Nanofluidic diode based on branched alumina nanochannels with tunable ionic rectification.

In this work, the synthetic alumina nanochannels with bi-, tri-, and tetra-branched geometry structures exhibited ionic current rectifications with nonlinear I-V curves. Such diode performance of the branched alumina nanochannel is mainly dependent on the cooperative asymmetry of the branched structure and the surface-charge distribution on inner walls. By regulating the geometry, electrolyte pH, and solution concentration, the tunable ionic rectification properties are effectively obtained including both the rectification ratios and the rectifying direction that were deduced from the converted ion selectivity. This nanofluidic diode may open up a new opportunity for the application of the complex nanofluidic devices in contrast to previously reported channels to provide molecular analysis, controlled mass transport, drug release, and various logic gate operations.