APPROXIMATE MODELS OF INTERDIGITATED ARRAY ELECTRODES FOR EVALUATING STEADY-STATE CURRENTS

Simple models of an interdigitated array electrode (IDA), which is useful as a sensitive amperometric sensor with a rapid response, were proposed on the basis of geometrical deformation of the IDA and a priori determination of current distributions in order to help understand the concept of mass transport. Dimensionless current values for these models were compared with the rigorous values obtained analytically in previous work. A model of the parallel twin electrode was fairly good for wg/(we + wg)< 0.4 when the equivalent interelectrode distance was wg + we/3, where wg is the width of the gap and we is the width of the microband anode or the cathode. A model of concentric semi-circular current lines also provided a good approximation when current lines in the inner semi-circle on the gap were adequately averaged. The model of elliptic current lines by Seddon et al. was examined mathematically and numerically, and the equations were demonstrated not to be satisfied by the Laplace equation or the boundary conditions. However, they provided approximate values within 80% for wg/(we + wg) < 0.5. © 1990.