Ionic current through a nanopore three nanometers in diameter.

Ionic current through a 3 nm in diameter nanopore has been investigated using molecular dynamics. Results indicate that the ionic current increases linearly as the electrolyte concentration increases from 0.4 to 0.9 M, beyond which the ionic current increases at a slower rate. In contradiction to the expectation that higher surface charge density will lead to more ions in the nanopore, and therefore, higher ionic current, the ionic current shows an increase-decrease profile as the surface charge density increases. These unusual observations are attributed to the fact that ions close to the wall experience large viscous force, leading to low mobility.