According to a current WHO estimate, more than 100 million people worldwide need a prosthesis or orthosis, and 9 in 10 of them have no access to these relatively expensive devices. Several organizations are currently trying to fill this dramatic medical supply gap with the help of 3-D technology.
Born without fingers on his right hand, 6-year-old Julian used to hide this part of his body on family photographs. That is, until he met Perry Weinthal, Chad Coarsey and Manny Papir from The Bionic Glove Project (BGP) in 2015, who gave the little boy from Florida a 3-D-printed mechanical hand. Julian quickly outgrew the first device and is now on his second bionic hand, which BGP made in his favorite colors including parts that glow in the dark. BGP told us:
He is proud to show his hand off now.
However, just as he will periodically need bigger shoes, Julian will periodically have to get another hand. Maybe as many as 20 before he’s fully grown. Luckily, BGP can manufacture 3-D-printed hands at a relatively low price:
“Our devices are in the hundreds of dollars. We only need a few measurements and about a week to make a hand. Without 3-D printing this would not be possible. It is an additive technology as opposed to reductive technologies, which are extremely wasteful, and it allows us to use low-cost materials.”
By contrast, classically custom-made prosthetic devices can take weeks or even months to produce and easily cost several tens of thousands of dollars, with most health insurance companies only covering one per patient if at all. According to BGP, this is especially an issue for young children as they can out-grow a hand every four months. For adults the issue centers around the fact that their muscle anatomy can change by using a new prosthetic. BGP has seen adult forearms grow as much as 12% from regular use of their hands.
We look at this as training wheels. Our devices are tools to teach children and young adults how to use prosthetics
“Prosthetists create wonderful works of art, but children are not viable clients at that point. We are talking a cost nearly equivalent of a car every quarter or semester and not many families can afford that. Also, Julian’s parents used to ask, ‘What if he breaks it?’ But thanks to rapid prototyping, we now have an inventory of parts, and we can replace anything on a given hand right away. We don’t discourage breaking of hands, because it means that they are out there using it, and that’s a good sign.”
At the same time, BGP says they are not trying to compete with the prosthetics industry: “We look at this as training wheels. Our devices are tools to teach children and young adults how to use prosthetics, as well as keep their bone and muscle growth bilaterally equal. So when they reach adulthood they have the capability of running a high-end prosthetic, if they want to.”
It Works Like a Pulley
The design for the 3-D-printed bionic hands BGP has made for Julian and about 15 other patients is based upon open source files from the e-NABLE Community. Users control the flexion and extension of the fingers by moving their wrists:
“It is totally mechanically powered and works just like a pulley, when you have a rope around a ring and pulling a bucket. Imagine that bucket being the fingers and the rope is tied around each of them. As you pull the rope by bending the wrist, you are pulling the fingers to tighten and can grasp things.”
The vast majority of the parts in a BGP-made mechanical hand are 3-D-printed: “We use some external hardware, such as the padding, the straps, or the cables, and some screws. But everything else is 3-D-printed, using polylactic acid (PLA).”
Other 3-D prosthetic developments from the e-NABLE community, such as the Cyborg Beast hand, are made from acrylonitrile butadiene styrene (ABS), which is also the material used to create Lego construction toys. The costs for a Cyborg Beast hand can be as low as $50 USD.
Adding Robotics Into the Mix
While the BGP and Cyborg Beast hands are examples of 3-D-printed mechanical prostheses, there are also organizations that add robotics into the mix, such as Exiii’s HACKberry, which costs around $200 USD, or Dextrus, by the Open Hand Project. Open Hand Project founder Joel Gibbard explained in the Dextrus crowdfunding video:
The aim of the Open Hand Project is to make robotic prosthetic hands more accessible to the people that need them.
“At the moment these devices do exist, but they can cost up to $100,000 USD. The Dextrus can offer comparable functionality to leading prosthetic hands, at one-hundredth of the cost,” he added.