Using carbon nanotubes bent to act like springs, Stanford researchers have developed a stretchable, transparent skin-like sensor that can be stretched to more than twice its original length and bounce back perfectly to its original shape. It can sense pressure from a firm pinch to thousands of pounds. Potential applications include prosthetic limbs, robotics, and touch-sensitive computer displays.
A 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. When the nanotubes are airbrushed onto the silicone, they tend to land in randomly oriented clumps. When the silicone is stretched, some of the “nano-bundles” get pulled into alignment in the direction of the stretching. When the silicone is released, it rebounds back to its original dimensions, but the nanotubes buckle and form little nanostructures that look like springs.
The sensors could be used in making touch-sensitive prosthetic limbs or robots, for various medical applications such as pressure-sensitive bandages or in touchscreens on computers.