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Dew-point sensor

  • US 4,948,263 A
  • Filed: 06/09/1988
  • Issued: 08/14/1990
  • Est. Priority Date: 06/16/1987
  • Status: Expired due to Fees
First Claim
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1. A dew-point sensor for a dew-point measuring device for measuring the water dew-point in gases, comprising:

  • a sensor surface which is exposed to the gas to be measured;

    means for cooling said sensor surface to a dew-point temperature at which water vapor condenses on said sensor surface;

    a first electrode structure having a first electrode portion mounted on said sensor surface;

    a second electrode structure having a second electrode portion mounted on said sensor surface at a uniform distance of less than 50 μ

    m from said first electrode portion;

    a moisture-insensitive insulating layer covering said first electrode portion and said second electrode portion and having a thickness smaller than said uniform distance between said first and second electrode portions to maintain a gap between said electrode portions; and

    whereby the insulating layer forms a parallel capacitance-resistance in series with the capacitance-resistance between the electrodes and the electrode resistance such that formation of condensed droplets fill the gap between electrode portions to cause a large change of the impedance or capacitance between the two electrode structures when the dew-point temperature is reached.

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