NanofabricationThis section provides information on the history and modern developments in nanofabrication. |
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Bugs, which make magnetic crystals for the purpose of orientation in the Earth magnetic fields, have been discovered.
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A team of Rice University chemists lead by Eugene Zubarev have observed an unusual and potentially useful phenomenon: tiny particles, known as “gold nanorods” spontaneously assemble themselves into perfect rings (see picture with an image of a ring and a schematic drawing of a single nanorod in the center). The researches covered gold nanorods with a layer of a polymer, thus making them solvable in chloroform. As the chloroform solution, placed on a substrate, evaporates, its temperature reduces thus causing condensation of water from the air. These newly formed droplets of water act as templates for nanorods and organize them into circles.
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Eugene Zubarev and his collaborators at Rice University developed a new bioinspired approach to selfassembly of nanoscale constructs involving gold and silver nanoparticles. The method is based on the Nature most famous chemical innovations – the selfassembly of lipid membranes that surround every living cell.
The Figure illustrates the idea of this new principle of selfassembly.
E. R. Zubarev, J. Xu, A. Sayyad, J. D. Gibson "Amphiphilicity-Driven Organization of Nanoparticles into Discrete Assemblies." J. Am. Chem. Soc., 128 (2006): 15098-15099.
E. R. Zubarev, J. Xu, J. D. Gibson, A. Sayyad "From Small Building Blocks to Complex Molecular Architecture." Org. Lett., 8 (2006): 1367-1370.
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Michael Faraday, arguably, the greatest experimental physicists of all times, became famous for his works on electro-magnetisms. What is less known is that he made the first experiments with nanoparticles (gold colloids) and thus initiated the fields of nanoscience and nanotechnology.
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Highly-focused, high-energy electron beam can be used to etch holes and to modify nanowires in various ways. The picture shows a nanowires, about 15 nm in diameter, with two nanoholes, each being about 2.5 nm in diameter. Making such small holes in metallic wires constitutes a significant achievement in nanofabrication. The method was perfected by Mikas Remeika, while working in Bezryadin laboratory. The images are courtesy M. Remeika and A. Bezryadin (Physics/UIUC).
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Two electrodes (red) biased with a voltage produce an electric field around them with the maximum somewhere between the electrodes. This electric field polarizes nanoparticles and molecules which might be present near the electrodes and attracts them into the gap.
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Single molecules can serve as convenient templates or scaffolds for metal deposition.
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A buffer solution with 13 micron long double-stranded DNA is deposited over a Si substrate with a trench.
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The experiment is similar to the previous one.
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The figure shows an example of a suspended structure "sculptured" by a focused electron beam. The experiment is done using a Scanning Electron Microscope (SEM).
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(a) A scanning electron microscope (SEM) micrograph of a chain of graphitized carbon nanoparticles self-assembled between two Cr microelectrodes. The chain length is 1.2 microns. (b) An example of a longer chain. The image shows a part of a 6 micron long chain and one Pt electrode.
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