IMPLANTABLE MEDICAL PUMP WITH PRESSURE SENSOR

• US 20110301575A1
• Filed: 06/03/2010
• Published: 12/08/2011
• Est. Priority Date: 06/03/2010
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Miesel, Keith A., Haase, James M., Paidosh, Chris J., Janzig, Darren A., Denison, Timothy J.
• Granted Patent: US 9,737,657 B2
• Time in Patent Office: Days
• US Class Current: 604/891.1
• CPC Class Codes: A61M 2205/3317 Electromagnetic, inductive or dielectric measuring means
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 39/0208 Subcutaneous access sites for injecting or removing fluids transcutaneous access sites A61M39/0247; implantable infusion devices A61M5/14276
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: G01L 15/00 Devices or apparatus for measuring two or more fluid pressure values simultaneously
• CPC Class Codes: G01L 19/0023 for flowthrough systems having a flexible pressure transmitting element
• CPC Class Codes: G01L 19/0069 from the sensor to its support
• CPC Class Codes: G01L 19/086 for remote indication
• CPC Class Codes: G01L 19/143 Two part housings
• CPC Class Codes: G01L 19/148 Details about the circuit board integration, e.g. integrated with the diaphragm surface or encapsulation
• CPC Class Codes: G01L 19/149 of immersion sensor, e.g. where the sensor is immersed in the measuring medium or for in vivo measurements, e.g. by using catheter tips
• CPC Class Codes: G01L 9/0072 using variations in capacitance

Abstract

The disclosure is directed to a pressure sensor of an implantable medical device. The pressure sensor may utilize detect fluid pressure based on a changing capacitance between two capacitive elements. The pressure sensor may define at least a portion of a fluid enclosure of the IMD. In one example, the pressure sensor has a self-aligning housing shape that occludes an opening in the pump bulkhead of the IMD. An operative surface of the pressure and the portion of the fluid enclosure may be formed of a corrosion resistant and/or biocompatible material. A first capacitive element of the pressure sensor may be a metal alloy diaphragm that deflects in response to external fluid pressure. A second capacitive element of the pressure sensor may be a metal coating on a rigid insulator sealed from the fluid by the diaphragm and a housing of the sensor.

Claims

1. An implantable medical device (IMD) comprising:

a fluid enclosure wall partially defining a fluid enclosure configured to accommodate a fluid within the IMD; and

a pressure sensor comprising an operative surface configured to partially define the fluid enclosure and occlude a channel opening defined by the fluid enclosure wall.

2. The IMD of claim 1, wherein the operative surface comprises:

a sensor housing configured to attach to the portion of the fluid enclosure wall defining the channel opening.

3. The IMD of claim 2, wherein the operative surface further comprises:

a diaphragm mounted to the sensor housing and configured to deflect in response to a pressure of the fluid.

4. The IMD of claim 1, wherein the pressure sensor is sized and shaped to self-align to the channel opening defined by the fluid enclosure wall.

5. The IMD of claim 4, wherein the pressure sensor is configured to self-align to the channel opening such that an electrical connection is made between the pressure sensor and at least one electrical component of the IMD by positioning at least one electrical contact of the pressure sensor in proximity to at least one electrical contact of the at least one electrical component of the IMD.

6. The IMD of claim 1, wherein the fluid enclosure wall is defined in at least a portion of a bulkhead that houses at least one electrical component of the IMD.

7. The IMD of claim 1, wherein the fluid enclosure is a fluid channel configured to direct fluid flow through the IMD.

8. The IMD of claim 1, wherein the fluid enclosure is a reservoir that retains the fluid.

9. The IMD of claim 1, wherein the fluid enclosure is a portion of a receptacle for receiving fluid within the IMD.

10. The IMD of claim 1, wherein the fluid enclosure directs fluid from a medical pump to a catheter outlet.

11. The IMD of claim 1, wherein a surface of the fluid enclosure wall in contact with the fluid and the operative surface of the pressure sensor are formed of a corrosion resistant material.

12. The IMD of claim 11, wherein the surface of the fluid enclosure wall in contact with the fluid and the operative surface of the pressure sensor are formed of a bio-compatible material.

13. The IMD of claim 1, wherein a surface of the fluid enclosure wall in contact with the fluid and the operative surface of the pressure sensor are formed of Grade 9 titanium alloy.

14. The IMD of claim 1, wherein:

the pressure sensor is a capacitive pressure sensor;

the pressure sensor comprises a diaphragm configured as a first capacitive plate of the capacitive pressure sensor and a portion of the operative surface; and

the pressure sensor comprises a metal film configured as a second capacitive plate of the capacitive pressure sensor.

15. The IMD of claim 14, wherein the metal film configured as a second capacitive plate of the capacitive pressure sensor is arranged to be substantially rigid.

16. The IMD of claim 15, wherein the metal film is formed upon a substantially rigid insulator.

17. A method comprising:

accommodating a fluid within a fluid enclosure of an implantable medical device (IMD), wherein the fluid enclosure is partially defined by a fluid enclosure wall;

detecting a pressure of the fluid with a pressure sensor comprising an operative surface configured to partially define the fluid enclosure and occlude a channel opening defined by the fluid enclosure wall.

18. The method of claim 17, wherein detecting the pressure of the fluid includes detecting the pressure with the operative surface that includes a sensor housing configured to be secured to the opening defined by the fluid enclosure wall.

19. The method of claim 18, wherein detecting the pressure of the fluid comprises detecting the pressure with an operative surface that includes a diaphragm mounted to the sensor housing and configured to deflect in response to the pressure of the fluid.

20. The method of claim 17, further comprising:

occluding the channel opening defined by the fluid enclosure wall with the pressure sensor according to a self-aligning shape of the pressure sensor.

21. The method of claim 17, wherein detecting the pressure of the fluid comprises detecting the pressure of the fluid accommodated within a reservoir of the IMD.

22. The method of claim 17, wherein detecting the pressure of the fluid comprises detecting the pressure of the fluid accommodated within a portion of a receptacle for receiving fluid within the IMD.

23. The method of claim 17, wherein detecting the pressure of the fluid comprises detecting the pressure of the fluid accommodated within a fluid conduit of the IMD.

24. The method of claim 17, wherein detecting the pressure of the fluid comprises measuring a change in capacitance between a first capacitive plate and a second capacitive plate of the pressure sensor.

25. A device comprising:

a bulkhead that defines a first portion of a fluid enclosure configured to accommodate a fluid; and

a pressure sensor configured to self-align in a predetermined orientation within a channel opening defined by the bulkhead and occlude the fluid enclosure opening.

26. A pressure sensor comprising:

a titanium diaphragm configured as a first capacitive plate of a capacitor;

a rigid insulator; and

a metal coating on the rigid insulator configured as a second capacitive plate of the capacitor, wherein a distance between the titanium diaphragm and the metal coating is representative of an external pressure exerted upon the titanium diaphragm.

27. The pressure sensor of claim 26, wherein the titanium diaphragm is a portion of an external surface of the pressure sensor configured to contact fluid.

28. The pressure sensor of claim 26, wherein the rigid insulator is secured in a desired position within a cylindrical housing ferrule of the pressure sensor;

and

the titanium diaphragm is affixed to an edge of the cylindrical housing ferrule to enclose an end of the cylindrical housing ferrule.

29. The pressure sensor of claim 26, wherein a distance between the titanium diaphragm and the metal coating is approximately between 0.01 mm and 0.25 mm.

30. The pressure sensor of claim 26, wherein a distance between the titanium diaphragm and the metal coating is approximately 0.08 mm.

31. The pressure sensor of claim 26, wherein the metal coating is one of a braze or a sputter coating.

32. The pressure sensor of claim 26, wherein the metal coating is formed of one or more materials selected from the group consisting of:

gold, titanium, copper, niobium, nickel, aluminum, molybdenum, silver, and their alloys.

33. The pressure sensor of claim 26, wherein the rigid insulator is formed of a ceramic material.

34. The pressure sensor of claim 26, wherein the rigid insulator is substantially rigid to maintain the metal coating in a desired reference plane with respect to the titanium diaphragm.

35. The pressure sensor of claim 26, wherein the rigid insulator prevents over deflection of the titanium diaphragm.

36. The pressure sensor of claim 26, further comprising:

an electrically conductive feedthrough pin disposed through the rigid insulator, wherein the feedthrough pin contacts the metal coating.

37. The pressure sensor of claim 26, wherein the feedthrough pin is recessed and contacts the metal coating in a depression within the rigid insulator;

and

wherein the metal coating includes an indent that corresponds to the depression within the rigid insulator.

38. A pressure sensor comprising:

a first capacitive plate of a capacitor;

a second capacitive plate of the capacitor coupled to a rigid insulator;

an electrically conductive feedthrough pin disposed through the rigid insulator and coupled to the second capacitive plate, wherein;

a first end of the feedthrough pin extends from a surface of the rigid insulator;

a second end of the feedthrough pin is recessed from a capacitive surface of the second capacitive plate proximate to the first capacitive plate; and

the second end of the feedthrough pin is coupled to the second capacitive plate.

39. The pressure sensor of claim 38, further comprising:

a depression formed in the rigid insulator, wherein the second end of the feedthrough pin is disposed within the depression.

40. The pressure sensor of claim 39, wherein the second capacitive plate is formed on a planar surface of the rigid insulator and within at least a portion of the depression;

and the second capacitive plate contacts the second end of the feedthrough pin via the depression.

41. The pressure sensor of claim 38, further comprising:

a printed circuit board forming an opening, wherein the first end of the feedthrough pin extends through the opening without contacting the printed circuit board; and

a conductive member that couples the first end of the feedthrough pin to an electrical contact of the printed circuit board, wherein the first end of the feedthrough pin comprises an attachment surface having a larger diameter than a shaft of the feedthrough pin and configured to facilitate coupling with the conductive member.

42. The pressure sensor of claim 38, wherein the second capacitive plate is a braze or a sputter coating on the rigid insulator.

43. The pressure sensor of claim 38, wherein the first conductive plate is a titanium diaphragm that deflects towards the second conductive plate in response to external pressure.