Patent ID: 8404096

Claim:
A method for producing highly sensitive potentiometric sensors by coating of electrically conductive electrodes with an electroconductive polymer, which method comprises the steps of: (a) preparing an aqueous solution for electrochemical polymerisation comprising monomeric units of the electroconductive polymer at a concentration in the range of 0.002-0.05M; and a supporting electrolyte, which also serves as a doping agent, at a concentration in the range of 0.0001-0.005M; (b) assembling an electrochemical polymerisation cell comprising the solution for electrochemical polymerisation, an auxiliary electrode, one or more working electrodes to be coated with electroconductive polymer, and optionally a reference electrode; and (c) coating the working electrode(s) with a polymer film by the electrochemical synthesis of polymer from the electrochemical polymerisation solution using at least one of the following electrochemical regimes: (i) applying a cyclic voltage in the range −0.2-+2.0 V vs Ag/AgCl reference electrode between the working electrode(s) to be coated and the auxiliary electrode; (ii) applying a constant current in the single or multiple current steps with given current density in a range 0.01-1 mA/cm 2 between working electrode(s) to be coated and auxiliary electrode for defined period of time such that final quantity of electricity passed through working electrode(s) will lie in a range 10-250 mC/cm 2 ; (iii) applying a constant potential in a single or multiple potential steps at the range 0-3 V between working electrode(s) to be coated and a reference electrode for defined period of time such that final quantity of electricity passed through the working electrode(s) will lie in a range 10-250 mC/cm 2 .