Extended space charge near non-ideally selective membranes and nanochannels

TL;DR

This paper investigates how selectivity variations influence the structure of extended space charge near non-ideal membranes and nanochannels, using analytic and numerical models to understand resistance behavior in electro-diffusive systems.

Contribution

It introduces a combined analytic and numerical approach to analyze the impact of selectivity on extended space charge in micro-nanochannel interfaces.

Findings

Identifies the role of selectivity variation in space charge structure.

Explains the resistance-voltage maximum in micro-nanochannel devices.

Connects geometry and surface charge to control of selectivity and resistance.

Abstract

We demonstrate the role of selectivity variation in the structure of the non-equilibrium extended space-charge using 1D analytic and 2D numerical Poisson-Nernst-Planck models for the electro- diffusive transport of a symmetric electrolyte. This provides a deeper understanding of the underly- ing mechanism behind a previously-observed maximum in the resistance-voltage curve for a shallow micro-nanochannel interface device [Schiffbauer, Liel, Leibowitz, Park, and Yossifon, submitted to Phys. Rev. E.]. The current study helps to establish a connection between parameters such as the geometry and nanochannel surface-charge and the control of selectivity and resistance in the over-limiting current regime.