Actively Controlled Ionic Current Gating in Nanopores

A conical nanopore was developed that allowed the ionic current to be gated by external application of electrical potential. A numerical model of the pore was created in COMSOL to elucidate the mechanism of action in this pore. The model is composed of a conical nanopore geometry with a gold-plated Si3N4 structure and a complete Gouy-Chapman-Stern electrical double layer. The Poisson, NernstPlanck, and Navier-Stokes equations were solved over the axisymmetric model geometry. Overlap in the diffuse layer caused the pore to be ion selective. Biasing the gold layer of the pore created regions of opposing ion selectivity responsible for the non-conducting state of the pore. Current in the conducting state was mediated by electrophoresis with negligible electroosmosis. This study demonstrates a pore whose conductive properties may be externally controlled in real-time.