Stanford scientists reveal artificial skin device for prosthetics

Stanford University professor Zhenan Bao and her team created an artificial skin device that can send pressure sensations to brain cells.--Courtesy of Bao Lab

As researchers explore the benefits of artificial skin in prosthetics, scientists at Stanford University are developing a synthetic skin that can detect pressure and send signals to living brain cells, a big step forward in the field and a potential boon for the creation of wearable electronics and implantable devices.

A team of engineers led by Zhenan Bao, a professor of chemical engineering at Stanford, created a plastic, skinlike material that contains two layers. An elastic top layer consists of carbon nanotubes that can detect pressure and conduct electricity, while a bottom circuit layer uses inkjet technology from Xerox's ($XRX) PARC unit to translate the messages, much like Morse code. More pressure applied on the outer layer causes more frequent electrical impulses, while removing pressure stops the pulses, similar to real skin. An external battery powers the device, forgoing the need for wires.

But the team also had to prove that the artificial skin could communicate with the brain. Scientists created a line of neurons to simulate the human nervous system and translated electronic pressure signals from the synthetic skin into light pulses. The pulses activated the neurons, showing that the skin could generate a comparable neurological response. Scientists published their findings in a recent issue of 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," Bao said in a statement.

Next up, scientists plan to develop new technology that covers a wider range of sensations. There are 6 types of biological sensing mechanisms in the human hand, and the Stanford team's experiment covered just one. In the future, a flexible electronic covering could fold over a prosthetic hand, resulting in greater tactile capabilities for patients. "We have a lot of work to take this from experimental to practical applications. But after spending many years in this work, I now see a clear path where we can take our artificial skin," Bao said.

The recent findings build on Bao's previous work in the field. Last year, Bao and her team unveiled a tiny sensor that measures brain pressure in mice. The wireless device could also read one of the team member's pulses without touching him, a fruitful discovery as scientists search for alternative materials for prosthetics and wearable monitors.

Stanford scientists are not the only ones delving into neuroprosthetics. Neuroscientists at the University of Chicago recently found that artificial touch depends on several components of electrical stimuli such as the strength and frequency of signals. The research could have implications for prosthetics development as scientists look for better ways to create artificial sensations and stimulate the brain. The team published their study in a recent issue of the Proceedings of the National Academy of Sciences (PNAS).

- here's the Science abstract
- read the Stanford University statement
- here's the PNAS abstract
- read more about the University of Chicago study