MOST OF US never think twice about how effortlessly our brain communicates with our limbs. You look, you reach, you grab or step. For many amputees, however, prosthetics are slow and cumbersome, a faint shadow of a healthy arm or leg.
That’s changing quickly through a combination of breakthroughs in the oil, natural gas, and healthcare industries, where a powerful combination of petroleum-based materials, artificial intelligence, and biomedicine provide new mobility and opportunity for their users.
Durable lightweight resins derived from natural gas and oil now form an integral part of a new generation of “intuitive” prosthetic limbs that allow the wearer to reach for objects automatically, without thinking – just like using a real hand or leg. The appendages are also customizable for a tight fit. The plastic materials are easily formed, die cut, machined and fabricated, providing a fresh range of comfort, motion and durability to those who have lost limbs to injury or disease.
In the past, prosthetics were often made of metal or leather, and were clunky and uncomfortable for the wearer. But with innovations using various compounds found within natural gas and oil, the latest generation of durable plastics have changed that, allowing the creation of prosthetic limbs that are strong, light, and a lot more life-like.
Plastics form an integral part of what researchers call an “active prostheses” which can mimic important human characteristics like flexibility, grip, strength, and surface friction. While most of us take for granted how well our brains can relay instructions to our limbs, doctors and engineers have tried for years to grant that same surety to those with prosthetic limbs.
“A limb is a part of your body, and people have an emotional bond with it,” says Jeff Erenstone, owner of Create O&P, which builds 3D prosthetic printing devices that have reduced the time it takes to build and customize an artificial limb down from a few weeks to a few hours.
Erenstone is assisted in his craft through the use of a new generation of thermal plastic urethane (TPU), a soft flexible material that is also strong and durable. Soon, he says, they’ll be able to build prosthetics with different densities — soft in the fleshy areas but more rigid in the center where the bone would be — in order to better replicate the feel of a real limb. Create can also provide prosthetic covers, in more than a dozen different flesh tones, and even imprint a limb with a favorite tattoo.
Researchers in the Netherlands, meanwhile, are also building on the teamwork between the oil, natural gas, and healthcare fields, recently announcing a lightweight and durable prosthetic arm that is clicked directly to the bone, instead of the traditional mounting through a socket system. By meticulously re-routing nerves in the stump into existing, undamaged muscle groups, the patient’s thoughts can trigger a movement in the prosthetic limb. This neuroprosthetic process, called targeted muscle reinnervation, offers a new relationship between thought, signal, and limb that provides a powerful path to mobility.
The installation requires three surgeries. In the first, the surgeon inserts a metal rod into the marrow of the bone. About two months later, the surgeon opens a small hole in the skin and screws a connecting rod into the rod placed earlier. This connecting rod protrudes slightly, allowing a place for the prosthesis to attach. During the third surgery, the nerves and muscles are connected. During rehabilitation , the patient “trains” a practice hand through daily exercises. This helps speed fluidity once the real robotic arm is connected.
Meanwhile, researchers from Newcastle University have created a prototype prosthetic limb mounted with an AI-powered camera that recognizes hundreds of objects. When the wearer moves to grab something, the camera analyzes the object and reacts, moving the hand into a suitable “grasp type” position in one fluid movement. A pinching motion may be needed for picking up a fork, while a bottle requires a vertical grip. The hand ‘sees’ and reacts in one fluid movement.
The lightweight thermoplastic hand is up to 10 times faster than others on the market, say the researchers, and is also inexpensive, using an off-the-shelf Logitech webcam. The AI software can also be trained easily and cheaply. To teach the computer, the researchers created a visual of database of more than 500 objects. Then, each object had 72 images taken, in increments of 5 degrees. The software filters the objects by their features, and learns through trial and error which ones are which. Right now, the user points the prosthetic at the item, induces it to take a photo, and then the arm chooses the grasp and grabs.
Some early challenges remain: the vision-based system still has trouble with crowded backgrounds, and can occasionally be tripped up by distance. But it’s an important start that is reshaping the field of multi-function prosthetics. Working together, an incredible marriage of tech, biology and human ingenuity are aligning in the simple but transformative act of having a prosthetic hand reach smoothly for a simple glass of water.
“It feels very good,” said Erenstone, “to give people back something they’ve lost.”