Controlling ion transport through nanopores: modeling transistor behavior

Abstract

We present a modeling study of a nanopore-based transistor computed by a mean-field continuum theory (Poisson–Nernst–Planck, PNP) and a hybrid method including particle simulation (Local Equilibrium Monte Carlo, LEMC) that is able to take ionic correlations into account including the finite size of ions. The model is composed of three regions along the pore axis with the left and right regions determining the ionic species that is the main charge carrier, and the central region tuning the concentration of that species and, thus, the current flowing through the nanopore. We consider a model of small dimensions with the pore radius comparable to the Debye-screening length (R_pore/λ_D ≈ 1), which, together with large surface charges provides a mechanism for creating depletion zones and, thus, controlling ionic current through the device. We report the scaling behavior of the device as a function of the R_pore/λ_D parameter. Qualitative agreement between PNP and LEMC results indicates that mean-field electrostatic effects predominantly determine device behavior.