Solar Powered e-Skin Could Take Prosthetics to the Next Level

Prosthetic limbs already play a vital role in the lives of amputees by allowing them to do everyday tasks as efficient as possible. But what if an amputee or robot could also acquire the sense of touch? What if it’s also possible to sense the temperature, feel the pressure and sensation of that thing you are trying to touch or hold? Fortunately, a team from the University of Glasgow has turned this ingenious idea into reality by developing prosthetic e-skin.

Dr. Ravinder Dahiya [Image source: The University of Glasgow]

Prosthetic e-skin composition

A paper was published by the team on the 22^nd of March 2017, called “Energy-Autonomous, Flexible, and Transparent Tactile Skin” which describes a new structure of synthetic skin that is able to respond to sensors which make it possible for a prosthetic hand to function more efficiently than a regular prosthetic limb.

The tactile skin is composed of a single-layer of graphene, that is transparent and sensitive, and a photovoltaic cell underneath this layer to act as an energy source which in turn powers the flexible, energy-independent, electronic skin. The transparency characteristic of the graphene layer is advantageous as it enables the photovoltaic layer to efficiently harness light. As the sensitive graphene layer only required a low power source of 20 nanowatts per square centimeter, the photovoltaic area needed to power the e-skin is reduced. Furthermore, the sensitivity of the e-skin was achieved through using an intricate layer of materials. The cleverly structured e-skin patch was then incorporated to a prosthetic hand to test the performance of this newly invented technology.

Gripping ability of prosthetic hand

The research team gave the hand a command to grip a softball which it successfully managed to do. It cleverly grips the ball at a different level of pressure by (A) disabling and (B) enabling the tactile feedback sensor.

[Image source: AFM]

Research Challenges

Although efficiently harnessing energy and supplying the e-skin with electricity to function, one of the setbacks of the photovoltaic cell is that it sources more energy than needed. Currently, the extra energy harvested cannot be stored in the e–skin and the team of scientists are working to come up with ways of diverting unused energy to different storage units such as batteries.

The researchers are also optimistic about finding a way to power the motors of the prosthetic hand and not just the e-skin through the use of photovoltaic cells too. This innovative and ingenious technology also aims to enhance the functionality of robots. This would mean that robot limbs would also possess sensitivity characteristics to reduce errors and avoid human injuries.

Dr. Ravinder Dahiya and his team from the University of Glasgow has made such an important breakthrough in revolutionizing prosthetic limbs by providing it a life-like sensitivity. He is hopeful that the prototype e-skin and limb will be further developed in the next two years.

Source: Energy-Autonomous, Flexible, and Transparent Tactile Skin Carlos García Núñez, William Taube Navaraj, Emre O. Polat, and Ravinder Dahiya*

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