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Thin films of silicon nanoparticles roll into flexible nanotubes
June 15, 2005CHAMPAIGN, Ill. - By depositing nanoparticles onto a charged surface, researchers at the University of Illinois at Urbana-Champaign have crafted nanotubes from silicon that are flexible and nearly as soft as rubber.
"Resembling miniature scrolls, the nanotubes could prove useful as catalysts, guided laser cavities and nanorobots," said Sahraoui Chaieb, a professor of mechanical and industrial engineering at Illinois and a researcher at the Beckman Institute for Advanced Science and Technology.
To create their flexible nanotubes, Chaieb and his colleagues - physics professor Munir Nayfeh and graduate research assistant Adam Smith - start with a colloidal suspension of silicon nanoparticles (each particle is about 1 nanometer in diameter) in alcohol. By applying an electric field, the researchers drive the nanoparticles to the surface of a positively charged substrate, where they form a thin film.
Upon drying, the film spontaneously detaches from the substrate and rolls into a nanotube. Nanotubes with diameters ranging from 2 to 5 microns and up to 100 microns long have been achieved.
Using an atomic force microscope, the researchers found that the Young's modulus (a measure of a material's elasticity) of the film was about 5,000 times smaller than that of bulk silicon, but just 30 times larger than that of rubber.
"We suspect that the nanotubes consist of silicon nanoparticles held together by oxygen atoms to form a three-dimensional network," Chaieb said. "The nanotubes are soft and flexible because of the presence of the oxygen atoms. This simple bottom-up approach will give other researchers ideas how to build inexpensive active structures for lab-on-chip applications."
"Because the silicon nanoparticles - which are made using a basic electrochemical procedure - have properties such as photoluminescence, photostability and stimulated emission, the resulting nanotubes might serve as nanodiodes and flexible lasers that could be controlled with an electric field," Nayfeh said.
University of Illinois at Urbana-Champaign
Upon drying, the film spontaneously detaches from the substrate and rolls into a nanotube. Nanotubes with diameters ranging from 2 to 5 microns and up to 100 microns long have been achieved.
Using an atomic force microscope, the researchers found that the Young's modulus (a measure of a material's elasticity) of the film was about 5,000 times smaller than that of bulk silicon, but just 30 times larger than that of rubber.
"We suspect that the nanotubes consist of silicon nanoparticles held together by oxygen atoms to form a three-dimensional network," Chaieb said. "The nanotubes are soft and flexible because of the presence of the oxygen atoms. This simple bottom-up approach will give other researchers ideas how to build inexpensive active structures for lab-on-chip applications."
"Because the silicon nanoparticles - which are made using a basic electrochemical procedure - have properties such as photoluminescence, photostability and stimulated emission, the resulting nanotubes might serve as nanodiodes and flexible lasers that could be controlled with an electric field," Nayfeh said.
University of Illinois at Urbana-Champaign
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Golden Scales: Nanoscale Mass Sensor from Berkeley Can Be Used to Weigh Individual Atoms and Molecules
There's a new "gold standard" in the sensitivity of weighing scales. Using the same technology with which they created the world's first fully functional nanotube radio, researchers with Berkeley Lab and the University of California (UC) at Berkeley have fashioned a nanoelectromechanical system (NEMS) that can function as a scale sensitive enough to measure the mass of a single atom of gold.
'Nanonet' circuits closer to making flexible electronics reality
Researchers have overcome a major obstacle in producing transistors from networks of carbon nanotubes, a technology that could make it possible to print circuits on plastic sheets for applications including flexible displays and an electronic skin to cover an entire aircraft to monitor crack formation.
Researchers generate hydrogen without the carbon footprint
A greener, less expensive method to produce hydrogen for fuel may eventually be possible with the help of water, solar energy and nanotube diodes that use the entire spectrum of the sun's energy, according to Penn State researchers.
LLNL researchers peer into water in carbon nanotubes
Researchers have identified a signature for water inside single-walled carbon nanotubes, helping them understand how water is structured and how it moves within these tiny channels.
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