Wednesday, December 2, 2015

TECH SPECIAL ..............Self-healing gel to boost foldable electronics


Self-healing gel to boost
 foldable electronics


Researchers in the Cockrell School of Engineering at The
University of Texas, Austin have devel oped a first-of-its-kind
 self-healing gel that repairs and connects electronic circuits,
 creating opportunities for the development of flexible
electronics, biosensors and batteries as energy storage
devices.
Although technology is moving toward lighter, flexible,
foldable and rollable electronics, the existing circuits that
 power them are not built to flex freely and repeatedly
self-repair cracks or breaks that can happen from normal
wear and tear.
Until now, self-healing materials have relied on application
 of external stimuli like light or heat.
The UT Austin “supergel“ material has high conductivity ­
the degree to which a material conducts electricity ­ and
strong mechanical and electrical selfhealing properties.
“In the last decade, the self-healing concept has been
popularised by people working on different applications,
but this is the first time it has been done without external
 stimuli,“ said mechanical engineering assistant professor
Yu.
“There's no need for heat or light to fix the crack or break
 in a circuit or battery, which is often required by previously
 developed self-healing materials.“
Yu and his team created the self-healing gel by combining
 two gels: a self-assembling metal-ligand gel that provides
 self-healing properties and a polymer hydrogel that is a
conductor.
A paper on the synthesis of their hydrogel appears in the
November issue of Nano Letters.
In this latest paper, the researchers describe how they
used a disc-shaped liquid crystal molecule to enhance the
 conductivity, biocompatibility and permeability of their
 polymer hydrogel.
They were able to achieve about ten times the conductivity
 of other polymer hydrogels used in bioelectronics and
conventional rechargeable batteries.
The nanostructures that make up the gel are the smallest
 structures capable of providing efficient charge and
energy transport.
The second ingredient of the self-healing hybrid gel is a
metal-ligand supramolecular gel. Using terpyridine
molecules to create the framework and zinc atoms as
a structural glue, the molecules form structures that
are able to self-assemble, giving it the ability to automatically
 heal after a break.
When the supramolecular gel is introduced into the polymer
 hydrogel, forming the hybrid gel, its mechanical strength
and elasticity are enhanced.
To construct the self-healing electronic circuit, Yu believes
 the self-healing gel would not replace the typical metal
conductors that transport electricity, but it could be used
 to join for other parts of the circuit.
“This gel can be applied at the circuit's junction points
 because that's often where you see the breakage,“
he said. “One day, you could glue or paste the gel to
 these junctions so that the circuits could be more
 robust and harder to break.“

AGENCIES




MM27NOV15

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