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Miniaturized potassium ion sensor

  • US 4,508,613 A
  • Filed: 12/19/1983
  • Issued: 04/02/1985
  • Est. Priority Date: 12/19/1983
  • Status: Expired due to Fees
First Claim
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1. A chemically sensitive device for monitoring chemical properties, comprising:

  • a semiconductor substrate formed from material being slightly doped toward a first polarity;

    a depletion-mode field-effect transistor on said substrate, said field-effect transistor having source and drain regions oppositely doped with respect to said substrate with a lightly doped gate region thereinbetween also oppositely doped with respect to said substrate;

    a first highly doped region on said substrate of the same polarity of said substrate in electrical contact with said source of said field-effect transistor;

    a reference electrode having a reference membrane on said substrate, said reference electrode providing a first potential to said source through said first highly doped region;

    a chemically sensitive electrode having a chemically sensitive membrane on said substrate, said chemically sensitive membrane having an increased sensitivity to said chemical property to be monitored relative to said reference membrane, said chemically sensitive electrode being electrically connected to said gate to provide a chemically dependent potential to said gate; and

    means for monitoring the current between said source and said drain.

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