MONITORING THE OPERATING HEALTH OF A FORCE SENSOR IN A FLUID INFUSION DEVICE

• US 20120165780A1
• Filed: 12/22/2010
• Published: 06/28/2012
• Est. Priority Date: 12/22/2010
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: BAZARGAN, Afshin, VAZQUEZ, Pablo, KOW, Hsiao-Yu S., MONIRABBASI, Salman, Hanson, Ian B.
• Granted Patent: US 8,628,510 B2
• Time in Patent Office: Days
• US Class Current: 604/500
• CPC Class Codes: A61M 2005/16863 Occlusion detection
• CPC Class Codes: A61M 2205/332 Force measuring means
• CPC Class Codes: A61M 5/00 Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests vaccination appliances for veterinary use A61D1/025 ; tube connectors, tube couplings, valves or branch units specially adapted for medical use A61M39/00; containers specially adapted for medical or pharmaceutical purposes A61J1/00; combinations of vial and syringe for mixing or transferring their contents A61J1/20; holders for containers for collecting, storing or administering blood or medical fluids A61J1/16
• CPC Class Codes: A61M 5/14244 adapted to be carried by the patient, e.g. portable on the body
• CPC Class Codes: A61M 5/16854 by monitoring line pressure

Abstract

A device for delivering fluid to a user includes a housing, a drive motor assembly in the housing, a force sensor, and an electronics module. The drive motor assembly regulates delivery of fluid by actuating a piston of a fluid reservoir, and the force sensor generates output levels in response to force imparted thereto during, for example, fluid delivery operations. The electronics module processes the output levels of the force sensor to assess the operating health of the force sensor, to check for occlusions in the fluid delivery path, and to monitor the seating status of the fluid reservoir.

Claims

1. A method of operating a fluid infusion device comprising a drive motor assembly and a force sensor associated with the drive motor assembly, the method comprising:

activating a rewind operation of the drive motor assembly;

determining a rewind force imparted to the force sensor during the rewind operation; and

initiating corrective action for the fluid infusion device when the rewind force is less than a lower threshold force or greater than an upper threshold force.

2. The method of claim 1, wherein initiating corrective action comprises:

initiating a first type of corrective action when the rewind force is less than the lower threshold force; and

initiating a second type of corrective action when the rewind force is greater than the upper threshold force.

3. The method of claim 1, wherein initiating corrective action comprises generating a user alert at the fluid infusion device.

4. The method of claim 1, further comprising:

performing a plurality of calibrating rewind operations;

determining a respective calibration rewind force imparted to the force sensor during each of the calibrating rewind operations, resulting in a plurality of calibration rewind forces;

calculating a nominal rewind force from the plurality of calibration rewind forces;

deriving the lower threshold force and the upper threshold force from the nominal rewind force; and

storing the lower threshold force and the upper threshold force in a memory element of the fluid infusion device.

5. The method of claim 4, further comprising storing the nominal rewind force in the memory element of the fluid infusion device.

6. The method of claim 4, wherein the nominal rewind force is ideally equal to zero pounds.

7. The method of claim 1, further comprising:

completing the rewind operation before placement of a new fluid reservoir into the fluid infusion device; and

using the force sensor to detect when the new fluid reservoir is seated in the fluid infusion device.

8. The method of claim 1, wherein:

the drive motor assembly regulates delivery of fluid by the fluid infusion device via an infusion set; and

the method further comprises using the force sensor to detect an occlusion of the infusion set.

9. The method of claim 1, further comprising:

determining a measure of actuation force imparted to the force sensor during a fluid delivery action of the drive motor assembly;

comparing the measure of actuation force against a range of valid values that represents normally expected measures of actuation forces; and

initiating the corrective action when the measure of actuation force is outside the range of valid values.

10. A device for delivering fluid to a user, the device comprising:

a housing;

a drive motor assembly in the housing to regulate delivery of fluid by actuating a piston of a fluid reservoir;

a force sensor associated with the drive motor assembly to generate output levels in response to force imparted thereto; and

an electronics module coupled to the force sensor to process the output levels to determine operating health of the force sensor.

11. The device of claim 10, wherein the electronics module:

determines a rewind force imparted to the force sensor during a rewind operation; and

initiates corrective action when the rewind force is not within a specified range.

12. The device of claim 11, wherein the electronics module initiates generation of a user alert at the device when the rewind force is not within the specified range.

13. The device of claim 10, further comprising a memory element to store the specified range.

14. The device of claim 10, wherein the force sensor is located between an end of the drive motor assembly and a portion of the housing.

15. A method of operating a fluid infusion device comprising a drive motor assembly and a force sensor associated with the drive motor assembly, the method comprising:

determining a measure of actuation force imparted to the force sensor during a fluid delivery action of the drive motor assembly;

comparing the measure of actuation force against a range of valid values that represents normally expected measures of actuation forces; and

when the measure of actuation force is outside the range of valid values, initiating corrective action for the fluid infusion device.

16. The method of claim 15, wherein initiating corrective action comprises generating a user alert at the fluid infusion device.

17. The method of claim 15, wherein initiating corrective action comprises:

recording an invalid force event for the measure of actuation force; and

analyzing a set of invalid force events to determine a course of action for the fluid infusion device.

18. The method of claim 17, wherein analyzing the set of invalid force events is performed to reduce false alerts associated with operating health of the force sensor.

19. The method of claim 17, further comprising generating a user alert at the fluid infusion device in response to recording at least a threshold number of invalid force events corresponding to consecutive fluid delivery actions of the drive motor assembly.

20. The method of claim 15, further comprising:

activating a rewind operation of the drive motor assembly;

determining a rewind force imparted to the force sensor during the rewind operation; and

initiating the corrective action when the rewind force is less than a lower threshold force or greater than an upper threshold force.