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High sensitivity integrated micromechanical electrostatic potential sensor

  • US 5,517,123 A
  • Filed: 08/26/1994
  • Issued: 05/14/1996
  • Est. Priority Date: 08/26/1994
  • Status: Expired due to Term
First Claim
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1. An apparatus for sensing electrical potential of an object, the apparatus comprising:

  • a semiconductor substrate,a dielectric layer over said substrate,a conductive layer over said dielectric layer,first and second electrically conductive and substantially stationary plates suspended above said conductive layer, said first and second plates being substantially coplanar in a plane parallel to said conductive layer and charged to first and second bias voltages, respectively,a third electrically conductive plate suspended above said conductive layer in said plane between said first and second plates such that said first, second, and third plates form first and second capacitors, said first plate forming a first electrode of the first capacitor, said second plate forming a first electrode of the second capacitor, and said third plate forming a second electrode of both of said first and second capacitors with said third plate being resiliently suspended such that said third plate is movable in said plane in response to electrostatic force and is biased to a third voltage,a remote electrode, electrically coupled to said conductive layer, for placement at least electrically proximal to the object whose electrical potential is being sensed, andresolving circuitry coupled to said first and second capacitors for detecting movement of said third plate relative to said first and second plates.

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