Resistive-capacitive deformation sensor

{
  "publication_number": "US11015989B2",
  "country": "US",
  "kind": "B2",
  "title": "Resistive-capacitive deformation sensor",
  "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.",
  "claims": [
    "1. An apparatus comprising: a first strain-gauge element coupled to a substrate and configured to output a first signal indicative of a resistance of the first strain-gauge element, wherein the first signal is measurable across a first terminal and a second terminal of the first strain-gauge element; and a second strain-gauge element coupled to the substrate and configured to output a second signal indicative of a resistance of the second strain-gauge element, wherein the apparatus is configured to output a third signal indicative of a capacitance measurable between a terminal of the first strain-gauge element and a terminal of the second strain-gauge element.",
    "2. The apparatus of claim 1, wherein the first strain-gauge element is on a first portion of the substrate, and wherein the second strain-gauge element is on a second portion of the substrate.",
    "3. The apparatus of claim 2, 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 apparatus of claim 1, wherein: the second strain-gauge element has 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 apparatus of claim 1, wherein the substrate comprises a flexible, electrically-insulating dielectric material.",
    "6. The 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 an applied deformation.",
    "7. The apparatus of claim 1, wherein: the first strain-gauge element is configured to output the first signal in response to a strain applied in a first direction; and the second strain-gauge element is configured to output the second signal in response to a strain applied in a second direction.",
    "8. The apparatus of claim 1, 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.",
    "9. The apparatus of claim 1, further comprising: a deformation analyzer configured to compute a measure of stretch deformation and a measure of flex deformation of the apparatus, based on the first signal from the first strain-gauge element, the second signal from the second strain-gauge element, and the third signal.",
    "10. The apparatus of claim 9, 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.",
    "11. The apparatus of claim 9, 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.",
    "12. A system comprising: one or more deformation sensors, each deformation sensor including: a first strain-gauge element coupled to a substrate and configured to output a first signal indicative of a resistance of the first strain-gauge element, wherein the first signal is measurable across a first terminal and a second terminal of the first strain-gauge element; and a second strain-gauge element coupled to the substrate and configured to output a second signal indicative of a resistance of the second strain-gauge element, wherein the deformation sensor is configured to output a third signal indicative of a capacitance measurable between a terminal of the first strain-gauge element and a terminal of the second strain-gauge element.",
    "13. The system of claim 12, 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 an applied deformation.",
    "14. The system of claim 13, further comprising: a deformation analyzer configured to compute a measure of stretch deformation and a measure of flex deformation of the system, 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.",
    "15. The system of claim 12, wherein: each of the first and second strain-gauge elements of the deformation sensor has a horse-shoe shape comprising an arcuate head and a pair of elongate leads extending from ends of the arcuate head; and the shapes are configured to circumscribe an articulating joint, a movement of the articulating joint resulting in a corresponding deformation of the deformation sensor.",
    "16. The system of claim 12, wherein the one or more deformation sensors are included in a wearable device.",
    "17. The system of claim 12, wherein the one or more deformation sensors are included in a finger of a glove.",
    "18. The system of claim 12, wherein the one or more deformation sensors comprise a plurality of deformation sensors, each included in a different finger of a glove.",
    "19. A method comprising: measuring a first signal indicative of a resistance of a first strain-gauge element coupled to a substrate, wherein the first signal is measured across a first terminal and a second terminal of the first strain-gauge element; measuring a second signal indicative of a resistance of a second strain-gauge element coupled to the substrate; and measuring a third signal indicative of a capacitance measurable between a terminal of the first strain-gauge element and a terminal of the second strain-gauge element.",
    "20. The method of claim 19, further comprising: computing a measure of stretch deformation and a measure of flex 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 measured third signal."
  ],
  "description_excerpt": "Strain sensors measure strain resulting from applied deformations based on a change in an electrical characteristic (e.g., a resistance, an inductance, or a capacitance) of electrical elements (such as resistive strain gauges, capacitive sensors, or inductive sensors) formed therein. However, strain sensors that measure an individual electrical characteristic (e.g., a resistance change or a capacitance change) resulting from applied deformations in isolation lack the ability to discern and differentiate different types of deformations. As one example, a resistive strain-gauge lacks the ability to disambiguate a stretching deformation from a bending deformation.\n\nA 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.\n\nIn one or more embodiments, the deformation sensing apparatus comprises two horseshoe-shaped (e.g., U-shaped) resistors each formed on opposing parallel sides of the elastic and dielectric substrate, forming a capacitor therebetween. Using sensed resistances from each of the two resistors in combination with the measured capacitance therebetween, the sensor provides three signals that can be used to discriminate between different types of applied deformations.",
  "cpc": [
    "G01L 1/142",
    "G01B 7/18",
    "G01B 7/22",
    "G01D 21/02",
    "G01L 1/14",
    "G01L 1/20",
    "G01L 1/22",
    "G01L 15/00",
    "G01L 5/165"
  ],
  "ipc": [
    "G01L 5/16",
    "G01B 7/16",
    "G01L 1/14",
    "G01L 1/22",
    "G01L 5/165"
  ],
  "assignees": [
    "Facebook Technologies LLC"
  ],
  "inventors": [
    "Sean Jason Keller",
    "Tristan Thomas Trutna",
    "David R. Perek",
    "Bruce A. Cleary, III"
  ],
  "filing_date": "2019-10-31",
  "publication_date": "2021-05-25",
  "grant_date": "2021-05-25",
  "priority_date": "2015-09-02",
  "application_number": "US-201916671000-A",
  "family_id": "58103508",
  "cited_by_count": 3,
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