Resistive-capacitive deformation sensor

Patent metadata

Field	Value
Publication number	US-10502643-B2
Application number	US-201816055376-A
Country	US
Kind code	B2
Filing date	Aug 6, 2018
Priority date	Sep 2, 2015
Publication date	Dec 10, 2019
Grant date	Dec 10, 2019

Abstract

A deformation sensing apparatus comprises an elastic substrate, a first strain-gauge element formed on a first surface of the elastic substrate, and configured to output a first signal in response to a strain applied in a first direction, and a second strain-gauge element formed on a second surface of the elastic substrate opposite to the first surface, and configured to output a second signal in response to a strain applied in the same first direction.

First claim

What is claimed is:

1. A deformation sensing apparatus comprising:
a substrate;
a first strain-gauge element coupled to a first portion of the substrate, and configured to output a first signal in response to a strain applied in a first direction; and
a second strain-gauge element coupled to a second portion of the substrate distinct from the first portion, and configured to output a second signal in response to a strain applied in the same first direction, and
wherein the deformation sensing apparatus is further configured to output a third signal responsive to an applied deformation, the third signal being measureable between a terminal of the first strain-gauge element and a terminal of the second strain gauge-element.

2. The deformation sensing apparatus of claim 1 , wherein the first portion of the substrate is opposite to the second portion of the substrate.

3. The deformation sensing apparatus of claim 1 , wherein the first portion of the substrate is a top portion of the substrate and the second portion of the substrate is a bottom portion of the substrate.

4. The deformation sensing apparatus of claim 1 , wherein:
the first strain-gauge element has two distinct terminals, a first terminal and a second terminal;
the first signal is measurable across the first and second terminals of the first strain-gauge element;
the second strain-gauge element has two distinct terminals, a third terminal and a fourth terminal; and
the second signal is measurable across the third and fourth terminals of the second strain-gauge element.

5. The deformation sensing apparatus of claim 1 , wherein the substrate comprises a flexible, electrically-insulating dielectric material.

6. The deformation sensing apparatus of claim 5 , wherein:
each of the first and second strain-gauge elements has a horse-shoe shape comprising an arcuate head and a pair of elongate leads extending from ends of the arcuate head;
alignment of the shapes of the first and second strain-gauge elements correspond along an axis orthogonal to the first portion and the second portion of the substrate;
central axes of the first and second strain-gauge elements are aligned parallel and coplanar to each other along a planes orthogonal to the first portion and the second portion of the substrate; and
corresponding leads of the pairs of elongate leads of the first and second strain-gauge elements are respectively length-wise parallel and have substantially the same dimensions.

7. The deformation sensing apparatus of claim 6 , wherein:
a measurement circuit configured to measure the first signal from the first strain-gauge element and the second signal from the second strain-gauge element in response to an applied deformation; and
a deformation analyzer configured to compute a measure of stretch deformation and a measure of flex deformation of the sensing apparatus, in the applied deformation, based on the measured first signal from the first strain-gauge element, the measured second signal of the second strain-gauge element, and the third signal.

8. The deformation sensing apparatus of claim 7 , wherein:
the measure of stretch deformation is indicative of an average change in lengths in relationship to an undeformed length of the first and second strain gauge elements; and
the measure of flex deformation is indicative of a bend radius of an angular bend of portions of the substrate on which the first and second strain-gauge elements are formed.

9. The deformation sensing apparatus of claim 7 , wherein the deformation analyzer is further configured to determine whether the stretch deformation corresponds to a compression stretch or an elongation stretch, by comparing the measured first, second, and third signals, based on a sign of changes in resistances of the first and second strain gauge elements and a sign of change in capacitance of the substrate.

10. The deformation sensing apparatus of claim 1 , further comprising:
a measurement circuit configured to measure the first signal from the first strain-gauge element and the second signal from the second strain-gauge element in response to the applied deformation; and
a deformation analyzer configured to compute a measure of stretch deformation and a measure of flex deformation of the sensing apparatus, in the applied deformation, based on the measured first signal from the first strain-gauge element, the measured second signal of the second strain-gauge element, and the third signal.

11. The deformation sensing apparatus of claim 10 , wherein:
the first signal is indicative of a first resistance of the first strain-gauge element;
the second signal is indicative of a second resistance of the second strain-gauge element; and
the third signal is indicative of a capacitance across the substrate measured responsive to the applied deformation.

12. The deformation sensing apparatus of claim 11 , wherein the deformation analyzer computes the measure of stretch deformation as a proportion of length change ((ΔL)/L 0 ) of the first and second strain-gauge elements, based on the first, second, and third signals, using the equations:

R
1

=

R
2

=

R
0

+

(

GF
·
Δ

⁢

⁢
L

)

C
=

ℰ
⁢

Area
gap

=

ℰ
=

L
0

·

W
0

g

=

ℰ
⁢

L
0

Assignees

• Facebook Tech Llc

Inventors

• Keller Sean Jason
• Trutna Tristan Thomas
• Perek David R
• Cleary Iii Bruce A

Classifications

• G01D21/02

  Measuring two or more variables by means not covered by a single other subclass · CPC title

• G01B7/18

  using change in resistance · CPC title

• G01L1/142 Primary

  using capacitors · CPC title

• G01L15/00 Primary

  Devices or apparatus for measuring two or more fluid pressure values simultaneously · CPC title

• G01L5/165

  using variations in capacitance · CPC title