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Apparatus and methods for measuring the dielectric and geometric properties of materials

  • US 5,223,796 A
  • Filed: 05/28/1991
  • Issued: 06/29/1993
  • Est. Priority Date: 05/28/1991
  • Status: Expired due to Fees
First Claim
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1. A sensor for measuring properties of a material under test, the sensor comprising:

  • an electrode pair comprising a driven electrode and a sensing electrode disposed in proximity to a material under test;

    terminal means for connecting said driven electrode to electrical signal generating means for providing an electrical signal to said driven electrode to generate an electric field which couples to said sensing electrode thereby generating an electrical signal at said sensing electrode;

    terminal means for connecting said sensing electrode to electrical signal receiving means for receiving the signal at said sensing electrode; and

    a shunting electrode to shunt a portion of said electric field away from said sensing electrode, the shunting electrode having a width greater than that of the driven electrode and of the sensing electrode, disposed at a position in external proximity to said electrode pair and in proximity to the material under test, and held at an electrical potential, the position, width, and electrical potential of said shunting electrode selected to vary the coupling of the electric field to the sensing electrode as a function of the properties of the material under test and to permit measurement of properties of the material under test from the signal at the sensing electrode with a sensitivity significantly greater than that possible in the absence of said shunting electrode.

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