‘FLEXIBLE’ and ‘thin’ are two significant words which have been used to describe a revolutionary new artificial skin that can sense pressure and relay this information to the nervous system. A realisation of a decade’s worth of research, the new plastic material created by Prof Zhenan Bao and her colleagues at Stanford University, Stanford, California, USA, may eventually lead the creation of prosthetic limbs with the ability to feel touch sensations.
“This is the first time a flexible, skin-like material has been able to detect pressure and also transmit a signal to a component of the nervous system,” said Prof Bao. “We are able to use a sheet of plastic to mimic the human skin’s sensing ability, and it can generate electrical signalsShe added that the signals may be directed into the nervous system, concluding: “It is not the first pressure sensor that can communicate with the brain, but it is the most skin-like.”
The new artificial skin contains two layers: a top layer that contains the sensing mechanism, and a bottom layer that works like a circuit: sending electrical signals and translating them into messages for nerve cells. Billions of pyramid-shaped carbon nanotubes spread throughout the plastic and an embedded waffle pattern allow a high degree of sensitivity across a range of pressures. Similar to skin, an impulse is created when the plastic is deformed by compression; however in this case, electrical conduction occurs when the nanotubes are brought closer together. Using a technique developed by a pioneer of optogenetics, Prof Karl Deisseroth, Professor of Bioengineering, Stanford University, the team were able to prove that the electrical signals produced by their artificial skin can be recognised by a biological neuron. This testing was carried out using slices of brain cortex from murine models, during which the electronic pressure signals from the artificial skin were translated into light pulses. Once relayed, these light pulses activated the neurons.
Though there is still much work to be done, the researchers are optimistic about the promise of this new invention. In the future, they would like to create different sensors that could give prosthetic limbs the ability to differentiate between different textures: for example, corduroy and silk. “This work represents a step toward the design and use of large-area organic electronic skins with neural-integrated touch feedback for replacement limbs,” concluded the authors in their paper.