(February 29, 2016) EPFL
researchers have developed conductive tracks that can be bent and stretched up
to four times their original length. They could be used in artificial skin,
connected clothing and on-body sensors.
Conductive tracks are usually hard printed on a board. But
those recently developed at EPFL are altogether different: they are almost as
flexible as rubber and can be stretched up to four times their original length
and in all directions. And they can be stretched a million times without
cracking or interrupting their conductivity. The invention is described in an
article published today in the journal Advanced Materials.
Both solid and flexible, this new metallic and partially
liquid film offers a wide range of possible applications. It could be used to
make circuits that can be twisted and stretched – ideal for artificial skin on
prosthetics or robotic machines. It could also be integrated into fabric and
used in connected clothing. And because it follows the shape and movements of
the human body, it could be used for sensors designed to monitor particular
biological functions.
“We can come up with all sorts of uses, in forms that are
complex, moving or that change over time,” said Hadrien Michaud, a PhD student
at the Laboratory for Soft Bioelectronic Interfaces (LSBI) and one of the study
authors.
Extensive research has gone into developing an elastic
electronic circuit. It is a real challenge, as the components traditionally
used to make circuits are rigid. Applying liquid metal to a thin film in
polymer supports with elastic properties naturally seems like a promising
approach.
Thin and reliable
Owing to the high surface tension of some of these liquid
metals, experiments conducted so far have only produced relatively thick
structures. “Using the deposition and structuring methods that we developed,
it’s possible to make tracks that are very narrow – several hundredths of a
nanometer thick – and very reliable,” said Stéphanie Lacour, holder of the
Bertarelli Foundation Chair in Neuroprosthetic Technology and who runs the lab.