# US 5,344,549 A · Oxygen partial pressure sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,344,549 A - Document ID: US5344549A - Status: Granted - Kind: A - Application number: 08/022,593 - Filed: 1993-02-17 - Granted: 1994-09-06 - Earliest claimed: 1991-10-11 - Assignees: The United States of America as represented by the United States Department of Energy - Inventors: Dennis W. Dees - Web page: https://patentgrep.com/patent/US5344549A ## CPC - G01N 27/4075: {Composition or fabrication of the electrodes and coatings thereon, e.g. catalysts} - G01N 27/407: for investigating or analysing gases {(G01N27/411 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 A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. ## Claims ### Claim 1 An oxygen partial pressure sensor comprising: a solid electrolyte having a first surface and a second surface; an oxygen permeable porous electrode, acting as a cathode, having an exhaust stream side and an electrolyte side, wherein the electrolyte side of said oxygen permeable porous electrode contacts the first surface of said solid electrolyte and entirely covers mid first surface; an oxygen impermeable nonporous electrode, acting as an anode, contacting the second surface of said solid electrolyte and entirely covering said second surface; oxygen impermeable insulator means cooperating with said oxygen permeable porous electrode and said oxygen impermeable nonporous electrode and surrounding said solid electrolyte so as to allow essentially only the first surface of said solid electrolyte contacting said oxygen permeable porous electrode to be exposed to an exhaust stream such that a flow of oxygen ions through the solid electrolyte is essentially blocked; means for applying a voltage across said electrodes; and means for sensing a flow of current between said electrodes. ### Claim 2 (depends on 1) An oxygen partial pressure sensor as recited in claim 1 wherein said solid electrolyte is a ceramic oxide. ### Claim 3 (depends on 2) An oxygen partial pressure sensor as recited in claim 2 wherein said ceramic oxide is selected from the group consisting of ZrO.sub.2, ThO.sub.2, CeO.sub.2, HfO.sub.2 and combinations thereof. ### Claim 4 (depends on 1) An oxygen partial pressure sensor as recited in claim 1 wherein said electrolyte has a minimum thickness of about 0.01 .mu.m and a maximum thickness of about 100 .mu.m. ### Claim 5 (depends on 1) An oxygen partial pressure sensor as recited in claim 1 wherein said exhaust stream side of said oxygen permeable porous electrode is coated with a spinel compound. ### Claim 6 (depends on 5) An oxygen partial pressure sensor as recited in claim 5 wherein the thickness of said spinel compound is between approximately 10 .mu.m and 100 .mu.m. ### Claim 7 (depends on 5) An oxygen partial pressure sensor as recited in claim 5 wherein said spinel compound has the following general formula: M"M.sub.2 "'O.sub.4 wherein M" is magnesium, zinc, manganese, or ferrous iron and M"' is aluminum, chromium, ferric iron, or manganese. ### Claim 8 (depends on 5) An oxygen partial pressure sensor as recited in claim 5 wherein the thickness of said oxygen permeable porous electrode is less than 0.2 times the thickness of the spinel coating. ### Claim 9 (depends on 1) An oxygen partial pressure sensor as recited in claim 1 wherein said means for applying a voltage across said electrodes is maintained at a specific voltage. ### Claim 10 An oxygen partial pressure sensor comprising: a substantially flat solid electrolyte having a first and a second surface; an oxygen permeable porous electrode, acting as a cathode, having an exhaust stream side and an electrolyte side, wherein the electrolyte side of said oxygen permeable porous electrode contacts the first surface of said solid electrolyte; an oxygen impermeable nonporous electrode, acting as an anode, contacting the second surface of said solid electrolyte; means for applying a voltage across said electrodes; and means for sensing a flow of current between said electrodes; wherein said oxygen permeable porous electrode covers the entire first surface of said solid electrolyte; wherein said oxygen impermeable nonporous electrode covers the entire second surface of said solid electrolyte; and wherein said solid electrolyte is thin so as to allow essentially only the first surface of said solid electrolyte to be exposed to an exhaust stream; such that a flow of oxygen ions through the solid electrolyte is essentially blocked. ### Claim 11 (depends on 10) An oxygen partial pressure sensor as recited in claim 10 wherein said solid electrolyte is a ceramic oxide. ### Claim 12 (depends on 10) An oxygen partial pressure sensor as recited in claim 10 wherein said ceramic oxide is selected from the group consisting of ZrO.sub.2, ThO.sub.2, CeO.sub.2, HfO.sub.2 and combinations thereof. ### Claim 13 (depends on 10) An oxygen partial pressure sensor as recited in claim 10 wherein said solid electrolyte has a minimum thickness of about 0.01 .mu.m and a maximum thickness of about 100 .mu.m. ### Claim 14 (depends on 10) An oxygen partial pressure sensor as recited in claim 10 wherein said exhaust stream side of said oxygen permeable porous electrode is coated with a spinel compound. ### Claim 15 (depends on 14) An oxygen partial pressure sensor as recited in claim 14 wherein the thickness of said spinel compound is between approximately 10 .mu.m and 1000 .mu.m. ### Claim 16 (depends on 14) An oxygen partial pressure sensor as recited in claim 14 wherein said spinel compound has the following general formula: M"M.sub.2 "'O.sub.4 wherein M" is magnesium, zinc, manganese, or ferrous iron and M"' is aluminum, chromium, ferric iron, or manganese. ### Claim 17 (depends on 14) An oxygen partial pressure sensor as recited in claim 14 wherein the thickness of said oxygen permeable porous electrode is less than 0.2 times the thickness of the spinel coating. ### Claim 18 (depends on 14) An oxygen partial pressure sensor as recited in claim 14 wherein said means for applying a voltage across said electrodes is maintained at a specific voltage.