How butterflies stay dry

Slightly bumpy surfaces reduce water drops’ contact time

By Meghan Rosen, 11:20 AM November 20, 2013

So much for rain slickers. Slightly bumpy surfaces, like those of butterfly wings, repel water better than completely smooth surfaces do, researchers report November 20 in Nature.

James Bird of Boston University and colleagues dripped water onto silicon wafers with different textures and filmed the droplets’ splashes. Drops of water striking smooth surfaces flattened into a Frisbee shape before bouncing away. But droplets hitting ridged wafers flared into a splatter that skimmed surfaces only ...

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