Directional motion of resonant drops on a hydrophobic ratchet with gradient inclination

Abstract

A hydrophobic ratchet which consisted of teeth with gradient inclination was prepared in this work. The dynamic behaviors of resonant drops on the ratchet were experimentally investigated using a high-speed camera. According to our results, there are four types of behaviors of a resonant drop on the ratchet, including deformation in situ, wriggling, jumping and breaking up. For a wriggling or jumping drop, the drop can move directionally from the big to small inclination area. A new method to manipulate drop motion is proposed through combining the ratchet with vertical mechanical vibration. Moreover, the motion mechanism is presented on the basis of force analysis. Besides, the effects of amplitude, initial position and drop size on the drop acceleration and velocity are also discussed.