Implantable sensing device for physiologic parameter measurement

• US 6,968,743 B2
• Filed: 01/22/2002
• Issued: 11/29/2005
• Est. Priority Date: 01/22/2001
• Status: Active Grant

• Current Assignee: UIM Pressure Implant Incorporated
• Original Assignee: Integrated Sensing Systems Incorporated
• Inventors: Najafi, Nader, Rich, Collin A., Zhang, Yafan
• Primary Examiner(s): OEN, WILLIAM L
• Application Number:
  US10/054,331
• Publication Number:
  US 20020115920A1
• Time in Patent Office: 1,407 Days
• Field of Search: 737/08, 737/14, 73715-727, 737/56, 338/3, 338/4, 3612831-2834, 600/22, 600/25
• US Class Current: 73/724
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/027 using catheters
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61B 5/6852 Catheters
• CPC Class Codes: A61B 5/6862 Stents
• CPC Class Codes: A61B 5/6876 Blood vessel
• CPC Class Codes: A61B 5/6882 Anchoring means

Abstract

The present invention defines an implantable microfabricated sensor device for measuring a physiologic parameter of interest within a patient. The sensor device includes a substrate and a sensor, integrally formed with the substrate, that is responsive to the physiologic parameter of interest. At least one conductive path is integrally formed with said substrate and coupled to the sensor. Connected to the conductive path is an active circuit. The active circuit is further electrically connected to the sensor.

Claims

1. An implantable microfabricated sensing device capable of being entirely implanted within a human body for measuring a physiologic parameter of said human body, said sensing device comprising a biocompatible monolithic structure comprising:

a substrate;

a sensor integrally microfabricated with said substrate and being responsive to the physiologic parameter;

at least one conductive path integrally formed with said substrate and said sensor; and

active circuitry microfabricated in proximity to said sensor and electrically connected to said sensor by said conductive path.

2. The sensing device of claim 1 wherein said sensor is a capacitive sensor having a fixed electrode and a moveable electrode.

3. The sensing device of claim 1 wherein said sensor comprises a cap layer on said substrate.

4. The sensing device of claim 3 wherein said cap layer includes positions defining a diaphragm of said sensor.

5. The sensing device of claim 3 wherein said active circuitry is integrally fabricated in said substrate.

6. The sensing device of claim 3 wherein said cap layer is formed of monocrystalline silicon.

7. The sensing device of claim 3 wherein said cap layer is boron doped silicon.

8. The sensing device of claim 2 wherein said fixed and moveable electrodes define an interior volume therebetween and a surface activity in said substrate defines a displacement cavity in communication with said interior volume.

9. The sensing device of claim 2 wherein said fixed electrode includes a main electrode and at least one reference electrode.

10. The sensing device of claim 1 wherein said sensing device is entirely implanted within said human body and is operating to measure the physiologic parameter within said human body.

11. The sensing device of claim 1 further comprising a cap layer formed over said substrate.

12. The sensing device of claim 11 wherein said cap layer includes a portion defining a moveable electrode of said sensor.

13. The sensing device of claim 11 wherein said cap layer is conductive.

14. The sensing device of claim 12 wherein said cap layer is doped silicon.

15. The sensing device of claim 1 wherein said sensor is a pressure sensor.

16. The sensing device of claim 1 wherein said sensor is a temperature sensor.

17. The sensing device of claim 1 wherein said sensor is a chemical sensor.

18. The sensing device of claim 1 further comprising a cap layer bonded to said substrate, said active circuitry being integrally formed in said cap layer.

19. The sensing device of claim 1 wherein said active circuitry is integrally formed in said substrate.

20. The sensing device of claim 1 wherein said active circuitry is mounted to said substrate.

21. The sensing device of claim 20 wherein said active circuitry is received within a recess defined in said substrate.

22. The sensing device of claim 1 further comprising at least two sensors.

23. The sensing device of claim 22 wherein said two sensors sense the same physiologic parameter.

24. The sensing device of claim 22 wherein said two sensors sense different physiologic parameters.

25. The sensing device of claim 1 wherein said sensor is a capacitive sensor having a fixed electrode and a moveable electrode, said fixed and moveable electrodes being electrically coupled by first and second conductive paths to said active circuitry, said first and second paths being electrically isolated from one another.

26. The sensing device of claim 25 wherein said paths are isolated by a dielectric layer therebetween.

27. The sensing device of claim 25 wherein said paths are isolated by a p-n junction structure.

28. The sensing device of claim 25 wherein said sensor operates in a proximity mode whereby the fixed electrode and the moveable electrode do not contact each other when responding to the physiologic parameter.

29. The sensing device of claim 25 wherein said sensor operates in a touch mode whereby the fixed electrode and the moveable electrode progressively contact each other when responding to the physiologic parameter.

30. The sensing device of claim 1 further comprising a bioinert coating over a majority of exterior surfaces of said sensor.

31. The sensing device of claim 1 further comprising a housing defining a form factor providing an external shape to said sensing device that differs from the monolithic structure.

32. The sensing device of claim 31 wherein said housing is of a non-rigid material.

33. The sensing device of claim 31 wherein said housing is a plastic material.

34. The sensing device of claim 31 wherein said housing comprises a recess providing intimate access to the sensor.

35. The sensing device of claim 2 wherein said fixed electrode is a conductive layer on said substrate.