A new method for evaluating the most-stable contact angle using mechanical vibration

We propose a new method for the direct measurement of the moststable contact angle, using the mechanical vibration of sessile drops from different metastable states. We relaxed sessile drops of identical volume but with different stable contact angles between advancing and receding configurations. Before the vibration, we were able to scan the range of experimentally-accessible drop configurations. In this manner, the most-stable contact angle was experimentally recognized as the observable contact angle unchanged after vibration independent of the previous history (initial state) of the system. We applied this novel strategy to paraffin wax surfaces with a wide range of roughness degree.