Nanofabrication method paves way for new optical devicesOctober 08, 2007EVANSTON, 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." Northwestern University |
|||||||||||||||||||||
| Related Nanomaterial Current Events and Nanomaterial News Articles Engineers explore environmental concerns of nanotechnology As researchers around the world hasten to employ nanotechnology to improve production methods for applications that range from manufacturing materials to creating new pharmaceutical drugs, a separate but equally compelling challenge exists. Growing cartilage -- no easy task Northwestern University researchers are the first to design a bioactive nanomaterial that promotes the growth of new cartilage in vivo and without the use of expensive growth factors. Minimally invasive, the therapy activates the bone marrow stem cells and produces natural cartilage. No conventional therapy can do this. Game-changing nanodiamond discovery for MRI A Northwestern University study shows that coupling a magnetic resonance imaging (MRI) contrast agent to a nanodiamond results in dramatically enhanced signal intensity and thus vivid image contrast. Researchers Develop "Nano Cocktail" to Target and Kill Tumors A team of researchers in California and Massachusetts has developed a "cocktail" of different nanometer-sized particles that work in concert within the bloodstream to locate, adhere to and kill cancerous tumors. NC State Develops Material That Could Boost Data Storage, Save Energy North Carolina State University engineers have created a new material that would allow a fingernail-size computer chip to store the equivalent of 20 high-definition DVDs or 250 million pages of text, far exceeding the storage capacities of today's computer memory systems. New insights into health and environmental effects of carbon nanoparticles A new study raises the possibility that flies and other insects that encounter nanomaterial "hot spots," or spills, near manufacturing facilities in the future could pick up and transport nanoparticles on their bodies, transferring the particles to other flies or habitats in the environment. Nanotech particles affect brain development in mice Maternal exposure to nanoparticles of titanium dioxide (TiO2) affects the expression of genes related to the central nervous system in developing mice. Remote-control closed system invented for inserting radio-active atoms inside fullerenes Virginia Tech chemistry Professor Harry C. Dorn, Emory and Henry College chemistry Professor James Duchamp, and Panos Fatouros, professor and chair of the Division of Radiation Physics and Biology at the Virginia Commonwealth University School of Medicine have co-invented a hands-off process for filling fullerenes with radio-active material. Research explores interactions between nanomaterials, biological systems The recent explosion in the development of nanomaterials with enhanced performance characteristics for use in commercial and medical applications has increased the likelihood of people coming into direct contact with these materials. Scientists advance safety of nanotechnology Scientists have identified for the first time a mechanism by which nanoparticles cause lung damage and have demonstrated that it can be combated by blocking the process involved, taking a step toward addressing the growing concerns over the safety of nanotechnology. More Nanomaterial Current Events and Nanomaterial News Articles |
|||||||||||||||||||||
|
|||||||||||||||||||||
|
|||||||||||||||||||||