# US 11,112,288 B2 · Thermal gas property sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,112,288 B2 - Document ID: US11112288B2 - Status: Granted - Kind: B2 - Application number: 16/489,568 - Filed: 2018-03-01 - Published: 2020-01-09 - Granted: 2021-09-07 - Earliest claimed: 2017-03-03 - Assignees: First Sensor AG - Applicants: First Sensor AG - Inventors: Oleg Grudin; Andreas Niendorf - Web page: https://patentgrep.com/patent/US11112288B2 ## CPC - G01F 1/68: by using thermal effects - G01F 1/6888: {Thermoelectric elements, e.g. thermocouples, thermopiles} - G01F 1/6845: {Micromachined devices} - G01F 1/696: Circuits therefor, e.g. constant-current flow meters - G01F 15/02: Compensating or correcting for variations in pressure, density or temperature - G01N 25/18: by investigating thermal conductivity (by calorimetry G01N25/20; by measuring change of resistance of an electrically-heated body G01N27/18) - G01N 27/18: caused by changes in the thermal conductivity of a surrounding material to be tested (G01N27/20 takes precedence) - G01N 9/00: Investigating density or specific gravity of materials; Analysing materials by determining density or specific gravity - G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME - 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 The present disclosure provides thermal gas property sensors and compensated differential pressure sensors, as well as methods for measuring a physical property of a gas and methods for compensating differential pressure sensors. A reference overpressure of a gas is generated in a cavity. Based on the flow of the gas from the cavity through a channel, properties of the gas are identified. ## Claims ### Claim 1 A gas property sensor, comprising: a semiconductor measuring device, the measuring device comprising: a cavity that carries a first gas and has at least one opening; and at least one channel in fluid communication with the cavity via an opening and with a first gas volume; a pressure generator disposed in the cavity; and one or more flow-sensitive elements located in the channel for determining a gas flow parameter, wherein the measuring device further comprises: a substrate having first and second surfaces; a first semiconductor chip portion mounted on the first surface of the substrate; and a second semiconductor chip portion mounted on the first semiconductor chip portion, the channel being defined within at least one of the first or the second semiconductor chip portion, wherein the cavity defines a partially enclosed space in the semiconductor measuring device, wherein the cavity is open only to the channel via the opening. ### Claim 2 (depends on 1) The sensor of claim 1, wherein at least a part of the cavity is further defined within the substrate. ### Claim 3 (depends on 1) The sensor of claim 1, wherein the pressure generator is a heating element. ### Claim 4 (depends on 3) The sensor of claim 3, wherein the heating element is mounted on the first surface of the substrate and/or embedded within the first surface of the substrate. ### Claim 5 (depends on 1) The sensor of claim 1, further comprising: a processing unit, wherein the processing unit is configured to determine at least one physical property of the first gas based on at least one of: a gas flow parameter, or a thermal flow parameter or the gas pressure difference, or wherein the processing unit is configured to identify a chemical composition of the first gas. ### Claim 6 (depends on 1) The sensor of claim 1, wherein determining a gas flow parameter comprises: measuring a first gas flow rate following an increase of reference gas pressure inside the cavity; measuring a second gas flow rate following a decrease of reference gas pressure inside the cavity; and determining the gas flow parameter based on a difference between the first and second gas flow rates and/or estimating gas properties by analyzing a curvature of a signal of said flow sensor. ### Claim 7 (depends on 1) The sensor of claim 1, wherein the one or more flow-sensitive elements comprise at least a first temperature sensor located at a first position in the channel and a second temperature sensor located at a second position in the channel different from the first position. ### Claim 8 (depends on 1) The sensor of claim 1, wherein the one or more flow-sensitive elements comprise: at least one heating element that is configured to heat a heat exchange element with a predetermined energy rate; and a temperature sensor sensing a temperature of the heat exchange element, wherein the heat exchange element is exposed to the gas flow in the channel. ### Claim 9 (depends on 1) The sensor of claim 1, comprising at least one of: a sensor for measuring a gas temperature or a sensor for measuring a gas pressure. ### Claim 10 (depends on 1) The gas property sensor of claim 1, included in a compensated differential gas pressure sensor, comprising: a differential pressure sensor pneumatically coupled to a first chamber that contains the same gas contained in the gas property sensor cavity and configured for measuring an uncompensated differential pressure between the first chamber and the first or a second gas volume or an ambient environment; and a processing unit configured for providing a compensated differential pressure based on the at least one of physical properties of the gas and a pressure in the first or second gas volume and the uncompensated differential pressure. ### Claim 11 (depends on 10) The gas property sensor of claim 10, wherein the differential pressure sensor is configured for measuring an uncompensated differential pressure and comprises a thermal gas flow sensor that is located in a measuring channel that is pneumatically coupled to the first chamber as well as to the first gas volume or a second gas volume. ### Claim 12 (depends on 10) The gas property sensor of claim 10, wherein the processing unit is configured to determine a quantity of the gas that has flowed through a channel in a predetermined time interval and to determine an equivalent of the gas quantity, particularly a price. ### Claim 13 (depends on 10) The gas property sensor of claim 10, included in a system with a gas tube connecting a gas reservoir with at least one gas consuming device, and wherein the system provides an indication of a quantity of the gas that has been consumed in a time interval based on a measured compensated pressure difference. ### Claim 14 A method for measuring a physical property of a gas making use of a gas property sensor comprising a semiconductor measuring device, the measuring device including: a cavity that carries a first gas and has at least one opening; at least one channel in fluid communication with the cavity via an opening and with a first gas volume, wherein the channel is defined within at least one of a first semiconductor chip portion mounted on a first surface of a substrate or a second semiconductor chip portion mounted on the first semiconductor chip portion; a pressure difference sensor measuring the pressure difference between the cavity and the first gas volume, and/or a pressure generator disposed in the cavity; and one or more flow-sensitive elements located in the channel for determining a gas flow parameter, the method comprising: receiving the gas in the cavity of the measuring device, the cavity having at least one opening; measuring an overpressure in a first case where the gas property sensor comprises a pressure difference sensor, or generating a reference overpressure of the gas in the cavity by actuating a pressure generator disposed in or near the cavity in a second case where the gas property sensor comprises a pressure generator; measuring a gas flow parameter based on movement of the gas through a channel in fluid communication with the cavity via the opening and with a first gas volume, wherein the first gas volume is an outside environment; and determining the physical property of the first gas based on at least one of: the gas flow parameter, the overpressure, an ambient temperature, a temperature of the first gas in the cavity, or an ambient pressure. ### Claim 15 (depends on 14) The method according to claim 14, wherein the gas property is determined based on a ratio of the gas flow parameter representing a quantity of a gas flow and the overpressure. ### Claim 16 (depends on 14) The method according to claim 14, wherein a reference overpressure is generated by heating the gas in the cavity. ### Claim 17 (depends on 16) The method according to claim 16, wherein the gas flow is measured after establishing a stationary thermal condition in the cavity, wherein the stationary thermal condition includes a stable temperature gradient in the cavity. ### Claim 18 (depends on 14) The method according to claim 14, further comprising: measuring at least one of: an ambient temperature, an absolute pressure of the first gas in the cavity, an absolute gas pressure in the first gas volume, a gas viscosity of the first gas, a thermal conductivity of the first gas, or a thermal capacity of the first gas. ### Claim 19 (depends on 14) The method of claim 14, in combination with a second method for measuring a compensated differential gas pressure between a first chamber and the first gas volume, a second gas volume, or an ambient environment, the second method further comprising: measuring an uncompensated pressure difference between the first chamber that the same gas carried in the gas property sensor cavity and the first gas volume, the second gas volume, or the ambient environment, and determining a compensated pressure difference value based on a measured physical property of the gas and a result of the uncompensated pressure difference measurement.