# US 9,005,983 B2 · Electro-chemical sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,005,983 B2 - Document ID: US9005983B2 - Status: Granted - Kind: B2 - Application number: 13/062,788 - Filed: 2009-08-26 - Published: 2012-03-15 - Granted: 2015-04-14 - Earliest claimed: 2008-09-08 - Assignees: Schlumberger Technology Corporation - Applicants: Kay McGuinness; Nathan Lawrence; Andrew Meredith - Inventors: Kay McGuinness; Nathan Lawrence; Andrew Meredith - Web page: https://patentgrep.com/patent/US9005983B2 ## CPC - G01N 33/24: Earth materials (G01N33/42 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 The present invention provides an electrochemical sensor having a solid electrically conductive substrate and a compound immobilized thereon which has binding affinity for an analyte species to be detected and also displays electrochemical behavior which is modified upon binding of that analyte species, so that binding of an analyte species can be detected by measuring electrochemical properties, such as by voltammetry. Desirably the immobilized compound contains both a first moiety with binding affinity for the analyte and a separate second moiety which is a redox system whose electrochemical oxidation/reduction properties become modified when the first moiety binds the analyte. The analyte binding moiety may be a diol or polyol and preferably is a sugar. The electrochemical sensor finds use in methods of analyzing reservoir and process fluids, particularly at a subterranean location. The electrochemical sensor may be a component of a downhole tool, adapted for deployment downhole. ## Claims ### Claim 1 A method of detecting an analyte species in a liquid, the analyte species being selected from ions of the non-metal B and ions of the metals Cu, Fe, Co, Ni, Ba, Ca, Sr, Mo, W, Zn, Cd, Hg, Mg, Ra, Pb, Pd, Pt, and V, the method comprising: providing an electrochemical sensor comprising: a solid electrically conductive substrate and at least one compound immobilized thereon which contains both a sugar which is a di- or poly-hydroxy compound with binding affinity for the analyte species to be detected and a non-sugar redox system which displays electrochemical oxidation/reduction behaviour which is modified when the sugar binds the analyte species to be detected, wherein the sugar and the non-sugar redox system are connected directly or indirectly through one or more covalent bonds contacting the liquid with the sensor, for binding of the analyte to the said compound immobilized on the substrate, and measuring the electrochemical oxidation/reduction behaviour of the redox system of said compound immobilized on the substrate. ### Claim 2 (depends on 1) A method according to claim 1 wherein measurement of the electrochemical oxidation/reduction behaviour of the redox system of the said immobilised compound is carried out by voltammetry. ### Claim 3 (depends on 1) A method according to claim 1 wherein the ionic analyte species is selected from ions of the metals Ca, Mg, Ba, Sr, Ra and Fe. ### Claim 4 (depends on 1) A method according to claim 1 wherein the sugar has a five or six membered carbohydrate ring. ### Claim 5 (depends on 1) A method according to claim 1 wherein the sugar has a five or six membered carbohydrate ring with modifications to one, two or three of the hydroxyl groups of the carbohydrate ring. ### Claim 6 (depends on 1) A method according to claim 1 wherein the liquid is a subterranean water body and the sensor is incorporated in a tool suspended in a well communicating with the subterranean water body. ### Claim 7 (depends on 1) A method according to claim 1 wherein the liquid is in a wellbore and the sensor is in a tool suspended in the wellbore. ### Claim 8 (depends on 1) A method according to claim 1 wherein the tool is a wireline tool or a slickline tool. ### Claim 9 (depends on 1) A method according to claim 1 wherein the redox system undergoes electrochemical oxidation and reduction reactions in aqueous solution, and properties of the reactions are altered when the sugar binds the analyte. ### Claim 10 (depends on 9) A method according to claim 9 wherein voltages at which maximum redox reaction occurs are altered when the first moiety binds the analyte and measurement of the electrochemical oxidation/reduction behaviour of the redox system of the said immobilised compound is carried out by voltammetry. ### Claim 11 A method of detecting an ionic analyte species in a liquid, the analyte species being selected from ions of the non-metal B and ions of the metals Ca, Cu, Fe, Co, Ni, Ba, Ca, Sr, Mo, W, Zn, Cd, Hg, Mg, Ra, Pb, Pd, Pt, and V, the method comprising: providing an electrochemical sensor comprising: a solid electrically conductive substrate and at least one compound immobilized thereon which has binding affinity for an ionic analyte species to be detected and displays electrochemical oxidation/reduction behaviour which is modified upon binding of the analyte, wherein the compound contains both a first moiety with binding affinity for the analyte and a second moiety which is a redox system connected to the first moiety through one or more covalent bonds and whose electrochemical oxidation/reduction properties become modified when the first moiety binds the analyte, contacting the liquid with the sensor, for binding of the analyte to the said compound immobilized on the substrate, and measuring the electrochemical oxidation/reduction behaviour of the redox system of the said compound immobilized on the substrate. ### Claim 12 (depends on 11) A method according to claim 11 wherein measurement of the electrochemical oxidation/reduction behaviour of the redox system of the said immobilised compound is carried out by voltammetry. ### Claim 13 (depends on 11) A method according to claim 11 wherein the ionic analyte species is selected from ions of the metals Ca, Mg, Ba, Sr, Ra and Fe. ### Claim 14 (depends on 11) A method according to claim 11 wherein the conductive substrate is carbon-based. ### Claim 15 (depends on 11) A method according to claim 11 wherein the redox system displays electrochemical oxidation and reduction when in contact with aqueous solution having pH in the range from pH 4 to pH 10. ### Claim 16 (depends on 11) A method according to claim 11 wherein the redox system is a metallocene. ### Claim 17 (depends on 11) A method according to claim 11 wherein the liquid is a subterranean water body and the sensor is incorporated in a tool suspended in a well communicating with the subterranean water body. ### Claim 18 (depends on 11) A method according to claim 11 wherein the redox system undergoes electrochemical oxidation and reduction reactions in aqueous solution, and properties of the reactions are altered when the first moiety binds the analyte. ### Claim 19 (depends on 18) A method according to claim 18 wherein voltages at which maximum redox reaction occurs are altered when the first moiety binds the analyte and measurement of the electrochemical oxidation/reduction behaviour of the redox system of the said immobilised compound is carried out by voltammetry. ### Claim 20 (depends on 11) A method according to claim 11 wherein the liquid is in a wellbore and the sensor is in a tool suspended in the wellbore. ### Claim 21 (depends on 20) A method according to claim 20 wherein the tool is a wireline tool or a slickline tool.