Dynamic properties of vibrated drops on a superhydrophobic patterned surface

With the development of micro- and nano-technology, superhydrophobic surfaces with higher apparent contact angle and lower sliding angle have considerable technological potential for various applications such as dewetting and dropwise condensation. In this work, the square-shaped pillars rough surfaces were prepared with the polydimethyl-siloxane substrate using photolithography techniques. The dynamic properties of the droplets were studied on the superhydrophobic patterned surface. By adjusting the frequency and the amplitude of the vertical displacement, we observe droplets bounding from the superhydrophobic surface at a certain frequency and amplitude. For a certain size of droplet, the results show that the vibration amplitude which induces a droplet to bounce off from the superhydrophobic surface at the resonant frequency is remarkably smaller than the detaching amplitudes of neighboring frequencies. In order to verify the analysis, the eigenfrequency of the other size of droplet was compared with its resonant frequency. The experimental results were in accordance with the theoretical analysis. Therefore, a novel method is provided to remove the condensation droplets from the solid surface in order to improve the heat transfer performance.