# US 7,611,613 B2 · High temperature total NOx sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,611,613 B2 - Document ID: US7611613B2 - Status: Granted - Kind: B2 - Application number: 11/195,508 - Filed: 2005-08-02 - Published: 2007-02-08 - Granted: 2009-11-03 - Earliest claimed: 2005-08-02 - Assignees: The Ohio State University Research Foundation - Inventors: Prabir K. Dutta; Jiun-Chan Yang - Web page: https://patentgrep.com/patent/US7611613B2 ## CPC - G01N 27/4074: {for detection of gases other than oxygen} - G01N 27/4077: {Means for protecting the electrolyte or the electrodes} - G01N 33/0037: {NOx} - Y02A 50/20: Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters - 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) - Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE ## Abstract A total NOx sensor with minimal interferences from CO and O2 includes a yttria-stabilized zirconia (YSZ) pellet and a Pt-loaded zeolite Y layer. Furthermore, three platinum wires are attached to the YSZ surface which operate as the working, counter and reference electrode. A potentiostat is connected to the electrodes to maintain a fixed potential between the reference and working electrode. The potentiostat then monitors the relationship between time and current through the counter electrode. ## Claims ### Claim 1 An amperometric sensor for simultaneously measuring NO and NO2 contained in a gas flowing through a conduit comprising: a YSZ pellet having a first surface, to be contacted by the gas during operation of the sensor; a reference electrode electrically connected to and disposed on the first surface; a counter electrode electrically connected to and disposed on the first surface; a working electrode electrically connected to and disposed on the first surface; a catalytic filter disposed upstream of the first surface; and an electrical device operable to apply a constant positive or negative voltage between the reference electrode and the working electrode while the gas contacts the first surface, the electrical device operable to measure current flowing through the counter electrode while the gas contacts the first surface, wherein operation of the sensor does not require a temperature difference between the catalytic filter and the YSZ pellet. ### Claim 2 (depends on 1) The sensor of claim 1 wherein the catalytic filter and said the YSZ pellet are maintained within the same temperature range. ### Claim 3 (depends on 2) The sensor of claim 2 wherein the temperature range is between 300-700° C. ### Claim 4 (depends on 2) The sensor of claim 2 wherein the temperature range is between 450-600° C. ### Claim 5 (depends on 1) The sensor of claim 1 wherein the catalytic filter is disposed over the electrodes and on the first surface. ### Claim 6 (depends on 1) The sensor of claim 1 wherein the catalytic filter is a Pt-loaded zeolite Y filter. ### Claim 7 (depends on 1) The sensor of claim 1 wherein the catalytic filter is a Pt-loaded silica Y filter. ### Claim 8 (depends on 1) The sensor of claim 1 wherein the catalytic filter is a Pt-loaded alumina filter. ### Claim 9 (depends on 1) The sensor of claim 1 wherein the catalytic filter is Pt-loaded in a range of 0.1 to 10 wt %. ### Claim 10 (depends on 1) The sensor of claim 1 wherein the electrical device is a potentiostat. ### Claim 11 An automobile comprising: a combustion engine having an exhaust conduit; an amperometric sensor for simultaneously measuring NO and NO2 contained in a gas flowing though the exhaust conduit comprising: a YSZ pellet having a first surface to be contacted by the gas during operation of the sensor; a reference electrode electrically connected to and disposed on the first surface; a counter electrode electrically connected to and disposed on the first surface; a working electrode electrically connected to and disposed on the first surface; a catalytic filter disposed upstream of the first surface; and an electrical device operable to apply a constant positive or negative voltage between the reference electrode and the working electrode while the gas contacts the first surface, the electrical device operable to measure current flowing through the counter electrode while the gas contacts the first surface, wherein operation of the sensor does not require a temperature difference between the catalytic filter and the YSZ pellet. ### Claim 12 (depends on 11) The automobile of claim 11 wherein the catalytic filter and the YSZ pellet are maintained within the same temperature range. ### Claim 13 (depends on 12) The automobile of claim 12 wherein the temperature range is between 300-700° C. ### Claim 14 (depends on 13) The automobile of claim 13 wherein the temperature range is between 450-600° C. ### Claim 15 (depends on 11) The automobile of claim 11 wherein the catalytic filter is disposed over the electrodes and on the first surface. ### Claim 16 (depends on 11) The automobile of claim 11 wherein the catalytic filter is a Pt-loaded zeolite Y filter. ### Claim 17 (depends on 11) The automobile of claim 11 wherein the electrical device is a potentiostat. ### Claim 18 (depends on 11) The automobile of claim 11 wherein the electrical device includes feedback to control air/fuel mixture for optimal combustion, minimizing emissions and monitoring NO and NO2 after treatment systems. ### Claim 19 A method of simultaneously measuring NO and NO2 contained in a gas flowing through a conduit comprising the steps of: conducting the gas through an amperometric sensor, the sensor comprising: a YSZ pellet having a first surface to be contacted by the gas during operation of the sensor; a reference electrode electrically connected to and disposed on the first surface; a counter electrode electrically connected to and disposed on the first surface; a working electrode electrically connected to and disposed on the first surface; a Pt-loaded zeolite Y filter disposed upstream of the first surface; and an electrical device operable to apply a constant positive or negative voltage between the reference electrode and the working electrode while the gas contacts the first surface, the electrical device operable to measure current flowing through the counter electrode while the gas contacts the first surface, wherein operation of the sensor does not require a temperature difference between the catalytic filter and the YSZ pellet; measuring the current while the gas contacts the sensor; and multiplying the measured current by a calibration constant to measure the amount of NO and NO2. ### Claim 20 (depends on 19) The method of claim 19 wherein said Pt-loaded zeolite Y filter and said YSZ pellet are maintained within the same temperature range. ### Claim 21 (depends on 19) The method of claim 19 wherein the Pt-loaded zeolite Y filter is disposed over the electrodes and on said first surface. ### Claim 22 (depends on 20) The method of claim 20 wherein the temperature range is between 300-700° C.