For all the functionality and freedom that modern prosthetics provide, they still cannot give their users a sense of what they're touching. That may soon change thanks to an innovative electrode capable of connecting a prosthetic arm's robotic sense of touch to the human nervous system that it's attached to. The device is part of a three year, $1.9 billion DARPA project and is being developed by Daniel Moran and his team at Washington University in St. Louis. The electrode, technically called a macro-sieve peripheral nerve interface, is comprised of a thin contact lens-like material less than 20 percent the diameter of a dime. It reportedly allows its users to feel heat, cold and pressure by stimulating the ulnar and median nerves of the upper arm.
However, Moran's team must first determine how much sensory information is actually encoded in natural systems before they can begin incorporating them into people. They'll do so by implanting prototypes into the forearms of "nonhuman primates" and monitoring the stimulation of peripheral nerves using a technique known as current steering. "We want to see what they can perceive," Moran said in a statement. "If we stimulate this sector of the nerve, that tells them to reach to one side in a standard reaching task. We want to figure out how small we can make the stimulation so they can still sense it." With that data in hand, the team expect they'll be able to develop more accurate sensor suites in future prosthetics, like the Luke Hand that DARPA is already building.