Patent ID: 8784640

Claim:
A method for measuring the content of an oxidation reduction substance dissolved in a liquid, comprising the step of: measuring the content of an oxidation reduction substance dissolved in a liquid using, with a fixed potential, at least one amperometric electrochemical sensor comprising an insulating substrate, a set of electrodes, the set of electrodes including a working electrode, a counter electrode and a reference electrode, the working electrode having a top surface with a periphery edge, at least one of said working electrode and counter electrode being located on a top surface of said insulating substrate, and an insulating layer comprising insulating material extending over the top surface of the insulating substrate, the insulating layer covering said working electrode, wherein said insulating layer completely covers the periphery edge of the top surface of said working electrode, wherein said insulating layer comprises plural openings exposing portions of the top surface of said working electrode, said openings being separated by small islands of the insulating material located on the top surface of said working electrode, and wherein the portions of the top surface of the working electrode exposed by said openings and the small islands on the working electrode are completely covered with at least a first polymer filtration membrane, the first polymer filtration membrane having a selectivity to said dissolved oxidation reduction substance to be measured and defining a diffusion layer for said oxidation reduction substance.