Leidenfrost droplet trampolining

Abstract

A liquid droplet dispensed over a sufficiently hot surface does not make contact but instead hovers on a cushion of its own self-generated vapor. Since its discovery in 1756, this so-called Leidenfrost effect has been intensively studied. Here we report a remarkable self-propulsion mechanism of Leidenfrost droplets against gravity, that we term Leidenfrost droplet trampolining. Leidenfrost droplets gently deposited on fully rigid surfaces experience self-induced spontaneous oscillations and start to gradually bounce from an initial resting altitude to increasing heights, thereby violating the traditionally accepted Leidenfrost equilibrium. We found that the continuously draining vapor cushion initiates and fuels Leidenfrost trampolining by inducing ripples on the droplet bottom surface, which translate into pressure oscillations and induce self-sustained periodic vertical droplet bouncing over a broad range of experimental conditions.

Stimuli-responsive surfaces for switchable wettability and adhesion

“…Zhong et al [72] reviewed how surface topography and wettability affected the Leidenfrost effect, with a view to droplet geometry and dynamics. Recently, Graeber et al [73] observed an even more complex motion of royalsocietypublishing.org/journal/rsif J. R. Soc. Interface 18: 20210162 7 droplets on an overheated surface and referred to this as Leidenfrost droplet trampolining.…”

“…For example, the WCA can be reduced by applying an electric field between a conducting droplet and a counter electrode underneath the droplet, which is an electrowetting course without changing the surface structure [28,79]. Previous studies indicated that by changing the applied voltage during electrowetting, the heat-resisting materials can control droplet geometry and dynamic [72,73] royalsocietypublishing.org/journal/rsif J. R. Soc. Interface 18: 20210162…”

Experimental study of liquid droplets impact on powder surface: The application of effective dimensionless parameters in analysis

“…Various impact behaviorse.g., spreading, retraction, rebounding, and splashing-and the resulting crater morphology as well as, liquid marbles have been investigated in detail [8][9][10] . The behaviors of droplets upon impact have been studied comprehensively by experimental [11,12] , theoretical [13,14] , and numerical methods [15] .…”

Autonomous transport and splitting of a droplet on an open surface

“…There are some relevant works in the field. For example, the study on droplet running uphill from Whitesides et al [30], the recent work on jumping or trampolining drops on surface nanostructures [31,32] and on bouncing drops driven by Marangoni stress [33]. Our previous work [15] focused on transporting a droplet on a wettability-confined gradient surface with the primary objective of finding the optimum wettability confinement.…”