Understanding Mass Transport at Channel Microband Electrodes: Influence of Confined Space under Stagnant Conditions

Mass transport at channel microband electrodes was investigated theoretically and experimentally under stagnant conditions, both in chronoamperometry and cyclic voltammetry. Under these conditions, the influence of channel height and electrode aspect ratio on diffusion is significant leading to several transient regimes. According to the device geometry and time scale of experiments, a broad range of conditions was considered theoretically. For both electrochemical methods, zone diagrams were established in order to delineate mass transport regimes and associated transitions. Comparison between diagrams showed a drastic influence of spatial constraints onto mass transport depending on the method. Experimental measurements were performed with microdevices having different geometries. A good agreement was observed between theoretical and experimental data validating a posteriori all the simulations. The zone diagrams constitute key tools for predicting and performing accurate electrochemical measurements within the confined space of microchannels.

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