# US 5,344,547 A · Polycrystalline ion selective electrode > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,344,547 A - Document ID: US5344547A - Status: Granted - Kind: A - Application number: 07/999,287 - Filed: 1993-02-18 - Granted: 1994-09-06 - Earliest claimed: 1993-02-18 - Inventors: Yuri G. Vlasov; Yuri E. Ermolenko - Web page: https://patentgrep.com/patent/US5344547A ## CPC - G01N 27/333: Ion-selective electrodes or membranes (glass electrodes G01N27/36) - 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 improved "all solid state" ion selective electrode device comprising a unique sensing element of triple-layer membrane construction. The first sensor layer of the sensing membrane comprising a solid electrolyte composition, the middle layer comprising a mixture of the aforesaid electrolyte composition and finely divided electronic conducting material, and the third contacting layer composed principally of the aforesaid electronic conducting material. The middle layer having a gradient of component concentration such that a substantial amount of the electrolyte composition is presented in the middle layer closest the first sensor layer and a substantial amount of the electronic conducting material is presented in the middle layer closest the third contacting layer. ## Claims ### Claim 1 A polycrystalline membrane for the detection of an ionic species in solution, said membrane comprising: a first sensor layer composed of a solid electrolyte composition possessing ionic conductivity; a second middle layer comprising a mixture of said solid electrolyte composition and an electronic conducting material, whereby said middle layer has a gradient of component concentration such that a greater amount of said electrolyte composition is presented in said middle layer closest said sensor layer than is presented near said third contacting layer, and a greater amount of said electronic conducting material is presented in said middle layer closest said third contacting layer than is presented near said first contacting layer; and a third electrical contacting layer comprising said electronic conducting material. ### Claim 2 (depends on 1) A membrane in accordance with claim 1 wherein said gradient of component concentration is uniform. ### Claim 3 (depends on 1) A membrane in accordance with claim 1, wherein said membrane comprises a ceramic membrane of compressed polycrystalline material. ### Claim 4 (depends on 1) A membrane in accordance with claim 1, wherein said sensor layer has a lower exposed face for contact with said solution. ### Claim 5 (depends on 4) A membrane in accordance with claim 4, wherein said middle layer has upper and lower surfaces and being sandwiched between and in contact with said sensor layer and said third contacting layer. ### Claim 6 (depends on 5) A membrane in accordance with claim 5, wherein said third contacting layer has an upper exposed face in contact with an electrical wire. ### Claim 7 (depends on 5) A membrane in accordance with claim 5, wherein said gradient of concentration is uniform, such that said lower surface of said middle layer is uniformly comprised of said electrolyte composition and the concentration of said electrolyte composition in said middle layer gradually decreases toward said upper surface of said middle layer, and wherein said upper surface of said middle layer is uniformly comprised of said electronic conducting material and the concentration of said material in said middle layer gradually decreases toward said lower surface of said middle layer. ### Claim 8 (depends on 1) A membrane in accordance with claim 1 wherein said electrolyte composition is selective toward a specific ion in said solution. ### Claim 9 (depends on 8) A membrane in accordance with claim 8 wherein said electrolyte composition includes a silver component. ### Claim 10 (depends on 9) A membrane in accordance with claim 9 wherein said silver component is selected from the group consisting of silver sulfide, silver iodide, silver bromide, silver chloride, silver iodide, silver cyanate, Ag.sub.8 HgS.sub.2 I.sub.6 and mixtures thereof. ### Claim 11 (depends on 10) A membrane in accordance with claim 10 wherein said silver component is mixed with a sulfide salt. ### Claim 12 (depends on 11) A membrane in accordance with claim 11 wherein said sulfide salt is selected from the group consisting of copper sulfide, lead sulfide and cadmium sulfide. ### Claim 13 (depends on 10) A membrane in accordance with claim 10 wherein said silver component is mixed with thallium iodide. ### Claim 14 (depends on 13) A membrane in accordance with claim 13 wherein said electrolyte composition is selective for thallium, said composition comprising a mixture of thallium iodide (TlI) and silver iodide (AgI). ### Claim 15 (depends on 14) A membrane in accordance with claim 14 wherein said thallium iodide is provided in the mixture in a amount ranging from 30 to 50% mole percent with the remainder being silver iodide. ### Claim 16 (depends on 15) A membrane in accordance with claim 15 wherein said composition comprises 30% TlI and 70% AgI in mole percentage amounts. ### Claim 17 (depends on 9) A membrane in accordance with claim 9, wherein said electronic conducting material is metallic silver. ### Claim 18 (depends on 17) A membrane in accordance with claim 17, wherein said metallic silver is finely divided ranging from 20 to 50 micrometers in particle size. ### Claim 19 An all solid state ion selective electrode device for the detection of a particular ion species in solution, said device comprising: a polycrystalline membrane having a first sensor layer composed of a solid electrolyte composition possessing ionic conductivity, a second middle layer comprising a mixture of said solid electrolyte composition and an electronic conducting material, and a third electrical contacting layer comprising said electronic conducting material, wherein said middle layer has a gradient of component concentration such that a greater amount of said electrolyte composition is presented in said middle layer closest said sensor layer than is presented near said third contacting layer, and a greater amount of said electronic conducting material is presented in said middle layer closest said third contacting layer than is presented near said first contacting layer. ### Claim 20 (depends on 19) An electrode device in accordance with claim 19, wherein said sensor layer has an exposed lower face for contact with said solution. ### Claim 21 (depends on 20) An electrode device in accordance with claim 20, wherein said membrane is provided within a housing such that only the said lower face of said sensor layer comes into direct contact with said solution upon immersing said housing into said solution. ### Claim 22 (depends on 19) An electrode device in accordance with claim 19, wherein said third contacting layer has an upper exposed face in contact with an electrical wire. ### Claim 23 (depends on 22) An electrode device in accordance with claim 22, wherein said electrical wire is connected to a readout meter. ### Claim 24 (depends on 23) An electrode device in accordance with claim 23, wherein said readout meter is a volt meter. ### Claim 25 (depends on 23) An electrode device in accordance with claim 23, wherein said readout meter is also connected to an external reference electrode.