# US 2018/0321186 A1 · Systems and methods for determining the condition of a gas sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0321186 A1 - Document ID: US20180321186A1 - Status: Published application - Kind: A1 - Application number: 15/586,849 - Filed: 2017-05-04 - Published: 2018-11-08 - Earliest claimed: 2017-05-04 - Assignees: Analog Devices Global - Inventors: Michael Looney; GuangYang Qu - Web page: https://patentgrep.com/patent/US20180321186A1 ## CPC - G01N 27/4163: {checking the operation of, or calibrating, the measuring apparatus (G01N27/3274, G01N27/4175 and G01N33/0006 take precedence)} - G01N 27/122: {Circuits particularly adapted therefor, e.g. linearising circuits} - G01N 27/404: Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid {, e.g. Clark-type oxygen sensors} - 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 An impedance in an electrochemical gas sensor can be measured by connecting at least one pin in an integrated circuit to at least one electrode in an electrochemical gas sensor, using a damping capacitor to connect the at least one pin in the integrated circuit to an electrical ground, applying a voltage to the electrochemical gas sensor to provide a bias voltage to at least one electrode in the electrochemical gas sensor, receiving a current from at least one electrode in the electrochemical gas sensor, determining a measured gas amount from the received current, activating a switch located within the integrated circuit to isolate the damping capacitor from the at least one pin in the integrated circuit, and measuring an impedance of the electrochemical gas sensor using an excitation signal while the at least one damping capacitor is isolated from the at least one electrode in the electrochemical gas sensor. ## Claims ### Claim 1 A method of measuring an impedance of an electrochemical gas sensor, the method comprising: connecting at least one pin in an integrated circuit to at least one electrode in an electrochemical gas sensor; using a damping capacitor to connect the at least one pin in the integrated circuit to an electrical ground; applying a voltage to the electrochemical gas sensor to provide a bias voltage to at least one electrode in the electrochemical gas sensor; receiving a current from at least one electrode in the electrochemical gas sensor; determining a measured gas amount from the received current; activating a switch located within the integrated circuit to isolate the damping capacitor from the at least one pin in the integrated circuit; measuring an impedance of the electrochemical gas sensor using an excitation signal while the at least one damping capacitor is isolated from the at least one electrode in the electrochemical gas sensor. ### Claim 2 (depends on 1) The method of claim 1 further comprising then connecting the damping capacitor to the at least one electrode in the electrochemical gas sensor and further operating the electrochemical gas sensor in a gas detection mode ### Claim 3 (depends on 1) The method of claim 1 comprising connecting a first pin of an integrated circuit to a working electrode of the electrochemical gas sensor, connecting a second pin of an integrated circuit to a reference electrode of the electrochemical gas sensor, and connecting a third pin of an integrated circuit to a counter electrode of the electrochemical gas sensor. ### Claim 4 (depends on 3) The method of claim 3 comprising using a first damping capacitor to connect the first pin in the integrated circuit to an electrical ground and using a second damping capacitor to connect the second pin in the integrated circuit to an electrical ground. ### Claim 5 (depends on 4) The method of claim 4 comprising activating a first switch located within the integrated circuit to disconnect the first damping capacitor from the first pin of the integrated circuit and activating a second switch located within the integrated circuit to disconnect the second damping capacitor from the second pin of the integrated circuit. ### Claim 6 (depends on 5) The method of claim 5 comprising activating a third switch located within the integrated circuit to deactivate filter circuitry located within the integrated circuit. ### Claim 7 (depends on 5) The method of claim 5 comprising using a third damping capacitor to connect a first biasing amplifier terminal to an electrical ground and using a fourth damping capacitor to connect a second biasing amplifier terminal to an electrical ground. ### Claim 8 (depends on 7) The method of claim 7 comprising activating a third switch located within the integrated circuit to disconnect the third damping capacitor from the first biasing amplifier terminal and activating a fourth switch located within the integrated circuit to disconnect the fourth damping capacitor from the second biasing amplifier terminal. ### Claim 9 (depends on 8) The method of claim 8 comprising measuring an impedance of the electrochemical gas sensor while the first, second, third, and fourth switches are activated. ### Claim 10 A method of measuring an impedance of an electrochemical gas sensor, the method comprising: isolating at least one damping capacitor from at least one electrode in the electrochemical gas sensor; and measuring an impedance of the electrochemical gas sensor while the at least one damping capacitor is isolated from the at least one electrode in the electrochemical gas sensor. ### Claim 11 (depends on 10) The method of claim 10 further comprising then connecting the damping capacitor to the at least one electrode in the electrochemical gas sensor for operating the electrochemical gas sensor in a gas detection mode. ### Claim 12 (depends on 11) The method of claim 11 comprising disconnecting at least one damping capacitor from bias circuitry used to provide a bias voltage to at least one electrode in the electrochemical gas sensor and then measuring an impedance of the electrochemical gas sensor while the at least one damping capacitor is disconnected from the circuitry. ### Claim 13 (depends on 11) The method of claim 11 further comprising measuring the impedance of the gas sensor using an excitation signal in a frequency range from 0.2 Hz to 200 kHz while the at least one damping capacitor is disconnected from the circuitry. ### Claim 14 A sensor interface circuit for measuring a gas concentration and an impedance of an electrochemical gas sensor, the sensor interface circuit comprising: an integrated circuit including a first pin configured to be connected to a first electrode in the electrochemical gas sensor; a switch located within the integrated circuit, the switch being configured to connect a noise-suppression capacitor from the first electrode to an electrical ground while the integrated circuit is in a gas sensing mode and disconnect the noise-suppression capacitor while the integrated circuit is in an impedance testing mode; and bias circuitry configured to provide a bias voltage to an electrode in the electrochemical gas sensor. ### Claim 15 (depends on 14) The sensor interface circuit of claim 14 wherein the integrated circuit is configured to inject an excitation signal while the noise suppression capacitor is disconnected. ### Claim 16 (depends on 14) The sensor interface circuit of claim 14 wherein the integrated circuit includes a first pin configured to be connected to a working electrode of the electrochemical gas sensor, a second pin configured to connected to a reference electrode of the electrochemical gas sensor, and a third pin configured to be connected to a counter electrode of the electrochemical gas sensor. ### Claim 17 (depends on 16) The sensor interface circuit of claim 16 wherein the integrated circuit includes a first switch configured to connect a first noise-suppression capacitor from the working electrode to an electrical ground while the integrated circuit is in a gas sensing mode and a second switch configured to connect a second noise-suppression capacitor from the reference electrode to an electrical ground while the integrated circuit is in a gas sensing mode ### Claim 18 (depends on 16) The sensor interface circuit of claim 16 wherein the first switch and the second switch are configured to be activated at the same time. ### Claim 19 (depends on 16) The sensor interface circuit of claim 16 wherein the first switch and the second switch are configured to be activated at different times. ### Claim 20 (depends on 16) The sensor interface circuit of claim 16 wherein the integrated circuit includes a third switch configured to deactivate filter circuitry located within the integrated circuit while the integrated circuit is in an impedance testing mode.