Shrinkage Department

Nano-grass

by Lucent Technologies Inc./Bell Labs
Lucent Technologies Inc./Bell Labs

Water take heed: Liquids are now at the mercy of a breakthrough material from Bell Labs. Flip an electric switch and the material acts like a sponge. Flip again and it behaves like a rain slicker. Applications could turn up wherever liquids meet solids (read: practically everywhere). Lead researcher Tom Krupenkin envisions near-frictionless torpedoes, self-cleaning windshields and more efficient batteries.

Water clings to most materials, either soaking in or beading up, depending on surface area and composition. The new material, etched from silicon, resembles a microscopic bed of grass. Each "blade" is a few nanometers thick--about 100,000 times smaller in diameter than a single human hair. When liquid drops onto the tiny blades, it suspends itself on their tips without sinking between. The blades "reduce the surface area the droplet feels," says Krupenkin, so the liquid beads up effortlessly. When the researchers charge the silicon with electricity, the energy field pulls the liquid down into the gaps, and the "nanograss" wets instantly.