Scientists invent spectacular Spider-Feet

Reuters

HERE COMES: Scientists at the University of Melbourne have come up with a device that could soon allow humans to walk on walls like Spider-Man.

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When Spider-Man began scaling buildings, his "web-shooters" were considered nothing more than a fantasy, the creation of an imaginative comic book writer.

Not any more.

Scientists have come up with a device that could soon allow humans to walk on walls.

The palm-size contraption, made of layers of metal and silicon wafers, is no thicker than a credit card.

To make the device sticky, a film of water, held in the bottom layer, is pushed through tiny holes in the middle layers to the surface by an electric pump.

The droplets on the surface then acts as a bridge that sticks the device to another surface.

Sally Gras, of the University of Melbourne, said the adhesion comes from strong forces interacting between the water droplets and the other surface.

The most exciting thing about the device was that the stickiness could be switched on and off, she said.

Previous developments on self-adhesive devices had often been based on a vacuum, which stuck more permanently to a surface, Dr Gras said.

''This device pumps out droplets of water [to the surface] and then sucks them back in,'' she said.

''When it sucks them back, it no longer has the force [to stick] because the water has gone.

''It can be switched on and off in less than a millisecond.''

All it needs to run is a battery, and it can adhere to many surfaces including plywood, sandpaper, lino, brick and tiles.

The lead author behind the research, Paul Steen, of Cornell University in the United States, said the device could be used to make Spider-Man-style gloves or shoes.

A more practical application could be for super-sticky Post-it notes that could support considerable weight or be reused.

The device was inspired by a beetle native to Florida that can stick to a leaf with a force 100 times its own weight, said Professor Steen, whose research has been published in Proceedings of the National Academy of Sciences.

A limitation of the device, Dr Gras said, was that it could only hold 10 grams - the weight of about 70 paper clips.

But she said this problem could be overcome.

The smaller and more numerous the holes in the surface layer, the stronger the adhesive force could be, the authors wrote.

They estimate the same device, with a million holes, could hold about seven kilograms - about the weight of a small cat.

''It's very exciting in the short term and very promising in the long term,'' Dr Gras said.

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