Tech Briefs Magazine - August 2021 - 24

Electrical/Electronics
Heat-Resilient Silver Circuits for Extreme Electronics
The tough circuits could withstand the grueling demands of energy production, space
exploration, and more.
Michigan State University, East Lansing
team of researchers has developed
heat-resilient silver circuitry for de -
vices such as next-generation fuel cells,
high-temperature semiconductors, and
solid oxide electrolysis cells for the automobile,
energy, and aerospace in dustries.
For example, NASA developed a solid
oxide electrolysis cell that enabled the
Mars 2020 Perseverance rover to make
oxygen from gas in the Martian atmosphere.
To help such prototypes become
commercial products, though, they'll
need to maintain their performance at
high temperatures over long periods of
time.
A
Solid oxide fuel cells work like solid
oxide electrolysis cells in reverse. Rather
than using energy to create gases or
fuel, they create energy from those
chemicals. The researchers are able to
electrochemically react those gases to
get electricity out and the process is
more efficient than exploding fuel like
an internal combustion engine.
Even without explosions, the fuel cell
needs to withstand intense working conditions.
The devices commonly operate
at about 700 to 800 °C for 40,000 hours
over their lifetime. That's approximately
1,300 to 1,400 °F or about double the
The process to create more resilient circuitry is
demonstrated by creating a silver Spartan helmet.
(Credit: Acta Materialia Inc./Elsevier)
temperature of a commercial pizza
oven. Over that lifetime, they are thermally
cycling - cooling down and heating
back up - during which circuit
leads could pop off.
Thus, one of the hurdles facing this
advanced technology is rather rudimentary:
The conductive circuitry, often
made from silver, needs to stick better
to the underlying ceramic components.
The secret to improving the adhesion
was to add an intermediate layer of
porous nickel between the silver and
the ceramic.
By performing experiments and computer
simulations of how the materials
interact, the team optimized how it de -
posited the nickel on the ceramic. And
to create the thin, porous nickel layers
on the ceramic in a pattern or design of
their choosing, the researchers turned
to screen printing of the electronics.
Once the nickel is in place, the team
puts it in contact with silver that's melted
at a temperature of about 1,000 °C.
The nickel not only withstands that heat
- its melting point is 1,455 °C - but it
also distributes the liquified silver uniformly
over its fine features using what's
called capillary action.
When the silver cools and solidifies,
the nickel keeps it locked onto the ce -
ramic, even in the 700 to 800 °C heat it
would face inside a solid oxide fuel cell
or a solid oxide electrolysis cell. This
approach also has the potential to help
other technologies where electronics
can run hot.
For more information, contact Jason
Nich olas, Associate Professor, at jdn@msu.edu.
Graphene " Nano-Origami " Creates Tiny Microchips
The microchips are about 100 times smaller than conventional microchips.
University of Sussex, Brighton, United Kingdom
iny microchips can be made from
graphene and other two-dimensional
(2D) materials using a form of " nanoorigami. "
By creating kinks in the structure
of graphene, researchers made the
nanomaterial behave like a transistor
and showed that when a strip of
graphene is crinkled in this way, it can
behave like a microchip that is around
100 times smaller than conventional
microchips.
Using these nanomaterials could
make computer chips smaller and faster.
This kind of technology (straintronics)
- using nanomaterials as opposed to
electronics - allows space for more
chips inside any device.
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Cov
T
Instead of adding foreign materials
into a device, the researchers created
structures from graphene and other 2D
materials simply by adding deliberate
kinks into the structure. By making this
sort of corrugation, they can create a
smart electronic component like a transistor
or a logic gate.
The development is a greener, more
sustainable technology. Because no additional
materials need to be added and the
process works at room temperature rather
than high temperature, it uses less energy
to create.
For more information, contact Neil Vowles
at N.G.Vowles@sussex.ac.uk; (+44) 01273
873712.
www.techbriefs.com
ToC
The base of the 2D material. The white lines
show the structural kinks that modify the electrical
properties mechanically.
Tech Briefs, August 2021
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Tech Briefs Magazine - August 2021

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