Microelectromechanical systems contact stress sensor

• US 20060107752A1
• Filed: 06/01/2005
• Published: 05/25/2006
• Est. Priority Date: 11/17/2004
• Status: Active Grant

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Kotovsky, Jack
• Granted Patent: US 7,311,009 B2
• Time in Patent Office: Days
• US Class Current: 73/777
• CPC Class Codes: G01L 1/18 using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material

Abstract

A microelectromechanical systems stress sensor comprising a microelectromechanical systems silicon body. A recess is formed in the silicon body. A silicon element extends into the recess. The silicon element has limited freedom of movement within the recess. An electrical circuit in the silicon element includes a piezoresistor material that allows for sensing changes in resistance that is proportional to bending of the silicon element.

Claims

1. A microelectromechanical systems stress sensor, comprising:

a microelectromechanical systems body, a recess in said body,

a silicon element that extends into said recess, said silicon element having limited freedom of movement within said recess, and

an electrical circuit in said silicon element, said electrical circuit including a piezoresistor material.

2. The stress sensor of claim 1 wherein said silicon member is a silicon beam.

3. The stress sensor of claim 1 wherein said silicon member is a silicon diaphragm.

4. The stress sensor of claim 1 wherein said microelectromechanical systems body comprises a silicon body.

5. The stress sensor of claim 1 wherein said microelectromechanical systems body comprises a compliant material body.

6. The stress sensor of claim 1 wherein said microelectromechanical systems body comprises a silicone body.

7. The stress sensor of claim 1 wherein said microelectromechanical systems body comprises a silicone rubber body.

8. The stress sensor of claim 1 wherein said microelectromechanical systems body comprises a body made of fabric.

9. The stress sensor of claim 1 wherein said recess is an indentation in said microelectromechanical systems body.

10. The stress sensor of claim 1 wherein said recess is an indentation in said microelectromechanical systems body with said indentation having a floor.

11. The stress sensor of claim 1 wherein said recess is a hole that extends through said microelectromechanical systems body.

12. The stress sensor of claim 1 wherein said recess is a grove in said microelectromechanical systems body.

13. The stress sensor of claim 1 wherein said microelectromechanical systems body has a thickness, wherein said silicon element has a thickness, and wherein said thickness of said silicon element is less than said thickness of said microelectromechanical systems body.

14. The stress sensor of claim 1 wherein said electrical circuit comprises a piezoresistor material that extends along said silicon element.

15. The stress sensor of claim 1 wherein said electrical circuit includes legs comprised of a piezoresistor material that extend along said silicon element.

16. The stress sensor of claim 1 wherein said electrical circuit comprises a piezoresistor material that allows for sensing changes in resistance that is proportional to bending of said silicon element.

17. The stress sensor of claim 1 including a material encapsulating said microelectromechanical systems body.

18. The stress sensor of claim 1 including a polyimide film encapsulating said microelectromechanical systems body.

19. The stress sensor of claim 1 including a measuring unit for measuring changes in electrical property of said silicon element.

20. The stress sensor of claim 1 including at least one additional recess in said body, at least one additional silicon element that extends into said additional recess, and at least one additional electrical circuit in said additional silicon element, said additional electrical circuit including a piezoresistor material.

21. The stress sensor of claim 1 including at least one additional recess in said body, at least one additional silicon element that extends into said additional recess, at least one additional electrical circuit in said additional silicon element, said additional electrical circuit including a piezoresistor material, and at least one spring element connecting said silicon element and said additional silicon element.

22. The stress sensor of claim 1 wherein said microelectromechanical systems body comprises a compliant material body and including at least one additional recess in said body, at least one additional silicon element that extends into said additional recess, at least one additional electrical circuit in said additional silicon element, said additional electrical circuit including a piezoresistor material, and at least one flexible element connecting said silicon element and said additional silicon element in a flexible and extensible manner to allow conformity to complex or compliant surfaces.

23. A stress sensor, comprising:

microelectromechanical systems body means for providing a base,

recess means in said body means for forming an open area,

silicon element means that extends into said recess means for limited movement, and

electrical circuit means in said silicon element means for sensing movement of said silicon element means.

24. The stress sensor of claim 23 wherein said silicon element means is a silicon beam.

25. The stress sensor of claim 23 wherein said silicon element means is a silicon diaphragm.

26. The stress sensor of claim 23 wherein said microelectromechanical systems body means comprises a silicon body.

27. The stress sensor of claim 23 wherein said microelectromechanical systems body means comprises a compliant material body.

28. The stress sensor of claim 23 wherein said microelectromechanical systems body means comprises a silicone body.

29. The stress sensor of claim 23 wherein said microelectromechanical systems body means comprises a silicone rubber body.

30. The stress sensor of claim 23 wherein said microelectromechanical systems body means comprises a body made of fabric.

31. The stress sensor of claim 23 wherein said recess means is an indentation in said microelectromechanical systems body means.

32. The stress sensor of claim 23 wherein said recess means is an indentation in said microelectromechanical systems body with said indentation having a floor.

33. The stress sensor of claim 23 wherein said recess means is a hole that extends through said microelectromechanical systems body means.

34. The stress sensor of claim 23 wherein said recess means is a grove in said microelectromechanical systems body means.

35. The stress sensor of claim 23 wherein said microelectromechanical systems body means has a thickness, wherein said silicon element means has a thickness, and wherein said thickness of said silicon element means is less than said thickness of said microelectromechanical systems body.

36. The stress sensor of claim 23 wherein said electrical circuit means comprises a piezoresistor material that extends along said silicon element means.

37. The stress sensor of claim 23 wherein said electrical circuit means includes legs comprised of a piezoresistor material that extend along said silicon element means.

38. The stress sensor of claim 23 wherein said electrical circuit means comprises a piezoresistor material that allows for sensing changes in resistance that is proportional to bending of said silicon element means.

39. The stress sensor of claim 23 including a material encapsulating said microelectromechanical systems body means.

40. The stress sensor of claim 23 including a polyimide film encapsulating said microelectromechanical systems body means.

41. The stress sensor of claim 23 including a measuring unit for measuring changes in electrical property of said silicon element means.

42. The stress sensor of claim 23 including at least one additional recess means in said microelectromechanical systems body means, at least one additional silicon element means that extends into said additional recess means, and at least one additional electrical circuit means in said additional silicon element means, said additional electrical circuit means including a piezoresistor material.

43. The stress sensor of claim 23 including at least one additional recess means in said microelectromechanical systems body means, at least one additional silicon element means that extends into said additional recess means, at least one additional electrical circuit means in said additional silicon element means, said additional electrical circuit means including a piezoresistor material, and at least one spring element connecting said silicon element means and said additional silicon element means.

44. The stress sensor of claim 23 wherein said microelectromechanical systems body means comprises a compliant material body and including at least one additional recess means in said microelectromechanical systems body means, at least one additional silicon element means that extends into said additional recess means, at least one additional electrical circuit means in said additional silicon element means, said additional electrical circuit means including a piezoresistor material, and at least one flexible element connecting said silicon element means and said additional silicon element means in a flexible and extensible manner to allow conformity to complex or compliant surfaces.

45. A method of producing a stress sensor, comprising the steps of:

microprocessing a silicon body to produce a recess in said silicon body,

microprocessing said silicon body to produce a silicon element that extends into said recess and has a limited freedom of movement within said recess,

providing an electrical circuit including a piezoresistor material operatively connected to said silicon element, and

providing a measuring unit for measuring changes in electrical properties of said electrical circuit.

46. The method of producing a stress sensor of claim 45 wherein said step of microprocessing said silicon body to produce a silicon element that extends into said recess and has a limited freedom of movement within said recess comprises forming a section of said silicon body with a reduced thickness to form said silicon element.

47. The method of producing a stress sensor of claim 45 wherein said step of microprocessing said silicon body to produce a silicon element that extends into said recess and has a limited freedom of movement within said recess comprises forming hole in said silicon body that extends only partially through said silicon body leaving a section of said silicon body with a reduced thickness to form said silicon element.

48. The method of producing a stress sensor of claim 45 including the step of encapsulating said silicon body with a polyimide film.

49. The method of producing a stress sensor of claim 45 including the step of providing additional silicon bodies and connecting said silicon body and said additional silicon bodies with flexible elements.

50. The method of producing a stress sensor of claim 45 including the step of providing additional silicon bodies and connecting said silicon body and said additional silicon bodies with spring elements.

51. The method of producing a stress sensor of claim 45 including the step of positioning said silicon body in a compliant material.

52. The method of producing a stress sensor of claim 45 including the step of positioning said silicon body in a silicone material.

53. The method of producing a stress sensor of claim 45 including the step of positioning said silicon body in a fabric.

54. The method of producing a stress sensor of claim 45 including the steps of positioning said silicon body in a compliant material, providing additional silicon bodies in said compliant material, and connecting said silicon body and said additional silicon bodies with flexible elements.

55. The method of producing a stress sensor of claim 54 wherein said compliant material is silicone.

56. The method of producing a stress sensor of claim 54 wherein said compliant material is fabric.