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The Next Generation of Prosthetics

We may think of prosthetics as devices created to enable basic functions, such as walking or grasping an object. Regarded as a necessity, but not an asset, prosthetics of the past have helped their users to meet some of their fundamental needs--but left much that they still weren’t able to experience.

Now researchers are proving that prosthetics are capable of far more than putting one foot in front of the other. The next generation of prosthetics is packing enhanced capabilities and incredible technology; these developments are helping amputees not just live, but thrive.

Feel the Difference

Engineers at Johns Hopkins University have developed electronic skin. Integrating this skin  with a prosthetic hand and allows the user to feel objects with their prosthetic as if they were touching it with their own hand. That includes pain when touching a sharp object!

The design team built their “electronic skin” and placed it over the thumb and index finger of a prosthetic hand. The skin functions using biosensors that are placed in a similar way to the touch and pain receptors in our own skin. They connect those sensors electronically to the nerves in an amputee’s arm, which in turn share those signals with the brain to generate the sensations of touch or pain.

 You might wonder, what’s the benefit of feeling pain in a prosthetic? In addition to providing a full suite of sensations, it also helps wearers to avoid picking up something that would unwittingly damage the prosthesis. 

Affordable Dynamic Solutions

One of the primary difficulties of prosthetics is cost; particularly for families with children who outgrow their prosthesis and have to replace it. The more affordable prosthetics have historically had fewer options and been less customized to individuals.

To help solve that problem, MIT engineers have designed a simple, economic, passive prosthetic foot that can be tailored to each individual user. By taking someone’s body weight and size into account the team at MIT can adjust the shape and stiffness of their foot to create a more appropriate solution for each wearer.

The team created a design framework to use existing user data to predict their natural gait, tailoring the foot to perform in the way that their body naturally expects. The process for this, if manufactured on a large scale, is estimated to be far less than existing similar products.

Take a Closer Look

Prosthetics aren’t just for limbs; one of the most important capabilities is sight, and a team at Fudan University in Shanghai is working to build prosthetics to help your eyes. Macular degeneration and other diseases can lead to blindness, but chemist Gengfeng Zheng wants to reverse those negative effects.

Zheng’s team is using titanium dioxide nanowires coated in gold nanoparticles to create a prosthetic array that has restored the ability to detect changes in light in blind mice. The test for success is quite simple; the rod and cone cells in blind mice were replaced with the prosthetic retina arrays and then light was shone into their eyes. Before the prosthetic, the mice’s pupils did not change when light hit their eyes. After the array was placed the mice’s pupils constricted, indicate that their eyes observed the change in light. This works because the prosthetic absorbs light and creates photovoltage, triggering electrical activity.

While the prosthetic doesn’t enable full color vision, researchers are working to incorporate nanowires that detect the wavelength of light in future versions. Someday this technology could be used in humans to restore sight in full color.

Keep On Your Toes

Athletes are a unique segment of prosthesis market, requiring very specific designs to complete tasks that are difficult even for people who still have all their limbs. Industrial designer Jae-Hyun An has developed a prosthetic leg designed specifically for amputee ballet dancers. The prosthetic leg consists of a 3-D printed socket, a foam-injected molded foot, carbon fiber, a stainless steel toe and a rubber grip toe.

This device is still a concept—Jae-Hyun An is looking for an amputee ballerina to put it into practice—but it emphasizes the design process that athletic prosthetics demand. All of these prosthetic advances are being made because designers and engineers are researching how individuals use their limbs to complete a variety of tasks. The challenge is to create devices that can perform in a myriad of ways, as human muscles can be conditioned to do. These teams are well on their way, with more innovation just around the corner.