Effects of Electroosmotic Flow on Ionic Current Rectification in Conical Nanopores

The effects of electroosmotic flow (EOF) on the ionic current rectification (ICR) phenomenon in conical nanopores are studied comprehensively with use of a continuum model, composed of Nernst−Planck equations for the ionic concentrations, the Poisson equation for the electric potential, and Navier−Stokes equations for the flow field. It is found that the preferential current direction of a negatively charged nanopore is toward the base (tip) under a relatively high (low) κRt, the ratio of the tip radius size to the Debye length. The direction also changes with the charge polarity of the nanopore. The EOF effect on the ionic current rectification ratio in a conical nanopore becomes noticeable at an intermediate κRt and surface charge density of the nanopore, meanwhile increasing significantly with the applied voltage.