A biomedical engineering team at the University of Utah has helped to develop a prototype of a high-tech prosthetic arm with fingers that can move and feel via the user’s thoughts.
The team, led by University of Utah’s biomedical engineering associate professor Gregory Clark, PhD, has developed a way for the LUKE prosthetic arm (named after the arm that Luke Skywalker got in the Empire Strikes Back) to mimic the way a human hand senses objects by sending the appropriate signals to the brain. Their findings were published in the Journal 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,” Clark said. “We’re making more biologically realistic signals. That means an individual wearing the prosthesis can sense the touch of something soft or hard, understand better how to pick it up, and perform delicate tasks that would otherwise be impossible with a standard prosthetic device, “ Clark said.
Kevin Walgamott, one of seven test subjects at the university, was able to pluck grapes without crushing them, pick up an egg without cracking it, and hold his wife’s hand with a sensation in the fingers similar to that of an able-bodied person.
“One of the first things he wanted to do was put on his wedding ring. That’s hard to do with one hand,” Clark said.
“It almost put me to tears,” Walgamott says about using the LUKE Arm for the first time during clinical tests in 2017. “It was really amazing. I never thought I would be able to feel in that hand again.”
The LUKE arm has been in development for nearly 15 years and is made of mostly metal motors and parts with a clear silicon skin over the hand. It is powered by an external battery and wired to a computer. It was developed by DEKA Research and Development.
Meanwhile, the U’s team has been developing a system that allows the prosthetic arm to tap into the wearer’s nerves, which are like biological wires that send signals to the arm to move. It does that thanks to an invention by U biomedical engineering’s Professor Richard A. Normann called the Utah Slanted Electrode Array. The array is a bundle of 100 micro-electrodes and wires that are implanted into the amputee’s nerves in the forearm and connected to a computer outside the body. The array interprets the signals from the still-remaining arm nerves, and the computer translates them to digital signals that tell the arm to move.
But it also works the other way. To perform tasks such as picking up objects requires more than just the brain telling the hand to move. The prosthetic hand must also learn how to “feel” the object in order to know how much pressure to exert because you can’t figure that out just by looking at it.
In addition to creating a prototype of the LUKE Arm with a sense of touch, the overall team is already developing a version that is completely portable and does not need to be wired to a computer outside the body. Instead, everything would be connected wirelessly, giving the wearer complete freedom. Clark hopes that in 2020 or 2021, three test subjects will be able to take the arm home to use, pending federal regulatory approval. For more information and a video on the LUKE arm, visit the University of Utah’s website.
Sources: University of Utah, The O&P Edge
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