Gas sensor with electrically conductive, hydrophobic membranes
First Claim
1. A gas sensor comprising, in combination:
- a first electrode and a second electrode;
an ion conducting, solid electrolyte membrane positioned between the first electrode and the second electrode, wherein an electric signal is produced between the first electrode and the second electrode in response to the presence of a gas at the first electrode;
means for measurement of the electric signal; and
a top membrane comprising an electrically conductive, hydrophobic, gas permeable material electrically connecting the first electrode with the means for measurement of the electric signal, wherein the gas reaches the first electrode by diffusing through the electrically conductive, hydrophobic, gas permeable material.
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Accused Products
Abstract
A highly accurate, long life, low cost gas sensor is disclosed, particularly useful for measuring carbon monoxide and other toxic gases in an environment. The gas sensor has a first, sensing electrode and a second, counting electrode. Positioned between the first and second electrodes is an ion conducting, solid electrolyte membrane. In response to the presence of a toxic gas introduced to the first electrode, an electric signal is produced between the first electrode and the second electrode. The electric signal changes in response to changes in the concentration of the toxic gas. Detection circuitry measures the electric signal to determine the concentration of the toxic gas. An electrically conductive, hydrophobic top membrane electrically connects the first electrode to the detection circuitry while preventing liquid water from contacting the first electrode. An electrically conductive, hydrophobic bottom membrane electrically connects the second electrode to the detection circuitry. The top and bottom membranes, though hydrophobic, are preferably also microporous so as to be gas permeable, including permeable to water vapor. Preferably the top and bottom membranes are ion insulating as well. Optionally the sensor is provided with a water reservoir to maintain constant relative humidity at the ion conducting electrolyte membrane. The sensor may also have a heating element. Internal and external self-diagnostic features to ensure that the sensor is functioning normally are disclosed, as well as self-calibration features, so as to ensure sensor accuracy.
59 Citations
37 Claims
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1. A gas sensor comprising, in combination:
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a first electrode and a second electrode;
an ion conducting, solid electrolyte membrane positioned between the first electrode and the second electrode, wherein an electric signal is produced between the first electrode and the second electrode in response to the presence of a gas at the first electrode;
means for measurement of the electric signal; and
a top membrane comprising an electrically conductive, hydrophobic, gas permeable material electrically connecting the first electrode with the means for measurement of the electric signal, wherein the gas reaches the first electrode by diffusing through the electrically conductive, hydrophobic, gas permeable material. - 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)
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29. A gas sensor comprising, in combination:
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a first electrode and a second electrode;
an ion conducting, solid electrolyte membrane positioned between the first electrode and second electrode, wherein an electric signal is produced between the first electrode and the second electrode in response to the presence of a gas at the first electrode;
means for measurement of the electric signal between the first electrode and the second electrode; and
a bottom membrane, comprising a material that is electrically conductive, hydrophobic, and permeable to water vapor, electrically connecting the means for measurement of the electrical signal with the second electrode;
wherein the bottom membrane separates the second electrode from a reservoir of an aqueous liquid, the reservoir providing a water vapor source for maintaining constant relative humidity at the ion conducting, solid electrolyte membrane. - View Dependent Claims (30, 31, 32, 33)
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34. A gas sensor comprising, in combination:
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a first electrode and a second electrode, wherein ions are generated at the first electrode in response to the presence of a gas;
a solid electrolyte membrane in electrical communication with the first electrode and the second electrode, conducting ions generated at the first electrode to the second electrode, wherein an electric signal is produced between the first electrode and the second electrode in response to the presence of the gas;
means for measurement of the electric signal between the first electrode and to the second electrode; and
a bottom membrane, comprising a material that is electrically conductive, hydrophobic, permeable to water vapor, and ion insulating, electrically connecting the means for measurement of the electrical signal with the second electrode;
wherein the bottom membrane separates the second electrode from a reservoir of an aqueous liquid, the reservoir providing a water vapor source for maintaining constant relative humidity at the ion conducting, solid electrolyte membrane. - View Dependent Claims (35, 36, 37)
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Specification