Nonlinear current-voltage characteristics of nanochannels.
Like ion channels, nanochannels are known to exhibit curious non-Ohmic current-voltage (I-V) characteristics with an approximate piece-wise constant differential resistance. Using a nanoslot model and a nonequilibrium ion transport theory, we attribute the nonlinear resistance to overlapping double layers inside and an extended polarized layer of space charge outside the nanochannel. The overlimiting current beyond a critical voltage is shown to develop when the polarized layer is destabilized by a microvortex instability at one entrance. By extending earlier nanochannel and polarized layer models to include this instability, nonideal ion permselectivity and field-focusing effect, quantitative predictions-together with explicit differential resistance expressions-are offered for the nonlinear I-V features of a nanochannel surrounded by microreservoirs from a simple pseudo-one-dimensional model.
Yossifon
Gilad
G
Department of Chemical and Biomolecular Engineering, Center for Microfluidics and Medical Diagnostics, University of Notre Dame, Notre Dame, Indiana 46556, USA.
Mushenheim
Peter
P
Chang
Yu-Chen
YC
Chang
Hsueh-Chia
HC