First woman fitted with bionic arm
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Date posted: 15/09/2006
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Ex-Marine Claudia Mitchell lost her arm in a motorcycle accident two years ago. Since then, she struggled with life with one arm. As Mitchell relayed, the first time she tried the simple task of peeling a banana with one arm, she had to grip it between her feet, and peel it like a primate ? the emotional impact of that was devastating.
The 26 year old has been fitted with a prosthetic arm before, but the standard cosmetic-only bionics usually on offer, did nothing to aid her life. Now, she is the first human trial of a bionic arm, developed at the Rehabilitation Institute of Chicago.
Claudia Mitchell with her new arm
Drawing on the plethora of BMI research over the past decade, the new arm bends and flexes, and responds to subconscious nerve impulses just like an organic arm.
Dictionary Term: BMI
BMI stands for Brain-Machine Interface, and represents an old field, of connecting the human brain to machines, which drifted along for decades, then experienced a massive boost to development speed in 2000+, and is currently growing with exponential speed, with real successes in linking human brains to computers, and the control of virtual, and physical prosthetic limbs via pure thought control.
The U.S. Defense Department plans to leverage Mitchell?s services in helping military amputees adjust to bionic arms like hers, which it plans to begin offering this year to soldiers who have lost limbs in Iraq and Afghanistan.
If they do as well as Mitchell, who finds she can move her elbow and her wrist at the same time, which is a massive step forwards for prosthetics ? never been done before ? then it promises to bring back mammoth quality of life.
Mitchell said she simply has to think to move her arm, a far cry from her first replacement limb, which was so hard to work that she gave up in tearful frustration.
"I can flex my elbow, extend my elbow, open and close my hand with the mere thought of doing it," she said of her new arm Tuesday while in Chicago to help Rehabilitation Institute researchers test an even more advanced thought-controlled prototype. On Wednesday the team was in Washington, D.C., to show the experimental model to military brass.
"I can carry a tray," Mitchell said. "I can open a jar. I can hold my Dagwood sandwich. I can hold fruit and vegetables while I cut them up. I can peel a banana.
"This makes daily life much easier, especially in the kitchen; that's where I found the most difficulty in doing things with one hand. So I am much more adept in the kitchen now, which my family is pretty excited about."
The arm works well enough by pure thought to cook with
The bionic arm weighs about 6 pounds and costs between $60,000 and $75,000. She said she typically wears the arm two to eight hours a day.
How it works
The human arm is connected to the central nervous system by four main nerves, which betweeen them, control all joint movements and positioning. Instead of communicating with a missing arm, the stubs of these nerves are re-routed from the arm stub and into the chest, where they can be assured a plentiful blood supply. The ends of these nevers and then fixed to sensors, which pick up the most delicate electrical activity, and passthat to a computer, which works out what the signals are asking for.
"This arm feels very natural as far as the way I can flex and open and close my hand," said Mitchell, who served in the Marines for four years and is now on inactive reserve. "The first prosthesis I had, my frustration was out the roof. I would cry. It was extremely frustrating to the point where I wouldn't wear my arm. With this arm, all I have to do is think. I think I want my arm to go down, it goes down. I want my arm to go up, and here I go."
The prosthetic limb, in its current state perovides no haptics, no tactile, temperature or pain response back to the body.It is strictly one way, rading from the nervous system, not writing to it. However, prograss is being made towards that goal.
Earlier this year the defense agency awarded nearly $50 million to two teams of researchers with the goal of providing the most advanced medical and rehabilitative technologies for military personnel injured in the line of duty. Rehabilitation Institute scientists are working with both teams.
One of the teams, led by the Applied Physics Laboratory of the Johns Hopkins University, will work on a bionic arm that can operate like a biological one, including the ability to feel objects and manipulate them with precise movements. The second team, headed by DEKA Research and Development Corp. in Manchester, N.H., will focus on providing near-human strength to the artificial arm.