Experimental Verification of Overlimiting Current by Surface Conduction and Electro-Osmotic Flow in Microchannels
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PhysRevLett.114.114501.pdf
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Author(s)
Nam, Sungmin
Cho, Inhee
Heo, Joonseong
Lim, Geunbae
Bazant, Martin Z.
Moon, Dustin Jaesuk
Sung, Gun Yong
Kim, Sung Jae
Date Issued
March 2015
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Nam, Sungmin, Inhee Cho, Joonseong Heo, Geunbae Lim, Martin Z. Bazant, Dustin Jaesuk Moon, Gun Yong Sung, and Sung Jae Kim. “Experimental Verification of Overlimiting Current by Surface Conduction and Electro-Osmotic Flow in Microchannels.” Physical Review Letters 114, no. 11 (March 2015). © 2015 American Physical Society
Version
Final published version
Abstract
Direct evidence is provided for the transition from surface conduction (SC) to electro-osmotic flow (EOF) above a critical channel depth (d) of a nanofluidic device. The dependence of the overlimiting conductance (OLC) on d is consistent with theoretical predictions, scaling as d[superscript −1] for SC and d[superscript 4 over 5] for EOF with a minimum around d=8 μm. The propagation of transient deionization shocks is also visualized, revealing complex patterns of EOF vortices and unstable convection with increasing d. This unified picture of surface-driven OLC can guide further advances in electrokinetic theory, as well as engineering applications of ion concentration polarization in microfluidics and porous media.
MIT Department
Massachusetts Institute of Technology. Department of Chemical Engineering
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DOI of Published Version
https://doi.org/10.1103/PhysRevLett.114.114501
