EVANSTON, Ill. --- An innovative and inexpensive way of making nanomaterials on a large scale has resulted in novel forms of advanced materials that pave the way for exceptional and unexpected optical properties. The new fabrication technique, known as soft lithography, offers many significant advantages over existing techniques, including the ability to scale-up the manufacturing process to produce devices in large quantities.
The research, led by Northwestern University chemist Teri Odom, appears as the cover story in the September 2007 issue of the journal Nature Nanotechnology.
The optical nanomaterials in this research are called plasmonic metamaterials because their unique physical properties originate from shape and structure rather than material composition only. Two examples of metamaterials in the natural world are peacock feathers and butterfly wings. Their brightly colored patterns are due to structural variations at the hundreds of nanometers level, which cause them to absorb or reflect light.
Through the development of a new nanomanufacturing technique, Odom and her colleagues have succeeded in making gold films with virtually infinite arrays of circular perforations as small as 100 nanometers in diameter -- 500 to 1,000 times smaller than the diameter of a human hair. On a magnified scale, these perforated gold films look like Swiss cheese except the perforations are well-ordered and can spread over macroscale distances. The researchers ability to make these optical metamaterials inexpensively and on large wafers or sheets is what sets this work apart from other techniques.
One of the biggest problems with nanomaterials has always been their scalability, said Odom, associate professor of chemistry in the Weinberg College of Arts and Sciences. Its been very difficult or prohibitively expensive to pattern them over areas larger than about one square millimeter. This research is exciting not only because it demons
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