Spoiler alert: Luke Skywalker loses his right hand during a duel with Darth Vader (who is also his father, which, in case you’ve lived under a rock, might also be a spoiler). Skywalker’s hand is later replaced by an amazing cybernetic hand, built to perform with incredible agility and looking exactly as his original hand did. Now, he did go on later to lose that hand again, but luckily, Star Wars insurance companies are not as stingy as those we have here, so he was able to get a replacement.
Turn to contemporary, real-life hand prosthetics and often what you see is a relatively clunky system that in some cases is only a small improvement over having no hand at all. The mainstreaming of 3D printing and other 3D technologies, however, has led to the development of better prosthetics, with functionality that goes beyond the aesthetic. Generally, these prosthetics work by receiving signals through electromyogram (EMG) sensors attached to the wearer’s muscles. These sensors detect the presence of the electrical impulses that would normally control the missing hand, but their detection method is relatively coarse, only able to detect the absence of the impulse, not the desired effect.
This means that the prosthetic can be ‘told’ by the signals to open or close a grip, but not to perform the type of fine motor movements we saw with Skywalker’s replacement. Researchers have been searching for a way to program more delicate control into prosthetics, and a group at the Georgia Institute of Technology has just made an important breakthrough. The research team, Gil Weinberg, Minoru Shinohara, Chris Fink, and Levent Degertekin, have been working with amputee Jason Barnes to develop a prosthetic that can move each finger individually. Weinberg described the problem before them:
“EMG sensors aren’t very accurate. 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 eureka moment came when they moved away from EMG sensors and began investigating the possibilities present when using ultrasound to detect muscle movements. The ultrasound was able to detect the differences in muscle movements and report which finger those muscles were directing to move. Creating sensors that could read that output allowed them to build a prosthetic arm that could move each finger individually based on the natural muscle movement of the wearer.
Barnes, who lost his arm below the elbow when he was electrocuted at work, is also a musician and the new hand, which was based on Open Bionics’ open source design, gives him the dexterity he needs to approach the piano again for the first time. As he enthused:
“It’s completely mind-blowing. 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.”
This is not the first ground-breaking prosthetic the team has designed for Barnes, whose first musical love is the drums. Rick Allen of Def Leppard proved that it is possible to play the drums, and play them well, after losing his left arm in a car crash in 1974, so only having one arm didn’t prevent Barnes from continuing his drumming, but the development of a drumming prosthetic certainly let him step up his game. The robotic arm actually holds two sticks, each of which is computer controlled. The first uses the EMG technology and the second has been programmed to listen to what is being played and improvise. Effectively, Barnes becomes a three armed drummer.
Weinberg imagines a day when this type of third arm prosthetic could be utilized even by able bodied individuals who are carrying out complex tasks. There’s no reason that a prosthetic should always be viewed as a simple attempt to recover lost abilities; Weinberg believes that they should push the boundaries and create prostheses that will actually allow the wearer to excel beyond what the able bodied are able to do: run faster, jump higher, and play better. After all, there’s no reason not to push the limits – other than a fear that the prosthetics will one day become sentient and a powerful being from the future will have to travel back to protect us from them. But maybe I’ve just been watching too much TV.
What do you think of this news? Let us know your thoughts; join the discussion of this and other 3D printing topics at 3DPrintBoard.com or share your thoughts below.[Source/Images: Georgia Tech]