Artificial skin that sends pressure sensations directly to brain cells has been developed for the first time, bringing the eventual goal of flexible, healing and feeling artificial skin a step closer.
Developed by Zhenan Bao, professor of chemical engineering at Stanford, the skin is able to detect the level of pressure applied to it, be it a light touch or a hard press.
Bao, who has been working on the development of artificial skin for a decade, led a team of 17 researchers to create the technology, which has been detailed in an article published today in the journal Science.
“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,” she said.
Bao aims for the skin, which is designed to fit over a prosthetic limb, to eventually be able to heal, signal pain and detect touch and temperature.
The artificial skin is made up of two layers of plastic, with the top layer providing sensing capabilities and the bottom sending the data to nerve cells as electrical signals.
The top layer’s sensing abilities are achieved by giving the plastic a waffle pattern, which makes the plastic very sensitive to pressure, and then dispersing billions of carbon nanotubes throughout it.
These nanotubes conduct electricity when squeezed together, so when pressure on the skin increases, the nanotubes are pushed closer together, and more electricity is conducted.
The second layer, which takes the form of a flexible electronic circuit, then transmits this electricity to nerve cells in pulses, allowing the level of pressure to be determined.
This is designed to mimic the way real human skin works, as our own awareness of pressure is the result of our brain interpreting short pulses of electricity in a similar manner.
The have not yet directly tested the skin by hooking it up to a human brain, however. Instead they took inspiration from a field known as optogenetics – where optics and genetics meet – to generate an artificial version of part of the human nervous system, which they signalled by transferring the electrical signals into pulses of light.
While this was an effective proof of concept, in the long run the researchers plan to use a different approach to directly stimulate human nerves with the electrical pulses. They are confident this can be achieved as other researchers have already found ways to stimulate neurons directly with such pulses.
There is still considerable work ahead before Bao’s dream of fully sensory artificial skin can be realised, but this work is an exceptionally important step along the way.
“We have a lot of work to take this from experimental to practical applications,” she said. “But after spending many years in this work, I now see a clear path where we can take our artificial skin.”
With just two layers in the current system, the researchers believe it will be easy to add additional sensors as they are developed.
Among those the researchers want to create are sensors to determine different textures, allowing the wearer to differentiate between fabrics, for example, and sensors to determine the temperature of an object.