Electroosmotic flow in small-scale channels induced by surface-acoustic waves

Surface-acoustic waves (SAWs) induce a time-averaged electroosmotic flow (EOF) in an aqueous electrolyte confined in a narrow channel that may exceed flow actuation via acoustic streaming. For a parallel-plate channel the EOF can be maximized by using two SAWs on both channel walls that have the same frequency but are phase-shifted by 180\ifmmode^\circ\else\textdegree\fi{}. The proposed actuation might be a viable alternative for driving liquid electrolytes through narrow channels, without the need for electric interconnects and electrodes.