A high-tech prosthetic hand allows users to experience touch. Credit: University of Utah.

An electrical accident 17 years ago claimed Keven Walgamott’s hand. Now, researchers at the University of Utah have fitted the man with an innovative prosthetic arm whose fingers not only move with his thoughts but are also capable of relaying sensations. Essentially, this is a prosthetic hand that feels. It’s so sensitive that Walgamott was able to hold an egg between his fingers without breaking it by squeezing it too hard.

The prosthetic hand that feels

The technology was developed by a team led by biomedical engineering associate professor Gregory Clark. The backbone of the prototype is the Utah Slanted Electrode Array (USEA), which is an interface between the prosthetic hand and the patient’s remaining sensory and motor nerves in the arms.

USEA consists of hundreds of electrodes that are surgically implanted next to the nerve fibers. The electrodes pick up the ‘chatter’ of nearby nerve fibers, forming a connection between the prosthesis and the nervous system.

The prosthetic — called “LUKE” after the prosthetic Luke Skywalker wore in Star Wars — was fitted to Walgamott in 2017. Since then, he has been training closely with the researchers at the University of Utah to perform extremely delicate tasks that would have been otherwise impossible using metal hooks or claws prosthetics.

“It almost put me to tears,” Walgamott said. “It was really amazing. I never thought I would be able to feel in that hand again.”

Scientists have been working on the LUKE arm for more than 15 years. It’s mostly made of metal motors and parts which control finely articulated fingers, along with an external battery that’s wired to a computer. Sensors cover the hand that sends signals to the nerves via the microelectrode array, mimicking the feeling you feel in your hand when picking up something.

Star Wars-inpired

One huge breakthrough in developing LUKE’s touch involved understanding and recreating how the brain interprets first touching something.

“Just providing sensation is a big deal, but the way you send that information is also critically important, and if you make it more biologically realistic, the brain will understand it better and the performance of this sensation will also be better,” said Clark.

Although the quality of touch that Walgamott can feel with his new prosthesis isn’t nearly as sensitive as a real hand, this is still a huge leap from nothing at all. With it, Walgamott can distinguish between touching something soft or hard, the kind of sensitivity that allows him to live a fuller life. For instance, the researchers claim that the man is now able to perform complex movements such as picking grapes or stuffing a pillow into its case.

For Walgamott, these training sessions have been incredibly emotional.

“One of the first things he wanted to do was put on his wedding ring. That’s hard to do with one hand,” says Clark. “It was very moving.”

Next, Clark and colleagues plan to improve the design of the prosthetic to make a mobile version. Right now, it can only be used in the lab where it has to be hooked up with all sorts of bulky machinery.

Clark hopes that in 2020 or 2021, three participants will be able to take their arms home, as long as they receive FDA approval.

It’ll take years, though, before such devices are commercially available. Nevertheless, it’s incredibly inspiring to see technology truly in service of the people.