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Capacitive humidity sensor

  • US 6,742,387 B2
  • Filed: 11/19/2002
  • Issued: 06/01/2004
  • Est. Priority Date: 11/19/2001
  • Status: Expired due to Fees
First Claim
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1. A capacitive humidity sensor comprising:

  • a substrate (10);

    a pair of opposed electrodes (31, 32), which are formed on a surface of the substrate (10) in the same plane in isolation from each other, wherein the electrodes are each comb-shaped and have teeth, and the teeth of the electrodes have a generally uniform width (L1) and are interdigitated, and the teeth of one of the electrodes are spaced apart from the teeth of the other electrode by a generally uniform separation distance (L2), and the separation distance (L2) is 5 μ

    m when the width (L1) is less than 3 μ

    m, and the separation distance (L2) is less than or equal to 5 μ

    m when the width (L1) is greater than or equal to 3 μ

    m; and

    a humidity-sensitive film (50), the capacitance of which changes with humidity, wherein the humidity-sensitive film covers the electrodes and an area between the electrodes, and humidity is detected based on changes in the capacitance between the electrodes in response to the changes in the humidity of surrounding air.

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