PRESSURE SENSORS AND MEASUREMENT METHODS

• US 20090270711A1
• Filed: 10/13/2006
• Published: 10/29/2009
• Est. Priority Date: 10/14/2005
• Status: Abandoned Application

• Current Assignee: Iop 24, LLC
• Original Assignee: Iop 24, LLC
• Inventors: Jarvin, Stacey, Phillips, Scott
• Application Number:
  US12/090,068
• Publication Number:
  US 20090270711A1
• Time in Patent Office: Days
• US Class Current: 600/402
• CPC Class Codes: A61B 3/16 for measuring intraocular pressure, e.g. tonometers
• CPC Class Codes: A61B 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/6876 Blood vessel
• CPC Class Codes: A61B 5/6884 Clamps or clips

Abstract

A sensor for measuring pressure within anatomical structures has an impulse mechanism for delivering a mechanical impulse to the anatomical structure and a sensing mechanism for monitoring a mechanical response of the anatomical structure to the impulse. The sensor has application in measuring Intra-Ocular Pressure (IOP). The sensor may also be applied for measuring/pressures within other anatomical structures such as the heart or blood vessels. In one embodiment the impulse mechanism comprises a voice coil and the sensing mechanism comprises a piezoelectric film that generates a signal when it is distorted by motion of the anatomical structure.

Claims

1. A sensor for use in the measurement of pressure within an anatomical structure, the sensor comprising an impulse mechanism for delivering a mechanical impulse to the anatomical structure and a sensing mechanism for monitoring a mechanical response of the anatomical structure to the impulse.

2. A sensor according to claim 1 wherein the impulse mechanism comprises a surface to be placed in contact with the anatomical structure and a mechanism for applying an impulse to the surface.

3. A sensor according to claim 2 wherein the surface comprises a surface of a flexible diaphragm.

4. A sensor according to claim 3 wherein the diaphragm is elastic.

5. A sensor according to claim 3 wherein the diaphragm is maintained under tension.

6. A sensor according to claim 5 wherein the diaphragm is formed to have a configuration substantially conforming to a cylindrical surface when undistorted.

7. A sensor according to claim 5 wherein the diaphragm is formed to have a configuration substantially conforming to a spherical surface when undistorted.

8. A sensor according to claim 1 wherein the sensing mechanism comprises a piezoelectric film.

9. A sensor according to claim 1 wherein the sensing mechanism comprises a coil movable in relation to a magnetic field.

10. A sensor according to claim 1 wherein the impulse mechanism comprises a coil disposed in a magnetic field.

11. A sensor according to claim 1 wherein the impulse mechanism comprises a bladder and a conduit connected to deliver a fluid to the bladder.

12. A sensor according to claim 1 wherein the impulse mechanism comprises a piezoelectric bimorph.

13. A sensor according to claim 1 wherein the sensing mechanism is configured to be placed against a human eye for measurement of intraocular pressure.

14. A sensor according to claim 13 comprising a thin ring on the sensor.

15. A sensor according to claim 13 wherein the sensing mechanism has a compliance that is at least comparable to or greater than a typical compliance of the eye.

16. A sensor according to claim 13 in combination with a processing system connected to receive a signal from the sensing mechanism and to determine a pressure within the anatomical structure based at least in part on the signal.

17. A sensor combination according to claim 16 wherein the processing system is adapted to extract from the signal at least one feature and to compute a pressure value based at least in part on the at least one feature.

18. A sensor combination according to claim 17 wherein the mechanical response comprises a surface motion of the anatomical structure.

19. A sensor combination according to claim 18 wherein the processing system is adapted to extract from the signal a feature representing an amplitude of the surface motion of the anatomical structure.

20. A sensor combination according claim 18 wherein the processing system is adapted to extract from the signal a feature representing a characteristic of a decay of the surface motion of the anatomical structure.

21. A sensor combination according to claim 20 wherein the characteristic of the decay comprises a decay time constant.

22. A sensor combination according to claim 18 wherein the processing system is adapted to extract from the signal a feature representing a frequency or period of the surface motion of the anatomical structure.

23. A sensor combination according to claim 16 wherein the processing system is configured to compute an IOP value based at least in part on one or more of an initial amplitude, a vibration frequency and a decay time constant of eye motion resulting from a step impulse of applied force.

24. A sensor combination according to claim 16 wherein the anatomical structure is an eye and the sensor combination comprises a control system configured to cause the impulse mechanism to deliver impulses to the eye at a rate sufficient to observe pulsatile pressure changes.

25. A sensor combination according to claim 24 wherein the control system is configured to cause the device to deliver impulses to the eye at a rate in excess of any of 1 Hz;

5 Hz;

10 Hz;

15 Hz;

25 Hz and 100 Hz.

26. A sensor combination according to claim 16 wherein the sensor and processing system are connected by a connecting link comprising a fluid-delivery tube.

27. A sensor combination according to claim 16 wherein the sensor and processing system are connected by a connecting link comprising a plurality of electrical conductors encased in a flat film.

28. A sensor combination according to claim 16 comprising a mechanism for periodically delivering a fluid to a vicinity of the sensor.

29. A sensor according to claim 1 wherein the impulse mechanism comprises a coil suspended in a magnetic field and the sensor mechanism comprises a piezoelectric film.

30. A method for measuring intraocular pressure, the method comprising:

delivering an impulse to an eye;

monitoring a time-varying mechanical response of the eye to the impulse over a period of time;

computing an IOP value based upon at least one feature of the time-varying mechanical response.

31. A method according to claim 30 wherein the at least one feature comprises an initial amplitude of the mechanical response.

32. A method according to claim 30 wherein the at least one feature comprises a frequency or period of the mechanical response.

33. A method according to claim 30 wherein the at least one feature comprises a characteristic of a decay of the mechanical response.

34. A method according to claim 33 wherein the at least one feature comprises a time constant of the decay of the mechanical response.

35. A method according to claim 30 comprising repeating the method at a rate sufficient to observe pulsatile pressure changes.

36. A method according to claim 30 comprising repeating the method at a rate in excess of any of 1 Hz;

5 Hz;

10 Hz;

15 Hz;

25 Hz and 100 Hz.

37. A method according to claim 30 comprising placing a sensor in contact with the sclera of the eye under or partly under the eyelid.

38. A method according to claim 30 repeated at spaced-apart times over a period in excess of one or more of:

7 hours;

12 hours and 24 hours.

39. A method according to claim 30 comprising automatically supplying hydration to the eye.

40. A method according to claim 30 comprising automatically supplying anaesthetic to the eye.

41. A method according to claim 30 wherein monitoring the time-varying mechanical response of the eye is performed with a sensor held against the eye at least in part by surface tension.

42. A method according to claim 30 wherein monitoring the time-varying mechanical response of the eye is performed with a thin sensor held against the eye at least in part by pressure of an eyelid.

43. A method according to claim 42 wherein the sensor is located in such a position that it does not impair normal vision of the eye.

44. A method for measuring pressure within an anatomical structure the method comprising:

delivering a mechanical impulse to the anatomical structure

monitoring a time-varying mechanical response of the anatomical structure to the impulse over a period of time; and

,

computing a pressure value based upon at least one feature of the time-varying mechanical response.

45. A method according to claim 44 wherein the at least one feature comprises an initial amplitude of the mechanical response.

46. A method according to claim 44 wherein the at least one feature comprises a frequency or period of the mechanical response.

47. A method according to claim 44 wherein the at least one feature comprises a characteristic of a decay of the mechanical response.

48. A method according to claim 47 wherein the at least one feature comprises a time constant of the decay of the mechanical response.

49-51. -51. (canceled)