For those with prosthetic arms, the ability to grab or hold things is empowering, but the inability to feel them – to determine whether something is hot or cold, hard or soft – can be frustrating. Now, a breakthrough from the team at Case Western Reserve University gives amputees with prosthetic limbs the ability to “feel” something that they touch or hold.
As Igor Spetic, a 49-year-old amputee who lost his right hand in a work-related accident five years ago, explains, it is not exactly the same, but it is a lot better than previous technology. Spetic is now able, with the use of a prosthetic, to understand what things are just by touching them. This makes it easier to manipulate delicate items and more precisely hold them, enabling him to cut fruit, hold a coffee cup, or open bags with both hands, rather than with one hand and his teeth.
The prosthetic hand was created by researchers at Case Western with the help of a $4.4 million grant from Defense Advanced Research Projects Agency (DARPA). Spetic can’t actually feel a cotton ball, for example, touched to his new hand, but the electric signals sent to his brain by a computer let him interpret exactly what the cotton ball is. When blindfolded, Spetic knew the cotton ball was cotton and he said the hairs on his arm rose when the cotton ball was dragged across the prosthetic.
“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.”
While prosthetic research is getting increasingly advanced, the Case Western researchers have been able to find a way to connect sensors in the hand to receptors in the brain and enable the user to understand just what the sensors are sensing. The sensors measure the “pressure applied to various objects,” according to Time Magazine, and then convert the measurements into neural (brain) code. This code is then sent through wires implanted in Spetic’s arm around nerve bundles and then the signals are sent to his brain using neural pathways that weren’t damaged by the amputation.
Dustin Tyler, leader of the project, hopes to have a fully implantable system available for the public within the next five years. “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,” Tyler said.
Images via Case Western Reserve University