Gas sensor with dual electrolytes
First Claim
1. A gas sensor for measurement of a gas in an environment comprising, in combination:
- a first electrode;
a membrane permeable to the gas and impermeable to water vapor, positioned between the environment and the first electrode;
a second electrode;
a solid electrolyte positioned between the first electrode and the second electrode;
a liquid electrolyte isolated from the gas to be measured, positioned between the first electrode and the second electrode, electrically serially connected to the solid electrolyte, and cooperating with the solid electrolyte in response to an electric current to produce a voltage between the first electrode and the second electrode, wherein the voltage changes in response to changes in the concentration of the gas wherein the second electrode is in direct contact with the liquid electrolyte; and
means for electrical measurement of the voltage electrically connected to the first electrode and the second electrode.
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Accused Products
Abstract
A highly accurate, long life, low cost gas sensor is disclosed, particularly useful for measuring oxygen in an environment. The gas sensor has a first, sensing electrode and a second, counting electrode. Dual electrolytes are electrically serially connected between the first and second electrodes. One of the electrolytes is an ion conducting solid electrolyte, the second is a liquid electrolyte. In response to an electric current an electrical characteristic is produced, and the electrical characteristic changes in response to changes in the concentration of a gas such as oxygen introduced at the first, sensing electrode. The solid electrolyte can be a perfluorinated polymer which advantageously controls the rate of the electrochemical reaction to give the sensor a long life without need for continuous recalibration. A dense liquid impermeable membrane may be positioned over the first electrode so that only gas reaches the first electrode and all gas that reaches the first electrode passes through the membrane. Advantageously, the solid electrolyte isolates the liquid electrolyte from the first, sensing electrode. The liquid electrolyte may comprise an acidic solution, a basic solution or a salt solution.
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Citations
30 Claims
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1. A gas sensor for measurement of a gas in an environment comprising, in combination:
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a first electrode; a membrane permeable to the gas and impermeable to water vapor, positioned between the environment and the first electrode; a second electrode; a solid electrolyte positioned between the first electrode and the second electrode; a liquid electrolyte isolated from the gas to be measured, positioned between the first electrode and the second electrode, electrically serially connected to the solid electrolyte, and cooperating with the solid electrolyte in response to an electric current to produce a voltage between the first electrode and the second electrode, wherein the voltage changes in response to changes in the concentration of the gas wherein the second electrode is in direct contact with the liquid electrolyte; and means for electrical measurement of the voltage electrically connected to the first electrode and the second electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An oxygen sensor comprising, in combination:
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a solid polymer membrane permeable to oxygen and impermeable to water vapor; a solid polymer electrolyte having a top surface and a bottom surface and being capable of conducting ions between the top surface and the bottom surface; a liquid electrolyte isolated from the gas to be measured, electrically connected to the solid polymer electrolyte; a metal in direct contact with the liquid electrolyte, wherein in response to electrical current the metal is oxidized in an oxidation reaction; and an electrically conductive metal film in electrical connection with the top surface of the solid polymer electrolyte and separated from the liquid electrolyte by the solid electrolyte; wherein oxygen passes through the polymer membrane, and in response to an electric current ions are conducted through the solid polymer electrolyte to react with the oxygen in a reduction reaction near the top surface of the solid polymer electrolyte. - View Dependent Claims (19, 20, 21)
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22. A sensor for sensing oxygen in an environment comprising, in combination:
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a first electrode; a polymer membrane permeable to oxygen and impermeable to water vapor, positioned between the environment and the first electrode; a second electrode, wherein in response to an electric current a voltage is produced between the first electrode and the second electrode which is proportional to the concentration of oxygen sensed at the first electrode; a first electrolyte and a second electrolyte, wherein the first electrolyte is in direct contact with the second electrolyte such that the first electrolyte isolates the first electrode from the second electrolyte, and the second electrolyte is isolated from the oxygen to be sensed and the second electrode is in direct contact with the second electrolyte. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30)
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Specification