Effects of molecular level surface roughness on electroosmotic flow

Electroosmotic flow is widely used to transport and mix fluids in micro- and nanofluidic systems. Though essentially all surfaces exhibit certain degrees of roughness, the effects of surface roughness on electroosmotic flow is not well-understood. In this paper, we investigate how the electrical double layer and electroosmotic flow are affected by molecular level surface roughness by using molecular dynamics simulations. The simulation results indicate that, when the thickness of the electrical double layer is comparable to the height of surface roughness, presence of sub-nanometer deep concave regions on a rough surface can alter the electrical double layer near the surface, and reduce the electroosmotic flow significantly.