MEMS DOSIMETER

• US 20100171514A1
• Filed: 11/05/2009
• Published: 07/08/2010
• Est. Priority Date: 11/07/2008
• Status: Active Grant

• Current Assignee: Charles Stark Draper Laboratory Incorporated
• Original Assignee: Charles Stark Draper Laboratory Incorporated
• Inventors: Bernstein, Jonathan J.
• Granted Patent: US 8,258,799 B2
• Time in Patent Office: Days
• US Class Current: 324/649
• CPC Class Codes: A61B 2562/028 Microscale sensors, e.g. electromechanical sensors [MEMS]
• CPC Class Codes: F41H 1/02 Armoured or projectile- or missile-resistant garments; Composite protection fabrics F41H5/04 takes precedence
• CPC Class Codes: F41H 1/04 Protection helmets crash helmets A42B3/00
• CPC Class Codes: F42D 5/00 Safety arrangements
• CPC Class Codes: F42D 5/04 Rendering explosive charges harmless, e.g. destroying ammunition F42B39/14 and F42B39/20 take precedence ; extracting primers, dismantling ammunition F42B33/04, F42B33/06 ; chemical deactivating of explosives C06B21/0091; Rendering detonation of explosive charges harmless
• CPC Class Codes: G01L 15/00 Devices or apparatus for measuring two or more fluid pressure values simultaneously
• CPC Class Codes: G01L 5/14 for measuring the force of explosions; for measuring the energy of projectiles
• 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: G01N 27/04 by investigating resistance
• CPC Class Codes: G01P 15/00 Measuring acceleration; Measuring deceleration; Measuring shock, i.e. sudden change of acceleration
• CPC Class Codes: G01P 15/135 by making use of contacts which are actuated by a movable inertial mass
• CPC Class Codes: H01H 1/0036 Switches making use of microelectromechanical systems [MEMS] for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009
• CPC Class Codes: H01H 35/146 operated by plastic deformation or rupture of structurally associated elements
• CPC Class Codes: H01H 35/2657 with different switches operated at substantially different pressures

Abstract

In various embodiments, a dosimeter is employed to passively record a peak pressure (e.g., a peak blast pressure) and/or a maximum acceleration experienced by the dosimeter.

Claims

1. A dosimeter for passively recording a pressure, comprising:

a plurality of breakable structures formed on a chip, at least one structure being breakable at a different pressure level than another structure, and wherein breakage of a subset of the structures is indicative of the pressure experienced by the dosimeter.

2. The dosimeter of claim 1, wherein at least one of the breakable structures is a membrane.

3. The dosimeter of claim 1, wherein at least one of the breakable structures is sized differently from another one of the breakable structures.

4. The dosimeter of claim 1, wherein at least one of the breakable structures comprises a material different from another one of the breakable structures.

5. The dosimeter of claim 1 further comprising a resistor associated with each breakable structure.

6. The dosimeter of claim 5, wherein each resistor crosses over its respective breakable structure.

7. The dosimeter of claim 5, wherein each resistor is embedded in its respective breakable structure.

8. The dosimeter of claim 5, wherein the resistors are wired in parallel.

9. The dosimeter of claim 5, wherein each resistor comprises at least one of silicon or polysilicon.

10. The dosimeter of claim 1, wherein each breakable structure comprises at least one of silicon or polysilicon.

11. The dosimeter of claim 1, wherein one of the breakable structures breaks at a pressure level of approximately 1 kPa.

12. The dosimeter of claim 1, wherein one of the breakable structures breaks at a pressure level of approximately 1.4 MPa.

13. The dosimeter of claim 1, wherein each breakable structure breaks at a pressure level between approximately 1 kPa and 1.4 MPa.

14. The dosimeter of claim 1, wherein each breakable structure is substantially rectangular in shape.

15. The dosimeter of claim 1, wherein each breakable structure has a re-entrant shape that concentrates stress in a pre-determined location.

16. The dosimeter of claim 1, wherein the chip comprises pressure-equalization paths etched therein.

17. The dosimeter of claim 1 further comprising a perforated lid covering the plurality of breakable structures.

18. The dosimeter of claim 17 further comprising a shield coupled to the lid.

19. The dosimeter of claim 1, wherein the chip is packaged without an internal power source.

20. A dosimeter for passively recording an acceleration exposure, comprising:

a plurality of breakable structures formed on a chip, at least one structure being breakable at a different level of acceleration than another structure, each structure comprising an electrically conductive path constrained thereto that is open-circuited upon breakage of the structure, and wherein breakage of a subset of the structures is indicative of the acceleration experienced by the dosimeter.

21. The dosimeter of claim 20, wherein at least one of the breakable structures is a cantilever.

22. The dosimeter of claim 21 further comprising a proof mass coupled to the cantilever.

23. The dosimeter of claim 20, wherein at least one of the breakable structures is sized differently from another one of the breakable structures.

24. The dosimeter of claim 20, wherein at least one of the breakable structures comprises a material different from another one of the breakable structures.

25. The dosimeter of claim 20, wherein each electrically conductive path comprises a resistor.

26. The dosimeter of claim 25, wherein each resistor crosses over its respective breakable structure.

27. The dosimeter of claim 25, wherein each resistor is embedded in its respective breakable structure.

28. The dosimeter of claim 25, wherein the resistors are wired in parallel.

29. The dosimeter of claim 25, wherein each resistor comprises at least one of silicon or polysilicon.

30. The dosimeter of claim 20 wherein each breakable structure comprises at least one of silicon or polysilicon.

31. The dosimeter of claim 20, wherein one of the breakable structures breaks at an acceleration of approximately 2 g.

32. The dosimeter of claim 20, wherein one of the breakable structures breaks at an acceleration of approximately 1000 g.

33. The dosimeter of claim 20, wherein each breakable structure breaks at an acceleration between approximately 2 g and 1000 g.

34. The dosimeter of claim 20, wherein the chip is packaged without an internal power source.

35. A method for determining a pressure, comprising:

measuring a parameter associated with a plurality of interconnected, breakable structures formed on a chip, at least one structure being breakable at a different pressure level than another structure, at least one of the structures having been broken due to the pressure; and

determining the pressure experienced by the chip from the measured parameter.

36. The method of claim 35, wherein the measured parameter is an electrical parameter.

37. The method of claim 36, wherein the electrical parameter is at least one of resistance or capacitance.

38. The method of claim 35, wherein the measured parameter changes upon breakage of each one of the breakable structures.

39. The method of claim 35, wherein one of the breakable structures breaks at a pressure level of approximately 1 kPa.

40. The method of claim 35, wherein one of the breakable structures breaks at a pressure level of approximately 1.4 MPa.

41. The method of claim 35, wherein each breakable structure breaks at a pressure level between approximately 1 kPa and 1.4 MPa.

42. The method of claim 35 further comprising equalizing a pressure on each side of at least one breakable structure without altering the breakable structure'"'"'s sensitivity to rapid pressure changes caused by blasts.

43. The method of claim 35, wherein the chip is packaged without an internal power source.

44. A method for determining an acceleration, comprising:

measuring a parameter associated with a plurality of interconnected, breakable structures formed on a chip, at least one structure being breakable at a different level of acceleration than another structure, each structure comprising an electrically conductive path constrained thereto that is open-circuited upon breakage of the structure, and at least one of the structures having been broken due to the acceleration; and

determining the acceleration experienced by the chip from the measured parameter.

45. The method of claim 44, wherein the measured parameter is an electrical parameter.

46. The method of claim 45, wherein the electrical parameter is at least one of resistance or capacitance.

47. The method of claim 44, wherein the measured parameter changes upon breakage of each one of the breakable structures.

48. The method of claim 44, wherein one of the breakable structures breaks at an acceleration of approximately 2 g.

49. The method of claim 44, wherein one of the breakable structures breaks at an acceleration of approximately 1000 g.

50. The method of claim 44, wherein each breakable structure breaks at an acceleration between approximately 2 g and 1000 g.

51. The method of claim 44, wherein the chip is packaged without an internal power source.