Echoes of geckos.

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. 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.