Molecular dynamics study of electric double layer in nanochannel

Abstract

The Electric Double Layer for electroosmotic flow of NaCl aqueous solution in nanochannels is studied numerically in this paper using Molecular Dynamics (MD) approach. For an electrolyte solution flowing in 40 nm nanochannel, two different conditions for charge on channel wall are defined; first the charge on the wall is held as equal to the amount that was previously reported by the experiment when charge dissociation on silicon dioxide wall occurs and second the constant surface charge density on the wall is assumed. The MD based numerical results show great agreement with experimental data for zeta potential in the range of 10−2−10−1 M. The MD simulations show that Debye length decreases as NaCl concentration increases. Moreover the electric conductance and velocity profile in nanochannel could be extracted from MD results. Performance of the MD approach as a most promising numerical method to study electrokinetic phenomena in nanoscale devices is then verified.