Graphene 'electronic skin' could harness solar power to return sense of touch to amputees

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Photo of Dr Ravinder Dahiya with robot hand

Dr Ravinder Dahiya

Engineers at the University of Glasgow have utilised graphene to develop a solar-powered 'synthetic skin' that could be used to create advanced prosthetic limbs for amputees.

The Bendable Electronics and Sensing Technologies (BEST) group, led by Dr Ravinder Dahiya, believe their breakthrough could see 2D material graphene's physical properties utilised to harvest energy from the sun to power the skin and return the feeling of touch to amputees.

Their work was supported by the Engineering and Physical Sciences Research Council (EPSRC), and Dr Dahiya is also the recipient of an EPSRC Engineering Fellowship for Growth. It has generated global interest, with media organisations across the planet publishing articles.

The BEST group's findings are published in a research paper published in the Advanced Functional Materials journal, which details how they have integrated power-generating photovoltaic cells into an 'electronic skin' made from graphene for the first time.

Graphene is a highly flexible form of graphite which, despite being just a single atom thick, is stronger than steel, electrically conductive, and transparent. It is graphene's optical transparency, which allows around 98 per cent of the light which strikes its surface to pass directly through it, which makes it ideal for gathering energy from the sun to generate power.

Dr Dahiya, from the University of Glasgow's School of Engineering, said: 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.

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. Those measurements mean the prosthetic hand is capable of performing challenging tasks like properly gripping soft materials, which other prosthetics can struggle with. We are also using innovative 3D printing strategies to build more affordable sensitive prosthetic limbs, including the formation of a very active student club called 'Helping Hands'.

Skin capable of touch sensitivity also opens the possibility of creating robots capable of making better decisions about human safety. 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 new skin requires just 20 nanowatts of power per square centimetre, which is easily met even by the poorest-quality photovoltaic cells currently available on the market. And while energy generated by the skin's photovoltaic cells cannot be stored yet, the team are already looking into ways to divert unused energy into batteries, allowing the energy to be used as and when it is required.

Dr Dahiya added: 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.

We've already made some encouraging progress in this direction and we're looking forward to presenting those results soon. We are also exploring the possibility of building on these exciting results to develop wearable systems for affordable healthcare. In this direction, recently we also got small funds from Scottish Funding Council.

Reference: PN 22-17