Stanford Researchers Build Transparent, Super-stretchy Skin-like Sensor

Imagine having skin so supple you could stretch it out to more than twice its normal length in any direction -- repeatedly -- yet it would always snap back completely wrinkle-free when you let go of it. You would certainly never need Botox. That enviable elasticity is one of several new features built into a new transparent skin-like pressure sensor that is the latest sensor developed by Stanford's Zhenan Bao, associate professor of chemical engineering, in her quest to create an artificial "super skin." The sensor uses a transparent film of single-walled carbon nanotubes that act as tiny springs, enabling the sensor to accurately measure the force on it, whether it's being pulled like taffy or squeezed like a sponge.

"This sensor can register pressure ranging from a firm pinch between your thumb and forefinger to twice the pressure exerted by an elephant standing on one foot," said Darren Lipomi, a postdoctoral researcher in Bao's lab, who is part of the research team.

"None of it causes any permanent deformation," he said.

Lipomi and Michael Vosgueritchian, graduate student in chemical engineering, and Benjamin Tee, graduate student in electrical engineering, are the lead authors of a paper describing the sensor published online Oct. 23 by Nature Nanotechnology. Bao is a coauthor of the paper.

The sensors could be used in making touch-sensitive prosthetic limbs or robots, for various medical applications such as pressure-sensitive bandages or in touch screens on computers.

The key element of the new sensor is the transparent film of carbon "nano-springs," which is created by spraying nanotubes in a liquid suspension onto a thin layer of silicone, which is then stretched.