Test of might pits man vs. machine

You don't often find scientists staging arm-wrestling tournaments — let alone competing in them. But the match scheduled tomorrow at the International Society for Optical Engineering conference in San Diego is no ordinary bout.

For the first time, researchers plan to pit man-made muscle against living tissue — in this case the sinewy limb of a San Diego high-school senior. The purpose: to spur scientific interest in a little-known but promising class of plastics that expand and contract when jolted by an electrical charge.

Officially known as electroactive polymers, the material more frequently is referred to by its nickname: artificial muscle.

Long regarded as a laboratory curiosity, the material has begun attracting more-serious attention. Researchers are incorporating it in plans for everything from toys and robots to implants and prosthetics. Some scientists envision a day when the material might replace real muscle in people whose own fibers have failed.

"The properties of artificial muscle are getting much closer to that of biological muscle," said Selahattin Ozcelik, a Texas A&M University robotics researcher.

Theoretically, Ozcelik said, artificial muscle can be used in place of any mechanical motor and offers several key advantages. Lighter than a traditional motor, artificial muscle can unleash quick bursts of stored energy. As a plastic, it's also capable of bending and twisting.

Financed by a small grant from the Office of Naval Research, Ozcelik and his colleagues have designed a snakelike robot composed entirely of braided artificial muscle fibers.

By electrically stimulating the fibers in the right sequence, Ozcelik said, the robot could slither into tight spaces or over rough terrain in ways that a mechanical robot would find hard to match.

For this reason, the National Aeronautics and Space Administration and the Defense Department fund several projects to meld robotics and artificial muscles.

Other scientists are considering medical applications.

At the University of California, Irvine, biomedical engineer William Tang and one of his students have launched a project to develop a prosthetic hand with artificial muscles. Unlike mechanized models now in use, a plastic-powered prosthetic could be more deft and ultimately stronger, Tang said.

"We could also potentially make the motion more lifelike," he added.

Implants also are in the works. Mohsen Shahinpoor, director of the Artificial Muscle Research Institute at the University of New Mexico, has designed an eye implant to correct bad vision.

The fix, he said, involves wrapping a small band of artificial muscle around the eyeball. Stitched to the sclera, the eye's protective white outer layer, the material would tighten or slacken in response to a hearing aid-like electromagnet behind the ear.

As the band squeezes and relaxes, it changes the shape of the eyeball, which determines whether images appear fuzzy or crisp.

Shahinpoor, who has launched a small company called Ophthalmotronics, said the idea has been tested only in animals and cadavers, but he hopes to receive approval for further tests.

Artificial-muscle technology also may be a boon for toymakers. A small Japanese company called Eamex has introduced the first artificial fish tank. The colorful, eerily lifelike fish contain no mechanical parts or batteries. Instead, artificial muscles in their tails swish in response to an electric signal beamed by a hidden antenna.

Scientists stress that considerable technical hurdles remain. Among them: boosting the strength of artificial muscles while simultaneously reducing the electrical power they require.

That's where the arm-wrestling comes in.

Three teams have entered the competition: one from the Swiss Federal Institute of Technology, another from the University of New Mexico, and a team of undergraduate underdogs from Virginia Tech.

Representing humanity in this man-vs.-machine matchup is 17-year-old Panna Felsen. "I'm not very strong," she said, "so chances are they're going to beat me."