Scientists Create Solar-Powered Skin for Prosthetic Hands

Using solar power as an energy alternative has always been considered an environmentally sound option. Now, scientists have created a new use for the sun’s rays.

Engineers from the University of Glasgow have created electronic skin made from graphene — a flexible, material-made graphite — to cover prosthetic hands. The material is considered to be stronger than steel and conducts electricity.

The skin has a transparent, touch-sensitive layer that allows it to absorb 98 percent of sunlight that passes through its surface. Study lead Ravinder Dahiya said attempting to recreate human skin’s properties was a challenge for him and colleagues in his Bendable Electronics and Sensing Technologies (BEST) group.

“Human skin is an incredibly complex system capable of detecting pressure, temperature and texture through an array of neural sensors which carry signals from the skin to the brain,” Dahiya said in a press release. “My colleagues and I have already made significant steps in creating prosthetic prototypes which integrate synthetic skin and are capable of making very sensitive pressure measurements.”

Dahiya said the measurements allow a prosthetic hand to properly grip soft materials, which other prosthetics often struggle to do. Dahiya and the BEST group were able to place cells that generate power, called photovoltaic cells, within the electronic skin.

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The team is working to use 3D printing as a way to create affordable and sensitive prosthetic limbs with the help of a student club known as Helping Hands, Dahiya said. Thanks to the skin’s transparent layer and sensor cells, it is sensitive to touch and can withstand a broad range of pressure.

The skin requires only 20 nanowatts of power per square centimeter, a standard that can be met by the worst photovoltaic cells on the market. The energy harvested cannot be stored, but Dahiya and his team are working to implement a battery system for the skin.

“The other next step for us is to further develop the power-generation technology which underpins this research and use it to power the motors which drive the prosthetic hand itself. This could allow the creation of an entirely energy-autonomous prosthetic limb,” Dahiya said.

The study was able to test the skin by taking patches, integrating them onto prosthetic hands and observing its responses. The sensors’ stimuli were evaluated by a series of tasks, such as touching and grabbing soft objects.

“Skin capable of touch sensitivity also opens the possibility of creating robots capable of making better decisions about human safety,” Dahiya said. “A robot working on a construction line, for example, is much less likely to accidentally injure a human if it can feel that a person has unexpectedly entered their area of movement and stop before an injury can occur.”

The study was funded by the Engineering and Physical Sciences Research Council and the Scottish Funding Council. It was published in Advanced Functional Materials.

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