Solid/liquid interfacial friction and slip behaviors on roughness surface under applied voltage

The solid/liquid interfacial friction and slip behaviors on roughness surface under applied voltage were studied. Results showed that the slip behaviors of droplets on roughness surface in the unstable region cannot fit by electrowetting equation. The slip distance and directions mainly depended on difference between right and left friction force at the triple contact line, which were caused by the asymmetric roughness of the solid surface. Moreover, microstructures with various heights were used to control the solid/liquid slip behaviors. Results indicated that when the ridges of scratch far higher than surface roughness of the hydrophobic surface, the slip distance increased and slip direction can be controlled. The findings have potential applications in oriented driving of droplets by electric field.