Stretchy Gold Electronics Could Someday Live Inside Your Brain
What looks like a shiny piece of gold foil is actually a new stretchy conductive material that could one day be fashioned into electrode implants for the brain or pacemakers for the heart. Crafted from gold nanoparticles and an elastic polymer, the material retains its conductivity even when stretched to four times its original length.
“It looks like elastic gold,” said Nicholas Kotov, a chemical engineer at the University of Michigan. “But we can stretch it just like a rubber band.” When it stretches, it retains all the properties of a metal, including the ability to transport electrons.
Normally, stretching a circuit disrupts the interatomic connections that keep electrons flowing from one end to the other. Most existing stretchable electronics overcome this difficulty by using accordion- or spring-like folding wires that can expand and contract. But in the new material, no folds or convolutions are needed.
Its secret? Self-organizing gold nanoparticles that have been embedded into an elastic polymer, polyurethane.
When the shiny material is stretched, the nanoparticles self-organize into conductive chains, scurrying to fill the gaps in the elongating material. It’s the first material that relies on nanospheres to achieve intrinsic stretchable conductivity, Kotov and his colleagues report today in Nature.
Looking at the substance under electron microscopes revealed that the spheres snapped into chains under pressure, producing structures electrons could flow through. “And when you release the stress, they pretty much come back to their original position,” Kotov said.
The process is repeatable. And although conductance at maximal stretch is decreased to less than 10 percent of the original, it’s still enough to provide power to some devices, the team reports. (via Stretchy Gold Electronics Could Someday Live Inside Your Brain - Wired Science)