Self-propulsion of Leidenfrost droplets on micropillared hot surfaces with gradient wettability

Motion of matter requires application of asymmetric potential. In this work, we explored the self-propulsion of Leidenfrost droplet on hot micropillared surfaces with gradient wettability. The surface fabricated with micropillars displays unidirectional properties. It was found that Leidenfrost droplets on this surface self-propelled from the smaller superficial area of micropillars (SSAM) towards the larger superficial area of micropillars (LSAM). The self-propulsion mechanism is proposed based on the self-rotation of Leidenfrost droplets and the theoretical model is well matched with the experimental findings. (C) 2017 Elsevier B.V. All rights reserved.