Size Effect of Ion Translocation through Nanopore by Molecular Dynamics

Abstract

While the flow rates (in unit of particles/s) of the ions in aqueous solution depend on the cross sections of the channels they pass through, the flux (in unit of particles/(m2s)) is usually independent of them. However, if the diameter of the channel becomes extremely small and comparable to the effective size of the ions, there can be the dependence of the flux on the channel diameter. The finite size effect of solute ions through such small channel is relevant to the physical process of other nanofluidic technologies such as the DNA translocation through nanopore for the sequencing technologies. In this study, we examine the flow of K+ and Cl- ions in water through nanopores made of graphene structure by molecular dynamics method. The results show that there is a transition of zero to nonzero flux when the pore diameter is around the effective size of the ions. Furthermore, there is a dependence of the flux on the nanopore diameter around this regime.