Guided Self-Propelled Leaping of Droplets on a Micro-Anisotropic Superhydrophobic Surface.

By introducing anisotropic micropatterns on a superhydrophobic surface, we demonstrate that water microdroplets can coalesce and leap over the surface spontaneously along a prescribed direction. This controlled behavior is attributed to anisotropic liquid-solid adhesion. An analysis relating the preferential leaping probability to the geometrical parameters of the system is presented with consistent experimental results. Surfaces with this rare quality demonstrate many unique characteristics, such as self-powered, and relatively long-distance transport of microdroplets by "relay" coalescence-induced leaping.