Every Prototype that Led to a Realistic Prosthetic Arm | WIRED

Key Takeaways

prosthetic arms for much of the 20th and 21st century looked like this while prosthetic legs were running in the olympics arms were being left behind prosthetics uh it's a quite a challenging product to develop it's not going to replace or or surpass a human hand it's a tool ultimately and it's there to assist you and we have to make it extremely functional but easy to use but since the early 2000s private companies governments and research labs are developing prosthesis that are more functional and a lot more advanced than previous designs wire talk with easton la chapelle founder and ceo of unlimited tomorrow to understand how he designed tested and adopted his prosthetic arm so what are the options available for those looking for prosthetic arms the landscape of prosthetic offerings today is quite a spectrum there's very simple passive devices they look like a hand but they don't have any type of movement or function beyond just aesthetics or cosmetics the next here is the body powered so this is the classic kind of hook and claw system usually you shrug your shoulder kind of move your body to be able to close an open claw and then the next class is quite a wide one you go into the myoelectric more robotic class and then beyond that you get into the research level where these are these brain control devices that universities are developing so the big question was how can you design an arm that's functional while also being affordable easton started with this design this is really what started it all this is the very first robotic hand i made when i was 14 and as you can see there's a lot of simple household items it's a lot of legos and electrical tubing at this point it's very very basic but this essentially validated that we could use motors and tendons to open and close fingers next was this model i made this back in 2012 and this was really the infancy of the consumer 3d printing world you know these were essentially kind of hot glue machines that extruded material and sometimes they work sometimes they didn't you can see it's a very similar concept where we have these servo motors that essentially pull these tendons these fishing lines for the increased grip i i decided to put these little finger pads and this was was far more functional i could actually pick up things accurately and do a little bit more real-life tasks with it their next prototype was a little more sci-fi it used an eeg headset which measured brain waves to control the prosthesis so the next prototype is what i call robo arm and this was a lot of the concepts kind of rolled into one here i found a lot of benefit working with pendant systems compared to other mechanical designs a lot of other devices on the market use linkages and so then when we looked at tendons and especially the individual finger joints essentially we want to eliminate the cognitive bandwidth that someone uh experiences when using a prosthesis and an experiment with how do we merge mana machine can we tap into the brain without a surgery do you know can we use external headsets or is it best to go into the nerves the muscles kind of the area to be able to control the prosthesis their next design went back to the basics getting rid of the headset and focusing instead on a 3d printed material with a tendon system design so this is like i'm learning from years of prototyping bundling it all into a single design here the socket is the hardest part of a prosthesis and if it doesn't fit right no one's going to use it and this was actually replica for a small grow name momo we would send webcams and 3d scanners and xbox kinects down to her house in florida where her mother would scan her residual limb and then we would generate a socket which is how the device attaches to the person and then there's a small band that would read your muscles and then from there she's able to open and close the hand change the grips we still utilize today of how can we create these natural feedback loops to the brain we want to supplement the brain we don't want to take control or to create a secondary brain we want to we want to tap into exactly how a human arm typically works this is true limb this is our first product we launched in june of 2020 and when you look at this this is essentially a robotic hand so each of these fingers have individual finger motion you can see these small tendons in here we have about 14 joints that act independent so how does it work how can people with missing limbs use their muscles to move the device it's one thing to read data from the human body which we do through sensors but then how do we input data back into the body and into the brain how do we provide feedback of are you touching something that's hot or cold are you picking up something with delicate touch or are you actually really grasping it it starts here with their feedback system we wrap the entire limb with with a large array of these sensors and we look for very small minute changes we try and go as simple as possible right now we use a vibration motor similar to what's in cell phones the use of 3d printed materials helps keeps costs down but in the beginning the 3d printed landscape looked a lot differently than today 3d printing has come a long way since i started uh back when some of the most simple 3d printers made out of laser-cut wood and very simple plastic it looks incredible but what we're finding is that it's very brittle and so we kept having the pinky break it's what you're going to bang everything against on a counter and we kind of reach the point where like this is just not going to work for a prosthetic device it's just not durable enough and then so we started looking into what's happening in the landscape of 3d printing and it's actually where we first started talking with hp they created this incredible machine that prints in full color but also in a very strong nylon material innovations in 3d printing meant stronger materials which hopefully translates to more resilient devices so what's next for unlimited tomorrow we're constantly learning constantly doing research data collection that helps influence the future the product and so that's something that's really high on our list is just to continue to expand and just you know just make this more and more accessible and we're looking at forms of exoskeletons and other types of technology uh to use robotics and a lot of our foundational technology to you know help help give people uh you know empowerment and accessibility and mobility across the world