Modern prosthetics can have a wide range of motion and allow users to control them via residual muscle signals to perform desired movements with thought alone. Once in the realm of sci-fi, these bionic limbs show that the future is already here – for those who can afford it.
In an effort to make a prosthetic limb that is both highly functional and accessible, researchers at MIT and Shanghai Jiao Tong University have designed an inflatable neuroprosthetic hand that allows users to perform very complex movements such as pouring. juice from a container or close a suitcase. While similar neuroprostheses cost over $ 100,000, this inflatable hand can be made for as little as $ 500.
“It’s not a product yet, but the performance is already similar or superior to existing neuroprostheses, which we are excited about,” says Xuanhe Zhao, professor of mechanical and civil and environmental engineering at MIT. “There is enormous potential to make this prosthesis flexible at a very low cost for low-income families who have had amputations. “
The soft prosthesis is made from a soft, stretchable material – an elastomer known as EcoFlex. The soft and elastic properties allow the prosthesis to be both lightweight at just half a pound (225 grams) and very durable, with tests showing it can return to its original shape after being crushed by a hammer or crushed by a car.
Each of the five balloon-shaped fingers wraps around fiber segments that replace articulated bones. These numbers are connected to a 3D printed “palm” in the shape of a real human hand. Rather than using complicated and heavy electric motors, the fingers are articulated using a pneumatic system consisting of a small pump and many valves that must be worn around the waist.
Users can form four main types of grips: pinching two and three fingers together, making a ball fist, and cupping the palm. The prosthesis user can use a combination of these four basic movements to perform various hand movements that are useful in everyday life. Gripping actions are facilitated by a tactile feedback system, which includes pressure sensors on each fingertip, so the user can get a feel for how much pressure they are exerting on an object and adjust it accordingly. .
The movements themselves are controlled by muscle signals which are translated by computer algorithms into instructions that the prosthesis controller can understand.
The inflatable hand has only been tested in two volunteers who have had an upper limb amputation so far. Each participant first followed a brief 15-minute electromyography (EMG) training session, using sensors that record electrical signals from the residual limb. This way, when the user imagines shaking their hand in a fist, the prosthesis reacts accordingly.
Despite the small sample of volunteers, the prosthesis worked wonderfully. Participants used the inflatable hand to write with a pen, turn the pages of a book, eat foods like crackers and cakes, and lift objects of different weights. Compared to commercially available bionic hands, the inflatable hand performed on par or better.
The researchers have filed for a design patent and hope to bring the product to the market soon. There are more than five million people around the world who have had an upper limb amputation, and such a cheap but functional prosthesis could dramatically improve their quality of life.
In the meantime, Zhao and his colleagues plan to tweak and improve the design so that it is suitable for mass production. Over time, this kind of remarkable technology could become the norm. For example, philanthropist and entrepreneur Tej Kohli’s “Future Bionics” program highlights how assistive technology can dramatically improve the quality of life of people with disabilities.
“We now have four types of catch. There may be more, ”Zhao says. “This design can be improved, with better decoding technology, higher density myoelectric networks and a more compact pump that could be worn on the wrist. We also want to customize the design for mass production, so that we can translate the soft robotic technology for the benefit of the company. “
The inflatable bionic hand was described in a recent study published in the journal Nature Biomedical Engineering.