Pressure sensors having neutral plane positioned transducers

• US 20050160825A1
• Filed: 12/28/2004
• Published: 07/28/2005
• Est. Priority Date: 12/11/2003
• Status: Active Grant

• Current Assignee: Proteus Digital Health, Inc. (Otsuka Holdings Company Limited)
• Original Assignee: Proteus Biomedical, Inc. (Otsuka Holdings Company Limited)
• Inventors: Zdeblick, Mark, Costello, Benedict James
• Granted Patent: US 7,073,387 B2
• Time in Patent Office: Days
• US Class Current: 73/715
• CPC Class Codes: A61B 2562/02 Details of sensors specially adapted for in-vivo measurements
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36564 controlled by blood pressure
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0055 bonded on a diaphragm
• CPC Class Codes: G01L 9/045 with electric temperature compensating means non electric temperature compensating means G01L19/04
• CPC Class Codes: G01L 9/065 with temperature compensating means non electric temperature compensating means G01L19/04

Abstract

Implantable pressure sensors and methods for making and using the same are provided. A feature of embodiments of the subject pressure sensors is that they are low-drift sensors. The subject sensors find use in a variety of applications.

Claims

1. A pressure sensor structure comprising:

a substrate;

a compliant member mounted on said substrate in a manner such that said compliant member has first and second opposing exposed surfaces, wherein said compliant member is positioned at least proximal to said structure'"'"'s neutral plane; and

at least one strain transducer mounted on a surface of said compliant member.

2. The structure according to claim 1, wherein said structure further comprises an integrated circuit.

3. The structure according to claim 1, wherein said substrate comprises a passage oriented orthogonally to said neutral plane and said compliant member spans said passage.

4. The structure according to claim 3, wherein said passage is a well in said substrate and said first exposed surface of said compliant member bounds an enclosed space in said substrate defined by said well and said first exposed surface.

5. The structure according to claim 3, wherein said passage extends through said substrate.

6. The structure according to claim 1, wherein said structure comprises at least first and second strain transducers mounted on said compliant member.

7. The structure according to claim 6, wherein said first and second strain transducers are piezoresistors.

8. The structure according to claim 7, wherein said piezoresistors are fabricated from a stable gauge material.

9. The structure according to claim 6, wherein said first and second strain transducers are associate with said compliant member so that their outputs respond oppositely to deflection of said compliant member resulting from differential pressure across said compliant member but respond similarly to deformation of the substrate.

10. The structure according to claim 1, wherein said at least one strain transducer is separated from said surface of said compliant member by a spacer.

11. The structure according to claim 1, wherein said structure exhibits a drift of no more than about 1 mmHg/year.

12. The structure according to claim 1, wherein said structure exhibits little or no drift over a period of from about 1 to about 40 years.

13. The structure according to claim 1, wherein said structure has a length along an edge of no more than about 500 μ

m and width of nor more than about 100 μ

m.

14. The structure according to claim 1, wherein said structure has a sensitivity sufficient to measure pressure changes in a volume of about ±

1 mmHg.

15. A system comprising:

a conductive member; and

a pressure sensor structure according to claim 1 operatively coupled to said conductive member.

16. The system according to claim 15, wherein said system comprises a plurality of said physiological pressure sensor structures operatively coupled to said conductive member.

17. The system according to claim 15, wherein said system further comprises an energy source coupled to said conductive member.

18. The system according to claim 15, wherein said system further comprises a processing element for determining pressure changes in a volume in response to output signals from said transducer.

19. The system according to claim 15, wherein said system is configured to be implanted into a patient.

20. The system according to claim 19, wherein said system is configured so that said sensor is positioned on a heart wall upon implantation into a patient.

21. A method for fabricating a pressure-sensor structure, said method comprising:

positioning a layer of a compliant material on a surface of a first substrate;

producing at least one strain transducer on a first surface of said compliant material opposite said substrate to produce a pressure-sensor structure to produce a pressure sensor structure according to claim 1.

22. The method according to claim 21, wherein said method is a microfabrication method.

23. The method according to claim 22, wherein said method comprises a photolithographic method.

24. The method according to claim 21, wherein said method further comprises producing a second substrate layer on said first surface of said compliant member, such that said strain transducer layer is interposed between said compliant member layer and second substrate layer.

25. The method according to claim 24, wherein first and second substrates are configured such that said compliant member is positioned at least proximal to said structure'"'"'s neutral plane.

26. The method according to claim 21, wherein said method further comprises producing a boss member on said first surface of said compliant layer.

27. The method according to claim 21, wherein said method further comprises coupling said structure to a conductive member.

28. A method for detecting a pressure change in a volume, said method comprising:

contacting a pressure sensor structure according to claim 1 with said volume;

obtaining an output signal from said pressure sensor; and

using said output signal to detect a pressure change in said volume.

29. The method according to claim 28, wherein said volume is present in a subject.

30. The method according to claim 29, wherein said subject is a human.

31. The method according to claim 30, wherein said method comprises implanting said sensor structure in said human.

32. The method according to claim 29, wherein said volume is a cardiovascular volume.

33. The method according to claim 32, wherein said cardiovascular volume is a heart chamber.

34. The method according to claim 32, wherein said cardiovascular volume is in an artery.

35. The method according to claim 30, wherein said method is a method of monitoring a condition in a subject.

36. The method according to claim 35, wherein said method comprises monitoring said condition remotely.

37. The method according to claim 35, wherein said condition is a cardiovascular condition.

38. The method according to claim 30, wherein said method is employed in a method of one of:

a) treating a subject for heart failure;

b) performing cardiac resynchronization in a subject;

c) managing arrhythmia in a subject;

d) detecting ischemia in a subject;

e) treating a subject for coronary artery disease;

f) monitoring heart valve function in a subject; and

g) monitoring graft function in a subject.