Electroosmotic motion of aqueous solution containing Mg++ inside a silicon nanochannel using Molecular Dynamics simulation

Electroosmotic motion of water and Na, Cl and Mg ions within a silicon nanochannel which is applicable in drug delivery and lab-on-a-chip systems is studied in this article using Molecular Dynamics. How reverse flow takes place in presence of Mg++ has not been thoroughly studied in this field, which is done in this paper. The nanochannel is considered as two parallel surfaces made up of silicon. The ultimate aim here is to evaluate the relation between the electroosmotic flow and channel’s surface charge density. Variations in the velocity profile and ion concentration for different surface charge densities are also demonstrated. In low surface charge densities and within the Debye–Hückel flow regime, any increase in surface charge density contributes to an increase in electroosmotic velocity. Having reached to intermediate flow regime boundaries, the flow loses velocity with more surface charge density. This leads to the point that reverse flow can happen due to extremely high surface charge densities, where more surface charge density means more reversed flow velocity. Furthermore, addition of Mg++ ion to water-NaCl solution results in up to 31 percent increase in average velocity of the electroosmotic motion with fixed charge density.