image: Successive positions of a self-propelled ethanol drop on a cryogenic bath. view more
Credit: Image courtesy of Anaïs Gauthier.
Droplets levitated above a cryogenic liquid can spontaneously self-propel across the surface in a straight line, a study finds. Volatile liquid drops on a sufficiently hot solid can hover above the surface on a cushioning layer of their own vapor. This phenomenon is known as the Leidenfrost effect, and drops levitated in this manner are free from the constraints of friction to glide, bounce, and oscillate across the surface. Anaïs Gauthier and colleagues investigated an inverse Leidenfrost scenario, in which oil droplets at room temperature levitate above a cryogenic liquid on vapor generated by the bath. The authors demonstrate that ethanol and silicone oil droplets, initially at rest on a pool of liquid nitrogen, begin to self-propel after a few seconds, gliding in a straight line until disrupted by interactions with the edge of the container. In addition, the self-propulsion persists even after the droplets freeze and cool to the temperature of liquid nitrogen, lasting for 10 minutes or longer. According to the authors, this motion is driven by an asymmetry between the front and back of the drop that emerges in the thickness of the supporting film.
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Article #18-12288: "Self-propulsion of inverse Leidenfrost drops on a cryogenic bath," by Anaïs Gauthier, Christian Diddens, Rémi Proville, Detlef Lohse, and Devaraj van der Meer
MEDIA CONTACT: Anaïs Gauthier, University of Twente, Enschede, NETHERLANDS; e-mail: a.e.gauthier@utwente.nl
Journal
Proceedings of the National Academy of Sciences