Researchers Explore Possibilities On The Nanoscale
Vanderbilt researchers working at the smallest scale celebrate a huge milestone this year. The Vanderbilt Institute of Nanoscale Science and Engineering (VINSE), seeded from a university-funded $16 million venture capital fund initiative, celebrates its 10th anniversary in December.
There is much to celebrate, including the fact that in the past decade, VINSE has attracted more than $75 million in federal funding for nanoscience research, says VINSE Director Sandra J. Rosenthal.
An interdisciplinary institute devoted to the science and engineering of matter on the atomic scale, VINSE proves that even the smallest matter matters. Through nanotechnology, researchers make extremely small materials—far smaller than the width of a human hair—but with enhanced capabilities relevant to everything from energy use to the efficient delivery of medications.
“The fundamental thing that makes nanoscience interesting is that when you fabricate a material on the nanoscale, new properties are discovered all the time. These new properties open up a myriad of possibilities for potential applications,” says Rosenthal, the Jack and Pamela Egan Chair of Chemistry and professor of chemical and biomolecular engineering, chemistry, physics and pharmacology. “We study those possibilities and figure out what applications you can use for those properties.”
With partners that include Oak Ridge National Laboratory and Fisk University, VINSE fosters cutting-edge research in biology and medicine, optics, carbon-based nanostructures and sensors, as well as a new emphasis at the interface of nanoscience and energy. Roughly a quarter of Vanderbilt’s engineering faculty are part of VINSE, comprising nearly half of the institute’s researchers.
In recent months, the institute earned a $5 million stake in a $20 million National Science Foundation grant to strengthen research development infrastructure in Tennessee. A smaller but critically important $569,000 grant from NSF’s American Recovery and Reinvestment Act allowed for the renovation of air-handling equipment in the VINSE clean room and an upgrade of the toxic gas monitoring system.
Power of Research
The core facilities of VINSE, created and equipped with $5 million of the initial investment from the university’s endowment, provide highly specialized instrumentation. “The fact that we have this kind of fabrication and characterization available has allowed us to land some outstanding individuals who are nanoscience researchers,” Rosenthal says.
Among the latest recruits is Assistant Professor of Mechanical Engineering Jason Valentine, an expert on cloaking—hiding objects from view by bending light around them.
While cloaking evokes images from the world of Harry Potter or Star Trek, its more practical applications include the possible creation of ever smaller, lighter and more efficient optical systems and materials for telecommunications and computing.
As a graduate student at University of California–Berkeley, Valentine was part of a research team that created a cloaking technique dubbed a “carpet cloak” made from a silicon sheet and drilled with precisely placed holes. The cloak alters the refraction of light as it passes through the material—thinner than a human hair—making an object appear flat.
“What we are doing is virtually ripping a hole in space,” Valentine says, albeit a very tiny hole. Since naturally occurring materials do not have this kind of flexibility in their optical properties, Valentine and the Berkeley research team used metamaterials—artificial materials engineered with nanoscale machining methods—to achieve material structuring much smaller than the wavelength of light.
While the effect was achieved on the two-dimensional scale, Valentine is continuing the next step at Vanderbilt—working toward the fabrication of such materials on a larger scale and in 3-D. These developments could prove useful in manipulating light in silicon chips, the foundation of modern electronics, to enable more efficient and flexible light-routing architectures.
“Cloaking is a great demonstration of the technology and a great way to pull young students into the science field,” Valentine says of the public interest in cloaking. “Normally, they wouldn’t be aware of scientific breakthroughs.”
Saving Energy, Saving Lives
While Valentine works to manipulate light, Rosenthal’s lab experienced a breakthrough by producing a new nanomaterial that for the first time emits a white light. Rosenthal aims to make the material bright and white enough to become commercially viable.
“A lot of people said this (discovery of white light on the nanoscale) would never happen. Nobody predicted it,” she says.
Rosenthal’s lab uses specialized instrumentation to synthesize semiconducting nanocrystals, also called quantum dots. A building block of nanotechnology, quantum dots are just a few millionths of a millimeter across, exhibiting unique electronic, optical and magnetic properties that can be utilized in a variety of technologies.
Among other projects, Rosenthal also is investigating ways to bind drugs to a cell’s protein, providing a nanocrystal beacon to track the movement of proteins that control serotonin through the brain. This could be a potential breakthrough in mental health, as an imbalance of serotonin is associated with many major mental illnesses.
“My research is a lot of fun,” Rosenthal says. “One day I’m saving the planet trying to develop energy-efficient lighting. Another day I’m trying to do fundamental research that may one day help alleviate the suffering of people with mental illness, and it’s nanotechnology that’s enabling all of it.”
Assistant Professor of Electrical Engineering Sharon Weiss investigates nanotechnology that could potentially help a drug cocktail hone in on hard-to-reach tumors in cancer patients, among other potential applications.
Weiss works with porous silicon crystals. Sponge-like material filled with billions of tiny holes, the crystals can be manipulated through an etching process that allows scientists to load the tiny holes with other substances.
Weiss pairs with Paul Laibinis, professor of chemical and biomolecular engineering, in research that involves synthesizing DNA molecules inside the pores with certain drugs to create a highly selective sensor. By evaluating how light interacts with the porous silicon, it is possible to detect the presence of trace amounts of biological material. This can aid in a number of processes, including the delivery of medicines to very specific areas in the body, Weiss explains.
Peter Cummings, the John R. Hall Professor of Chemical Engineering, has been instrumental in shaping the government’s National Nanotechnology Initiative Strategy. He recently participated in a strategic directions workshop to provide input into the government’s blueprint for nanoscience research for the next decade. (For details, see www.nano.gov).
The science of small has quietly revolutionized many aspects of technology and that revolution is continuing, Cummings says.
He notes that researchers at Vanderbilt and elsewhere are making strides in molecular electronics, with the goal of constructing devices with a switch comprised of just one molecule.
This would represent the ultimate miniaturization of electronics. “People are contemplating what’s going to happen beyond silicon,” he says of the material that forms the basis of modern computer chips. In fact, Vanderbilt’s Weiss, who has a secondary appointment as assistant professor of physics, is working with Richard Haglund, professor of physics, on methods to speed computing processes by using light rather than metal to quickly transfer information. (See Vanderbilt Engineering, fall 2010.)
Cummings says that Vanderbilt engineers are using high-performance computing-based techniques, including the use of GPUs (graphical processing units, primarily developed for video games) to research other aspects of nanoscience, including study of nanoconfined fluids, which are important for lubrication of moving parts in nanoscale devices.
Vanderbilt has a grant, led by Associate Professor of Mechanical Engineering Greg Walker, to build a fast GPU cluster for scientific computation, and Oak Ridge National Laboratory, where Cummings is Principal Scientist in the Center for Nanophase Materials Science, is building a huge GPU cluster in collaboration with Georgia Tech.
Matter even smaller than that of the nanoscale—at the “femto” and “atto” scale—already is under exploration as well. Tools such as atomic force microscopes allow scientists to measure and watch individual chemical reactions take place, moving far beyond the theoretical stage. Cummings says it was just a short time ago that scientists could barely imagine the innovations happening today in nanoscience. “What was inconceivable a couple of decades ago is a reality today,” he says.
Source: Vanderbilt University /...
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