A new dynamic electrochemical transduction mechanism for interdigitated array microelectrodes

Abstract

A dynamic electrochemical transduction mechanism for interdigitated array microelectrodes using an electrical charge pumping method is presented in this paper. In this dynamic transduction mechanism, a charged external capacitor is used as the charge supplier for the electrochemical reaction of the reversible redox species at the interdigitated array electrodes. The charges stored in the capacitor are consumed as the electrochemical reaction current, which causes the capacitor potential decay. The theoretical analysis has shown that the species concentration has a decisive effect on the capacitor potential decay, and therefore the characteristics of the capacitor potential decay are recorded and analyzed to evaluate the concentration of redox species. The new transduction mechanism has the advantages of achieving high sensitivity with small sensor area and simplifying the measurement instrumentation. As a demonstration device, interdigitated array microelectrodes (∼0.2 mm² electrode surface area) have been fabricated and successfully characterized using p-aminophenol as the redox species under this dynamic mechanism. The detection limit of p-aminophenol was calculated to be approximately 4 × 10⁻⁷ M for the sensor with the new dynamic transduction mechanism.