A Prosthetic Hand That Can Feel

Igor Spetic, 49, lost his right hand in a work related accident five years ago. But on Oct. 9, he got to bring home an innovative prosthetic hand for the first time, one that not only has more precise gripping, but gives him back his sense of touch.

The hand was created by researchers at Case Western Reserve University, which was granted $4.4 million from the Defense Advanced Research Projects Agency (DARPA) for their work creating a prosthetic hand that can feel. The goal is to make a hand that allows someone to function in a way that allows him to forget he doesn’t’t have the real version.

“The user feels like an actual hand is touching the object. It feels real,” says Dustin Tyler, leader of the project and an associate professor of biomedical engineering at Case Western.

Until recently, Spetic had been testing Case Western’s technology in the lab, but in October he took the prosthetic home, and became one of the first people to test such advanced prosthetics in real world situations, outside of the artificial conditions in a lab. Already, he’s been able to accomplish small tasks that were once extremely difficult, like cutting fruits and vegetables with a knife, securely holding his coffee cup, and opening bags with both hands instead of using a combination of his teeth and left hand.

“What I’m excited about is knowing that I can go back from being one-handed to being a two-handed person,” says Spetic. “Of course it’s going to be a relearning of using a right hand that I haven’t had for 5 years, but I can hopefully be a two-handed person again.”

Prosthetics today are getting increasingly innovative, from prosthetic feet that allow ballroom dancers to dance again, to hands that move and grip naturally. What’s exciting about Case Western’s technology is that it creates a connection between the prosthetic and the brain, allowing users to actually feel the sensation of picking up on object.

Sensors in the prosthetic hand measure the pressure applied to various objects as the hand closes around them. The measurements are then recorded, converted into a neural code, and sent through wires to electrodes that were surgically implanted around nerve bundles in Spetic’s forearm and upper arm. When the neural code reaches Spetic’s nerves, the signal is transmitted through his healthy neural pathways that weren’t affected by his amputation, to his brain. The brain interprets the signals as feeling, as if from a normal hand.

“When [patients] see the prosthesis touching an object and feel their hand touching the object, they begin to think of the prosthesis as part of their body, again. It is no longer a foreign tool,” says Tyler.

With funding from the Department of Veteran’s Affairs Rehabilitation and Research Development, and DARPA, Tyler and his team are currently developing a fully implantable system that will communicate with the sensors in the hand through a wireless link. “Our goal is to have it ready within the next five years,” says Tyler. “That system will require approval from the FDA for use in clinical trials.”

For Spetic, the ultimate prosthetic is one that will react exactly like his left hand. But for now, he says the prosthetic—which is still being fine tuned—has given him back something he lost.

“The hope I have is that anybody that’s an amputee will be able to benefit from this system,” he says.