The electrokinetic microfluidic flow in multi-channels with emergent applicability toward micro power generation

Abstract

In order to elaborate the possible applicability of microfluidic power generation from conceptualization to system validation, we adopt a theoretical model of the electrokinetic streaming potential previously developed for the single channel problem. The ion transport in the microchannel is described on the basis of the Nernst-Planck equation, and a monovalent symmetric electrolyte of LiClO4 is considered. Simulation results provide that the flow-induced streaming potential increases with increasing the surface potential of the microchannel wall as well as decreasing the surface conductivity. The streaming potential is also changed with variations of the electric double layer thickness normalized by the channel radius. From the electric circuit model with an array of microchannels, it is of interest to evaluate that a higher surface potential leads to increasing the power density as well as the energy density. Both the power density and the conversion efficiency tend to enhance with increasing either external resistance or number of channels. If a single microchannel is assembled in parallel with the order of 103, the power density of the system employing large external resistance is estimated to be above 1 W/m3 even at low pressure difference less than 1 bar.