Effects of Faradaic currents on AC electroosmotic flows with coplanar symmetric electrodes

Microelectrodes subjected to AC potentials are usually employed to induce electrolyte flow, commonly known as AC electroosmotic (ACEO) flows. In this work, we apply novel theoretical results for analysing the influence of Faradaic reactions on these flows. Specifically, we choose to analyse the electrokinetic flow induced by a pair of coplanar symmetric microelectrodes, as the simplest microelectrode structure used in experiments. The liquid is assumed to be a 1:1 electrolyte with ions of different diffusivities. For simplicity, in the model only the cations are responsible for the Faradaic reactions while the anions do not react at the electrodes. We show how to use the novel model to numerically obtain the electrokinetic flow induced by the pair of electrodes. A remarkable new prediction of the model is that, for certain values of the parameters, fluid flow can occur in opposite direction to that obtained in the absence of Faradaic reactions.