Nanotube carpet mimics gecko feet
The talented gecko can walk up a glass wall or hang from the ceiling by only one toe. The little lizard owes its gravity-defying powers to carpets of microscopic hairs, called setae, covering its feet. These hairs, when in close contact with a surface, induce intermolecular attractive forces called van der Waals forces between themselves and the surface (SN: 7/15/00, p. 47: Available to subscribers at Gecko toes tap intermolecular bonds).
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Materials scientists have now created synthetic gecko foot hairs that stick to surfaces 200 times as strongly as the setae do. To make this superstrong adhesive, Ali Dhinojwala of the University of Akron in Ohio and his colleagues grew a forest of carbon nanotubes on glass. Next, they poured a liquid chemical onto the glass. The chemical solidified into a polymer matrix around the base of the tubes. The team then peeled the resulting polymer-nanotube “rug” off the glass.