RESERVOIR PLUNGER POSITION MONITORING AND MEDICAL DEVICE INCORPORATING SAME

• US 20140058349A1
• Filed: 08/21/2012
• Published: 02/27/2014
• Est. Priority Date: 08/21/2012
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: BAZARGAN, Afshin, VAZQUEZ, Pablo, FONACIER, EJMar, WEAVER, Andrew E.
• Granted Patent: US 8,808,269 B2
• Time in Patent Office: Days
• US Class Current: 604/500
• CPC Class Codes: A61M 2005/16863 Occlusion detection
• CPC Class Codes: A61M 2205/14 Detection of the presence or absence of a tube, a connector or a container in an apparatus
• CPC Class Codes: A61M 2205/3306 Optical measuring means
• CPC Class Codes: A61M 2205/3317 Electromagnetic, inductive or dielectric measuring means
• CPC Class Codes: A61M 2205/332 Force measuring means
• CPC Class Codes: A61M 2205/3365 Rotational speed
• CPC Class Codes: A61M 2205/6054 Magnetic identification systems
• CPC Class Codes: A61M 2205/6063 Optical identification systems
• CPC Class Codes: A61M 2205/6081 Colour codes
• CPC Class Codes: A61M 5/14212 Pumping with an aspiration and an expulsion action
• CPC Class Codes: A61M 5/14248 of the skin patch type
• CPC Class Codes: A61M 5/1456 with a replaceable reservoir comprising a piston rod to be moved into the reservoir, e.g. the piston rod is part of the removable reservoir
• CPC Class Codes: A61M 5/16831 Monitoring, detecting, signalling or eliminating infusion flow anomalies low-level float-valves causing cut-off A61M5/40; indicating or recording presence, absence or direction of flow in general G01P13/0066
• CPC Class Codes: A61M 5/1684 by detecting the amount of infusate remaining, e.g. signalling end of infusion
• CPC Class Codes: A61M 5/1723 using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00

Abstract

Apparatus are provided for infusion devices and related control systems and methods. In one embodiment, an infusion device includes a voided portion adapted to receive a shaft portion that includes a shaft coupled to a plunger of a reservoir. The shaft portion includes a detectable feature, and the infusion device includes a sensing arrangement proximate the voided portion to sense the detectable feature. In some embodiments, a control module is coupled to the sensing arrangement to determine a remaining amount of fluid in the reservoir based at least in part on the sensed position of the detectable feature. In other embodiments, the control module identifies an anomalous condition based at least in part on the sensed position of the detectable feature.

Claims

1. An infusion device, comprising:

a voided portion to receive a shaft portion including a shaft coupled to a plunger of a reservoir, the shaft portion comprising a detectable feature; and

a sensing arrangement proximate the voided portion to sense the detectable feature.

2. The infusion device of claim 1, wherein the shaft includes the detectable feature.

3. The infusion device of claim 2, further comprising a motor having a rotor coupled to the shaft, the shaft being displaced to deliver fluid from the reservoir in response to rotation of the rotor.

4. The infusion device of claim 3, further comprising:

a motor position sensor to measure an amount of rotation of the rotor; and

a control module coupled to the sensing arrangement and the motor position sensor to obtain a measured position of the shaft using the sensing arrangement, determine an expected position of the shaft based on the amount of rotation, and identify an anomalous condition based on a difference between the expected position and the measured position.

5. The infusion device of claim 4, wherein the control module identifies the anomalous condition based on the difference when an axial force aligned with the shaft is less than a threshold value and identifies an occlusion condition based on the difference when the axial force is greater than the threshold value.

6. The infusion device of claim 1, wherein an electrical characteristic of the sensing arrangement is influenced by the detectable feature.

7. The infusion device of claim 6, wherein:

the detectable feature comprises a protruding feature on the shaft; and

the electrical characteristic of the sensing arrangement is influenced by contact with the protruding feature.

8. The infusion device of claim 7, wherein the sensing arrangement comprises a resistive sensing arrangement having a resistance corresponding to a location of a portion of the resistive sensing arrangement in contact with the protruding feature.

9. The infusion device of claim 6, wherein:

the detectable feature comprises a magnetic element producing a magnetic field; and

the sensing arrangement comprises a magnetic sensor having the electrical characteristic influenced by the position of the magnetic field.

10. The infusion device of claim 6, wherein the sensing arrangement comprises a capacitive sensing arrangement having a capacitance influenced by the position of the detectable feature.

11. The infusion device of claim 6, wherein the sensing arrangement comprises an inductive sensing arrangement having an inductance influenced by the position of the detectable feature.

12. The infusion device of claim 6, the detectable feature comprising a protruding feature, wherein the electrical characteristic of the sensing arrangement is influenced by a location of the sensing arrangement in contact with the protruding feature.

13. The infusion device of claim 6, further comprising a control module coupled to the sensing arrangement to detect seating of the reservoir based on the electrical characteristic.

14. The infusion device of claim 1, wherein the sensing arrangement comprises a photodiode to detect the detectable feature.

15. The infusion device of claim 14, wherein:

the sensing arrangement further comprises a radiation source to emit an electromagnetic signal; and

the photodiode detects the electromagnetic signal reflected by the detectable feature.

16. The infusion device of claim 14, the shaft portion including a guide portion encompassing at least a portion of the shaft, wherein the detectable feature is disposed on an interior of the guide portion.

17. The infusion device of claim 1, further comprising a control module coupled to the sensing arrangement to obtain a measured position of the shaft using the sensing arrangement, estimate a remaining amount of fluid in the reservoir based on the measured position, and provide a low fluid notification when the remaining amount is less than a threshold value.

19. The infusion device of claim 1, further comprising a control module coupled to the sensing arrangement to estimate a remaining amount of fluid in the reservoir based at least in part on a position of the detectable feature and provide a low fluid notification when the remaining amount is less than a threshold value.

20. The infusion device of claim 19, further comprising:

a motor having a rotor coupled to the shaft to displace the shaft in response to rotation of the rotor, the plunger being displaced in response to displacement of the shaft to deliver fluid from the reservoir; and

a motor position sensor to measure an amount of rotation of the rotor, wherein the control module is coupled to the motor position sensor to;

determine a shaft position based at least in part on the amount of rotation of the rotor and the position of the detectable feature; and

estimate the remaining amount of fluid based on the shaft position.

21. The infusion device of claim 1, further comprising:

a motor having a rotor coupled to the shaft to displace the shaft in response to rotation of the rotor, the plunger being displaced in response to displacement of the shaft to deliver fluid from the reservoir;

a motor position sensor to measure an amount of rotation of the rotor; and

a control module coupled to the sensing arrangement and the motor position sensor to obtain a measured shaft position based at least in part on a position of the detectable feature, determine an expected shaft position based on the amount of rotation, and identify an anomalous condition based at least in part on a difference between the expected shaft position and the measured shaft position.

22. The infusion device of claim 21, wherein the control module identifies the anomalous condition when the difference exceeds a threshold amount and an axial force aligned with the shaft is less than a threshold value and identifies an occlusion condition when the difference exceeds the threshold amount and the axial force is greater than the threshold value.

24. The infusion device of claim 1, wherein the sensing arrangement comprises a resistive sensing arrangement having a resistance corresponding to a position of the detectable feature.

25. The infusion device of claim 1, further comprising a control module coupled to the sensing arrangement to detect seating of the reservoir based on an electrical characteristic of the sensing arrangement, wherein the electrical characteristic is influenced by a position of the detectable feature.

18. (canceled)

23. (canceled)

26-34. -34. (canceled)

35. A method of operating an infusion device to deliver fluid from a reservoir including a plunger coupled to a shaft such that displacement of the shaft results in displacement of the plunger, the infusion device including a sensing arrangement to sense a detectable feature on the shaft, the method comprising:

operating a motor having a rotor coupled to the shaft to displace the shaft in response to rotation of the rotor and deliver fluid from the reservoir;

obtaining a measured shaft position based at least in part on a position of the detectable feature sensed by the sensing arrangement;

determining an expected shaft position based on an amount of rotation of the rotor; and

identifying an anomalous condition when a difference between the expected shaft position and the measured shaft position exceeds a threshold amount.

36. The method of claim 35, further comprising obtaining an axial force aligned with the shaft and exerted on the shaft by the fluid in the reservoir, wherein identifying the anomalous condition comprises:

identifying a drive system anomaly when the axial force is less than a threshold value; and

identifying an occlusion condition when the axial force is greater than the threshold value.

37. The method of claim 35, further comprising:

determining a remaining amount of fluid in the reservoir based on the measured shaft position; and

providing a low fluid notification when the remaining amount is less than a threshold value.

38. The method of claim 35, further comprising obtaining an amount of rotation of the rotor, wherein obtaining the measured shaft position comprises determining the measured shaft position based on the amount of rotation and the position of the detectable feature.

39. The method of claim 38, wherein determining the measured shaft position comprises converting the amount of rotation of the rotor to a shaft displacement based on a relationship between an incremental rotation of the rotor and a corresponding displacement of the shaft.

40. The method of claim 35, further comprising detecting seating of the reservoir based on an electrical characteristic of the sensing arrangement prior to operating the motor.

41. The method of claim 35, wherein determining the expected shaft position comprises converting the amount of rotation of the rotor to an expected shaft displacement based on a relationship between an incremental rotation of the rotor and a corresponding displacement of the shaft.

42. The method of claim 41, wherein determining the expected shaft position further comprises:

obtaining an initial shaft position using the sensing arrangement prior to operating the motor; and

adding the expected shaft displacement to the initial shaft position to obtain the expected shaft position.

43. The method of claim 35, further comprising obtaining an axial force aligned with the shaft, wherein identifying the anomalous condition comprises:

identifying a drive system anomaly when the difference between the expected shaft position and the measured shaft position exceeds the threshold amount and the axial force is less than a second threshold value; and

identifying an occlusion condition when the difference between the expected shaft position and the measured shaft position exceeds the threshold amount and the axial force is greater than the second threshold value.