Evolution of Streaming Potential in a Finite Length Microchannel
A. Mansouri, S. Bhattacharjee, D.Y. Kwok and L.W. Kostiuk
University of Alberta, CA
microfluidics, streaming potential, simulation
Pressure-driven-flow in a microchannel with charged solid surfaces induces streaming current and streaming potential. Review of the literature, reveals that most of the studies on the microchannels are either for steady state solution or infinite length microchannels cite(rice, nakache, levine, transient, entry}. In the current study, a transient numerical simulation of ion transport leading to the development of a streaming potential across a finite length cylindrical microchannel was considered. The considered problem was analyzed through the coupling of fluid dynamics, electrical field and charge distribution. The solution based on finite element analysis shows the transient development of ionic fluxes, currents, and the streaming potential across the channel. The influence of the entrance and exit effects (i.e., electrokinetic and hydrodynamic) on the evolution of the streaming potential was clearly depicted in this study. In streaming potential analysis, the effects of these two walls are traditionally neglected. It is observed that these walls, particularly the wall at the channel exit, have profound effects on the evolution of the streaming potential and the ion separation behavior. Furthermore, as electrokinetic phenomena can be considered for energy conversion devices and due to advanced micro scale surface modification technologies, which are able to selectively modify the surface charges through various methods, it might be possible to alter the electrical potential difference across the microchannel by selectively imparting different surface charge densities on the exit wall and enhance the microchannel battery performance proposed by Yang et al.
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Nanotech 2005 Conference Program Abstract