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Science seeks brawn as well as brains

Artificial muscles could one day lead to more sophisticated robot and prosthetic devices.

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(CNN) -- Since Deep Blue's victory over chess champion Gary Kasparov, humans have had to grow used to the idea of being eclipsed by computers in the most intellectual of mind games.

But technophobes can take satisfaction from the fact that we are still capable of administering a beating to machines when it comes to more muscular forms of competition.

When the first "Man vs. Machine" arm wrestling competition was held last year in California, the one human competitor -- in actual fact a 17-year-old girl -- easily defeated all three of her robotic rivals.

Of course, mechanical arm-wrestling machines are nothing new -- they have been a staple of seaside amusement arcades for years.

But what sets the new devices apart is that they are powered by plastic artificial muscles which scientists hope could one day lead to a new generation of more sophisticated and dextrous robotic and prosthetic devices.

The arm-wrestling contest, the brainchild of Dr. Yoseph Bar-Cohen of NASA's Jet Propulsion Laboratory in Pasadena, was established to promote research in the field.

"I said in 1999 that I wanted to see an arm wrestling contest between a robot and a human. At the time I thought it would take 20 years for that competition to happen because the materials were really bad in terms of force," Bar-Cohen told CNN.

Advances in the engineering of artificial muscles have been boosted by recent developments in electroactive polymers (EAPs), synthetic materials which can be made to change shape by applying an electrical charge.

While human muscles can only change length by around 20 percent, EAPs can stretch up to several times their original length at far quicker speeds.

But muscle tissue still enjoys huge advantages over its artificial imitators. Muscle fibers can self-repair naturally, enduring far longer than the lifespan of any mechanical device. By converting chemical energy into mechanical energy, they also enjoy a lightweight fuel efficiency without any need for bulky batteries or engines.

Bar-Cohen said that the successful imitation of muscular mechanics would eventually lead to a range of new technologies, such as human-like robots and better prosthetics.

"In principle it can affect everything we can think about," he said. "We can have all kinds of prosthetics, augmenting muscles inside and outside the body. In space exploration, I envisage some sort of robot that -- instead of having wheels -- could run, climb and fly. Imagine what that could do for future NASA missions."

One important breakthrough towards that goal could be the success of Dr. Ray Baughman of the NanoTech Institute, Texas, in building artificial muscles powered by alcohol and hydrogen, as reported in the journal Science earlier this year.

The muscles, made from carbon nanotubes which simultaneously act as both fuel cell and muscle, are 100 times stronger than natural muscle. But Baughman is experimenting with more flexible materials in an effort to improve the contracting ability of the muscles, currently only around one percent.

"The nice thing about carbon nanotubes is the multifunctionality," Baughman told CNN. "But if you want to get human-type strokes you have to go to a conducting material that has a lower stiffness."

Ultimately however, Baughman said he hoped fuel advances in artificial muscle engineering could lead to the development of an artificial heart powered by blood sugar, just like a natural heart.

Such breakthroughs remain a long way off. In the meantime, Baughman is also developing metal-based artificial muscles built from shape-memory wiring, which he believes could revolutionize prosthetic technology and also enable the development of strength-amplifying exoskeletons for use by soldiers and the physically impaired.

"The technology closest to commercialization is the one based on shape-memory materials," said Baughman. "It would be nice to have a situation where the minor movements of a person who is frail could be amplified via an exoskeleton to provide normal abilities."

Baughman's shape-memory, metal-based muscles are banned from Bar-Cohen's arm wrestling contest, with good reason. "If we entered that competition there is no way in the world the human could win," he said. "They're going to slam that hand down, that's not an issue."

In the meantime, human arm wrestlers can rest easy. They may lose eventually but it's going to be a while before a robot grapples them into submission, Bar-Cohen predicts.

"It took a while for the computer to win at chess but it happened," said Bar-Cohen. "The challenge is like any competition -- eventually somebody is going to win. Then we'll have to think of boxing or something but for now we don't have to worry."

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