# US 10,768,133 B2 · Integrated SMO gas sensor module > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,768,133 B2 - Document ID: US10768133B2 - Status: Granted - Kind: B2 - Application number: 15/723,661 - Filed: 2017-10-03 - Published: 2018-02-01 - Granted: 2020-09-08 - Earliest claimed: 2014-07-17 - Assignees: Stmicroelectronics Pte Ltd - Applicants: STMicroelectronics Pte Ltd - Inventors: Ravi Shankar; Olivier Le Neel; Tien-Choy Loh; Shian-Yeu Kam - Web page: https://patentgrep.com/patent/US10768133B2 ## CPC - G01N 27/12: of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid {, for detecting components in the fluid} - G01N 27/123: {for controlling the temperature (temperature control per se G05D23/00)} - G01N 27/125: {Composition of the body, e.g. the composition of its sensitive layer} - G01N 27/128: {Microapparatus} - G01N 27/129: {Diode type sensors, e.g. gas sensitive Schottky diodes (capacitor type sensors G01N27/227; field-effect transistor type sensors G01N27/414)} - G01N 27/227: {Sensors changing capacitance upon adsorption or absorption of fluid components, e.g. electrolyte-insulator-semiconductor sensors, MOS capacitors (G01N27/225 takes precedence)} - 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) ## Abstract Miniature resistive gas detectors incorporate thin films that can selectively identify specific gases when heated to certain characteristic temperatures. A solid state gas sensor module is disclosed that includes a gas sensor, a heater, and a temperature sensor, stacked over an insulating recess. The insulating recess is partially filled with a support material that provides structural integrity. The solid state gas sensor module can be integrated on top of an ASIC on a common substrate. With sufficient thermal insulation, such a gas detector can be provided as a low-power component of mobile electronic devices such as smart phones. A method of operating a multi-sensor array allows detection of relative concentrations of different gas species by either using dedicated sensors, or by thermally tuning the sensors to monitor different gas species. ## Claims ### Claim 1 A gas sensor array, comprising: a substrate; and a plurality of solid state gas sensor array elements on the substrate, each of the plurality of solid state gas sensor array element including: a semiconductor metal oxide (SMO) sensor on the substrate; a temperature sensor on the substrate; a heater on the substrate; an air gap, the SMO sensor, the temperature sensor, and the heater being spaced from the substrate by the air gap; supports that extend through the air gap; a first signal line coupled to the SMO sensor; a second signal line coupled to the temperature sensor; and a third signal line coupled to the heater. ### Claim 2 (depends on 1) The gas sensor array of claim 1 wherein the SMO sensor, the temperature sensor, and the heater are housed in a thermally insulated unit integrated into the substrate. ### Claim 3 (depends on 1) The gas sensor array of claim 1 wherein the gas sensor array has a total footprint area less than about 2.5 mm2. ### Claim 4 (depends on 1) The gas sensor array of claim 1 wherein the SMO sensor includes dopants. ### Claim 5 (depends on 1) The gas sensor array of claim 1 wherein the SMO sensor is doped with one or more of palladium (Pd), platinum (Pt), or silver (Ag). ### Claim 6 (depends on 1) The gas sensor array of claim 1 wherein the SMO sensor has a variable resistance that changes with temperature. ### Claim 7 (depends on 1) The gas sensor array of claim 1 wherein the heater is configured to heat the SMO sensor to a selected temperature at which the SMO sensor is predominantly sensitive to a selected gas species. ### Claim 8 (depends on 7) The gas sensor array of claim 7 wherein the selected gas species is one of ethanol vapor, carbon monoxide (CO), methane (CH4), hydrogen sulfide (H2S), and sulfur dioxide (SO2). ### Claim 9 A device, comprising: a substrate; and a plurality of solid state gas sensor modules arranged in an array on the substrate, each of the plurality of solid state gas sensor modules, including: a cavity in the substrate; a semiconductor metal oxide (SMO) sensor that is spaced from the substrate by the cavity; a heater that is spaced from the substrate by the cavity; a temperature sensor that is spaced from the substrate by the cavity; and support pillars in the cavity, the SMO sensor, the heater, and the temperature sensor being spaced from the substrate by the support pillars. ### Claim 10 (depends on 9) The device of claim 9, further comprising: an integrated circuit on the substrate, the integrated circuit being configured to control a heater of a first solid state gas sensor module of the plurality of solid state gas sensor modules to heat an SMO sensor of the first solid state gas sensor to a first temperature, the integrated circuit being configured to control a heater of a second solid state gas sensor module of the plurality of solid state gas sensor modules to heat an SMO sensor of the second solid state gas sensor to a second temperature, the second temperature being different from the first temperature. ### Claim 11 (depends on 9) The device of claim 9 wherein the heater is configured to heat the SMO sensor to a selected temperature at which the SMO sensor is sensitive to a selected gas species. ### Claim 12 (depends on 9) The device of claim of claim 9 wherein the SMO sensor is spaced from the heater by temperature sensor. ### Claim 13 A device, comprising: a substrate; a plurality of gas sensor modules on the substrate, each of the plurality of gas sensor modules including: a cavity in the substrate; an insulating layer that is spaced from the substrate by the cavity; a gas sensor on the insulating layer; a heater on the insulating layer; and a temperature sensor on the insulating layer; and support pillars in the cavity, the gas sensor, the heater, and the temperature sensor being spaced from the substrate by the support pillars. ### Claim 14 (depends on 13) The device of claim 13 wherein the gas sensor is a semiconductor metal oxide (SMO) sensor. ### Claim 15 (depends on 13) The device of claim 13 wherein the heater is configured to heat the gas sensor to a selected temperature at which the gas sensor is sensitive to a selected gas species. ### Claim 16 (depends on 13) The device of claim 13, further comprising: an integrated circuit on the substrate, the integrated circuit being configured to control the heater to heat the gas sensor to a selected temperature at which the gas sensor is sensitive to a selected gas species.