Effect of Induced-Charge Electro-Kinetics on Concentration-Polarization in a Microchannel-Nafion System

TL;DR

This paper demonstrates how induced-charge electro-osmosis (ICEO) can control the diffusion layer in a microchannel-Nafion system, impacting ion transport and offering a new method for managing concentration polarization.

Contribution

It introduces a novel approach using electrode arrays to manipulate the diffusion layer length scale via ICEO and ACEO flows in microfluidic systems.

Findings

ICEO vortices control the diffusion layer size.

Varying electrode spacing adjusts the diffusion layer length.

ACEO flow enhances fluid stirring and ion transport.

Abstract

Induced-charge electro-osmosis (ICEO) is shown to control the length scale of the diffusion layer (DL), which in turn, affects the diffusion limited ion transport through the microchannel-Nafion membrane system. The ICEO vortices form at an interdigitated floating electrode array embedded within a microchannel interfacing a Nafion membrane and stir the fluid, arresting the diffusive growth of the depletion layer. By varying the spacing between the array and the membrane we are able to control the length of the DL. Activating the electrodes results in further enhancement of the fluid stirring due to the emergence of alternating-current electro-osmotic (ACEO) flow on top of the ICEO. Such a new method of controlling the DL with an electrode array is of great importance in many CP related realizations.