# US 7,329,389 B2 · Sensor device and method for qualitative and quantitative analysis of gas phase substances > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,329,389 B2 - Document ID: US7329389B2 - Status: Granted - Kind: B2 - Application number: 10/192,782 - Filed: 2002-07-09 - Published: 2003-02-27 - Granted: 2008-02-12 - Earliest claimed: 2001-07-16 - Assignees: Sensor Tech, Inc. - Inventors: Michael L. Horovitz; Karl F. Anderson - Web page: https://patentgrep.com/patent/US7329389B2 ## CPC - G01N 27/123: {for controlling the temperature (temperature control per se G05D23/00)} - G01N 27/16: caused by burning or catalytic oxidation of surrounding material to be tested, e.g. of gas - G01N 27/3271: {Amperometric enzyme electrodes for analytes in body fluids, e.g. glucose in blood (amperometry per se G01N27/49; aspects concerning the enzyme reagent C12Q1/001)} - G01N 33/497: of gaseous biological material, e.g. breath - Y10T 29/49: Method of mechanical manufacture - Y10T 29/49002: Electrical device making - Y10T 436/11: Automated chemical analysis - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## 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. ## Claims ### 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, 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. ### Claim 2 (depends on 1) The sensor of claim 1, wherein the sensing element further comprises a first heat conductor in thermal contact with the first heater and wherein the reference element further comprises a second heat conductor in thermal contact with the second heater. ### Claim 3 (depends on 1) The sensor of claim 1, wherein the first heater is a first variable resistance heater and wherein the second heater is a second variable resistance heater. ### Claim 4 (depends on 1) The sensor of claim 1, wherein the first temperature detector is a first resistance temperature detector and wherein the second temperature detector is a second resistance temperature detector. ### Claim 5 (depends on 4) The sensor of claim 4, wherein the heat flow monitor comprises an Anderson Loop measurement circuit topology, and wherein the change in heat flow is measured as a difference in the electrical resistance of the first resistance temperature detector compared to the second resistance temperature detector. ### Claim 6 (depends on 4) The sensor of claim 4, wherein the heat flow monitor comprises a Wheatstone bridge measurement circuit topology, and wherein the change in heat flow is measured as a difference in the electrical resistance of the first resistance temperature detector compared to the second resistance temperature detector. ### Claim 7 (depends on 1) The sensor of claim 1, further comprising a feedback control system to maintain the sensing element at a desired instantaneous temperature. ### Claim 8 (depends on 1) The sensor of claim 1, wherein the catalyst is selected from a metal oxide, boride, carbide, silicide, nitride, phosphide, arsenide, sulfide, selenide, telluride, fluoride, chloride, bromide, or iodide; a non-metal oxide, boride, carbide, silicide, nitride, phosphide, arsenide, sulfide, selenide, telluride, fluoride, chloride, bromide, or iodide; a metal; an alloy; a substance in which more than one metal or more than one nonmetal are combined with an element; a substance in which a metal or a non-metal are combined with more than one other element; or a combination thereof. ### Claim 9 (depends on 1) The sensor of claim 1, wherein the catalyst comprises a metal, a metal oxide, or a combination thereof. ### Claim 10 (depends on 1) The sensor of claim 1, wherein the catalyst is selected from an oxide of scandium, titanium, zirconium, hafnium, niobium, tantalum, vanadium, nickel, manganese, iron, copper, chromium, cobalt, molybdenum, tungsten, osmium, rhenium, rhodium, palladium, silver, iridium, platinum, zinc, aluminum, tin, or a combination thereof. ### Claim 11 (depends on 1) The sensor of claim 1, wherein the sensing element is heated to a temperature by electrical power and, wherein the heat flow monitor measures a change in the amount of power required to hold the sensing element at the temperature after the sensing element is contacted with the gas phase substances. ### Claim 12 (depends on 1) The sensor of claim 1, wherein the sensing and reference elements are heated to a temperature by electrical power and, wherein the heat flow monitor measures a difference in the amount of power required to hold the sensing element at temperature compared to the amount of power required to hold the reference element at the specific temperature, after the sensing and reference elements are contacted with the gas phase substances. ### Claim 13 (depends on 1) The sensor of claim 1, wherein the heat flow monitor determines a temperature change of the sensing element as a result of an exothermic or endothermic interaction between the catalyst and the gas phase substance. ### Claim 14 (depends on 1) The sensor of claim 1, wherein the heat flow monitor determines a temperature change of the sensing element as a result of an exothermic or endothermic interaction between the catalyst and the gas phase substance, as compared to the temperature of the reference element. ### Claim 15 (depends on 1) The sensor of claim 1, wherein the interaction between the catalyst and gas phase substance comprise at least one of an oxidation, a reduction, an acid-base reaction, an adsorption, a desorption, a hydrogen-bonding process, a van der Waals interaction, an electrostatic interaction, a bond-making reaction, a bond-breaking reaction, or a combination thereof. ### Claim 16 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 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. ### Claim 17 (depends on 16) The sensor of claim 16, wherein the first and second resistance temperature detectors comprise a material selected from nickel, platinum, or tungsten. ### Claim 18 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 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. ### Claim 19 A method of detecting a gas substance at a predetermined temperature comprising: 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 comprises 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 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. ### Claim 20 (depends on 19) The method of claim 19, wherein the sensing element further comprises a first heat conductor in thermal contact with the first heater and wherein the reference element further comprises a second heat conductor in thermal contact with the second heater. ### Claim 21 (depends on 19) The method of claim 19, wherein the first heater is a first variable resistance heater and wherein the second heater is a second variable resistance heater. ### Claim 22 (depends on 19) The method of claim 19, wherein the first temperature detector is a first resistance temperature detector and wherein the second temperature detector is a second resistance temperature detector. ### Claim 23 (depends on 19) The method of claim 19, wherein the catalyst is selected from a metal oxide, boride, carbide, suicide, nitride, phosphide, arsenide, sulfide, selenide, telluride, fluoride, chloride, bromide, or iodide; a non-metal oxide, boride, carbide, silicide, nitride, phosphide, arsenide, sulfide, selenide, telluride, fluoride, chloride, bromide, or iodide; a metal; an alloy, a substance in which more than one metal or more than one nonmetal are combined with an element; a substance in which a metal or a non-metal are combined with more than one other element; or a combination thereof. ### Claim 24 (depends on 19) The method of claim 19, wherein the interaction between the catalyst gas phase substance comprise at least one of an oxidation, a reduction, an acid-base reaction, an adsorption, a desorption, a hydrogen-bonding process, a van der Waals interaction, an electrostatic interaction, a bond-making reaction, a bond-breaking reaction, or a combination thereof. ### Claim 25 (depends on 19) The method of claim 19, further comprising employing a feedback control system to maintain the sensing element at the temperature at which the interaction occurs. ### Claim 26 (depends on 19) The method of claim 19, wherein the temperature of the sensing element and the reference element are regulated between about −196° C. and about 260° C. ### Claim 27 (depends on 19) The method of claim 19, wherein the temperature of the sensing element and the reference element are regulated between about −78° C. and about 232° C. ### Claim 28 (depends on 19) The method of claim 19, wherein the temperature of the sensing element and the reference element are regulated between about 0° C. and about 232° C. ### Claim 29 (depends on 19) The method of claim 19, wherein the temperature of the sensing element and the reference element are regulated between about 25° C. and about 200° C. ### Claim 30 (depends on 19) The method of claim 19, wherein measuring the heat flow to and from the sensing element is determined by measuring either a change in temperature of the sensing element or a change in non-catalytic power required to maintain the sensing element at the temperature at which the interaction occurs. ### Claim 31 (depends on 19) The method of claim 19, wherein measuring the heat flow to and from the sensing element is determined by measuring either a temperature difference between the sensing and reference elements or a difference in non-catalytic power supplied to the sensing element compared to the non-catalytic power supplied to the reference element in order to maintain both the sensing and reference elements at the temperature at which the interaction occurs. ### Claim 32 A method of detecting a gas phase substance at a predetermined temperature, comprising: 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 comprises 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 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. ### Claim 33 (depends on 32) The method of claim 32, wherein the first and second resistance temperature detectors comprise a material selected from nickel, platinum, or tungsten. ### Claim 34 A meted of detecting a gas phase substance at a predetermined temperature comprising: 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. ### Claim 35 A method of detecting multiple gas phase substances by calorimetric spectroscopy, comprising: 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; and b) 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. ### Claim 36 (depends on 35) The method of claim 35, further comprising employing a feedback control system to maintain the sensing element at a temperature set by the predetermined temperature and time profile. ### Claim 37 (depends on 35) The method of claim 35, wherein the temperature of the sensing element and the reference element are regulated over a range of between −196° C. to about 260° C. ### Claim 38 (depends on 35) The method of claim 35, wherein the interaction between the catalyst and gas phase substance comprise at least one of an oxidation, a reduction, an acid-base reaction, an adsorption, a desorption, a hydrogen-bonding process, a van der Waals interaction, an electrostatic interaction, a bond-making reaction, a bond-breaking reaction, or a combination thereof.