Secret to 'Spidey Suit' Revealed

Sept. 17, 2007 — Peter Parker wannabes: listen up. A scientist has come up with a Spiderman suit design that could have you fighting crime and rescuing damsels in no time.

The design proposes using the self-cleaning, adhesive power of engineered molecules known as carbon nanotubes to produce gloves and boots that would allow a person to cling to walls and sling invisible cable that would afford skyscraper-swinging.

And although the scheme may not supplant Spidey's superhero skills, it could form the theoretical basis for wall-clinging suits that could be used on Earth and in space.

"It's the possibility of a Spiderman suit," said Nicola Pugno, professor of structural mechanics at the Polytechnic University of Turin in Italy, who published the research in the Institute of Physics' Journal of Physics: Condensed Matter .

"You need formulas to give you guidelines in order to suggest how you have to perform the experiments."


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Pugno's inspiration for the suit comes not so much from spiders but from geckos, lizards renowned for their ability to grip any surface and the way they can hang from a ceiling even by one toe.

The secret to the gecko's scaling talent lies in the structure of millions of microscopic elastic hairs on their toes. Called setae, the hairs branch off into even smaller fibers called spatulas.

The fibers are so miniscule that molecules inside come into close contact with molecules located within the surfaces the lizard is walking on. The molecular forces attract each other, giving the gecko just the right amount of staying power, but not too much that it can't lift up its foot and set it back down again.

Scientists have tried to mimic these forces using carbon nanotubes, but haven't yet found a way to mimic the structures big enough for human use. The problem is, the bigger they get, the more the molecules either stick to each other or lose the important molecular contact with the wall.

Pugno has proposed using the hierarchical structure of smaller and smaller fibers in the gecko's toe pad. It turns out that dividing a carbon nanotube fiber into smaller sub fibers increases the overall adhesive force. So gloves or boots coated with these materials would theoretically support the weight of a man.

He also suggests anchoring millions of carbon nanotube fibers in a plate that would keep the fibers 5 micrometers apart so that they do not become tangled. Each fiber would branch into smaller structures, allowing it to stick to different kinds of surfaces.

As for slinging web-like fiber, scientists have succeeded in making a 'cable' of four million nanotube fibers that resembles spider's silk. The 'silk' is invisible to the naked eye since it's thinner than the wavelength of light. But the mechanics of constructing such cable is something Pugno has not fully worked out yet.

"It sounds good, but is it fiction or is it real?" asked Ali Dhinojwala, a professor of polymer science at the University of Akron, Ohio.

To date, said Dhinojwala, no one has found a practical way to develop carbon nanotubes in hierarchical structure.

What's more, he said, just because something works for a gecko doesn't mean it would work for a human.

"Something working small and taking it to the weight of a human is an extrapolation," said Dhinojwala. Carbon nanotube fibers or hairs might be able to support the weight of a 200-pound man, but will his own arms?

"It's not the hairs that will break, it's the limbs," said Dhinojwala.

Related Links:

Polytechnic University of Turin in Italy

Institute of Physics' Journal of Physics: Condensed Matter

Wikipedia: The Gecko