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Everyday science

Leidenfrost drops race through a maze

09 Sep 2013 Hamish Johnston

In this fantastic video, physics students at the University of Bath in the UK have had some fun with the Leidenfrost effect. This occurs when a liquid drop comes in contact with a hot surface that produces an insulating layer of vapour that keeps the drop from evaporating rapidly. This layer also allows the drop to glide effortlessly over the surface – and that’s where the fun begins.

It turns out that if you replace a smooth surface with the sort of asymmetrical teeth found in a ratchet, the drop will move rapidly in one direction. By using ratchet surfaces to accelerate liquid drops, the team has made the drops move uphill and even follow a predetermined path through a maze.

And if you wonder what would happen if you combined the Leidenfrost effect with the paramagnetic response of a liquid, check out the beautiful image in the article “Levitating drops controlled by fridge magnets”.

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