Changing nanoslot ion flux with a dynamic nanocolloid ion-selective filter: secondary overlimiting currents due to nanocolloid-nanoslot interaction.
Nanocolloids trapped at the depleted side (anodic) of a fluidic nanoslot entrance are shown to sensitively regulate dc ion transport through the nanoslot, such that a second limiting-overlimiting transition occurs in its nonlinear current-voltage characteristics. The nanocolloids, brought to the entrance by electro-osmosis, are not stationary but are confined to closed circular and toroidal streamlines, driven by a back-pressure corner vortex and an orthogonal electroconvection vortex instability. The transition from the corner vortex to a complex torus with both vortical motions coincides with the first overlimiting transition, while electrostatic interaction of nanocolloids in these vortices with the nanoslot entrance drives the second limiting transition.
Yossifon
Gilad
G
Faculty of Mechanical Engineering, Micro- and Nanofluidics Laboratory, Technion-Israel Institute of Technology, Technion City 32000, Israel.
Chang
Hsueh-Chia
HC