Superhydrophobic surfaces have aroused great attention for promising applications

e.g.

enhanced heat transfer. The rough surface of square-shaped pillars was prepared from the polydimethyl-siloxane (PDMS) substrate by using photolithography technique. Based on the analysis of dynamic wetting characteristics of water droplets during vertical vibration

the Wenzel-Cassie wetting transition on the rough surface was studied with experimental and theoretical techniques. The experimental results showed that the Wenzel state droplets on the square-shaped pillars rough surface could change to the Cassie state when forced vibration frequency and amplitude were in the threshold range. When the eigenfrequency of the droplet was in accordance with forced vibration frequency

that is to say

at the resonance frequency

the forced vibration amplitude for Wenzel-Cassie wetting transition reached the lowest value. When forced vibration frequency was far from eigenfrequency

vibration amplitude was greater than the amplitude corresponding to resonance frequency. In the end

using the theory of surface chemistry

combining with vibration mechanics

a physical model was proposed to explain the Wenzel-Cassie wetting transition mechanism. This study could be potentially used to improve and control the heat transfer performance of dropwise condensation.