In the cell culture device shown in Fig. 1, the potential change in the cell culture region was built by the flow of ions. It is thus intriguing to raise the discussion about the roles of ion channels (also called ClC channels) in such externally applied electrical stimulations. At present, the knowledge about the influence of ClC channels on ion flux in the dcEF is still unclear. Vieira et al. have suggested that at corneal wounds an inward ion flux produced by the ClC-2 channel may enhance wound healing,23 probably by way of the electrotaxis effect of the nearby epithelial cells. Nevertheless, the role of the ClC-2 channel in an externally applied dcEF has not been reported yet. Moreover, to the best of our knowledge, the relation between membrane roughness and ClC channels has not been discussed in literature. In the present work, the dcEF could have triggered some cellular responses or have changed the conformation of some proteins in the ClC channel. However, these responses were not manifested in significant changes in membrane roughness, as shown in Fig. 5, where the treatment of a dcEF alone did not cause detectable changes in membrane roughness with the present NIWOP system (of which the height sensitivity is ). In our setup, the externally applied dcEF induced a steady flow that passed alongside the cell membrane without generating concentration gradient across the membrane. With the present result, we could only postulate that the dcEF did impose synergic effects on membrane roughness together with . It is also known that peptides produce cation (such as ) channels on lipid bilayer membranes.5 Therefore, the effect of external dcEFs on could also be related to cations. Obviously, more studies are necessary to correlate the transmembrane ion flux, , and membrane roughness under the stimulation of dcEFs.