Buckling Carbon Nanotubes Show Promise for Stretchable Electronics

Led by the Rogers Research Group at the University of Illinois at Urbana-Champaign, a number of university research groups are pursuing the development of stretchable electronics for novel implantable medical devices and other applications. Adding to the exciting field is a team of researchers at North Carolina State University (NC State; Raleigh) that has exploited the sturdy, stable, and conductive properties of carbon nanotubes to create novel elastic conductors.

The key to stretchable electronics is developing elastic conductors that can reliably transmit electrical signals despite being stretched or elongated. To achieve these stretchy, effective conductors, the NC State team has discovered a method of "buckling" carbon nanotubes on the plane of a substrate.

Employing a transfer printing process, the researchers place aligned carbon nanotubes onto an elastic substrate. Next, the substrate is elongated. In turn, the carbon nanotubes are separated; however, they maintain their parallel alignment. When the substrate is released, the nanotubes buckle and create a pattern of parallel squiggly lines on a flat surface, according to the researchers. As a result of this process, the carbon nanotubes can be stretched and bent without compromising their electrical properties.

This nanotube-buckling process could allow for efficient, large-scale production of stretchable conductors, the researchers note. In addition, it is compatible with existing manufacturing operations. "For example, roll-to-roll printing techniques could be adapted to take advantage of our new method," says Yong Zhu, assistant professor of mechanical and aerospace engineering and lead author of a paper describing the buckling method.