MEMS SHOCK SENSORS

• US 20080202258A1
• Filed: 02/22/2007
• Published: 08/28/2008
• Est. Priority Date: 02/22/2007
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Xue, Song S., Amin, Nurul, Ryan, Patrick J.
• Granted Patent: US 7,810,373 B2
• Time in Patent Office: Days
• US Class Current: 73/862.625
• CPC Class Codes: G01P 15/06 using members subjected to a permanent deformation
• CPC Class Codes: G01P 15/0891 with indication of predetermined acceleration values G01P15/135 takes precedence
• 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 2001/0042 Bistable switches, i.e. having two stable positions requiring only actuating energy for switching between them, e.g. with snap membrane or by permanent magnet
• CPC Class Codes: H01H 35/14 Switches operated by change of acceleration, e.g. by shock or vibration, inertia switch wherein the liquid constitutes a contact of the switch H01H29/002
• CPC Class Codes: H01H 35/146 operated by plastic deformation or rupture of structurally associated elements
• CPC Class Codes: H01H 9/168 making use of an electromagnetic wave communication

Abstract

A shock sensor comprises a substrate and at least one flexure coupled to the substrate and configured to deflect upon an application of force to the shock sensor sufficient to deflect the flexure. Deflection of the at least one flexure produces a detectable change in an electrical property of the shock sensor. Examples of detectable changes in an electrical property of the shock sensor include an open circuit condition, a closed circuit condition, and a variation in voltage of a piezo-electric detector. In some embodiments, the change in the electrical property of the shock sensor may be remotely read by interrogation of a radio frequency identification transponder positioned on the substrate using a remote radio frequency identification transceiver. The disclosure also relates to a shock sensing system and method of shock detection.

Claims

1. A shock sensor comprising:

a substrate; and

at least one flexure coupled to the substrate and configured to deflect upon an application of force to the shock sensor sufficient to deflect the flexure,

wherein deflection of the at least one flexure produces a detectable change in an electrical property of the shock sensor.

2. The shock sensor of claim 1, wherein the detectable change in the electrical property of the shock sensor comprises an open circuit condition.

3. The shock sensor of claim 1, wherein the detectable change in the electrical property of the shock sensor comprises a closed circuit condition.

4. The shock sensor of claim 1, further comprising a piezo-electric detector, wherein the detectable change in the electrical property of the shock sensor comprises a variation in voltage of the piezo-electric detector.

5. The shock sensor of claim 1, further comprising an electrically conductive member, wherein the at least one flexure comprises a plurality of electrically conductive flexures configured to electrically connect to the electrically conductive member and the force sufficient to deflect is different for at least two of the flexures.

6. The shock sensor of claim 5, wherein each flexure comprises a mass member having a mass, wherein the mass differs for at least two of the flexures.

7. The shock sensor of claim 5, wherein the force is sufficient to break the flexures, wherein the force sufficient to break is different for each flexure.

8. The shock sensor of claim 5, wherein the detectable change in the electrical property of the shock sensor is an open circuit condition.

9. The shock sensor of claim 8, wherein the electrically conductive member comprises a stationary electrode electrically connected to each flexure, such that upon the application of force to the shock sensor, one or more of the flexures electrically disconnect from the stationary electrode to produce the open circuit condition.

10. The shock sensor of claim 9, wherein the flexures collectively comprise a first set of flexures, the shock sensor further comprising a second set of electrically conductive flexures, wherein the electrically conductive member comprises a first stationary electrode and a second stationary electrode, the first set of flexures being electrically connected to the first stationary electrode and the second set of flexures being electrically connected to the second stationary electrode.

11. The shock sensor of claim 5, wherein the flexures collectively comprise a first set of flexures and the electrically conductive member comprises a second set of electrically conductive flexures each electrically coupled to at least one flexure of the first set, wherein each flexure of the first set is configured to electrically disconnect from the respective flexures of the second set upon the application of force sufficient to deflect the flexure.

12. The shock sensor of claim 11, further comprising at least two frangible members, each frangible member electrically connecting a flexure of the first set to a flexure of the second set, wherein each frangible member is configured to break upon the application of force to the shock sensor, wherein the force sufficient to break each frangible member is different for at least two of the frangible members.

13. The shock sensor of claim 5, wherein the detectable change in the electrical property is a closed circuit condition.

14. The shock sensor of claim 13, wherein the flexures collectively comprise a first set of flexures and the electrically conductive member comprises a second set of electrically conductive flexures, wherein upon the application of force sufficient to deflect a flexure of the first set, the flexure of the first set deflects and electrically connects to a flexure of the second set to produce the closed circuit condition.

15. The shock sensor of claim 13, wherein the electrically conductive member comprises a first magnet and each of the flexures comprises a portion of a second magnet configured to magnetically latch to the first magnet.

16. The shock sensor of claim 15, wherein the flexures collectively comprise a first set of electrically conductive flexures and the electrically conductive member comprises a second set of electrically conductive flexures, the flexures of the first and second sets being arranged in an alternating arrangement, such that upon the application of force, the second magnet of the respective flexure magnetically latches onto the first magnet of an adjacent flexure of the second set to complete an electrical connection.

17. The shock sensor of claim 15, wherein the first and second magnets are separable after the first and second magnets magnetically latch.

18. The shock sensor of claim 15, wherein the first and second magnets each comprise a permanent magnet or a soft magnetic material.

19. The shock sensor of claim 5, wherein a cross-sectional area of a cross-section of each flexure is different than at least one other flexure.

20. The shock sensor of claim 1, further comprising a radio frequency identification (RFID) transponder configured to transmit data identifying a number of flexures producing the detectable change in the electrical property to a remote device.

21. The shock sensor of claim 1, further comprising a detector to detect the change in the electrical property of the shock sensor, wherein the detector comprises a control circuit.

22. The shock sensor of claim 1, further comprising:

a mass, where the at least one flexure is configured to deflect toward the mass upon the application of the force sufficient to deflect the flexure; and

a piezo-electric detector electrically coupled to the at least one flexure, wherein the detectable change in the electrical property comprises a detectable variation in voltage of the piezo-electric detector.

23. The shock sensor of claim 22, wherein the piezo-electric detector is configured to contact the mass.

24. The shock sensor of claim 1, further comprising a resonant circuit configured to be activated remotely by a radio frequency transceiver to provide electrical power to the shock sensor.

25. A shock sensor comprising:

an electrically conductive member; and

at least two electrically conductive flexures configured to electrically connect to the electrically conductive member;

a detector; and

an radio frequency identification (RFID) transponder coupled to the detector,

wherein each flexure is configured to produce a electrical circuit condition upon an application of force to the shock sensor, the force being sufficient to deflect the flexure and the force being different for at least two of the flexures, and

wherein the detector is configured to detect the electrical circuit condition and communicate the electrical circuit condition to the RFID transponder.

26. A method comprising:

exposing a shock sensor to a force, the shock sensor comprising at least one flexure configured to deflect upon an application of a sufficient force to the shock sensor, wherein deflection of the at least one flexure produces a change in an electrical property of the shock sensor; and

detecting the electrical property of the shock sensor to determine a magnitude of the force.

27. The method of claim 26, wherein the shock sensor comprises

a mass, the flexure being configured to deflect toward the mass upon an application of the sufficient force to the shock sensor;

and

a piezo-electric detector electrically coupled to the flexure and configured to produce a detectable variation in voltage upon deflection of the flexure, wherein detecting the electrical property comprises detecting the variation in voltage of the piezo-electric detector.

28. The method of claim 26, wherein the shock sensor comprises an electrically conductive member and at least two electrically conductive flexures configured to electrically connect to the electrically conductive member, wherein each flexure is configured to electrically disconnect from the electrically conductive member upon the application of the sufficient force to the shock sensor, wherein the sufficient force to deflect is different for at least two of the flexures, wherein detecting the electrical property of the shock sensor comprises detecting an open circuit condition between the electrically conductive member and at least one of the flexures.

29. The method of claim 26, wherein the shock sensor comprises an electrically conductive member, and the at least one flexure comprises at least two electrically conductive flexures configured to electrically connect to the electrically conductive member, wherein each flexure is configured to electrically connect to the electrically conductive member upon the application of the sufficient force to the shock sensor, wherein the sufficient force to deflect is different for at least two of the flexures, wherein the detecting the electrical property of the shock sensor comprises detecting a closed circuit condition between the electrically conductive member and at least one of the flexures.

30. The method of claim 26, wherein detecting the electrical property of the shock sensor comprises interrogating a radio frequency identification (RFID) transponder.