Gold Is The Secret Ingredient For Stretchy Conductors
by Masha Vodyanik, age 16
at the University of Michigan recently engineered an important
conductor made of gold nanoparticles and an elastic polymer. But what
looks like a shiny piece of gold foil and stretches like a rubber band
could potentially be made into electrode implants for the brain or the
When used as implants in the brain, conductive material
like this one have the potential to treat conditions like movement
disorders. In the heart, they could regulate cardiac activity. The
material could be designed to bend, mold and stretch according to the
human body, sticking over skin like temporary tattoos or rewiring
circuits inside the body itself.
Unlike in other circuits, this
stretchy plastic material retains its electric conductivity when
stretched to four times its original length. Other stretchable circuits
use accordion or spring-like folding wires that expand or contract so
stretching will not disturb the flow of electrons through the circuit.
With the new gold material, however, folds aren’t necessary because it
retains all of its metallic properties when stretched. When fully
stretched, conductivity is decreased by over 90 percent but it is still
enough to provide conductivity to some devices.
The secret is
self-organizing gold nanoparticles that are embedded into an elastic
polymer. When the material is stretched, these tiny gold spheres
organize themselves into conductive chains that fill gaps in the
elongated material. Under pressure, electrons flow through these gold
nanosphere ropes and the circuit runs uninterrupted. When stress is
relieved, nanospheres go back to their original positions.
there are on-going tests with prototype implants on rat brains. Teams
are also testing whether other nanoparticles besides gold can be used to
create stretchy conductors.
“The results suggest some very
interesting, unexpected effects of nanoparticle-elastomer composites,”
said John Rodgers, a scientist at the University of Illinois.
Scientists’ current goal is to move from a stretchy conductor to a
functioning electronic system that serves a purpose in the heart or the