Scientists have demonstrated that a new 'soft lithography' technique can be
used to manufacture complex nano-materials inexpensively on an industrial scale.
Research led by
Northwestern
University chemist Teri Odom has resulted in novel forms of advanced
materials with "exceptional and unexpected" optical properties.
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The new 'plasmonic metamaterials' are unique in that their physical
properties originate from shape and structure rather than just material
composition.
Two examples of meta-materials in the natural world are peacock feathers and
butterfly wings.
Their brightly coloured patterns are due to structural variations at the
level of just hundreds of nanometres which cause them to absorb or reflect
light.
The new nano-manufacturing technique has allowed Odom and her colleagues to
make gold film with virtually infinite arrays of circular perforations as small
as 100 nanometres in diameter, or 500 to 1,000 times thinner than a human hair.
On a magnified scale, the perforated gold film looks like Swiss cheese except
that the perforations are well ordered and can spread over macroscale distances.
The researchers' ability to make these optical meta-materials inexpensively
and on large wafers or sheets is what sets this work apart from other
techniques.
"One of the biggest problems with nano-materials has always been their
scalability," said Odom, who is associate professor of chemistry in the
Weinberg
College of Arts and Sciences.
"It has been very difficult or prohibitively expensive to pattern them over
areas larger than about one square millimetre.
"This research is exciting because it demonstrates a new type of patterning
technique that is cheap, but can also produce very high quality optical
materials with interesting properties."
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