The DEKA Gen-3 Arm System is a motorized arm with 10 degrees of motion.
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Thus, DARPA’s program has been developing along two research tracks, one of which involves the more pressing goal of developing a significantly improved prosthetic — a “strap-and-go arm” that doesn’t require surgery. DARPA has achieved success with the DEKA Gen-3 Arm System, developed in collaboration with Manchester, N.H.-based DEKA Integrated Solutions. Last year, the company­ submitted an application to federal officials to sell the prosthetic commercially.

Resnik has been working with the robotic DEKA arm as the principal investigator for two related Veterans Affairs (VA) studies. Nicknamed “Luke” after Luke Skywalker, it comes in several different models, depending upon how much of a patient’s arm has been amputated. The full arm can achieve 10 degrees of freedom; users can operate it through various modes. One common approach is by using foot controls, in which a motion-sensor device (roughly the size of a matchbox) is inserted into the laces or otherwise is attached to the shoe.

The technology, which is tailored to the user’s preferences, then sends information about movement and speed wirelessly to move the Gen-3 arm. For example, it might be programmed so when the user lifts his toes on one foot, the arm will bend. And, when he lifts his heel, the same arm will straighten.

One woman in the VA study was able to return to her sewing passion, stitching together an apron. “A lot of our subjects want to cook and are very happy to be able to have two arms to use in cooking tasks,” Resnik says.

Last year, VA researchers launched a home-based study to track how the DEKA arm functions outside of a research setting. If the arm is commercially approved, Veterans Affairs and Department of Defense officials “are ready to go and acquire these for the veterans who qualify for them,” Ling says. As of this spring, no purchasing decision had been made — but roughly 300 veterans have expressed a strong interest in becoming the first users.

THE MOON SHOT, THOUGH — and the second research avenue that involves Scheuermann — focuses on integrating an artificial arm with the body’s own neuro-circuitry. “Clearly, we had to tie this directly into the brain so that the patient could just think about it and make it work,” Ling says. Led by Johns Hopkins University’s Applied Physics Laboratory (APL), the idea is to enable more natural prosthetic movement by accessing the brain’s own nerve pathways. The concept, which Ling describes as “pretty Space Age–thinking,” is not as farfetched as it might initially sound. When you close your eyes and move your arm up and down, you still sense where it’s located, says Bob Armiger, a biomedical engineer at the Johns Hopkins lab. “When you lose an arm, you don’t lose that sense of the limb itself,” he says, explaining that the related brain region likely remains intact.