Electroosmotic flow(EOF) is widely used to transport and mix fluids in microfluidic chips.Aiming at the parallel-plate microchannel with surface roughness,governing equations describing the EOF were established and the influence of surface roughness and electrical double layer(EDL) on EOF was investigated by using finite element method(FEM).The simulation results indicated that,when the EDL thickness was comparable to 0.3 times of the height of surface roughness,the presence of surface roughness could alter EDL near the surface,and reduce the EOF significantly.When the EDL thickness was much smaller or much greater than the height of surface roughness,EOF was less affected by surface roughness.The relationship between the EOF speed in bulk flow region and the relative EDL thickness was "V-shaped".
