Overlimiting current in a microchannel

E. Victoria Dydek, Boris Zaltzman, Isaak Rubinstein, D. S. Deng, Ali Mani, Martin Z. Bazant

Research output: Contribution to journalArticlepeer-review

212 Scopus citations


We revisit the classical problem of diffusion-limited ion transport to a membrane (or electrode) by considering the effects of charged sidewalls. Using simple mathematical models and numerical simulations, we identify three basic mechanisms for overlimiting current in a microchannel: (i) surface conduction carried by excess counterions, which dominates for very thin channels, (ii) convection by electro-osmotic flow on the sidewalls, which dominates for thicker channels, and (iii) transitions to electro-osmotic instability on the membrane end in very thick channels. These intriguing electrokinetic phenomena may find applications in biological separations, water desalination, and electrochemical energy storage.

Original languageEnglish
Article number118301
JournalPhysical Review Letters
Issue number11
StatePublished - 6 Sep 2011

ASJC Scopus subject areas

  • Physics and Astronomy (all)


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