Dr. Todd A. Kuiken pulls up a video clip on his computer. A department director at the Rehabilitation Institute of Chicago and an associate professor at Northwestern University's medical school, Kuiken is sitting in his 11th-floor office. On the screen, the mini-movie shows a man in a white T-shirt putting on a bright-yellow trucker's cap. "Yo," he says and bows after snuggling the cap on his head.
Big deal, huh? Well, yes, it is. The man, a former power-company worker named Jesse Sullivan, has no arms. His limbs were destroyed to the shoulder when he accidentally touched a high-voltage line in 2001, so he must now maneuver a computerized arm wired to nerve stumps in his chest and controlled, down to each fingertip, entirely by electrochemical impulses. In other words, by thought. Kuiken swivels at his desk, as if to take a bow himself. And a bow would be well-deserved: Sullivan's custom-made prosthesis -- the world's first brain-powered arm -- is Kuiken's brainchild.
Bionic humans have long been the stuff of science fiction. Kuiken, 45, remembers watching The Six Million Dollar Man on TV as a teenager before heading off to the University of Idaho in 1978 to study mechanical engineering. Even now, despite advances in robotics and neurology, most people who have had at-the-shoulder amputations use a mechanical device made of straps and cables that dates to the Civil War.
Kuiken set out to better meld man and machine 25 years ago while simultaneously pursuing his medical degree and a PhD in biomedical engineering at Northwestern University. His dual interests turned out to be critical, allowing him to succeed where a narrowly focused engineer or doctor would have come up short. Previously, researchers had shown that nerves could be hard-wired to electronic devices. But myoelectric impulses -- the stop-and-go signals of the body's muscle system -- are often too faint for computers to interpret accurately. Kuiken, a lifelong tinkerer who built treehouses and his own Soap Box Derby racer as a boy, found a way to amplify those charges, working with lab rats in the 1980s.
Although this research took years, it turned out to be a snap compared with what followed. Collaborating with Allen Taflove, a Northwestern professor of electrical and computer engineering, Kuiken had to decode the muscular signals to differentiate between one telling the forearm to move, for example, and another ordering the fingers to close. They attached 115 electrodes to nerves that had been rerouted in Sullivan's chest. Then they asked him to perform 26 different motions so they could learn the exact combination of impulses for each move. Kuiken also needed a semiconductor-packed arm that could follow these directions in real time. For that, he turned to Liberating Technologies Inc., a prosthetic-device maker in Holliston, Mass. Finally, in 2002, Kuiken was ready to test a bionic arm on a person -- and there was Sullivan, already in the Rehabilitation Institute after his double amputation.
Today, Sullivan can do many of the things he did before, though not as naturally: He dresses and feeds himself, shaves, uses scissors, vacuums, and works in the garden. He can even toss a ball. Unexpectedly, he can also feel: The re-innervated nerves in his pectoral muscles can receive signals, so he can sense whether an object he has picked up in his mechanical hand is hard or soft, hot or cold.
Kuiken imagines that one day people might become bionic beings like TV's Colonel Steve Austin. But he says that's probably decades away. "The reality is that this," he says, extending his right arm, "is the most incredible machine in the world. We cannot match this." What he's likely to do, though, is improve the lives of civilians and soldiers who lose their arms and legs by the thousands every year.
By Michael Arndt