Pumping of liquids with traveling-wave electroosmosis

Net flow of electrolyte induced by a traveling-wave electric potential applied to an array of microelectrodes is reported. Two fluid flow regimes have been observed: at small-voltage amplitudes the fluid flow follows the direction of the traveling wave, and at higher-voltage amplitudes the fluid flow is reversed. In both cases, the flow seems to be driven at the level of the electrodes. The experiments have been analyzed with a linear electroosmotic model based upon the Debye–Huckel theory of the double layer. The electrical problem for the experimental interdigitated electrode array is solved numerically using a truncated Fourier series. The observations at low voltages are in qualitative accordance with the electroosmotic model.