Angular displacement sensor of compliant material

• US 9,222,764 B2
• Filed: 10/09/2014
• Issued: 12/29/2015
• Est. Priority Date: 08/17/2013
• Status: Active Grant

• Current Assignee: Bend Labs Inc.
• Original Assignee: Bend Labs Inc.
• Inventors: Reese, Shawn P.
• Primary Examiner(s): Assouad, Patrick
• Assistant Examiner(s): RAJAPUTRA, SURESH KS
• Application Number:
  US14/511,073
• Publication Number:
  US 20150054527A1
• Time in Patent Office: 446 Days
• Field of Search: 324/671, 324/658, 324/686
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/0261 Strain gauges
• CPC Class Codes: A61B 5/1071 measuring angles, e.g. using goniometers A61B5/1123 takes precedence
• CPC Class Codes: A61B 5/6801 specially adapted to be attached to or worn on the body surface
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01B 7/22 using change in capacitance
• CPC Class Codes: G01B 7/30 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01L 1/142 using capacitors

Abstract

Disclosed is a sensing device that includes a flexible substrate having an elongated structure extending between a first end and a second end, the elongated structure being compliant material that is flexible and bendable from a linear, non-bent position to multiple bendable positions. The sensing device also includes a first compliant strain sensing element embedded within the compliant material and extending between the first end and the second end along a longitudinal length of the elongated structure. The first compliant strain sensing element includes a second compliant material that is flexible and bendable, where an electrical property of the first compliant strain sensing element changes in proportion to an applied strain on the elongated structure.

Claims

1. A sensor system comprising:

an angular displacement sensor comprising;

an elongated structure extending between a first end and a second end, the elongated structure being compliant material that is flexible and bendable from a linear, non-bent position to multiple bendable positions; and

a first compliant capacitor, wherein the first compliant capacitor comprises a first conductive layer embedded within and extending from the first end to the second end along a longitudinal length of the elongated structure to form a first electrode of the first compliant capacitor, a second conductive layer embedded within and extending from the first end to the second end along the longitudinal length to form a second electrode of the first compliant capacitor, and an elastomer dielectric layer extending between the first conductive layer and the second conductive layer;

a first member coupled to the first end of the angular displacement sensor, the first member defining a first vector corresponding with an axis of the angular displacement sensor when the elongated structure is in the linear, non-bent position; and

a second member coupled to the second end of the angular displacement sensor, the second member defining a second vector corresponding with the axis of the angular displacement sensor, and wherein an angular displacement is determined between the first vector and the second vector within a first plane defined and extending along the longitudinal length and extending orthogonal through a width of the first compliant capacitor.

2. The sensor system of claim 1, further comprising

a circuit coupled to the first compliant capacitor, the circuit to measure a capacitance of the first compliant capacitor to sense bending movement of the elongated structure, and wherein the circuit is configured to determine the angular displacement between the first and the second vector based on the measured capacitance.

3. The sensor system of claim 1, wherein the first member is a first rigid member and the second member is a second rigid member.

4. The sensor system of claim 1, wherein the angular displacement sensor comprises a plurality of compliant capacitors having a width and extending along the longitudinal length of the elongated structure and spaced from the first compliant capacitor in a parallel manner such that a sensitivity of the angular displacement is increased.

5. The sensor system of claim 1, wherein the compliant material of the elongated structure is an elastomer based material.

6. The sensor system of claim 1, wherein the first electrode is formed as an elastomer matrix of a conductive filler embedded in the compliant material, and wherein the compliant material is an elastomer composite.

7. The sensor system of claim 6, wherein the elastomer composite is at least one of a thermoset elastomer or a thermoplastic elastomer, and wherein the conductive filler is at least one carbon nanotubes, carbon nanofibers, nickel nanostrands, or silver nanowires.

8. The sensor system of claim 1, wherein the first member comprises material that at least completely encases, partially encases, is embedded within, or attached to the first end of the angular displacement sensor.