Silicon force sensor and method of using the same

• US 9,459,161 B1
• Filed: 06/01/2016
• Issued: 10/04/2016
• Est. Priority Date: 10/28/2013
• Status: Active Grant

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Galambos, Paul C., Crenshaw, Thomas B., Nishida, Erik E., Burnett, Damon J., Lantz, Jeffrey W.
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): PLUMB, NIGEL H
• Application Number:
  US15/170,355
• Publication Number:
  US 20160273978A1
• Time in Patent Office: 125 Days
• Field of Search: 738/620.45, 738/62
• US Class Current: 1/1
• 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
• CPC Class Codes: G01L 1/26 Auxiliary measures taken, or devices used, in connection with the measurement of force, e.g. for preventing influence of transverse components of force, for preventing overload
• CPC Class Codes: G01L 5/0028 Force sensors associated with force applying means G01L5/0052, G01L5/0057, G01L5/0061 take precedence

Abstract

The various technologies presented herein relate to a sensor for measurement of high forces and/or high load shock rate(s), whereby the sensor utilizes silicon as the sensing element. A plate of Si can have a thinned region formed therein on which can be formed a number of traces operating as a Wheatstone bridge. The brittle Si can be incorporated into a layered structure comprising ductile and/or compliant materials. The sensor can have a washer-like configuration which can be incorporated into a nut and bolt configuration, whereby tightening of the nut and bolt can facilitate application of a compressive preload upon the sensor. Upon application of an impact load on the bolt, the compressive load on the sensor can be reduced (e.g., moves towards zero-load), however the magnitude of the preload can be such that the load on the sensor does not translate to tensile stress being applied to the sensor.

Claims

1. A method, comprising:

applying a compressive preload to a piezoresistive device, wherein the compressive preload is greater in magnitude than an operating range of operational loads;

transmitting an operational load within the operating range to the piezoresistive device so as to produce a reduction in the compressive preload; and

measuring the reduction in the compressive preload to facilitate determining a magnitude of the operational load.

2. The method of claim 1, wherein the compressive preload is applied to the piezoresistive device by tightening of a nut on a boltshaft of a bolt, wherein the bolt is located on a supporting structure to which the operational load is applied.

3. The method of claim 2, wherein a bolthead of the bolt is located in a hole extending from an outer surface of the supporting structure to an inner surface of the supporting structure, and the piezoresistive device is located on the boltshaft between the nut and the inner surface of the supporting structure, the tightening of the nut applying the compressive preload to the piezoresistive device.

4. The method of claim 1, wherein the piezoresistive device is a plate fabricated with a thinned inner region and a thicker outer region, the thinned inner region facilitates inducing strain into a conductive trace element located at the thinned inner region facilitating the measuring of the reduction in compressive preload.

5. The method of claim 1, wherein the piezoresistive device comprising a plate of silicon.

6. A method, comprising:

applying a compressive preload to a piezoresistive device, wherein the compressive preload is greater in magnitude than an operating range of operational loads;

transmitting an operational load within the operating range to the piezoresistive device; and

measuring the reduction in the compressive preload.

7. The method of claim 6, wherein the compressive preload is applied to the piezoresistive device by tightening of a nut on a boltshaft of a bolt, wherein the bolt is located on a supporting structure to which the operational load is applied.

8. The method of claim 7, wherein a bolthead of the bolt is located in a hole extending from an outer surface of the supporting structure to an inner surface of the supporting structure, and the piezoresistive device is located on the boltshaft between the nut and the inner surface of the supporting structure, the tightening of the nut applying the compressive preload to the piezoresistive device.

9. The method of claim 6, wherein the piezoresistive device is a plate fabricated with a thinned inner region and a thicker outer region, the thinned inner region facilitates inducing strain into a conductive trace element located at the thinned inner region facilitating the measuring of the reduction in compressive preload.

10. The method of claim 6, wherein the piezoresistive device comprising a plate of silicon.

11. A method, comprising:

applying a compressive preload to a piezoresistive device, wherein the compressive preload is greater in magnitude than an operating range of operational loads;

transmitting an operational load within the operating range to the piezoresistive device; and

measuring the reduction in the compressive preload to facilitate determining a magnitude of the operational load.

12. The method of claim 11, wherein the compressive preload is applied to the piezoresistive device by tightening of a nut on a boltshaft of a bolt, wherein the bolt is located on a supporting structure to which the operational load is applied.

13. The method of claim 12, wherein a bolthead of the bolt is located in a hole extending from an outer surface of the supporting structure to an inner surface of the supporting structure, and the piezoresistive device is located on the boltshaft between the nut and the inner surface of the supporting structure, the tightening of the nut applying the compressive preload to the piezoresistive device.

14. The method of claim 11, wherein the piezoresistive device is a plate fabricated with a thinned inner region and a thicker outer region, the thinned inner region facilitates inducing strain into a conductive trace element located at the thinned inner region facilitating the measuring of the reduction in compressive preload.

15. The method of claim 11, wherein the piezoresistive device comprising a plate of silicon.