Keven Walgamott wasn’t sure what to expect when scientists first hooked up what was left of his arm to a computer.
Last year – 14 years after he lost his hand and part of his arm in an electrical accident – he heard about a team at the University of Utah working on an experimental robotic arm. The prosthetic hand and fingers would be controlled by an amputee’s own nerves. Even more challenging, researchers were trying to restore the sense of touch to amputees through that robotic hand.
Walgamott volunteered for the experimental program. A few weeks after surgeons implanted electrodes into the nerves of his arm last year, he found himself hooked up to a computer getting ready to touch something with his left hand for the first time in more than a decade.
The Utah researchers had created a computer program to simulate the feel of touching a virtual wall – an early test to prepare Walgamott for the robotic arm.
As Walgamott moved his arm, a virtual hand on the computer screen before him moved as well, plunking down the ridges of the corrugated wall.
“It was stunning. I could actually feel the wall. I could feel the bumps along it,” he said. “It almost brought tears to my eyes.”
Then researchers attached the robotic arm itself, putting Walgamott through a battery of tests over 14 months that had him touch and manipulate objects with it.
“When I went to grab something, I could feel myself grabbing it. When I thought about moving this or that finger, it would move almost right away,” he said. “I don’t know how to describe it except that it was like I had a hand again.”
At the Society for Neuroscience conference in Washington on Tuesday, the University of Utah team presented part of their work on adding the sense of touch and movement to prostheses – the latest step in the rapidly developing field of neuroprosthetics.
Over the course of the past year, while working with Walgamott as their key subject, they have found adding touch to prostheses markedly improves motor skills of amputees compared with robotic prostheses on the market. Adding the sense of touch to prosthetic hands also appears to reduce a painful feeling many amputees experience called phantom pain, and it creates a sense of ownership over the device, researchers said.
“By adding sensory feedback, it becomes a closed-loop system that mimics biology,” said Jacob George, a bioengineering PhD student at the University of Utah and lead author of Tuesday’s study. The goal, he explained, is to get prosthetic technology to a point where someone using a prosthesis wouldn’t have to think through every movement to pick up a cup. They wouldn’t even have to look at the cup. They would simply move the hand toward it using their brain and existing nervous system, feel it and pick it up.
The most cutting-edge prosthetic hands available can make sophisticated movements, but they require complicated – and often imprecise – methods of operation. Some rely on tilt motions by the user’s foot and others on movements by the muscles remaining in a user’s arm.
The Utah research group’s approach, however, relies on a device called the Utah Slanted Electrode Array. The device is implanted directly into the nerves in a subject’s arm. The USEA, along with electrodes implanted in muscles, allows amputees to control a robotic hand as if they were flexing or moving their original hand. The approach also allows signals like sensation to be transmitted back to the subject’s nervous system, creating a “looped system” – like in a human limb – where the hand’s feeling and movements inform each other.
“We often think of touch as one thing, but it’s more than that. It’s pressure, vibration, temperature, pain,” said Gregory Clark, the bioengineering professor leading the Utah research team. Because of that, it has required painstakingly slow work from a multidisciplinary team of experts – over the course of years – to build those sensations into the robotic arm, figure out which spot on the hand corresponds with which nerve fiber in the arm and the algorithms required to send touch signals back into the nervous system.
Clark’s team is part of a larger effort funded by the U.S. military’s Defense Advanced Research Projects Agency. DARPA launched its neuroprosthetic program in 2014 – called HAPTIX – with the goal of developing an advanced robotic arm within years that would help amputees feel and move intuitively. The researchers received additional funding from National Science Foundation.
The robotic arm the Utah researchers have been working with was developed under the HAPTIX program by the company DEKA (the company founded by Segway inventor Dean Kamen). The state-of-the-art robotic limb was dubbed the “Luke” arm by its makers, after the advanced prosthesis wielded by Luke Skywalker in “Star Wars.”
The results of the Utah group’s experimental tests so far have been both gratifying and inspiring, the researchers said.
Walgamott – a real estate agent in Utah – described the joy of being able to do everyday mundane tasks again with his left hand – like picking up an egg without crushing it, clasping his hands together and holding his wife’s hand.
But the highlight of his entire 14 months in the experimental program, he said, was being able to put a pillow into a pillowcase on his own.
“When you have just one hand, you learn to adapt,” he said, describing the infuriatingly slow process he usually uses for pillowcases, pulling them on inch by inch on each side, rotating the whole time. “To just take a pillow in one hand and put the pillowcase on with the other. I know it sounds simple, but it’s amazing.”
