The Revolution Will Be Prosthetized

It’s October  at Duke University, in Durham, N.C., and Jonathan Kuniholm is playing “air guitar hero,” a variation on Guitar Hero, the Nintendo Wii game that lets you try to keep up with real musicians using a vaguely guitarlike controller. But the engineer is playing without a guitar. More to the point, he’s playing without his right hand, having lost it in Iraq in 2005. Instead he works the controller by contracting the muscles in his forearm, creating electrical impulses that electrodes then feed into the game. After about an hour he beats the high score set by Robert Armiger, a two‑armed Johns Hopkins University engineer who modified Guitar Hero to train amputees to use their new prostheses.

Armiger’s research is part of a nationwide effort to create a neurally controlled prosthetic arm. That arm has been the focus of much media attention, but that focus obscures the truly groundbreaking research typical of the Revolutionizing Prosthetics 2009 (RP2009) program.

The U.S. Defense Advanced Research Projects Agency (DARPA) is pouring at least US $71.2 million into the program in the hope that it will let amputees do what most people take for granted: make gestures, test the water in a teacup, turn a key, even peel the shell off an egg. Words like bionic and thought-controlled have been thrown at the project, but they don’t do justice to the sheer ordinariness of its purpose. DARPA isn’t looking for a superstrong “Six Million Dollar Man” arm; it just wants an arm that moves exactly like a real one does.

Yet even making just a garden-variety arm requires a herculean effort, not only in the field of mechatronics but in neuroscience, electrical engineering, cognitive science, signal processing, battery design, nanotechnology, and even behavioral science. This four-year project is wildly ambitious even by the standards of the Pentagon’s mad-science wing. After the program concludes at the end of 2009, many of the arm’s various technologies will go into FDA clinical trials and then out into the world.

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