Solid polymer electrolyte oxygen sensor
First Claim
1. A gas sensor comprising:
- a block of a solid electrolyte;
a sensing electrode in electrical contact with the block; and
a counter electrode in electrical contact with the block, wherein;
the sensing electrode catalyzes a reaction of oxygen with hydrogen ions and electrons to produce water;
a biasing of the counter electrode breaks down water to produce electrons and hydrogen ions in the block; and
a current through the sensing electrode caused by the electrons captured indicates a measured oxygen concentration.
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Abstract
An oxygen sensor includes a solid polymer electrolyte, e.g., on an acid treated Nafion membrane and uses a diffusion-limited fuel cell type reactions. The sensor avoids electrolyte leakage and avoids consumption of electrodes. In different configurations, a counter or reference electrode can be on the same or the opposite side of the electrolyte as a sensing electrode. An insert limits and controls oxygen diffusion into a sensing chamber containing the sensing electrode that catalyzes reduction of oxygen. Applying appropriate bias voltages to the reference and sensing electrodes causes an output current of the sensing electrode to be proportional to the rate of oxygen consumption based on Frick'"'"'s law under a diffusion-limited mode. The output current can be measured, e.g., using a resistor to convert the current to a voltage signal.
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Citations
60 Claims
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1. A gas sensor comprising:
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a block of a solid electrolyte;
a sensing electrode in electrical contact with the block; and
a counter electrode in electrical contact with the block, wherein;
the sensing electrode catalyzes a reaction of oxygen with hydrogen ions and electrons to produce water;
a biasing of the counter electrode breaks down water to produce electrons and hydrogen ions in the block; and
a current through the sensing electrode caused by the electrons captured indicates a measured oxygen concentration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. An oxygen sensor comprising:
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a block of a solid electrolyte;
first, second, and third electrodes in electrical contact with the block;
first, second, and third terminals in electrical contact respectively with the first, second, and third electrodes, wherein the first, second, and third terminals are electrically isolated from each other to permit independent biasing of the first, second, and third electrodes; and
an electronic circuit that is connected to the first, second, and third terminals to bias the first, second, and third electrodes and measure a current indicating a target gas. - View Dependent Claims (35, 36, 37)
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38. A button-type oxygen sensor comprising:
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a block of a solid polymer electrolyte;
a first electrode on a first surface of the block;
a second electrode on a second surface of the block; and
a rigid housing including a first portion in electrical contact with the first electrode and a second portion in electrical contact with the second electrode. - View Dependent Claims (39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57)
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58. A method for sensing gaseous oxygen in a sample gas, comprising:
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controlling a rate of diffusion of oxygen from the sample gas into a sensing chamber;
catalyzing a reaction at a first electrode that is in electrical contact with a solid electrolyte, wherein the reaction causes oxygen to capture hydrogen ions and electrons to produce water;
applying a bias voltage between a second electrode in contact with the solid electrolyte to cause a reaction that releases hydrogen ions and electrons; and
measuring a current through the first electrode that results from a reaction of the ions with oxygen in the sensing chamber. - View Dependent Claims (59, 60)
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Specification