DARPA’s new prosthetic hand could let amputees feel touch sensations

More than 1,600 US service members have undergone major limb amputations due to battle injuries in America's post-9/11 military operations. In the future, they and millions of amputees around the world could benefit from technology that would allow them to feel sensations through prosthetics wired to their brains.

The Defense Advanced Research Projects Agency (DARPA) announced this week that it's made a breakthrough in prosthetic technology that would allow just that. DARPA took a prosthetic hand designed by researchers at the Applied Physics Laboratory at Johns Hopkins University, wired it via electrodes to the motor and sensory cortices in the brain of a 28-year-old volunteer, and tested to see whether he had feeling in his artificial fingertips. He did.

The research came out of DARPA's Revolutionizing Prosthetics project — an interdisciplinary initiative founded in 2006 with the goal of creating a new generation of prosthetics that would give users near-natural dexterity and sensation.

DARPA has already made significant advances in prosthetic functionality. In 2014, the US Food and Drug Administration approved the sale of a DARPA-funded prosthetic arm, the DEKA Arm System, which allows users to control the prosthesis via signals sent from electrodes implanted in their muscles.

A recent version of the DEKA arm is called the "Luke," a reference to an icon of futuristic prosthetic technology, Luke Skywalker.

Users can control the DEKA arm to perform complex tasks, but it's missing something that would make performing those tasks significantly easier and more natural: sensory touch feedback.

This new research suggests that capability could be built into future prosthetics.

“We’ve completed the circuit,” Justin Sanchez, program manager of DARPA's Revolutionizing Prosthetics project, said in a statement. “Prosthetic limbs that can be controlled by thoughts are showing great promise, but without feedback from signals traveling back to the brain it can be difficult to achieve the level of control needed to perform precise movements. By wiring a sense of touch from a mechanical hand directly into the brain, this work shows the potential for seamless bio-technological restoration of near-natural function.”

To test the hand's performance, researchers blindfolded their volunteer and touched each of the prosthetic's fingertips. In addition to being able to control the hand with his thoughts, he was able to identify which finger had been touched with almost 100 percent accuracy. 

"The feeling, he reported," DARPA's statement claims, "was as if his own hand were being touched."

“At one point, instead of pressing one finger, the team decided to press two without telling him,” said Sanchez. “He responded in jest asking whether somebody was trying to play a trick on him. That is when we knew that the feelings he was perceiving through the robotic hand were near-natural.”

For now, that's as much as DARPA has said about the technology.

Here's hoping there will be a mindblowing video soon.