Hardware

How 3D printing could make robotic hands more affordable

The start-up that wants to make customised, robotic hands available to the millions of people with missing hands worldwide.

Open Bionics Joel Gibbard holds one of the group's prototype hands.Image: Open Bionics

Human hands can now be replaced using robotics but only at a prohibitive cost.

These bionic hands cost around £20,000 on average - putting them out of reach of many of the 11.4 million people who need them worldwide.

A British start-up wants to reduce that cost twenty-fold, making such hands affordable to a far wider range of people.

"The very first robotic hand I made was at home, just tinkering when I was about 17," said Open Bionics founder Joel Gibbard.

"After doing some research I found it was an area that was really lacking, because the devices that were being developed were far too expensive to filter down to the average amputee.

"So most people weren't wearing them or having access to them, especially kids."

Open Bionics are taking a different approach - building robotic arms using 3D printers.

"As the 3D printing industry grew in the late 2000s, I picked up on it and realised this is perfect for prosthetics because every prosthetic is customised to the individual and using the 3D printer means you can make them really quickly, precisely and each one is different but relatively low-cost," said Gibbard.

Beyond lowering the price of the arm, 3D printing allows Open Bionics to design custom prosthesis. By making prosthesis based on a 3D scan of the residual limb, the firm can create a tightly fitting socket and hand that matches the person's physique.

"When it comes to the hand we can customise the size and shape of that to mirror the amputees other hand, which, for one, makes them look and feel proportioned and balanced."

Unlike traditional manufacturing techniques 3D printing also allows Open Bionics to change the design of each arm, simply by tweaking the digital 3D models.

Gibbard hopes that latitude to play with the look and feel of the limbs will let users stamp their personality on the bionics.

"People love the fact that it's their own, that it's completely customised to them and nobody else has the same one," he said.

A rather dazzling example of how customisable Open Bionics limbs are was on show at a recent Wearables Conference in London, where actress Grace Mandeville was showing off a prosthetic studded with Swarovksi crystals.

Actress Grace Mandeville shows off a prosthetic studded with Swarovksi crystals.

"This is awesome because it looks really cool and I'm really into fashion. An arm that stands out and shows your personality is the best thing ever," Mandeville said.

Open Bionics prototype hands can open and close individual fingers and the thumb. Each finger has an actuator that affords the hand enough movement to allow users to pick up a cup or bottle. Gibbard is confident that people will eventually be able to pinch items between individual fingers and the thumb.

"At the moment we've found you can shake hands with it, people love doing that," Gibbard said.

"We're still working on the grip of the fingers. They're not very grippy at the moment and we haven't perfected the way the fingers close.

"We want it to be really intuitive and really easy to pick up stuff like that. With the next prototype it will be, but we've got a bit of work to do yet."

As well as being dextrous, robotic prosthetics must be light, and it is here that Open Bionics has an advantage over the competition, weighing 250g compared to the 450g - 500g of more expensive models.

Printing a hand and a socket using a Lulzbot currently takes about three days. The hand is printed as "one solid piece of flexible material", which reduces the number of components and saves on manufacturing and assembly time.

Beyond making for a lighter hand, the approach will also allow Open Bionics to vary the flexibility of the finger joints so items can be grasped delicately.

The hand is controlled by muscles in the user's arm or back. Inside the prosthetic are sensors that detect electrical signals being sent to these muscles. Electronics then amplify these signals and translate them into movement commands for the fingers and thumb.

"It works using electromyographic sensors. It's a tried and tested technology in the prosthetics industry," said Gibbard.

"We don't have the power to match human fingers at the moment so you just send it a pulse to say 'open' and it will open stroke and 'close' and it will do the close stroke. It's very intuitive."

Learning how to control the hand takes as little as 10 minutes according to Gibbard, with further time required to become proficient.

Before the arm can be sold the team need approval from medical regulators, but Gibbard is hopeful that an Open Bionics arm could be ready in about one year's time. The team of four is growing and the business has funding from various sources. It successfully completed a crowd-funding campaign in 2013 and took second prize in Intel's Make it Wearable contest last year.

Eventually Gibbard plans to release the designs and software for the prothesis so that universities and maybe the occasional individual could 3D print and tweak the hands.

The team's aim is to gradually reduce the price of hands until they hit their goal of selling for under £1,000.

"It's easier to take the price down than to take it up. I think when we start the process won't be as automated as we want it to be and there will also be designers in the loop for a lot of the process, so it will probably be more like £2,000. It's still a small fraction of the alternative."

Ultimately making a hand that is affordable and that lessens the stigma of wearing a prosthetic, particularly for children, remains an important goal for Gibbard.

"You have kids at school who are shy about their limb difference and it's heartbreaking for their parents to see them grow up being a bit self-conscious. If we can make something that's inspirational for them, a superhero-style robot hand that makes them feel proud about their limb difference, that would be very worthwhile."

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