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Fiber optic CO.sub.2 sensor

  • US 4,943,364 A
  • Filed: 06/23/1986
  • Issued: 07/24/1990
  • Est. Priority Date: 06/21/1985
  • Status: Expired due to Term
First Claim
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1. A fiber-optic probe for measuring the partial pressure of carbon dioxide in a medium, comprising:

  • a gas-permeable membrane;

    a hydrolyzed hydrogel including a dye/bicarbonate/gel acrylic or ethylene oxide polymer within the gas/permeable membrane, the hydrogel having been prepared from a chemically and optically unstable dye/gel acrylic or ethylene oxide polymer which, prior to treatment, contains weakly bonded dye molecules and exhibits a substantial drift in measured pH with time accompanied by an increase in protonation constant, by a treatment comprising (1) contacting the unstable polymer with a dilute aqueous base solution for a period of time sufficient to remove weakly bonded dye molecules from the polymer (2) washing the base-treated polymer with water to remove substantially all the base, (3) contacting the washed polymer with a solvent having a high affinity for water to remove water from the polymer and give a polymer characterized by chemical and optical stability with respect to dye loss with time and a consistently repeatable protonation constant, and (4) conditioning the stable polymer by contacting it with a bicarbonate solution;

    means for providing light to the hydrolyzed hydrogel, andmeans for transmitting absorbable light from the hydrolyzed hydrogel.

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