A new material covered with nanoscopic hairs that mimic those found on geckos’ feet could allow people to walk up to sheer surfaces and across ceilings, say researchers.
Andre Geim and colleagues at the UK’s Manchester University say covering a person’s hand with the material would be enough to let them stick to the ceiling. The tape could be detached from the surface by simply peeling it slowly away from one side.
“Spiderman is science fiction and will remain in comics,” Geim told New Scientist. “But hopefully ‘gecko-man’ will become less science fiction and more a reality in the near future.”Geckos can climb even the most slippery surface with ease and hang from glass using a single toe. The secret behind this extraordinary climbing skill lies with millions of tiny keratin hairs – called setae – on the surface of each foot. An intermolecular phenomenon known as van der Waals force is exerted by each of these hairs. Although the force is individually miniscule, the millions of hairs collectively produce a powerful adhesive effect.
Soft and flexible
Researchers at Carnegie Mellon University recently announced that they had made synthetic setae that exert a similar force. But Geim’s team has now gone further by demonstrating a material made of millions of such artificial hairs.
The researchers found that the synthetic hairs had to be soft and flexible enough to attach to uneven surfaces but not so weak that they would break easily or bunch together. The substrate that the hairs were mounted on also had to be sufficiently flexible for the material to work.
“Flexibility comes from the hairs themselves and the base material,” Geim says. “This flexibility can compensate for unevenness or dust on contacted surfaces.”
Each synthetic hair is made from a material called kapton and measures 2.0 microns in height and 0.2 microns in diameter – the same as gecko hairs. The hair-covered tape is made using a mould created by a lithographic process. A piece of tape one centimetre square holds around 100 million of these artificial setae and could support a weight of one kilogram.
The researchers believe the material could have many applications, from new types of vehicle tyre to robots that can climb up walls.
But Geim admits that the current fabrication method does not lend itself easily to mass production of the tape. And a more serious concern is how to make the artificial setae durable enough to be reapplied many times, he adds.