Streaming potential analysis and electrokinetic energy conversion efficiency of two immiscible fluids in a nanochannel

Abstract

In order to conduct extensive investigation of electrokinetic energy conversion in nanofluidic devices, the analysis of streaming potential of pressure driven flow in the two-layer fluidic system through a nanochannel is investigated theoretically. Under the influences of the interfacial electric potential difference and the interface charge density jump, we first obtain the analytical electric potential distribution in the present two-layer fluidic system with consideration of Debye–Hückel linearization assumption. Then the analytical expressions of streaming potential field and flow velocity are derived. Based on the obtained the streaming potential, we finally give the analytical electrokinetic energy conversion efficiency in two-layer fluidic system and discuss the influences of related physical parameters on it. The theoretical result shows that the streaming potential can be viewed as a criterion to estimate the electrokinetic energy conversion efficiency. The electrokinetic energy conversion efficiency can be enhanced by the viscosity ratio and the interfacial slip length, but be restrained by the permittivity ratio and ion friction coefficient. Comparing to the single-layer fluidic system, the electrokinetic energy conversion efficiency can be augmented obviously in the two-layer fluidic system by selecting optimized flow parameters.