Another demonstration of the power of biomimetics comes from the gecko. This lizards ability to walk up walls and along ceilings is of much interest, and not only to fans of Spider-Man. Two groups of researchers, one led by Andre Geim at Manchester University and the other by Ron Fearing at the University of California, Berkeley, have independently developed ways to copy the geckos ability to cling to walls. The secret of the geckos success lies in the tiny hair-like structures, called setae, that cover its feet. Instead of secreting a sticky substance, as you might expect, they owe their adhesive properties to incredibly weak intermolecular attractive forces. These van der Waals forces, as they are known, which exist between any two adjacent objects, arise between the setae and the wall to which the gecko is clinging. Normally such forces are negligible, but the setae, with their spatula-like tips, maximise the surface area in contact with the wall. The weak forces, multiplied across thousands of setae, are then sufficient to hold the lizards weight.
Both the British and American teams have shown that the intricate design of these microscopic setae can be reproduced using synthetic materials. Dr Geim calls the result gecko tape. The technology is still some years away from commercialisation, says Thomas Kenny of Stanford University, who is a member of Dr Fearings group. But when it does reach the market, rather than being used to make wall-crawling gloves, it will probably be used as an alternative to Velcro, or in sticking plasters. Indeed, says Dr Kenny, it could be particularly useful in medical applications where chemical adhesives cannot be used.
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