Self-Rotation-Induced Propulsion of a Leidenfrost Drop on a Ratchet.

A Leidenfrost drop is capable of self-propelling on a ratchet, which consists of asymmetric teeth. In this work, the corresponding movements were first experimentally investigated. Because the detected motion could not be interpreted using existing propulsive mechanisms, a new propulsive mechanism was then developed, followed by force analysis using a scaling law.