Nanofabrication method paves way for new optical devices

October 05, 2007

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. "It's 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 demonstrates a new type of patterning technique that is cheap, but also one that can produce very high quality optical materials with interesting properties."

For example, if the perforations or holes are patterned into microscale "patches," they show dramatically different transmission behavior of light compared to an infinite array of holes. The patches appear to focus light while the infinite arrays do not.

Moreover, their optical transmission can be altered simply by changing the geometry of perforations rather than having to "cook" a new composition of materials. This feature makes them very attractive in terms of tuning their behavior to a given need with ease. These materials also can be superior as optical sensors, and they open the possibility of ultra-small sources of light. Furthermore, given their precise organization, they can serve as templates for making their own clones or for making other ordered structures at the nanoscale, such as arrays of nanoparticles.

"This work is exactly the kind of high-risk, high-potential transformative research NSF's Division of Materials Research is interested in supporting," said Harsh Deepak Chopra, program manager at the National Science Foundation (NSF), which funded the research. "The early results are extremely promising and suggest a whole new generation of optical devices."
-end-
In addition to Odom, other authors of the paper are Joel Henzie (lead author) and Min Hyung Lee, both graduate students in Odom's research group at Northwestern.

Northwestern University

Related Nanomaterials Articles from Brightsurf:

Spinal injuries: the recovery of motor skills thanks to nanomaterials
Re-establishing motor skills and neuronal connectivity thanks to the implantation of carbon nanotubes in the injury site.

Nanomaterials based strategies for treatment of hypoxic tumor
Hypoxic tumor microenvironment restricts efficiency of tumor therapies and leads to serious results of tumor recurrence and high mortality.

Trapping and controlling light at the interface of atomically thin nanomaterials
In a recent study, scientists at Cornell University propose a novel method by which nanoscale light can be manipulated and transported.

New way to check the quality of nanomaterials like graphene
A new way to check the quality of nanomaterials like graphene has emerged from a team at the University of Sussex.

Nanobiohybrids: A synergistic integration of bacteria and nanomaterials in cancer therapy
Nanobiohybrids: A Synergistic Integration of Bacteria and Nanomaterials in Cancer Therapy- BIO Integration.

Electronics for high-altitude use can get smaller and sturdier with new nanomaterials
Demand is growing for new materials that can be printed at ever smaller dimensions.

Water-free way to make MXenes could mean new uses for the promising nanomaterials
Ten years after producing the first sample of the now widely studied family of nanomaterials, called MXenes, Drexel University researchers have discovered a different way to make the atom-thin material that presents a number of new opportunities for using it.

Magnetic nanomaterials become an effective treatment against liver fibrosis
Fibrosis may affect different body organs. It develops as a reaction to long-time inflammation and is supposed to isolate the inflammation site from surrounding tissues.

More efficient risk assessment for nanomaterials
Nanotechnology is booming, but risk assessment for these tiny particles is a laborious process that presents significant challenges to the German Federal Institute for Risk Assessment (BfR).

New technology gives insight into how nanomaterials form and grow
A new form of electron microscopy allows researchers to examine nanoscale tubular materials while they are 'alive' and forming liquids -- a first in the field.

Read More: Nanomaterials News and Nanomaterials Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.