Ann Arbor, Michigan - Researchers at the University of Michigan have discovered that polyurethane studded with gold nanoparticles can conduct electricity even when stretched more than twice its original length.
Flexible electronics have a wide variety of possibilities, from bendable displays and batteries to medical implants that move with the body, UMich said in a 17 July news release.
"Essentially the new nanoparticle materials behave as elastic metals," said Nicholas Kotov, Professor of Engineering at UMich. "It's just the start of a new family of materials that can be made from a large variety of nanoparticles for a wide range of applications."
The researchers said finding good conductors that still work when pulled to twice their length is a difficult task. The team was surprised that spherical gold nanoparticles embedded in polyurethane could outcompete the best of these in stretchability and concentration of electrons.
The team took electron microscope images of the materials at various tensions. They found that the nanoparticles start out dispersed, but under strain they could filter through minuscule gaps in the PU, connecting in chains, as they would in a solution.
"As we stretch, they rearrange themselves to maintain the conductivity, and this is the reason why we got the amazing combination of stretchability and electrical conductivity," Kotov said.
Kotov sees the stretchable conductors as electrodes, for use in applications such as brain implants. Rigid electrodes create scar tissue that prevents the electrode from working over time, he said, but electrodes that move like brain tissue could avoid damaging cells.
