By mimicking the biology of a lizard, scientists have invented a material that could one day enable people to walk up walls or hang from ceilings, just like Spider-Man.
The substance, described in the journal Nature Materials, consists of a tape covered with a dense array of microscopic hairs -- much like the hairs covering the soles of a gecko's feet.
The climbing ability of geckos has long intrigued scientists, who for years assumed that the hairs on the animals' feet must be covered with some kind of glue. Last year, they learned that weak tugs between molecules, known as Van der Waals' forces, cause the animals' feet to stick on their own.
Andre Geim of the University of Manchester in England and co-workers set out to create an artificial surface studded with gecko-like hairs using micro-fabrication technologies.
Success came after the scientists cooked up hairs that were flexible enough to stick to uneven surfaces yet strong and thick enough not to collapse or break easily. The hairs were then stuck onto a soft, flexible tape.
Geim and colleagues demonstrated the power of their material by sticking some of it onto the hand of a Spider-Man toy and showing that the toy could hang upside down from a plate of glass.
There are still many technical issues to be resolved, the authors said. Their gecko tape is extremely expensive to make. It also fails after a number of detachments and reattachments -- the last thing any would-be Spider-Man would want.