Although prosthetic arms have been on the market for some time now, researchers at the Georgia Institute of Technology have come up with one that enables amputees to control their prosthetic fingers individually. This is a major breakthrough, providing users with the fine motor hand gestures that have not yet been achieved by commercially available devices. Jason Barnes, 28, is now able to play the piano for the first time since the amputation of his right arm five years ago.

“Our prosthetic arm is powered by ultrasound signals,” said Gil Weinberg, the Georgia Tech College of Design professor who heads the project. “By using this new technology, the arm can detect which fingers an amputee wants to move, even if they don’t have fingers.”

Most prosthetic arms use electromyogram sensors, which rely on electrodes to pick up electrical signals from the muscles. But according to Weinberg, this set up is not without problems.

“EMG sensors aren’t very accurate,” he says. “They can detect a muscle movement, but the signal is too noisy to infer which finger the person wants to move. We tried to improve the pattern detection from EMG for Jason but couldn’t get finger-by-finger control.”

The team then attached an ultrasound probe to Barnes’ arm, which allowed them to see how his muscles moved and allowed them to distinguish between movements intended for each finger. By feeding these unique movements into an algorithm, the system was able to predict which finger Barnes wanted to move, and even how much force he wanted to apply.

“It’s completely mind-blowing,” said Barnes. “This new arm allows me to do whatever grip I want, on the fly, without changing modes or pressing a button. I never thought we’d be able to do this.”

As a homage to Luke Skywalker’s bionic arm, Barnes performed the Star Wars theme song with the new prosthetic.

“If this type of arm can work on music, something as subtle and expressive as playing the piano, this technology can also be used for many other types of fine motor activities such as bathing, grooming and feeding,” said Weinberg. “I also envision able-bodied persons being able to remotely control robotic arms and hands by simply moving their fingers.”


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