Fiber optic CO.sub.2 sensor
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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Abstract
A fiber-optic probe for measuring the partial pressure of CO2 in a medium includes a single optical fiber having a distal end; a mirror; a hydrolyzed dye/gel polymer, the dye being in contact with a bicarbonate solution; a solution permeable membrane covering the fiber distal end, hydrogel and mirror; and a gas-permeable membrane covering the solution permeable membrane.
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Citations
9 Claims
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1. A fiber-optic probe for measuring the partial pressure of carbon dioxide in a medium, comprising:
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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, and means for transmitting absorbable light from the hydrolyzed hydrogel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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Specification