Sensor device and method for qualitative and quantitative analysis of gas phase substances
First Claim
1. A sensor for detecting gas phase substances, comprising:
- a) a sensing element in contact with the gas phase substances, comprising;
a first supporting substrate,a first heater attached to the first supporting substrate,a first temperature detector in thermal contact with the first heater, anda catalyst in thermal contact with the first temperature detector and the first heater, wherein the catalyst interacts with the gas phase substances, and wherein the interaction comprises one of endothermic and exothermic heat flow from the catalyst to the first temperature detector;
b) a reference element in contact with the gas phase substances, comprising;
a second supporting substrate,a second heater attached to the second supporting substrate,a second temperature detector in thermal contact with the second heater; and
c) a thermal barrier separating the sensing element from the reference element, andd) a heat flow monitor connected to both the sensing and reference elements for measuring any change in heat flow between the sensing element relative to the reference element.
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Accused Products
Abstract
New sensors and methods for qualitative and quantitative analysis of multiple gaseous substances simultaneously with both high selectivity and high sensitivity are provided. The new sensors rely on a characteristic difference in energy between the interaction of a particular substance with a catalyst coated heat transfer device (HTD) and a non-catalyst coated (or one coated with a different catalyst) reference HTD. Molecular detection is achieved by an exothermic or endothermic chemical or physical reaction between the catalytic surface of the sensor and the molecule, tending to induce a temperature change of the sensor. Both high temperature and non-destructive low temperature detection are possible. The magnitude and rate of endothermic or exothermic heat transfer from a specific molecule-catalyst interaction is related to molecular concentration.
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Citations
38 Claims
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1. A sensor for detecting gas phase substances, comprising:
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a) a sensing element in contact with the gas phase substances, comprising; a first supporting substrate, a first heater attached to the first supporting substrate, a first temperature detector in thermal contact with the first heater, and a catalyst in thermal contact with the first temperature detector and the first heater, wherein the catalyst interacts with the gas phase substances, and wherein the interaction comprises one of endothermic and exothermic heat flow from the catalyst to the first temperature detector; b) a reference element in contact with the gas phase substances, comprising; a second supporting substrate, a second heater attached to the second supporting substrate, a second temperature detector in thermal contact with the second heater; and c) a thermal barrier separating the sensing element from the reference element, and d) a heat flow monitor connected to both the sensing and reference elements for measuring any change in heat flow between the sensing element relative to the reference element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A sensor for detecting gas phase substances, comprising:
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a) a sensing element in contact with the gas phase substances, comprising; a first supporting substrate, a first resistance temperature detector which functions as a temperature detector and a variable resistance heater attached to the first supporting substrate, and a catalyst in thermal contact with the first resistance temperature detector, wherein the catalyst interacts with the gas phase substances, and wherein the interaction comprises one of endothermic and exothermic heat flow from the catalyst to the first resistance temperature detector; b) a reference element in contact with the gas phase substances, comprising; a second supporting substrate, a second resistance temperature detector which functions as a temperature detector and a variable resistance heater attached to the second supporting substrate; and c) a thermal barrier separating the sensing element from the reference element; and d) a heat flow monitor connected to both the sensing and reference elements for measuring any change in heat flow between the sensing element relative to the reference element. - View Dependent Claims (17)
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18. A sensor for detecting gas phase substances, comprising:
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a) a sensing element in contact with the gas phase substances, comprising; a first supporting substrate, a first resistance temperature detector which functions as a temperature detector and a variable resistance heater attached to the first supporting substrate, and a metal oxide catalyst in thermal contact with the first resistance temperature detector, wherein the metal oxide catalyst interacts with the gas phase substances, and wherein the interaction comprises one of endothermic and exothermic heat flow from the metal oxide catalyst to the first resistance temperature detector; b) a reference element in contact with the gas phase substances, comprising; a second supporting substrate, a second resistance temperature detector which functions as a temperature detector and a variable resistance heater attached to the second supporting substrate; and c) a thermal barrier separating the sensing element from the reference element; and d) a heat flow monitor connected to both the sensing and reference elements for measuring any change in heat flow between the sensing element relative to the reference element by monitoring the change in electric power needed to maintain the first resistance temperature detector at a desired temperature relative to the second resistance temperature detector, the heat flow monitor comprising an Anderson Loop measurement circuit topology; and
a feedback control system, to maintain the sensing element at the desired temperature.
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19. A method of detecting a gas substance at a predetermined temperature comprising:
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a) contacting the gas phase substance with a sensing element and reference element, wherein the sensing element comprises; a first supporting substrate, a first heater attached to the first supporting substrate, a first temperature detector in thermal contact with the first heater; a catalyst in thermal contact with the first temperature detector and the first heater, wherein the catalyst interacts at a temperature with the gas phase substance, and wherein the interaction comprises one of endothermic and exothermic heat flow from the catalyst to the first temperature detector; and
wherein the reference element comprisesa second supporting substrate, a second heater attached to the second supporting substrate, a second temperature detector in thermal contact with the second heater, and wherein the sensing and reference elements are separated from one another by a thermal barrier; and b) regulating the temperature of the sensing element and the reference element to substantially match the temperature at which the interaction occurs between the catalyst and the substance; and c) measuring the heat flow to and from the sensing element relative to the reference element, with a heat flow monitor connected to both the sensing and reference elements and wherein detection of a change in heat flow at the sensing element relative to the reference element indicates detection of the gas phase substance. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A method of detecting a gas phase substance at a predetermined temperature, comprising:
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a) contacting the gas phase substance with a sensing element and a reference element, wherein the sensing element comprises a first supporting substrate, a first resistance temperature detector which functions as a temperature detector and a variable resistance heater attached to the first supporting substrate, and a catalyst in thermal contact with the first resistance temperature detector, wherein the catalyst interacts with the gas phase substance, and wherein the interaction comprises one of endothermic and exothermic heat flow from the catalyst to the first resistance temperature detector; and
wherein the reference element comprisesa second supporting substrate, a second resistance temperature detector which functions as a temperature detector and a variable resistance heater attached to the second supporting substrate, and wherein the sensing and reference elements are separated from one another by a thermal barrier; and b) regulating the temperature of the sensing element and the reference element to substantially match the specific temperature at which the interaction occurs between the catalyst and the gas phase substance; and c) measuring the heat flow to and from the sensing element relative to the reference element, with a heat flow monitor connected to both the sensing and reference elements and wherein detection of a change in heat flow at the sensing element relative to the reference element indicates detection of the gas phase substance. - View Dependent Claims (33)
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34. A meted of detecting a gas phase substance at a predetermined temperature comprising:
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a) contacting the gas phase substance with a sensing element, wherein the sensing element comprises a first supporting substrate, a first variable resistance heater attached to the first supporting substrate, and a first temperature detector in thermal contact with the first variable resistance heater, and a catalyst in thermal contact with the first temperature detector, wherein the catalyst interacts with the gas phase substance, and wherein the interaction comprises one of endothermic and exothermic heat flow from the catalyst to the first variable resistance heater; b) regulating the temperature of the sensing element to substantially match a temperature at which the interaction occurs between the catalyst and the substance; c) measuring the endothermic or exothermic heat flow at the sensing element with a heat flow monitor connected to the sensing element; d) contacting the gas phase substance with a reference element, wherein the reference element comprises a second supporting substrate, a second variable resistance heater attached to the second supporting substrate, and a second temperature detector in thermal contact with the second variable resistance heater; e) regulating the temperature of the reference element to substantially match a temperature of the sensing element; f) measuring the heat flow at the reference element with the heat flow monitor that is connected to the reference element; and g) comparing the heat flow at the sensing element with the heat flow at the reference element, wherein a difference in heat flow at the sensing element compared to the reference element indicates detection of the gas phase substance.
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35. A method of detecting multiple gas phase substances by calorimetric spectroscopy, comprising:
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a) contacting the gas phase substance with at least one sensing element and at least one reference element, wherein the sensing element comprises a first supporting substrate, a first variable resistance heater attached to the first supporting substrate, a first temperature detector in thermal contact with the first variable resistance heater, and a catalyst in thermal contact with the first temperature detector and the first variable resistance heater, wherein the catalyst interacts with the gas phase substance, and wherein the interaction comprises one of endothermic and exothermic heat flow from the catalyst to the first temperature detector; and
wherein the reference element comprises a second supporting substrate,a second supporting substrate, a second variable resistance heater attached to the second supporting substrate, a second temperature detector in thermal contact with the second variable resistance heater; and
wherein a thermal barrier separates each pair of sensing and reference elements; andb) increasing or decreasing the temperature in the sensing element and the reference element concurrently over a predetermined temperature and time profile, such that one or more temperatures at which the interaction occurs between the catalyst and each gas phase substance is achieved; and c) measuring the heat flow at the sensing element relative to the reference element over the predetermined temperature and time profile, with a heat monitor connected to both the sensing and reference elements, wherein a difference in heat flow at the sensing element compared to the reference element at one or more temperatures indicate the detection of a particular gas substance. - View Dependent Claims (36, 37, 38)
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Specification