Ionic Transport in Finite Length Nano-Sized Pores and Channels

Surface-charge regulated ionic transport phenomena in nano-pores and nano-channels have important applications in bio molecular analyses and power conversion involving NEMS. In such devises, the surface-to-volume ratio increases significantly. In nanofluidics, one characteristic is the overlapping of the electrical double layer (EDL) and the disappearance of the electrically neutral zone. The configuration to be considered is a finite length nano pore/channel connected by two reservoirs. Multi-dimensional analyses based on solutions of the Poisson-Nernst-Planck (PNP) equation were performed for the configuration in this study. Numerical solutions show that the ionic transport process in such a configuration depends strongly on the liquid-solid interface models used. These interface models usually serve as wall boundary conditions in multi-dimensional numerical analyses. Most current models were derived based on 1-D fully developed analyses. Issues regarding the extension of the surface chemical equilibrium model to multi-dimensional nanofluidics simulations involving overlapping EDLs were investigated and discussed in this paper.