Researchers at Stanford University have developed a synthetic skin-like device capable of picking up pressure sensations and relaying them to the brain. Zhenan Bao, a professor of chemical engineering at Stanford, was the lead researcher. She has been pursuing the project for 10 years.

The research of Bao’s 17-person research team was reported earlier this month in the journal Science. Like real skin, the pseudoskin device is composed of layers. The top one is defined by its sensor — capable of sensing the same range of pressure as undamaged human skin is. The second layer contains the circuit to transmit electrical signals from the sensor and convert them to biochemical impulses — the language of nerve cells.

“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,” Bao told Tom Abate of Stanford Report.

The team’s research five years ago was centered on detecting the elasticity of plastic and rubber materials on the molecular structure level. From there, they increased the flexibility and pressure sensitivity by forming the pliable plastic into a waffle shape, according to Abate. The electrical component depends on billions of carbon nanotubes, embedded in this waffle pattern. When pressure is applied to the plastic, the nanotubes press together, increasing the amount of electricity moving through the structure.

The lightness of touch corresponds directly to the amount of electricity being conducted — a firm handshake compresses the plastic more, bringing correspondingly more nanotubes into contact, and causing a greater amount of electricity to flow through the structure.

When it came to connecting the second layer, bioengineering entered the picture — the ambitious project represents a feat of both electrical and biological engineering. The research team adopted Stanford bioengineering professor Karl Deisseroth’s method: optogenetics. In this technique, according to Abate, nervous cells are engineered to respond to particular light frequencies. These frequencies were then achieved by translating the electric pressure pulses into the requisite light pulses.   

According to Bao, optogenetics is just a launching point. The team hopes to develop a method of directly simulating nervous cells with electrical impulses in the future.

The future of the project is bright. While the team has so far established a means of producing pressure sensations with a prosthetic skin, they hope to introduce additional sensory inputs (human skin is capable of six distinct touch sensations) as the material develops further.

The eventual goal is to use the device to enable individuals with prosthetics to regain a sense of touch. If future developments are as successful as this one, that sense will include the ability to differentiate between hot and cold, silk and wool.

“We have a lot of work to take this from experimental to practical applications,” Bao said to Abate. “But after spending many years in this work, I now see a clear path where we can take our artificial skin.”