Electrooxidation of Hexacyanoferrate(II) Anions and Electroreduction of Oxygen in the Microfabricated Electrochemical Sensor-Array System

Abstract

The microfabrication technique was used to prepare a six-channel sensor-array chip. The sensor-array has been fabricated using borosilicate wafer containing Pt electrodes and connection pads and the silicon wafer with through holes, which were bonded with SU-8 using adhesion bonding method. To characterize the prepared sensor-array chips the cyclic voltammetry and electrochemical impedance experiments were carried out in a three-electrode electrochemical system. The electrooxidation of ferrocyanide and electroreduction of oxygen were studied. It was shown that the measured current density depends on the electrode potential sweep rate however, both linear and radial diffusion mass transfer components are important at high electrode potential scanning rate. The pseudo steady-state conditions were achieved at slow potential sweep rates (>0.01 V s‒1) and the electrodes behaved as the microelectrodes. The pseudo steady-state current density is proportional to the concentration of electroactive species. The recessed microdisc electrode model has been used to describe the system.