Here we report on the development of a high-efficiency, dual channel-electrode (DCE) generation-collection system and its application for interrogating redox-active surface-adsorbed thin films. DCE systems consist of two electrodes configured on the base of a microfluidic channel. Under flow conditions, an electrochemical reaction can be driven on the upstream generator electrode and the reactants carried by convection to the downstream collector electrode where the reverse reaction occurs. A significant outcome of this report is that simple fabrication techniques can be used to prepare DCE systems that have collection efficiencies of up to 97%. This level of efficiency makes it possible to quantitatively measure the charge associated with redox-active thin films interposed between the generator and collector electrodes. This is important for interrogating redox species that are not in sufficiently close proximity to an electrode to enable direct electron transfer and for measuring thin films adsorbed to insulating surfaces. Examples might include thick self-assembled monolayers, bilayer membranes incorporating redox-active proteins, or, as shown here, redox-active metal oxide thin films. The method is demonstrated by comparing results from this indirect surface interrogation method, obtained using Fe(CN)<sub>6</sub><sup>3-</sup> as a redox probe, and direct electroreduction of Au oxide thin films. These experimental results are further compared to simulations.

High-efficiency generation-collection microelectrochemical platform for interrogating electroactive thin films

249th National Meeting (2015)

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