Selection of nonequilibrium overlimiting currents: universal depletion layer formation dynamics and vortex instability.
The ion flux dynamics across a straight nanoslot is imaged to understand the nonequilibrium phenomenon of overlimiting current density across a nanoporous membrane. With a slow ac field, an ion-depletion front is generated intermittently from one end of the nanochannel, and a vortex instability first predicted by Rubinstein, Staude, and Kedem [Desalination 69, 101 (1988).10.1016/0011-9164(88)80013-4] is found to arrest the self-similar diffusive front growth. This electrokinetic instability evolves into a stationary interfacial vortex array that specifies the overlimiting current, independent of external stirring or convective flow.
Yossifon
Gilad
G
Department of Chemical and Biomolecular Engineering, Center for Microfluidics and Medical Diagnostics, University of Notre Dame, Notre Dame, Indiana 46556, USA.
Chang
Hsueh-Chia
HC
D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D005465:Fluorocarbon Polymers / Q000737:chemistry; D007473:Ion Channels / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008567:Membranes, Artificial; D018613:Microscopy, Confocal; D008956:Models, Chemical; D049329:Nanostructures / Q000737:chemistry*
D005465:Fluorocarbon Polymers; D007473:Ion Channels; D008567:Membranes, Artificial; C040402:perfluorosulfonic acid