The average person takes being able to pick up delicate objects without destroying them for granted. But not Keven Walgamott who lost the use of his left hand and part of his arm 17 years ago after suffering an electrical accident and agreed to help test an exciting new kind of artificial limb that lets the wearer feel sensations.
A team of University of Utah biomedical engineers, headed by associate professor Gregory Clark, got feedback from seven test subjects on the prototype model of their invention, an advanced prosthetic arm with fingers that responds to thought and provides the sense of feeling to disabled body parts.
Walgamott, who now sells real estate in West Valley City, Utah, said he could “feel” an egg he picked up. Furthermore, the surprised product tester found he could control the prosthetic hand with his thoughts to prevent applying too much pressure that would crush the fragile shell.
This is a huge scientific breakthrough that could improve the lives of countless people who need physical help through replacement of artificial limbs.
Clark’s research and development team named their brainchild “the LUKE arm” after the fictional character and science fiction hero Luke Skywalker who was outfitted with a bionic hand in the movie “The Empire Strikes Back.” The LUKE arm imitates how a human hand normally feels objects by transmitting the corresponding signals to the brain.
Fifteen years in the making, the LUKE Arm consists mainly of metallic motors and other parts. Transparent silicone “skin” covers the hand. An external battery powers the prosthetic limb and connects through cabling to a controlling computer.
The mechanics for the ground-breaking prosthetic came from DEKA Research & Development Corporation in New Hampshire, founded by none other than the man who introduced the Segway, Dean Kamen.
But it was the University of Utah team that came up with a way to connect the bionic arm to the amputee’s central nervous system – thanks to a previous invention called the Utah Slanted Electrode Array, credited to Emeritus Distinguished Professor of Biomedical Engineering Richard A. Normann.
The Array bundles 100 microelectrodes and wires that are inserted surgically into the recipient’s forearm nerves and wired to an external computer outside the body. The novel electronic system interprets the signals from still-functioning arm nerves and relays them to the computer which converts them to digital signals that instruct the arm to move.
But visual observation and mere movement aren’t enough to know how much pressure to apply to an object to keep it from breaking or slip through the fingers.
Team member Jacob George, a biomedical engineering doctoral student, commented on the group’s study which was featured in the July 24, 2019 issue of Science Robotics:
“We changed the way we are sending that information to the brain so that it matches the human body. And by matching the human body, we were able to see improved benefits. We’re making more biologically realistic signals.”
A standard prosthetic comes equipped with metal hooks or claws for hands which provide no sensory feedback to the amputee and make performing delicate tasks – such as threading a needle – difficult to impossible.
Walgamott was so happy with the results of his first clinical trial in 2017 that he almost cried:
“It almost put me to tears. It was really amazing. I never thought I would be able to feel in that hand again.”
Not only could Walgamott pick up an egg without breaking it, he plucked grapes without crushing them. Best of all, when he held his wife’s hand, he experienced a feeling in the prosthetic’s fingers that were very much like what he remembered before his injury.
Lead researcher Clark confirmed how important the sense of touch was to Walgamott:
“One of the first things he wanted to do was put on his wedding ring. That’s hard to do with one hand. It was very moving.”
As described in the Science Robotics abstract, the interdisciplinary group’s DEKA LUKE arm is a “bidirectional neuromyoelectric prosthetic hand that conveys biomimetic sensory feedback.” The landmark technology evokes “tactile percepts on the phantom hand.”
After sensory feedback was enabled via the computer, “the participant exhibited greater precision in grip force and was better able to handle fragile objects.”
By actively manipulating objects, test subjects could tell whether they were small and large, as well as gauge softness or hardness.
Under development now is a wireless, completely portable version of the DEKA LUKE Arm, which, along with the sense of touch, will also be able to provide sensory feedback to the wearer about pain and temperature.
First trials involved people whose arms had been removed below the elbow – where the muscles that move the hand are located – but Clark’s team is expanding their work to include amputees who lost their extremities above the elbow.
If the U. of Utah team gets the nod from federal regulators, Clark said that at-home use by three volunteer testers is slated for 2020 or 2021.