Evolution of Streaming Potential in a Finite Length MicroChannel

摘要

Electrokinetic (EK) flow, i.e., flow of an electrolyte in narrow capillaries driven by the combined influence of electric field and pressure, is of significant interest in mi-crofluidic devices. Review of literature reveals that most studies on microchannels are either for steady state conditions or infinite length microchannels. In this work, we examine the development of a transient streaming potential for pressure-driven EK flow in a finite length microchannel. A transient numerical simulation of ion transport leading to the development of a streaming potential across a finite length circular cylindrical microchannel connecting two infinite reservoirs is presented. The solution based on finite element analysis shows the transient development of ionic fluxes, currents, and the streaming potential across the channel. The simulation results show that the streaming potential across the channel is predominantly set up at the timescale of the developing convective transport, while the equilibrium ion concentrations are developed over a considerable longer duration.