Depletion of Electroactive Species in Microchannels. Theory and Experimental Validations for Quantitative Abatement of Interfering Species under Stagnant Conditions

Abstract

The generation of an electroactive-species depleted microenvironment was investigated by taking advantage of confinement in microchannels under stagnant conditions. High depletion rates can be achieved with paired microband electrodes but the time scale of experiment must be carefully delimited based on device geometry, electrochemical cell configuration and species diffusivity. Numerical simulations were thus carried out to reach the situation of interest when the diffusion coupling and lateral diffusion in the microchannel becomes predominant with the operation of the electrodes. The optimal conditions for two minimal cell configurations (i.e., with two or three working electrodes) were delineated by establishing a zone diagram. Experimental validations were successfully performed (i) to illustrate the depletion rate achieved between two side electrodes, and (ii) to demonstrate the selective detection of a target analyte in presence of interfering species by using three electrodes. These situations can easily be extrapolated to the case of regular microelectrode arrays within microchannels.