Influence of electrode geometry on the redox switching characteristics of conducting polymers

The dimensions of working electrodes relative to those of conducting polymer films have been found to influence the redox switching characteristics of polymer films. Using microband electrode arrays, the electrodes were operated either altogether as a single electrode or individually as the working electrode, leading to a large difference in the contact area between the electrode and the overlaying polymer film. When the microband electrodes were operated altogether, the voltammetric peak potential was significantly lower and the rate of oxidation was much faster than when the electrodes were operated individually. Each electrode within the array can also be operated individually (i.e. with equivalent contact area) to address the polymer from different positions across the film. An individual electrode located towards the edge of the film gave rise to higher oxidation peak potentials and slower rates of oxidation when compared to an electrode situated towards the centre of the film. Potentiometric measurements of electrodes situated adjacent to the working electrode showed that the rate of the oxidation was controlled by the propagation of the interface between the conducting and insulating phases [1].