If you lost your hand in an accident today, you’d be faced with a choice: fork out thousands of dollars for a high-end bionic replacement, or manage with a low-tech option. For most amputees, “Door A” isn’t one they can afford to walk through, leaving them no choice but to adapt to a life without fingers or the very thumb that defines us.
Now, 25-year-old robotics graduate Joel Gibbard and his team at Open Bionics are attempting to create a third option: a 3D-printed, robotic hand called the “Dextrus.”
“The aim of the the project is to make prosthetics more accessible to the people who need them most,” says Gibbard. “At the moment, these devices do exist, but they can cost up to $100,000 and aren’t typically covered by national health services or insurance policies. The Dextrus can offer comparable functionality to the leading prosthetic hand, at a one-hundredth of the cost.”
Rather than using expensive materials like carbon fiber or titanium, the team 3D-prints Dextrus’ bones in ABS plastic. This process not only makes them cheap (ultimately, the hands will be sold for just under $1,000), but also makes them easy to reproduce. An entire prosthesis can be printed in just 40 hours, which could be a game-changer for patients who would otherwise wait weeks, or even months, for their new limbs.
In addition to plastic, the soft robot is made up of electric motor muscles, steel cable tendons, and a flexible, TPU skin to help form a more-natural grip. Each finger is then fitted with a feedback-sensor, which gives the hand a sense of touch, much like our own.
“When someone grabs an object they don’t have to think about moving each finger to the exact position it needs to be in to grasp it,” says the team. “Instead we simply think ‘close the fingers until they come into contact with something, and then stop.’ The Dextrus hand works in the exact same way. By using feedback sensors as the fingers close, it knows when it is gripping an object and how hard it’s gripping. You just have to tell it to when to close and open.”
The system enables Dextrus to perform fine-pinch grips on delicate objects, which has makers like Chef Liam Corbett, who’s been using a prosthetic hook since he lost his hand, feeling optimistic.
“Peeling things… that’s what I miss,” he says. “To most people it’s a bit of a boring job, but it’s something that needs to be done. I couldn’t do that with my hook. I’d be proud to wear this. I think it could give me back the finer things in life. And my confidence.”
Dextrus relies on myoelectric signals, the signals produced by our muscles, to determine what a user needs. “These signals can be detected on the surface of the skin,” explains Gibbard. Electrodes placed on the shoulder pick up the signals and send them to electronics in the hand, which interpret the information and work out which movement is most appropriate.
The most exciting thing, perhaps more than the device itself, is that Gibbard and his team plan to keep the hand open-source, meaning everything you need to make it will be published online. “There are no patents, anyone has the right to make their own,” he says. “I originally designed this as part of a project at the University of Plymouth. At the time what I didn’t realize is that it takes more than just great research to make a real difference. you have to take the technology out of the lab, and put it into the  hands of the people that need it.”
Check out more amazing images of Dextrus, including a Starkified version that warms the cockles of my nerdy heart, in the gallery below.
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IMAGES: Open Bionics
