LOS ANGELES, Dec. 19, 2008 -- The University of Southern California (USC) has opened a nanoimaging center for scientists and engineers probing the mysteries of nanoscale materials and systems.
The center, which was unveiled Dec. 11 at a special symposium, houses three new scanning electron microscopes (SEMs). The instruments will allow researchers from a broad range of the biological and life sciences to gain a better understanding of nanomaterials using the latest, most sophisticated 3-D imaging technology available.
Creation of the new center, a core lab operated jointly by the Viterbi School and the college, is located in the engineering school’s Center for Electron Microscopy and Microanalysis.
Chemical engineering and materials science professor Steven R. Nutt, who directs the Viterbi School’s M.C. Gill Foundation Composites Center, believes the new instruments will transform the microscope from a device for static observations to an instrument for bold and vigorous experimentation.
“These new imaging instruments will support multidisciplinary research in biomedical nanoscience, which could lead to discoveries in the early detection and more effective treatment of disease, as well as the development of prosthetic devices that restore function to tissue and organs," Nutt said. “They will allow us to pursue 3-D nanoimaging, nanomachining and nanomanipulation in a big way.”
The new instruments, considered state-of-the-art for nanoscience imaging and fabrication, were procured with funds from the provost’s strategic Biomedical Nanoscience Initiative, in cooperation with JEOL (Japan Electron Optics Laboratory), and will be available to all USC faculty and students.
The new SEMs, which have different capabilities, utilize an electron beam to scan the surface of a sample, be it biological or inorganic, Nutt explained. The beam generates a signal that is detected and mapped to a viewing screen, where an image is created and can be magnified up to several hundred thousand times. Researchers can achieve high resolution on the order of a few nanometers.
“One of the most exciting capabilities we will have is something called a FIB, or focused ion beam,” he said. “Essentially, the SEM is combined with a second machine, the FIB, and both beams are focused on the sample. The electron beam will image the sample, but the FIB can be used to cut or machine the sample while imaging it with the electron beam. This enables the user to machine the sample while watching the process at high magnification.”
Three basic tasks can be performed with FIB capabilities, Nutt said. The first is progressive sectioning, using the ion beam to cut sequential slices of the sample, like slicing ultrathin lunch meat. The user can slice, image, slice, image, and so on and so on, progressively revealing the internal structure of the sample. Saving the sequence of images also lets the researcher reconstruct a 3D image of the internal structure, a process called “3D reconstruction,” which is a powerful visualization tool.
Researchers can also perform site-specific TEM (transmission electron microscope) sample preparation. This process utilizes a second type of electron microscope, the TEM, and requires preparation of ultrathin sections of a sample that are electron transparent, Nutt said.
“The TEM sample prep is tedious and skill-intensive when performed by grinding and polishing, but the FIB can be used to prepare the thin sections in the SEM,” he said. “This is particularly valuable because the researcher will now be able to prepare a thin section from a specific region of interest, something that was extremely difficult to do by conventional means.”
The third task is machining and deposition. A researcher can sculpt and machine nanoscale and microscale devices and structures, perform ion-beam lithography, and build supersmall configurations that were previously very difficult or impossible to build.
"We expect these machines will be widely used in the physical sciences, life sciences and the engineering community,” Nutt said. “For example, they can be used to analyze nanostructures for electronic and photovoltaic devices, as well as for structural applications.”
As the design and fabrication of devices shrinks to the nanoscale, scientists desperately need the ability to see what they have created, Nutt emphasized. However, he views these machines as much more than just microscopes; he sees them as platforms for dynamic experiments, in which researchers can observe changes as they occur.
The researchers will also be able to modify and build structures in situ, like carbon nanotubes or modified viruses to deliver antibodies to specific cells, while simultaneously observing the structures at high resolution.
“This opens the door to a new kind of science in which we will be able to observe nano-scale phenomena with unprecedented detail," Nutt said.
For more information, visit: http://viterbi.usc.edu
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