An accurate microdisc simulation model for recessed microdisc electrodes

This study concentrates on an accurate determination of the chronoamperometric response for shallow and deep recessed microdiscs. Diffusion to the recessed microdisc is simulated using the finite element method (FEM). The deviation of the chronoamperometric response for a recessed microelectrode from that for the corresponding inlaid microelectrode can be significant depending on the recess depth. This is noted in terms of the magnitude of the chronoamperometric response and the shape of the chronoamperometric curves. We find cottrellian current decay for deep recess microdiscs at short times "switching" to steady-state behaviour at long times. This switch over in behaviour becomes sharper as the depth of the recess increases. The deviation of the recessed microdisc response from previously proposed approximate expressions is also discussed, with emphasis on the significant deviations for shallow recess microdiscs. The simulation model developed here is accurate yielding transient and steady state values. Approximate analytical expressions which can be used to calculate the transient and steady state responses for recessed microdisc electrodes are presented. (C) 1998 Elsevier Science S.A. All rights reserved.