Scientists Create First Prosthetic Arm That Transmits Sensation: 'You Can Feel Your Partner Hold Your Hand'

After losing her arm in a motorcycle accident, Claudia Mitchell worked with a research team to test a new bionic arm that can feel sensory stimulation

Claudia Mitchell
Photo: Courtesy Cleveland Clinic

Claudia Mitchell had been out of the Marine Corps just a few months when she hopped on the back of a friend's motorcycle in 2004. He lost control of the bike, and Mitchell ended up losing her kidney, spleen and left arm at the shoulder. She was only 23.

"It was actually the best time in my life to have something like that happen," says Mitchell, who lives in Barling, Arkansas. "I was fresh from the Marine Corps and felt like I could do anything. I was optimistic. I was old enough that I was confident, yet young enough to be bold and brazen."

She got her first prosthetic arm through the VA in 2005. "They did the very best they could with the technology that was available at the time," she recalls. "But for a shoulder amputee it was really hard to control the arm. I would get frustrated and end up not wearing it."

Mitchell read an article about research being conducted in Chicago to develop more advanced prostheses. She laughs remembering how she just decided to call the hospital and ask if she could be involved. Somehow, she says, "the stars aligned" and she was accepted as a research participant.

Claudia Mitchell
Claudia Mitchell

Over the next few years, Mitchell underwent targeted sensory and motor reinnervation, procedures that redirect amputated nerves to remaining skin and muscles. She was introduced to Paul Marasco, Ph.D., who she calls the "Nerve Guru" but whose actual title is associate professor in Cleveland Clinic Lerner Research Institute's Department of Biomedical Engineering.

Dr. Marasco and his Cleveland Clinic research team of scientists, engineers and mathematicians spent more than a decade trying to improve functionality in prostheses. Currently, most are controlled by muscle function — amputees have the ability to open and close a hand, for example, but can't actually feel anything.

"I still don't know what my hand is doing unless I'm looking at it," says Mitchell, who has worked alongside Dr. Marasco's team to test a first-of-its-kind sensory arm. "His team built sensors into the hands, so I can feel when someone is touching my thumb, my pinky, my ring finger — with my eyes closed. The new technology allows me to hold a paper cup of coffee and not squeeze it so hard and spill it everywhere without having to look at it."

According to the Cleveland Clinic, the bionic system enables patients to send nerve impulses from their brains to the prosthetic when they want to use or move it, and to receive physical information from the environment and relay it back to their brain through their nerves. It allows prosthetic limb wearers to think, behave and function like a person without an upper-limb amputation.

"We modified a standard-of-care prosthetic with this complex bionic system which enables wearers to move their prosthetic arm more intuitively and feel sensations of touch and movement at the same time," Dr. Marasco said.

Claudia Mitchell
Courtesy Cleveland Clinic

"We built the system actually using an off-the shelf prosthetic as our basis but then we put in high-level computing and touch sensation and movement sensation," he says. "So when you look at the limb itself, it looks like any other limb — you can't tell there's actually a highly sophisticated computerized communication and feedback system running inside of that."

Explains Mitchell: "It allows me to shake your hand without hurting you — to know when to stop squeezing. And I can still maintain eye contact. Do you know how important that is when you meet somebody new? You want to look them in the eye but you can't if you have to look at the hand to make sure you don't hurt them!"

Once on the market, the arm will make a huge difference to amputees like Mitchell. "This goes from being a tool that is on your body, like a drill or a hammer, to being part of your body," she explains.

"If your partner is sitting on the couch beside you, you can actually feel them reach over and hold your hand," Mitchell says.

"Having this touch response and ability to get the feedback is phenomenal. Touch is such a fundamental thing — you don't know how important it is until you lose it."

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