(288a) Electro-Osmosis at Liquid-Liquid Interfaces

The vast majority of work on electrokinetics has involved flows over solid/liquid interfaces. Less-well studied are flows at liquid-liquid interfaces. In some cases, the electrophoretic mobility of liquid drops has been observed to be orders of magnitude higher than similarly-charged solid particles; in other cases no such discrepancy arises. Here we discuss electro-osmotic flows over liquid-liquid interfaces, clearly identifying the fundamental mechanisms behind these dramatic enhancements and elucidating the enhanced role played in such systems by other physical effects. We discuss these effects in the context of microfluidic applications, -- paying particular emphasis to induced-charge electro-osmotic (ICEO) flows. We discuss multi-order-of-magnitude increases possible for ICEO flows and the effects that ultimately limit them, as well as methods to allow strong ICEO flows to be driven even under highly-conductive fluids.