Anchored by the university’s new state-of-the-art nanotech fabrication lab – or “clean” room – BC nanotechnology projects have made gains in solar energy collection, thermo electrics, high-efficiency batteries, biosensors able to detect the presence of disease and “metamaterials” capable of bending light beyond previously defined limits.
What exactly is the nanoscale? It is somewhere between the size of an atom and a bulk solid. Carbon nanotubes and wires, as well as patterns and features, are typically built or etched onto the surface of wafer-like chips, called substrates. It is upon these nanoscopic stages that the devices are producing results that were previously the subject of theorists.
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“A large fraction of the technologically relevant science taking place now and well into the future is being done at the nanoscale,” Prof. and Physics Department Chairman Michael Naughton said. “The activities of integrated science, which we embrace here at BC, are now revolving around the nanoscale… This is where science has led us up to this point.”
Naughton and his colleagues developed a nano-scale solar cell, inspired by the coaxial cable, that resolves the "thick & thin" dilemma of solar energy collection – producing technology thick or tall enough to capture solar rays, yet thin enough to allow efficient extraction of current. Naughton, and fellow professors Zhifeng Ren and Krzysztof Kempa have shown the nanocoax is more efficient than previously designed nanotech thin film solar cells.
"Many groups around the world are working on nanowire-type solar cells, most using crystalline semiconductors," said Naughton. "This nanocoax cell architecture, on the other hand, does not require crystalline materials, and therefore offers promise for lower-cost solar power with ultrathin absorbers. With continued optimization, efficiencies beyond anything achieved in conventional planar architectures may be possible, while using smaller quantities of less costly material."
Assistant Professor of Chemistry Dunwei Wang developed a tiny scaffold-like titanium structure of Nanonets coated with silicon particles. This anode material could pave the way for faster, lighter and longer-lasting Lithium-ion batteries, according to Wang.
"As researchers pursue the next generation of re-chargeable Lithium-ion battery technology, a premium has been placed on increased power and a greater battery life span," said Wang. "In that context, the Nanonet device makes a giant leap toward those two goals and gives us a superior anode material."
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Associate Professor of Physics Willie Padilla works with “metamaterials” – materials engineered to give them properties that exceed their natural limits. The Padilla lab developed a material capable of delivering a complex set of instructions to a beam of light and guiding electromagnetic waves around objects such as the corner of a building or the profile of the eastern seaboard. As directed by Padilla’s novel device, these beams continue to behave as if traveling in a straight line. In one computer simulation, Padilla found the device could steer a beam of light along the boundary of the US, stretching from Michigan to Maine, down the seaboard, around Florida and into the Louisiana bayou.
Padilla’s lab accomplished their feat by developing a much more precise set of instructions, which create a grid-like roadmap capable of twisting and turning a beam of light around objects or space. Their discovery is an extension of earlier metamaterial “cloaking” techniques, which have conjured up images of the Harry Potter character disappearing beneath his invisibility cloak.
Biology Professor Thomas Chiles and Research Associate Professor of Biology Dong Cai are probing the usefulness of nano-structures in health care. The Chiles lab developed a nano-scale biosensor capable of detecting certain proteins, including one present in human papillomaviris. By coating a cluster of nanotubes with a thin layer of protein-recognizing polymer, the sensor uses electrochemical signals to detect minute amounts of proteins, which could provide a crucial new diagnostic tool for the detection of a range of illnesses.
Cai said that studying the behavior of cells or activities, such as the movement of a sodium ion across the pores of a protein, requires tools and technology that can function at the molecular level of these biological properties. “Nanotechnology can be used to design diagnostic systems that not only define early stage changes or progression to a disease state, but also allow the identification of unique biological molecules, chemicals and structures not addressable by current tests,” he said. “They also offer new opportunities in the treatment and management of diseases and traumatic injuries.
The clean room lab, which opened in 2007, gives a home field advantage to BC researchers – providing ready access to state-of-the-art equipment, as well as eliminating the costs and time required to use facilities at other universities. The clean room gets its name from its dust-free environment. At the nanoscale, a dust particle can fall like a boulder into a creek bed, adhering to the surface of a substrate and wreaking havoc on their tiny features. A substrate can take four to six weeks to create and can be rendered useless if polluted.
An increasing number of projects have drawn together integrated teams from across the disciplines of biology, chemistry and physics. The focus on nanotechnology has also spread to the classroom. Last year, researchers offered a new seminar on nanotechnology, marking the first integrated sciences course offered at the university. Each week, professors lectured to a capacity crowd of slightly more than 40 graduate and upper-level undergraduate students.
Department chairs involved in the development of the course said it is the result of a sustained investment in faculty and facilities over the past decade that has both refined the expertise within the departments and moved them all closer to a model of integrated research and teaching.
“We couldn’t offer this course three years ago because we didn’t have integrated sciences – we didn’t have faculty whose work was truly meshed together,” said Chiles. “Now these visions are coming together and it’s pretty exciting.”
Source: Boston College news release