MECHANICAL ENGINEERING | FEBRUARY2016 | P.19
• Components as thin as .0005"
• Eliminates cost of hard tooling
• Eliminates burring and stress
• Short lead times
• Prototype through production
• In-house forming, laminating,
Photo Etched Parts
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Graphene sheets are today's “it” material, prized for mechanical strength as well as interesting
electrical properties. But on their own,
these single atom-thick sheets will curl up
or clump. And don’t even think about picking one up unless it’s mounted on a much
thicker backing or in a frame.
Now, researchers at the University of
Pennsylvania in Philadelphia have produced a plate of super-thin material that
can be picked up and held between two
fingers. These plates aren’t quite as thin
as graphene, but at 25 to 100 nm thick,
they are much thinner than a wavelength
The plates are made of aluminum oxide,
which is deposited one atomic layer at a
time to achieve precise control of thickness
and a distinctive honeycomb shape.
“Aluminum oxide is actually a ceramic,
so something that is ordinarily pretty
brittle,” said lead researcher Igor Bargatin,
an assistant professor at Penn’s School
of Engineering and Applied Science. “You
would expect it, from daily experience,
to crack very easily. But the plates bend,
twist, deform, and recover their shape in
such a way that you would think they are
made out of plastic. The first time we saw
it, I could hardly believe it.”
Indeed, instead of curling or clumping,
the corrugated plates spring back to their
original shape after being bent and twisted.
Also, when held firm on one end, the plates
remain rigid rather than sagging like a thin
sheet of plastic.
The plates are also less prone to sticking to the side of a surface due to Van der
Waals forces. The honeycomb structure
doesn’t provide for as many surface-to-surface contact points as a simple plane.
The material has intriguing potential for
aerospace and micro-mechanical applica-
tions, where strength and light weight are
“The wings of insects are a few microns
thick, and can’t be thinner because they’re
made of cells,” Bargatin said. “The thin-
nest man-made wing material I know of
is made by depositing a Mylar film on a
frame, and it’s about half a micron thick.
Our plates can be ten or more times thin-
ner than that, and don’t need a frame at all.
As a result, they weigh as little as a tenth of
a gram per square meter.”
The team published its findings in the
journal Nature Communications. ME
A NANOSCALE OBJECT
YOU CAN PICK UP
This nanometers-thick plate
of aluminum oxide is held
between two gloved fingers.