Using a strategy that, if perfected, could give hope to millions of people with prosthetic limbs, Stanford University scientists have developed soft and supple electronic skin that can communicate directly with the brain by mimicking the sensory feedback of real skin.

“We were inspired by a natural system and wanted to emulate it,” said Weichen Wang, whose team published their achievements in the journal. Science. “We may one day help patients regain not only their motor function, but also their senses,” says Techxplore.com.

Much faster, larger and more complex circuits are needed to make the so-called “e-skin” suitable for humans. But an important milestone was the extraordinary success of the device in laboratory rats. When the researchers pressed the mouse’s electronics against its skin and sent electronic impulses to its brain, the animal responded by shaking its leg.

Scientists have long dreamed of creating prosthetic limbs that not only restore movement but also provide perceptions such as pressure, temperature and vibration perception to help restore a more normal quality of life. Skin damage and amputation lead to significant disruption of the perception and movement cycle, making even simple tasks such as sensing or grasping an object difficult.

“If you take a glass of beer and it doesn’t feel like it’s cold, you don’t taste right,” said Ravinder Dahiya, a professor of electrical and computer engineering at Northeastern University in Boston. also examines the use of flexible electronics to develop artificial skin

Electronic skin can also be used to dress robots so they can feel sensations just like humans. This is critical to the safety of industries where robots and humans physically interact, such as the delivery of tools in production.

But the sense of touch is complex. Human skin has millions of receptors that sense when poked, pressed, squeezed, or boiled. They respond by sending electrical impulses to the brain via nerves. The brain responds by sending back the information and tells the muscles to move.

And biological skin is soft and can be stretched many times over decades.

The Stanford team, led by chemical engineering professor Zhenan Bao, has been working on the design of the electronic skin for several years. But the previous attempt used 30 volts of power, which is dangerous and requires solid electronics and 10 batteries. And it could not withstand constant stretching without losing its electrical properties.

“The challenge was not to find mechanisms to mimic the exquisite sensory abilities of human touch, but to assemble them using only leather-like materials,” Bao said in a statement. Said.

The new electronic skin is innovative as it uses mesh layers of stretchable organic transistors that sense and transmit electrical signals. When folded, the layers are only 25 to 50 microns thick; as thin as a sheet of paper, like leather. Their mesh functions as sensors designed to detect pressure, temperature, voltage and chemicals. They convert this sensory information into an electrical impulse.

And e-skin works with only 5 volts of electricity.

To test the system, the Stanford team placed it in a live mouse. Touching the mouse’s electronic skin sent an impulse through a wire into the mouse’s brain, specifically to an area called the somatosensory cortex, which is responsible for processing physical sensations. The mouse’s brain responded by sending an electrical signal to its leg. This was done using a device that amplifies signals from the brain and transmits them to the muscles, simulating connections in the nervous system called a synapse.

The mouse’s paw twitched. More importantly, its movement corresponded to different levels of pressure, said Ph.D. and the first author of the new article. For example, the team could increase the movement of the leg by pressing harder on the electronic skin, which increases the frequency of the signal and the output of the transistor.

If tested on humans, the device would not require a wire to be implanted to send sensory information to the brain. Instead, the team envisions using a wireless connection between the electronic skin and an electrical stimulator located next to the nerve.