Issue 11, 2018

Enhanced ion transport using geometrically structured charge selective interfaces

Abstract

A microfluidic platform containing charged hydrogels is used to investigate the effect of geometry on charge transport in electrodialysis applications. The influence of heterogeneity on ion transport is determined by electrical characterization and fluorescence microscopy of three different hydrogel geometries. We found that electroosmotic transport of ions towards the hydrogel is enhanced in heterogeneous geometries, as a result of the inhomogeneous electric field in these systems. This yields higher ionic currents for equal applied potentials when compared to homogeneous geometries. The contribution of electroosmotic transport is present in all current regimes, including the Ohmic regime. We also found that the onset of the overlimiting current occurs at lower potentials due to the increased heterogeneity in hydrogel shape, owing to the non-uniform electric field distribution in these systems. Pinning of ion depletion and enrichment zones is observed in the heterogeneous hydrogel systems, due to electroosmotic flows and electrokinetic instabilities. Our platform is highly versatile for the rapid investigation of the effects of membrane topology on general electrodialysis characteristics, including the formation of ion depletion zones on the micro-scale and the onset of the overlimiting current.

Graphical abstract: Enhanced ion transport using geometrically structured charge selective interfaces

Supplementary files

Article information

Article type
Paper
Submitted
14 nov 2017
Accepted
23 feb 2018
First published
17 mei 2018
This article is Open Access
Creative Commons BY-NC license

Lab Chip, 2018,18, 1652-1660

Enhanced ion transport using geometrically structured charge selective interfaces

A. M. Benneker, B. Gumuscu, E. G. H. Derckx, R. G. H. Lammertink, J. C. T. Eijkel and J. A. Wood, Lab Chip, 2018, 18, 1652 DOI: 10.1039/C7LC01220A

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