MEMS dosimeter

• US 9,465,047 B2
• Filed: 07/31/2012
• Issued: 10/11/2016
• 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.
• Primary Examiner(s): He, Amy
• Application Number:
  US13/563,245
• Publication Number:
  US 20120297871A1
• Time in Patent Office: 1,533 Days
• Field of Search: 324/691, 324/525, 738/62, 735/143.3
• US Class Current: 1/1
• 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 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, at least one of the breakable structures sized differently from another one of the breakable structures and each structure comprising an electrically conductive path constrained thereto that is open-circuited upon breakage of the structure, the electrically conductive paths wired in parallel such that a measurement of a total resistance across the plurality of breakable structures is indicative of an acceleration level experienced by the dosimeter, each electrically conductive path including a first contact point and a second contact point, and wherein breakage of a subset of the structures is indicative of the acceleration experienced by the dosimeter; and

a pair of contact pads formed on the chip and connected to the electrically conductive path of each structure through the first contact point and the second contact point such that a first contact pad of the pair of contact pads is connected to the first contact point and a second contact pad of the pair of contact pads is connected to the second contact point.

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

3. The dosimeter of claim 2 further comprising a proof mass coupled to the cantilever.

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, wherein each electrically conductive path comprises a resistor.

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 each resistor comprises at least one of silicon or polysilicon.

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

10. The dosimeter of claim 1, wherein one of the breakable structures breaks at an acceleration of approximately 2 g.

11. The dosimeter of claim 1, wherein one of the breakable structures breaks at an acceleration of approximately 1000 g.

12. The dosimeter of claim 1, wherein each breakable structure breaks at an acceleration between approximately 2 g and 1000 g.

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

14. A method for determining an acceleration, comprising:

measuring at least one of a total resistance and a total capacitance associated with a plurality of interconnected, breakable structures formed on a chip using a first contact pad and a second contact pad, at least one structure being breakable at a different level of acceleration than another structure, at least one of the breakable structures sized differently from another one of the breakable structures and each structure comprising an electrically conductive path constrained thereto that is open-circuited upon breakage of the structure and having a first contact point connected to the first contact pad and a second contact point connected to the second contact pad, and at least one of the structures and the respective electrically conductive path having been broken due to the acceleration; and

determining the acceleration experienced by the chip from the at least one measured total resistance and total capacitance.

15. The method of claim 14, wherein the at least one measured parameter total resistance and total capacitance changes upon breakage of each one of the breakable structures.

16. The method of claim 14, wherein one of the breakable structures breaks at an acceleration of approximately 2 g.

17. The method of claim 14, wherein one of the breakable structures breaks at an acceleration of approximately 1000 g.

18. The method of claim 14, wherein each breakable structure breaks at an acceleration between approximately 2 g and 1000 g.

19. The method of claim 14, wherein the chip is packaged without an internal power source.

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

a chip having a cavity defined therein;

an array of cantilevers formed on the chip, such that at least a portion of each cantilever extends over the cavity of the chip, each cantilever of the array of cantilevers being sized differently and breakable at a different level of acceleration than every other cantilever and each cantilever comprising an electrically conductive path between a pair of contact points that is open-circuited upon breakage of the cantilever, the electrically conductive paths wired in parallel such that a measurement of a total resistance across the array of cantilevers is indicative of an acceleration level experienced by the dosimeter;

a first contact pad formed on the chip and connected to a first contact point of each of the pairs of contact points; and

a second contact pad formed on the chip and connected to a second contact point of each of the pairs of contact points.