Researchers Build Rocket-Powered Arm

Almost in time for the new Bionic Woman series, a group at Vanderbilt University is promising that its prosthetic arm, which uses a miniature rocket motor, could be the next revolution in prosthetic devices. Okay, so it doesn’t give the wearer superhuman strength, but researchers involved in this DARPA-funded effort claim that it does come close to the strength of a real arm, which is why its powered by a rocket motor, rather than by a battery:

The prototype can lift (curl) about 20 to 25 pounds – three to four times more than current commercial arms – and can do so three to four times faster. "That means it has about 10 times as much power as other arms despite the fact that the design hasn’t been optimized yet for strength or power," [Michael Goldfarb, the professor of mechanical engineering who is leading the effort] says.

The mechanical arm also functions more naturally than previous models. Conventional prosthetic arms have only two joints, the elbow and claw. By comparison, the prototype’s wrist twists and bends and its fingers and thumb open and close independently.

Of course, there were two prosthetic arms displayed at DARPATech earlier this month; and Vanderbilt was not among them. Apparently, the Vanderbilt team is saying that its arm — because it takes the riskiest approach — will take longer to develop. "DARPA set a goal of developing a commercially available arm in two years. Because of our novel power source, the process of proving that our design is safe and getting regulatory approval for its use will probably take longer than that," Goldfarb says.

The issue for Vanderbilt — and perhaps DARPA — is when this army will be ready:

The Vanderbilt arm is the most unconventional of three prosthetic arms under development by the Defense Advanced Research Project Agency (DARPA) program. The other two are being designed by researchers at the Advanced Physics Laboratory at Johns Hopkins University in Baltimore who head the program [ed. It’s the Applied Physics Laboratory, which is in Laurel, Maryland]. Those arms are powered by batteries and electric motors. At the same time, the program is supporting teams of neuroscientists at the University of Utah, California Institute of Technology and the Rehabilitation Institute of Chicago who are developing advanced methods for controlling the arms by connecting them to nerves in the users’ bodies or brains.

"Battery power has been adequate for the current generation of prosthetic arms because their functionality is so limited that people don’t use them much," Goldfarb says. "The more functional the prosthesis, the more the person will use it and the more energy it will consume."

Researchers at the university are apparently worried that since their arm may not be picked up for further funding by DARPA, but are hoping if that happens, they will get alternative funding.