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Coupling the Leidenfrost effect and elastic deformations to power sustained bouncing

2017; Nature Portfolio; Volume: 13; Issue: 11 Linguagem: Inglês

10.1038/nphys4194

1745-2481

Scott Waitukaitis, Antal Zuiderwijk, Anton Souslov, Corentin Coulais, Martin van Hecke,

Sports Dynamics and Biomechanics

The Leidenfrost effect occurs when an object near a hot surface vaporizes rapidly enough to lift itself up and hover. Although well-understood for liquids and stiff sublimable solids, nothing is known about the effect with materials whose stiffness lies between these extremes. Here we introduce a new phenomenon that occurs with vaporizable soft solids: the elastic Leidenfrost effect. By dropping hydrogel spheres onto hot surfaces we find that, rather than hovering, they energetically bounce several times their diameter for minutes at a time. With high-speed video during a single impact, we uncover high-frequency microscopic gap dynamics at the sphere-substrate interface. We show how these otherwise-hidden agitations constitute work cycles that harvest mechanical energy from the vapour and sustain the bouncing. Our findings unleash a powerful and widely applicable strategy for injecting mechanical energy into soft materials, with relevance to fields ranging from soft robotics and metamaterials to microfluidics and active matter.