ENGINEERS frequently admire the ways in which living creatures solve problems. However, they rarely manage to emulate them. But Andrey Geim, from Manchester University, in England, and his colleagues have done so. In a paper just published in Nature Materials, they describe how they replicated the way that geckos cling to ceilings in a new, glue-free adhesive tape.
A gecko's powers come from tiny hairs on the soles of its feet. Each hair sticks to any surface it touches by a combination of capillary action due to water it has absorbed and so-called van der Waal forces—electrostatic interactions between individual molecules. Though the attraction between a hair and a surface is tiny, geckos have zillions of such hairs, and the sum of the interactions is enough to hold a lizard to the ceiling.
Dr Geim and his colleagues used electron-beam lithography (a technique employed in the manufacture of computer chips) to fabricate small pieces of plastic tape that had hairlike protuberances on their surfaces. They created a range of surfaces with hairs measuring between a fifth of a micron (millionth of a metre) and four microns in diameter, and with around 100m hairs per square centimetre. Dr Geim reckons that a person wearing gloves made from the tape could stick to a wall as well as a gecko does. He has not yet done that experiment, though, for the pieces of tape that the team has produced so far are only a square centimetre in area.
There is still some way to go before gecko tape becomes a commercial reality. The prototype is delicate stuff, losing its adhesive powers after three or four uses. And electron-beam lithography does not lend itself to mass production. But if it could be made cheaply, geckotape would have many uses. Move over Spiderman: Geckoman is on his way.