeeds or returns
fail/false. [0332] May require low overhead (time, processing, bandwidth
wasted). [0333] May support CC2510 operating at DMA (fast) SPI clock
rates.
[0334] SPI flow control may prevent data from being sent if the receiving
side does not currently have an empty buffer to place the packet. This
may be accomplished by asking for permission to send and waiting for a
response indicating that you have been cleared to do so. There may also
be a way to tell the other side that there are currently no free buffers
and the transfer should be attempted at a later time.
[0335] All transmission may begin with a length byte that indicates the
number of bytes to be sent, not including the length byte itself.
Following the length may be a single byte indicating the command being
sent.
[0336] The actual transmission of a packet may be the length of packet
plus one for the command byte, followed by the command byte for a message
appended and finally the packet itself.
[0337] In addition to the command bytes that will be sent, an additional
hardware line called the FlowControl line may be added to the traditional
four SPI signals. The purpose of this line is to allow the protocol to
run as quickly as possible without a need for preset delays. It also
allows the slave processor to tell the master processor that it has a
packet waiting to be sent, thus eliminating the need for the master
processor to poll the slave processor for status.
[0338] The following exemplary command values may be used:
Commands to be sent by the master processor:
TABLE-US-00007
Command Value Description
M_RTS 0xC1 Master is requesting to send a packet
M_MSG_APPENDED 0xC2 Master is sending a packet
M_CTS 0xC3 Master is tell slave it is Cleared to Send
M_ERROR 0xC4 An Error condition has been
encountered
Commands to be sent by the slave processor:
TABLE-US-00008
Command Value Description
S_PREPARING_FOR_RX 0xA1 Slave is prepare the dma to receive
a packet
S_RX_BUFF_FULL 0xA2 Slave is currently out of RX
buffers, retry later
S_MSG_APPENDED 0xA3 Slave is sending a packet
S_ERROR 0xA4 An Error condition has been
encountered
[0339] As illustrated in FIG. 11Q, when the slave processor has a packet
to send to the master processor, the slave processor may notify the
master processor (by asserting the FlowControl line) that it has a
pending packet that is waiting to be sent. Doing so may result in an IRQ
on the master processor at which time the master processor may decide
when to go retrieve the message from the slave processor. Retrieving the
packet may be delayed at the discretion of the master processor, and the
master processor may even decide to attempt to send a packet to the slave
processor before retrieving from the slave processor.
[0340] The master processor may begin the retrieval by sending the slave
processor M_CTS commands; this shall be repeated until the slave
processor responds by sending the S_MSG_APPENDED command along with the
packet itself. The FlowControl line may be cleared after the packet has
been sent. If a M_CTS command is received by the slave processor when one
is not expected, the M_CTS command may be ignored.
[0341] As illustrated in FIG. 11R, when the master processor has a packet
to send to the slave processor, the master processor may initiate the
transfer by sending a M_RTS command. Upon receiving the M_RTS command, if
the slave processor currently has a send packet pending, the slave
processor will lower the FlowControl line so that it may be re-used as a
Cleared To Send signal. The slave processor may then tell the master
processor that it is in the process of preparing the SPI DMA to receive
the packet, during which time the master processor may stop clocking
bytes onto the bus and may allow the slave processor to finish preparing
for the receive.
[0342] The slave processor may then indicate it is ready to receive the
full packet by raising the FlowControl line (which is now used as the CTS
signal). Upon receiving the CTS signal, the master processor may proceed
to send the M_MSG_APPENDED command along with the packet itself.
[0343] After the completion of the transfer, the slave processor may lower
the FlowControl line. If a packet was pending at the start of the
transfer, or a send occurred on the slave processor when the packet was
being received, the slave processor may reassert the FlowControl line now
indicating that it has a pending packet.
[0344] Referring again to FIG. 11A, infusion pump assembly 100, 100' may
include switch assembly 318 coupled to electrical control assembly 110
(FIG. 3) that may allow a user (not shown) to perform at least one, and
in some embodiments, a plurality of tasks. One illustrative example of
such a task is the administration of a bolus dose of the infusible fluid
(e.g., insulin) without the use of a display assembly. Remote control
assembly 300 may allow the user to enable/disable/configure infusion pump
assembly 100, 100' to administer the bolus dose of insulin.
[0345] Referring also to FIG. 12A, slider assembly 306 may be configured,
at least in part, to enable the user to manipulate the menu-based
information rendered on display assembly 302. An example of slider
assembly 306 may include a capacitive slider assembly, which may be
implemented using a CY8C21434-24LFXI PSOC offered by Cypress
Semiconductor of San Jose, Calif., the design an operation of which are
described within the "CSD User Module" published by Cypress
Semiconductor. For example, via slider assembly 306, the user may slide
their finger in the direction of arrow 314, resulting in the highlighted
portion of the information included within main menu 350 (shown in FIG.
12A) rendered on display assembly 302 scrolling upward. Alternatively,
the user may slide their finger in the direction of arrow 316, resulting
in the highlighted portion of the information included within main menu
350 rendered on display assembly 302 scrolling downward.
[0346] Slider assembly 306 may be configured so that the rate at which
e.g. the highlighted portion of main menu 350 scrolls "upward" or
"downward" varies depending upon the displacement of the finger of the
user with respect to point of origin 320. Therefore, if the user wishes
to quickly scroll "upward", the user may position their finger near the
top of slider assembly 306. Likewise, if the user wishes to quickly
scroll "downward", the user may position their finger near the bottom of
slider assembly 306. Additionally, if the user wishes to slowly scroll
"upward", the user may position their finger slightly "upward" with
respect to point of origin 320. Further, if the user wishes to slowly
scroll "downward", the user may position their finger slightly "downward"
with respect to point of origin 320. Once the appropriate menu item is
highlighted, the user may select the highlighted menu item via one or
more switch assemblies 308, 310.
[0347] Referring also to FIGS. 12B-12F, assume for illustrative purposes
that infusion pump assembly 100, 100' is an insulin pump and the user
wishes to configure infusion pump assembly 100, 100' so that when switch
assembly 318 is depressed by the user, a 0.20 unit bolus dose of insulin
is administered. Accordingly, the user may use slider assembly 306 to
highlight "Bolus" within main menu 350 rendered on display assembly 302.
The user may then use switch assembly 308 to select "Bolus". Once
selected, processing logic (not shown) within remote control assembly 300
may then render submenu 352 on display assembly 302 (as shown in FIG.
12B).
[0348] The user may then use slider assembly 306 to highlight "Manual
Bolus" within submenu 352, which may be selected using switch assembly
308. Processing logic (not shown) within remote control assembly 300 may
then render submenu 354 on display assembly 302 (as shown in FIG. 12C).
[0349] The user may then use slider assembly 306 to highlight "Bolus: 0.0
Units" within submenu 354, which may be selected using switch assembly
308. Processing logic (not shown) within remote control assembly 300 may
then render submenu 356 on display assembly 302 (as shown in FIG. 12D).
[0350] The user may then use slider assembly 306 to adjust the "Bolus"
insulin amount to "0.20 units", which may be selected using switch
assembly 308. Processing logic (not shown) within remote control assembly
300 may then render submenu 358 on display assembly 302 (as shown in FIG.
12E).
[0351] The user 14 may then use slider assembly 306 to highlight
"Confirm", which may be selected using switch assembly 308. Processing
logic (not shown) within remote control assembly 300 may then generate
the appropriate signals that may be sent to the above-described telemetry
circuitry (not shown) included within remote control assembly 300. The
telemetry circuitry (not shown) included within the remote control
assembly may then transmit, via wireless communication channel 312
established between remote control assembly 300 and infusion pump
assembly 100', the appropriate configuration commands to configure
infusion pump assembly 100' so that whenever switch assembly 318 is
depressed by the user, a 0.20 unit bolus dose of insulin is administered.
[0352] Once the appropriate commands are successfully transmitted,
processing logic (not shown) within remote control assembly 300 may once
again render submenu 350 on display assembly 302 (as shown in FIG. 12F).
[0353] Specifically and once programmed via remote control assembly 300,
the user may depress switch assembly 318 of infusion pump assembly 100'
to administer the above-described 0.20 unit bolus dose of insulin. Via
the above-described menuing system included within remote control
assembly 300, the user may define a quantity of insulin to be
administered each time that the user depresses switch assembly 318. While
this particular example specifies that a single depression of switch
assembly 318 is equivalent to 0.20 units of insulin, this is for
illustrative purposes only and is not intended to be a limitation of this
disclosure, as other values (e.g. 1.00 units of insulin per depression)
are equally applicable.
[0354] Assume for illustrative purposes that the user wishes to administer
a 2.00 unit bolus dose of insulin. To activate the above-describe bolus
dose administration system, the user may be required to press and hold
switch assembly 318 for a defined period of time (e.g. five seconds), at
which point infusion pump assembly 100, 100' may generate an audible
signal indicating to the user that infusion pump assembly 100, 100' is
ready to administer a bolus does of insulin via switch assembly 318.
Accordingly, the user may depress switch assembly 318 ten times (i.e.,
2.00 units is ten 0.20 unit doses). After each time that switch assembly
318 is depressed, infusion pump assembly 100, 100' may provide on audible
response to the user via an internal speaker/sound generation device (not
shown). Accordingly, the user may depress switch assembly 318 the first
time and infusion pump assembly 100, 100' may generate a confirmation
beep in response, thus indicating to the user that infusion pump assembly
100, 100' received the command for (in this particular example) 0.20
units of insulin. As the desired bolus dose is 2.00 units of insulin, the
user may repeat this procedure nine more times in order to effectuate a
bolus dose of 2.00 units, wherein infusion pump assembly 100, 100'
generates a confirmation beep after each depression of switch assembly
318.
[0355] While in this particular example, infusion pump assemblies 100,
100' are described as providing one beep after each time the user
depresses switch assembly 318, this is for illustrative purposes only and
is not intended to be a limitation of this disclosure. Specifically,
infusion pump assembly 100, 100' may be configured to provide a single
beep for each defined quantity of insulin. As discussed above, a single
depression of switch assembly 318 may be equivalent to 0.20 units of
insulin. Accordingly, infusion pump assembly 100, 100' may be configured
to provide a single beep for each 0.10 units of insulin. Accordingly, if
infusion pump assembly 100, 100' is configured such that a single
depression of switch assembly 318 is equivalent to 0.20 units of insulin,
each time switch assembly 318 is depressed, infusion pump assembly 100,
100' may provide the user with two beeps (i.e. one for each 0.10 units of
insulin).
[0356] Once the user has depressed switch assembly 318 on infusion pump
assembly 100' a total of ten times, the user may simply wait for infusion
pump assembly 100, 100' to acknowledge receipt of the instructions to
administer a 2.00 unit bolus dose of insulin (as opposed to the
confirmation beep received at each depression of switch assembly 318).
Once a defined period of time (e.g., two seconds) passes, infusion pump
assembly 100, 100' may provide an audible confirmation to the user
concerning the quantity of units to be administered via the bolus insulin
dose that the user just requested. For example, as (in this example)
infusion pump assembly 100, 100' was programmed by the user so that a
single depression of switch assembly 318 is equivalent to 0.20 units of
insulin, infusion pump assembly 100, 100' may beep ten times (i.e., 2.00
units is ten 0.20 unit doses).
[0357] When providing feedback to the user concerning the quantity of
units to be administered via the bolus insulin dose, infusion pump
assembly 100, 100' may provide a multifrequency audible confirmation. For
example and continuing with the above-stated example in which ten beeps
are to be provided to the user, infusion pump assembly 100, 100' may
group the beeps into groups of five (to facilitate easier counting by the
user) and the beeps within each group of five may be rendered by infusion
pump assembly 100, 100' so that each subsequent beep has a higher
frequency than the preceding beep (in a manner similar to a musical
scale). Accordingly and continuing with the above-stated example,
infusion pump assembly 100, 100' may render a 1,000 Hz beep, followed by
an 1,100 Hz beep, followed by a 1,200 Hz beep, followed by a 1,300 Hz
beep, followed by a 1,400 Hz beep (thus completing a group of five
beeps), followed by a short pause, and then a 1,000 Hz beep, followed by
an 1,100 Hz beep, followed by a 1,200 Hz beep, followed by a 1,300 Hz
beep, followed by a 1,400 Hz beep (thus completing the second group of
five beeps). According to various additional/alternative embodiments the
multifrequency audible confirmation may utilize various numbers of tones
incrementing in frequency. For example, an embodiment may utilize twenty
different tones incrementing in frequency. However, the number of tones
should not be construed as a limitation of the present disclosure as
number of tones may vary according to design criteria and user need.
[0358] Once infusion pump assembly 100, 100' completes the rendering of
the multifrequency audible confirmation (i.e. the ten beeps described
above), the user may, within a defined period of time (e.g. two seconds),
depress switch assembly 318 to provide a confirmation signal to infusion
pump assembly 100, 100', indicating that the multifrequency audible
confirmation was accurate and indicative of the size of the bolus dose of
insulin to be administered (i.e. 2.00 units). Upon receiving this
confirmation signal, infusion pump assembly 100, 100' may render a
"confirmation received" audible tone and effectuate the delivery of (in
this particular example) the 2.00 unit bolus dose of insulin. In the
event that infusion pump assembly 100, 100' fails to receive the
above-described confirmation signal, infusion pump assembly 100, 100' may
render a "confirmation failed" audible tone and will not effectuate the
delivery of the bolus dose of insulin. Accordingly, if the multifrequency
audible confirmation was not accurate/indicative of the size of the bolus
dose of insulin to be administered, the user may simply not provide the
above-described confirmation signal, thereby canceling the delivery of
the bolus dose of insulin.
[0359] As discussed above, in one exemplary embodiment of the
above-described infusion pump assembly, infusion pump assembly 100' may
be used to communicate with a remote control assembly 300. When such a
remote control assembly 300 is utilized, infusion pump assembly 100' and
remote control assembly 300 may routinely contact each other to ensure
that the two devices are still in communication with each other. For
example, infusion pump assembly 100' may "ping" remote control assembly
300 to ensure that remote control assembly 300 is present and active.
Further, remote control assembly 300 may "ping" infusion pump assembly
100' to ensure that infusion pump assembly 100' is still present and
active. In the event that one of infusion pump assembly 100' and remote
control assembly 300 fails to establish communication with the other
assembly, the assembly that is unable to establish communication may
sound a "separation" alarm. For example, assume that remote control
assembly 300 is left in the car of the user, while infusion pump assembly
100' is in the pocket of the user. Accordingly and after a defined period
of time, infusion pump assembly 100' may begin sounding the "separation"
alarm, indicating that communication with remote control assembly 300
cannot be established. Using switch assembly 318, the user may
acknowledge/silence this "separation" alarm.
[0360] As the user may define and administer a bolus insulin dose via
switch assembly 318 of infusion pump assembly 100' while remote control
assembly 300 is not in communication with infusion pump assembly 100',
infusion pump assembly 100' may store information concerning the
administered bolus insulin dose within a log file (not shown) stored
within infusion pump assembly 100'. This log file (not shown) may be
stored within nonvolatile memory (not shown) included within infusion
pump assembly 100'. Upon communication being reestablished between
infusion pump assembly 100' and remote control assembly 300, infusion
pump assembly 100' may provide the information concerning the
administered bolus insulin dose stored within the log file (not shown) of
infusion pump assembly 100' to remote control assembly 300.
[0361] Further, if the user anticipates separating remote control assembly
300 from infusion pump assembly 100', the user (via the above-described
menuing system) may configure infusion pump assembly 100' and remote
control assembly 300 to be in "separation" mode, thus eliminating the
occurrence of the above-described "separation" alarms. However, the
devices may continue to "ping" each other so that when they come back
into communication with each other, infusion pump assembly 100' and
remote control assembly 300 may automatically exit "separation" mode.
[0362] Further, if the user anticipates traveling in an airplane, the user
(via the above-described menuing system of remote control assembly 300)
may configure infusion pump assembly 100' and remote control assembly 300
to be in "airplane" mode, in which each of infusion pump assembly 100'
and remote control assembly 300 suspend any and all data transmissions.
While in "airplane" mode, infusion pump assembly 100' and remote control
assembly 300 may or may not continue to receive data.
[0363] Switch assembly 318 may be used to perform additional functions,
such as: checking the battery life of reusable housing assembly 102;
pairing reusable housing assembly 102 with remote control assembly 300;
and aborting the administration of a bolus does of infusible fluid.
[0364] Checking Battery Life:
[0365] Reusable housing assembly 102 may include a rechargeable battery
assembly that may be capable of powering infusion pump assembly 100, 100'
for approximately three days (when fully charged). Such a rechargeable
battery assembly may have a usable life of a predetermined number of
usable hours, for example, or years, or other predetermined length of
usage. However, the predetermined life may depend on many factors,
including but not limited to, one or more of the following: climate,
daily usage, and number of recharges. Whenever reusable housing assembly
102 is disconnected from disposable housing assembly 114, infusion pump
assembly 100, 100' may perform a battery check on the above-described
rechargeable battery assembly whenever switch assembly 318 is depressed
for a defined period of time (e.g. in excess of two seconds). In the
event that the above-described rechargeable battery assembly is
determined to be charged above a desired threshold, infusion pump
assembly 100, 100' may render a "battery pass" tone. Alternatively, in
the event that the above-described rechargeable battery assembly is
determined to be charged below a desired threshold, infusion pump
assembly 100, 100' may render a "battery fail" tone. Infusion pump
assembly 100, 100' may include components and/or circuitry to determine
whether reusable housing assembly 102 is disconnected from disposable
housing assembly 114.
[0366] Pairing:
[0367] As discussed above and in one exemplary embodiment of the
above-described infusion pump assembly, infusion pump assembly 100' may
be used to communicate with remote control assembly 300. In order to
effectuate communication between infusion pump assembly 100' and remote
control assembly 300, a paring process may be performed. During such a
pairing process, one or more infusion pump assemblies (e.g. infusion pump
assembly 100') may be configured to communicate with remote control
assembly 300 and (conversely) remote control assembly 300 may be
configured to communicate with one or more infusion pump assemblies (e.g.
infusion pump assembly 100'). Specifically, the serial numbers of the
infusion pump assemblies (e.g. infusion pump assembly 100') may be
recorded within a pairing file (not shown) included within remote control
assembly 300 and the serial number of remote control assembly 300 may be
recorded within a pairing file (not shown) included within the infusion
pump assemblies (e.g. infusion pump assembly 100').
[0368] According to an embodiment, in order to effectuate such a pairing
procedure, the user may simultaneously hold down one or more switch
assemblies on both remote control assembly 300 and infusion pump assembly
100'. For example, the user may simultaneously hold down switch assembly
310 included within remote control assembly 300 and switch assembly 318
included within infusion pump assembly 100' for a defined period
exceeding e.g. five seconds. Once this defined period is reached, one or
more of remote control assembly 300 and infusion pump assembly 100' may
generate an audible signal indicating that the above-described pairing
procedure has been effectuated.
[0369] According to another embodiment, prior to performing the pairing
process, the user may uncouple reusable housing assembly 102 from
disposable housing assembly 114. By requiring this initial step, further
assurance is provided that an infusion pump assembly being worn by a user
may not be surreptitiously paired with a remote control assembly.
[0370] Once uncoupled, the user may enter pairing mode via input assembly
304 of remote control assembly 300. For example, the user may enter
pairing mode on remote control assembly 300 via the above-described
menuing system in combination with e.g., switch assembly 310. The user
may be prompted on display assembly 302 of remote control assembly 300 to
depress and hold switch assembly 318 on infusion pump assembly 100'.
Additionally, remote control assembly 304 may switch to a low power mode
to e.g., avoid trying to pair with distant infusion pump assemblies. The
user may then depress and hold switch assembly 318 on infusion pump
assembly 100' so that infusion pump assembly 100' enters a receive mode
and waits for a pairing command from remote control assembly 300.
[0371] Remote control assembly 300 may then transmit a pairing request to
infusion pump assembly 100', which may be acknowledged by infusion pump
assembly 100'. Infusion pump assembly 100' may perform a security check
on the pairing request received from remote control assembly 300 and (if
the security check passes) infusion pump assembly 100' may activate a
pump pairing signal (i.e., enter active pairing mode). Remote control
assembly 300 may perform a security check on the acknowledgment received
from infusion pump assembly 100'.
[0372] The acknowledgment received from infusion pump assembly 100' may
define the serial number of infusion pump assembly 100' and remote
control assembly 300 may display that serial number on display assembly
302 of remote control assembly 300. The user may be asked if they wish to
pair with the pump found. If the user declines, the pairing process may
be aborted. If the user agrees to the pairing process, remote control
assembly 300 may prompt the user (via display assembly 302) to depress
and hold switch assembly 318 on infusion pump assembly 100'.
[0373] The user may then depress and hold switch assembly 318 on infusion
pump assembly 100' and depress and hold e.g. switch assembly 310 on
remote control assembly 300.
[0374] Remote control assembly 300 may confirm that remote switch assembly
310 was held (which may be reported to infusion pump assembly 100').
Infusion pump assembly 100' may perform a security check on the
confirmation received from remote control assembly 300 to confirm the
integrity of same. If the integrity of the confirmation received is not
verified, the pairing process is aborted. If the integrity of the
confirmation received is verified, any existing remote pair configuration
file is overwritten to reflect newly-paired remote control assembly 300,
the pump pairing completed signal is activated, and the pairing process
is completed.
[0375] Additionally, infusion pump assembly 100' may confirm that switch
assembly 318 was held (which may be reported to remote control assembly
300). Remote control assembly 300 may perform a security check on the
confirmation received from infusion pump assembly 100' to confirm the
integrity of same. If the integrity of the confirmation received is not
verified, the pairing process is aborted. If the integrity of the
confirmation received is verified, a pair list file within remote control
assembly 300 may be modified to add infusion pump assembly 100'.
Typically, remote control assembly 300 may be capable of pairing with
multiple infusion pump assemblies, while infusion pump assembly 100' may
be capable of only pairing with a single remote control assembly. The
pairing completed signal may be activated and the pairing process may be
completed.
[0376] When the pairing process is completed, one or more of remote
control assembly 300 and infusion pump assembly 100' may generate an
audible signal indicating that the above-described pairing procedure has
been successfully effectuated.
[0377] Aborting Bolus Dose:
[0378] in the event that the user wishes to cancel a bolus dose of e.g.
insulin being administered by infusion pump assembly 100', the user may
depress switch assembly 318 (e.g., shown in FIGS. 1 & 2) for a defined
period exceeding e.g. five seconds. Once this defined period is reached,
infusion pump assembly 100' may render an audible signal indicating that
the above-described cancellation procedure has been effectuated.
[0379] While switch assembly 318 is shown as being positioned on the top
of infusion pump assembly 100, 100', this is for illustrative purposes
only and is not intended to be a limitation of this disclosure, as other
configurations are possible. For example, switch assembly 318 may be
positioned about the periphery of infusion pump assembly 100, 100'.
[0380] Referring also to FIGS. 13-15, there is shown an
alternative-embodiment infusion pump assembly 400. As with pump assembly
100, 100', infusion pump assembly 400 may include reusable housing
assembly 402 and disposable housing assembly 404.
[0381] In a fashion similar to reusable housing assembly 102, reusable
housing assembly 402 may include a mechanical control assembly (that
includes at least one pump assembly and at least one valve assembly).
Reusable housing assembly 402 may also include an electrical control
assembly that is configured to provide control signals to the mechanical
control assembly and effectuate the delivery of an infusible fluid to a
user. The valve assembly may be configured to control the flow of the
infusible fluid through a fluid path and the pump assembly may be
configured to pump the infusible fluid from the fluid path to the user
[0382] In a fashion similar to disposable housing assembly 114, disposable
housing assembly 404 may be configured for a single use or for use for a
specified period of time, e.g., e.g., three days or any other amount of
time. Disposable housing assembly 404 may be configured such that any
components in infusion pump assembly 400 that come in contact with the
infusible fluid are disposed on and/or within disposable housing assembly
404.
[0383] In this particular embodiment of the infusion pump assembly,
infusion pump assembly 400 may include switch assembly 406 positioned
about the periphery of infusion pump assembly 400. For example, switch
assembly 406 may be positioned along a radial edge of infusion pump
assembly 400, which may allow for easier use by a user. Switch assembly
406 may be covered with a waterproof membrane configured to prevent the
infiltration of water into infusion pump assembly 400. Reusable housing
assembly 402 may include main body portion 408 (housing the
above-described mechanical and electrical control assemblies) and locking
ring assembly 410 that may be configured to rotate about main body
portion 408 (in the direction of arrow 412).
[0384] In a fashion similar to reusable housing assembly 102 and
disposable housing assembly 114, reusable housing assembly 402 may be
configured to releasably engage disposable housing assembly 404. Such
releasable engagement may be accomplished by a screw-on, a twist-lock or
a compression fit configuration, for example. In an embodiment in which a
twist-lock configuration is utilized, the user of infusion pump assembly
400 may first properly position reusable housing assembly 402 with
respect to disposable housing assembly 404 and may then rotate locking
ring assembly 410 (in the direction of arrow 412) to releasably engage
reusable housing assembly 402 with disposable housing assembly 404.
[0385] Through the use of locking ring assembly 410, reusable housing
assembly 402 may be properly positioned with respect to disposable
housing assembly 404 and then releasably engaged by rotating locking ring
assembly 410, thus eliminating the need to rotate reusable housing
assembly 402 with respect to disposable housing assembly 404.
Accordingly, reusable housing assembly 402 may be properly aligned with
disposable housing assembly 404 prior to engagement, and such alignment
may not be disturbed during the engagement process. Locking ring assembly
410 may include a latching mechanism (not shown) that may prevent the
rotation of locking ring assembly 410 until reusable housing assembly 402
and disposable housing assembly 404 are properly positioned with respect
to each other.
[0386] Referring also to FIGS. 16-18, there is shown an
alternative-embodiment infusion pump assembly 500. As with pump assembly
100, 100', infusion pump assembly 500 may include reusable housing
assembly 502 and disposable housing assembly 504.
[0387] In a fashion similar to reusable housing assembly 402, reusable
housing assembly 502 may include a mechanical control assembly (that
includes at least one pump assembly and at least one valve assembly).
Reusable housing assembly 502 may also include an electrical control
assembly that is configured to provide control signals to the mechanical
control assembly and effectuate the delivery of an infusible fluid to a
user. The valve assembly may be configured to control the flow of the
infusible fluid through a fluid path and the pump assembly may be
configured to pump the infusible fluid from the fluid path to the user
[0388] In a fashion similar to disposable housing assembly 404, disposable
housing assembly 504 may be configured for a single use or for use for a
specified period of time, e.g., e.g., three days or any other amount of
time. Disposable housing assembly 504 may be configured such that any
components in infusion pump assembly 500 that come in contact with the
infusible fluid are disposed on and/or within disposable housing assembly
504.
[0389] In this particular embodiment of the infusion pump assembly,
infusion pump assembly 500 may include switch assembly 506 positioned
about the periphery of infusion pump assembly 500. For example, switch
assembly 506 may be positioned along a radial edge of infusion pump
assembly 500, which may allow for easier use by a user. Switch assembly
506 may be covered with a waterproof membrane and/or an o-ring or other
sealing mechanism may be included on the stem 507 of the switch assembly
506 configured to prevent the infiltration of water into infusion pump
assembly 500. However, in some embodiments, switch assembly 506 may
include an overmolded rubber button, thus providing functionality as a
waterproof seal without the use of a waterproof membrane or an o-ring.
However, in still other embodiments, the overmolded rubber button may
additionally be covered by a waterproof membrane and/or include an
o-ring. Reusable housing assembly 502 may include main body portion 508
(housing the above-described mechanical and electrical control
assemblies) and locking ring assembly 510 that may be configured to
rotate about main body portion 508 (in the direction of arrow 512).
[0390] In a fashion similar to reusable housing assembly 402 and
disposable housing assembly 404, reusable housing assembly 502 may be
configured to releasably engage disposable housing assembly 504. Such
releasable engagement may be accomplished by a screw-on, a twist-lock or
a compression fit configuration, for example. In an embodiment in which a
twist-lock configuration is utilized, the user of infusion pump assembly
500 may first properly position reusable housing assembly 502 with
respect to disposable housing assembly 504 and may then rotate locking
ring assembly 510 (in the direction of arrow 512) to releasably engage
reusable housing assembly 502 with disposable housing assembly 404.
[0391] As locking ring assembly 510 included within infusion pump assembly
500 may be taller (i.e., as indicated by arrow 514) than locking ring
assembly 410, locking ring assembly 510 may include a passage 516 through
which button 506 may pass. Accordingly, when assembling reusable housing
assembly 502, locking ring assembly 510 may be installed onto main body
portion 508 (in the direction of arrow 518). Once locking ring assembly
510 is installed onto main body portion 508, one or more locking tabs
(not shown) may prevent locking ring assembly 510 from being removed from
main body portion 508. The portion of switch assembly 506 that protrudes
through passage 516 may then be pressed into main body portion 508 (in
the direction of arrow 520), thus completing the installation of switch
assembly 506.
[0392] Although button 506 is shown in various locations on infusion pump
assembly 500, button 506, in other embodiments, may be located anywhere
desirable on infusion pump assembly 500.
[0393] Through the use of locking ring assembly 510, reusable housing
assembly 502 may be properly positioned with respect to disposable
housing assembly 504 and then releasably engaged by rotating locking ring
assembly 510, thus eliminating the need to rotate reusable housing
assembly 502 with respect to disposable housing assembly 504.
Accordingly, reusable housing assembly 502 may be properly aligned with
disposable housing assembly 504 prior to engagement, and such alignment
may not be disturbed during the engagement process. Locking ring assembly
510 may include a latching mechanism (not shown) that prevents the
rotation of locking ring assembly 510 until reusable housing assembly 502
and disposable housing assembly 504 are properly positioned with respect
to each other. Passage 516 may be elongated to allow for the movement of
locking ring 510 about switch assembly 506.
[0394] Referring also to FIGS. 19A-19B & 20-21, there are shown various
views of infusion pump assembly 500, which is shown to include reusable
housing assembly 502, switch assembly 506, and main body portion 508. As
discussed above, main body portion 508 may include a plurality of
components, examples of which may include but are not limited to volume
sensor assembly 148, printed circuit board 600, vibration motor assembly
602, shape memory actuator anchor 604, switch assembly 506, battery 606,
antenna assembly 608, pump assembly 106, measurement valve assembly 610,
volume sensor valve assembly 612 and reservoir valve assembly 614. To
enhance clarity, printed circuit board 600 has been removed from FIG. 19B
to allow for viewing of the various components positioned beneath printed
circuit board 600.
[0395] The various electrical components that may be electrically coupled
with printed circuit board 600 may utilize spring-biased terminals that
allow for electrical coupling without the need for soldering the
connections. For example, vibration motor assembly 602 may utilize a pair
of spring-biased terminals (one positive terminal and one negative
terminal) that are configured to press against corresponding conductive
pads on printed circuit board 600 when vibration motor assembly 602 is
positioned on printed circuit board 600. However, in the exemplary
embodiment, vibration motor assembly 602 is soldered directly to the
printed circuit board.
[0396] As discussed above, volume sensor assembly 148 may be configured to
monitor the amount of fluid infused by infusion pump assembly 500. For
example, volume sensor assembly 148 may employ acoustic volume sensing,
which is the subject of U.S. Pat. Nos. 5,575,310 and 5,755,683 assigned
to DEKA Products Limited Partnership, as well as the U.S. Patent
Application Publication Nos. US 2007/0228071 A1, US 2007/0219496 A1, US
2007/0219480 A1, US 2007/0219597 A1, the entire disclosures of all of
which are incorporated herein by reference.
[0397] Vibration motor assembly 602 may be configured to provide a
vibration-based signal to the user of infusion pump assembly 500. For
example, in the event that the voltage of battery 606 (which powers
infusion pump assembly 500) is below the minimum acceptable voltage,
vibration motor assembly 602 may vibrate infusion pump assembly 500 to
provide a vibration-based signal to the user of infusion pump assembly
500. Shape memory actuator anchor 604 may provide a mounting point for
the above-described shape memory actuator (e.g. shape memory actuator
112). As discussed above, shape memory actuator 112 may be, for example,
a conductive shape-memory alloy wire that changes shape with temperature.
The temperature of shape-memory actuator 112 may be changed with a
heater, or more conveniently, by application of electrical energy.
Accordingly, one end of shape memory actuator 112 may be rigidly affixed
(i.e., anchored) to shape memory actuator anchor 604 and the other end of
shape memory actuator 112 may be applied to e.g. a valve assembly and/or
a pump actuator. Therefore, by applying electrical energy to shape memory
actuator 112, the length of shape memory actuator 112 may be controlled
and, therefore, the valve assembly and/or the pump actuator to which it
is attached may be manipulated.
[0398] Antenna assembly 608 may be configured to allow for wireless
communication between e.g. infusion pump assembly 500 and remote control
assembly 300 (FIG. 11). As discussed above, remote control assembly 300
may allow the user to program infusion pump assembly 500 and e.g.
configure bolus infusion events. As discussed above, infusion pump
assembly 500 may include one or more valve assemblies configured to
control the flow of the infusible fluid through a fluid path (within
infusion pump assembly 500) and pump assembly 106 may be configured to
pump the infusible fluid from the fluid path to the user. In this
particular embodiment of infusion pump assembly 500, infusion pump
assembly 500 is shown to include three valve assemblies, namely
measurement valve assembly 610, volume sensor valve assembly 612, and
reservoir valve assembly 614.
[0399] As discussed above and referring also to FIG. 21, the infusible
fluid may be stored within reservoir 118. In order to effectuate the
delivery of the infusible fluid to the user, the processing logic (not
shown) included within infusion pump assembly 500 may energize shape
memory actuator 112, which may be anchored on one end using shape memory
actuator anchor 604. Referring also to FIG. 22A, shape memory actuator
112 may result in the activation of pump assembly 106 and reservoir valve
assembly 614. Reservoir valve assembly 614 may include reservoir valve
actuator 614A and reservoir valve 614B, and the activation of reservoir
valve assembly 614 may result in the downward displacement of reservoir
valve actuator 614A and the closing of reservoir valve 614B, resulting in
the effective isolation of reservoir 118. Further, pump assembly 106 may
include pump plunger 106A and pump chamber 106B and the activation of
pump assembly 106 may result in pump plunger 106A being displaced in a
downward fashion into pump chamber 106B and the displacement of the
infusible fluid (in the direction of arrow 616).
[0400] Volume sensor valve assembly 612 may include volume sensor valve
actuator 612A and volume sensor valve 612B. Referring also to FIG. 22B,
volume sensor valve actuator 612A may be closed via a spring assembly
that provides mechanical force to seal volume sensor valve 612B. However,
when pump assembly 106 is activated, if the displaced infusible fluid is
of sufficient pressure to overcome the mechanical sealing force of volume
sensor valve assembly 612, the displacement of the infusible fluid occurs
in the direction of arrow 618. This may result in the filling of volume
sensor chamber 620 included within volume sensor assembly 148. Through
the use of speaker assembly 622, port assembly 624, reference microphone
626, spring diaphragm 628, invariable volume microphone 630, volume
sensor assembly 148 may determine the volume of infusible fluid included
within volume sensor chamber 620.
[0401] Referring also to FIG. 22C, once the volume of infusible fluid
included within volume sensor chamber 620 is calculated, shape memory
actuator 632 may be energized, resulting in the activation of measurement
valve assembly 610, which may include measurement valve actuator 610A and
measurement valve 610B. Once activated and due to the mechanical energy
asserted on the infusible fluid within volume sensor chamber 620 by
spring diaphragm 628, the infusible fluid within volume sensor chamber
620 may be displaced (in the direction of arrow 634) through disposable
cannula 138 and into the body of the user.
[0402] Referring also to FIG. 23, there is shown an exploded view of
infusion pump assembly 500. Shape memory actuator 632 may be anchored (on
a first end) to shape memory actuator anchor 636. Additionally, the other
end of shape memory actuator 632 may be used to provide mechanical energy
to valve assembly 638, which may activate measurement valve assembly 610.
Volume sensor assembly spring retainer 642 may properly position volume
sensor assembly 148 with respect to the various other components of
infusion pump assembly 500. Valve assembly 638 may be used in conjunction
with shape memory actuator 112 to activate pump plunger 106A. Measurement
valve 610B, volume sensor valve 612B and/or reservoir valve 614B may be
self-contained valves that are configured to allow for installation
during assembly of infusion pump assembly 500 by pressing the valves
upward into the lower surface of main body portion 508.
[0403] Referring also to FIG. 24 & FIGS. 25A-25D, there is shown a
more-detailed view of pump assembly 106. Pump actuator assembly 644 may
include pump actuator support structure 646, bias spring 648, and lever
assembly 650.
[0404] Referring also to FIGS. 26A-26B & FIGS. 27A-27B, there is shown a
more-detailed view of measurement valve assembly 610. As discussed above,
valve assembly 638 may activate measurement valve assembly 610.
[0405] Referring also to FIGS. 28A-28D, infusion pump assembly 500 may
include measurement valve assembly 610. As discussed above, valve
assembly 638 may be activated via shape memory actuator 632 and actuator
assembly 640. Accordingly, to infuse the quantity of infusible fluid
stored within volume sensor chamber 620, shape memory actuator 632 may
need to activate valve assembly 638 for a considerable period of time
(e.g. one minute or more). As this would consume a considerable amount of
power from battery 606, measurement valve assembly 610 may allow for the
temporary activation of valve assembly 638, at which point measurement
valve latch 656 may prevent valve assembly 638 from returning to its
non-activated position. Shape memory actuator 652 may be anchored on a
first end using electrical contact 654. The other end of shape memory
actuator 652 may be connected to a valve latch 656. When shape memory
actuator 652 is activated, shape memory actuator 652 may pull valve latch
656 forward and release valve assembly 638. As such, measurement valve
assembly 610 may be activated via shape memory actuator 632. Once
measurement valve assembly 610 has been activated, valve latch 656 may
automatically latch valve assembly 638 in the activated position.
Actuating shape memory actuator 652 may pull valve latch 656 forward and
release valve assembly 638. Assuming shape memory actuator 632 is no
longer activated, measurement valve assembly 610 may move to a
de-activated state once valve latch 656 has released valve assembly 638.
Accordingly, through the use of measurement valve assembly 610, shape
memory actuator 632 does not need to be activated during the entire time
that it takes to infuse the quantity of infusible fluid stored within
volume sensor chamber 620.
[0406] As discussed above, the above-described infusion pump assemblies
(e.g., infusion pumps assemblies 100, 100', 400, 500) may include an
external infusion set 134 configured to deliver the infusible fluid to a
user. External infusion set 134 may include a cannula assembly 136, which
may include a needle or a disposable cannula 138, and tubing assembly 140
which may be also referred to as a tubing set. Tubing assembly 140 may be
in fluid communication with reservoir 118, for example, by way of the
fluid path, and with cannula assembly 138 for example, either directly or
by way of a cannula interface 142.
[0407] Referring also to FIG. 29, there is shown an alternative embodiment
infusion pump assembly 700 that is configured to store a portion of
tubing assembly 140. Specifically, infusion pump assembly 700 may include
peripheral tubing storage assembly 702 that is configured to allow the
user to wind a portion of tubing assembly 140 about the periphery of
infusion pump assembly 700 (in a manner similar to that of a yoyo).
Peripheral tubing storage assembly 702 may be positioned about the
periphery of infusion pump assembly 700. Peripheral tubing storage
assembly 702 may be configured as an open trough into which a portion of
tubing assembly 140 may be wound. Alternatively, peripheral tubing
storage assembly 702 may include one or more divider portions 704, 706
that form a plurality of narrower troughs that may be sized to generate
an interference fit between the walls of the narrower trough and the
exterior surface of the portion of tubing 140. When peripheral tubing
storage assembly 705 includes plurality of divider portions 704, 706, the
resulting narrower troughs may be wound in a spiral fashion about the
periphery of infusion pump assembly 700 (in a manner similar to the
thread of a screw).
[0408] Referring also to FIGS. 30-31, there is shown an alternative
embodiment infusion pump assembly 750 that is configured to store a
portion of tubing assembly 140. Specifically, infusion pump assembly 750
may include peripheral tubing storage assembly 752 that is configured to
allow the user to wind a portion of tubing assembly 140 about the
periphery of infusion pump assembly 750 (again, in a manner similar to
that of a yoyo). Peripheral tubing storage assembly 752 may be positioned
about the periphery of infusion pump assembly 750. Peripheral tubing
storage assembly 752 may be configured as an open trough into which a
portion of tubing assembly 140 is wound. Alternatively, peripheral tubing
storage assembly 752 may include one or more divider portions 754, 756
that form a plurality of narrower troughs that may be sized to generate
an interference fit between the walls of the narrower trough and the
exterior surface of the portion of tubing 140. When peripheral tubing
storage assembly 752 includes plurality of divider portions 754, 756, the
resulting narrower trough may be wound in a spiral fashion about the
periphery of infusion pump assembly 750 (again, in a manner similar to
the thread of a screw).
[0409] Infusion pump assembly 750 may include tubing retainer assembly
758. Tubing retainer assembly 758 may be configured to releasably secure
tubing assembly 140 so as to prevent tubing assembly 140 from unraveling
from around infusion pump assembly 750. In one embodiment of tubing
retainer assembly 758, tubing retainer assembly 758 may include downward
facing pin assembly 760 positioned above upward facing pin assembly 762.
The combination of pin assemblies 760, 762 may define a "pinch point"
through which tubing assembly 140 may be pushed. Accordingly, the user
may wrap tubing assembly 140 around the periphery of infusion pump
assembly 750, wherein each loop of tubing assembly 140 is secured within
peripheral tubing storage assembly 752 via tubing retainer assembly 758.
In the event that the user wishes to lengthen the unsecured portion of
tubing assembly 140, the user may release one loop of tubing assembly 140
from tubing retainer assembly 758. Conversely, in the event that the user
wishes to shorten the unsecured portion of tubing assembly 140, the user
may secure one additional loop of tubing assembly 140 within tubing
retainer assembly 758.
[0410] Referring also to FIGS. 32-33, there is shown an exemplary
embodiment of infusion pump assembly 800. As with infusion pump
assemblies 100, 100', 400, and 500, infusion pump assembly 800 may
include reusable housing assembly 802 and disposable housing assembly
804.
[0411] With reference also to FIGS. 34A-34B, in a fashion similar to
infusion pump assembly 100, reusable housing assembly 802 may be
configured to releasably engage disposable housing assembly 804. Such
releasable engagement may be effectuated by a screw-on, twist-lock, or
compression fit configuration, for example. Infusion pump assembly 800
may include locking ring assembly 806. For example, reusable housing
assembly 802 may be properly positioned relative to disposable housing
assembly, and locking ring assembly 806 may be rotated to releasable
engage reusable housing assembly 802 and disposable housing assembly 804.
[0412] Locking ring assembly 806 may include nub 808 that may facilitate
rotation of locking ring assembly 806. Additionally, the position of nub
808, e.g., relative to tab 810 of disposable housing assembly 804, may
provide verification that reusable housing assembly 802 is fully engaged
with disposable housing assembly 804. For example, as shown in FIG. 34A,
when reusable housing assembly 802 is properly aligned with disposable
housing assembly 804, nub 808 may be aligned in a first position relative
to tab 810. Upon achieving a fully engaged condition, by rotation locking
ring assembly 806, nub 808 may be aligned in a second position relative
to tab 810, as shown in FIG. 34B.
[0413] Referring also to FIGS. 35A-35C and FIGS. 36-38A, in a fashion
similar to reusable housing assembly 102, reusable housing assembly 802
may include mechanical control assembly 812 (e.g., which may include
valve assembly 814, shown in FIG. 36, including one or more valves and
one or more pumps for pumping and controlling the flow of the infusible
fluid). Reusable housing assembly 802 may also include an electrical
control assembly 816 that may be configured to provide control signals to
the mechanical control assembly 812 to effectuate the delivery of an
infusible fluid to the user. Valve assembly 814 may be configured to
control the flow of the infusible fluid through a fluid path and the pump
assembly may be configured to pump the infusible fluid from the fluid
path to the user.
[0414] Mechanical control assembly 812 and electrical control assembly 816
may be contained within a housing defined by base plate 818, body 820. In
some embodiments one or more of base plate 818 and body 820 may provide
electromagnetic shielding. In such an embodiment, the electromagnetic
shielding may prevent and/or reduce electromagnetic interference received
by electrical control assembly 816 and/or created by electrical control
assembly 816. Additionally/alternatively, EMI shield 822 may be included,
as shown in FIG. 36 and FIG. 37. EMI shield 822 may provide shielding
against generated and/or received electromagnetic interference.
[0415] Reusable housing assembly 802 may include a switch assembly that
may be configured to receive user commands (e.g., for bolus delivery,
pairing with a remote control assembly, or the like). The switch assembly
may include button 824 that may be disposed in opening 826 of body 820.
As shown, e.g., in FIG. 35B, locking ring assembly 806 may include radial
slot 828 that may be configured to allow locking ring assembly 806 to be
rotated relative to body 820 while still providing facile access to
button 824.
[0416] Referring also to FIGS. 39A-39C, electrical control assembly 816
may include printed circuit board 830 as well as battery 832. Printed
circuit board 830 may include the various control electronics for
monitoring and controlling the amount of infusible fluid that has been
and/or is being pumped. For example, electrical control assembly 816 may
measure the amount of infusible fluid that has just been dispensed, and
determine, based upon the dosage required by the user, whether enough
infusible fluid has been dispensed. If not enough infusible fluid has
been dispensed, electrical control assembly 816 may determine that more
infusible fluid should be pumped. Electrical control assembly 816 may
provide the appropriate signal to mechanical control assembly 812 so that
any additional necessary dosage may be pumped or electrical control
assembly 816 may provide the appropriate signal to mechanical control
assembly 812 so that the additional dosage may be dispensed with the next
dosage. Alternatively, if too much infusible fluid has been dispensed,
electrical control assembly 816 may provide the appropriate signal to
mechanical control assembly 812 so that less infusible fluid may be
dispensed in the next dosage. Electrical control assembly 816 may include
one or more microprocessors. In an exemplary embodiment, electrical
control assembly 816 may include three microprocessors. One processor
(e.g., which may include, but is not limited to a CC2510
microcontroller/RF transceiver, available from Chipcon AS, of Oslo,
Norway) may be dedicated to radio communication, e.g., for communicating
with a remote control assembly. Two additional microprocessors (example
of which may include, but is not limited to an MSP430 microcontroller,
available from Texas Instruments Inc. of Dallas, Tex.) may be dedicated
to issuing and carrying out commands (e.g., to dispense a dosage of
infusible fluid, process feedback signals from a volume measurement
device, and the like).
[0417] As shown in FIG. 35C, base plate 818 may provide access to
electrical contacts 834, e.g., which may be electrically coupled to
electrical control assembly 816 for recharging battery 832. Base plate
818 may include one or more features (e.g., openings 836, 838) which may
be configured to facilitate proper alignment with disposable housing
assembly 804 by way of cooperating features (e.g., tabs) of disposable
housing assembly 804. Additionally, as shown in FIGS. 40A-40C, 41A-41B,
and 42A-42C, base plate 818 may include various features for mounting
valve assembly 814 and electrical control assembly 816, as well as
providing access to disposable housing assembly 804 by valve assembly
814.
[0418] Locking ring assembly 806 may include grip inserts 840, 842, e.g.,
which may include an elastomeric or textured material that may facilitate
gripping and twisting locking ring assembly 806, e.g., for
engaging/disengaging reusable housing assembly 802 and disposable housing
assembly 804. Additionally, locking ring assembly 806 may include a
sensing component (e.g., magnet 844) that may interact with a component
of reusable housing assembly 802 (e.g., a Hall Effect sensor), e.g., to
provide an indication of the nature of a mating component (e.g., which in
some embodiments may include, but is not limited to, one or more of
disposable housing assembly 804, a charging station, or a filling
station) and/or of whether reusable housing assembly 802 is properly
engaged with the mating component. In the exemplary embodiment, a Hall
Effect sensor (not shown) may be located on the pump printed circuit
board. The Hall Effect sensor may detect when the locking ring has been
rotated to a closed position. Thus, the Hall Effect sensor together with
magnet 844 may provide a system for determining whether the locking ring
has been rotated to a closed position.
[0419] The sensing component (magnet) 844 together with the reusable
housing assembly components, i.e., in the exemplary embodiment, the Hall
Effect sensor, may work to provide for a determination of whether the
reusable housing assembly is properly attached to the intended component
or device. Locking ring assembly 806 may not turn without being attached
to a component, i.e., disposable housing assembly 804, a dust cover or a
charger. Thus, the sensing component together with the reusable housing
assembly component may function to provide many advantageous safety
features to the infusion pump system. These features may include, but are
not limited to, one or more of the following. Where the system does not
detect being attached to a disposable assembly, a dust cover or a
charger, the system may notify, alert or alarm the user as the reusable
portion, e.g., the valves and pumping components, may be vulnerable to
contamination or destruction which may compromise the integrity of the
reusable assembly. Thus, the system may provide for an integrity alarm to
alert the user of potential reusable integrity threats. Also, where the
system senses the reusable assembly is attached to a dust cover, the
system may power off or reduce power to conserve power. This may provide
for more efficient use of power where the reusable assembly is not
connecting to a component in which it needs to interact.
[0420] Referring also now to FIGS. 136-139, in some embodiments, in
addition to the sensing component, a mechanical audible, or "click",
indication may indicate that the reusable housing assembly 2972 is fully
attached to the disposable housing assembly 2976. In some embodiments,
the latching mechanism shown and described above, for example, with
respect to FIG. 38A, may include a spring 2982 actuated tab 2980
assembly. In some embodiments, the tab 2980 includes the sensing
component, which, in some embodiments, may be a magnetic 2986. Referring
now also to FIG. 137, a cross section view at "A" is shown of the
reusable housing assembly 2972 above the disposable housing assembly 2974
in the "unlocked" position. In some embodiments, the "locked" and
"unlocked" position may also be visually indicated to a user/patient
using icons 2976, 2978 that may be molded, etched and/or printed on the
disposable housing assembly 2974, indicating whether the reusable housing
assembly 2972, or, in some embodiments, a fill adapter, is in a locked or
unlocked relationship with the disposable housing assembly 2974 (or, in
some embodiments, the same or similar icons may appear on the dust
cover). In various embodiments, the icons 2976, 2978 may be any form that
may indicate "locked" and "unlocked", or a similar indication, to aid in
the user/patient's understanding of the orientation/position between the
reusable housing assembly 2972 and the disposable housing assembly 2974
(or the dust cover). As shown, the reusable housing assembly 2972 is
aligned about the disposable housing assembly 2974 in an unlocked
orientation. Referring now also to FIG. 138, a cross section view at "A"
is shown of the reusable housing assembly 2972 attached to the disposable
housing assembly 2974 in the unlocked orientation/position is shown. The
tab 2080 is in the unlocked position. Referring now to FIG. 139, a cross
section view at "A" is shown of the reusable housing assembly 2972
attached to the disposable housing assembly 2974 in the locked
orientation/position is shown. As may be seen, the tab 2980 has moved
towards the disposable housing assembly 2974, leaving a space 2984 above
the tab 2980 in the reusable housing assembly 2972. When the tab 2980
moves from the unlocked position (shown in FIG. 138) to the locked
position (shown in FIG. 139) in some embodiments, an audible "click"
sound, and tactile "click", may be detected by the user/patient. This may
be beneficial for many reasons including that the user/patient may only
hear the audible "click" sound if the reusable housing assembly 2972 and
the disposable housing assembly 2974 (or, the dust cover or charger in
various embodiments) are in the correct orientation and fully locked
arrangement. This may ensure the user/patient that the infusion pump
assembly is in the correct and fully locked position. Thus, in various
embodiments where an audible "click" may be heard upon the disposable
housing assembly 2974 and reusable housing assembly 2972 being attached,
the infusion pump assembly will include two safety checks that they are
fully locked: 1) the sensing component described and discussed above; and
2) the audible "click" mechanical component. In various embodiments the
disposable housing assembly 2974 may include a ramp feature that the tab
2980 assembly rides on as the reusable housing assembly 2972 is rotated
from an unlocked to a locked position with respect to the disposable
housing assembly 2974. At the end of the ramp, in some embodiments, an
indentation or relief in the disposable housing assembly 2974 allows the
tab 2980, actuated by the spring 2982, to "click" into the
indentation/relief. Other embodiments allowing for an audible and or
tactile indication to the user/patient may be used in various
embodiments.
[0421] Reusable housing assembly 802 may attach to a number of different
components, including but not limited to, a disposable housing assembly,
a dust cover or a battery charger/battery charging station. In each case,
the Hall Effect sensor may detect that the locking ring is in the closed
position, and therefore, that reusable housing assembly 802 is releasably
engaged to a disposable housing assembly, a dust cover, or a battery
charger/battery charging station (or, another component). The infusion
pump system may determine the component to which it is attached by using
the AVS system (which may also be referred to as the volume measurement
sensor) described in more detail below or by an electronic contact.
Referring now also to FIGS. 38B-38D, one embodiment of a dust cover
(e.g., dust cover 839) is shown. In the exemplary embodiment, dust cover
839 may include features 841, 843, 845, 847 such that the locking ring of
reusable housing assembly 802 may releasably engage dust cover 839. In
addition, dust cover 839 may further include recess region 849 for
accommodating the valving and pumping features of reusable housing
assembly 804. Referring also to FIGS. 140A-140D, in some embodiments,
various embodiments of the dust cover 839, 2988 may include a sealing
assembly 2990 that may be over molded to provide for a complete seal of
the dust cover 839, 2988 to the reusable housing assembly 2972. As shown
in FIG. 140D, where a cut-away cross-sectional view of section D in FIG.
140C, the sealing assembly 2990 is over molded. Additionally, as may be
seen in FIGS. 140A and 140B, in some embodiments of the dust cover 2988,
the dust cover 2988 may include icons 2976, 2978. As discussed above, the
icons 2976, 2978, may be molded, etched and/or printed onto the dust
cover 2988 and may be any form that may indicate "locked" and "unlocked",
or a similar indication, to aid in the user/patient's understanding of
the orientation/position between the reusable housing assembly 2972 and
the dust cover 2988 and/or indicating whether the reusable housing
assembly 2972 is in a locked or unlocked position with respect to the
dust cover 2988. For example, with respect to the dust cover, the AVS
system may determine that a dust cover, and not a disposable housing
assembly, is connected to the reusable housing assembly. The AVS system
may distinguish using a look-up table or other comparative data and
comparing the measurement data with characteristic dust cover or empty
disposable housing assembly data. With respect to the battery charger,
the battery charger, in the exemplary embodiments, may include electric
contacts. When the reusable housing assembly is attached to the battery
charger, the infusion pump assembly electronic system may sense that the
contacts have been made, and will thus indicate that the reusable housing
assembly is attached to a battery charger.
[0422] Referring also to FIGS. 43A-45B and FIGS. 44A-44C an embodiment of
valve assembly 814, which may include one or more valves and one or more
pumps, is shown. As with infusion pump assemblies 100, 100', 400, and
500, valve assembly 814 may generally include reservoir valve 850,
plunger pump 852, volume sensor valve 854, and measurement valve 856.
Similar to the previous description, reservoir valve 850 and plunger pump
852 may be actuated by shape memory actuator 858, which may be anchored
(on a first end) to shape memory actuator anchor 860. Additionally,
measurement valve 856 may be actuated, via valve actuator 862, by shape
memory actuator 864, which may be anchored (on a first end) to shape
memory actuator anchor 866. In a similar manner as discussed above,
measurement valve may be maintained in an open position via measurement
valve latch assembly 868. Measurement valve 856 may be released via
actuation of shape memory actuator 870, which may be anchored (on a first
end) by shape memory actuator anchor 872. In some embodiments, shape
memory actuator anchor 860 may be potted onto the reusable housing
assembly. Using this process during manufacture ensures shape memory
length actuator 858 is installed and maintains the desired length and
tension/strain.
[0423] Referring also to FIGS. 45A-45B and FIGS. 46A-46E, shape memory
actuator 858 (e.g., which may include one or more shape memory wires) may
actuate plunger pump 852 via actuator assembly 874. Actuator assembly 874
may include bias spring 876 and lever assembly 878. Actuator assembly 874
may actuate both plunger pump 852 and measurement valve 850.
[0424] Referring also to FIGS. 47A-47B, measurement valve 856 may be
actuated by shape memory actuator 864, via valve actuator 862 and lever
assembly 878. Once actuated, measurement valve latch assembly 868 may
maintain measurement valve 856 in an open position. Measurement valve
latch assembly 868 actuated by shape memory actuator 870 to release
measurement valve 856, allowing it to return to a closed position.
[0425] Disposable housing assembly 804 may be configured for a single use
or for use for a specified period of time, e.g., e.g., three days or any
other amount of time. Disposable housing assembly 804 may be configured
such that any of the component of infusion pump assembly 800 that come in
contact with the infusible fluid may be disposed on and/or within
disposable housing assembly 804. As such, the risk of contaminating the
infusible fluid may be reduced.
[0426] Referring also to FIG. 48 and FIGS. 49A-49C, disposable housing
assembly 804 may include base portion 900, membrane assembly 902, and top
portion 904. Base portion 900 may include recess 906 that together with
membrane assembly 902 defines reservoir 908 for receiving an infusible
fluid (not shown), e.g., insulin. Referring also to FIGS. 50A-50C, recess
906 may be at least partially formed by and integral with base portion
900. Membrane assembly 902 may be sealingly engaged with base portion
900, e.g., by being compressively pinched between base portion 900 and
top portion 904. Top portion 904 may be attached to base portion 900 by
conventional means, such as gluing, heat sealing, ultrasonic welding, and
compression fitting. Additionally/alternatively, membrane assembly 902
may be attached to base portion 900, e.g., via gluing, ultrasonic
welding, heat sealing, and the like, to provide a seal between membrane
assembly 902 and base portion 900.
[0427] Referring also to FIGS. 141A-141B, an embodiment of the disposable
housing assembly 2974 is shown without the top portion or membrane
assembly. Referring to FIG. 141B, a magnified cut away view of the pump
chamber 106B as indicated by "B" in FIG. 141A is shown. In some
embodiments, a groove 2992 is included on the wall of the pump chamber.
In some embodiments, the groove may allow fluid to flow while the pump
plunger 106A is fully actuated, thus, preventing the pump plunger 106A
from sealing flow out of the pump chamber 106B. FIGS. 142B and 142C are
cross sectional views of FIG. 142A taken at section "B" and "C"
respectively. The groove 2992 may be seen in the pump chamber 106B.
[0428] Referring also to FIGS. 143A-143B, in some embodiments of the
disposable housing assembly 2974, the disposable housing assembly 2974
may include at least one vent 2994 which, in some embodiments, may
include a filter 2996, which may, in some embodiments, be a hydrophobic
filter, which may be, in some embodiments, be a 10 micron filter made
from POREX PM 1020 MUPOR micro porous PTFE membrane, however, in other
embodiments may be a different sized or type of filter for example, a 5
micron, 15 microns, filter and/or a GORTEX filter.
[0429] Still referring to FIGS. 48 and 50A, recess 906, in the exemplary
embodiment, includes raised portion 901 which includes area 903 about
fluid openings 905 leading to the fluid line. Raised portion 901, in the
exemplary embodiment, extends about the perimeter of recess 906. However,
in other embodiments, raised portion 901 may not extend the entire
perimeter, but may be partially about the perimeter. Area 903 about fluid
openings 905 may be shaped as shown in the exemplary embodiment,
including an angled portion, which in some embodiments, includes 45
degree angles, however in other embodiments, the angle may be greater or
lesser. In some embodiments, the pump may not generate a sufficient
enough vacuum to collapse the reservoir so as to eliminate the entire
volume of fluid that may be stored in the reservoir. Raised portion 901
may act to minimize wasted fluid.
[0430] Fluid openings 905, which, in the exemplary embodiment, may include
three openings, however, in other embodiments may include more openings
or fewer openings, may be surrounded by area 903 of the raised portion.
In the exemplary embodiment, fluid openings 905 may be narrow in the
center, thus creating a surface tension that may prevent the air from
being drawn into the opening. In the exemplary embodiment, this area may
be designed to encourage any air that is present in the reservoir to be
drawn above one of fluid openings 905 rather than be pulled through fluid
openings 905 and into the fluid line. Additionally, because there may be
more than one fluid opening 905, where an air bubble is caught above one,
the air may not prevent fluid from flowing through the other two
openings.
[0431] Referring also to FIGS. 144A-144E, another embodiment of the
disposable housing assembly 2974 is shown. In these embodiments, and as
may be seen in FIG. 144B, showing a magnified sectional view of section
"B" as indicated in FIG. 144A, and as may be seen in FIG. 144D, showing a
magnified sectional view of section "D" as indicated in FIG. 144C, and
FIG. 144E is an illustration of the bubble trap, a bubble trap 2998 and
raised area 3000, as well as a radius 3006 and a relief for the septum
3016 are included in the reservoir 3002. In this embodiment, the bubble
trap 2998 is located about the perimeter of the reservoir 3002 wall and
the radius 3006. However, in the area of the raised area 3000, the bubble
trap 2998 includes an outlet section. In the non-outlet section of the
perimeter of the reservoir 3002, the bubble trap 2998 includes
essentially two portions, a taper portion 3008, which tapers to a bottom
portion 3010. In the outlet section, the taper portion 3008 ends, shown
as the end of the taper portion 3014, and the bottom portion 3010
continues in an upward ramp portion 3012 to the reservoir outlet 3004.
The reservoir 3002 includes a membrane (not shown) which forms, together
with the raised area 3000 and the upward ramp portion 3012, essentially a
"tunnel" between the membrane and the fluid outlet.
[0432] As the fluid in the reservoir is pumped out of the reservoir, the
membrane (not shown) moves towards the reservoir wall 3002. In the
embodiments shown in FIGS. 144A-144D, the fluid tends to congregate in
bottom portion 3010 of the bubble trap 2998 and air bubbles do not.
Rather, to the extent air is present, air bubbles tend to congregate in
taper portion 3008 of the bubble trap 2998. At the raised area 3000,
where the taper portion 3008 of the bubble trap 2998 ends at the end of
the taper portion 3014, bubbles, to the extent present, will not likely
enter into the upward ramp portion 3012, and thus, will not likely be
pumped through the exit of the reservoir 3004.
[0433] Thus, as the fluid is pumped through the exit of the reservoir
3004, air is not pulled through the exit of the reservoir 3004. The
embodiments shown in FIGS. 144A-144D may be beneficial for many reasons,
including but not limited to, decreasing air that is pumped from the
reservoir 3002 and into the fluid path in the disposable housing assembly
2974. As air bubbles have a greater surface tension than fluid, the
bubbles will not tend to congregate in the bottom portion 3010 of the
bubble trap 2998, and further, will not tend to flow passed the end of
the taper portion 3014 and onto the upward ramp portion 3012 and through
the exit of the reservoir 3004.
[0434] Referring also to FIGS. 51A-51C, disposable housing assembly 804
may also include fluid pathway cover 910. Fluid pathway cover 910 may be
received in cavity 912 formed on/within base portion 900. Fluid pathway
cover 910 may, in some embodiments, include at least a portion of one or
more channels (e.g., channel 914). The channels included in fluid pathway
cover 910 may fluidly couple one or more volcano valve features (e.g.
volcano valves 916) included on base portion 900. Volcano valves 916 may
include a protrusion having an opening extending through it.
Additionally, fluid pathway cover 910 and base portion 900 may each
define a portion of recess (e.g., recess portions 918, 920 included in
base portion 900 and fluid pathway cover 910 respectively) for fluidly
coupling to an infusion set (e.g., including cannula 922). Cannula 922
may be coupled to disposable housing assembly 804 by conventional means
(e.g., gluing, heat sealing, compression fit, or the like). The fluid
pathways defined by fluid pathway cover 910 and the volcano valves (e.g.,
volcano valves 916) of base portion 900 may define a fluid pathway
between reservoir 908 and cannula 922 for the delivery of the infusible
fluid to the user via the infusion set. However, in some embodiments,
fluid path cover 910 may include at least a portion of the fluid path,
and in some embodiments, fluid path cover 910 may not include at least a
portion of the fluid path. In the exemplary embodiment, fluid pathway
cover 910 may be laser welded to base portion 900. However, in other
embodiments, fluid pathway cover 910 may also be connected to base
portion 900 by conventional means (e.g., gluing, heat sealing, ultrasonic
welding, compression fit, or the like) to achieve a generally fluid tight
seal between fluid pathway cover 910 and base portion 900.
[0435] With reference also to FIGS. 54A-54C, disposable housing assembly
804 may further include valve membrane cover 924. Valve membrane cover
924 may be at least partially disposed over the volcano valves (e.g.,
volcano valve 916) and pumping recess 926 included on/within base portion
900. Valve membrane cover 924 may include a flexible material, e.g.,
which may be selectively engaged against the volcano valves by reservoir
valve 850, volume sensor valve 854, and measurement valve 856 of reusable
housing assembly 802, e.g., for controlling the flow of the infusible
fluid. Additionally, valve membrane cover 924 may be resiliently deformed
into pumping recess 926 by plunger pump 852 to effectuate pumping of the
infusible fluid. Valve membrane cover 924 may be engaged between base
portion 900 and top portion 904 of disposable housing assembly 804 to
form seal 928 between valve membrane cover 924 and base portion 900. For
example, in the exemplary embodiment, valve membrane cover 924 may be
overmolded onto base portion 900. In other embodiment, valve membrane
cover 924 may be compressively pinched between base portion 900 and top
portion 904 to form seal 928. Additionally/alternatively, valve membrane
insert may be connected to one or more of base portion 900 and top
portion 904, e.g., by gluing, heat sealing, or the like.
[0436] Referring also to FIGS. 53A-C, top portion 904 may include
alignment tabs 930, 932 that may be configured to be at least partially
received in openings 836, 838 of base plate 818 of reusable housing
assembly 802 to ensure proper alignment between reusable housing assembly
802 and disposable housing assembly 804. Additionally, top portion 904
may include one or more radial tabs 934, 936, 938, 940 configured to be
engaged by cooperating tabs 942, 944, 946, 948 of locking ring assembly
806. The one or more radial tabs (e.g., radial tab 940) may include stops
(e.g., alignment tab stop 950, which may be used for welding, it's the
tab that fits in the recess to locate and ultrasonically weld), e.g.,
which may prevent further rotation of locking ring assembly 806 once
reusable housing assembly 802 and disposable housing assembly 804 are
fully engaged.
[0437] As discussed above, valve membrane insert 924 may allow for pumping
and flow of the infusible fluid by reservoir valve 850, plunger pump 852,
volume sensor valve 854, and measurement valve 856. Accordingly, top
portion 904 may include one or more openings (e.g., openings 952, 954,
956) that may expose at least a portion of valve membrane insert 924 for
actuation by reservoir valve 850, plunger pump 852, volume sensor valve
854, and measurement valve 856. Additionally, top portion 904 may include
one or more openings 958, 960, 962 which may be configured to allow the
fill volume to be controlled during filling of reservoir 908, as will be
discussed in greater detail below. Reservoir assembly 902 may include
ribs 964, 966, 968 (e.g., as shown in FIG. 52A), which may be at least
partially received in respective openings 958, 960, 962. As will be
described in greater detail below, a force may be applied to one or more
of ribs 964, 966, 968 to, at least temporarily, reduce the volume of
reservoir 908.
[0438] In some embodiments, it may be desirable to provide a seal between
reusable housing assembly 802 and disposable housing assembly 804.
Accordingly, disposable housing assembly 804 may include sealing assembly
970. Sealing assembly 970 may include, for example, an elastomeric member
that may provide a compressible rubber or plastic layer between reusable
housing assembly 802 and disposable housing assembly 804 when engaged,
thus preventing inadvertent disengagement and penetration by outside
fluids. For example, sealing assembly 970 may be a watertight seal
assembly and, thus, enable a user to wear infusion pump assembly 800
while swimming, bathing or exercising.
[0439] In a fashion similar to, e.g., disposable housing assembly 114,
disposable housing assembly 802 may, in some embodiments, be configured
to have reservoir 908 filled a plurality of times. However, in some
embodiments, disposable housing assembly 114 may be configured such that
reservoir 908 may not be refilled. Referring also to FIGS. 57-64, fill
adapter 1000 may be configured to be coupled to disposable housing
assembly 804 for refilling reservoir 908 using a syringe (not shown).
Fill adapter 1000 may include locking tabs 1002, 1004, 1006, 1008 that
may be configured to engage radial tabs 934, 936, 938, 940 of disposable
housing assembly 804 in a manner generally similar to tabs 942, 944, 946,
948 of locking ring assembly 806. Accordingly, fill adapter 1000 may be
releasably engaged with disposable housing assembly 804 by aligning fill
adapter 1000 with disposable housing assembly 804 and rotating fill
adapter 1000 and disposable housing assembly 804 relative to one another
to releasably engage locking tabs 1002, 1004, 1006, 1008 with radial tabs
934, 936, 938, 940.
[0440] Fill adapter 1000 may further include filling aid 1010, which may
include guide passage 1012, e.g., which may be configured to guide a
needle of a syringe (not shown) to a septum of disposable housing
assembly 804 to allow reservoir 908 of disposable housing assembly 804 to
be filled by the syringe. In some embodiments, guide passage 1012 may be
an angled bevel or other gradual angled bevel to further guide a syringe
to a septum. Fill adapter 1000 may facilitate filling reservoir 908 by
providing a relatively large insertion area, e.g., at the distal opening
of guide passage 1012. Guide passage 1012 may generally taper to a
smaller proximal opening that may be properly aligned with the septum of
disposable housing assembly 804, when fill adapter 1000 is engaged with
disposable housing assembly 804. Accordingly, fill adapter 1000 may
reduce the dexterity and aim necessary to properly insert a needle
through the septum of disposable housing assembly 804 for the purpose of
filling reservoir 908.
[0441] As discussed above, disposable housing assembly 804 may configured
to facilitate controlling the quantity of infusible fluid delivered to
reservoir 908 during filling. For example, membrane assembly 902 of
disposable housing assembly 804 may include ribs 964, 966, 968 that may
be depressed and at least partially displaced into reservoir 908, thereby
reducing the volume of reservoir 908. Accordingly, when infusible fluid
is delivered to reservoir 908, the volume of fluid that may be
accommodated by reservoir 908 may be correspondingly reduced. Ribs 964,
966, 968 may be accessible via openings 958, 960, 962 in top portion 904
of disposable housing assembly 804.
[0442] Fill adapter 1000 may include one or more button assemblies (e.g.,
button assemblies 1014, 1016, 1018) corresponding to ribs 964, 966, 968.
That is, when fill adapter 1000 is releasably engaged with disposable
housing assembly 804, buttons 1014, 1016, 1018 may be aligned with ribs
964, 966, 968. Button assemblies 1014, 1016, 1018 may be, for example,
cantilever members capable of being depressed. When fill adapter 1000 is
releasably engaged with disposable housing assembly 804, one or more of
button assemblies 1014, 1016, 1018 may be depressed, and may
correspondingly displace a respective one of ribs 964, 966, 698 into
reservoir 908, causing an attendant reduction in the volume of reservoir
908.
[0443] For example, assume for illustrative purposes that reservoir 908
has a maximum capacity of 3.00 mL. Further, assume that button assembly
1014 is configured to displace rib 964 into disposable housing assembly
804, resulting in a 0.5 mL reduction in the 3.00 mL capacity of
disposable housing assembly 804. Further, assume that button assembly
1016 is configured to displace rib 966 into disposable housing assembly
804, also resulting in a 0.5 mL reduction in the 3.00 mL capacity of
disposable housing assembly 804. Further, assume that button assembly
1018 is configured to displace slot assembly 968 into disposable housing
assembly 804, also resulting in a 0.5 mL reduction in the 3.00 mL
capacity of disposable housing assembly 804. Therefore, if the user
wishes to fill reservoir 908 within disposable housing assembly 804 with
2.00 mL of infusible fluid, in some embodiments, the user may first fill
the reservoir to the 3.00 mL capacity and then depresses button
assemblies 1016 and 1014 (resulting in the displacement of rib 966 into
disposable housing assembly 804), effectively reducing the 3.00 mL
capacity of reservoir 908 within disposable housing assembly 804 to 2.00
mL. In some embodiments, the user may first depress a respective number
of button assemblies, effectively reducing the capacity of reservoir 908,
and then fill reservoir 908. Although a particular number of button
assemblies are shown, representing the exemplary embodiment, in other
embodiments, the number of button assemblies may vary from a minimum of 1
to as many as is desired. Additionally, although for descriptive
purposes, and in the exemplary embodiment, each button assembly may
displace 0.5 mL, in other embodiments, the volume of displacement per
button may vary. Additionally, the reservoir may be, in various
embodiments, include a larger or smaller volume than described in the
exemplary embodiment.
[0444] According to the above-described configuration, the button
assemblies (e.g., button assemblies 1014, 1016, 108) may employed, at
least in part, to control the fill volume of reservoir 908. By not
depressing any of the button assemblies, the greatest fill volume of
reservoir 908 may be achieved. Depressing one button assembly (e.g.,
button assembly 1014) may allow the second greatest fill volume to be
achieved. Depressing two button assemblies (e.g., button assemblies 1014,
1016) may achieve the third greatest fill volume. Depressing all three
button assemblies (e.g., button assemblies 1014, 1016, 1018) may allow
the smallest fill volume to be achieve.
[0445] Further, in an embodiment button assemblies 1014, 1016, 1018 may be
utilized, at least in part, to facilitate filling of reservoir 908. For
example, once a filling needle (e.g., which may be fluidly coupled to a
vial of infusible fluid) has been inserted into reservoir 908, button
assemblies 1014, 1016, 1018 may be depressed to pump at least a portion
of any air that may be contained within reservoir into the vial of
infusible fluid. Button assemblies 1014, 1016, 1018 may subsequently be
released to allow infusible fluid to flow from the vial into reservoir
908. Once reservoir 908 has been filled with the infusible fluid, one or
more button assemblies (e.g., one or more of button assemblies 1014,
1016, 1018) may be depressed, thereby squeezing at least a portion of the
infusible fluid from reservoir 908 (e.g., via a needle used to fill
reservoir 908 and back into the vial of infusible fluid). As discussed
above, the volume of infusible fluid contained within reservoir 908 may
be controlled, e.g., depending upon how many button assemblies are
depressed (e.g., which may control how much infusible fluid is squeezed
back into the vial of infusible fluid).
[0446] With particular reference to FIGS. 62-64, filling aid 1010 may be
pivotally coupled to fill adapter base plate 1020. For example, filling
aid 1010 may include pivot members 1022, 1024 that may be configured to
be received in pivot supports 1026, 1028, thereby allowing filling aid to
pivot between an open position (e.g., as shown in FIGS. 57-61) and a
closed position (e.g., as shown in FIGS. 63-64). The closed position may
be suitable, e.g., for packaging fill adapter 1000, storage of fill
adapter 1000, or the like. In order to ensure that filling aid 1010 is
properly oriented for filling reservoir 908, fill adapter 1000 may
include support member 1030. To properly orient filling aid 1010, a user
may pivot filling aid 1010 to a fully open position, wherein filling aid
1010 may contact support member 1030.
[0447] According to an alternative embodiment, and referring also to FIG.
65, fill adapter 1050 may be configured to releasably engage disposable
housing assembly 804 via a plurality of locking tabs (e.g., locking tabs
1052, 1054). Additionally, fill adapter 1050 may include a plurality of
button assemblies (e.g., button assemblies 1056, 1058, 1060) that may
interact with ribs 964, 966, 968 of disposable housing assembly 804 to
adjust a fill volume of reservoir 908. Fill adapter 1050 may further
include filling aid 1062, having guide passage 1064 configured to align a
needle of a syringe with the septum of disposable housing 804, e.g., for
accessing reservoir 908 for the purpose of filling reservoir 908 with an
infusible fluid. Filling aid 1062 may be connected to base plate 1066,
e.g., as an integral component therewith, by gluing, heat sealing,
compression fit, or the like.
[0448] Referring also to FIGS. 66-74, vial fill adapter 1100 may be
configured to facilitate filling reservoir 908 of disposable housing
assembly 804 directly from a vial. Similar to fill adapter 1000, vial
fill adapter 1100 may include locking tabs 1102, 1104, 1106, 1108 that
may be configured to engage radial tabs 934, 936, 938, 940 of disposable
housing assembly in a manner generally similar to tabs 942, 944, 946, 948
of locking ring assembly 806. Accordingly, vial fill adapter 1100 may be
releasably engaged with disposable housing assembly 804 by aligning vial
fill adapter 1100 with disposable housing assembly 804 and rotating vial
fill adapter 1100 and disposable housing assembly 804 relative to one
another to releasably engage locking tabs 1102, 1104, 1106, 1108 with
radial tabs 934, 936, 938, 940.
[0449] As discussed above, disposable housing assembly 804 may be
configured to facilitate controlling the quantity of infusible fluid
delivered to reservoir 908 during filling. For example, membrane assembly
902 of disposable housing assembly 804 may include ribs 964, 966, 968
that may be depressed and at least partially displaced into reservoir
908, thereby reducing the volume of reservoir 908. Accordingly, when
infusible fluid is delivered to reservoir 908, the volume of fluid that
may be accommodated by reservoir 908 may be correspondingly reduced. Ribs
964, 966, 968 may be accessible via openings 958, 960, 962 in top portion
904 of disposable housing assembly 804.
[0450] Vial fill adapter 1100 may include one or more button assemblies
(e.g., button assemblies 1110, 1112, 1114) corresponding to ribs 964,
966, 968 (e.g., shown in FIG. 52A). That is, when vial fill adapter 1100
is releasably engaged with disposable housing assembly 804, buttons 1110,
1112, 1114 may be aligned with ribs 964, 966, 968. Button assemblies
1110, 1112, 1114 may be, for example, cantilever members capable of being
depressed. When vial fill adapter 1100 is releasably engaged with
disposable housing assembly 804, one or more of button assemblies 1110,
1112, 1114 may be depressed, and may correspondingly displace a
respective one of ribs 964, 966, 698 into reservoir 908, thereby reducing
the volume of reservoir 908.
[0451] For example, assume for illustrative purposes that reservoir 908
has a maximum capacity of 3.00 mL. Further, assume that button assembly
1110 is configured to displace rib 964 into disposable housing assembly
804, resulting in a 0.5 mL reduction in the 3.00 mL capacity of
disposable housing assembly 804. Further, assume that button assembly
1112 is configured to displace rib 966 into disposable housing assembly
804, also resulting in a 0.5 mL reduction in the 3.00 mL capacity of
disposable housing assembly 804. Further, assume that button assembly
1114 is configured to displace rib 968 into disposable housing assembly
804, also resulting in a 0.50 mL reduction in the 3.00 mL capacity of
disposable housing assembly 804. Therefore, if the user wishes to fill
reservoir 908 within disposable housing assembly 804 with 2.00 mL of
infusible fluid, the user may depress button assemblies 1112 and 1114
(resulting in the displacement of ribs 966 and 968 into disposable
housing assembly 804), effectively reducing the 3.00 mL capacity of
reservoir 908 within disposable housing assembly 804 to 2.0 mL.
[0452] Vial fill adapter 1100 may further include vial filling aid
assembly 1116 that may be configured to fluidly couple a vial of
infusible fluid to reservoir 908 of disposable housing assembly 804 via a
septum. With particular reference to FIG. 71, vial filling aid assembly
may include double ended needle assembly 1118. Double ended needle
assembly 1118 may include first needle end 1120 configured to penetrate
the septum of a vial (not shown) and second needle end 1122 configured to
penetrate the septum of disposable housing assembly 804. As such, the
vial and reservoir 908 may be fluidly coupled allowing infusible fluid to
be transferred from the vial to reservoir 908. Double ended needle
assembly 1118 may include vial engagement portion 1124 adjacent first end
1120. Vial engagement arms 1124, 1126 may be configured to releasably
engage, e.g., a vial cap, to assist in maintaining the fluid connection
between double ended needle assembly 1118 and the vial. Additionally,
double ended needle assembly 1118 may include body 1128 that may be
slidably received in opening 1130 of vial filling aid body 1132. Vial
filling aid body 1132 may include stabilizer arms 1134, 1136, e.g., which
may be configured to stabilize the vial during filling of disposable
housing assembly 804. In one embodiment, the vial may be engaged with
double ended needle assembly 1118 e.g., such that first end 1120 may
penetrate the septum of the vial and the cap of the vial may be engaged
by engagement arms 1124, 1126. Body 1128 may be slidably inserted into
opening 1130 such that second end 1122 of double ended needle assembly
1118 may penetrate the septum of disposable body assembly 804.
[0453] Similar to fill adapter 1000, vial filling aid assembly 1116 may be
configured to be pivotally coupled to vial fill adapter base plate 1138.
For example, vial filling aid 1116 may include pivot members 1140, 1142
that may be configured to be received in pivot supports 1144, 1146 (e.g.,
shown in FIG. 71), thereby allowing vial filling aid 1116 to pivot
between an open position (e.g., as shown in FIGS. 66-70) and a closed
position (e.g., as shown in FIGS. 72-74). The closed position may be
suitable, e.g., for packaging vial fill adapter 1100, storage of vial
fill adapter 1100, or the like. In order to ensure that vial filling aid
1116 is properly oriented for filling reservoir 908, vial fill adapter
1100 may include support member 1148. To properly orient vial filling aid
1116, a user may pivot vial filling aid 1116 to a fully open position,
wherein vial filling aid 1116 may contact support member 1148.
Additionally, vial fill adapter base plate 1138 may include one or more
locking features (e.g., locking tabs 1150, 1152) that may engage vial
filing aid 1116, and may maintain vial filling aid 1116 in the closed
position. Vial fill adapter base plate 1138 may also include features
(e.g., tabs 1154, 1156) that may be configured to assist in retaining
double ended needle assembly 1118, e.g., by preventing slidable
separation of double ended needle assembly 1118 from vial filling aid
body 1132.
[0454] As shown in FIGS. 72-74, filling aid assembly 1116 is in a closed
position. In this configuration, support member 1148 may additionally
function as a needle guard. When removing filling aid assembly 1116 from
disposable housing assembly 804, support member 1148 may function to
safely allow a user to squeeze the ends and rotate filling aid assembly
1116 for removal. As shown in FIG. 70, in the open position, support
member 1148 may function as a stop to maintain proper orientation.
[0455] Referring again to FIGS. 57-73, the exemplary embodiments of the
fill adapter include a grip feature (e.g., 1166 in FIG. 72). Grip feature
1166 may provide a grip interface for removal of the fill adapter from
disposable housing assembly 804. Although shown in one configuration in
these figures, in other embodiments, the configuration may vary. In still
other embodiments, a grip feature may not be included.
[0456] According to one embodiment, fill adapter base plate 1020 and vial
fill adapter base plate 1138 may be interchangeable components.
Accordingly, a single base plate (e.g., either fill adapter base plate
1020 or vial fill adapter base plate 1138 may be used with either filling
aid 1010 or vial filling aid 1116. Accordingly, the number of distinct
components that are required for both filling adapters may be reduced,
and a user may have the ability to select the filling adapter that may be
the most suitable for a given filling scenario.
[0457] The various embodiments of the fill adapters may provide many
safely benefits, including but not limited to: providing a system for
filling the reservoir without handling a needle; protecting the reservoir
from unintentional contact with the needle, i.e., destruction of the
integrity of the reservoir through unintentional puncture; designed to be
ambidextrous; in some embodiments, may provide a system for maintaining
air in the reservoir.
[0458] As discussed above, reusable housing assembly 802 may include
battery 832, e.g., which may include a rechargeable battery. Referring
also to FIGS. 75-80, battery charger 1200 may be configured to recharge
battery 832. Battery charger 1200 may include housing 1202 having top
plate 1204. Top plate 1204 may include one or more electrical contacts
1206, generally, configured to be electrically coupled to electrical
contacts 834 of reusable housing assembly 802. Electrical contacts 1206
may include, but are not limited to, electrical contact pads, spring
biased electrical contact members, or the like. Additionally, top plate
1204 may include alignment tabs 1208, 1210, which may be configured to
mate with openings 836, 838 in base plate 818 of reusable housing
assembly 802 (e.g., as shown in FIG. 35C). The cooperation of alignment
tabs 1208, 1210 and openings 836, 838 may ensure that reusable housing
assembly 802 is aligned with battery charger 1200 such that electrical
contacts 1206 of battery charger 1200 may electrically couple with
electrical contacts 834 of reusable housing assembly 802.
[0459] With reference also to FIGS. 77 and 78, battery charger 1200 may be
configured to releasably engage reusable housing assembly 802. For
example, in a similar manner as disposable housing assembly 804, battery
charger 1200 may include one or more locking tabs (e.g., locking tabs
1212, 1214 shown in FIG. 76). The locking tabs (e.g., locking tabs 1212,
1214) may be engaged by tabs 942, 944, 946, 948 of locking ring assembly
806. As such, reusable housing assembly 802 may be aligned with battery
charger 1200 (via alignment tabs 1208, 1210) with locking ring 806 in a
first, unlocked position, as shown in FIG. 77. Locking ring 806 may be
rotated relative to battery charger 1200 in the direction of arrow 1216
to releasably engage tabs 942, 944, 946, 948 of locking ring 806 with the
locking tabs (e.g., locking tabs 1212, 1214) of battery charger 1200, as
shown in FIG. 78.
[0460] In an embodiment, battery charger 1200 may include recessed region
1218, e.g., which may, in the exemplary embodiments, provide clearance to
accommodate reusable housing assembly 802 pumping and valving components.
Referring also to FIGS. 79 & 80, battery charger 1200 may provide
electrical current to electrical contacts 1206 (and thereby to reusable
housing assembly 802 via electrical contacts 834) for recharging battery
832 of reusable housing assembly 802. In some embodiments, when a signal
indicative of a fully engaged reusable housing is not provided, current
may not be provided to electrical contacts 1206. According to such an
embodiment, the risk associated with an electrical short circuit (e.g.,
resulting from foreign objects contacting electrical contacts 1206) and
damage to reusable housing assembly 802 (e.g., resulting from improper
initial alignment between electrical contacts 1206 and electrical
contacts 834) may be reduced. Additionally, battery charger 1200 may not
unnecessarily draw current when battery charger is not charging reusable
housing assembly 802.
[0461] Still referring to FIGS. 79 and 80, battery charger 1200 may
include a lower housing portion 1224 and top plate 1204. Printed circuit
board 1222 (e.g., which may include electrical contacts 1206) may be
disposed within a cavity included between top plate 1204 and lower
housing portion 1224.
[0462] Referring also to FIGS. 81-89B, various embodiments of battery
charger/docking stations are shown. FIGS. 81 and 82 depicts desktop
charger 1250 including recess 1252 configured to mate with and recharge a
reusable housing assembly (e.g., reusable housing assembly 802). The
reusable housing assembly may rest in recess 1252 and or may be
releasably engaged in recess 1252, in a similar manner as discussed
above. Additionally, desktop charger 1250 may include recess 1254
configured to mate with a remote control assembly (e.g., remote control
assembly 300). Recess 1254 may include a USB plug 1256, e.g., which may
be configured to couple with the remote control assembly when the remote
control assembly is disposed within recess 1254. USB plug 1256 may allow
for data transfer to/from the remote control assembly, as well as
charging of remote control assembly. Desktop charger 1250 may also
include USB port 1258 (e.g., which may include a mini-USB port), allowing
desktop charger to receive power (e.g., for charging the reusable housing
assembly and/or the remote control assembly). Additionally/alternatively
USB port 1258 may be configured for data transfer to/from remote control
assembly and/or reusable housing assembly, e.g., by connection to a
computer (not shown).
[0463] Referring to FIGS. 83A-83B, similar to the previous embodiment,
desktop charger 1260 may include recess 1262 for mating with a reusable
housing assembly (e.g., reusable housing assembly 1264). Desktop charger
may also include recess 1266 configured to receive a remote control
assembly (e.g., remote control assembly 1268). One or more of recess
1262, 1266 may include electrical and/or data connections configure to
charge and/or transfer data to/from reusable housing assembly 1262 and/or
remote control assembly 1268, respectively.
[0464] Referring to FIGS. 84A-84B, another embodiment of a desktop charger
is shown. Similar to desktop charger 1260, desktop charger 1270 may
include recesses (not shown) for respectively mating with reusable
housing assembly 1272 and remote control assembly 1274. As shown, desktop
charger 1270 may hold reusable housing assembly 1272 and remote control
assembly 1274 in a side-by-side configuration. Desktop charger 1270 may
include various electrical and data connection configured to charge
and/or transfer data to/from reusable housing assembly 1272 and/or remote
control assembly 1274, as described in various embodiments above.
[0465] Referring to FIG. 85A-85D, collapsible charger 1280 may include
recess 1282 for receiving reusable housing assembly 1284 and remote
control assembly 1286. Collapsible charger 1280 may include various
electrical and data connection configured to charge and/or transfer data
to/from reusable housing assembly 1284 and/or remote control assembly
1286, as described in various embodiments above. Additionally, as shown
in FIGS. 85B-85D, collapsible charger 1280 may include pivotable cover
1288. Pivotable cover 1288 may be configured to pivot between an open
position (e.g., as shown in FIG. 85B), in which reusable housing assembly
1284 and remote control assembly 1286 may be docked in collapsible
charger 1280, and a closed position (e.g., as shown in FIG. 85D), in
which recess 1282 may be covered by pivotable cover 1288. In the closed
position, recess 1282, as well as any electrical and/or data connections
disposed therein, may be protected from damage.
[0466] Referring to FIG. 86, wall charger 1290 may include recess 1292
configured to receive reusable housing assembly 1294. Additionally, wall
charger 1290 may include recess 1296 configured to receive remote control
assembly 1298. Reusable housing assembly 1294 and remote control assembly
1298 may be positioned in a stacked configuration, e.g., thereby
providing a relatively slim profile. A rear portion of wall charger 1290
may include an electrical plug, configured to allow wall charger to be
plugged into an electrical receptacle. As such, wall charger 1290, while
plugged into the electrical receptacle, may achieve a wall mounted
configuration. Additionally, while plugged into the electrical
receptacle, wall charger 1290 may be provided with power for charging
reusable housing assembly 1294 and/or remote control assembly 1298.
[0467] Referring to FIG. 87, wall charger 1300 may include recess 1302
configured to receive remote control assembly 1304. Additionally, wall
charger may include a recess (not shown) configured to receive reusable
housing assembly 1306. Wall charger 1300 may be configured to position
remote control assembly 1304 and reusable housing assembly 1306 in a
back-to-back configuration, which may provide a relatively thin profile.
Additionally, wall charger 1300 may include an electrical plug 1308
configured to be plugged into an electrical receptacle. Electrical plug
1308 may include a stowable configuration, in which electrical plug 1308
may be pivotable between a deployed position (e.g., as shown), and a
stowed position. In the deployed position, electrical plug 1308 may be
oriented to be plugged into an electrical receptacle. In the stowed
position electrical plug 1308 may be disposed within recess 1310, which
may protect electrical plug 1308 from damage and/or from damaging other
items.
[0468] Referring to FIG. 88, charger 1320 may include recess 1322
configured to receive reusable housing assembly 1324. Charger 1320 may
additionally include a recess (not shown) configured to receive remote
control assembly 1326. Charger 1320 may additionally include cover 1328.
Cover 1328 may be configured to pivot between an open position (as shown)
and a closed position. When cover 1328 is in the open position, reusable
housing assembly 1324 and remote control assembly 1326 may be accessible
(e.g., allowing a user to remove/install reusable housing assembly 1324
and/or remote control assembly 1326 from/into charger 1320. When cover
1324 is in the closed position, cover 1328 and charger body 1330 may
substantially enclose reusable housing assembly 1324 and/or remote
control assembly 1326 and/or recess 1322 and the recess configured to
receive remote control assembly 1326, thereby providing damage and/or
tamper protection for reusable housing assembly 1324, remote control
assembly 1326 and/or any electrical and/or data connection associated
with charger 1320.
[0469] Referring to FIGS. 89A-89B, wall charger 1350 may include recess
1352 configured to receive remote control assembly 1354. Wall charger
1350 may also include recess 1356 configured to receive reusable housing
assembly 1358. Wall charger 1350 may be configured to position remote
control assembly 1354 and reusable housing assembly 1358 in a generally
side-by-side configuration, thereby providing a relatively slim profile.
Charger 1350 may additionally include electrical plug 1360, e.g., which
may be configured to be plugged into an electrical receptacle. Electrical
plug 1360 may include a stowable configuration, in which electrical plug
1360 may be pivotable between a deployed position (e.g., as shown), and a
stowed position. In the deployed position, electrical plug 1360 may be
oriented to be plugged into an electrical receptacle. In the stowed
position electrical plug 1360 may be disposed within recess 1362, which
may protect electrical plug 1308 from damage and/or from damaging other
items.
[0470] Infusion pump therapy may include volume and time specifications.
The amount of fluid dispensed together with the dispense timing may be
two critical factors of infusion pump therapy. As discussed in detail
below, the infusion pump apparatus and systems described herein may
provide for a method of dispensing fluid together with a device, system
and method for measuring the amount of fluid dispensed. However, in a
circumstance where the calibration and precision of the measurement
device calibration is critical, there may be advantages to determining
any compromise in the precision of the measurement device as soon as
possible. Thus, there are advantages to off-board verification of volume
and pumping.
[0471] As discussed above, infusion pump assembly 100 may include volume
sensor assembly 148 configured to monitor the amount of fluid infused by
infusion pump assembly 100. Further and as discussed above, infusion pump
assembly 100 may be configured so that the volume measurements produced
by volume sensor assembly 148 may be used to control, through a feedback
loop, the amount of infusible fluid that is infused into the user.
[0472] Referring also to FIGS. 90A-90C, there is shown one diagrammatic
view and two cross-sectional views of volume sensor assembly 148.
Referring also to FIGS. 91A-91I, there is shown various isometric and
diagrammatic views of volume sensor assembly 148 (which is shown to
include upper housing 1400). Referring also to FIGS. 92A-92I, there is
shown various isometric and diagrammatic views of volume sensor assembly
148 (with upper housing 1400 removed), exposing speaker assembly 622,
reference microphone 626, and printed circuit board assembly 830.
Referring also to FIGS. 93A-93I, there is shown various isometric and
diagrammatic views of volume sensor assembly 148 (with printed circuit
board assembly 830 removed), exposing port assembly 624. Referring also
to FIGS. 94A-94F, there is shown various isometric and diagrammatic
cross-sectional views of volume sensor assembly 148 (with printed circuit
board assembly 830 removed), exposing port assembly 624. Referring also
to FIG. 95, there are shown an exploded view of volume sensor assembly
148, exposing upper housing 1400, speaker assembly 622, reference
microphone 626, seal assembly 1404, lower housing 1402, port assembly
624, spring diaphragm 628, and retaining ring assembly 1406.
[0473] The following discussion concerns the design and operation of
volume sensor assembly 148 (which is shown in a simplified form in FIG.
96). For the following discussion, the following nomenclature may be
used:
TABLE-US-00009
Symbols
P Pressure
p Pressure Perturbation
V Volume
.nu. Volume Perturbation
.gamma. Specific Heat Ratio
R Gas Constant
.rho. Density
Z Impedance
f Flow friction
A Cross sectional Area
L Length
.omega. Frequency
.zeta. Damping ratio
.alpha. Volume Ratio
Subscripts
0 Speaker Volume
1 Reference Volume
2 Variable Volume
k Speaker
r Resonant Port
z Zero
p Pole
Derivation of the Equations for Volume Sensor Assembly 148:
[0474] Modeling the Acoustic Volumes
[0475] The pressure and volume of an ideal adiabatic gas may be related
by:
PV.sup..gamma.=K [EQ#1]
[0476] where K is a constant defined by the initial conditions of the
system.
[0477] EQ#1 may be written in terms of a mean pressure, P, and volume, V,
and a small time-dependent perturbation on top of those pressures, p(t),
.nu.(t) as follows:
(P+p(t))(V+.nu.(t)).sup..gamma.=K [EQ#2]
[0478] Differentiating this equation may result in:
{dot over
(p)}(t)(V+.nu.(t)).sup..gamma.+.gamma.(V+.nu.(t)).sup..gamma.-1(P+p(t)){d-
ot over (.nu.)})(t)=0 [EQ#3]
[0479] which may simplify to:
p . ( t ) + .gamma. P + p ( t ) V + v
( t ) v . ( t ) = 0 [ EQ #4 ]
##EQU00001##
[0480] If the acoustic pressure levels are much less than the ambient
pressure, the equation may be further simplified to:
p . ( t ) + .gamma. P V v . ( t ) =
0 [ EQ #5 ] ##EQU00002##
[0481] How good is this assumption? Using the adiabatic relation it may be
shown that:
P V = ( P + p ( t ) V + v ( t ) ) ( P +
p ( t ) P ) - .gamma. + 1 .gamma. [ EQ #6 ]
##EQU00003##
[0482] Accordingly, the error in the assumption would be:
error = 1 - ( P + p ( t ) P ) - .gamma. + 1 .gamma.
[ EQ #7 ] ##EQU00004##
[0483] A very loud acoustic signal (120 dB) may correspond to pressure
sine wave with amplitude of roughly 20 Pascal. Assuming air at
atmospheric conditions (.gamma.=1.4, P=101325 Pa), the resulting error is
0.03%. The conversion from dB to Pa is as follows:
.lamda. = 20 log 10 ( p rm s p ref )
or p r m s = p ref 10 .lamda. 20
[ EQ #8 ] ##EQU00005##
[0484] where p.sub.ref=20.mu.Pa.
[0485] Applying the ideal gas law, P=.rho.RT, and substituting in for
pressure may result in the following:
p . ( t ) + .gamma. RT .rho. V v .
( t ) = 0 [ EQ #9 ] ##EQU00006##
[0486] EQ#9 may be written in terms of the speed of sound, a= {square root
over (.gamma.RT)} as follows:
p . ( t ) + .rho. a 2 V v . ( t )
= 0 [ EQ #10 ] ##EQU00007##
[0487] Acoustic impedance for a volume may be defined as follows:
Z v = p ( t ) v . ( t ) = - 1 ( V .rho.
a 2 ) s [ EQ #11 ] ##EQU00008##
[0488] Modeling the Acoustic Port
[0489] The acoustic port may be modeled assuming that all of the fluid in
the port essentially moves as a rigid cylinder reciprocating in the axial
direction. All of the fluid in the channel is assumed to travel at the
same velocity, the channel is assumed to be of constant cross section,
and the "end effects" resulting from the fluid entering and leaving the
channel are neglected.
[0490] If we assume laminar flow friction of the form .DELTA.p=f .rho.{dot
over (.nu.)}, the friction force acting on the mass of fluid in the
channel may be written as follows:
F=f.rho.A.sup.2{dot over (x)} [EQ#12]
[0491] A second order differential equation may then be written for the
dynamics of the fluid in the channel:
.rho.LA{umlaut over (x)}=.DELTA.pA-f.rho.A.sup.2{dot over (x)} [EQ#13]
[0492] or, in terms of volume flow rate:
v = - fA L v . + .DELTA. p A .rho.
L [ EQ #14 ] ##EQU00009##
[0493] The acoustic impedance of the channel may then be written as
follows:
Z p = .DELTA. p v . = .rho. L A ( s +
f A L ) [ EQ #15 ] ##EQU00010##
[0494] System Transfer Functions
[0495] Using the volume and port dynamics defined above, volume sensor
assembly 148 may be described by the following system of equations:
(k=speaker, r=resonator)
p . 0 - .rho. a 2 V 0 v . k = 0 [
EQ #16 ] p . 1 + .rho. a 2 V 1 (
v . k - v . r ) = 0 [ EQ #17 ] p . 2 +
.rho. a 2 V 2 v . r = 0 [ EQ #18 ]
v r = - fA L v . r + A .rho. L ( p
2 - p 1 ) [ EQ #19 ] ##EQU00011##
[0496] One equation may be eliminated if p.sub.0 is treated as the input
substituting in
v . k = V 0 .rho. a 2 p . 0 . ##EQU00012##
p . 1 + V 0 V 1 p . 0 - .rho. a 2 V
1 v . r = 0 [ EQ #20 ] p . 2 + .rho.
a 2 V 2 v . r = 0 [ EQ #21 ] v
r = - fA L v . r + A .rho. L p 2 - A
.rho. L p 1 [ EQ #22 ] ##EQU00013##
[0497] Cross System Transfer Function
[0498] The relationship between the speaker volume and the variable volume
may be referred to as the Cross System transfer function. This transfer
function may be derived from the above equations and is as follows:
p 2 p 0 = - V 0 V 1 .omega. n 2 s 2 + 2
.zeta..omega. n s + .alpha..omega. n 2 where [ EQ
#23 ] .omega. n 2 = a 2 A L 1 V 2 ,
.zeta. = f A 2 L .omega. n and
.alpha. = ( 1 + V 2 V 1 ) [ EQ #24 ]
##EQU00014##
[0499] Referring also to FIG. 97, a bode plot of EQ#23 is shown.
[0500] The difficulty of this relationship is that the complex poles
depend on both the variable volume, V.sub.2, and the reference volume,
V.sub.1. Any change in the mean position of the speaker may result in an
error in the estimated volume.
[0501] Cross Port Transfer Function
[0502] The relationship between the two volumes on each side of the
acoustic port may be referred to as the Cross Port transfer function.
This relationship is as follows:
p 2 p 1 = .omega. n 2 s 2 + 2 .zeta..omega. n s +
.omega. n 2 [ EQ #25 ] ##EQU00015##
[0503] which is shown graphically in FIG. 98.
[0504] This relationship has the advantage that the poles are only
dependent on the variable volume and not on the reference volume. It
does, however, have the difficulty that the resonant peak is actually due
to the inversion of the zero in the response of the reference volume
pressure. Accordingly, the pressure measurement in the reference chamber
will have a low amplitude in the vicinity of the resonance, potentially
increasing the noise in the measurement.
[0505] Cross Speaker Transfer Function
[0506] The pressures may also be measured on each side of the speaker.
This is referred to as the cross speaker transfer function:
p 1 p 0 = - V 0 V 1 s 2 + 2 .zeta..omega. n
s + .omega. n 2 s 2 + 2 .zeta..omega. n s +
.alpha..omega. n 2 [ EQ #26 ] ##EQU00016##
[0507] which is shown graphically in FIG. 99.
[0508] This transfer function has a set of complex zeros in addition to
the set of complex poles.
[0509] Looking at the limits of this transfer function: as s.fwdarw.0,
p 1 p 0 .fwdarw. - V 0 V 1 + V 2 ; ##EQU00017##
and as s.fwdarw..infin.,
p 1 p 0 .fwdarw. - V 0 V 1 . ##EQU00018##
[0510] Resonance Q Factor and Peak Response The quality of the resonance
is the ratio of the energy stored to the power loss multiplied by the
resonant frequency. For a pure second-order system, the quality factor
may be expressed as a function of the damping ratio:
Q = 1 2 .zeta. [ EQ #27 ] ##EQU00019##
[0511] The ratio of the peak response to the low-frequency response may
also be written as a function of the damping ratio:
G .omega. d = 1 .zeta. 5 - 4 .zeta. [ EQ
#28 ] ##EQU00020##
[0512] This may occur at the damped natural frequency:
.omega..sub.d=.omega..sub.n {square root over (1-.zeta.)} [EQ#29]
[0513] Volume Estimation
[0514] Volume Estimation using Cross-Port Phase
[0515] The variable volume (i.e., within volume sensor chamber 620) may
also be estimated using the cross-port phase. The transfer function for
the pressure ratio across the resonant port may be as follows:
p 2 p 1 = .omega. n 2 s 2 + bs + .omega. n 2 [
EQ #30 ] ##EQU00021##
[0516] At the 90.degree. phase point, .omega.=.omega..sub.n; where
.omega. n 2 = 1 V 2 a 2 A L ##EQU00022##
[0517] The resonant frequency may be found on the physical system using a
number of methods. A phase-lock loop may be employed to find the
90.degree. phase point--this frequency may correspond to the natural
frequency of the system. Alternatively, the resonant frequency may be
calculated using the phase at any two frequencies:
[0518] The phase, .PHI., at any given frequency will satisfy the following
relation:
tan .phi. = b .omega. .omega. 2 - .omega. n 2
where b = f A L . [ EQ #31
] ##EQU00023##
[0519] Solving for V.sub.2 results in:
V 2 = a 2 A L .omega. 2 - f .omega. cot
.phi. [ EQ #32 ] ##EQU00024##
[0520] Accordingly, the ratio of the phases at two different frequencies
.omega..sub.1 and .omega..sub.2 can be used to compute the natural
frequency of the system:
.alpha. .omega. n 2 = .omega. 1 .omega. 2 (
.omega. 1 tan .phi. 1 tan .phi. 2 - .omega.
2 ) ( .omega. 2 tan .phi. 1 tan .phi. 2
- .omega. 1 ) [ EQ #33 ] ##EQU00025##
[0521] For computational efficiency, the actual phase does not need to be
calculated. All that is needed is the ratio of the real and imaginary
parts of the response (tan .PHI.).
[0522] Re-writing EQ#33 in terms of the variable volume results in:
1 V 2 = 1 a 2 L A .omega. 1 .omega. 2 (
.omega. 1 tan .phi. 1 tan .phi. 2 - .omega.
2 ) ( .omega. 2 tan .phi. 1 tan .phi. 2
- .omega. 1 ) [ EQ #34 ] ##EQU00026##
[0523] Volume Estimation using Swept Sine
[0524] The resonant frequency of the system may be estimated using
swept-sine system identification. In this method, the response of the
system to a sinusoidal pressure variation may be found at a number of
different frequencies. This frequency response data may then used to
estimate the system transfer function using linear regression.
[0525] The transfer function for the system may be expressed as a rational
function of s. The general case is expressed below for a transfer
function with an n.sup.th order numerator and an m.sup.th order
denominator. N and D are the coefficients for the numerator and
denominator respectively. The equation has been normalized such that the
leading coefficient in the denominator is 1.
G ( s ) = N n s n + N n - 1 s n - 1 + +
N 0 s m + D m - 1 s m - 1 + D m - 2 s m - 2
+ + D 0 [ EQ #35 ] or G ( s ) =
k = 0 n N k s k s m + k = 0 m - 1 D k s
k [ EQ #36 ] ##EQU00027##
[0526] This equation may be re-written as follows:
Gs m = k = 0 n N k s k - G k = 0 m - 1
D k s k [ EQ #37 ] ##EQU00028##
[0527] Representing this summation in matrix notation resulting in the
following:
[ G 1 s 1 m G k s k m ] = [ s
1 n s 1 0 - G 1 s 1 m - 1 - G 1 s 1 0
s k n s k 0 - G k s k m
- 1 - G k s k 0 ] [ N n N 0
D m - 1 D 0 ] [ EQ #38 ] ##EQU00029##
[0528] where k is the number of data points collected in the swept sine.
To simplify the notation, this equation may be summarized using the
vectors:
y=Xc [EQ#39]
[0529] where y is k by 1, x is k by (m+n-1) and c is (m+n-1) by 1. The
coefficients may then be found using a least square approach. The error
function may be written as follows:
e=y-Xc [EQ#40]
[0530] The function to be minimized is the weighted square of the error
function; W is a k.times.k diagonal matrix.
e.sup.TWe=(y-Xc).sup.TW(y-Xc) [EQ#41]
e.sup.TWe=y.sup.TWy-(y.sup.TWXc).sup.T-y.sup.TWXc+c.sup.Tx.sup.TWXc
[EQ#42]
[0531] As the center two terms are scalars, the transpose may be
neglected.
e T We = y T Wy - 2 y T WXc + c T x T
WXc [ EQ #43 ] .differential. e T We
.differential. c = - 2 X T Wy + 2 X T WXc = 0
[ EQ #44 ] c = ( X T WX ) - 1 X T Wy
[ EQ #45 ] ##EQU00030##
[0532] It may be necessary to use the complex transpose in all of these
cases. This approach may result in complex coefficients, but the process
may be modified to ensure that all the coefficients are real. The
least-square minimization may be modified to give only real coefficients
if the error function is changed to be
e.sup.TWe=Re(y-Xc).sup.TW Re(y-Xc)+Im(y-Xc).sup.TW Im(y-Xc) [EQ#46]
[0533] Accordingly, the coefficients may be found with the relation:
c=(Re(X).sup.TWRe(X)+Im(X).sup.TWIm(X)).sup.-1(Re(X).sup.TWRe(y)+Im(X).s-
up.TWIm(y)) [EQ#47]
[0534] Solution for a 2nd Order System
[0535] For a system with a 0.sup.th order numerator and a second order
denominator as shown in the transfer function:
G ( s ) = N 0 s 2 + D 1 s + D 0 [ EQ
#48 ] ##EQU00031##
[0536] The coefficients in this transfer function may be found based on
the expression found in the previous section:
c = ( Re ( X ) T W Re ( X ) + Im (
X ) T W Im ( X ) ) - 1 ( Re ( X ) T
W Re ( y ) + Im ( X ) T W Im ( y )
) [ EQ #49 ] where :
y = [ G 1 s 1 2 G k s k 2 ] , X =
[ 1 - G 1 s 1 - G 1 1 - G k
s k - G k ] , and c = [ N 0 D 1
D 0 ] [ EQ #50 ) ##EQU00032##
[0537] To simplify the algorithm, we may combine some of terms:
c=D.sup.-1b [EQ#51]
[0538] where:
D=Re(X).sup.TRe(X)+Im(X).sup.TWIm(X) [EQ#52]
b=Re(X).sup.TW Re(y)+Im(X).sup.TW Im(y) [EQ#53]
[0539] To find an expression for D in terms of the complex response vector
G and the natural frequency s=j.omega., X may be split into its real and
imaginary parts:
Re ( X ) = [ 1 .omega. k Im ( G 1 ) -
Re ( G 1 ) 1 .omega. k Im ( G k )
- Re ( G k ) ] , [ EQ #54 ] Im ( X
) = [ 0 - .omega. k Re ( G 1 ) - Im ( G 1
) 0 - .omega. k Re ( G k ) - Im
( G k ) ] ##EQU00033##
[0540] The real and imaginary portions of the expression for D above may
then become:
[ EQ #55 ] ##EQU00034## Re ( X ) T W
Re ( X ) = [ i = 1 k w i i = 1 k
w i Im ( G i ) .omega. i - i = 1 k w i
Re ( G i ) i = 1 k w i Im ( G i )
.omega. i i = 1 k w i Im ( G i ) 2 .omega.
i 2 - i = 1 k w i Im ( G i ) Re ( G i
) .omega. i - i = 1 k w i Re ( G i )
- i = 1 k w i Im ( G i ) Re ( G i )
.omega. i i = 1 k w i Re ( G i ) 2 ]
[ EQ #56 ] Im ( X ) T W Im
( X ) = [ 0 0 0 0 i = 1 k w i Re
( G i ) 2 .omega. i 2 i = 1 k w i Im ( G i
) Re ( G i ) .omega. i 0 i = 1 k w i
Im ( G i ) Re ( G i ) .omega. i i = 1 k
w i Im ( G i ) 2 ] ##EQU00034.2##
[0541] Combining these terms results in the final expression for the D
matrix, which may contain only real values.
[ EQ #57 ] ##EQU00035## D = [ i = 1 k
w i i = 1 k w i Im ( G i ) .omega. i -
i = 1 k w i Re ( G i ) i = 1 k w i
Im ( G i ) .omega. i i = 1 k w i ( Re
( G i ) 2 + Im ( G i ) 2 ) .omega. i 2 0
- i = 1 k w i Re ( G i ) 0 i = 1 k
w i ( Re ( G i ) 2 + Im ( G i ) 2 ) ]
##EQU00035.2##
[0542] The same approach may be taken to find an expression for the b
vector in terms of G and .omega.. The real and imaginary parts of y are
as follows:
Re ( y ) = [ - Re ( G 1 ) .omega. 1 2
- Re ( G k ) .omega. k 2 ] , Im ( y )
= [ - Im ( G 1 ) .omega. 1 2 - Im (
G k ) .omega. k 2 ] [ EQ #58 ] ##EQU00036##
[0543] Combining the real and imaginary parts results in the expression
for the b vector as follows:
b = Re ( X ) T W Re ( y ) + Im ( X )
T W Im ( y ) = [ - i = 1 k w i
Re ( G i ) .omega. i 2 0 i = 1 k w i
( Re ( G i ) 2 + Im ( G i ) 2 ) .omega. i 2
] [ EQ #59 ] ##EQU00037##
[0544] The next step is to invert the D matrix. The matrix is symmetric
and positive-definite so the number of computations needed to find the
inverse will be reduced from the general 3.times.3 case. The general
expression for a matrix inverse is:
D - 1 = 1 det ( D ) adj ( D ) [ EQ
#60 ] ##EQU00038##
[0545] If D is expressed as follows:
D = [ d 11 d 12 d 13 d 12 d 22 0 d 13
0 d 33 ] [ EQ #61 ] ##EQU00039##
[0546] then the adjugate matrix may be written as follows:
adj ( D ) = [ d 22 0 0 d 33 -
d 12 0 d 13 d 33 d 12 d 22 d 13
0 - d 12 d 13 0 d 33 d 11
d 13 d 13 d 33 - d 11 d 12 d 13 0
d 12 d 13 d 22 0 - d 11 d
13 d 12 0 d 11 d 12 d 12 d 22
] = [ a 11 a 12 a 13 a 12 a 22 a 23
a 13 a 32 a 33 ] [ EQ #62 ] ##EQU00040##
[0547] Due to symmetry, only the upper diagonal matrix may need to be
calculated.
[0548] The Determinant may then be computed in terms of the adjugate
matrix values, taking advantage of the zero elements in the original
array:
det(D)=a.sub.12d.sub.12+a.sub.22d.sub.22 [EQ#63]
[0549] Finally, the inverse of D may be written as follows:
D - 1 = 1 det ( D ) adj ( D ) [ EQ
#64 ] ##EQU00041##
[0550] Since we are trying to solve:
c = D - 1 b = 1 det ( D ) adj ( D )
b then : [ EQ #65 ] c = 1
det ( D ) [ a 11 a 12 a 13 a 12 a 22 a
23 a 13 a 32 a 33 ] [ b 1 0 b 3
] = 1 det ( D ) [ a 11 b 1 + a 13 b 3
a 12 b 1 + a 23 b 3 a 13 b 1 + a 33
b 3 ] [ EQ #66 ] ##EQU00042##
[0551] The final step is to get a quantitative assessment of how well the
data fits the model. Accordingly, the original expression for the error
is as follows:
e.sup.TWe=Re(y-Xc).sup.TW Re(y-Xc)+Im(y-Xc).sup.TW Im(y-Xc) [EQ#67]
[0552] This may be expressed in terms of the D matrix and the b and c
vectors as follows:
e T We = h - 2 c T b + c T Dc where
: [ EQ #68 ] h = Re ( y T ) W
Re ( y ) + Im ( y T ) W Im ( y ) [
EQ #69 ] h = i = 1 k w i ( Re ( G i
) 2 + Im ( G i ) 2 ) .omega. i 4 [ EQ
#70 ] ##EQU00043##
[0553] The model fit error may also be used to detect sensor failures.
[0554] Alternate Solution for a 2nd Order System
G ( s ) = N n s n + N n - 1 s n - 1 + +
N 0 s m + D m - 1 s m - 1 + D m - 2 s m - 2
+ + D 0 or [ EQ #71 ] G ( s ) =
k = 0 n N k s k s m + k = 0 m - 1 D k s
k [ EQ #72 ] ##EQU00044##
[0555] This equation may be re-written as follows:
G = k = 0 n N k s k - m - G k = 0 m - 1
D k s k - m [ EQ #73 ] ##EQU00045##
[0556] Putting this summation into matrix notation results in the
following:
[ G 1 G k ] = [ s 1 n - m s 1 -
m - G 1 s 1 - 1 - G 1 s 1 - m
s k n - m s k - m - G k s k - 1
- G k s k - m ] [ N n N 0
D m - 1 D 0 ] [ EQ #74 ] ##EQU00046##
[0557] For a system with a 0.sup.th order numerator and a second order
denominator as shown in the transfer function:
G ( s ) = N 0 s 2 + D 1 s + D 0 [ EQ
#75 ] ##EQU00047##
[0558] The coefficients in this transfer function may be found based on
the expression found in the previous section:
c = ( Re ( X ) T W Re ( X ) + Im (
X ) T W Im ( X ) ) - 1 ( Re ( X ) T
W Re ( y ) + Im ( X ) T W Im ( y )
) [ EQ #76 ] where y = [ G 1
G k ] , X = [ s 1 - 2 - G 1 s 1 - 1
- G 1 s 1 - 2 s k - 2 - G k
s k - 1 - G k s k - 2 ] , and c = [
N 0 D 1 D 0 ] [ EQ #77 ] ##EQU00048##
[0559] To simplify the algorithm, some terms may be combined:
c=D.sup.-1b[ [EQ#78]
[0560] where:
D=Re(X).sup.TW Re(X)+Im(X).sup.TIm(X) [EQ#79]
b=Re(X).sup.TW Re(y)+Im(X).sup.TW Im(y) [EQ#80]
[0561] To find an expression for D in terms of the complex response vector
G and the natural frequency s=j.omega., split X may be split into its
real and imaginary parts:
Re ( X ) = [ - .omega. 1 - 2 - .omega. 1 - 1
Im ( G 1 ) .omega. 1 - 2 Re ( G 1 )
- .omega. k - 2 - .omega. k - 1 Im ( G k )
.omega. k - 2 Re ( G k ) ] [ EQ #81 ]
Im ( X ) = [ 0 - .omega. 1 - 1 Re ( G 1
) .omega. 1 - 2 Im ( G 1 ) 0 -
.omega. k - 1 Re ( G k ) .omega. k - 2 Im (
G k ) ] [ EQ #82 ] ##EQU00049##
[0562] The real and imaginary portions of the expression for D above may
then become:
Re ( X ) T W Re ( X ) = [ i = 1 k
w i .omega. i - 4 i = 1 k w i Im ( G i )
.omega. i - 3 - i = 1 k w i Re ( G i )
.omega. i - 4 i = 1 k w i Im ( G i )
.omega. i - 3 i = 1 k w i Im ( G i ) 2
.omega. i - 2 - i = 1 k w i Im ( G i ) Re
( G i ) .omega. i - 3 - i = 1 k w i Re
( G i ) .omega. i - 4 - i = 1 k w i Im
( g i ) Re ( G i ) .omega. i - 3 i = 1 k
w i Re ( G i ) 2 .omega. i - 4 ] [ EQ
#83 ] Im ( X ) T W Im ( X ) = [ 0
0 0 0 i = 1 k w i Re ( G i ) 2
.omega. i - 2 - i = 1 k w i Im ( G i ) Re
( G i ) .omega. i - 3 0 - i = 1 k w i
Im ( G i ) Re ( G i ) .omega. i - 2 i =
1 k w i Im ( G i ) 2 .omega. i - 4 ] [
EQ #84 ] ##EQU00050##
[0563] Combining these terms results in the final expression for the D
matrix, which may contain only real values.
D = [ i = 1 k w i .omega. i - 4 i = 1 k
w i Im ( G i ) .omega. i - 3 - i = 1 k
w i Re ( G i ) .omega. i - 4 i = 1 k
w i Im ( G i ) .omega. i - 3 i = 1 k w i
( Re ( G i ) 2 + Im ( G i ) 2 ) .omega. i
- 2 - 2 i = 1 k w i Im ( G i ) Re (
G i ) .omega. i - 3 - i = 1 k w i Re (
G i ) .omega. i - 4 - 2 i = 1 k w i Im
( G i ) Re ( G i ) .omega. i - 3 i = 1 k
w i ( Re ( G i ) 2 + Im ( G i ) 2 )
.omega. i - 4 ] [ EQ #85 ] ##EQU00051##
[0564] The same approach may be taken to find an expression for the b
vector in terms of G and .omega.. The real and imaginary parts of y areas
follows:
Re ( y ) = [ - Re ( G 1 ) - Re (
G k ) ] , Im ( y ) = [ - Im ( G 1 )
- Im ( G k ) ] [ EQ #86 ] ##EQU00052##
[0565] Combining the real and imaginary parts results in the expression
for the b vector as follows:
b = Re ( X ) T W Re ( y ) + Im ( X )
T W Im ( y ) = [ - i = 1 k w i
Re ( G i ) .omega. i - 2 - i = 1 k w i (
Im ( G i ) + Re ( G i ) .omega. i - 1
i = 1 k w i ( Re ( G i ) 2 + Im ( G i ) 2
) .omega. i - 2 ] [ EQ #87 ]
##EQU00053##
Implementing Acoustic Volume Sensing
[0566] Collecting the Frequency Response Data and Computing the Complex
Response
[0567] To implement volume sensor assembly 148, volume sensor assembly 148
should determine the relative response of reference microphone 626 and
invariable volume microphone 630 to the acoustic wave set up by speaker
assembly 622. This may be accomplished by driving speaker assembly 622
with a sinusoidal output at a known frequency; the complex response of
microphones 626, 630 may then be found at that driving frequency.
Finally, the relative response of microphones 626, 630 may be found and
corrected for alternating sampling by e.g., an analog-to-digital
convertor (i.e., ADC).
[0568] Additionally, the total signal variance may be computed and
compared to the variance of pure tone extracted using the discrete
Fourier transform (i.e., DFT). This may result in a measure of how much
of the signal power comes from noise sources or distortion. This value
may then be used to reject and repeat bad measurements.
[0569] Computing the Discrete Fourier Transform
[0570] The signal from the microphone may be sampled synchronously with
the output to speaker assembly 622 such that a fixed number of points, N,
are taken per wavelength. The measured signal at each point in the
wavelength may be summed over an integer number of wavelengths, M, and
stored in an array x by the ISR for processing after all the data for
that frequency has been collected.
[0571] A DFT may be performed on the data at the integer value
corresponding to the driven frequency of the speaker. The general
expression for the first harmonic of a DFT is as follows:
x k = 2 MN n = 0 N - 1 x n e - 2 .pi.
i N kn [ EQ #88 ] ##EQU00054##
[0572] The product MN may be the total number of points and the factor of
two may be added such that the resulting real and imaginary portions of
the answer match the amplitude of the sine wave:
x n = re ( x k ) cos ( 2 .pi. N kn )
+ im ( x k ) sin ( 2 .pi. N kn ) [ EQ #89
] ##EQU00055##
[0573] This real part of this expression may be as follows:
re ( x ) = 1 MN n = 0 N - 1 x n cos ( 2
.pi. N n ) [ EQ #90 ] ##EQU00056##
[0574] We may take advantage of the symmetry of the cosine function to
reduce the number of computations needed to compute the DFT. The
expression above may be equivalent to:
re ( x ) = 1 MN [ ( x 0 - x 1 2 N ) +
n = 1 1 4 N - 1 sin ( .pi. 2 - 2 .pi. N n )
[ ( x n - x 1 2 N + n ) - ( x 1 2 N + n
- x N - n ) ] ] [ EQ #91 ] ##EQU00057##
[0575] Similarly, for the imaginary portion of the equation:
im ( x ) = - 2 MN n = 0 N - 1 x n sin (
2 .pi. N n ) [ EQ #92 ] ##EQU00058##
[0576] which may be expressed as follows:
im ( x ) = - 2 MN [ ( x 1 4 N - x 3 4
N ) + n = 1 1 4 N - 1 sin ( 2 .pi. N n )
[ ( x n - x 1 2 N + n ) - ( x 1 2 N + n
- x N - n ) ] ] [ EQ #93 ] ##EQU00059##
[0577] The variance of this signal may be calculated as follows:
.sigma..sup.2=1/2(re(x).sup.2+im(x).sup.2) [EQ#94]
[0578] The maximum possible value of the real and imaginary portions of x
may be 2.sup.11; which corresponds to half the AD range. The maximum
value of the tone variance may be 2.sup.21; half the square of the AD
range.
[0579] Computing the Signal Variance
[0580] The pseudo-variance of the signal may be calculated using the
following relation:
.sigma. 2 = 1 NM 2 n = 0 N - 1 x n 2 - 1
N 2 M 2 ( n = 0 N - 1 x n ) 2 [ EQ #95
] ##EQU00060##
[0581] The result may be in the units of AD counts squared. It may only be
the "pseudo-variance" because the signal has been averaged over M periods
before the variance is calculated over the N samples in the "averaged"
period. This may be a useful metric, however, for finding if the
"averaged" signal looks like a sinusoid at the expected frequency. This
may be done by comparing the total signal variance to that of the
sinusoid found in the discrete Fourier transform.
[0582] The summation may be on the order of
n = 0 N - 1 x n 2 = O ( NM 2 2 24 )
##EQU00061##
for a 12-bit ADC. If N<2'=128 and M<2.sup.6=64, then the summation
will be less than 2.sup.43 and may be stored in a 64-bit integer. The
maximum possible value of the variance may result if the ADC oscillated
between a value of 0 and 2.sup.12 on each consecutive sample. This may
result in a peak variance of 1/4(2.sup.12).sup.2=2.sup.22 so the result
may be stored at a maximum of a 1/2.sup.9 resolution in a signed 32-bit
integer.
[0583] Computing the Relative Microphone Response
[0584] The relative response (G) of microphones 626, 630 may be computed
from the complex response of the individual microphones:
G = x va r x ref = x va r x ref x
ref * x ref * [ EQ #96 ] Re ( G ) = Re (
x v ar ) Re ( x ref ) + Im ( x
va r ) Im ( x ref ) Re ( x ref ) 2 +
Im ( x ref ) 2 [ EQ #97 ] Im ( g ) =
Re ( x ref ) Im ( x va r ) - Re (
x va r ) Im ( x ref ) Re ( x ref )
2 + Im ( x ref ) 2 [ EQ #98 ] ##EQU00062##
[0585] The denominator of either expression may be expressed in terms of
the reference tone variance computed in the previous section as follows:
Re(x.sub.ref).sup.2+Im(x.sub.ref).sup.2=2.sigma..sub.ref.sup.2 [EQ#99]
[0586] Correcting for A/D Skew
[0587] The signals from microphones 626, 630 may not be sampled
simultaneously; the A/D ISR alternates between microphones 626, 630,
taking a total of N samples per wavelength for each of microphones 626,
630. The result may be a phase offset between two microphones 626, 630 of
.pi. N . ##EQU00063##
To correct for this phase offset, a complex rotation may be applied to
the relative frequency response computed in the previous section:
G rotated = G ( cos ( .pi. N ) + i sin (
.pi. N ) ) [ EQ #100 ] ##EQU00064##
[0588] Reference Models
[0589] Second and Higher Order Models
[0590] Leakage through the seals (e.g., seal assembly 1404) of volume
sensor chamber 620 may be modeled as a second resonant port (e.g., port
1504, FIG. 100) connected to an external volume (e.g., external volume
1506, FIG. 100).
[0591] The system of equations describing the three-chamber configuration
may be as follows:
p 1 + .rho. a 2 V 1 ( v k - v r
12 ) = 0 [ EQ #101 ] p 2 + .rho.
a 2 V 2 ( v r 12 - v r 23 ) = 0
[ EQ #102 ] v r 12 = - f 12 A 12
L 12 v r 12 + A 12 .rho. L 12 (
p 2 - p 1 ) [ EQ #103 ] p 3 + .rho.
a 2 V 3 v r 23 = 0 [ EQ #104 ]
v r 23 = - f 23 A 23 L 23 v r
23 + A 23 .rho. L 23 ( p 3 - p 2 )
[ EQ #105 ] ##EQU00065##
[0592] Putting these equations into state-space results in the following:
[ p 1 p 2 p 3 v 12 v
23 ] = [ 0 0 0 .rho. a 2 V 1 0 0
0 0 - .rho. a 2 V 2 .rho. a 2 V 2
0 0 0 0 - .rho. a 2 V 3 - A 12 .rho.
L 12 A 12 .rho. L 12 0 - b 12 0
0 - A 23 .rho. L 23 A 23 .rho. L 23
0 - b 23 ] [ p 1 p 2 p 3 v 12
v 23 ] + [ - .rho. a 2 V 1 0 0 0
0 ] [ v k ] [ EQ #106 ] ##EQU00066##
[0593] the frequency response of which may be represented graphically in
the Bode diagram shown in FIG. 101 and which may also be written in
transfer function form:
p 2 p 1 = .omega. 12 2 ( s 2 + b 23 s +
.omega. 23 2 ) ( s 2 + b 12 s + .omega. 12 2 )
( s 2 + b 23 s + .omega. 23 2 ) + V 3 V 2
.omega. 23 2 ( s + b 12 ) s [ EQ #107 ]
##EQU00067##
[0594] Expanding the denominator results in the following:
p 2 p 1 = .omega. 12 2 ( s 2 + b 23 s +
.omega. 23 2 ) s 4 + ( b 12 + b 23 ) s 3 +
( b 12 b 23 + .omega. 12 2 + .omega. 23 2 ( 1 + V 3
V 2 ) ) s 2 + ( b 23 .omega. 12 2 + b 12
.omega. 23 2 ( 1 + V 3 V 2 ) ) s + .omega.
12 2 .omega. 23 2 [ EQ #108 ] ##EQU00068##
[0595] A bubble underneath the diaphragm material in the variable volume
will follow the same dynamic equations as a leakage path. In this case,
the diaphragm material may act as the resonant mass rather than the
leakage port. Accordingly, the equation may be as follows:
m{umlaut over (x)}=.DELTA.pA-b.sub.m{dot over (x)} [EQ#109]
[0596] wherein m is the mass of the diaphragm, A is the cross sectional
area of the diaphragm that can resonate, and b.sub.m is the mechanical
damping. EQ#106 may be written in terms of the volume flow rate:
v = - b m v + .DELTA. p A 2 m
[ EQ #110 ] ##EQU00069##
[0597] wherein the volume of the air bubble is V.sub.3. If the bubble
volume is substantially smaller than the acoustic volume
V.sub.3<<V.sub.2 than the transfer function may be simplified to:
p 2 p 1 = .omega. 12 2 ( s 2 + b 23 s +
.omega. 23 2 ) ( s 2 + b 12 s + .omega. 12 2 ) (
s 2 + b 23 s + .omega. 23 2 ( 1 + V 3 V 2 ) )
[ EQ #111 ] ##EQU00070##
[0598] Second Order with Time Delay
[0599] The volume sensor assembly 148 equations derived above assume that
the pressure is the same everywhere in the acoustic volume. This is only
an approximation, as there are time delays associated with the
propagation of the sound waves through the volume. This situation may
look like a time delay or a time advance based on the relative position
of the microphone and speakers.
[0600] A time delay may be expressed in the Laplace domain as:
G(s)=e.sup.-.DELTA.Ts [EQ#112]
[0601] which makes for a non-linear set of equations. However, a
first-order Pade approximation of the time delay may be used as follows:
G ( s ) = - s + 2 .DELTA. T s - 2 .DELTA.
T [ EQ #113 ] ##EQU00071##
[0602] which is shown graphically in FIG. 102.
[0603] Three Chamber Volume Estimation Volume sensor assembly 148 may also
be configured using a third reference volume (e.g., reference volume
1508; FIG. 103) connected with a separate resonant port (e.g., port 1510;
FIG. 103). This configuration may allow for temperature-independent
volume estimation.
[0604] The system of equations describing the three-chamber configuration
are as follows:
p 1 + .rho. a 2 V 1 ( v k - v r
12 - v r 13 ) = 0 [ EQ #114 ] p
2 + .rho. a 2 V 2 v r 12 = 0 [
EQ #115 ] v r 12 = - f 12 A 12 L
12 v r 12 + A 12 .rho. L 12 ( p
2 - p 1 ) [ EQ #116 ] p 3 + .rho. a
2 V 3 v r 13 = 0 [ EQ #117 ] v
r 13 = - f 13 A 13 L 13 v r 13
+ A 13 .rho. L 13 ( p 2 - p 1 ) [ EQ
#118 ] ##EQU00072##
[0605] Using these equations and solving for the transfer function across
each of the resonant ports results in the following:
p 2 p 1 = .omega. n 12 2 s 2 + 2 .zeta. 12
.omega. n 12 s + .omega. n 12 2
where [ EQ #119 ] .omega. n 12 = 1 V 2
a 2 A 12 L 12 and .zeta. = f 12 A 12 2
L 12 .omega. n 12 [ EQ #120 ] p 3
p 1 = .omega. n 13 2 s 2 + 2 .zeta. 13 .omega.
n 13 s + .omega. n 13 2 where [ EQ
#121 ] .omega. n 13 = 1 V 3 a 2 A 13
L 13 and .zeta. = f 13 A 13 2 L 13
.omega. n 13 [ EQ #122 ] ##EQU00073##
[0606] The volume of volume sensor chamber 620 may be estimated using the
ratio of the natural frequency of the two resonant ports as follows:
.omega. n 13 2 .omega. n 12 2 = V 2 V 3
A 13 A 12 L 12 L 13 [ EQ #123 ] ##EQU00074##
[0607] EQ#120 illustrates that the volume of volume sensor chamber 620 may
be proportional to reference volume 1508. The ratio of these two volumes
(in the ideal model) may only depend on the geometry of the resonant port
(e.g., port 1510; FIG. 103) and has no dependence upon temperature.
[0608] Exponential Volume Model
[0609] Assume the flow out through the flow resistance has the following
form:
V out = V avs .tau. [ EQ #124 ] ##EQU00075##
[0610] Assuming a fixed input flow rate from the pump chamber, the volume
of volume sensor chamber 620 is based upon the following differential
equation:
V avs = V i n - V out = V i
n - V avs .tau. [ EQ #125 ] ##EQU00076##
[0611] which gives the following solution assuming a zero initial volume:
V avs = V i n .tau. ( 1 - e - t .tau. )
[ EQ #126 ] ##EQU00077##
[0612] Accordingly, the output flow rate flows:
V out = V i n ( 1 - e - t .tau. ) [
EQ #127 ] ##EQU00078##
[0613] The volume delivered during the pump phase may be written:
V out = V i n [ t - .tau. ( 1 - e - t .tau.
) ] [ EQ #128 ] ##EQU00079##
[0614] Device Calibration
[0615] The model fit allows the resonant frequency of the port to be
extracted from the sine sweep data. The next step is to relate this value
to the delivered volume. The ideal relationship between the resonant
frequency and the delivered volume to be expressed as follows:
.omega. n 2 = a 2 A L 1 V 2 [ EQ #129 ]
##EQU00080##
[0616] The speed of sound will vary with temperature, so it may be useful
to split out the temperature effects.
.omega. n 2 = .gamma. RA L T V 2 [ EQ
#130 ] ##EQU00081##
[0617] The volume may then be expressed as a function of the measured
resonant frequency and the temperature:
V 2 = C T .omega. n 2 [ EQ #131 ]
##EQU00082##
[0618] Where c is the calibration constant
C = .gamma. RA L ##EQU00083##
[0619] Implementation Details
[0620] End Effects
[0621] The air resonating in the port (e.g., port assembly 624) may extend
out into the acoustic volumes at the end of each oscillation. The
distance the air extends may be estimated based on the fundamental volume
sensor assembly equations. For any given acoustic volume, the distance
the air extends into the volume may be expressed as a function of the
pressure and port cross-sectional area:
x = V .rho. a 2 A p [ EQ #132 ]
##EQU00084##
[0622] If we assume the following values:
V = 28.8 .times. 10 - 6 L [ EQ #133 ]
.rho. = 1.292 kg m 3 [ EQ #134 ] a = 340
m s [ EQ #135 ] d = 0.5 mm [ EQ
#136 ] p = 1 Pa ( Approximately 100
dB ) [ EQ #137 ] ##EQU00085##
[0623] Accordingly, the air will extend roughly 1.9 mm in to the acoustic
chamber.
[0624] Sizing V1 (i.e., the fixed volume) relative to V2 (i.e., the
variable volume)
[0625] Sizing V.sub.1 (e.g., fixed volume 1500) may require trading off
acoustic volume with the relative position of the poles and zeros in the
transfer function. The transfer function for both V.sub.1 and V.sub.2
(e.g., variable volume 1502) are shown below relative to the volume
displacement of speaker assembly 622.
p 2 v k = .rho. a 2 V 1 .omega. n 2 s 2
+ 2 .zeta. .omega. n s + .alpha. .omega. n 2
[ EQ #138 ] p 1 v k = - .rho. a
2 V 1 s 2 + 2 .zeta. .omega. n s +
.alpha. .omega. n 2 s 2 + 2 .zeta. .omega.
n s + .omega. n 2 [ EQ #139 ] where
.omega. n 2 = a 2 A L 1 V 2 , .zeta. = fA 2
L .omega. n and .alpha. = ( 1 + V 2
V 1 ) [ EQ # 140 ] ##EQU00086##
[0626] As V.sub.1 is increased the gain may decrease and the speaker may
be driven at a higher amplitude to get the same sound pressure level.
However, increasing V.sub.1 may also have the benefit of moving the
complex zeros in the p.sub.1 transfer function toward the complex poles.
In the limiting case where V.sub.1.fwdarw..infin., .alpha..fwdarw.1 and
you have pole-zero cancellation and a flat response. Increasing V.sub.1,
therefore, may have the benefit of reducing both the resonance and the
notch in the p.sub.1 transfer function, and moving the p.sub.2 poles
toward .omega..sub.n; resulting in a lower sensitivity to measurement
error when calculating the p.sub.2/p.sub.1 transfer function.
[0627] FIG. 104 is a graphical representation of:
p 1 v k [ EQ #141 ] ##EQU00087##
[0628] FIG. 105 is a graphical representation of
p 2 v k [ EQ #142 ] ##EQU00088##
[0629] Aliasing Higher frequencies may alias down to the frequency of
interest, wherein the aliased frequency may be expressed as follows:
f=|f.sub.n-nf.sub.s| [EQ#143]
[0630] where f.sub.s is the sampling frequency, f.sub.n is the frequency
of the noise source, n is a positive integer, and f is the aliased
frequency of the noise source.
[0631] The demodulation routine may effectively filter out noise except at
the specific frequency of the demodulation. If the sample frequency is
set dynamically to be a fixed multiple of the demodulation frequency,
then the frequency of the noise that can alias down to the demodulation
frequency may be a fixed set of harmonics of that fundamental frequency.
[0632] For example, if the sampling frequency is eight times the
demodulation frequency, then the noise frequencies that can alias down to
that frequency are as follows:
f n f = { 1 n .beta. + 1 , 1 n .beta.
- 1 } = { 1 7 , 1 9 , 1 15 , 1 17 , 1 23 , 1 25 ,
} [ EQ #144 ] where .beta. = f s
f = 8. For .beta. = 16 , the
following series would result :
f n f = { 1 15 , 1 17 , 1 31 , 1 33 , } [
EQ #145 ] ##EQU00089##
[0633] Performance
[0634] Sensitivity to Temperature
[0635] The sensitivity to temperature may be split into a gain change and
a noise change. If the temperature is off by a factor of dT, the
resulting gain error may be:
V 2 = c ( T 2 .omega. 2 2 - T 1 .omega. 1 2 )
[ EQ #147 ] ##EQU00090##
[0636] Accordingly, if the same temperature is used for both sine sweeps,
any error in the temperature measurement may look like a gain change to
the system.
e gain = 1 - T measured T actual [ EQ #148 ]
##EQU00091##
[0637] Therefore, for a 1.degree. K temperature error, the resulting
volume error may be 0.3% at 298.degree. K. This error may include both
the error in the temperature sensor and the difference between the sensor
temperature and the temperature of the air within volume sensor assembly
148.
[0638] The measurement, however, may be more susceptible to noise in the
temperature measurement. A temperature change during the differential
sine sweeps may result in an error that looks more like an offset rather
than a gain change:
V error = c .omega. 2 .DELTA. T [ EQ
#149 ] ##EQU00092##
[0639] Accordingly, if the measurement varies by 0.1 K during the two
measurement sine sweeps, the difference may be 0.012 uL. Therefore, it
may be better to use a consistent temperature estimate for each delivery
rather than taking a separate temperature measurement for each sine sweep
(as shown in FIG. 107).
[0640] The LM73 temperature sensor has a published accuracy of
+/-1.degree. C. and a resolution of 0.03 C. Further, the LM73 temperature
sensor seems to consistently have a startup transient of about
0.3.degree. C. that takes about five sine sweeps to level out (as shown
in FIG. 108).
[0641] Since the above-described infusion pump assemblies (e.g., infusion
pump assembly 100, 100', 400, 500) provides discrete deliveries of
infusible fluid, the above-described infusion pump assemblies may be
modeled entirely in the discrete domain (in the manner shown in FIG.
109), which may be reduced to the following:
G p ( z ) = Kz z - 1 [ EQ #150 ]
##EQU00093##
[0642] A discrete-time PI regulator may perform according to the
following:
G c ( z ) = K p ( 1 + T s T I z z - 1 )
[ EQ #151 ] ##EQU00094##
[0643] The AVS system described above works by comparing the acoustic
response in fixed volume 1500 and variable volume 1502 to a speaker
driven input and extracting the volume of the variable volume 1502. As
such, there is a microphone in contact with each of these separate
volumes (e.g., microphones 626, 630). The response of variable volume
microphone 630 may also be used in a more gross manner to detect the
presence or absence of disposable housing assembly 114. Specifically, if
disposable housing assembly 114 is not attached to (i.e., positioned
proximate) variable volume 1502, essentially no acoustic response to the
speaker driven input should be sensed. The response of fixed volume 1500,
however, should remain tied to the speaker input. Thus, the microphone
data may be used to determine whether disposable housing assembly 114 by
simply ensuring that both microphones exhibit an acoustic response. In
the event that microphone 626 (i.e., the microphone positioned proximate
fixed volume 1500) exhibits an acoustic response and microphone 630
(i.e., the microphone positioned proximate variable volume 1502) does not
exhibit an acoustic response, it may be reasonably concluded that
disposable housing assembly 114 is not attached to reusable housing
assembly 102. It should be noted that a failure of variable volume
microphone 630 may also appear to be indicative of disposable housing
assembly 114 not being attached, as the failure of variable volume
microphone 630 may result in a mid-range reading that is nearly
indistinguishable from the microphone response expected when disposable
housing assembly 114 is not attached.
[0644] For the following discussion, the following nomenclature may be
used:
TABLE-US-00010
Symbols
.alpha..sub.max (f) maximum read at a given frequency
.alpha..sub.min (f) minimum read at a given frequency
.delta. difference between max and min sums
f individual frequency
F set of sine sweep frequencies
N number of frequencies in each sine sweep, F
.PHI. boolean disposable attached flag
.sigma.max sum of maximum ADC reads
.sigma.min sum of minimum ADC reads
T max/min ADC difference threshold
Subscripts
i sweep number
ref reference volume
var variable volume
[0645] As part of the demodulation routine employed in each frequency
response calculation, the minimum and maximum readings of both fixed
volume microphone 626 and variable volume microphone 630 may be
calculated. The sum of these maximum and minimum values may be calculated
over the entire sine-sweep (as discussed above) for both microphone 626
and microphone 630 as follows.
.sigma. max = f .di-elect cons. F .alpha. max
( f ) [ EQ #152 ] .sigma. min = f
.di-elect cons. F .alpha. min ( f ) [ EQ #153 ]
##EQU00095##
[0646] and the difference between these two summations may be simplified
as follows:
.delta.=.sigma.max-.sigma.min [EQ#154]
[0647] While .delta. may be divided by the number of sine sweeps to get
the average minimum/maximum difference for the sine sweep (which is then
compared to a threshold), the threshold may equivalently be multiplied by
N for computational efficiency. Accordingly, the basic disposable
detection algorithm may be defined as follows:
.phi. i = { 1 if .delta. var > N * T 0
if .delta. var < N * T & .delta. ref
> N * T [ EQ #155 ] ##EQU00096##
[0648] The additional condition that the maximum/minimum difference be
greater than the threshold is a check performed to ensure that a failed
speaker is not the cause of the acoustic response received. This
algorithm may be repeated for any sine-sweep, thus allowing a detachment
of disposable housing assembly 114 to be sensed within e.g., at most two
consecutive sweeps (i.e., in the worst case scenario in which disposable
housing assembly 114 is removed during the second half of an in-progress
sine sweep).
[0649] Thresholding for the above-described algorithm may be based
entirely on numerical evidence. For example, examination of typical
minimum/maximum response differences may show that no individual
difference is ever less than five hundred ADC counts. Accordingly, all
data examined while disposable housing assembly 114 is detached from
reusable housing assembly 102 may show that all minimum/maximum response
differences as being well under five hundred ADC counts. Thus, the
threshold for .delta. may be set at T=500.
[0650] While volume sensor assembly 148 is described above as being
utilized within an infusion pump assembly (e.g., infusion pump assembly
100), this is for illustrative purposes only and is not intended to be a
limitation of this disclosure, as other configurations are possible and
are considered to be within the scope of this disclosure. For example,
volume sensor assembly 148 may be used within a process control
environment for e.g., controlling the quantity of chemicals mixed
together. Alternatively, volume sensor assembly 148 may be used within a
beverage dispensing system to control e.g., the quantity of ingredients
mixed together.
[0651] While volume sensor assembly 148 is described above as utilizing a
port (e.g., port assembly 624) as a resonator, this is for illustrative
purposes only, as other configurations are possible and are considered to
be within the scope of this disclosure. For example, a solid mass (not
shown) may be suspended within port assembly 624 and may function as a
resonator for volume sensor assembly 148. Specifically, the mass (not
shown) for the resonator may be suspended on a diaphragm (not shown)
spanning port assembly 624. Alternatively, the diaphragm itself (not
shown) may act as the mass for the resonator. The natural frequency of
volume sensor assembly 148 may be a function of the volume of variable
volume 1502. Accordingly, if the natural frequency of volume sensor
assembly 148 can be measured, the volume of variable volume 1502 may be
calculated.
[0652] The natural frequency of volume sensor assembly 148 may be measured
in a number of different ways. For example, a time-varying force may be
applied to the diaphragm (not shown) and the relationship between that
force and the motion of the diaphragm (not shown) may be used to estimate
the natural frequency of volume sensor assembly 148. Alternately the mass
(not shown) may be perturbed and then allowed to oscillate. The unforced
motion of the mass (not shown) may then be used to calculate the natural
frequency of volume sensor assembly 148.
[0653] The force applied to the resonant mass (not shown) may be
accomplished in various ways, examples of which may include but are not
limited to: [0654] speaker assembly 622 may create a time-varying
pressure within fixed volume 1500; [0655] the resonant mass (not shown)
may be a piezoelectric material responding to a time-varying
voltage/current; and [0656] the resonant mass (not shown) may be a voice
coil responding to a time-varying voltage/current
[0657] The force applied to the resonant mass may be measured in various
ways, examples of which may include but are not limited to: [0658]
measuring the pressure in the fixed volume; [0659] the resonant mass (not
shown) may be a piezoelectric material; and [0660] a strain gauge may be
connected to the diaphragm (not shown) or other structural member
supporting the resonant mass (not shown).
[0661] Similarly, the displacement of the resonant mass (not shown) may be
estimated by measuring the pressure in the variable volume, or measured
directly in various ways, examples of which may include but are not
limited to: [0662] via piezoelectric sensor; [0663] via capacitive
sensor; [0664] via optical sensor; [0665] via Hall-effect sensor; [0666]
via a potentiometer (time varying impedance) sensor; [0667] via an
inductive type sensor; and [0668] via a linear variable differential
transformer (LVDT)
[0669] Further, the resonant mass (not shown) may be integral to either
the force or displacement type sensor (i.e. the resonant mass (not shown)
may be made of piezoelectric material).
[0670] The application of force and measurement of displacement may be
accomplished by a single device. For example, a piezoelectric material
may be used for the resonant mass (not shown) and a time-varying
voltage/current may be applied to the piezoelectric material to create a
time-varying force. The resulting voltage/current applied to the
piezoelectric material may be measured and the transfer function between
the two used to estimate the natural frequency of volume sensor assembly
148.
[0671] As discussed above, the resonant frequency of volume sensor
assembly 148 may be estimated using swept-sine system identification.
Specifically, the above-described model fit may allow the resonant
frequency of the port assembly to be extracted from the sine sweep data,
which may then be used to determine the delivered volume. The ideal
relationship between the resonant frequency and the delivered volume may
be expressed as follows:
.omega. n 2 = a 2 A L 1 V 2 [ EQ #129
] ##EQU00097##
[0672] The speed of sound will vary with temperature, so it may be useful
to split out the temperature effects.
.omega. n 2 = .gamma. RA L T V 2 [ EQ
#130 ] ##EQU00098##
[0673] The volume may then be expressed as a function of the measured
resonant frequency and the temperature:
V 2 = C T .omega. n 2 [ EQ #131 ]
##EQU00099##
[0674] Where c is the calibration constant
C = .gamma. RA L . ##EQU00100##
[0675] Infusion pump assembly 100 may then compare this calculated volume
V.sub.2 (i.e., representative of the actual volume of infusible fluid
delivered to the user) to the target volume (i.e., representative of the
quantity of fluid that was supposed to be delivered to the user). For
example, assume that infusion pump assembly 100 was to deliver a 0.100
unit basal dose of infusible fluid to the user every thirty minutes.
Further, assume that upon effectuating such a delivery, volume sensor
assembly 148 indicates a calculated volume V.sub.2 (i.e., representative
of the actual volume of infusible fluid delivered to the user) of 0.095
units of infusible fluid.
[0676] When calculating volume V.sub.2, infusion pump assembly 100 may
first determine the volume of fluid within volume sensor chamber 620
prior to the administration of the dose of infusible fluid and may
subsequently determine the volume of fluid within volume sensor chamber
620 after the administration of the dose of infusible fluid, wherein the
difference of those two measurements is indicative of V.sub.2 (i.e., the
actual volume of infusible fluid delivered to the user). Accordingly,
V.sub.2 is a differential measurement.
[0677] V.sub.2 may be the total air space over the diaphragm in the
variable volume chamber. The actual fluid delivery to the patient may be
the difference in V2 from when the chamber was full to after the
measurement valve was opened and the chamber was emptied. V2 may not
directly be the delivered volume. For example, the air volume may be
measured and a series of differential measurements may be taken. For
occlusion, an empty measurement may be taken, the chamber may be filed, a
full measurement may be taken, and then a final measurement may be taken
after the exit valve is open. Accordingly, the difference between the
first and second measurement may be the amount pumped and the difference
between the second and third is the amount delivered to the patient.
[0678] Accordingly, electrical control assembly 110 may determine that the
infusible fluid delivered is 0.005 units under what was called for. In
response to this determination, electrical control assembly 110 may
provide the appropriate signal to mechanical control assembly 104 so that
any additional necessary dosage may be pumped. Alternatively, electrical
control assembly 110 may provide the appropriate signal to mechanical
control assembly 104 so that the additional dosage may be dispensed with
the next dosage. Accordingly, during administration of the next 0.100
unit dose of the infusible fluid, the output command for the pump may be
modified based on the difference between the target and amount delivered.
[0679] Referring also to FIG. 110, there is shown one particular
implementation of a control system for controlling the quantity of
infusible fluid currently being infused based, at least in part, on the
quantity of infusible fluid previously administered. Specifically and
continuing with the above-stated example, assume for illustrative
purposes that electrical control assembly 110 calls for the delivery of a
0.100 unit dose of the infusible fluid to the user. Accordingly,
electrical control assembly 110 may provide a target differential volume
signal 1600 (which identifies a partial basal dose of 0.010 units of
infusible fluid per cycle of shape memory actuator 112) to volume
controller 1602. Accordingly and in this particular example, shape memory
actuator 112 may need to be cycled ten times in order to achieve the
desired basal dose of 0.100 units of infusible fluid (i.e., 10
cycles.times.0.010 units per cycle=0.100 units). Volume controller 1602
in turn may provide "on-time" signal 1606 to SMA (i.e., shape memory
actuator) controller 1608. Also provided to SMA controller 1608 is
battery voltage signal 1610.
[0680] Specifically, shape-memory actuator 112 may be controlled by
varying the amount of thermal energy (e.g., joules) applied to
shape-memory actuator 112. Accordingly, if the voltage level of battery
606 is reduced, the quantity of joules applied to shape-memory actuator
112 may also be reduced for a defined period of time. Conversely, if the
voltage level of battery 606 is increased, the quantity of joules applied
to shape memory actuator 112 may also be increased for a defined period
of time. Therefore, by monitoring the voltage level of battery 606 (via
battery voltage signal 1610), the type of signal applied to shape-memory
actuator 112 may be varied to ensure that the appropriate quantity of
thermal energy is applied to shape-memory actuator 112 regardless of the
battery voltage level.
[0681] SMA controller 1608 may process "on-time" signal 1606 and battery
voltage signal 1610 to determine the appropriate SMA drive signal 1612 to
apply to shape-memory actuator 112. One example of SMA drive signal 1612
may be a series of binary pulses in which the amplitude of SMA drive
signal 1612 essentially controls the stroke length of shape-memory
actuator 112 (and therefore pump assembly 106) and the duty cycle of SMA
drive signal 1612 essentially controls the stroke rate of shape-memory
actuator 112 (and therefore pump assembly 106). Further, since SMA drive
signal 1612 is indicative of a differential volume (i.e., the volume
infused during each cycle of shape memory actuator 112), SMA drive signal
1612 may be integrated by discrete time integrator 1614 to generate
volume signal 1616 which may be indicative of the total quantity of
infusible fluid infused during a plurality of cycles of shape memory
actuator 112. For example, since (as discussed above) it may take ten
cycles of shape memory actuator 112 (at 0.010 units per cycle) to infuse
0.100 units of infusible fluid, discrete time integrator 1614 may
integrate SMA drive signal 1612 over these ten cycles to determine the
total quantity infused of infusible fluid (as represented by volume
signal 1616).
[0682] SMA drive signal 1612 may actuate pump assembly 106 for e.g. one
cycle, resulting in the filling of volume sensor chamber 620 included
within volume sensor assembly 148. Infusion pump assembly 100 may then
make a first measurement of the quantity of fluid included within volume
sensor chamber 620 (as discussed above). Further and as discussed above,
measurement valve assembly 610 may be subsequently energized, resulting
in all or a portion of the fluid within volume sensor chamber 620 being
delivered to the user. Infusion pump assembly 100 may then make a
measurement of the quantity of fluid included within volume sensor
chamber 620 (as described above) and use those two measurements to
determine V.sub.2 (i.e., the actual volume of infusible fluid delivered
to the user during the current cycle of shape memory actuator 112). Once
determined, V.sub.2 (i.e., as represented by signal 1618) may be provided
(i.e., fed back) to volume controller 1602 for comparison to the
earlier-received target differential volume.
[0683] Continuing with the above-stated example in which the differential
target volume was 0.010 units of infusible fluid, assume that V.sub.2
(i.e., as represented by signal 1618) identifies 0.009 units of infusible
fluid as having been delivered to the user. Accordingly, infusion pump
assembly 100 may increase the next differential target volume to 0.011
units to offset the earlier 0.001 unit shortage. Accordingly and as
discussed above, the amplitude and/or duty cycle of SMA drive signal 1612
may be increased when delivering the next basal dose of the infusible
fluid to the user. This process may be repeated for the remaining nine
cycles of shape memory actuator 112 (as discussed above) and discrete
time integrator 1614 may continue to integrate SMA drive signal 1612 (to
generate volume signal 1616) which may define the total quantity of
infusible fluid delivered to the user.
[0684] Referring also to FIG. 111, there is shown one possible embodiment
of volume controller 1602. In this particular implementation, volume
controller 1602 may include PI (proportional-integrator) controller 1650.
Volume controller 1602 may include feed forward controller 1652 for
setting an initial "guess" concerning "on-time" signal 1606. For example,
for the situation described above in which target differential volume
signal 1600 identifies a partial basal dose of 0.010 units of infusible
fluid per cycle of shape memory actuator 112, feed forward controller
1652 may define an initial "on-time" of e.g., one millisecond. Feed
forward controller 1652 may include e.g., a lookup table that define an
initial "on-time" that is based, at least in part, upon target
differential volume signal 1600. Volume controller 1602 may further
include discrete time integrator 1654 for integrating target differential
volume signal 1600 and discrete time integrator 1656 for integrating
V.sub.2 (i.e., as represented by signal 1618).
[0685] Referring also to FIG. 112, there is shown one possible embodiment
of feed forward controller 1652. In this particular implementation, feed
forward controller 1652 may define a constant value signal 1658 and may
include amplifier 1660 (e.g., a unity gain amplifier), the output of
which may be summed with constant value signal 1658 at summing node 1662.
The resulting summed signal (i.e., signal 1664) may be provided to as an
input signal to e.g., lookup table 1666, which may be processed to
generate the output signal of feed forward controller 1652.
[0686] As discussed above, pump assembly 106 may be controlled by shape
memory actuator 112. Further and as discussed above, SMA controller 1608
may process "on-time" signal 1606 and battery voltage signal 1610 to
determine the appropriate SMA drive signal 1612 to apply to shape-memory
actuator 112.
[0687] Referring also to FIGS. 113-114, there is shown one particular
implementation of SMA controller 1608. As discussed above, SMA controller
1608 may be responsive to "on-time" signal 1606 and battery voltage
signal 1610 and may provide SMA drive signal 1612 to shape-memory
actuator 112. SMA controller 1608 may include a feedback loop (including
unit delay 1700), the output of which may be multiplied with battery
voltage signal 1610 at multiplier 1702. The output of multiplier 1702 may
be amplified with e.g., unity gain amplifier 1704. The output of
amplifier 1704 may be applied to the negative input of summing node 1706
(to which "on-time" signal 1606 is applied). The output of summing node
1706 may be amplified (via e.g., unity gain amplifier 1708). SMA
controller may also include feed forward controller 1710 to provide an
initial value for SMA drive signal 1612 (in a fashion similar to feed
forward controller 1652 of volume controller 1602; See FIG. 112). The
output of feed forward controller 1710 may be summed at summing node 1712
with the output of amplifier 1708 and an integrated representation (i.e.,
signal 1714) of the output of amplifier 1708 to form SMA drive signal
1612.
[0688] SMA drive signal 1612 may be provided to control circuitry that
effectuates the application of power to shape-memory actuator 112. For
example, SMA drive signal 1612 may be applied to switching assembly 1716
that may selectively apply current signal 1718 (supplied from battery
606) and/or fixed signal 1720 to shape-memory actuator. For example, SMA
drive signal 1612 may effectuate the application of energy (supplied from
battery 606 via current signal 1718) via switching assembly 1716 in a
manner that achieves the duty cycle defined by SMA drive signal 1612.
Unit delay 1722 may generate a delayed version of the signal applied to
shape-memory actuator 112 to form battery voltage signal 1610 (which may
be applied to SMA controller 1608).
[0689] When applying power to shape-memory actuator 112, voltage may be
applied for a fixed amount of time and: a) at a fixed duty cycle with an
unregulated voltage; b) at a fixed duty cycle with a regulated voltage;
c) at a variable duty cycle based upon a measured current value; d) at a
variable duty cycle based upon a measured voltage value; and e) at a
variable duty cycle based upon the square of a measured voltage value.
Alternatively, voltage may be applied to shape-memory actuator 112 for a
variable amount of time based upon a measured impedance.
[0690] When applying an unregulated voltage for a fixed amount of time at
a fixed duty cycle, inner loop feedback may not be used and shape memory
actuator may be driven at a fixed duty cycle and with an on-time
determined by the outer volume loop.
[0691] When applying a regulated voltage for a fixed amount of time at a
fixed duty cycle, inner loop feedback may not be used and shape memory
actuator 112 may be driven at a fixed duty cycle and with an on-time
determined by the outer volume loop.
[0692] When applying an unregulated voltage at a variable duty cycle based
upon a measured current value, the actual current applied to shape-memory
actuator 112 may be measured and the duty cycle may be adjusted during
the actuation of shape-memory actuator 112 to maintain the correct mean
current.
[0693] When applying an unregulated voltage at a variable duty cycle based
upon a measured voltage value, the actual voltage applied to shape-memory
actuator 112 may be measured and the duty cycle may be adjusted during
the actuation of shape-memory actuator 112 to maintain the correct mean
voltage.
[0694] When applying an unregulated voltage at a variable duty cycle based
upon the square of a measured voltage value, the actual voltage applied
to shape-memory actuator 112 may be measured and the duty cycle may be
adjusted during the actuation of shape-memory actuator 112 to maintain
the square of the voltage at a level required to provide the desired
level of power to shape-memory actuator 112 (based upon the impedance of
shape-memory actuator 112).
[0695] Referring also to FIG. 114A-114B, there is shown other
implementations of SMA controller 1608. Specifically, FIG. 114A is an
electrical schematic that includes a microprocessor and various control
loops that may be configured to provide a PWM signal that may open and
close the switch assembly. The switch assembly may control the current
that is allowed to flow through the shape memory actuator. The battery
may provide the current to the shape memory actuator. Further, 114B
discloses a volume controller and an inner shape memory actuator
controller. The shape memory actuator controller may provide a PWM signal
to the pump, which may be modified based on the battery voltage. This may
occur for a fixed ontime, the result being a volume that may be measured
by volume sensor assembly 148 and fed back into the volume controller.
[0696] In our preferred embodiment, we vary the duty cycle based on the
measured battery voltage to give you approximately consistent power. We
adjust the duty cycle to compensate for a lower battery voltage. Battery
voltage may change for two reasons: 1) as batteries are discharged, the
voltage slowly decreases; and 2) when you apply a load to a battery it
has an internal impedance so its voltage dips. This is something that
happens in any type of system, and we compensate for that by adjusting
the duty cycle, thus mitigating the lower or varying battery voltage.
Battery voltage may be measured by the microprocessor. In other systems:
1) voltage may be regulated (put a regulator to maintain the voltage at a
steady voltage); 2) feedback based on something else (i.e., speed or
position of a motor, not necessarily measuring the battery voltage).
[0697] Other configurations may be utilized to control the shape memory
actuator. For example: A) the shape memory actuator may be controlled at
fixed duty cycle with unregulated voltage. As voltage varies, the
repeatability of heating the shape memory actuator is reduced. B) a fixed
duty cycle, regulated voltage may be utilized which compensate for
changes in battery voltage. However, regulate the voltage down is less
efficient due to energy of energy. C) the duty cycle may be varied based
on changes in current (which may required more complicated measurement
circuitry. D) The duty cycle may be varied based on measured voltage. E)
The duty cycle may be varied based upon the square of the current or the
square of the voltage divided by resistance. F) the voltage may be
applied for a variable amount of time based on the measured impedance
(e.g., may measure impedance using Wheatstone gauge (not shown)). The
impedance of the shape memory actuator may be correlated to strain (i.e.,
may correlate how much the SMA moves based on its impedance).
[0698] Referring also to FIG. 115 and as discussed above, to enhance the
safety of infusion pump assembly 100, electrical control assembly 110 may
include two separate and distinct microprocessors, namely supervisor
processor 1800 and command processor 1802. Specifically, command
processor 1802 may perform the functions discussed above (e.g.,
generating SMA drive signal 1612) and may control relay/switch assemblies
1804, 1806 that control the functionality of (in this example) shape
memory actuators 112, 632 (respectively). Command processor 1802 may
receive feedback from signal conditioner 1808 concerning the condition
(e.g., voltage level) of the voltage signal applied to shape memory
actuators 112, 632. Command processor 1800 may control relay/switch
assembly 1810 independently of relay/switch assemblies 1804, 1806.
Accordingly, when an infusion event is desired, both of supervisor
processor 1800 and command processor 1802 must agree that the infusion
event is proper and must both actuate their respective relays/switches.
In the event that either of supervisor processor 1800 and command
processor 1802 fails to actuate their respective relays/switches, the
infusion event will not occur. Accordingly through the use of supervisor
processor 1800 and command processor 1802 and the cooperation and
concurrence that must occur, the safety of infusion pump assembly 100 is
enhanced.
[0699] The supervisor processor may prevent the command processor from
delivering when it is not supposed and also may alarm if the command
processor does not deliver when it should be delivering. The supervisor
processor may deactivate the relay/switch assembly if the command
processor actuates the wrong switch, or if the command processor it tries
to apply power for too long.
[0700] The supervisor processor may redundantly doing calculations for how
much insulin should be delivered (i.e., double checking the calculations
of the command processor). Command processor may decide the delivery
schedule, and the supervisor processor may redundantly check those
calculations.
[0701] Supervisor also redundantly holds the profiles (delivery profiles)
in RAM, so the command processor may be doing the correct calculations,
but if is has bad RAM, would cause the command to come up with the wrong
result. The Supervisor uses its local copy of the basal profile, etc., to
double check.
[0702] Supervisor can double check AVS measurements, looks at the AVS
calculations and applies safety checks. Every time AVS measurement is
taken, it double checks.
[0703] Referring also to FIG. 116, one or more of supervisor processor
1800 and command processor 1802 may perform diagnostics on various
portions of infusion pump assembly 100. For example, voltage dividers
1812, 1814 may be configured to monitor the voltages (V1 & V2
respectively) sensed at distal ends of e.g., shape memory actuator 112.
The value of voltages V1 & V2 in combination with the knowledge of the
signals applied to relay/switch assemblies 1804, 1810 may allow for
diagnostics to be performed on various components of the circuit shown in
FIG. 116 (in a manner similar to that shown in illustrative diagnostic
table 1816).
[0704] As discussed above and as illustrated in FIGS. 115-116, to enhance
the safety of infusion pump assembly 100, electrical control assembly 110
may include a plurality of microprocessors (e.g., supervisor processor
1800 and command processor 1802), each of which may be required to
interact and concur in order to effectuate the delivery of a dose of the
infusible fluid. In the event that the microprocessors fail to
interact/concur, the delivery of the dose of infusible fluid may fail and
one or more alarms may be triggered, thus enhancing the safety and
reliability of infusion pump assembly 100.
[0705] A master alarm may be utilized that tracks the volume error over
time. Accordingly, if the sum of the errors becomes too large, the master
alarm may be initiated, indicating that something may be wrong with the
system. Accordingly, the master alarm may be indicative of a total volume
comparison being performed and a discrepancy being noticed. A typical
value of the discrepancy required to initiate the master alarm may be
1.00 milliliters. The master alarm may monitor the sum in a leaky fashion
(i.e., Inaccuracies have a time horizon).
[0706] Referring also to FIGS. 117A-117B, there is shown one such
illustrative example of such interaction amongst multiple microprocessors
during the delivery of a dose of the infusible fluid. Specifically,
command processor 1802 may first determine 1900 the initial volume of
infusible fluid within volume sensor chamber 620. Command processor 1802
may then provide 1902 a "pump power request" message to supervisor
processor 1800. Upon receiving 1904 the "pump power request" message,
supervisor processor 1800 may e.g., energize 1906 relay/switch 1810 (thus
energizing shape memory actuator 112) and may send 1908 a "pump power on"
message to command processor 1802. Upon receiving 1910 the "pump power
on" message, command processor 1802 may actuate 1912 e.g., pump assembly
106 (by energizing relay/switch 1804), during which time supervisor
processor 1800 may monitor 1914 the actuation of e.g., pump assembly 106.
[0707] Once actuation of pump assembly 106 is complete, command processor
1802 may provide 1914 a "pump power off" message to supervisor processor
1800. Upon receiving 1916 the "pump power off" message, supervisor
processor 1800 may deenergize 1918 relay/switch 1810 and provide 1920 a
"pump power off" message to command processor 1802. Upon receiving 1922
the "pump power off" message, command processor 1802 may measure 1924 the
quantity of infusible fluid pumped by pump assembly 106. This may be
accomplished by measuring the current quantity of fluid within volume
sensor chamber 620 and comparing it with the quantity determined above
(in step 1900). Once determined 1924, command processor 1802 may provide
1926 a "valve open power request" message to supervisor processor 1800.
Upon receiving 1928 the "valve open power request" message, supervisor
processor 1800 may energize 1930 relay/switch 1810 (thus energizing shape
memory actuator 632) and may send 1932 a "valve open power on" message to
command processor 1802. Upon receiving 1934 the "valve open power on"
message, command processor 1802 may actuate 1936 e.g., measurement valve
assembly 610 (by energizing relay/switch 1806), during which time
supervisor processor 1800 may monitor 1938 the actuation of e.g.,
measurement valve assembly 610.
[0708] Once actuation of measurement valve assembly 610 is complete,
command processor 1802 may provide 1940 a "valve power off" message to
supervisor processor 1800. Upon receiving 1942 the "valve power off"
message, supervisor processor 1800 may deenergize 1944 relay/switch 1810
and provide 1946 a "valve power off" message to command processor 1802.
[0709] Upon receiving 1948 the "valve power off" message, command
processor 1802 may provide 1950 a "valve close power request" message to
supervisor processor 1800. Upon receiving 1952 the "valve close power
request" message, supervisor processor 1800 may energize 1954
relay/switch 1810 (thus energizing shape memory actuator 652) and may
send 1956 a "power on" message to command processor 1802. Upon receiving
1958 the "power on" message, command processor 1802 may actuate 1960 an
energizing relay/switch (not shown) that is configured to energize shape
memory actuator 652, during which time supervisor processor 1800 may
monitor 1962 the actuation of e.g., shape memory actuator 652.
[0710] As discussed above (and referring temporarily to FIGS. 26A, 26B,
27A, 27B & 28), shape memory actuator 652 may be anchored on a first end
using electrical contact 654. The other end of shape memory actuator 652
may be connected to bracket assembly 656. When shape memory actuator 652
is activated, shape memory actuator 652 may pull bracket assembly 656
forward and release valve assembly 634. As such, measurement valve
assembly 610 may be activated via shape memory actuator 632. Once
measurement valve assembly 610 has been activated, bracket assembly 656
may automatically latch valve assembly 610 in the activated position.
Actuating shape memory actuator 652 may pull bracket assembly 656 forward
and release valve assembly 634. Assuming shape memory actuator 632 is no
longer activated, measurement valve assembly 610 may move to a
de-activated state once bracket assembly 656 has released valve assembly
634. Accordingly, by actuating shape memory actuator 652, measurement
valve assembly 610 may be deactivated.
[0711] Once actuation of shape memory actuator 652 is complete, command
processor 1802 may provide 1964 a "power off" message to supervisor
processor 1800. Upon receiving 1966 the "power off" message, supervisor
processor 1800 may deenergize 1968 relay/switch 1810 and may provide 1970
a "power off" message to command processor 1802. Upon receiving 1972 the
"power off" message, command processor 1802 may determine the quantity of
infusible fluid within volume sensor chamber 620, thus allowing command
processor 1802 to compare this measured quantity to the quantity
determined above (in step 1924) to determine 1974 the quantity of
infusible fluid delivered to the user.
[0712] In the event that the quantity of infusible fluid delivered 1974 to
the user is less than the quantity of infusible fluid specified for the
basal/bolus infusion event, the above-described procedure may be repeated
(via loop 1976).
[0713] Referring also to FIG. 118, there is shown another illustrative
example of the interaction amongst processors 1800, 1802, this time
during the scheduling of a dose of infusible fluid. Command processor
1802 may monitor 2000, 2002 for the receipt of a basal scheduling message
or a bolus request message (respectively). Upon receipt 2000, 2002 of
either of these messages, command processor 1802 may set 2004 the desired
delivery volume and may provide 2006 a "delivery request" message to
supervisor processor 1800. Upon receiving 2008 the "delivery request"
message, supervisor processor 1800 may verify 2010 the volume defined
2004 by command processor 1802. Once verified 2010, supervisor processor
1800 may provide 2012 a "delivery accepted" message to command processor
1802. Upon receipt 2014 of the "delivery accepted" message, command
processor 1802 may update 2016 the controller (e.g., the controller
discussed above and illustrated in FIG. 110) and execute 2018 delivery of
the basal/bolus dose of infusible fluid. Command processor 1808 may
monitor and update 2022 the total quantity of infusible fluid delivered
to the user (as discussed above and illustrated in FIGS. 117A-117B). Once
the appropriate quantity of infusible fluid is delivered to the user,
command processor 1802 may provide 2024 a "delivery done" message to
supervisor processor 1800. Upon receipt 2026 of the "delivery done"
message, supervisor processor 1800 may update 2028 the total quantity of
infusible fluid delivered to the user. In the event that the total
quantity of infusible fluid delivered 2018 to the user is less than the
quantity defined above (in step 2004), the infusion process discussed
above may be repeated (via loop 2030).
[0714] Referring also to FIG. 119, there is shown an example of the manner
in which supervisor processor 1800 and command processor 1802 may
interact while effectuating a volume measurements via volume sensor
assembly 148 (as described above).
[0715] Specifically, command processor 1802 may initialize 2050 volume
sensor assembly 148 and begin collecting 2052 data from volume sensor
assembly 148, the process of which may be repeated for each frequency
utilized in the above-described sine sweep. Each time that data is
collected for a particular sweep frequency, a data point message may be
provided 2054 from command processor 1802, which may be received 2056 by
supervisor processor 1800.
[0716] Once data collection 2052 is completed for the entire sine sweep,
command processor 1802 may estimate 2058 the volume of infusible fluid
delivered by infusion pump assembly 100. Command processor 1802 may
provide 2060 a volume estimate message to supervisor processor 1800. Upon
receiving 2062 this volume estimate message, supervisor processor 1800
may check (i.e., confirm) 2064 the volume estimate message. Once checked
(i.e., confirmed), supervisor processor 1800 may provide 2066 a
verification message to command processor 1802. Once received 2068 from
supervisor processor 1800, command processor 1802 may set the measurement
status for the dose of infusible fluid delivered by volume sensor
assembly 148.
[0717] As discussed above and referring temporarily to FIG. 11), the
various embodiments of the infusion pump assembly (e.g., infusion pump
assembly 100, 100', 400, 500) discussed above may be configured via a
remote control assembly 300. When configurable via remote control
assembly 300, the infusion pump assembly may include telemetry circuitry
(not shown) that allows for communication (e.g., wired or wireless)
between the infusion pump assembly and e.g., remote control assembly 300,
thus allowing remote control assembly 300 to remotely control the
infusion pump assembly. Remote control assembly 300 (which may also
include telemetry circuitry (not shown) and may be capable of
communicating with the infusion pump assembly) may include display
assembly 302 and input assembly 304. Input assembly 304 may include
slider assembly 306 and switch assemblies 308, 310. In other embodiments,
the input assembly may include a jog wheel, a plurality of switch
assemblies, or the like. Remote control assembly 300 may allow the user
to program basal and bolus delivery events.
[0718] Remote control assembly 300 may include two processors, one
processor (e.g., which may include, but is not limited to a CC2510
microcontroller/RF transceiver, available from Chipcon AS, of Oslo,
Norway) may be dedicated to radio communication, e.g., for communicating
with infusion pump assembly 100, 100', 400, 500. The second processor
included within remote control assembly (which may include but are not
limited to an ARM920T and an ARM922T manufactured by ARM Holdings PLC of
the United Kingdom) may be a command processor and may perform data
processing tasks associated with e.g., configuring infusion pump assembly
100, 100', 400, 500.
[0719] Further and as discussed above, one embodiment of electrical
control assembly 816 may include three microprocessors. One processor
(e.g., which may include, but is not limited to a CC2510
microcontroller/RF transceiver, available from Chipcon AS, of Oslo,
Norway) may be dedicated to radio communication, e.g., for communicating
with a remote control assembly 300. Two additional microprocessors (e.g.,
supervisor processor 1800 and command processor 1802) may effectuate the
delivery of the infusible fluid (as discussed above). Examples of
supervisor processor 1800 and command processor 1802 may include, but is
not limited to an MSP430 microcontroller, available from Texas
Instruments Inc. of Dallas, Tex.
[0720] The OS may be a non-preemptive scheduling system, in that all tasks
may run to completion before the next task is allowed to run regardless
of priority. Additionally, context switches may not be performed. When a
task completes executing, the highest priority task that is currently
scheduled to run may then be executed. If no tasks are scheduled to
execute, the OS may place the processor (e.g., supervisor processor 1800
and/or command processor 1802) into a low power sleep mode and may wake
when the next task is scheduled. The OS may only be used to manage main
loop code and may leave interrupt-based functionality unaffected.
[0721] The OS may be written to take advantage of the C++ language.
Inheritance as well as virtual functions may be key elements of the
design, allowing for easy creation, scheduling and managing of tasks.
[0722] At the base of the OS infrastructure may be the ability to keep
track of system time and controlling the ability to place the processor
in Low Power Mode (LPM; also known as sleep mode). This functionality
along with the control and configuration of all system clocks, ay be
encapsulated by the SysClocks class.
[0723] The SysClocks class may contain the functionality to place the
processor (e.g., supervisor processor 1800 and/or command processor 1802)
into LPM to reduce energy consumption. While in LPM, the slow real time
clock may continue to run while the fast system clock that runs the CPU
core and most peripherals may be disabled.
[0724] Placing the processor into LPM may always be done by the provided
SysClocks function. This function may contain all required power down and
power up sequences resulting in consistency whenever entering or exiting
LPM. Waking from LPM may be initiated by any interrupts based on the slow
clock.
[0725] The OS may keep track of three aspects of time: seconds,
milliseconds and the time of day. Concerning seconds, SysClocks may count
seconds starting when the processor comes out of reset. The second
counter may be based on the slow system clocks and, therefore, may
increment regardless of whether the processor is in LPM or at full power.
As a result, it is the boundary at which the processor may wake from
sleep to execute previously scheduled tasks. If a task is scheduled to
run immediately from an interrupt service routine (ISR), the ISR may wake
the processor from LPM on exit and the task may be executed immediately.
Concerning milliseconds, in addition to counting the seconds since power
on, SysClocks may also count milliseconds while the processor is in full
power mode. Since the fast clock is stopped during LPM, the millisecond
counter may not increment. Accordingly, whenever a task is scheduled to
execute based on milliseconds, the processor may not enter LPM.
Concerning time of day, the time of day may be represented within
SysClocks as seconds since a particular point time (e.g., seconds since 1
Jan. 2004).
[0726] The SysClocks class may provide useful functionality to be used
throughout the Command and Supervisor project code base. The code delays
may be necessary to allow hardware to settle or actions to be completed.
SysClocks may provide two forms of delays, a delay based on seconds or a
delay based on milliseconds. When a delay is used, the processor may
simply wait until the desired time has passed before continue with its
current code path. Only ISRs may be executed during this time. SysClocks
may provide all of the required functionality to set or retrieve the
current time of day.
[0727] The word "task" may be associated with more complex scheduling
systems; therefore within the OS, task may be represented by and referred
to as Managed Functions. The ManagedFunc class may be an abstract base
class that provides all the necessary control members and functionality
to manage and schedule the desired functionality.
[0728] The ManagedFunc base class may have five control members, two
scheduling manipulation member functions, and one pure virtual execute
function that may contain the managed functionality. All of the
ManagedFunc control members may be hidden from the derived class and may
only be directly set by the derived class during creation, thus
simplifying the use and enhancing the safety of infusion pump assembly
100, 100', 400, 500.
[0729] The Function ID may be set at the time of creation and may never be
changed. All Function IDs may be defined within a single .h file, and the
base ManagedFunc constructor may strongly enforce that the same ID may
not be used for more than one managed function. The ID may also define
the priority of a function (with respect to other functions) based upon
the function ID assigned, wherein higher priority functions are assigned
lower function IDs. The highest priority task that is currently scheduled
to execute may execute before lower priority tasks.
[0730] All other control members may be used to represent the function's
current scheduled state, when it should be executed, and if (upon
execution) the function should be rescheduled to execute in a previously
set amount of time. Manipulation of these controls and states may be
allowed but only through the public member functions (thus enforcing
safety controls on all settings).
[0731] To control the scheduling of a managed function, the set start and
set repeat functions may be used. Each of these member functions may be a
simple interface allowing the ability to configure or disable repeat
settings as well as control whether a managed function is inactive,
scheduled by seconds, milliseconds, or time of day.
[0732] Through inheritance, creating a Managed Function may be done by
creating a derived class and defining the pure virtual `execute` function
containing the code that needs to be under scheduling control. The
ManagedFunc base class constructor may be based upon the unique ID of a
function, but may also be used to set default control values to be used
at start up.
[0733] For example to create a function that runs thirty seconds after
start up and every 15 seconds thereafter, the desired code is placed into
the virtual execute function and the function ID, scheduled by second
state, thirty second start time, and repeat setting of fifteen seconds is
provided to the constructor.
[0734] The following is an illustrative code example concerning the
creation of a managed function. In this particular example, a "heartbeat"
function is created that is scheduled to execute for the first time one
second after startup of infusion pump assembly 100, 100', 400, 500 and
execute every ten seconds thereafter:
TABLE-US-00011
#include "ManagedFunc.h"
// The SendGoodFunc is a "heartbeat" status message
class SendGoodFunc : public ManagedFunc
{
public:
// Initialize the managed func to run 2 seconds after
start up
// and repeat every second.
SendGoodFunc( ) :
ManagedFunc(IPC_SEND_GOOD, SCHEDULED_SEC, 1, true,
10) { };
~SendGoodFunc( ) { };
protected:
void execute(void);
};
void SendGoodFunc::execute(void)
{
// << code to send the heartbeat >>
}
SendGoodFunc g_sendGoodFunc;
// to manipulate the heartbeat timing simply call:
// g_sendGoodFunc.setFuncStart(...) or
g_sendGoodFunc.setRepeat( ... )
[0735] The actual execution of the Managed Functions may be controlled and
performed by the SleepManager class. The SleepManager may contain the
actual prioritized list of managed functions. This prioritized list of
functions may automatically be populated by the managed function creation
process and may ensure that each function is created properly and has a
unique ID.
[0736] The main role of the SleepManager class may be to have its `manage`
function called repeatedly from the processors main loop and/or from a
endless while loop. Upon each call of manage, the SleepManager may
execute all functions that are scheduled to run until the SleepManager
has exhausted all scheduled functions; at which time the SleepManager may
place the processor in LPM. Once the processor wakes from LPM, the manage
function may be reentered until the processor is again ready to enter LPM
(this process may be repeated until stopped, e.g., by a user or by the
system).
[0737] If the processor has to be kept in full power mode for an extended
period of time (e.g., while an analog-to-digital conversion is being
sampled), the SleepManager may provide functionality to disable entering
LPM. While LPM is disabled, the manage function may continuously search
for a scheduled task.
[0738] The SleepManager may also provide an interface to manipulate the
scheduling and repeat settings of any managed function through the use of
the unique ID of the function, which may allow any section of code to
perform any required scheduling without having direct access to or
unnecessary knowledge of the desired ManagedFunc object.
[0739] Radio circuitry included within each of infusion pump assembly 100,
100', 400, 500 and remote control assembly 300 may effectuate wireless
communication between remote control assembly 300 and infusion pump
assembly 100, 100', 400, 500. A 2.4 GHz radio communications chip (e.g.,
a Texas Instruments CC2510 radio transceiver) with an internal 8051
microcontroller may be used for radio communications.
[0740] The radio link may balance the following three objectives: link
availability; latency; and energy.
[0741] Concerning link availability, remote control assembly 300 may
provide the primary means for controlling the infusion pump assembly 100,
100', 400, 500 and may provide detailed feedback to the user via the
graphical user interface (GUI) of remote control assembly 300. Concerning
latency, the communications system may be designed to provide for low
latency to deliver data from remote control assembly 300 to the infusion
pump assembly 100, 100', 400, 500 (and vice versa). Concerning energy,
both remote control assembly 300 and infusion pump assembly 100, 100',
400, 500 may have a maximum energy expenditure for radio communications.
[0742] The radio link may support half-duplex communications. Remote
control assembly 300 may be the master of the radio link, initiating all
communications. Infusion pump assembly 100, 100', 400, 500 may only
respond to communications and may never initiate communications. The use
of such a radio communication system may provide various benefits, such
as: increased security: a simplified design (e.g., for airplane use); and
coordinated control of the radio link.
[0743] Referring also to FIG. 120A, there is shown one illustrative
example of the various software layers of the radio communication system
discussed above.
[0744] The radio processors included within remote control assembly 300
and infusion pump assembly 100, 100', 400, 500 may transfer messaging
packets between an SPI port and a 2.4 GHz radio link (and vice versa).
The radio may always be the SPI slave. On infusion pump assembly 100,
100', 400, 500, radio processor (PRP) 1818 (See FIGS. 115-116) may
service two additional nodes over the SPI port that are upstream (namely
command processor 1800 and supervisor processor 1802. In some
embodiments, on remote control assembly 300, the radio processor (CRP)
may service at least one additional node over the SPI port that may be
either upstream or down stream, for example, in some embodiments, the
above-described remote control processor (UI) and the Continuous Glucose
Engine (CGE).
[0745] A messaging system may allow for communication of messages between
various nodes in the network. The UI processor of remote control assembly
300 and e.g., supervisor processor 1800 may use the messaging system to
configure and initiate some of the mode switching on the two system
radios. It may be also used by the radios to convey radio and link status
information to other nodes in the network.
[0746] When the radio of remote control assembly 300 wishes to gather
channel statistics from the infusion pump assembly 100, 100', 400, 500 or
update the master channel list of the radio of infusion pump assembly
100, 100', 400, 500, the radio of remote control assembly 300 may use
system messages. Synchronization for putting the new updated list into
effect may use indicators in the heartbeat messages to remove timing
uncertainty.
[0747] The radio communication system may be written in C++ to be
compatible with the messaging software. A four byte radio serial number
may be used to address each radio node. A hash table may be used to
provide a one-to-one translation between the device "readable" serial
number string and the radio serial number. The hash table may provide a
more randomized 8-bit logical address so that pumps (e.g., infusion pump
assembly 100, 100', 400, 500) or controllers with similar readable serial
numbers are more likely to have unique logical addresses. Radio serial
numbers may not have to be unique between pumps (e.g., infusion pump
assembly 100, 100', 400, 500) and controllers due to the unique roles
each has in the radio protocol.
[0748] The radio serial number of remote control assembly 300 and the
radio serial number of infusion pump assembly 100, 100', 400, 500 may be
included in all radio packets except for the RF Pairing Request message
that may only include the radio serial number of remote control assembly
300, thus ensuring that only occur with the remote control
assembly/infusion pump assembly to which it is paired. The CC2510 may
support a one byte logical node address and it may be advantageous to use
one byte of the radio serial number as the logical node address to
provide a level of filtering for incoming packets.
[0749] The Quiet_Radio signal may be used by the UI processor of remote
control assembly 300 to prevent noise interference on the board of remote
control assembly 300 by other systems on the board. When Quiet_Radio is
asserted, the radio application of remote control assembly 300 may send a
message to the radio of infusion pump assembly 100, 100', 400, 500
asserting Radio Quiet Mode for a pre-determined period of time. The
Quiet_Radio feature may not be required based on noise interference
levels measured on the PC board of remote control assembly 300. During
this period of time, the radio of remote control assembly 300 may stay in
Sleep Mode 2 for up to a maximum of 100 ms. The radio of remote control
assembly 300 may come out of Sleep Mode 2 when the Quiet_Radio signal is
de-asserted or the maximum time period has expired. The UI processor of
remote control assembly 300 may assert Quiet_Radio at least one radio
communication's interval before the event needs to be asserted. The radio
of remote control assembly 300 may inform the radio of infusion pump
assembly 100, 100', 400, 500 that communications will be shutdown during
this quiet period. The periodic radio link protocol may have status
bits/bytes that accommodate the Quiet_Radio feature unless Quiet_Radio is
not required.
[0750] The radio software may integrate with the messaging system and
radio bootloader on the same processor, and may be verified using a
throughput test. The radio software may integrate with the messaging
system, SPI Driver using DMA, and radio bootloader, all on the same
processor (e.g., the TI CC2510).
[0751] The radio of remote control assembly 300 may be configured to
consume no more than 32 mAh in three days (assuming one hundred minutes
of fast heartbeat mode communications per day). The radio of infusion
pump assembly 100, 100', 400, 500 may be configured to consume no more
than 25 mAh in three days (assuming one hundred minutes of fast heartbeat
mode communications per day).
[0752] The maximum time to reacquire communications may be .ltoreq.6.1
seconds including connection request mode and acquisition mode. The radio
of remote control assembly 300 may use the fast heartbeat mode or slow
heartbeat mode setting to its advantage in order to conserve power and
minimize latency to the user. The difference between the infusion pump
assembly 100, 100', 400, 500 and remote control assembly 300 entering
acquisition mode may be that the infusion pump assembly 100, 100', 400,
500 needs to enter acquisition mode often enough to ensure communications
may be restored within the maximum latency period. However, the remote
control assembly 300 may change how often to enter acquisition mode with
the infusion pump assembly 100, 100', 400, 500 when in slow heartbeat
mode and heartbeats are lost. The radio of remote control assembly 300
may have knowledge of the user GUI interaction, but the infusion pump
assembly 100, 100', 400, 500 may not.
[0753] The radio of remote control assembly 300 may set the heartbeat
period for both radios. The period may be selectable in order to optimize
power and link latency depending on activity. The desired heartbeat
period may be communicated in each heartbeat from the radio of remote
control assembly 300 to the radio of infusion pump assembly 100, 100',
400, 500. This may not exclusively establish the heartbeat rate of
infusion pump assembly 100, 100', 400, 500 due to other conditions that
determine what mode to be in. When in fast heartbeat mode, the radio of
remote control assembly 300 may set the heartbeat period to 20 ms if data
packets are available to send or receive, thus providing low link latency
communications when data is actively being exchanged.
[0754] When in fast heartbeat mode, the radio of remote control assembly
300 may set the heartbeat period to 60 ms four heartbeats after a data
packet was last exchanged in either direction on the radio. Keeping the
radio heartbeat period short after a data packet has been sent or
received may assure that any data response packet may be also serviced
using a low link latency. When in slow heartbeat mode, the heartbeat rate
may be 2.00 seconds or 6.00 second, depending upon online or offline
status respectively.
[0755] The infusion pump assembly 100, 100', 400, 500 may use the
heartbeat rate set by the radio of remote control assembly 300. The radio
of remote control assembly 300 may support the following mode requests
via the messaging system: [0756] Pairing Mode [0757] Connection Mode
[0758] Acquisition Mode (includes the desired paired infusion pump
assembly 100, 100', 400, 500 radio serial number) [0759] Sync Mode--Fast
Heartbeat [0760] Sync Mode--Slow Heartbeat [0761] RF Off Mode
[0762] The radio of infusion pump assembly 100, 100', 400, 500 may support
the following mode requests via the messaging system: [0763] Pairing
Mode [0764] Acquisition Mode [0765] RF Off Mode
[0766] The radio may use a system message to obtain the local radio serial
number. On remote control assembly 300, the radio may get the serial
number from the UI processor of remote control assembly 300. The radio
may use a system message to store the paired radio serial number.
[0767] Remote control assembly 300 and the radio of infusion pump assembly
100, 100', 400, 500 may issue a status message using the messaging system
to the UI processor of remote control assembly 300 and command processor
1802 whenever the following status changes: [0768] Online Fast:
Successful connection [0769] Online Fast: Change from Acquisition Mode to
Fast Heartbeat Mode [0770] Online Slow: Successful request change from
Fast Heartbeat to Slow Heartbeat [0771] Offline: Automatic change to
Search Sync mode due to lack of heartbeat exchanges. [0772] Online Fast:
Successful request change from Slow Heartbeat to Fast Heartbeat [0773]
Offline: Bandwidth falls below 10% in Sync Mode [0774] Online: Bandwidth
rises above 10% in Search Sync mode [0775] Offline: Successful request
change to RF Off Mode
[0776] The radio configuration message may be used to configure the number
of radio retries. This message may be sent over the messaging system. The
UI processor of remote control assembly 300 will send this command to
both the radio of remote control assembly 300 and the radio of infusion
pump assembly 100, 100', 400, 500 to configure these radio settings.
[0777] There may be two parameters in the radio configuration message:
namely the number of RF retries (e.g., the value may be from 0 to 10);
and the radio offline parameters (e.g., the value may be from 1 to 100 in
percent of bandwidth).
[0778] The radio application on both the remote control assembly 300 and
infusion pump assembly 100, 100', 400, 500 may have an API that allows
the messaging system to configure the number of RF retries and radio
offline parameters.
[0779] The following parameters may be recommended for the radio hardware
configuration: [0780] Base Radio Specifications [0781] MSK [0782] 250
kbps over air baud rate [0783] Up to 84 channels [0784] Channel spacing
1000 kHz [0785] Filter bandwidth 812 kHz [0786] No Manchester encoding
[0787] Data whitening [0788] 4 byte preamble [0789] 4 byte sync (word)
[0790] CRC appended to packet [0791] LQI (Link Quality Indicator)
appended to packet [0792] Automatic CRC filtering enabled
[0793] Forward Error Correction (FEC) may or may not be utilized. Although
Forward Error Correction (FEC) may be used to increase the effective
signal dynamic range by approximately 3 dB, FEC requires fixed packet
sizes and doubles the number of over the air bits for the same fixed size
message.
[0794] The radio may function within 1.83 meters distance under nominal
operating conditions (except in pairing mode). It may be a goal that the
radio function within 7.32 meters distance under nominal operating
conditions. The transmit power level may be 0 dBm (except in pairing
mode) and the transmit power level in pairing mode may be -22 dBm. Since
the desired radio node address of infusion pump assembly 100, 100', 400,
500 may be not known by the remote control assembly 300 in pairing mode,
both infusion pump assembly 100, 100', 400, 500 and remote control
assembly 300 may use a lower transmit power to reduce the likelihood of
inadvertently pairing with another infusion pump assembly.
[0795] AES Encryption may be used for all packets but may not be required,
as the Texas Instruments CC2510 radio transceiver includes this
functionality. If AES encryption is used, fixed keys may be utilized, as
fixed keys provide a quick way to enable encryption without passing keys.
However, key exchange may be provided for in future versions of infusion
pump assembly 100, 100', 400, 500. The fixed keys may be contained in one
separate header source file with no other variables but the fixed keys
data, thus allowing for easier management of read access of the file.
[0796] The radio software may support the following eight modes: [0797]
Pairing Mode [0798] RF Off Mode [0799] Connection Mode [0800] Acquisition
Mode [0801] Fast Heartbeat Mode [0802] Slow Heartbeat Mode [0803] Search
Sync Mode [0804] Sync'ed Acquisition Mode
[0805] which are graphically depicted in FIGS. 120B-120C.
[0806] Pairing may be the process of exchanging radio serial numbers
between remote control assembly 300 and infusion pump assembly 100, 100',
400, 500. Remote control assembly 300 may be "paired" with infusion pump
assembly 100, 100', 400, 500 when infusion pump assembly 100, 100', 400,
500 knows its serial number. Infusion pump assembly 100, 100', 400, 500
may be "paired" with remote control assembly 300 when remote control
assembly 300 knows its serial number.
[0807] Pairing mode (which is graphically depicted in FIG. 120D) may
require that four messages to be exchanged over the RF link: [0808] RF
Pairing Request (broadcast from Remote control assembly 300 to any
Infusion pump assembly 100, 100', 400, 500) [0809] RF Pairing Acknowledge
(from Infusion pump assembly 100, 100', 400, 500 to Remote control
assembly 300) [0810] RF Pairing Confirm Request (from Remote control
assembly 300 to Infusion pump assembly 100, 100', 400, 500) [0811] RF
Pairing Confirm Acknowledge (from Infusion pump assembly 100, 100', 400,
500 to Remote control assembly 300)
[0812] Additionally, remote control assembly 300 may cancel the pairing
process at any time via the RF pairing abort message (from remote control
assembly 300 to infusion pump assembly 100, 100', 400, 500. Pairing mode
may not support messaging system data transfers.
[0813] The radio of infusion pump assembly 100, 100', 400, 500 may enter
pairing mode upon receiving a pairing mode request message. It may be the
responsibility of supervisor processor 1800 on infusion pump assembly
100, 100', 400, 500 to request the radio to enter pairing mode if there
is no disposable attached to infusion pump assembly 100, 100', 400, 500
and the user has pressed the button of infusion pump assembly 100, 100',
400, 500 for six seconds. The radio of infusion pump assembly 100, 100',
400, 500 may set the appropriate transmit power level for pairing mode.
Infusion pump assembly 100, 100', 400, 500 may only be paired with one
remote control assembly 300 at a time.
[0814] Upon receiving the first valid RF pairing request message while in
pairing mode, the radio of infusion pump assembly 100, 100', 400, 500 may
use the serial number of remote control assembly 300 for the duration of
pairing mode and respond with an RF pairing acknowledge message
containing the radio serial number infusion pump assembly 100, 100', 400,
500.
[0815] The radio of infusion pump assembly 100, 100', 400, 500 may timeout
of pairing mode automatically after 2.0.+-.0.2 seconds if no RF pairing
request is received. The radio of infusion pump assembly 100, 100', 400,
500 may issue a pairing request received message after transmitting the
RF pairing acknowledge. This message to supervisor processors will allow
feedback to the user during the pairing confirm process. The radio of
infusion pump assembly 100, 100', 400, 500 may automatically timeout of
pairing mode in 1.0.+-.0.1 minutes after sending an RF pairing
acknowledge unless an RF pairing confirm request is received. The radio
of infusion pump assembly 100, 100', 400, 500 may issue a store paired
radio serial number message if an RF pairing confirm request message is
received after receiving a RF pairing request message. This action may
store the radio serial number of remote control assembly 300 in the
non-volatile memory of infusion pump assembly 100, 100', 400, 500 and may
overwrite the existing pairing data for the infusion pump assembly 100,
100', 400, 500.
[0816] The radio of infusion pump assembly 100, 100', 400, 500 may
transmit an RF pairing confirm acknowledge and exit pairing mode after
the acknowledgment from the store paired radio serial number message is
received. This may be the normal exit of pairing mode on infusion pump
assembly 100, 100', 400, 500 and may result in infusion pump assembly
100, 100', 400, 500 powering down until connection mode or paring mode
entered by the user.
[0817] If the radio of infusion pump assembly 100, 100', 400, 500 exits
pairing mode upon successfully receiving a pairing confirm request
message, then the radio of infusion pump assembly 100, 100', 400, 500 may
revert to the newly paired remote control assembly 300 and may send a
pairing completion success message to command processor 1802. The radio
of infusion pump assembly 100, 100', 400, 500 may exit pairing mode upon
receiving an RF pairing abort message. The radio of infusion pump
assembly 100, 100', 400, 500 may exit pairing mode upon receiving a
pairing abort request message addressed to it. This may allow command
processor 1802 or supervisor processor 1800 to abort the pairing process
locally on the infusion pump assembly 100, 100', 400, 500.
[0818] The radio of remote control assembly 300 may enter pairing mode
upon receiving a pairing mode request message. It may be the
responsibility of the UI processor of remote control assembly 300 to
request that the radio enter pairing mode under the appropriate
conditions. The radio of remote control assembly 300 may set the
appropriate transmit power level for pairing mode. The radio of remote
control assembly 300 may transmit RF pairing requests until an RF pairing
acknowledge is received or pairing is aborted.
[0819] The radio of remote control assembly 300 may automatically abort
pairing mode if the RF pairing acknowledge message is not received within
30.0.+-.1.0 seconds after entering pairing mode. Upon receiving the first
valid RF pairing acknowledge message while in pairing mode, the radio of
remote control assembly 300 may send a pairing success message to the UI
processor of remote control assembly 300 that includes the serial number
of infusion pump assembly 100, 100', 400, 500 and may use that serial
number for the duration of pairing mode. This message may provide a means
for the UI processor of remote control assembly 300 to have the user
confirm the serial number of the desired infusion pump assembly 100,
100', 400, 500. If the radio of remote control assembly 300 receives
multiple responses (concerning a single pairing request) from infusion
pump assembly 100, 100', 400, 500, the first valid one may be used.
[0820] The Radio of remote control assembly 300 may only accept an RF
pairing confirm acknowledge messages after an RF pairing acknowledge is
received while in pairing mode. The radio of remote control assembly 300
may transmit the RF pairing confirm message upon receiving a pair confirm
request message from the UI processor of remote control assembly 300.
[0821] The radio of remote control assembly 300 may check that infusion
pump assembly 100, 100', 400, 500 confirms the pairing before adding
infusion pump assembly 100, 100', 400, 500 to the pairing list. The radio
of remote control assembly 300 may issue a store paired radio serial
number message if an RF pairing complete message is received. This action
may allow the UI processor of remote control assembly 300 to store the
new serial number of infusion pump assembly 100, 100', 400, 500 and
provide user feedback of a successful pairing. It may be the
responsibility of the UI processor of remote control assembly 300 to
manage the list of paired infusion pump assemblies.
[0822] The radio of remote control assembly 300 may send an RF pairing
abort message and exit pairing mode upon receiving a pairing abort
request message. This may allow the UI processor of the remote control
assembly 300 to abort the pairing process on both the remote control
assembly 300 and acknowledged infusion pump assembly 100, 100', 400, 500.
[0823] In connection request mode, the radio of remote control assembly
300 may attempt to acquire each infusion pump assembly 100, 100', 400,
500 in its paired infusion pump assembly list and retrieve its
"connection ready" status. The "connection" process (which is graphically
depicted in FIG. 120E) may allow remote control assembly 300 to quickly
identify one of its paired infusion pump assemblies that may be ready to
be used. The radio of remote control assembly 300 may be capable of
performing the connection request mode with up to six paired infusion
pump assemblies. Connection request mode may be only supported on remote
control assembly 300 and may be a special form of acquisition mode. In
connection request mode, remote control assembly 300 may connect with the
first infusion pump assembly to respond. However, each message may be
directed to a specific infusion pump assembly serial number.
[0824] The radio of remote control assembly 300 may obtain the latest
paired infusion pump assembly serial number list upon entering connection
mode. The radio of remote control assembly 300 may enter connection mode
upon receiving a connection mode request message. It may be the
responsibility of the UI processor of remote control assembly 300 to
request that the radio enter connection mode when it desires
communications with a paired infusion pump assembly. The radio of remote
control assembly 300 may issue a connection assessment message to the UI
processor of remote control assembly 300 containing the radio serial
number of the first infusion pump assembly, if any, that is "connection
ready". The radio of remote control assembly 300 may generate the
connection assessment message within thirty seconds of entering
connection request mode. The radio of remote control assembly 300 may
exit connection request mode upon receipt of the connection assessment
acknowledgement and transition to fast heartbeat mode. The radio of
remote control assembly 300 may exit connection request mode upon receipt
of a connection request abort message from the UI processor of remote
control assembly 300.
[0825] On remote control assembly 300, acquisition mode may be used to
find a particular paired infusion pump assembly. The radio of remote
control assembly 300 may send RF RUT (aRe yoU There) packets to the
desired paired infusion pump assembly. If the infusion pump assembly
receives the RF RUT message, it may respond to the radio of remote
control assembly 300. Multiple channels may be used in the acquisition
mode algorithm to improve the opportunity for the radio of remote control
assembly 300 to find the paired infusion pump assembly.
[0826] The radio of remote control assembly 300 may enter acquisition mode
upon receiving an acquisition mode request or fast heartbeat mode request
message while in RF Off Mode. The radio of remote control assembly 300
may enter sync'ed acquisition mode upon receiving an acquisition mode
request or fast heartbeat mode request message while in search sync mode.
It may be the responsibility of the UI processor of remote control
assembly 300 to request that the radio enter acquisition mode when the RF
link is off-line and remote control assembly 300 desires communications
with infusion pump assembly 100, 100', 400, 500.
[0827] The radio of remote control assembly 300 may only communicate with
one paired infusion pump assembly 100, 100', 400, 500 (except in pairing
and connection modes). When communications are lost, the UI processor of
remote control assembly 300 may use acquisition mode (at some periodic
rate limited by the power budget) to attempt to restore communications.
[0828] Infusion pump assembly 100, 100', 400, 500 may enter acquisition
mode under the following conditions: [0829] When in Radio Off Mode and
Acquisition Mode may be requested [0830] When Search Sync Mode times out
due to lack of heartbeats
[0831] Upon entering acquisition mode, the radio of infusion pump assembly
100, 100', 400, 500 may obtain the serial number of the last stored
paired remote control assembly 300. The radio of infusion pump assembly
100, 100', 400, 500 may only communicate with the remote control assembly
to which it has been "paired" (except while in the "pairing request"
mode). The radio of infusion pump assembly 100, 100', 400, 500 may
transition from acquisition mode to fast heartbeat mode upon successfully
acquiring synchronization with the remote control assembly 300. The
acquisition mode of infusion pump assembly 100, 100', 400, 500 may be
capable of acquiring synchronization within 6.1 seconds, which may
implies that the infusion pump assembly 100, 100', 400, 500 may always be
listening at least every .about.6 seconds when in acquisition mode.
[0832] Data packets may be sent between two paired devices when the two
devices are in sync mode and online. The two devices may sync via a
heartbeat packet before data packets are exchanged. Each radio may send
data packets at known time intervals after the heartbeat exchange. The
infusion pump assembly 100, 100', 400, 500 may adjust its timing to
anticipate reception of a packet. The radio may support one data packet
in each direction on each heartbeat. The radio may provide a negative
response to a fast heartbeat mode request if the radio if offline. The
radio of remote control assembly 300 may change to fast heartbeat mode if
a system request for fast heartbeat mode is received while in slow
heartbeat mode and the radio is online.
[0833] Upon transitioning to fast heartbeat mode from acquisition mode,
the radio of remote control assembly 300 may send the master channel list
message. The master channel list may be built by the radio of remote
control assembly 300 and sent to the radio of infusion pump assembly 100,
100', 400, 500 to allow a selection of frequency hopping channels based
on historical performance. When in fast heartbeat mode or slow heartbeat
mode, periodic heartbeat messages may be exchanged between the radio of
remote control assembly 300 and the radio of infusion pump assembly 100,
100', 400, 500. The periodicity of these messages may be at the heartbeat
rate. The heartbeat messages may allow data packet transfers to take
place and may also exchange status information. The two radios may
exchange the following status information: Quiet Mode, data availability,
buffer availability, heartbeat rate, and prior channel performance. It
may be a goal to keep the packet size of the heartbeat messages small in
order to conserve power. The radio may provide for a maximum data packet
size of eighty-two bytes when in Sync Mode. The messaging system may be
designed to support packet payload sizes up to sixty-four bytes. This
maximum size was selected as an optimal trade-off between minimum
messages types and non-fragmented messages. The eighty-two bytes may be
the maximum packet size of the messaging system including packet
overhead.
[0834] The messaging system has an API that may allow the radio protocol
to send an incoming radio packet to it. The messaging system may also
have an API that allows the radio protocol to get a packet for
transmission over the radio network. The messaging system may be
responsible for packet routing between the radio protocol and the SPI
port. Data packets may be given to the messaging system for processing.
The messaging system may have an API that allows the radio protocol to
obtain a count of the number of data packets waiting to be sent over the
radio network.
[0835] The radio protocol may query the messaging system on each heartbeat
to determine if data packets are available to send over the radio
network. It may be desirable for the software to check the availability
of a message just before the heartbeat is sent to minimize round trip
message latency. The radio protocol may be capable of buffering one
incoming radio data packet and passing the packet to the messaging
system. The radio protocol may send the data packet to the messaging
system upon receipt of the data packet. The message system may be
responsible for routing radio data packets to the proper destination
node. The radio protocol may be capable of buffering one packet from the
messaging system.
[0836] The radio protocol may be responsible for acknowledging receipt of
valid data packets over the RF link via an RF ACK reply packet to the
sending radio. The RF ACK packet may contain the source and destination
radio serial numbers, RF ACK command identification, and sequence number
of the data packet being acknowledged.
[0837] The radio transmitting a radio data packet may retransmit that
radio data packet on the next heartbeat with the same sequence number if
an RF ACK is not received and the retry count is within the maximum RF
retries allowed. It may be expected that, from time to time, interference
will corrupt a transmission on a particular frequency. An RF retry allows
the same packet to be retransmitted at the next opportunity at a
different frequency. The sequence number provides a means of uniquely
identifying the packet over a short time window. The number of radio
packet retries may be configurable using the radio configuration command.
Allowing more retries may increase the probability of a packet being
exchanged but introduces more latency for a round trip messages. The
default number of radio retries at power up may be ten (i.e., the maximum
transmission attempts before dropping the message).
[0838] A one byte (modulo 256) radio sequence number may be included in
all radio data packets over the RF link. Since the radio may be
responsible for retrying data packet transmission if not acknowledged,
the sequence number may provide a way for the two radios to know if a
data packet is a duplicate. The transmitted sequence number may be
incremented for each new radio data packet and may be allowed to
rollover. When a data packet is successfully received with the same
sequence number as the previous successfully received data packet (and in
the same direction), the data packet may be ACK'd and the received data
packet discarded. This may remove duplicate packets generated by the RF
protocol before they are introduced into the network. Note that it may be
possible that multiple data packets in a row may need to be dropped with
the same sequence number under extreme situations.
[0839] If a heartbeat is missed, the radio of remote control assembly 300
and the radio of infusion pump assembly 100, 100', 400, 500 may attempt
to send and listen respectively for subsequent heartbeats. The radio of
remote control assembly 300 and the radio of infusion pump assembly 100,
100', 400, 500 may automatically change from fast heartbeat mode or slow
heartbeat mode to search sync mode if heartbeats are missed for two
seconds. This may minimize power consumption when the link is lost by
allowing the radios to continue to use their synchronization information,
as two seconds allows sufficient time to hop through all channels.
[0840] The radio may be considered online while in the following modes:
[0841] Fast Heartbeat mode [0842] Slow Heartbeat mode
[0843] as these are the only conditions where messaging system traffic may
be exchanged. All other conditions may be considered offline.
[0844] The radio may initialize to radio off mode at the start of code
execution from reset. When code first executes on the radio processor,
the initial state may be the radio off mode to allow other processors to
perform self-tests before requesting the radio to be active. This
requirement does not intend to define the mode when waking from sleep
mode. The radio may cease RF communications when set to radio off mode.
On remote control assembly 300, this mode may be intended for use on an
airplane to suppress RF emissions. Since infusion pump assembly 100,
100', 400, 500 only responds to transmissions from remote control
assembly 300 (which will have ceased transmitting in airplane mode),
radio off mode may only be used on infusion pump assembly 100, 100', 400,
500 when charging.
[0845] Command processor 1802 may be informed of airplane mode and that,
therefore, the RF was intentionally turned off on remote control assembly
300 so that it does not generate walk-away alerts. However, this may be
completely hidden from the radio of infusion pump assembly 100, 100',
400, 500.
[0846] The radio of remote control assembly 300 and the radio of infusion
pump assembly 100, 100', 400, 500 may periodically attempt to exchange
heartbeats in order to reestablish data bandwidth while in search sync
mode. The radio of remote control assembly 300 may transition to radio
off mode after twenty minutes of search sync mode with no heartbeats
successfully exchanged.
[0847] The radio of infusion pump assembly 100, 100', 400, 500 may
transition to acquisition mode after twenty minutes of search sync mode
with no heartbeats successfully exchanged. Listening during pre-agreed
time slots may be the most efficient use of power for infusion pump
assembly 100, 100', 400, 500 to re-establish the RF link. After a loss of
communications, the crystal tolerance and temperature drift may make it
necessary to expand the receive window of infusion pump assembly 100,
100', 400, 500 over time. Staying in search sync mode for extended
periods (e.g., 5-20 minutes) after communications loss may cause the
instantaneous power consumed to exceed the average power budgeted for the
radio of infusion pump assembly 100, 100', 400, 500. The radio of remote
control assembly 300 may not be forced to expand its window, so staying
in search sync mode may be very power efficient. Acquisition mode may
consume more power for remote control assembly 300. Twenty minutes may be
used as a compromise to balance power consumption on both the radio of
remote control assembly 300 and the radio of infusion pump assembly 100,
100', 400, 500.
[0848] The radio of remote control assembly 300 and the radio of infusion
pump assembly 100, 100', 400, 500 may transition to slow heartbeat mode
if they successfully exchange three of the last five heartbeats.
Approximately every six seconds, a burst of five heartbeats may be
attempted. If three of these are successful, the bandwidth may be assumed
to be sufficient to transition to slow heartbeat mode. The radio of
infusion pump assembly 100, 100', 400, 500 may be acquirable while in
search sync mode with a latency of 6.1 seconds. This may imply that the
infusion pump assembly 100, 100', 400, 500 may always be listening at
least every .about.6 seconds when in search sync mode.
[0849] Radio protocol performance statistics may be necessary to promote
troubleshooting of the radio and to assess radio performance. The
following radio performance statistics may be maintained by the radio
protocol in a data structure:
TABLE-US-00012
NAME SIZE DESCRIPTION
TX Heartbeat Count 32 Bits Total transmitted heartbeats
RX Heartbeat Count 32 bits Total valid received heartbeats
CRC Errors 16 bits Total packets received over the RF link which were
dropped
due to bad CRC. This may be a subset of RX Packets
Nacked.
First Retry Count 32 bits Total number of packets which were successfully
acknowledged after 1 retry
Second Retry Count 32 bits Total number of packets which were successfully
acknowledged after 2 retries
Third Retry Count 32 bits Total number of packets which were successfully
acknowledged after 3 retries
Fourth Retry Count 32 bits Total number of packets which were successfully
acknowledged after 4 retries
Fifth Retry Count 16 bits Total number of packets which were successfully
acknowledged after 5 retries
Sixth Retry Count 16 bits Total number of packets which were successfully
acknowledged after 6 retries
Seventh Retry Count 16 bits Total number of packets which were
successfully
acknowledged after 7 retries
Eighth Retry Count 16 bits Total number of packets which were successfully
acknowledged after 8 retries
Ninth Retry Count 16 bits Total number of packets which were successfully
acknowledged after 9 retries
Tenth Retry Count 16 bits Total number of packets which were successfully
acknowledged after 10 retries
Dropped Retry Count 16 bits Total number of packets which were dropped
after
maximum retries attempts
Duplicate Packet Count 16 bits Total number of received packets dropped
due to duplicate
packet
1 to 5 Missed Fast Mode Hops 16 bits Count of 1 to 5 consecutive missed
hops in Fast mode (i.e.
not received)
6 to 16 Missed Fast Mode Hops 16 bits Count of 6 to 16 consecutive missed
hops in Fast mode.
17 to 33 Missed Fast Mode Hops 16 bits Count of 17 to 33 consecutive
missed hops in Fast mode
34+ Missed Fast Mode Hops 16 bits Count of 34 or more consecutive missed
hops in Fast mode
1 to 2 Missed Slow Mode Hops 16 bits Count of 1 to 2 consecutive missed
hops in Slow mode (i.e.
not received)
3 to 5 Missed Slow Mode Hops 16 bits Count of 3 to 5 consecutive missed
hops in Slow mode
5 to 7 Missed Slow Mode Hops 16 bits Count of 5 to 7 consecutive missed
hops in Slow mode
8+ Missed Slow Mode Hops 16 bits Count of 8 or more consecutive missed
hops in Slow mode
Destination Radio Serial Number 16 bits Count of received packets in which
the destination made it
Mismatch past the hardware filtering but does not match this radio's
serial number. This may be not an error but indicates that
the radio may be waking up and receiving (but not
processing) packets intended for other radios
Total Walkaway Time (minutes) 16 bits
Total Walkaway Events 16 bits Together with total walkaway time provides
an average
walkaway time
Number of Pairing Attempts 16 bits
Total Time in Acquisition Mode 16 bits
(Infusion pump assembly 100, 100',
400, 500 Only)
Total Acquisition Mode Attempts 16 bits Successful Acquisition Count 16
bits Count of transitions
(Remote control assembly 300 Only) from Connect or Acquisition Mode to
Fast Heartbeat Mode
Requested Slow Heartbeat Mode 16 bits
Transitions
Automatic Slow Heartbeat Mode 16 bits
Transitions
Radio offline messages sent 16 bits
Radio online messages sent 16 bits
[0850] A #define DEBUG option (compiler option) may be used to gather the
following additional radio performance statistics per each channel (16
bit numbers): [0851] Number of missed hops [0852] CCA good count [0853]
CCA bad count [0854] Average RSSI (accumulated for good RX packets only)
[0855] Dropped from Frequency Hop List count [0856] Acquisition Mode
count (found pair on this channel)
[0857] The debug option may be used to gather engineering only statistics.
If processor performance, power, and memory allow, it may be desirable to
keep this information at runtime. The radio statistics may be made
available to the messaging system.
[0858] Link quality may be intended to be used on remote control assembly
300 to provide a bar indicator, similar to a cell phone, of the radio
link quality. Link quality may be made available to both remote control
assembly 300 and infusion pump assembly 100, 100', 400, 500. It may be
anticipated that the link quality status will consist of a one byte
indicator of the quality of the radio link.
[0859] The radio may change frequency for each heartbeat. An adaptive
pseudo random frequency hopping algorithm may be used for sync mode and
heartbeat attempts in search sync mode. It may be a goal to use
sixty-four channels for frequency hopping. An algorithm may be developed
to adaptively generate a channel list on remote control assembly 300 for
frequency hopping. The radio of remote control assembly 300 may build,
maintain, and distribute the master channel list. Prior channel
statistics and historical performance information may be obtained from
the radio of infusion pump assembly 100, 100', 400, 500 by the radio of
remote control assembly 300 using the messaging system as needed to meet
performance requirements. By building the channel list from the
perspective of both units, the radio interference environment of both
units may be considered. The radios may adaptively select hopping
channels to meet the round trip message latency, while operating in a
desirable RF environment.
[0860] Occlusions and/or leaks may occur anywhere along the fluid delivery
path of infusion pump assembly 100. For example and referring to FIG.
121, occlusions/leaks may occur: in the fluid path between reservoir 118
and reservoir valve assembly 614; in the fluid path between reservoir
valve assembly 614 and pump assembly 106; in the fluid path between pump
assembly 106 and volume sensor valve assembly 612; in the fluid path
between volume sensor valve assembly 612 and volume sensor chamber 620;
in the fluid path between volume sensor chamber 620 and measurement valve
assembly 610; and in the fluid path between measurement valve assembly
610 and the tip of disposable cannula 138. Infusion pump assembly 100 may
be configured to execute one or more occlusion/leak detection algorithms
that detect and locate such occlusions/leaks and enhance the
safety/reliability of infusion pump assembly 100.
[0861] As discussed above, when administering the infusible fluid,
infusion pump assembly 100 may first determine the volume of infusible
fluid within volume sensor chamber 620 prior to the administration of the
dose of infusible fluid and may subsequently determine the volume of
infusible fluid within volume sensor chamber 620 after the administration
of the dose of infusible fluid. By monitoring these values, the
occurrence of occlusions/leaks may be detected.
[0862] Occlusion Type--Total:
[0863] When a total occlusion is occurring, the difference between the
initial measurement prior to the administration of the dose of infusible
fluid and the final measurement after the administration of the dose of
infusible fluid will be zero (or essentially zero), indicating a large
residual quantity of infusible fluid within volume sensor chamber 620.
Accordingly, no fluid may be leaving volume sensor chamber 620.
[0864] Specifically, if the tip of disposable cannula is occluded, the
fluid path down stream of volume sensor chamber 620 will fill with fluid
and eventually become pressurized to a level equivalent to the mechanical
pressure exerted by spring diaphragm 628. Accordingly, upon measurement
valve assembly 610 opening, zero (or essentially zero) fluid will be
dispensed and, therefore, the value of the initial and final measurements
(as made by volume sensor assembly 148) will essentially be equal.
[0865] Upon detecting the occurrence of such a condition, a total
occlusion indicator may be set and infusion pump assembly 100 may e.g.,
trigger an alarm, thus indicating that the user needs to seek alternative
means for receiving their therapy.
[0866] Occlusion Type--Partial:
[0867] When a partial occlusion is occurring, the difference between the
initial measurement prior to the administration of the dose of infusible
fluid and the final measurement after the administration of the dose of
infusible fluid will indicate that less than a complete dose of infusible
fluid was delivered. For example, assume that at the end of a particular
pumping cycle, volume sensor assembly 148 indicated that 0.10 microliters
of infusible fluid were present in volume sensor chamber 620. Further,
assume that measurement value assembly 610 is subsequently closed and
pump assembly 106 is subsequently actuated, resulting in volume sensor
chamber 620 being filed with the infusible fluid. Further assume that
volume sensor assembly 148 determines that volume sensor chamber 620 is
now filled with 1.00 microliters of infusible fluid (indicating a pumped
volume of 0.90 microliters).
[0868] Accordingly, upon the opening of measurement valve assembly 610,
the quantity of infusible fluid included within volume sensor chamber
would be expected to drop to 0.10 microliters (or reasonably close
thereto). However, in the event of a partial occlusion, due to a
slower-than-normal flow rate from volume sensor chamber 620, the quantity
of infusible fluid within volume sensor chamber 620 may only be reduced
to 0.40 microliters (indicating a delivered volume of 0.60 microliters).
Accordingly, by monitoring the difference between the pumped volume (0.90
microliters) and the delivered volume (0.60 microliters), the residual
volume may be defined and the occurrence of a partial occlusion may be
detected.
[0869] Upon detecting the occurrence of such a condition, a partial
occlusion indicator may be set and infusion pump assembly 100 may e.g.,
trigger an alarm, thus indicating that the user needs to seek alternative
means for receiving their therapy. However, as this is indicative of a
partial occlusion (as opposed to a complete occlusion), the issuance of
an alarm may be delayed, as the partial occlusion may clear itself.
[0870] Alternatively, infusion pump assembly 100 may: calculate a pump
ontime to volume delivered ratio; track it through time; and track by
using a fast moving and a slow moving exponential average of the pump
ontime. The exponential average may be tracked, in a fashion similar to
the leaky sum integrator. The infusion pump assembly 100 may filter
signal and look for a fast change. The rate of fluid outflow and/or
residual volume may be monitored. If the residual volume does not change,
then there may be a total occlusion. If the residual volume changed, they
may be a partial occlusion. Alternatively still, the residual values may
be summed. If the number of valve actuations or the latch time is being
varied, the fluid flow rate may be examined, even if you build up
pressure in volume sensor assembly 148.
[0871] Total/Partial Empty Reservoir:
[0872] When reservoir 118 is becoming empty, it will become more difficult
to fill volume sensor chamber 620 to the desired level. Typically, pump
assembly 106 is capable of pumping 1.0 microliters per millisecond. For
example, assume that an "empty" condition for volume sensor chamber 620
is 0.10 microliters and a "full" condition for volume sensor chamber 620
is 1.00 microliters. However, as reservoir 118 begins to empty, it may
become harder for pump assembly 106 to fill volume sensor chamber 620 to
the "full" condition and may consistently miss the goal. Accordingly,
during normal operations, it may take one second for pump assembly 106 to
fill volume sensor chamber 620 to the "full" condition and, as reservoir
118 empties, it may take three seconds to fill volume sensor chamber 620
to the "full" condition. Eventually, if reservoir 118 completely empties,
volume sensor chamber 620 may never be able to achieve a "full
condition". Accordingly, the inability of pump assembly 106 to fill
volume sensor chamber 620 to a "full" condition may be indicative of
reservoir 118 being empty. Alternatively, the occurrence of such a
condition may be indicative of other situations (e.g., the failure of
pump assembly 106 or an occlusion in the fluid path prior to volume
sensor chamber 620). Infusion pump assembly 100 may determine the
difference between the "full" condition and the amount actually pumped.
These differences may be summed and the made up for once the reservoir
condition is addressed.
[0873] Upon detecting the occurrence of such a condition, an empty
indicator may be set and infusion pump assembly 100 may e.g., trigger an
alarm, thus indicating that the user needs to e.g., replace disposable
housing assembly 114.
[0874] Additionally, as reservoir 118 empties, reservoir 118 will
eventually result in a "vacuum" condition and the ability of pump
assembly 106 to deliver fluid to volume sensor chamber 620 may be
compromised. As discussed above, volume controller 1602 may include feed
forward controller 1652 for setting an initial "guess" concerning
"on-time" signal 1606, wherein this initial guess is based upon a pump
calibration curve. For example, in order for pump assembly 106 to deliver
0.010 units of infusible fluid, feed forward controller 1652 may define
an initial "on-time" of e.g., one millisecond. However, as reservoir 118
begins to empty, due to compromised pumping conditions, it may take two
milliseconds to deliver 0.010 units of infusible fluid. Further, as
reservoir 118 approaches a fully empty condition, it make take ten
milliseconds to deliver 0.010 units of infusible fluid. Accordingly, the
occurrence of reservoir 118 approaching an empty condition may be
detected by monitoring the level at which the actual operation of pump
assembly 106 (e.g., two milliseconds to deliver 0.010 units of infusible
fluid) differs from the anticipated operation of pump assembly 106 (e.g.,
one millisecond to deliver 0.010 units of infusible fluid).
[0875] Upon detecting the occurrence of such a condition, a reserve
indicator may be set and infusion pump assembly 100 may e.g., trigger an
alarm, thus indicating that the user will need to e.g., replace
disposable housing assembly 114 shortly.
[0876] Leak Detection:
[0877] In the event of a leak (e.g., a leaky valve or a
rupture/perforation) within the fluid path, the ability of the fluid path
to retain fluid pressure may be compromised. Accordingly, in order to
check for leaks within the fluid path, a bleed down test may be performed
in which pump assembly 106 is used to pressurize volume sensor chamber
620. Volume sensor assembly 148 may then perform a first volume
measurement (as described above) to determine the volume of infusible
fluid within volume sensor chamber 620. Infusion pump assembly 100 may
then wait a defined period of time to allow for bleed down in the event
of a leak. For example, after a sixty second bleed down period, volume
sensor assembly 148 may perform a second volume measurement (as described
above) to determine the volume of infusible fluid within volume sensor
chamber 620. If there are no leaks, the two volume measurements should be
essentially the same. However, in the event of a leak, the second
measurement may be less then the first measurement. Additionally,
depending on the severity of the leak, pump assembly 106 may be incapable
of filling volume sensor chamber 620. Typically, a leak check may be
performed as part of a delivery of infusible fluid.
[0878] In the event that the difference between the first volume
measurement and the second volume measurement exceeds an acceptable
threshold, a leak indicator may be set and infusion pump assembly 100 may
e.g., trigger an alarm, thus indicating that the user needs to seek
alternative means for receiving their therapy
[0879] As discussed above, infusion pump assembly 100 may include
supervisor processor 1800, command processor 1802, and radio processor
1818. Unfortunately, once assembled, access to electrical control
assembly 110 within infusion pump assembly 100 very limited. Accordingly,
the only means to access electrical control assembly 110 (e.g., for
upgrading flash memories) may be through the communication channel
established between infusion pump assembly 100, 100', 400, 500 and remote
control assembly 300, or via electrical contacts 834 used by battery
charger 1200.
[0880] Electrical contacts 834 may be directly coupled to radio processor
1818 and may be configured to provide I2C communication capability for
erasing/programming any flash memory (not shown) included within radio
processor 1818. The process of loading a program into radio processor
1818 may provide a means for erasing/programming of the flash memories in
both the supervisor processor 1800 and command processor 1802.
[0881] When programming supervisor processor 1800 or command processor
1802, the program (i.e., data) to be loaded into flash memory accessible
by supervisor processor 1800 or command processor 1802 may be provided in
a plurality of data blocks. This is because the radio processor 1818 may
not have enough memory to hold the entire flash image of the software as
one block.
[0882] Referring also to FIG. 122, there is shown one illustrative example
of the manner in which the various systems within infusion pump assembly
100, 100', 400, 500 may be interconnected. For example, battery charger
1200 may be coupled to computing device 2100 (e.g., a personal computer)
via bus translator 2102, which converts e.g., RS232 formatted data to
e.g., I2C formatted data. Bus translator 2102 may execute a pass-through
program that effectuates the above-described translation. Battery charger
1200 may be coupled to radio processor 181 via electrical contacts 834
(described above). Radio processor 1818 may then be coupled to supervisor
processor 1800 and command processor 1802 via e.g., an RS232 bus. Radio
processor 1818 may execute an update program that allows radio processor
1818 to control/orchestrate the updating of the flash memories accessible
by supervisor processor 1800 and command processor 1802. Accordingly,
through the use of the above-described coupling, software updates
obtained by computing device 2100 may be uploaded to flash memory (not
shown) accessible by supervisor processor 1800 and command processor
1802. The above-described software updates may be command line program
that may be automatically invoked by a script process.
[0883] As discussed above, infusion pump assembly 100, 100' 400, 500 may
be configured to deliver an infusible fluid to a user. Further and as
discussed above, infusion pump assembly 100, 100' 400, 500 may deliver
the infusible fluid via sequential, multi-part, infusion events (that may
include a plurality of discrete infusion events) and/or one-time infusion
events. However, in some embodiments, infusion pump assembly 100, 100'
400, 500 may deliver stacking bolus infusion events. For example, a user
may request the delivery of a bolus, e.g., 6 units. While the 6 units are
in the process of being delivered to the user, the user may request a
second bolus, e.g., 3 units. In some embodiments of infusion pump
assembly 100, 100' 400, 500 may deliver the second bolus at the
completion of the first bolus.
[0884] Examples of other such sequential, multi-part, infusion events may
include but are not limited to a basal infusion event and an
extended-bolus infusion event. As is known in the art, a basal infusion
event refers to the repeated injection of small (e.g. 0.05 unit)
quantities of infusible fluid at a predefined interval (e.g. every three
minutes) that may be repeated until stopped, e.g., by a user or by the
system. Further, the basal infusion rates may be pre-programmed and may
include specified rates for pre-programmed time-frames, e.g., a rate of
0.50 units per hour from 6:00 am-3:00 pm; a rate of 0.40 units per hour
from 3:00 pm-10:00 pm; and a rate of 0.35 units per hour from 10:00
pm-6:00 am. However, the basal rate may be 0.025 units per hour, and may
not change according to pre-programmed time-frames. The basal rates may
be repeated regularly/daily until otherwise changed.
[0885] Further and as is known in the art, an extended-bolus infusion
event may refer to the repeated injection of small (e.g. 0.05 unit)
quantities of infusible fluid at a predefined interval (e.g. every three
minutes) that is repeated for a defined number of intervals (e.g., three
intervals) or for a defined period of time (e.g., nine minutes). An
extended-bolus infusion event may occur simultaneously with a basal
infusion event.
[0886] If multiple infusion events conflict with each other, infusion pump
assembly 100, 100' 400, 500 may prioritize the infusion event in the
follow manner.
[0887] Referring also to FIG. 123, assume for illustrative purposes only
that the user configures infusion pump assembly 100, 100' 400, 500 to
administer a basal dose (e.g. 0.05 units) of infusible fluid every three
minutes. The user may utilize remote control assembly 300 to define a
basal infusion event for the infusible fluid (e.g., 1.00 units per hour).
[0888] Infusion pump assembly 100, 100' 400, 500 may then determine an
infusion schedule based upon the basal infusion event defined. Once
determined, infusion pump assembly 100, 100' 400, 500 may administer the
sequential, multi-part, infusion event (e.g., 0.05 units of infusible
fluid every three minutes). Accordingly, while administering the
sequential, multi-part, infusion event, infusion pump assembly 100, 100'
400, 500: may infuse a first 0.05 unit dose 2200 of the infusible fluid
at t=0:00 (i.e., a first discrete infusion event), may infuse a second
0.05 unit dose 2202 of the infusible fluid at t=3:00 (i.e., a second
discrete infusion event); may infuse a third 0.05 unit dose 2204 of the
infusible fluid at t=6:00 (i.e., a third discrete infusion event); may
infuse a fourth 0.05 unit dose 2206 of the infusible fluid at t=9:00
(i.e., a fourth discrete infusion event); and may infuse a fifth 0.05
unit dose 2208 of the infusible fluid at t=12:00 (i.e., a fifth discrete
infusion event). As discussed above, this pattern of infusing 0.05 unit
doses of the infusible fluid every three minutes may be repeated until
stopped, e.g., by a user or by the system, in this example, as this is an
illustrative example of a basal infusion event.
[0889] Further, assume for illustrative purposes that the infusible fluid
is insulin and sometime after the first 0.05 unit dose 2200 of infusible
fluid is administered (but before the second 0.05 unit dose 2202 of
infusible fluid is administered), the user checks their blood glucose
level and realizes that their blood glucose level is running a little
higher than normal. Accordingly, the user may define an extended bolus
infusion event via remote control assembly 300. An extended bolus
infusion event may refer to the continuous infusion of a defined quantity
of infusible fluid over a finite period of time. However, as such an
infusion methodology is impractical/undesirable for an infusion pump
assembly, when administered by such an infusion pump assembly, an
extended bolus infusion event may refer to the infusion of additional
small doses of infusible fluid over a finite period of time.
[0890] Accordingly, the user may utilize remote control assembly 300 to
define an extended bolus infusion event for the infusible fluid (e.g.,
0.20 units over the next six minutes), which may be confirmed in a manner
discussed above. While, in this example, the extended bolus infusion
event is described as 0.20 units over the next six minutes, this is for
illustrative purposes only and is not intended to be a limitation of this
disclosure, as either or both of the unit quantity and total time
interval may be adjusted upward or downward. Once defined and/or
confirmed, infusion pump assembly 100, 100' 400, 500 may determine an
infusion schedule based upon the extended bolus infusion event defined;
and may administer the infusible fluid. For example, infusion pump
assembly 100, 100' 400, 500 may deliver 0.10 units of infusible fluid
every three minutes for the next two interval cycles (or six minutes),
resulting in the delivery of the extended bolus dose of infusible fluid
defined by the user (i.e., 0.20 units over the next six minutes).
[0891] Accordingly, while administering the second, sequential,
multi-part, infusion event, infusion pump assembly 100, 100' 400, 500 may
infuse a first 0.10 unit dose 2210 of the infusible fluid at t=3:00
(e.g., after administering the second 0.05 unit dose 2202 of infusible
fluid). Infusion pump assembly 100, 100' 400, 500 may also infuse a
second 0.10 unit dose 2212 of the infusible fluid at t=6:00 (e.g., after
administering the third 0.05 unit dose 2204 of infusible fluid).
[0892] Assume for illustrative purposes only that after the user programs
infusion pump assembly 100, 100' 400, 500 via remote control assembly 300
to administer the first sequential, multi-part, infusion event (i.e.,
0.05 units infused every three minute interval repeated continuously) and
administer the second sequential, multi-part, infusion event (i.e., 0.10
units infused every three minute interval for two intervals), the user
decides to eat a very large meal. Predicting that their blood glucose
level might increase considerably, the user may program infusion pump
assembly 100, 100' 400, 500 (via remote control assembly 300) to
administer a one-time infusion event. An example of such a one-time
infusion event may include but is not limited to a normal bolus infusion
event. As is known in the art, a normal bolus infusion event refers to a
one-time infusion of the infusible fluid.
[0893] For illustrative purposes only, assume that the user wishes to have
infusion pump assembly 100, 100' 400, 500 administer a bolus dose of
thirty-six units of the infusible fluid. Infusion pump assembly 100, 100'
400, 500 may monitor the various infusion events being administered to
determine whether a one-time infusion event is available to be
administered. If a one-time infusion event is available for
administration, infusion pump assembly 100, 100' 400, 500 may delay the
administration of at least a portion of the sequential, multi-part,
infusion event.
[0894] Continuing with the above-stated example, once the user completes
the programming of infusion pump assembly 100, 100' 400, 500 to deliver
one-time infusion event 2214 (i.e., the thirty-six unit bolus dose of the
infusible fluid), upon infusion pump assembly 100, 100' 400, 500
determining that the one-time infusion event is available for
administration, infusion pump assembly 100, 100' 400, 500 may delay the
administration of each sequential, multi-part infusion event and
administer the available one-time infusion event.
[0895] Specifically and as discussed above, prior to the user programming
infusion pump assembly 100, 100' 400, 500 to deliver one-time infusion
event 2214, infusion pump assembly 100, 100' 400, 500 was administering a
first sequential, multi-part, infusion event (i.e., 0.05 units infused
every three minute interval repeated continuously) and administering a
second sequential, multi-part, infusion event (i.e., 0.10 units infused
every three minute interval for two intervals).
[0896] For illustrative purposes only, the first sequential, multi-part,
infusion event may be represented within FIG. 123 as 0.05 unit dose 2200
@ t=0:00, 0.05 unit dose 2202 @ t=3:00, 0.05 unit dose 2204 @ t=6:00,
0.05 unit dose 2206 @ t=9:00, and 0.05 unit dose 2208 @ t=12:00. As the
first sequential, multi-part, infusion event as described above is a
basal infusion event, infusion pump assembly 100, 100' 400, 500 may
continue to infuse 0.05 unit doses of the infusible fluid at three minute
intervals indefinitely (i.e., until the procedure is cancelled by the
user).
[0897] Further and for illustrative purposes only, the second sequential,
multi-part, infusion event may be represented within FIG. 123 as 0.10
unit dose 2210 @ t=3:00 and 0.10 unit dose 2212 @ t=6:00. As the second
sequential, multi-part, infusion event is described above as an extended
bolus infusion event, infusion pump assembly 100, 100' 400, 500 may
continue to infuse 0.10 unit doses of the infusible fluid at three minute
intervals for exactly two intervals (i.e., the number of intervals
defined by the user).
[0898] Continuing with the above-stated example, upon infusion pump
assembly 100, 100' 400, 500 determining that the thirty-six unit normal
bolus dose of the infusible fluid (i.e., one-time infusion event 2214) is
available for administration, infusion pump assembly 100, 100' 400, 500
may delay the administration of each sequential, multi-part infusion
event and may start administering one-time infusion event 2214 that is
available for administration.
[0899] Accordingly and for illustrative purposes only, assume that upon
completion of the programming of infusion pump assembly 100, 100' 400,
500 to deliver the thirty-six unit normal bolus does of the infusible
fluid (i.e., the one-time infusion event), infusion pump assembly 100,
100' 400, 500 begins administering one-time infusion event 2214. Being
that one-time infusion event 2214 is comparatively large, it may take
longer than three minutes (i.e., the time interval between individual
infused doses of the sequential, multi-part, infusion events) and one or
more of the individual infused doses of the sequential, multi-part,
infusion events may need to be delayed.
[0900] Specifically, assume that it will take infusion pump assembly 100,
100' 400, 500 greater than six minutes to infuse thirty-six units of the
infusible fluid. Accordingly, infusion pump assembly 100, 100' 400, 500
may delay 0.05 unit dose 2202 (i.e., scheduled to be infused @ t=3:00),
0.05 unit dose 2204 (i.e., scheduled to be infused @ t=6:00), and 0.05
unit dose 2206 (i.e., scheduled to be infused @ t=9:00) until after
one-time infusion event 2214 (i.e., the thirty-six unit normal bolus dose
of the infusible fluid) is completely administered. Further, infusion
pump assembly 100, 100' 400, 500 may delay 0.10 unit dose 2210 (i.e.,
scheduled to be infused @ t=3:00 and 0.10 unit dose 2212 (i.e., scheduled
to be infused @ t=6:00) until after one-time infusion event 2214.
[0901] Once administration of one-time infusion event 2214 is completed by
infusion pump assembly 100, 100' 400, 500, any discrete infusion events
included within the sequential, multi-part, infusion event that were
delayed may be administered by infusion pump assembly 100, 100' 400, 500.
Accordingly, once one-time infusion event 2214 (i.e., the thirty-six unit
normal bolus dose of the infusible fluid) is completely administered,
infusion pump assembly 100, 100' 400, 500 may administer 0.05 unit dose
2202, 0.05 unit dose 2204, 0.05 unit dose 2206, 0.10 unit dose 2210, and
0.10 unit dose 2212.
[0902] While infusion pump assembly 100, 100' 400, 500 is shown to
administer 0.05 unit dose 2202, then 0.10 unit dose 2210, then 0.05 unit
dose 2204, then 0.10 unit dose 2212, and then 0.05 unit dose 2206, this
is for illustrative purposes only and is not intended to be a limitation
of this disclosure, as other configurations are possible and are
considered to be within the scope of this disclosure. For example, upon
infusion pump assembly 100, 100' 400, 500 completing the administration
of one-time infusion event 2214 (i.e., the thirty-six unit normal bolus
dose of the infusible fluid), infusion pump assembly 100, 100' 400, 500
may administer all of the delayed discrete infusion events associated
with the first sequential, multi-part infusion event (i.e., namely 0.05
unit dose 2202, 0.05 unit dose 2204, and 0.05 unit dose 2206). Infusion
pump assembly 100, 100' 400, 500 may then administer all of the delayed
discrete infusion events associated with the second sequential,
multi-part infusion event (i.e., 0.10 unit dose 2210, and 0.10 unit dose
2212).
[0903] While one-time infusion event 2214 (i.e., the thirty-six unit
normal bolus dose of the infusible fluid) is shown as being infused
beginning at t=3:00, this is for illustrative purposes only and is not
intended to be a limitation of this disclosure. Specifically, infusion
pump assembly 100, 100' 400, 500 may not need to begin infusing one-time
infusion event 2214 at one of the three-minute intervals (e.g., t=0:00,
t=3:00, t=6:00, t=9:00, or t=12:00) and may begin administering one-time
infusion event 2214 at any time.
[0904] While each discrete infusion event (e.g., 0.05 unit dose 2202, 0.05
unit dose 2204, 0.05 unit dose 2206, 0.10 unit dose 2210, and 0.10 unit
dose 2212) and one-time infusion event 2214 are shown as being a single
event, this is for illustrative purposes only and is not intended to be a
limitation of this disclosure. Specifically, at least one of the
plurality of discrete infusion events e.g., 0.05 unit dose 2202, 0.05
unit dose 2204, 0.05 unit dose 2206, 0.10 unit dose 2210, and 0.10 unit
dose 2212) may include a plurality of discrete infusion sub-events.
Further, one-time infusion event 2214 may include a plurality of one-time
infusion sub-events.
[0905] Referring also to FIG. 124 and for illustrative purposes, 0.05 unit
dose 2202 is shown to include ten discrete infusion sub-events (e.g.,
infusion sub-events 2216.sub.1-10), wherein a 0.005 unit dose of the
infusible fluid is infused during each of the ten discrete infusion
sub-events. Additionally, 0.10 unit dose 2210 is shown to include ten
discrete infusion sub-events (e.g., infusion sub-events 2218.sub.1-10),
wherein a 0.01 unit dose of the infusible fluid is delivered during each
of the ten discrete infusion sub-events. Further, one-time infusion event
2214 may include e.g., three-hundred-sixty one-time infusion sub-events
(not shown), wherein a 0.1 unit dose of the infusible fluid is delivered
during each of the three-hundred-sixty one-time infusion sub-events. The
number of sub-events defined above and the quantity of the infusible
fluid delivered during each sub-event is solely for illustrative purposes
only and is not intended to be a limitation of this disclosure, as the
number of sub-events and/or the quantity of the infusible fluid delivered
during each sub-event may be increased or decreased depending upon e.g.,
the design criteria of infusion pump assembly 100, 100' 400, 500.
[0906] Before, after, or in between the above-described infusion
sub-events, infusion pump assembly 100, 100' 400, 500 may confirm the
proper operation of infusion pump assembly 100, 100' 400, 500 through the
use of any of the above-described safety features (e.g., occlusion
detection methodologies and/or failure detection methodologies).
[0907] In the exemplary embodiments, the infusion pump assembly may be
wirelessly controlled by a remote control device. In the exemplary
embodiments, a split ring resonator antenna may be used for wireless
communication between the infusion pump assembly and the remote control
device (or other remote device). The term "wirelessly controlled" refers
to any device that may receive input, instructions, data, or other,
wirelessly. Further, a wirelessly controlled insulin pump refers to any
insulin pump that may wirelessly transmit and/or receive data from
another device. Thus, for example, an insulin pump may both receive
instructions via direct input by a user and may receive instructions
wirelessly from a remote controller.
[0908] Referring to FIG. 127 and FIG. 131, an exemplary embodiment of a
split ring resonator antenna adapted for use in a wirelessly controlled
medical device, and is used in the exemplary embodiment of the infusion
pump assembly, includes at least one split ring resonator antenna
(hereinafter "SRR antenna") 2508, a wearable electric circuit, such as a
wirelessly controlled medical infusion apparatus (hereinafter "infusion
apparatus") 2514, capable of powering the antenna, and a control unit
2522.
[0909] In various embodiments, a SRR antenna 2508 may reside on the
surface of a non-conducting substrate base 2500, allowing a metallic
layer (or layers) to resonate at a predetermined frequency. The substrate
base 2500 may be composed of standard printed circuit board material such
as Flame Retardant 2 (FR-2), FR-3, FR-4, FR-5, FR-6, G-10, CEM-1, CEM-2,
CEM-3, CEM-4, CEM-5, Polyimide, Teflon, ceramics, or flexible Mylar. The
metallic resonating bodies comprising a SRR antenna 2508 may be made of
two rectangular metallic layers 2502, 2504, made of, for example,
platinum, iridium, copper, nickel, stainless steel, silver or other
conducting materials. In other various embodiments, a SRR antenna 2508
may contain only one metallic resonating body.
[0910] In the exemplary embodiment, a gold-plated copper outer layer 2502,
surrounds, without physically contacting, a gold-plated copper inner ring
2504. That is, the inner ring 2504 resides in the cavity 2510 (or
aperture) formed by the outer layer 2502. The inner ring 2504 may contain
a gap, or split 2506, along its surface completely severing the material
to form an incomplete ring shape. Both metallic resonating bodies 2502,
2504 may reside on the same planar surface of the substrate base 2500. In
such a configuration, the outer layer 2502 may by driven via a
transmission line 2512 coupled to the outer layer 2502, for example.
Additionally, in various other embodiments, a transmission line 2512 may
be coupled to the inner ring 2504.
[0911] Antenna design software, such as AWR Microwave Office, capable of
simulating electromagnetic geometries, such as, antenna performance, may
significantly decrease the time required to produce satisfactory
dimensions compared to physically fabricating and testing antennas.
Accordingly, with aid of such software, the SRR antenna 2508 may be
designed such that the geometric dimensions of the resonant bodies 2502,
2504 facilitate an operational frequency of 2.4 GHz. FIG. 132 depicts the
exemplary dimensions of the inner ring 2504 and outer layer 2502, and the
positioning of the cavity 2510 in which the inner ring 2504 resides. The
distance in between the outer layer 2502 and the inner ring 2504 is a
constant 0.005 inches along the perimeter of the cavity 2510. However, in
other embodiments, the distance between the outer layer and the inner
ring may vary and in some embodiments, the operational frequency may
vary.
[0912] In various embodiments, a SRR antenna 2508 may have dimensions such
that it could be categorized as electrically small, that is, the greatest
dimension of the antenna being far less than one wavelength at
operational frequency.
[0913] In various other embodiments, a SRR antenna 2508 may be composed of
one or more alternatively-shaped metallic outer layers, such as circular,
pentagonal, octagonal, or hexagonal, surrounding one or more metallic
inner layers of similar shape. Further, in various other embodiments, one
or more metallic layers of a SRR antenna 2508 may contain gaps in the
material, forming incomplete shapes.
[0914] Referring to FIG. 130, a SRR antenna 2508 having the exemplary
geometry exhibits acceptable return loss and frequency values when placed
in contact with human skin. As shown in FIG. 130, focusing on the band of
interest denoted by markers 1 and 2 on the graph, return loss prior to
contact with human skin is near -15 dB while monitoring a frequency band
centered around 2.44 GHz. Return loss during contact with human skin, as
shown in FIG. 130A, remains a suitable value near -25 dB at the same
frequency, yielding approximately 97% transmission power.
[0915] These results are favorable especially as compared with a non-split
ring resonator antenna type, such as the Inverted-F. Return loss of an
Inverted-F antenna may exhibit a difference when the antenna contacts
human skin, resulting in a low percentage of power transmitted outward
from the antenna. By way of example, as shown in FIG. 133, and again
focusing on the band of interest denoted by markers 1 and 2 on the graph,
return loss of an Inverted-F antenna prior to contact with human skin is
near -25 dB at a frequency centered around 2.44 GHz. Return loss during
contact with human skin is nearly -2 dB at the same frequency, yielding
approximately 37% power transmission.
[0916] Integration with a Wireless Medical Device
[0917] In the exemplary embodiment, referring to FIG. 132 and FIG. 128,
one application of a SRR antenna 2508 may be integration into a wearable
infusion apparatus 2514 capable of delivering fluid medication to a
user/patient 2524. In such an application, the safety of the user/patient
is dependent on fluid operation between these electrical components, thus
reliable wireless transmission to and from a control unit 2522 is of
great importance.
[0918] An infusion apparatus 2514 may be worn directly on the human body.
By way of example, such a device may be attached on or above the hip
joint in direct contact with human skin, placing the SRR antenna 2508 at
risk of unintended dielectric loading causing a frequency shift in
electrical operation. However, in such an application, electrical
characteristics of the SRR antenna 2508 which allow it to be less
sensitive to nearby parasitic objects are beneficial in reducing or
eliminating degradation to the performance. A controlling component, such
as a control unit 2522 (generally shown in FIG. 131), may be paired with
an infusion apparatus 2514, and may be designed to transmit and receive
wireless signals to and from the infusion apparatus 2514 at a
predetermined frequency, such as 2.4 GHz. In the exemplary embodiment,
the control unit 2522 serves as the main user interface through which a
patient or third party may manage insulin delivery. In other embodiments,
infusion apparatus 2514 may utilize a SRR antenna 2508 to communicate
with one or more control units 2522.
[0919] In various embodiments, a number of different wireless
communication protocols may be used in conjunction with the SRR antenna
2508, as the protocol and data types to be transferred are independent of
the electrical characteristics of the antenna. However, in the exemplary
embodiment, a bi-directional master/slave means of communication
organizes the data transfer through the SRR antenna 2508. The control
unit 2522 may act as the master by periodically polling the infusion
apparatus 2514, or slave, for information. In the exemplary embodiment,
only when the slave is polled, the slave may send signals to the control
unit 2522 only when the slave is polled. However, in other embodiments,
the slave may send signals before being polled. Signals sent by way of
this system may include, but are not limited to, control, alarm, status,
patient treatment profile, treatment logs, channel selection and
negotiation, handshaking, encryption, and check-sum. In some embodiments,
transmission through the SRR antenna 2508 may also be halted during
certain infusion operations as an added precaution against electrical
disruption of administration of insulin to the patient.
[0920] In the exemplary embodiment, the SRR antenna 2508 may be coupled to
electrical source circuitry via one or more pins 2516 on a transmission
line 2512. In various other embodiments a transmission line may comprise
a wire, pairs of wire, or other controlled impedance methods providing a
channel by which the SRR antenna 2508 is able to resonate at a certain
frequency. The transmission line 2512 may reside on the surface of the
substrate base 2500 and may be composed of the same material as the SRR
antenna 2508, such as gold-plated copper. Additionally, a ground plane
may be attached to the surface of the substrate base opposite the
transmission line 2512.
[0921] The electrical circuitry coupled to the SRR antenna 2508 may apply
an RF signal to the end of the transmission line 2512 nearest the
circuitry, creating an electromagnetic field throughout, and propagating
from, the SRR antenna 2508. The electrical circuitry coupled to the SRR
antenna 2508 facilitates resonance at a predetermined frequency, such as
2.4 GHz. Preferably, transmission line 2512 and SRR antenna 2508 both
have impedances of 50 Ohms to simplify circuit simulation and
characterization. However, in other various embodiments, the transmission
line and split ring resonator antenna may have other impendence values,
or a different resonating frequency.
[0922] Referring to FIG. 129, a signal processing component(s) 2518, such
as, a filter, amplifier, or switch, may be integrated into the
transmission line 2512, or at some point between the signal source
connection pins 2516 and the SRR antenna 2508. In the exemplary
embodiment, the signal processing component 2518 is a band-pass filter to
facilitate desired signal processing, such as, allowing only the
exemplary frequency to be transmitted to the antenna, and rejecting
frequencies outside that range. In the exemplary embodiment, a Combline
band-pass filter 2518 may be included in the transmission line 2512
between the antenna and the signal source. However in other embodiments,
any other signal processing device, for example, but not limited to,
filters, amplifiers, or any other signal processing devices known in the
art.
[0923] In various embodiments, a SRR antenna 2508 may be composed of
metallic bodies capable of resonating on a flexible or rigid substrate.
As shown in FIG. 128 and FIG. 3, the exemplary embodiment incorporates a
curved SRR antenna on a flexible Polyimide substrate 2520. Polyimide may
be the exemplary material because it tends to be more flexible than
alternative substrates. This configuration may allow for simplified
integration into circular-shaped devices (such as a wirelessly controlled
medical infusion apparatus 2514), devices with irregular-shaped external
housing, or devices in which saving space is paramount.
[0924] In various embodiments, both control unit 2522 and base unit 2514
may incorporate a split SRR antenna 2508. This configuration may prove
beneficial where the control unit is meant to be handheld, in close
proximity to human skin, or is likely to be in close proximity to a
varying number of materials with varying dielectric constants.
[0925] In various other embodiments, a SRR antenna 2508 may be integrated
into a human or animal limb replacement. As prosthetic limbs are becoming
more sophisticated the electrical systems developed to control and
simulate muscle movements require much more wiring and data transfer
among subsystems. Wireless data transfer within a prosthetic limb may
reduce weight through reduced physical wiring, conserve space, and allow
greater freedom of movement. However, common antennas in such a system
may be susceptible to dielectric loading. Similar to the previously
mentioned benefits of integrating a SRR antenna 2508 into a wirelessly
controlled medical infusion apparatus, a prosthetic limb, such as a
robotic arm, may also come into contact with human skin or other
dielectric materials and benefit from the reduction of electrical
disturbances associated with such an antenna. In other various
embodiments, the SRR antenna 2508 may be integrated into any device
comprised of the electrical components capable of powering and
transmitting/receiving data to an antenna and susceptible to electrical
disturbances associated with proximity to dielectric materials.
[0926] In various embodiments, a SRR antenna 2508 may be integrated into a
configuration of medical components in which one or more implantable
medical devices, operating within the human body, communicate wirelessly
to a handheld, body-mounted, or remote control unit. In certain
embodiments, both body-mounted and in-body wireless devices may utilize a
SRR antenna 2508 for wireless communication. Additionally, one or more of
the components utilizing a SRR antenna 2508 may be completely surrounded
by human skin, tissue or other dielectric material. By way of example,
such a configuration may be used in conjunction with a heart
monitoring/control system where stability and consistency of wireless
data transmission are of fundamental concern.
[0927] In various other embodiments, a SRR antenna 2508 may be integrated
into the embodiments of the infusion pump assembly. Configuration of
medical components in which one or more electrical sensors positioned on,
or attached to, the human body wirelessly communicate to a remote
transceiving unit. By way of example, a plurality of electrodes
positioned on the body may be coupled to a wireless unit employing a SRR
antenna 2508 for wireless transmission to a remotely located
electrocardiogram machine. By way of further example, a wireless
temperature sensor in contact with human skin may employ SRR antenna 2508
for wireless communication to a controller unit for temperature
regulation of the room in which the sensor resides.
[0928] As discussed and described above, in some embodiments of the
infusion pump system the SMA may control both the pump assembly
(including the pump assembly 106, however, in various other embodiments,
the SMA may also control of various embodiments of the pump assembly),
and the various embodiments shown and described herein of the measurement
valve assembly. However, in some embodiments, the SMA may be controlled
using at least one optical position sensor assembly ("optical sensor")
wherein the position of the pump assembly plunger ("pump plunger") and
the measurement valve plunger is measured using at least one optical
position sensor, and in the exemplary embodiments, at least one pump
assembly plunger optical sensor and at least one measurement valve
plunger optical position sensor. Thus, in these embodiments, the command
processor provides closed-loop control of the pump plunger position and
measurement valve plunger position by comparing the optical sensor output
to a target position and then modifying the PWM of the low-side field
effect transistors ("FET"). In addition, voltages are measured at various
positions such the SMA controller may detect various conditions of the
system including, but not limited to, one or more of the following: a
broken SMA wire, failed FET and/or a depleted battery assembly and/or
power source. Thus, the actual plunger position may be determined for, in
some embodiments, both the pump plunger and the measurement valve
plunger, and target plunger positions may be established.
[0929] Referring now to FIGS. 145-149B various embodiments of the optical
position sensor in the infusion pump system is shown. Some embodiments of
the apparatus, methods and systems will be described below with reference
to an exemplary embodiment. The exemplary embodiment is described with
respect to a medical infusion pump, which in some embodiments may be an
infusion pump, which may, in some embodiments, be an insulin pump, as
shown and described herein, however, the optical position sensor
described herein may also be used with various other infusion pumps
and/or medical delivery devices and/or medical systems including, but not
limited to, those described in U.S. Pat. No. 7,498,563 issued Mar. 3,
2009 and entitled Optical Displacement Sensor for Infusion Devices
(Attorney Docket No. D78), U.S. Pat. No. 7,306,578 issued Dec. 11, 2007
and entitled Loading Mechanism for Infusion Pump (Attorney Docket No.
C54), U.S. patent application Ser. No. 11/704,899 filed Feb. 9, 2007, now
U.S. Publication No. US-2007-0228071-A1, and entitled Fluid Delivery
Systems and Methods (Attorney Docket No. E70), U.S. patent application
Ser. No. 11/704,896 filed Feb. 9, 2007, now U.S. Publication No.
US-2007-0219496-A1, published Sep. 20, 2007 and entitled Pumping Fluid
Delivery Systems and Methods Using Force Application Assembly (Attorney
Docket No. E71), U.S. patent application Ser. No. 11/704,886 filed Feb.
9, 2007, now U.S. Publication No. US-2007-0219480-A1, published Sep. 20,
2007 and entitled Patch-Sized Fluid Delivery Systems and Methods
(Attorney Docket No. E72), U.S. patent application Ser. No. 11/704,897
filed Feb. 9, 2007, now U.S. Publication No. US-2007-0219597-A1,
published Sep. 20, 2007 and entitled Adhesive and Peripheral Systems and
Methods for Medical Devices (Attorney Docket No. E73), U.S. patent
application Ser. No. 12/560,106 filed Sep. 15, 2009, now U.S. Publication
No. US-2010-0185142-A1, published Jul. 22, 2010 and entitled Systems and
Methods for Fluid Delivery (Attorney Docket No. G47), and U.S. patent
application Ser. No. 12/649,681 filed Dec. 30, 2009, now U.S. Publication
No. US-2010-0198182-A1, published Aug. 5, 2010 and entitled Method,
System and Apparatus for Verification of Volume and Pumping (Attorney
Docket No. G85), which are each hereby incorporated herein by reference
in their entireties. Reference herein to a disposable may refer to, in
some embodiments, the disposable housing assembly and/or disposable
portion and/or reservoir portion of the various infusion pumps described
in any of the above-discussed infusion pumps.
[0930] However, the apparatus, systems and methods described herein may be
used in any infusion pump or apparatus. Further, the apparatus, systems
and methods described herein may be used to verify the movement of any
plunger, pump actuator, valve and/or other moveable part within any
medical device to confirm that movement and/or displacement occurred.
Further, in addition to confirmation of movement, the determination of
the distance of movement, i.e. the total displacement, may also be used
in some embodiments.
[0931] Referring also to FIG. 150, the various embodiments of the infusion
pump apparatus, methods and systems include the control of the pump and
one or more active valves by contraction of a SMA wire, which, in the
exemplary embodiments, is NITINOL wire. The SMA wire works by applying
current through the wire, which induces heating the wire, and causes a
phase change that result in a contraction of the wire length. The change
in wire length may be exploited by e.g. lever and/or pulley mechanisms to
actuate the pump plunger 2902 and measurement valve 2908.
[0932] The infusion pump system 2900 drives the SMA wires, which may
include two, 2910, 2912 as shown in the exemplary embodiment shown in
FIG. 150, directly from the battery voltage by switching the battery
voltage across the wire to cause a contraction/actuation of the
respective component and then switches off the battery voltage to stop
the contraction. The wire/component starting position is, in some
embodiments, restored by spring forces that oppose the SMA wire
contraction force.
[0933] In the exemplary embodiment, each of the SMA wires 2910, 2912
provides proportional control, i.e. the SMA wire contracts over time and
displaces the respective component over time. Despite this
implementation, the valve components 2904, 2906, 2908 act to occlude or
un-occlude fluid flow, which is a discrete, non-proportional and binary
function. However, the pump piston is operated over a range of stroke
lengths, so proportional control of the pump plunger 2902 is a functional
goal in the exemplary embodiment.
[0934] In some embodiments, proportional control of the pump plunger 2902
may be achieved by monitoring the volume delivered into the volume
measurement chamber 2920 and measured by the volume measurement sensor
assembly/system 2946 and adjusting the amount of time that the pump
plunger 2902 SMA wire 2910 is activated, i.e., adjusting the ontime. This
may result in a closed-loop control of aliquot pumping volume as a
function of SMA wire activation time on a stroke by stroke basis. The
controller scheme in some embodiments also includes additional control
variables which may increase the accuracy of the aliquot pumping volume
to converge on a given target delivery volume.
[0935] Several factors may affect SMA activation including, but not
limited to, one or more of the following: energy into the wire (voltage,
current, time), ambient temperature, heat sinking, pre-tension, SMA wire
variations (diameter, alloy composition, electrical resistance), and/or
assembly variations. Changes in physical parameters, such as the ones
listed above, may result in an inter-pump and intra-pump variation in the
ontime of the pump plunger SMA 2910 that may be expected to result in a
given pumped volume per stroke of the pump plunger 2902 (which may also
be referred to as a given pump delivery volume). As a result, both an
offset in time and a change in the slope of the on-time versus pump
aliquot volume relationship may occur.
[0936] Referring nw also to FIG. 145, a graph that shows the same pump
system 2900 tested over a temperature range of 18 to 38 degrees Celsius
results in a SMA actuation onset time from about 180 to about 310 ms. As
may be seen, the slope is also aggravated at lower temperatures.
Variation in the offset and slope of ontime versus pump delivery volume
may add complexity to the pump system 2900 as compensation for the
variation(s) may be necessary to achieve accurate pump delivery volume.
This phenomenon may also affect the components, e.g., valves and
plungers, actuated by SMA wire in a similar fashion, though valve
function is not proportional.
[0937] At least in part due to the sensitivity of SMA actuation time to
multiple physical variations it may be desirable, in some embodiments, to
directly control one or more components, e.g., the pump plunger 2902
and/or measurement valve 2908 actuator position. This may be beneficial
for many reasons, including, but not limited to, as the position of the
pump plunger 2902 and measurement valve actuator 2908 may be a closer
indication of proportional performance than SMA on-time. Various
embodiments of methods, systems and apparatus for achieving this goal are
described below.
[0938] The ability to sense the position of the pump plunger 2902 and/or
the measurement valve actuator 2908 in the infusion pump system 2900 may
be desired. Although as has been discussed herein, SMA wire may be used
in the exemplary embodiments to actuate the pump plunger and the
measurement valves 2940, in other embodiments, various motors may be used
to actuate the pump and/or the valve(s) including but not limited to a
peristaltic pump, a rotary pump and a piezoelectric actuator. Thus,
disclosed herein, irrespective of the pump actuator, are methods,
apparatus and systems for sensing the position of various components in
the infusion pump system, including but not limited to, sensing the
position of one or more components which may include, but are not limited
to, the pump or displacement component, and one or more active valves
and/or passive valves. Thus, in some embodiments, it may be desirable to
sense the position of inactive valves, e.g., the reservoir valve 2904
and/or the volume measurement chamber inlet valve 2906.
[0939] There are various devices that may be used to sense the position of
the pump plunger 2902 and/or measurement valve actuator 2908. These
include, but are not limited to, one or more of the following:
ultrasonic, optical (reflective, laser interferometer, camera, etc),
linear caliper, magnetic, mechanical contact switch, infrared might
measurement, etc. However, in the exemplary embodiment, due to the small
structure of the infusion pump assembly and/or pump system 2900, it may
be desirable to use a small component so as to utilize a small space with
the sensing component(s). In various embodiments, the device battery life
also may also be considered since the battery size may be limited by the
overall size of the device and battery capacity may be a premium. Sensing
distance may also be a consideration in various embodiments. For example,
where the displacement of the one or more components, e.g., the pump
plunger 2902 and/or the measurement valve actuator 2908 component may be
very small (for example, in the exemplary embodiment, a full displacement
of the pump plunger 2902 may be about 1 mm and a full displacement of the
measurement valve actuator may be about 0.2 mm). The displacement
distances are examples for some embodiments, in other embodiments, the
displacement distances may vary.
[0940] In the exemplary embodiment, a small reflective optical sensor
assembly (hereinafter "optical sensor") that fits into the exemplary
embodiments of the infusion pump system 2900 hardware, as shown and
described, for example, herein, may be used. In some embodiments, the at
least one optical sensor is located in the reusable housing assembly.
However, in other embodiments, part of the at least one optical sensor
may be located in the disposable housing assembly and another part of the
at least one optical sensor may be located in the reusable housing
assembly. The optical sensor, in the various embodiments, has a sensing
range that accommodates the components for which the optical sensor may
be sensing, e.g., in some embodiments, the pump plunger 2902 and/or
measurement valve actuator 2908 displacements. In the exemplary
embodiment any optical sensor may be used, including, but not limited to
a Sharp GP2S60, manufactured by Sharp Electronics Corporation which is a
U.S. subsidiary of Sharp Corporation of Osaka, Japan. In these
embodiments, this optical sensor contains an infra red emitting diode and
infra red sensing detector in a single component package. Light from the
emitter is unfocused and bounces off the sensing surface, some of which
is reflected to the detector. This results in a sensed intensity of light
by the detector that varies as a function of distance/angle to the
reflector. Referring now to FIG. 146, the curve illustrates the
sensitivity of the optical sensor to displacement of a reflective
surface.
[0941] Referring also to FIG. 147, in various embodiments, one or more
optical sensors may be used in the pump system 2900. The one or more
optical sensors may be included in the pump system 2900 such that they
may detect the movement and distance of movement/displacement of one or
more valves 2904,2906, 2908 and/or the pump plunger 2902. With respect to
the pump system 2900, FIG. 147 represents various embodiments of the
location for one or more optical sensors 2956, 2958 to sense the pump
plunger 2902, as well as an embodiment of the location of an optical
sensor 2954 to sense the measurement valve 2908.
[0942] With respect to the embodiments of the location of the optical
sensors 2956, 2958 to sense the pump plunger 2902, although both of these
locations may sense the pump plunger 2902, the distance from the
respective sensor 2956, 2958 to the component, e.g. pump plunger 2902 in
this example, varies the sensitivity of the optical sensor 2956, 2958.
Thus, it may be beneficial to use one or the other optical sensor
location 256, 2958, depending on, for example, but not limited to, the
desired data. In some embodiments, the optical sensors may be placed on
the underneath of the printed circuit board. The placement of the optical
sensors on the underneath of the circuit board allows for independent
sensing of the various components desired in the pump system 2900, for
example, but not limited to, the pump plunger 2902 head, measurement
valve actuating arm 2952 and/or the measurement valve 2908.
[0943] Still referring the FIG. 147, the embodiment shown includes three
optical sensors 2954, 2956, 2958, placed, in some embodiments, on the
bottom of the PCB (not shown) over both pump plunger and valve components
to detect motion of the respective components. The optical sensor 2958
shown over the pump plunger 2902 and the optical sensor 2956 of the pump
plunger actuator arm 2960 essentially sense the same motion, i.e., the
movement of the pump plunger 2902, however, each of the optical sensor
2956, 2958 are a different distance from the respective component being
sensed, i.e., the pump plunger 2902, and thus, each optical sensor 2956,
2958, may result in a different sensitivity of detection. In some
embodiments, one of the optical sensors, e.g., 2956, 2958, may be
preferred for detecting onset motion, i.e., the start of the pump plunger
2902 motion towards the pump chamber 2916, due to the starting distance
from the optical sensor. Both the pump plunger 2902 head and the pump
plunger actuator arm 2960, in some embodiments, are made from white
DELRIN. Thus, in these embodiments, the surface is naturally reflective.
In various embodiments, various materials may be used to manufacture
these components such that they include a naturally reflective surface.
However, in some embodiments, coatings may be added to the surface of the
various components to increase reflection, if desired. In some
embodiments, changes to the geometry of the surfaces may also be made to
modify the reflection.
[0944] In some embodiments, the optical sensor 2954 positioned over the
measurement valve actuator arm 2952 senses rotation. Thus, the change in
reflective intensity is due to a rotational change of the reflecting
surface. In the some embodiments, the measurement valve actuator arm 2952
may be made from a metallic MEMS part. However, in other embodiments, the
measurement valve actuator arm and/or other parts to be sensed, including
the tab discussed below, by the optical sensor may be made from DELRIN or
other materials. In other embodiments, features may be added to change or
modify the reflective pattern. These changes may include, but are not
limited to, adding a tab that extends under the optical sensor 2954.
Additionally, in some embodiments, optical coatings or polishing of the
metal surface, or other treatments/methods, may be used to increase the
refection intensity.
[0945] Referring now also to FIGS. 148A-149B, various embodiments of an
optical sensor are shown. Although in various embodiments, for
illustration purposes, the optical sensor arrangement may be shown with
respect to a measurement valve actuator 2908 or a pump plunger 2902, this
is for illustration purposes only, other embodiments of the various
embodiments of the optical sensor arrangements may include where the
optical sensor arrangement is used with any component, including, but not
limited to, one or more valves and/or one or more pump plungers.
[0946] Referring now to FIGS. 148A-148B, an optical sensor detector 2962
is shown with an LED, and/or light source 2964 and a slot wheel 2966. In
some embodiments, the optical sensor detector 2962 may include one or
more detectors, and depending on the rotation of the slot wheel 2966,
which, in some embodiments, may indicate the position of either a valve
and/or a pump plunger, the LED 2964 will shine through a different slot
in the slot wheel 2966 and the one of the detectors 2962 will detect the
light, indicating the position of the slot wheel 2966.
[0947] Referring now to FIGS. 149A-149B, another embodiments of an optical
sensor, similar to the embodiments shown and described above with respect
to FIGS. 148A-148B, is shown. In this embodiment, the slot wheel 2966
includes a variation in the slots.
[0948] In various embodiments, the optical sensors 2954, 2956, 2958,
utilize infra red light, thus ambient light may not be a variable. In
some embodiments, each optical sensor's light emitting source may be
controlled independently, which may be beneficial for many reasons,
including but not limited to, so that optical cross-talk between the
sensors may be avoided (e.g., in some embodiments, raster through the
sensors one at a time). Optical sensors may be sensitive to drift and
temperature over time, thus, in some embodiments, a "dark" sensor
reading, and/or a temperature sensor reading (in some embodiments, at
least one temperature sensor may be incorporated into the pump system,
and in some embodiments, at least one temperature sensor may be included
in the optical sensor system) may be taken before turning on the
respective emitting light source in order to compensate for offset. In
some embodiments, normalizing the starting reading before inducing motion
may be used to compensate for a change in gain.
[0949] In various embodiments, sensing the pump plunger 2902 may be used
in a number of ways, including but not limited to, onset of motion
detection and determination of pump plunger 2902 position.
[0950] Sensing when the pump plunger 2902 has started to move may be
beneficial for many reasons, including but not limited to, one or more of
the following: removing the offset variation in the SMA wire activation
on-time, in embodiments where ontime is used to control the SMA wire.
Also, in some embodiments the closed-loop controller compensation may be
less confounded because it may be compensating only for variation in
slope of ontime versus volume. This may reduce the pump aliquot volume
variability and result in more accurate fluid delivery versus time.
[0951] Since the pump plunger 2902 moves fluid by displacement, the
position of the pump plunger 2902 may be correlated with the
amount/volume of fluid displaced/pumped. Controlling the position of the
pump piston has many benefits, some of which are discussed below.
[0952] Correlation of the pumped volume with the position of the pump
plunger 2902 may enable the pump system 2900/infusion device to deliver a
desired volume of fluid. Additionally, correlation of pump volume may
reduce delivery variation. A more precise infusion pump, combined, in
some embodiments, with an accurate measurement system, for example,
various embodiments of the volume measurement sensor assembly described
herein, may improve volume delivery consistency.
[0953] Improved correlation of pumping volume to pump plunger 2902
position may enable more accurate transitions from low volume to high
volume delivery. In some embodiments, the pump controller may pump fluid
as a function of SMA wire activation time. Thus, pumping fluid at a fixed
volume may be beneficial. However, in some embodiments, to temporarily
increase the delivery volume, the pump system 2900 may increase the
aliquot delivery rate and hold the volume constant. With more accurate
pumping volume the pump may temporarily aliquot higher volumes to meet
e.g., a bolus delivery, and return to the basal delivery, which, in some
embodiments, may be a lower pumping volume, without losing accuracy of
either basal rate or bolus volume in the process.
[0954] Another benefit may include where, in some embodiments, aliquot
pumping time is a variable used to promote fixed volume aliquot delivery;
aliquot delivery time may be more independent and possibly speed up bolus
volume delivery. Also, determining the pump plunger 2902 position may
also enable a direct determination of malfunction. If, for example, a
failure occurs with the pump plunger 2902 actuator 2960, the control
system having determined the position of the pump plunger 2902, may, in
some embodiments, alert the pump system that the pump has failed, e.g.,
failed open, closed, and/or somewhere in between. In some embodiments,
this may promote safety for the user/patient as the system may identify
failure at a faster rate, preventing over and/or under delivery.
[0955] In the various embodiments where SMA wire is used for pump
actuation and/or active valve actuation, SMA wire activation ontime may
be monitored as a function of pump plunger 2902 position to determine if
the SMA wire is "wearing out" prematurely, i.e., if the SMA wire expected
"life" is being effected. This may be determined, in some embodiments, by
monitoring the ontime necessary to achieve a given pump position over
time.
[0956] In some embodiments, sensing when the pump plunger 2902 has stopped
moving may impart greater certainty to the pump system 2900 regarding
when the pump plunger 2902 has bottomed out and prevent over-driving the
pump plunger 2902. Over driving the SMA wire may reduce the "life" of the
SMA wire and continuing to drive either the pump or a valve after
reaching the desired position is also a waste of electrical/battery
power. Thus, identifying when the pump plunger 2902 has stopped moving,
and or, identifying when the measurement valve actuator 2908 has reached
the desired location, may increase battery life and/or reduce the power
needs of the system, and/or prevent premature SMA wire failure.
[0957] Similarly as with the pump piston, the various valve pistons may be
optically sensed to detect motion of the valve and/or the position of the
valve, either of which may have benefits, including but not limited to,
one or more of the following.
[0958] In some embodiments, where one or more valves is controlled by SMA
wire, sensing when the valve piston has started to move may remove the
offset variation in the SMA wire activation ontime and may give greater
certainty to when the valve starts to open and/or close. Additionally,
sensing when the valve has stopped moving may give greater certainty to
when the valve has opened/closed and prevent over-driving the valve
actuator. As over driving the SMA wire may reduce the "life" of the wire
and continuing to drive any actuator after the valve state is reached is
a waste of electrical power. Thus, identifying when a valve has stopped
moving may increase battery life and/or reduce the power needs of the
system, and/or prevent premature SMA failure. Also, sensing the valve
position may enable the determination of a valve being stuck in an
undesirable position, for example, but not limited to, the measurement
valve actuator 2908 being stuck in the open position.
Optical Position Sensor Control of Infusion Pump System
[0959] Although described herein as an infusion pump system, the optical
sensor control of pumping may be used in various medical devices. For
purposes of this description, the term "pump" broadly refers to valves
and actuators used to move fluid from the reservoir to the user.
[0960] In some embodiments, the pump may be used to move the fluid from
the reservoir to the volume measurement chamber and then to the user.
Referring to FIG. 150, a schematic of an embodiment of an infusion pump
system 2900 is shown. In some embodiments, pumping may be accomplished
using a pump plunger 2902 and three separate valves 2904, 2906, 2908,
where the pump plunger 2902 is controlled by an independently actuated
SMA 2910, and one valve, the measurement valve 2908, is controlled by an
independently actuated SMA wire 2912. As discussed herein, SMA may be
actuated by changing its temperature (in this case by applying an
electrical current) which changes its crystalline structure and causes
the SMA to contract. In the infusion pump system 2900, the SMA wires
2910, 2912 are attached to linkages used to move the valve and pump
plungers. The positions of the pump plunger 2902 and the measurement
valve 2908 are measured using optical sensors (as shown and discussed
above with respect to FIGS. 145-149B). The current applied to the SMA is
modified based on the optical sensor measurements to provide proportional
control of the pump plunger 2902 and measurement valve 2908 positions.
[0961] In some embodiments, the pump sequence is as follows. First, the
pump plunger SMA 2902 is actuated which simultaneously moves the
reservoir valve plunger 2914, which occludes the flow path between the
pump chamber 2916 and the reservoir 2918. The pump plunger 2902 forces
the fluid in the pump chamber 2916 past the passive volume measurement
sensor chamber inlet check valve 2906 and into the volume measurement
sensor chamber 2920. The fluid is held in the volume measurement sensor
chamber 2920 by the measurement valve 2908 while a volume measurement
taken. Once the volume measurement is completed, the measurement valve
SMA 2912 is actuated, which opens the measurement valve 2908 and the
fluid is released from the volume measurement sensor chamber 2920 to the
tubing set 2922, which may, in some embodiments, lead to a user/patient
which may, in some embodiments, lead to the delivery of medical fluid to
the user/patient.
[0962] Referring now also to FIG. 151, the actuation of each SMA wire
2910, 2912 is accomplished using two field effect transistors (FET). A
high side FET, which, in some embodiments, is controlled by the
supervisor processor 2926 (described above), and provides an on/off
switch between the battery supply voltage and the SMA wires 2910, 2912.
In some embodiments, the high side FET is normally off and may prevent or
reduce the occurrence of a single-point electrical fault from actuating
the pump. A low-side FET, which, in some embodiments, is pulse-width
modulated (PWM), is controlled by the command processor 2924 and provides
control of the amount of current flowing through the SMA wire 2910, 2912.
[0963] In some embodiments, both the position of the pump plunger 2902 and
measurement valve plunger 2908 is measured using at least two optical
position sensors. However, in some embodiments, a single optical sensor
may be used to measure both the pump plunger 2902 and the measurement
valve plunger 2908. This allows the command processor 2924 to provide
closed-loop control of the plunger pump 2902 and measurement valve
plunger 2908 position by comparing the optical sensor output to a target
position and modifying the PWM of the low-side FET. In addition, in some
embodiments, voltages are measured at various positions. This enables, in
some embodiments, the SMA controller to detect various conditions of the
system including, but not limited to, one or more of the following: a
broken SMA wire, a failed FET, and/or a depleted battery.
[0964] For the following discussion, the following nomenclature may be
used:
TABLE-US-00013
m Total mass of the nitinol wire
T.sub.n Current nitinol temperature
T.sub.i Initial nitinol temperature
T.sub.a Ambient temperature
I Current
V Applied voltage
R Electrical Resistance
h Heat transfer coefficient [W/K]
C Heat capacity [J/kg/K]
.eta. Duty cycle
SMA Modeling
[0965] A thermal model of the SMA wires and a linear model of the pump
plunger 2902 is described below. As discussed below, the position of the
pump plunger 2902 is measured. In some embodiments, the displacement of
the pump plunger 2902 is measurement, i.e., the distance travelled from
the starting point to the ending point may be measured.
Modeling the SMA Wire
[0966] The basic heat transfer equation for a constant current going
through a wire with resistance R may be as follows. This neglects any of
the thermal effects of the phase change in the SMA.
mC dT N dt = Q i n - Q out =
I 2 R - h ( T N - T a ) [ EQ #156 ]
##EQU00101##
[0967] Solving this equation gives the expression:
T N = T a + ( T i - T a ) e - t .tau. + I
2 R h ( 1 - e - t .tau. ) e - t .tau.
Where .tau. = mC h [ EQ #157 ] ##EQU00102##
[0968] Thus, at time 0 the SMA temperature will be T.sub.i, and at
t.fwdarw..infin. the temperature will approach a steady state value of
( T a + I 2 R h ) . [ EQ #158 ] ##EQU00103##
[0969] Solving for the required on time to get the SMA to a given
temperature:
t .tau. = ln ( 1 - h I 2 R ( T i - T a ) 1
- h I 2 R ( T N - T a ) ) [ EQ #159 ]
##EQU00104##
This may be approximated using a Taylor's Expansion as:
t .apprxeq. mC I 2 R [ ( T N - T i ) - 1 2 h
I 2 R [ ( T a - T N ) 2 - ( T a - T i ) 2 )
] [ EQ #160 ] ##EQU00105##
This may also be written in terms of the applied voltage:
t .apprxeq. mCR V 2 [ ( T N - T i ) - 1 2 hR V
2 [ ( T a - T N ) 2 - ( T a - T i ) 2 ] ]
[ EQ #161 ] ##EQU00106##
Thus, the ontime needed to produce a given strain in the SMA will be
inversely proportional to the square of the applied voltage. In some
embodiments, unregulated voltage is applied to the SMA for energy
efficiency, thus, the applied voltage may vary with the battery voltage.
[0970] The internal battery impedance causes a voltage drop as the load is
applied during each cycle of the PWM. In addition, the battery open
circuit voltage drops over the course of the actuation. Both the battery
open circuit voltage and impedance will change as the battery is
discharged. The net result is that the electrical power applied to the
SMA for a fixed duty cycle is variable. The repeatability of the SMA
actuator may be improved by, in some embodiments, measuring the battery
voltage and adjusting the duty cycle to provide power that is more
consistent. In some embodiments, however, the position of the measurement
valve plunger 2908 and the pump plunger 2902 may be measured directly and
incorporated into a feedback loop. This may minimize any effects of the
battery voltage variation.
Pulse Pump Modeling
[0971] An example of a relationship between the linear displacement of the
pump plunger 2902 (as measured by the optical sensor) and the delivered
volume is shown in FIG. 152. In some embodiments, the pump plunger 2902
may exhibit a dead zone where the pump plunger 2902 may not be in contact
with the membrane covering the pump chamber 2906. Once the pump plunger
2902 reaches the pump chamber 2916 membrane there may be a relatively
linear relationship between pump plunger 2902 displacement and volume
until the pump plunger 2902 contacts the bottom of the pump chamber 2906.
[0972] A model of the pump plunger 2902 is shown in FIG. 153 as a gain
2930 element with a dead zone 2928 and saturation 2932 limit. The
idealized linear model of a pump plunger 2902 that neglects the dead zone
2928 and saturation 2932 is then a static gain element 2930:
.DELTA..nu.(k)=K.delta..sub.target(k) [EQ#162]
where .DELTA..nu.(k) is the change in volume during a single pump pulse,
which refers to one actuation of the pump plunger 2902 by the SMA, the
pump plunger 2902 moving from a starting point towards the pump chamber
2916 and reaching an end point, then returning to a stopping point. The
total volume delivered may be the sum of the individual pulses:
v ( n ) = k = 0 n K .delta. target ( k )
[ EQ #163 ] ##EQU00107##
This may be expressed as a transfer function in the discrete domain:
G p ( z ) = v ( z ) .delta. target ( z ) =
K z z - 1 [ EQ #164 ] ##EQU00108##
SMA Controller
Feedback Controller
[0973] Referring now to FIGS. 154B and 154C, during a typical actuation,
as shown in the FIGS., target position as a function of time and actual
position as measured by the optical sensor as a function of time are
shown in FIG. 154B. FIG. 154C shows the controlled variable, the duty
cycle 2902 is the duty cycle that may be changed in response to errors in
following the position trajectory. It should be noted that the term "ADC
counts" refer to the counts as read by the analog to digital converter
("ADC") on the MSP 430 command processor. The ADC counts are proportional
to the voltage of the at least one optical sensor. Thus, the output of
the at least one optical sensor will be a voltage which is read by the
ADC (analog to digital converter).
[0974] In some embodiments, and referring also to FIGS. 154A, 154B and
154C, the SMA controller may use a proportional controller 2936 with a
fixed feed-forward 2934 to control the position of the pump plunger 2902
or measurement valve plunger 2908. The heating of the SMA wire 2910, 2912
may be an integrating process, thus, uses a proportional controller 2936
for controlling the position of the plungers 2902, 2908. In some
embodiments, a fixed duty-cycle feed forward 2934 term may be used to
provide fast initial heating of the SMA wire 2910, 2912. The output of
the controller is limited to a valid PWM range (0% to 100%), where valid
may be, in some embodiments, referring to a combination of that which the
system may perform together with potential SMA stress and/or strain
and/or saturation factors which may contribute to overall SMA wire life.
In some embodiments, the signal from the one or more optical sensor is
low passed filtered 2938 with, in some embodiments, a single-pole
discrete filter. In some embodiments, the PWM frequency is 20 kHz, which
moves it outside the audible range, which may be beneficial for many
reasons, including, but not limited to, one or more of the following:
user comfort and improving the user experience while pumping as the PWM
frequency is outside the audible range. In some embodiments, the PWM
output is updated at a frequency of 5 kHz, but in other embodiments, the
frequency may vary.
Voltage Sensing and Timing
[0975] In some embodiments, the battery voltage sensing is done through a
resistor-divider to an ADC input on the MSP430. The minimum time needed
to sample the voltage may be represented in EQ#165:
t.sub.sample(R.sub.s2 k.OMEGA.)ln 2.sup.13(40pF)+800 ns [EQ#165]
where R.sub.s is the source impedance. The minimum sampling time may
therefore be 1.77 microseconds. A sampling time of 2 microseconds may be
used in some embodiments, however, in other embodiments the sampling time
may be greater than or less than 2 microseconds. In some embodiments the
minimum sampling time may be less than 1.77 microseconds or greater than
1.77 microseconds depending on the value of R.sub.s. In some embodiments,
the sampling is done synchronous with the PWM and timed to be a fixed
interval from the end of the high cycle of the PWM. Referring now to FIG.
155, in some embodiments, as presented in FIG. 155, the ontime of the PWM
duty cycle cannot be/should not be less than the ADC sampling time. As a
result, in this embodiment, the voltage measurement will be higher than
the actual battery voltage for duty cycles under 4%. In the exemplary
embodiment, the control algorithm is updated every 4.sup.th PWM period to
give time for the Interrupt Service Routine ("ISR"): to complete.
However, in various embodiments, the control algorithm may be updated
using intervals other than every 4.sup.th PWM period.
SMA Target Trajectory
[0976] In some embodiments, the outer "volume" loop (described in more
detail below with respect to the volume controller) provides a target
final pump plunger 2902 position to the inner pump plunger 2902 position
control loop. The inner pump plunger 2902 position controller, in some
embodiments, brings the pump plunger 2902 to this target position with
minimum overshoot because once fluid is moved past the measurement valve
2940 it may not be brought back to the pump chamber 2916. Thus, it may be
desirable in some embodiments to minimize and/or prevent overshoot, and
this may be desirable for many reasons, including, but not limited to,
safety to the user as it may be beneficial to prevent an "overdelivery"
of medical fluid. In some embodiments, this may be accomplished where the
pump plunger 2902 position controller generates a position trajectory,
i.e., a series of pump plunger 2902 target positions as a function of
time that may be followed by the SMA actuator. This may be compared with
other embodiments including a step change in target position which may
increase the incidence of overshoot in some instances.
[0977] Referring also to FIG. 156, the pump plunger 2902 target position,
in some embodiments, has two parts, which are shown: an initial flat
region and a linear region. The initial flat region 2942 is where the
pump plunger 2902 position is not changing to allow the SMA 2910 to reach
the transition temperature. The linear region 2944 is where the pump
plunger 2902 is brought to its final position over a fixed time interval.
Because the time interval is fixed, the target pump plunger velocity may
be less for smaller actuations. In some embodiments, this may be
beneficial for many reasons, including, but not limited to, improved
controller accuracy for small volume deliveries.
[0978] Referring to FIG. 157, the measurement valve plunger 2908, in some
embodiments, may be controlled differently from the pump plunger 2902 (as
described above) because it is binary in its operation, i.e., the
measurement valve 2940 is either in an open position or a closed
position. The measurement valve plunger 2908 position controller,
therefore, in some embodiments, moves the measurement valve plunger 2908
to the "open" position and then, in some embodiments, holds the
measurement valve plunger 2908 in the open position which may allow the
fluid ample time to fully drain from the measurement chamber 2920. This
method may be beneficial for many reasons, including, but not limited to,
adding the "open and hold" phase to the measurement valve plunger 2908
trajectory which may require less strain on the SMA wire 2912, which may
increase the SMA wire 2912 "life"/duration of useful/usable performance
for actuation. Thus, adding the "open and hold" phase, rather than, in
some embodiments, continuing to move the measurement valve plunger 2908,
may require less strain on the SMA wire 2912, thus, increasing the SMA
wire 2912 "life".
Safety Check and Fault Handling
[0979] The pump controller in various embodiments includes a number of
safety checks designed to provide greater safety to the pump system 2900
operation. These including, but are not limited to, preventing the SMA
actuator from "browning out" the electrical system if the battery voltage
is too low and guarding against electrical failures in the SMA drive
circuit. Thus, the pump controller monitors and ensures that the SMA wire
and the drive circuit, or source of electrical energy, functions so as to
allow for function of the pump system 2900.
[0980] In some embodiments, these safety checks include supply voltage
monitoring. In some embodiments, the supply voltage is measured once
during each period of the low-side switch PWM and is used in the feedback
controller. However, in other embodiments, the pump controller may
measure the supply voltage more or less often. However, this measurement
is also checked, in some embodiments, to verify that the supply voltage
is within the range of expected battery voltages. Where the measurement
is outside this range, the actuation may be stopped and in some
embodiments, an alarm may be posted by the command processor. The failure
of this integrity check could indicate one or more, but not limited to,
the following: a failure of voltage sensing circuit, a failure of the
battery, and/or a depleted battery. Although supply voltage monitoring is
not the primary mechanism for detecting a depleted battery--that may also
be done by the battery gauge--in the event of a failure of the battery
gauge, supply voltage monitoring allows the pump system 2900 to terminate
the high-current SMA actuation before actuating same may deplete or "pull
down" the battery voltage to a level below a threshold needed for the
processor voltage regulators.
[0981] The integrity of the switches and SMA wires 2910, 2912, are also
monitored during each actuation. This safety routine verifies the safety
of the system which may, in some embodiments, may including, but are not
limited to, one or more of the following: verification that the switches
are functioning correctly; and verification that the measurement valve
plunger 2908 and the pump plunger 2902 are not actuated simultaneously.
These verifications may provide greater safety to the pump system 2900
for many reasons, including, but limited to, actuating the pump plunger
2902, i.e., pumping fluid from the reservoir, while the measurement valve
plunger 2908 is in the open position, thereby pumping fluid to the tubing
set 2922 without holding the fluid in the measurement chamber 2920. In
some embodiments, this may be desirable and beneficial, e.g., in those
embodiments where the volume measurement sensor 2946 includes a method
for determining the volume of the fluid in the measurement chamber 2020
which includes holding the fluid in the measurement chamber 2020 during
the actual volume measurement. Some embodiments of the volume measurement
sensor 2946 may not require the measurement valve 2940, but for those
that do, the safety routine described above ensures the volume
measurement sensor 2946 may perform measurements according to the method.
In some embodiments, to perform these safety-checks the supervisor
processor monitors the voltage above the low-side switches using three
digital inputs. Referring also to FIG. 158, the electrical architecture
is shown for a single strand of SMA wire. However, in some embodiments,
the SMA wires share the same high-side switch, but have their own
low-side switch and voltage monitor line.
[0982] Still referring to FIG. 158, in some embodiments, the safety-check
routine proceeds as follows. The command processor 2924 requests SMA
power from the supervisor processor 2926. The supervisor processor 2926
receives the message and proceeds to perform the following: the
supervisor processor 2926 verifies that the high-side SMA voltage is low.
If the voltage is high, the supervisor processor 2926 may indicates that
the power FET has failed closed. The supervisor processor 2926 closes the
SMA power switch 2948 and the supervisor processor 2926 verifies that the
high-side SMA voltage is high. If it is low the supervisor processor 2926
indicates that the high-side FET has failed open. The supervisor
processor 2926 verifies that the low-side SMA voltage is high. If the
voltage is low the supervisor processor 2926 indicates that the SMA wire
is broken or the low side FET has failed closed. The supervisor processor
2926 then sends a message to the command Processor 2924 that the SMA
power is on. The command processor 2924 receives the SMA power on message
and starts the SMA actuation. At the same time, the supervisor processor
2926 monitors the SMA monitor lines verifying that only the designated
SMA wire is being actuated and that the low-side FET has not failed open.
The command processor 2924 completes the actuation and sends a SMA
power-off message to the supervisor processor 2926. At this point, the
supervisor processor 2926 turns off the SMA power and sends a
confirmation message.
[0983] In various embodiments, the pump system 2900 may include additional
safety checks and/or, the process for the above-described safety checks
may vary. In some embodiments, in addition to the safety checks described
above, the supervisor processor 2926 may turn off the SMA power switch
2948 and alarm if the supervisor processor 2926 does not receive a "power
off" request from the command processor 2924 within a fixed period of
time. Thus, in some embodiments, if the command processor 2924, for
example, freezes mid-SMA actuation, and continues to actuate the SMA, and
thus, does not command the SMA power switch 2948 to turn off, the
supervisor processor 2926 may determine that the command processor 2924
has not turned off the SMA power switch, and the supervisor processor
2926 may post an alarm. This protects the pump system 2900 from command
processor 2924 faults which may provide another safety layer to the pump
system 2900.
Optical Sensor Monitoring
[0984] In the exemplary embodiment, the command processor 2924 checks the
integrity of each of the at least two optical sensors during every
actuation. However, as discussed above, in some embodiments, the pump
system 2900 may include at least one optical sensor where the optical
sensor is used to determine the position of the pump plunger 2902 but not
the measurement valve plunger 2908. In some embodiments, the pump plunger
2902 may include at least two optical sensors determining the position of
the pump plunger 2902. Further, and as discussed above, in some
embodiments, the pump system 2900 may include additional optical sensor
to determine the position of additional valves and or membrane position.
Thus, for purposes of the discussion, the term "optical sensor" is not
meant to be limited to a single optical sensor, rather, applies to the at
least one optical sensor that may be included in the pump system 2900 in
some embodiments. Where more than one optical sensor is included in the
pump system 2900, in some embodiments, the discussion below may apply to
each optical sensor.
[0985] In some embodiments, the command processor 2924 may check the
optical sensor signal output, which, in some embodiments, may include
confirming that the optical sensor is within an expected range at the
start of actuation, :Sensor Check: range check, looking at the optical
sensor and if not within the expected range at the start of the
actuation, then it may conclude it's broken] before each actuation. In
some embodiments, if the output of the optical sensor is outside the
normal operating range the command processor 2924 may post an alarm.
[0986] The command processor may, in some embodiments, post an alarm if
the output of the optical sensor does not change significantly during an
actuation. This may be beneficial for this optical sensor output may
indicate, e.g., an electrical fault which may produce an optical sensor
output that is in range but not related to the plunger displacement for
which the optical sensor is determining. Also, in some embodiments,
allowances may be made for optical sensor noise and/or drift.
Saturation
[0987] Referring also to FIGS. 159A and 159B, in some embodiments, to
maximize the "life" of the SMA wire (which include at least one SMA wire,
and in some embodiments, may be more than one SMA wire), it may be
desirable to minimize the number of times the pump plunger/measurement
valve plunger (and/or any valve/plunger that is being actuated by a SMA)
"bottoms out" at the end of its travel. When the plunger reaches the end
of its travel, it cannot move any further so it falls behind the target
position. If the tracking error (the difference between the target
position and actual position) exceeds a fixed threshold, the plunger is
assumed to have "bottomed out" and the power to the SMA wire is turned
off. Allowances are made to prevent false detects.
[0988] If the plunger is detected to have "bottomed out" twice in a row,
the maximum allowed target position may be reduced to prevent the plunger
from bottoming out again. In some embodiments, the maximum target
position may not be reduced the first time the plunger is detected to
have "bottomed out" to prevent any false detections of plunger saturation
from limiting the plunger travel.
Delivery Controller
[0989] The delivery controller delivers a discrete dose of fluid (which in
some embodiments, as discussed above, may be any fluid, including, but
not limited to, a medical fluid, e.g., insulin) each time it is commanded
by the therapy layer. The delivery controller, in some embodiments, does
not track nor control the therapy, e.g., basal programs, boluses, or the
timing of the delivery; rather, the therapy is controlled by the therapy
layer. The delivery controller, in some embodiments, has a primary
responsibility to deliver a dose of fluid when commanded and to measure
the actual fluid delivered (using the volume measurement sensor 2946),
and also, to adjust the pump plunger 2902 command to minimize any volume
delivery error. Thus, where the pump plunger 2902 target position is met,
the delivery controller determines whether the volume of fluid delivered
is as expected and if not, to adjust the pump plunger 2902 command.
[0990] In addition, in some embodiments, the delivery controller may
confirm and process a variety of system checks including, but not limited
to, detecting occlusions, detecting an empty reservoir, and/or system
faults that may affect the delivery of fluid to the tubing set 2922,
which, in some embodiments, may be connected by way of a cannula to the
patient/user of the system. If one or more faults are detected by the
delivery controller, the delivery controller may, and in some
embodiments, will always, enter a failsafe state preventing further
delivery until and unless the at least one detected fault is resolved.
The delivery controller reports faults detected to the therapy layer. The
term failsafe may refer to a state of non-delivery in response to a
determined failure, following alerting the user/patient that the system
is entering a failsafe mode.
[0991] For the following discussion, the following nomenclature may be
used:
Term Definition
TABLE-US-00014
[0992] G.sub.p(z) Pulse pump discrete transfer function
G.sub.c(z) Controller discrete transfer function
K.sub.p Controller loop gain
T.sub.l Controller Integrator time constant
z Complex argument for the discrete transform
x ( z ) = Z { x ( n ) } = n = 0 .infin. x
( n ) z - n ##EQU00109##
e Delivery error
r(z) Target volume trajectory
K Pulse pump gain
Volume Controller
[0993] Referring also now to FIG. 160, in some embodiments, the primary
function of the delivery controller may be to provide closed-loop control
of the delivered fluid volume. The delivery controller accomplishes this
function, in some embodiments, by taking the measured volume change (this
is the difference between the AVS/volume measurement sensor measurement
with the AVS/volume measurement sensor chamber full and the AVS
measurement with the chamber empty), comparing it to the target volume,
and setting the pump plunger 2902 target displacement accordingly.
Referring also to FIG. 161, the schematic shows the outer volume loop as
well as the inner voltage loop described above.
[0994] As shown in FIGS. 161-162, the volume controller architecture on
the total delivered volume and a feed-forward term based on the target
volume for the current delivery is shown. As shown in this embodiment,
the target volume and measured volume changes (dV AVS) are integrated
before being passed into the feedback controller; there is no direct
feedback on the error from an individual delivery.
Feedback Controller
[0995] Referring now to FIG. 162, in some embodiments, the volume
controller may include the architecture, as shown, with integrator
saturation and anti-windup. The discrete transfer function is shown below
for the region where the integrator is active. A unit time delay is
included to account for the 1-frame delay between the volume measurement
and its use in the feedback loop.
G c ( z ) = K p ( 1 + 1 T I z z - 1 ) 1
z [ EQ #166 ] ##EQU00110##
[0996] The pump plunger 2902 displacement versus volume delivered transfer
function (input is the pump plunger position, and the output is the
volume delivered) between total volume delivered and pump plunger 2902
may be modeled as a simple discrete integrator.
G p ( z ) = v ( z ) t on ( z ) = K
z z - 1 [ EQ #167 ] ##EQU00111##
[0997] The forward path transfer function may then be written as follows.
An additional unit time delay may be added to account for the fact that
the AVS measurement/volume measurement sensor measurement will be from
the previous delivery. A corresponding unit delay was also added to the
target input.
G c ( z ) G p ( z ) = K p ( 1 + 1 T
I z z - 1 ) K ( z z - 1 ) 1 z = K
p K ( 1 + 1 T I ) z - 1 ( z - 1 ) 2 [
EQ #168 ] ##EQU00112##
[0998] The steady-state volume error for this type of controller when
following an input r (z) is shown below:
e ( z ) r ( z ) = 1 1 + G c G p
= ( 1 - z - 1 ) 2 ( 1 - z - 1 ) 2 + KK p [
( 1 T I + 1 ) - z - 1 ] z - 1 [ EQ #169
] ##EQU00113##
[0999] The pump system 2900 may typically be following a ramp target
volume trajectory (piecewise constant delivery rate). This input may be
described in the discrete domain as follows:
r ( z ) = C z ( z - 1 ) 2 [ EQ #170 ]
##EQU00114##
[1000] The steady state flowing error can then be found using the discrete
final value theorem applied to the plant and controller derived above:
lim t .fwdarw. .infin. e ( t ) = lim z
.fwdarw. 1 [ ( 1 - z - 1 ) e ( z ) ] =
lim z .fwdarw. 1 [ ( ( 1 - z - 1 ) 3 ( 1 - z
- 1 ) 2 + KK p [ ( 1 T I + 1 ) - z - 1 ] z -
1 ) ( z - 1 ( 1 - z - 1 ) 2 ) ] =
0 [ EQ #171 ] ##EQU00115##
[1001] So a PI controller will theoretically have zero steady state error
when following a ramp input in volume.
Controller Feed-Forward
[1002] Referring also to FIG. 163, in some embodiments, to improve the
trajectory following of the controller, a non-linear feed-forward term
may be added to, e.g., compensate for the pulse pump dead-band. In some
embodiments, this feed-forward term provides a "best guess" of the pump
plunger 2902 displacement for a given target volume by inverting the
idealized pump plunger 2902 model described above with respect to the
delivery controller. Pump system 2900 characteristics are different for
different reusable housing assemblies, disposable housing assemblies, and
reservoir fill volumes, i.e., the volume of fluid in the reservoir. Thus,
this feed-forward term may generally produce some error that may need to
be corrected by the feedback controller.
Initialization of the Feed-Forward Parameters
[1003] The gain and offset used in the feed forward controller, shown in
FIG. 164, are initialized during the start-up test based on the measured
pump characteristics.
Least Square Recursive Filter
[1004] The gain and offset parameters of the feed-forward controller are
adjusted as the pump is operating. Thus, the slope and offset of the
model are continuously updated based on the AVS measurements/volume
measurement sensor measurements to improve the accuracy of the
feed-forward model. The "learning" algorithm may be based on a linear
exponentially forgetting least square recursive filter. The time constant
is set such that it adapts slowly compared to the feedback controller
(FIG. 162) and the two do not have significant interaction. If the
feed-forward term was never changed, it would have no effect on the
stability of the feedback controller.
[1005] The feed-forward model is updated using a recursive least-square
estimator. The function we are fitting is as follows:
y(n)=mx(n)+b [EQ#172]
[1006] The dependent variable x is the delivered volume and the
independent variable, y, is the pump plunger 2902 target
position/displacement. In vector form, this may be written:
y ( n ) = w T x ( n ) w = [ m n
b n ] and x n = [ x n , 11 1
] [ EQ #173 ] ##EQU00116##
[1007] It may be noted that x.sub.n is the vector x at time step n, and
x.sub.n,11 is the 1.sup.st element of the vector x at the time step n.
The function being optimized is:
y n = m n x n + b n = w T x = [ m n
b n ] [ x n , 11 1 ] [ EQ #174 ]
##EQU00117##
[1008] The error for a given time step, n may be written:
e.sub.n=y.sub.n-(m.sub.n-1x.sub.n+b.sub.n-1) [EQ#175]
[1009] To update the w vector based on the error signal, the gain matrix
is first updated:
g n = [ p n - 1 , 11 x n , 11 + p n - 1 ,
12 p n - 1 , 21 x n , 11 + p n - 1 , 22 ]
{ .lamda. + p n - 1 , 11 x 2 + ( p n - 1 , 12
+ p n - 1 , 21 ) x n , 11 + p n - 1 , 22 } - 1
[ EQ #176 ] ##EQU00118##
[1010] The inverse is of a scalar so no matrix inversion is required. The
covariance matrix may then be updated for the next time step:
P n = .lamda. - 1 [ p n - 1 , 11 ( 1 - g
n , 11 x n , 11 ) - p n - 1 , 12 g n , 11
p n - 1 , 21 ( 1 - g n , 11 x n , 11 ) - p n
- 1 , 22 g n , 11 p n - 1 , 12 ( 1 - g n ,
12 ) - p n - 1 , 11 g n , 12 x n , 11 p
n - 1 , 22 ( 1 - g n , 12 ) - p n - 1 , 21 g n ,
12 x n , 11 ] [ EQ #177 ] ##EQU00119##
[1011] The coefficients can then be updated based on the gain vector and
the error:
[ m n b n ] = [ m n - 1 b n - 1 ]
+ e n g n [ EQ #178 ] ##EQU00120##
[1012] Taking advantage that the covariance matrix is symmetric, the
method and/or algorithm may be written more computationally efficiently.
This may, in some embodiments, be beneficial for many reasons, including,
but not limited to, efficient implementation in software.
[1013] In some embodiments, the filter is only valid if the pump plunger
2902 is operating in its linear range, so the value may only be updated
if the measured volume is in the range of 0.1 uL to 2.1 uL, for example,
where this range is in the linear range. In some embodiments, the
recursive filter may not be effective if the measurements are not
sufficiently "signal rich", i.e., where too many deliveries are performed
at a single operating point the linear fit may converge to a solution
that may not be valid once the pump plunger 2902 being operation over the
full range. To guard against this possible "localized" solution, the
algorithm, in some embodiments, may not be updated where the diagonal
terms of the covariance matrix exceed a set threshold.
Delivery Fault Detection
[1014] In addition to providing closed-loop control of the volume
delivered by the pump system 2900, the delivery controller, in some
embodiments, may also detect fault conditions associated with fluid
delivery. A variety of fault detection methods are described below, one
or more of which may be included in various embodiments of the delivery
controller.
[1015] In some embodiments, the delivery controller monitors, amongst
possible additional functions, the total volume error, which may be
defined as the cumulative volume error of all the deliveries since the
delivery controller was last reset. If the delivered volume exceeds the
target volume by more than a specified amount, which indicates an
over-delivery, the delivery controller, in some embodiments, may post a
pump fault and switch to a failsafe mode, which is described above.
Conversely, if the target volume exceeds the measured volume by a
specified amount, which indicates under-delivery, the delivery
controller, in some embodiments, may post a pump fault and switch the
pump system 2902 to a failsafe mode, which is described above. In some
embodiments, the under-delivery tolerance may be programmable by the
user/patient and further, in some embodiments, the tolerance may include
a high and low sensitivity setting.
[1016] Thus, where the delivery controller determines that the cumulative
volume error is such that a either an over-delivery or under-delivery
threshold has been met, which threshold may be set based on safety to the
user/patient, the delivery controller may signal a pump fault condition
and the pump system 2902 may be shut down, with at least one indication
to the user/patient, such that the pump system 2902 avoids over delivery
and under delivery at unsafe levels. Thus, in various embodiments, the
pump system 2902 includes a determination of the volume of over delivery
and/or under delivery and a threshold tolerance of same where when the
threshold is reached, the pump system 2902 may enter failsafe mode.
Occlusion Detection
[1017] In some embodiments, the deliver controller monitors the volume of
fluid that both flows into and out of the volume measurement chamber 2920
and, in some embodiments, may determine whether the tubing set 2922 may
be occluded. In some embodiments, there are two parallel methods used for
detecting an occlusion, which may be termed the total occlusion method
and the partial occlusion method. The total occlusion detection method
monitors the flow into and out of the volume measurement chamber 2920
during a single delivery of fluid. The partial occlusion detection method
monitors for a gradual build-up of fluid in the volume measurement
chamber 2920.
[1018] The residual volume for an individual delivery may be defined as
the difference between the volume flow into the volume measurement
chamber 2920, which may be referred to as the "pumped volume" and the
volume flowing out of the volume measurement chamber 2920, which may be
referred to as the "delivered volume":
.quadrature..nu..sub.res=.DELTA..nu..sub.pump-.DELTA..nu..sub.delivered
[EQ#179]
[1019] This is equivalent to the difference between the final and initial
variable volume estimates:
.quadrature..nu..sub.res=V.sub.final-V.sub.initial [EQ#180]
[1020] Under normal operation, in some embodiments, the residual volume
may be close to zero at steady state. In some embodiments, the residual
volume may be the fundamental metric for detecting both total and partial
occlusions.
Total Occlusion
[1021] In the event of a total occlusion of the fluid exit path, which may
also be referred to as the tubing set 2922 and the cannula as well as the
fluid path in the disposable housing assembly downstream from the volume
measurement chamber 2920, the residual volume in the volume measurement
chamber 2920 may be approximately the same size as the volume pumped,
i.e., the volume of fluid pumped into the volume measurement chamber
2920. Thus, in these circumstances, fluid has been pumped into the volume
measurement chamber 2920, however, little or no fluid may have left the
volume measurement chamber 2920. In these circumstances, in some
embodiments, a threshold residual volume may be used as an indicator of a
total occlusion. In some embodiments, the total occlusion detection
threshold may be set based on the cumulative pumped volume, i.e., the
total volume of fluid pumped. A linearized model of the fluid flow out of
the volume measurement chamber 2920 may have the form:
V .cndot. avs .varies. V avs .tau. [ EQ #181 ]
##EQU00121##
[1022] Where V.sub.a.nu.s is the volume of the variable volume chamber
2950.
[1023] Larger pumped volumes/larger volumes of fluid pumped into the
volume measurement chamber 2920, may result in larger delivered volumes
for the same measurement valve 2940 open time and tubing set 2922 flow
impedance. In some embodiments, therefore, the residual volume threshold
for occlusion is therefore calculated as a fraction of the total volume
pumped:
T.sub.O=.rho..sub.o.DELTA..nu..sub.pump [EQ#182]
[1024] where .rho..sub.O is a value less than one. An exemplary value for
.rho..sub.O is 0.15, which means the delivery controller may detect a
total occlusion if less than 85% of the fluid pumped into the volume
measurement chamber 2920 is delivered/pumped out of the volume
measurement chamber 2920 (and in some embodiments to the tubing set 2922
and to the user/patient). Determination of a total occlusion may be as
follows:
.PHI. O = { 1 if v res > T o 0
otherwise [ EQ #183 ] ##EQU00122##
[1025] Where .PHI..sub.O is the total occlusion detection indicator. In
some embodiments, the pump system 2902 may not alarm immediately after
the total occlusion detection indicator has been set to "1", rather in
some embodiments, an alarm may be posted once the total occlusion
detection indicator remains positive for a preset number of consecutive
deliveries to allow time for the occlusion to clear through regular
operation of the pump system 2902, which, in some circumstances, may be
accomplished. In various embodiments, the number of occluded deliveries
permitted is variable and may, in some embodiments, be
pre-set/preprogrammed and/or may be based on a user/patient configurable
occlusion sensitivity setting.
[1026] In some embodiments, in the event that an occlusion clears on its
own, the fluid may once again flow out of the volume measurement chamber
2920. Thus, in some embodiments, the logic for clearing the total
occlusion is related to the delivered volume, .nu..sub.del being greater
than a given threshold. This cleared-occlusion threshold may be, in some
embodiments, calculated as a fraction of the total volume pumped for a
given delivery plus the accumulated residual volume, if any, from
previous deliveries, which may be represented as follows:
T u = .rho. u ( .DELTA. v pump + v residual ,
total ) Or [ EQ #184 ] .PHI. O = { 0
if v del > T u 1 otherwise [ EQ #185 ]
##EQU00123##
[1027] Combining these two, the total occlusion update logic is as
follows:
.phi. O [ n + 1 ] = { 1 if v res [ n
+ 1 ] > T O 0 if v del [ n + 1 ] >
T u otherwise .PHI. O [ n ] [ EQ
#186 ] ##EQU00124##
[1028] In some embodiments, an increase in the residual volume may be an
indication that an occlusion has occurred, however, the residual volume
returning to zero may not necessarily be an indication that an occlusion
has cleared. This is because the pump plunger 2902 may, in some
instances, only be able to pump one or two deliveries following an
occlusion due to the build up of back-pressure in the volume measurement
chamber 2920. Thus, once the pump system 2900 has reached this condition,
the change in residual volume becomes close to zero, thus, no fluid flows
into the volume measurement chamber 2920 and no fluid volume flows out of
the volume measurement chamber 2920. As a result, in some embodiments,
the delivered volume, instead of the residual volume, may be used for the
condition to clear a total occlusion indication.
[1029] In various embodiments, partial occlusions result in an
accumulation of residual volume in the volume measurement chamber 2920,
but this accumulation may occur over time at a low enough rate that the
total occlusion detection logic may not detect the accumulation. As a
result, in some embodiments, a second method, i.e., partial occlusion
method, may be used which integrates the residual volume of individual
deliveries and uses this sum to detect a slow build-up of volume
characteristic of a partial occlusion. Additionally, any volume that
leaks from the volume measurement chamber 2920 between deliveries may be
subtracted out of the total of the residual volume of individual
deliveries so as to prevent confusing an inter-delivery leak with a
partial occlusion. A "leaky" integration, as shown in EQ#187 and EQ#188
may be performed so that the cumulative effect of measurement error may
be minimized. [1030] The Integrator:
[1030] S.sub.var=.gamma..sub.var*S.sub.var+(.nu..sub.res-.nu..sub.interl-
eak) [EQ#187]
[1031] The partial occlusion indicator, .PHI..sub.var, is then set based
on the following logic:
.PHI. va r = { 1 if S v a r
> T va r 0 otherwise [ EQ #188 ]
##EQU00125##
[1032] As with the total occlusion detection and occlusion alarm, a
partial occlusion detection may not trigger an occlusion alarm until a
minimum number of consecutive deliveries are detected/determined to be
occluded. This allows time for partial occlusions to clear through
regular operation of the pump system 2902, which, in some circumstances,
may be accomplished. Additionally, in some embodiments, the partial
occlusion alarm may not be posted unless the total trajectory error
exceeds a certain threshold.
[1033] In some embodiments, the partial occlusion threshold may be a limit
on how much fluid volume may remain in the volume measurement chamber
2920 between deliveries. If there is too much residual volume in the
volume measurement chamber 2920 the pump plunger 2902 may be unable to
deliver a full pump-stroke due to the increased back pressure. In some
embodiments, this sets an upper limit for the allowed residual volume.
Thus, if the maximum target delivery volume for a single delivery is
A.nu..sub.max and the maximum total volume of the volume measurement
chamber 2920 before the pack-pressure prevents further pumping is
V.sub.max then the maximum partial occlusion threshold is:
T.sub.var,max=.DELTA.V.sub.max-.DELTA..nu..sub.max [EQ#189]
[1034] This threshold is on the order of T.sub.var=1.0 .mu.L. If a
cumulative total of more than 1.0 .mu.L of volume remains in the volume
measurement chamber 2920 a partial occlusion may be detected. Again, an
alarm may not be posted unless the under-delivery and number of
consecutive occluded delivery conditions have also been met.
Empty Reservoir Detection
[1035] The empty reservoir detection algorithm, may, in some embodiments,
evaluate the ability of the pump plunger 2902 to deliver fluid from the
reservoir 2918 to the volume measurement chamber 2920. The pump system
2902, in some embodiments, may use two parameters for this evaluation,
which may include, but is not limited to, the pumping error and the total
trajectory error. The pumping error may be the difference between the
target and actual pumped volumes. An internal "empty reservoir
indicator", which may be set if the pump is under-delivering. In some
embodiments, if under-delivery occurs two consecutive deliveries while
the pump plunger 2902 is at its maximum actuation, the maximum target
volume may be decreased, allowing pumping to continue with smaller and
more frequent deliveries. If the maximum target volume is reduced by this
method below a minimum threshold, an empty reservoir alarm may be posted.
Alternatively, in some embodiments, if the difference between the
measured volume delivered and the total target volume requested exceeds a
threshold, an empty reservoir may be assumed by the pump system 2902 and
an alarm may be posted. In some embodiments, empty reservoir alarms may
also be posted due to an up-stream occlusion, leak, or possibly a faulty
pump plunger shape memory actuator 2910.
Maximum Target Volume Reduction Empty Reservoir Alarm
[1036] In some embodiments, as the reservoir 2918 empties, the maximum
volume that the pump chamber 2916 membrane restoring force may pull from
the reservoir 2918 may decrease. Consequently, the maximum volume that
the pump plunger 2902 may deliver to the measurement chamber 2920 and
then to the tubing set 2922 may also decrease. To minimize the volume
left in the reservoir 2918 when the disposable housing assembly may be
discarded, the delivery controller may dynamically decrease the maximum
target volume as this occurs. Thus, in some embodiments, this may allow
the pump system 2900 to continue administering fluid/therapy by
delivering smaller deliveries more frequently.
[1037] The basis for this empty reservoir detection maximum volume
reduction, in some embodiments, may be the difference between the
goal/target volume for each delivery, .nu..sub.target and the volume
pumped into the volume measurement chamber 2920, .nu..sub.pump. This
difference may be defined as the pumped volume error, .nu..sub.error:
.nu..sub.error=.nu..sub.target-.nu..sub.pomp [EQ#190]
[1038] An internal indicator may be set whenever this difference is
greater than zero, .nu..sub.error>0 and the pump plunger 2902 is
either saturating or at its maximum allowed value. If this occurs in two
consecutive deliveries, the maximum target delivery volume may be
decremented and the therapy layer may be called to reschedule the next
delivery. In some embodiments, an exception to this method may be made
during a bolus. When bolusing, the target delivery volume for the entire
bolus may be, in some embodiments, calculated at the start of the bolus.
Therefore, the maximum target volume may not decrement during a bolus.
[1039] In some embodiments, once the maximum target volume has been
reduced to the minimum delivery volume, any further saturated
under-delivering may result in an empty reservoir alarm.
Under Delivery Empty Reservoir Alarm
[1040] In some embodiments, the pump system 2900 may alarm for an empty
reservoir when either the maximum allowed target volume is reduced below
a minimum by way of a dynamic reduction, as described above, or, in some
embodiments, whenever the pump system 2900 is under-delivering by more
than a given amount/threshold. The basis for the under-delivery empty
reservoir detection algorithm may be the difference between the total
target volume, V.sub.target, and the measured volume, V.sub.measured.
This difference may be defined as the total trajectory error,
V.sub.error:
V.sub.error=V.sub.target-V.sub.pumped [EQ#191]
[1041] The under delivery empty reservoir metric therefore may be:
.PHI. empty = { 1 V error > V threshold 0
otherwise [ EQ #192 ] ##EQU00126##
[1042] In some embodiments, additional conditions are not placed on this
metric for alarming. The pump system 2900 may alarm in this way if the
reservoir 2918 is emptying while a bolus is in progress and hence, no
maximum volume reduction may be possible. In some embodiments, the pump
system 2900 may also/rather alarm in this way when the ability of the
pump chamber 2916 is reduced faster than the maximum volume reduction
algorithm may reduce the maximum volume.
Acoustic Leak and Bubble Detection
[1043] In some embodiments of the pump system 2900, the delivery
controller may include an algorithm for detecting acoustic leaks and
resonant air bubbles in the volume measurement chamber 2920. The
detection algorithm may be based on the premise that the volume
measurement sensor damping ratio for the second-order resonance may, in
some embodiments, remain substantially constant during all the
sine-sweeps of an individual delivery.
[1044] In some embodiments, therefore, the comparison of the model fit
calculated damping ratios in the pumped and un-pumped states may be used
as a metric for the detection of, for example, gross acoustic leaks or
large air bubbles. This metric may be separate from the absolute check on
damping ratio performed, in some embodiments, as a volume measurement
sensor level integrity check.
[1045] In some embodiments, the method for detecting acoustic leaks and
bubbles in the volume measurement chamber 2920 may include the following
steps. First, define the maximum and minimum damping ratios from a single
set of sine sweep data:
.zeta..sub.max=max(.zeta..sub.1,.zeta..sub.2,.zeta..sub.3)
.zeta..sub.min=min(.zeta..sub.1,.zeta..sub.2,.zeta..sub.3) [EQ#193]
[1046] The differential damping metric may then be defined as the percent
difference between these two values:
S diffDamp = 100 * .zeta. m i n - .zeta. m
a x .zeta. m i n + .zeta. m a
x [ EQ #194 ] ##EQU00127##
[1047] And the differential damping acoustic leak indicator may be set as
a threshold on this value:
.PHI. diffDamp = { 1 if S diffDamp > T
diffDamp 0 otherwise [ EQ #195 ] ##EQU00128##
[1048] As differentiated from the occlusion and empty reservoir
indicators, described above, a differential damping indicator may be, in
some embodiments, sufficient to trigger an acoustic leak alarm and thus
the differential damping indicator may always, in some embodiments,
result in an acoustic leak alarm.
[1049] The thresholds for this metric may be based entirely on
experimental evidence. In some embodiments, a very conservative threshold
of, e.g., a ten percent difference between the damping ratios of any two
sine sweeps from a single delivery may be set, or T.sub.diffDamp==5.
However, in various embodiments, the threshold may be higher or lower.
Leak Detection
[1050] In some embodiments, the delivery controller may check for leaking
fluid leaking out of the volume measurement chamber 2920 either, for
example, but not limited to, upstream past the measurement valve 2940 or
downstream past the measurement valve 2940. It may be beneficial for many
reasons to perform checks and detect leaks as, for example, leaks may
generate issues both during a delivery and between delivery if residual
volume leaks out of the volume measurement chamber 2920. Thus, in some
embodiments, two different leak tests may be performed by the pump system
2900, including, but not limited to, an inter-delivery leak test to check
for leaks during a delivery and an intra-delivery leak test to check for
loss of residual volume between deliveries.
[1051] The intra-delivery leak test may be performed, in some embodiments,
when the volume measurement chamber 2920 is full of fluid. A first volume
measurement may be taken after the pump plunger 2902 has been actuated.
The fluid may be left in the volume measurement chamber 2920 for a fixed
period of time, e.g., 1 second, and then a second volume measurement may
be taken. In some embodiments, in general, these two volume measurements
should be the same. Thus, any difference between these measurements, that
is, above the expected measurement noise, which, in some embodiments, may
be approximately 1 nL, may generally be attributed to a leaking valve.
The intra-delivery leak test, in some embodiments, may be performed
during each delivery, i.e., each basal or bolus delivery, however, in
various embodiments, the intra-delivery test may be performed more, or
less, often.
[1052] The inter-delivery leak test, in some embodiments, may be performed
when the measurement chamber 2920 is empty except for the normally
generally small amount of residual volume that may persist in the chamber
between deliveries. For the inter-delivery leak test, the last volume
estimate of the previous delivery is compared to the first volume
estimate of the new delivery. As in the case of the intra-delivery leak
test, these measurements should generally be the same. The expected
measurement noise, in some embodiments, may be marginally higher than in
the case of the intra-delivery leak test. Still, any volume change
outside this expected noise floor may also generally be attributed to a
leaking valve. The inter-delivery leak test may be performed before each
basal delivery. In some embodiments, the intra-delivery test may not be
performed during a bolus delivery because there is a minimal delay
between consecutive deliveries. However, in some embodiments, the
intra-delivery test may be performed during a bolus delivery.
Generalized Leak Algorithm
[1053] A similar algorithm may be used to detect both inter and intra
delivery leaks. The basis for the detection algorithms is the leaked
volume defined as the difference between the consecutive volume
estimates:
.nu..sub.leak=.nu..sub.a.nu.s,2-.nu..sub.a.nu.s,1 [EQ#196]
[1054] This leaked volume may be integrated over consecutive deliveries
using a leaky integrator. In this case, the metric for leak detection,
S.sub.leak, will be defined as follows.
S.sub.leak-.gamma..sub.leakS.sub.leak+.nu..sub.leak [EQ#197]
where .gamma..sub.leak<1.0 is the rate of decay. The leak detection
logic is then:
.PHI. leak = { 1 if S leak > T leak 0
otherwise [ EQ #198 ] ##EQU00129##
[1055] In some embodiments, the leak thresholds for the inter-delivery
leak algorithm may be set whereby the measured leaked volume is the
volume that was over-delivered in the case of a leaking measurement
valve. In the case of a leaking measurement chamber inlet valve 2906,
there may be no over-delivery but, in some embodiments, the leak
measurement may not differentiate between this and a measurement valve
leak. In the case of an inter-delivery leak, in some embodiments, the
potential over-delivery will generally be bounded by the amount of
residual volume.
[1056] In some embodiments, the intra-leak detection threshold may be set
by taking into account that the actual leaked volume may be greater than
the volume measured during the leak test. In some embodiments, the leak
test may be performed/completed over a short interval, for example,
approximately 1 second, but where the fluid is pressurized in the volume
measurement chamber 2920 for a longer period of time, this may allow for
additional volume to leak out.
Exit Valve Fail Detection
[1057] In some embodiments, as described above, the pump system 2900
includes a measurement valve 2940 which maintains the fluid in the
measurement chamber 2920 unless and until the measurement has been
completed by the volume measurement sensor. Thus, in some embodiments, it
may be beneficial to determine if a leak is present in the measurement
valve 2940, i.e., where fluid is leaking from the volume measurement
chamber 2920 prior to the completion of the volume measurement, thus,
detecting possibly inaccurate volume measurements as soon as they occur.
The measurement valve 2940 fail detection metric, in some embodiments,
compares the expected outcome of an actuation to the observed outcome. In
the event of a full measurement valve 2940 failure, for example, the
volume pumped may appear to be near zero, as the fluid exits nearly as
fast or as fast as it is pumped into the measurement chamber 2920. Using
a feed forward model estimate for the actuator response, in some
embodiments, measurement valve 2940 failures may be guarded against in
the following manner, where slope, m, and offset, b, are the actuator
model:
v buffer = 3 * v target .delta.
threshold = ( v buffer * m ) + b v threshold
= 0.1 * v target .PHI. noMeasuredVolume = v
pumped < v threshold .PHI.
highControlledEffort = .delta. target > .delta. threshold
.PHI. plungerSaturated = true if the
plunger is saturated Note : both
.delta. threshold and v threshold are
limited to a reasonable range of
values .PHI. exitValveFail = { 1 if .PHI.
noMeasuredVolume and either ( .PHI.
highControllerEffort or .PHI. plungerSaturated )
0 otherwise [ EQ #199 ] ##EQU00130##
[1058] Thus, in some embodiments, following this method, where the
delivery controller commands an actuation that the current model predicts
should result in three times the target volume pumped, but where the
volume observed to be pumped is less than a tenth of the targeted pumped
volume, then in some embodiments, a measurement valve 2940 failure may be
assumed and an alarm may be posted.
[1059] In some embodiments, the intra-leak method assumes that a leak is
continuous. However, discontinuous leaks, i.e., where this assumption
would not hold true, may occur. Thus, in some embodiments, to detect a
leak of this type, the local relationship between the target pump plunger
2902 position commanded and the subsequent volume pumped may be
monitored. An indication of a discontinuous leak may be that a change in
the target position does not necessarily correspond to a change in the
volume pumped. Thus, if the relationship between the target position of
the plunger and the volume pumped becomes uncorrelated, a discontinuous
leak may be suspected by the pump system 2900. Referring now also to FIG.
164, in these cases, in some embodiments, a double pump plunger 2902
stroke delivery may be performed. If the measurement valve 2940 is
operating normally, a second actuation of the pump plunger 2902 would
result in additional volume measured in the measurement chamber 2920.
However, if the measurement valve 2940 performs like a pressure relief
valve, the additional pumped volume is expected to leak discontinuously
and the volume in the measurement chamber 2920 may remain substantially
unchanged. In some embodiments, while performing a discontinuous leak
check, the pump plunger 2902 position change targeted for each of the two
strokes may be one that should, during regular pump system 2900 function,
result in one-half the targeted volume pumped for each stroke, based on
the current actuator model.
[1060] In some embodiments, in addition to the various safety-checks
performed by the command processor 2924, there are a set of secondary
checks performed by the supervisor processor 2926. In some embodiments,
the supervisor processor 2926 may control the power to the pump system
2900 so the active participation of both processors 2924, 2926 is needed
for the pump system 2900 to deliver fluid. The supervisor processor 2926
may provide oversight at a number of different levels and, in some
embodiments, may not turn on power to the pump system 2900 unless all of
the integrity checks pass. Some of the secondary checks performed by the
supervisor processor 2926 may include, but are not limited to, one or
more of the following.
[1061] In some embodiments, a therapy monitor on the supervisor processor
2926 may determine the volume and timing of fluid delivery independent of
the command processor 2924. Thus, in some embodiments, the supervisor
processor 2926 may prevent the command processor 2924 from delivering
fluid if both the timing and volume are not in agreement.
[1062] In some embodiments, the delivery monitor provides oversight of the
volume measurement sensor using a redundant temperature sensor, redundant
storage of the calibration parameter, and independent range-checking of
the results and back-calculation of the volume measurement sensor
model-fit errors.
[1063] In some embodiments, the delivery controller checks for failed
switches (open or closed) and broken SMA, and also guards against
simultaneous or out-of-sequence actuation of the pump plunger 2902 and
measurement valve 2940. The delivery controller may also limit the time
the power is applied to SMA. In some embodiments, the delivery controller
may independently track the target fluid volume and delivered fluid
volume. In some embodiments, the delivery controller may post an alarm
and prevent further delivery if it detects a substantial over or under
delivery.
[1064] Verifying the integrity of a system or device prior to use is
desirable. With respect to medical devices, the integrity of the system
or device may be verified to, for example, but not limited to, ensure the
safety of the user/patient. The detection of fault conditions is at least
one method of verifying the integrity of the system or device. In many
embodiments, detecting fault conditions at start-up is desirable to avoid
downstream errors and failures while the medical device is delivering
therapy or otherwise medically serving a user or patient.
[1065] Some embodiments of the infusion device methods and systems will be
described below with reference to an exemplary embodiment. The exemplary
embodiment is described with respect to a medical infusion pump, which in
some embodiments may be an insulin pump, as shown and described in
herein. Reference herein to a disposable may refer to, in some
embodiments, the various embodiments of the disposable housing assembly
and/or reservoir portion of the infusion pump described herein.
[1066] Although the term "start-up test" may be used herein, the systems
and methods described herein may be used at any time. However, in many
embodiments, the systems and methods are used at start-up as well as at
various other times during the use of the medical device. These include,
but are not limited to, when various faults are detected by the system
during operation. The start-up test may be beneficial for many reasons,
including but not limited to, identifying defective or faulty disposables
prior to their use in administering a medical therapy, and/or detecting a
fault condition with a medical device that is in ongoing use. Thus, the
start-up test may increase the safety of medical devices.
[1067] In some embodiments of the method and system, the method and system
may be used to determine whether a disposable housing assembly has faults
prior to use for delivering therapy. Thus, in some embodiments, the
start-up test/procedure/method may be performed each time a disposable
housing assembly is attached to a reusable housing assembly. The faults
may include, but are not limited to, one or more of the following:
disposable leaks, disposable valve malfunction, disposable reservoir
malfunction, and/or pump/reusable/disposable malfunction. In some
embodiments of the systems and methods, where the integrity of the
disposable is not verified for two sequential disposable housing
assemblies, the lack of integrity of the reusable pump may be
confirmed/assumed. In some embodiments, the system may indicate that a
new pump/reusable may be recommended, and once another reusable is
attached to a disposable, the start-up test may be repeated on a
disposable, which may include, repeating the start-up test on one or more
previously failed disposable housing assemblies. In some embodiments,
this method may be used to consistently verify the integrity of the pump.
[1068] Referring now to FIGS. 165-166, in some embodiments, after a
priming function has been completed, which may be performed for many
reasons, including, but not limited to, initial priming of a new
disposable housing assembly and/or priming after disconnect of a tubing
set 2922 from a cannula. However, in any case, once a priming function
has been completed, and before a cannula is attached to administer
therapeutic medications, the system may, in some embodiments, perform a
verification of the measurement valve 2940 integrity. This may be
completed by actuating the pump plunger 2902 to deliver a threshold
volume of fluid. This may be done by actuating the pump plunger 2902 with
increasingly longer ontime, taking a volume measurements sensor 2946
measurement, and following, determining the volume pumped, and if the
volume pumped is less than a threshold volume, actuating the pump plunger
2902 again using an increasingly longer ontime. However, where the pump
system 2900, after repeating this process, reaches the maximum ontime
(which, in some embodiments, is a preprogrammed time) and has not reached
the threshold volume, i.e., pumped more than the minimum for a
measurement valve 2908, 2940 failure detection but less than the minimum
to pass the start-up test. Thus, in these circumstances, in some
embodiments, the pump system 2900 may conclude that the pump plunger 2902
SMA actuator 2910 and the reservoir may be faulty.
[1069] With respect to measurement valve 2908,2940 integrity, there are
many benefits to confirming the integrity prior to administering therapy
to a user/patient. These benefits include, but are not limited to,
preventing over delivery. Thus, confirming the integrity of the pump
system 2900 prior to administering therapy to a user/patient, safety of
the system may be maintained.
[1070] With respect to the increasing ontime, in various embodiments using
ontime to control the delivery of the medical fluid, this may be
performed to verify a measurement valve 2940 failure versus a pump
plunger 2902/pump plunger SMA actuator 2910 failure. The maximum ontime,
in some embodiments, may be determined using many variables, including,
but not limited to, the ontime that a reasonable pump plunger 2902/pump
plunger SMA actuator 2910 requires to actuate. Thus, where the system is
experiencing the maximum ontime and there is no volume measured by the
volume measurement sensor assembly 2946, i.e., the volume measured is
less than the measurement valve 2908, 2940 failure detection threshold,
than it may be determined and/or confirmed that the measurement valve
2940, 2908 may have failed.
[1071] In some embodiments, however, the pump may be functioning, however,
is weakened. Thus, in some embodiments, this differentiation may be
confirmed by removing the disposable housing assembly, and attaching a
new/another disposable housing assembly. Where the same results are
repeated, it may be determined and/or confirmed that the pump plunger
2902 and/or pump plunger SMA actuator 2910 is weak and may be replaced.
In some embodiments, the controller may recommend the reusable housing
assembly of the pump system 2900 be replaced. In some embodiments, the
controller may include a safety system that prevents the continued use of
the reusable housing assembly that has been determined to be weak, thus,
ensuring the potentially failed reusable housing assembly is not reused.
[1072] Additionally, where the system is confirming whether the pump is
weak or the disposable is faulty, replacing the disposable with a new
disposable may also confirm whether the reservoir 2918 in the first
disposable housing assembly included a faulty reservoir which may
indicate for example, but not limited, one or more of the following: that
the reservoir valve 2904 is not functioning properly, e.g., is not able
to be opened, i.e., is stuck in the closed position, and/or that the
reservoir 2918 is not filled enough. Thus, where a fault is found with
one disposable housing assembly, in some embodiments, the pump system
2900 may require the user/patient to replace the disposable housing
assembly with another disposable housing assembly. In some embodiments,
where a fault is found with the second disposable housing assembly, the
pump system 2900, in some embodiments, may require another reusable
housing assembly. Thus, in some embodiments, this system reduces the need
of the system to determine whether the fault was caused by a leaking
measurement valve 2940 or a faulty reservoir 2910 and/or faulty reservoir
valve 2904. In either case, the reusable housing assembly is replaced.
However, the system and methods described herein ensure that a faulty
reusable housing assembly is detected and confirmed prior to continued
use for providing therapy to a user/patient.
[1073] In some embodiments, when the threshold volume has been met as
determined by the volume measurement sensor assembly 2947, in some
embodiments, a leak test is performed. The threshold volume may be any
volume preprogrammed into the system. In the exemplary embodiment, this
volume may be 1 microliter, however, in other embodiments, the volume may
be less than or greater than 1 microliter. The leak test, in some
embodiments, includes holding the volume of fluid in the volume
measurement chamber 2920 for a predetermined time, e.g., a number of
seconds, which are preprogrammed/predetermined, and in the exemplary
embodiments, may be approximately 2 to 5 seconds, however, in other
embodiments, may be less than or greater than this time. The volume
measurement sensor assembly 2947 then completes another volume
measurement to determine whether any volume leaked from the volume
measurement chamber 2920. Thus, in some embodiments, this leak test may
determine and/or detect a slow leak as opposed to a fast leak (which may
be determined/detected as discussed above).
[1074] In some embodiments, once the leak test is completed, the pump
system 2900 opens the measurement valve 2940 to empty the volume of fluid
from the volume measurement chamber 2920. In some embodiments, the pump
system 2900 may alert the user/patient to shake the volume of fluid off
the tubing set 2922 prior to connection to the cannula.
[1075] Following, in some embodiments, the system confirms the integrity
of the battery, the volume measurement sensor assembly 2946, and the
temperature before signaling to the user/patient that they may connect to
the device, i.e., connecting the tubing set 2922 to the cannula. Thus,
the start-up test presents an opportunity for the pump system 2900 to
perform a delivery, conform the integrity of the disposable housing
assembly and the reusable housing assembly. Additionally, the pump system
executes 2900 all of the standard run-time integrity tests, i.e., the
integrity tests performed after each delivery in the normal course of the
therapy, providing an opportunity to detect other failures before therapy
has started.
[1076] Additionally, in some embodiments, prior to any start-up test, the
pump system 2900 may alert and/or alarm the user/patient of the start-up
test and that the user/patient should ensure they are not connected to
the medical device. In some embodiments, a user interface and/or
controller device (e.g., remote control assembly) may require the
user/patient to verify that they are disconnected, and thus, this may
contribute to increased safety and prevention of inadvertent and/or
accidental over delivery/delivery.
[1077] The start-up test, in some embodiments, may provide an initial data
point for modeling the ontime versus volume delivered (in embodiments
where this system of pump control is used). Thus, in some embodiments,
the final volume pumped into the volume measurement chamber 2920 may be
determined and be used as an initial model data point. From this initial
data point, the slope and offset for the ontime may be determined or
estimated. Thus, although the slope and offset may be adjusted through
the ongoing operation of the pump, the start-up test may present an
initial slope and offset which is a more valuable and useful starting
point for the estimator as compared with no initial data. This may
improve the accuracy of the estimator and the accuracy of the initial
deliveries of the pump. In various embodiments, for example, those
described above and below where an ontime control system is not used, the
start-up procedure and method may be used to provide the initial date
point for the embodiment of the control system.
[1078] In some embodiments, the infusion pump may perform a start-up test
each time the user changes the infusion set/tubing set 2922. In some
embodiments, the start-up test may be performed before the user connects
the infusion set/tubing set 2922 to the cannula. This may be beneficial
for many reasons, including but not limited to, detecting faults before
there is any potential for over or under delivery to the user. Thus, in
some embodiments, the start-up test may have one or more of the following
benefits: detects measurement valve 2940 failures and may update the pump
model to improve the start-up transient. In addition, the start-up method
may also execute all of the standard run-time integrity tests which may
provide an opportunity for the pump system 2900 to detect other failures
before the fluid delivery/therapy has started.
[1079] In the exemplary embodiment, the start-up may accomplish many
tasks, including, but not limited to, initializing the feed forward
actuator model offset, initializing the target measurement valve 2040
position near minimum, and performing pump system 2900 integrity checks.
In practice, the start-up method may be similar to a standard delivery
but with a few key differences outlined in detail below. Referring now to
FIG. 167, a schematic of one embodiment of the start-up test method is
shown. The start-up method may be broken into three distinct phases,
namely, a pumping phase, a leak check phase and a valving phase. The
pumping phase includes collecting data for the pump plunger 2902 modeling
by way of pump SMA actuator 2910 re-actuation. The leak check phase
includes checking pumped volumes against expected values after pumping
fluid into the measurement chamber 2920 and after a delay. The valving
phase includes releasing the pumped fluid from the measurement chamber
2929 and the measurement valve 2908 actuation target position is set by
way of re-actuation of the measurement valve SMA actuator 2908.
[1080] Referring now also to FIGS. 168-170, where the pump plunger 2902
target position is plotted against the volume of fluid pumped to the
volume measurement chamber 2920, during a start-up, the pump plunger 2902
may be re-actuated multiple times without actuation of the measurement
valve 2940. At each re-actuation, the pump plunger 2902 target position
change may be incremented. The size of this increment may vary based on
the total volume that has already been pumped into the volume measurement
chamber 2920 by previous re-actuations.
[1081] Initially, the goal of the start-up procedure is to accurately set
the actuator model offset. In some embodiments, the target position may
be initialized at a value which is low enough to ensure that the pump
will not move fluid. The increment for re-actuation, .delta..sub.1, in
some embodiments, is set at a small value so that when the pump plunger
2902 moves from the dead band into its linear region, the first delivery
will be small. In order to estimate the offset, based on this single
first pumped volume, a default pump slope is assumed. The offset may be
therefore:
.delta..sub.offset=.delta..sub.target-m.sub.default.nu..sub.pumped
[EQ#200]
[1082] Where m.sub.default is the default slope, .delta..sub.target is the
target position change for the first pumped volume delivery, and
.nu..sub.pumped is the first pumped volume. The error in this estimate is
directly proportional to the error in the slope, E, and the size of
.nu..sub.pumped.
e=.delta..sub.offset,calculated-.delta..sub.offset,actual
e=.nu..sub.pumpedm.sub.default-.nu..sub.pumped(m.sub.actual+ )
e=.nu..sub.pumped [EQ#201]
[1083] Referring to FIG. 168, thus, the smaller .nu..sub.pumped is, the
less susceptible the offset calculation is to deviation from the average
slope, m.sub.default, used for the calculation. As such, the pumped
volume limit for this phase, V.sub.1, is close to zero. Once an actuation
has moved any fluid, an accurate offset may be calculated. The offset may
be calculated for every actuation which results in a pumped volume less
than V.sub.1, even those which move no fluid. In the event that no
non-zero volumes are pumped which are less than V.sub.1, the last zero
volume data point is used to determine the offset. This result may be
within .delta..sub.1 of the actual offset.
[1084] Referring now to FIG. 170, after the first non-zero volume has been
pumped and the initial pump offset calculated, the goal of re-actuation,
in some embodiments, is to model the slope of the actuator using the
least squares estimator described above. The increment of position
change, .delta..sub.2, in this phase is set so that multiple points may
be collected for the regression analysis, therefore, improving the model.
[1085] Referring now to FIG. 169, as the volume measurement chamber 2920
fills with fluid, the dynamics of pumping may begin to change. Once a
certain volume, V.sub.2, has been achieved, the pumped volume for a given
pump plunger 2902 position change (i.e., pump plunger 2902 displacement)
may no longer reflect the normal empty chamber actuator response. After
this point, the actuator model may no longer be updated. The third
position change increment for re-actuation, .delta..sub.3, is based on
the normal pump controls described above. The goal of this phase, in some
embodiments, is to fill the volume measurement chamber 2920 to the
minimum hold volume, V.sub.min,startup.
[1086] During the start-up procedure, integrity checks may also be
completed in some embodiments. These may include, but are not limited to,
one or more of the following. For example, if the pump target position
reaches saturation, and the pumped volume remains close to zero, in some
embodiments, the measurement valve 2940 is assumed to have failed in the
open position. As may be determined from inspection, this is slightly
different from the regular delivery for measurement valve 2940 failure
because it is based solely on saturation rather than either saturation or
the pump feed-forward model.
[1087] If the volume delivered to the volume measurement chamber 2920 for
a pre-determined pump plunger 2902 position change, i.e., displacement,
is substantially less than the expected volume, in some embodiments, it
may be determined that the pump is experiencing a "weak pump" fault.
[1088] At the conclusion of the pump plunger 2902 actuation phase of the
start-up test, the total volume pumped into the volume measurement
chamber 2920 is determined. Where the minimum threshold for alarm is not
met, the start-up procedure may conclude that both the measurement valve
2940 and the measurement chamber inlet check valve 2906 are functioning
normally.
[1089] During start-up, the pump system 2900 tests for inter-delivery
leaks using a similar procedure as performed for the run-time tests. In
some embodiments, during the start-up procedure, after fluid has been
pumped to the volume measurement chamber 2920 and a baseline "pumped"
fluid measurement is taken/completed, a second measurement is taken after
a fixed delay. If there is any volume change between these two
measurements (outside the measurement noise), it may be concluded in some
embodiments that it is likely due to fluid leaking past the measurement
valve 2940 and/or the measurement chamber inlet check valve 2906. The
start-up test leak-check procedure, in some embodiments, is the same as
the run-time leak detection, however, the test parameters, e.g., waiting
time between measurements, leak alarm thresholds, may be different.
[1090] In some embodiments, as with the pump plunger 2902, the measurement
valve SMA 2912 is re-actuated multiple times during the start up test. In
some embodiments, following each actuation, the volume in the volume
measurement chamber 2920 may be compared to the volume in the volume
measurement chamber 2920 before the pump plunger 2902 was actuated. In
some embodiments, where there is still a residual volume in the volume
measurement chamber 2920, the measurement valve SMA 2910 may be
re-actuated. In some embodiments, the measurement valve 2940 target
position change may be incremented from its default value with each
re-actuation. When an actuation results in the residual volume dropping
to near zero, the re-actuations may be stopped, and, in some embodiments,
the last targeted measurement valve 2920 position change becomes the new
default position change for future deliveries. In some embodiments, this
may be beneficial for one or more reasons, including, by making the
increment small, a near minimum measurement valve 2920 target position
may be achieved. This may be desirable in some embodiments, for many
reasons, including, but not limited to, it reducing the strain on the
measurement valve SMA 2912 for each actuation, which may potentially
increase the SMA time to failure/shorten the "life" of the SMA.
[1091] In some embodiments, the start-up occlusion detection may be the
same or similar to the run time occlusion detection as described above.
However, in some embodiments, the start-up occlusion detection may not
require the occlusion detection criteria to be met for consecutive
deliveries before alarming. As discussed above, the occlusion detection
criteria is that the volume delivered, as determined by the volume
measurement sensor, is greater than some fraction of the volume pumped.
[1092] In some embodiments, for each measurement valve 2940 re-actuation
of the start-up test, the measurement valve 2940 target position may be
incremented. In some embodiments, when the start-up test is complete, the
last targeted measurement valve 2940 position may become the starting
target measurement valve 2940 position for the first subsequent run time
delivery.
[1093] In some embodiments, rather than the infusion pump system including
a volume measurement sensor assembly, the pump system may include one or
more optical sensors used as a feedback measurement. For example,
referring also to FIGS. 171-172, in some embodiments, rather than a
delivered volume determination from a volume measurement sensor assembly
(see FIGS. 161-162), the volume delivered may be presumed/assumed from at
least one pump plunger 2902 optical sensor input which may be correlated
to a volume delivered based on a model of the pump assembly. In some
embodiments, the pump assembly, which may be integrated into a reusable
housing assembly, may be calibrated at manufacture, and therefore, a
model of pump plunger 2902 displacement versus volume of fluid pumped,
may be generated. In some embodiments, additional modeling may be
completed with respect to disposable housing assemblies, thus, in some
embodiments, each disposable housing assembly may be calibrated with a
reusable housing assembly, and, in some embodiments, each disposable
housing assembly may include, e.g., a calibration code, for example,
which may either be input manually into e.g., a remote control assembly
and/or read by the reusable housing assembly and/or remote control
assembly, for example, using an RFID reader and writer and/or a bar code
scanner. In some embodiments, each reusable housing assembly may include
one or more disposable housing assemblies that have been calibrated with
the reusable housing assembly. In some embodiments, each disposable
housing assembly may be calibrated at manufacture.
[1094] The code, in some embodiments, may indicate the model for the
controller to follow. Thus, variations in disposable housing assemblies
may be input into the controller and pump predictive model; therefore,
the model may be substantially accurate with respect to predicting an
assumed volume delivered.
[1095] However, in some embodiments of the infusion pump system, a series
of one or more models may be established. For example, in some
embodiments, for each disposable housing assembly, a code, or indication
of the model, may be assigned based on a calibration procedure at
manufacture. In these embodiments, therefore, each disposable housing
assembly may not be explicitly calibrated to a specific reusable housing
assembly, however, the calibration procedure may fit the disposable
housing assembly into a category or code that most closely represents the
expected performance based on the calibration procedure.
[1096] Thus, in some embodiments of these embodiments of the infusion pump
system, the displacement of the pump plunger 2902, as discussed above,
may follow a trajectory. The at least one optical sensor may determine
the actual displacement of the pump plunger 2902 and the volume delivered
may be assumed/predicted based on a model. In various embodiments, the
pump plunger 2902 may include one or more optical sensors to determine
the displacement of the pump plunger 2902. Examples of the optical
sensors and the placement of these optical sensors may include those
described above with respect to FIGS. 145-149B
[1097] In some embodiments, variations in the disposable housing assembly,
for example, SMA wire actuation and membrane spring back/return to
starting position following pump, etc., may be accounted for in a
predictive model. Thus, in some embodiments, the number of actuations of
the pump plunger 2902 may translate to a variation in the feed forward
term to compensate for a change in the prediction of the ADC counts to
pump plunger 2902 displacement. In some embodiments, the SMA wire may
vary upon use, and/or the membrane of the pump chamber 2916 may vary upon
use, and therefore, the assumed volume of fluid pumped from the reservoir
2918 for a pump plunge 2902 displacement may vary with the number of pump
actuations. In some embodiments, as the volume in the reservoir is
depleted, the expected volume delivered for ADC count may vary, and
therefore, the volume in the reservoir at the start of the pump may be
factored into the one or more models.
[1098] In some embodiments, the actual displacement of the pump plunge
2902 upon actuation may vary from the trajectory. The volume controller
may feed back the actual pump plunger 2902 displacement information,
sensed by the at least one optical sensor. The difference between the
displacement requested and the actual displacement may be fed into one or
more of the upcoming deliveries, therefore, compensating for a
displacement error.
[1099] Thus, the displacement of the pump plunger 2902 may, in some
embodiments, essentially be translated into an assumed/presumed volume
delivery. Using the at least one optical sensor, the actual displacement
of the pump plunger 2902 for each actuation of the pump plunger 2902 may
be determined. The displacement may be fed back to the target pump
plunger 2902 displacement, and the volume controller may determine
whether and how to compensate for the actual displacement, if determined
necessary. In some embodiments, as discussed above, the pump plunger 2902
displacement, and in some embodiments, taken together with the number of
actuations of the pump plunger 2902 for a given disposable housing
assembly, as well as the reservoir volume, may determine the volume
delivered based on a model.
[1100] In some embodiments, whether and how to compensate for the
determined actual displacement of the pump plunger 2902 may depend on one
or more factors. These may include the size of the difference, whether
the difference may indicate an over delivery or an under delivery, the
number of consecutive actual displacement readings that may show error,
etc. Thus, in some embodiments, a threshold error may be required prior
to the controller adjusting the displacement trajectory.
[1101] In some embodiments of these embodiments of the infusion pump
system, the system may include additional optical sensors to sense the
movement of valves. For example, in some embodiments, the pump system may
include at least one optical sensor to sense the movement of the
reservoir valve 2904 and/or a pump chamber exit valve 2906, which may be
similar to the valves described and shown above, for example, with
respect to FIG. 150. The pump chamber exit valve 2906 may function in a
similar manner to the volume measurement chamber valve 2906, only the
pump chamber exit valve 2906, once opened, may allow fluid to flow from
the pump chamber 2916 to the tubing set 2922. Thus, as discussed above,
in these embodiments, the volume measurement sensor assembly 2946,
together with the measurement valve, may be removed from the pump system
2900.
[1102] Thus, in these embodiments, confirmation of the valves 2904, 2906
opening and closing may confirm fluid was pumped from the reservoir 2918
and fluid was pumped out of the pump chamber 2916 and to the tubing set
2922. Following, where the optical sensors do not sense the opening
and/or closing of one or more valves, the system may post an alarm.
However, as discussed above with respect to various alarms posted to the
system, in some embodiments, the alarms may be posted after a threshold
is met. For example, in some embodiments, an alarm may be posted if the
optical sensor determines that two consecutive pump plunger 2902
actuations occurred and two consecutive errors were detected on one or
more of the valves 2904, 2906.
[1103] As discussed above with respect to the at least one optical sensor
for the pump plunger 2902, in some embodiments, greater than one optical
sensor may be used to collect sensor input from redundant optical
sensors. In some embodiments, for example, as shown in FIG. 147, the two
optical sensors for the pump plunger 2902 may be located in two different
locations in the pump system 2900 thereby collecting sensor data from two
different angles which may provide, in some embodiments, a more developed
determination of the pump plunger 2902 displacement.
[1104] In some embodiments, the two or more optical sensors may be used
for redundancy and also, to determine whether one of the optical sensors
may have an error. Thus, in some embodiments, upon collection of optical
sensor data from two or more optical sensors, the system may, comparing
the two sets of data, determine that one of the sensors may have an error
as the data points vary more than a preset threshold. However, in some
embodiments, where the optical sensor data collected by the at least one
optical sensor is so far away from the expected value, i.e., exceeds one
or more thresholds, the system may post an alarm and conclude the at
least one optical sensor has failed and/or is in error.
[1105] A number of embodiments have been described. Nevertheless, it will
be understood that various modifications may be made. Accordingly, other
embodiments are within the scope of the following claims.
[1106] While the principles of the invention have been described herein,
it is to be understood by those skilled in the art that this description
is made only by way of example and not as a limitation as to the scope of
the invention. Other embodiments are contemplated within the scope of the
present invention in addition to the exemplary embodiments shown and
described herein. Modifications and substitutions by one of ordinary
skill in the art are considered to be within the scope of the present
invention.
* * * * *
