Electrodiffusioosmosis in a Solid-State Nanopore Connecting Two Large Reservoirs: Optimum Pore Size

Considering emerging modern applications of nanopore-based sensing devices, we model the electrodiffusiophoresis in a charged solid-state nanopore connecting two large reservoirs. Previous analyses are extended for the first time to take account of the effect of ion concentration polarization, an important factor in real sized devices. We show that the relative magnitude of the double layer thickness and the nanopore size plays the key role, yielding profound and interesting results that are important to device design. Both the nanopore radius and its length have an optimum size at which a maximum electrodiffusioosmotic velocity can be achieved. For a fixed nanopore size, an optimum salt concentration is also present. For example, for an aqueous KCl solution if both the radius and the length of a nanopore is smaller than ca. 5 nm, the averaged salt concentration should exceed ca. 0.3 M so that the associated electrodiffusioosmotic velocity is fast enough to decelerate effectively the translocation velocity of an entity (e.g., DNA). Regression relationships correlating the axial liquid velocity at the nanopore center with nanopore radius and length are developed for design purposes.