Capillary Leidenfrost effect

The Leidenfrost effect, best known as the formation of an insulating vapour layer beneath a liquid droplet that delays boiling, offers great potential for droplet manipulation and drag reduction. However, regulating the conventional Leidenfrost effect remains challenging due to the complex liquid dynamics involved. Here we report a behaviour that we term the capillary Leidenfrost effect, which enables stable and sustained solid levitation driven by liquid evaporation. It occurs at a temperature threshold that is below the Leidenfrost point of its droplet counterpart, yet without the need for specialized surface manufacturing techniques. Our structure is composed of periodically arranged capillaries that stabilize the liquid interface, enhance heat conduction and provide liquid storage capacities. The capillary Leidenfrost effect is generic in widely accessible natural materials and metals. Our experiments demonstrate the feasibility of long-distance, sustained self-propulsion and load delivery on a practical scale. This mechanism facilitates potential applications from contactless transportation and drag reduction to extended-distance delivery in harsh environments.