The detector which is interconnected based on the carbon atoms in graphene can sense light over an unusually broad range of wavelengths including terahertz waves between infrared
and body scanners used in airport security. he research is published in Nature Nanotechnology. Current technological applications for terahertz detection are limited as they need to be kept extremely cold to maintain sensitivity.
#An assembly line 3x thinner than a human hair Original Studyposted by Peter Ruegg-ETH Zurich on September 2 2014 Researchers have realized a long-held dream of building a nanoscale ssembly line.?
and DNA the assembly of nanotechnological components or small organic polymers or the chemical alteration of carbon nanotubes. e need to continue to optimize the system
The metallic nanostructures use surface plasmons waves of electrons that flow like a fluid across metal surfaces.
This shows that through nanoscale engineering of materials we can really make a difference in how we make fuels
#Test keeps graphene pure enough for electronics Rice university rightoriginal Studyposted by Mike Williams-Rice on August 18 2014it s easy to accidentally introduce impurities to graphene
They expect the finding to be important to manufacturers considering the use of graphene in electronic devices.
Even a single molecule of a foreign substance can contaminate graphene enough to affect its electrical and optical properties says Junichiro Kono of Rice university.
The researchers used it as a substrate for graphene. Hitting the combined material with femtosecond pulses from a near-infrared laser prompted the indium phosphide to emit terahertz back through the graphene.
Imperfections as small as a stray oxygen molecule on the graphene were picked up by a spectrometer. he change in the terahertz signal due to adsorption of molecules is remarkablekono says. ot just the intensity
but also the waveform of emitted terahertz radiation totally and dynamically changes in response to molecular adsorption and desorption.
and changes over time. he laser gradually removes oxygen molecules from the graphene changing its density
The experiment involved growing pristine graphene via chemical vapor deposition and transferring it to an indium phosphide substrate.
Laser pulses generated coherent bursts of terahertz radiation through a built-in surface electric field of the indium phosphide substrate that changed due to charge transfer between the graphene and the contaminating molecules.
or any future device designs using graphene we have to take into account the influence of the surroundingssays Kono.
Graphene in a vacuum or sandwiched between noncontaminating layers would probably be stable but exposure to air would contaminate it he says.
and Masayoshi Tonouchi at Osaka s Institute of Laser Engineering are continuing to collaborate on a project to measure the terahertz conductivity of graphene on various substrates says Kono.
and nanotubes Stanford university rightoriginal Studyposted by Bjorn Carey-Stanford on August 7 2014by injecting carbon nanotubes into the bloodstream scientists can use near-infrared lasers to see blood flow in a living animal s brain.
or NIR-IIA involves injectingâ water-soluble carbon nanotubes into a live mouse s bloodstream. The researchers then shine a near-infrared laser over the rodent s skull.
The light causes the specially designed nanotubes to fluoresce at wavelengths of 1300-1400 nanometers;
The fluorescing nanotubes can then be detected to visualize the blood vessels structure. Amazingly the technique allows scientists to view about three millimeters underneath the scalp
Second injecting carbon nanotubes needs approval for clinical application; the scientists are currently investigating alternative fluorescent agents.
and the nanosensor at high frequencieskulkarni says. This technique made possible through the use of graphene results in extremely fast response times of tenths of a second as opposed to the tens or hundreds of seconds typical in existing technology.
It also dramatically increases the device's sensitivity. The sensor can detect molecules in sample sizes at a ratio of several parts per billion.
These nanoelectronic graphene vapor sensors can be embedded completely in a microgas chromatography system which is the gold standard for vapor analysis the researchers say.
Previously it was impossible to make nanopillars through cheap molding processes because the pillars were made from materials that preferred adhering to the mold rather than whatever surface they were supposed to cover.
The usual material for making nanopillars is too brittle to survive handling well. The team demonstrated the nanopillars could stick to plastics fabric paper
and metal and they anticipate that the arrays will also transfer easily to glass and leather.
Stretching the material known as carbyne a hard-to-make one-dimensional chain of carbon atoms by just 3 percent can begin to change its properties in ways that engineers might find useful for mechanically activated nanoscale electronics and optics.
The results published in the journal Nature Nanotechnology are much more sensitive than those for other optical sensors says Xiang Zhang professor of mechanical engineering at University of California Berkeley. ptical explosive sensors are very sensitive
and director at UC Berkeley of the National Science Foundation Nanoscale Science and Engineering Center. he ability to magnify such a small trace of an explosive to create a detectable signal is a major development in plasmonsensor technology
The nanoscale plasmon sensor used in the lab experiments is much smaller than other explosive detectors on the market.
#Stretchy, bendy, stronger-than-ever graphene fiber Researchers have created a simple and scalable method of making strong,
stretchable graphene oxide fibers that are scrolled easily into yarns and have strengths approaching that of Kevlar. This method opens up multiple possibilities for useful products.
For instance, removing oxygen from the graphene oxide fiber results in a fiber with high electrical conductivity. Adding silver nanorods to the graphene film would increase the conductivity to the same as copper,
which could make it a much lighter weight replacement for copper transmission lines. In addition, the researchers believe that the material lends itself to many kinds of highly sensitive sensors. e found this graphene oxide fiber was very strong
much better than other carbon fibers, says Mauricio Terrones, professor of physics, chemistry and materials science and engineering,
GRAPHENE SLURRY FILM The researchers made a thin film of graphene oxide by chemically exfoliating graphite into graphene flakes,
The Research center for Exotic Nanocarbons in Japan and the Center for Nanoscale Science at Penn State supported the research u
A new one-step process to etch nanoscale spikes into silicon lets the maximum amount of sunlight reach a solar cell,
and wavelength, says Andrew Barron, professor of chemistry and of materials science and nanoengineering at Rice university.
Black silicon is simply silicon with a highly textured surface of nanoscale spikes or pores that are smaller than the wavelength of light.
the phosphorous acid reduces the copper ions to copper nanoparticles. The nanoparticles attract electrons from the silicon wafer surface,
oxidizing it and allowing hydrogen fluoride to burn inverted pyramid-shaped nanopores into the silicon. Fine-tuning the process resulted in a black silicon layer with pores as small as 590 nanometers (billionths of a meter) that let through more than 99 percent of light.
By comparison, a clean, un-etched silicon wafer reflects nearly 100 percent of light. The spikes will still require a coating to protect them from the elements,
and Barron lab is working on ways to shorten the eight-hour process needed to perform the etching in the lab
University of Toronto rightoriginal Studyposted by Marit Mitchell-Toronto on June 9 2014those flat glassy solar panels on your neighborâ#roof may be getting a more efficient makeover thanks to a new class of solar-sensitive nanoparticles.
This new form of solid stable light-sensitive nanoparticles called colloidal quantum dots could lead to cheaper and more flexible solar cells as well as better gas sensors infrared lasers infrared light emitting diodes and more.
Collecting sunlight using these tiny colloidal quantum dots depends on two types of semiconductors: n-type which are rich in electrons and p-type
and demonstrated a new colloidal quantum dot n-type material that does not bind oxygen when exposed to air.
But improved performance is just a start for the new quantum dot-based solar cell architecture. The powerful little dots could be mixed into inks
and accessibility of solar power for millions of people. he field of colloidal quantum dot photovoltaics requires continued improvement in absolute performance
and enable the economic production of gas resources with higher carbon dioxide content that would be too costly to recover using current carbon capture technologies says James Tour professor of mechanical engineering and nanoengineering and of computer science at Rice university.
or PDMS, and carbon nanotubes. HOW IT WORKS When the terahertz light hits the transducer, the nanotubes absorb it,
turning it into heat. They pass that heat on to the PDMS. The heated PDMS expands,
Much of Reguera research with these bacteria focuses on engineering their conductive pili or nanowires.
He and graduate student Andrew Westover have built small aferdevices in the Nanomaterials and Energy Devices Laboratory there. ndrew has managed to make our dream of structural energy storage materials into a realitysays Pint.
because they go dead. estover s wafers consist of electrodes made from silicon that have been treated chemically so they have nanoscale pores on their inner surfaces
and then coated with a protective ultrathin graphene-like layer of carbon. Sandwiched between the two electrodes is a polymer film that acts as a reservoir of charged ions similar to the role of the electrolyte paste in a battery.
and solidifies it forms an extremely strong mechanical bond. he biggest problem with designing load-bearing supercaps is preventing them from delaminatingsays Westover. ombining nanoporous material with the polymer electrolyte bonds the layers together tighter than superglue. he use
and solar cells but Pint and Westover are confident that the rules that govern the load-bearing character of their design will carry over to other materials such as carbon nanotubes and lightweight porous metals like aluminum.
#DNA motor uses arms to walk across a nanotube Purdue University rightoriginal Studyposted by Emil Venere-Purdue on December 19 2013engineers made a motor out of DNA
and then used it to move nanoparticles of cadmium disulfide along the length of a nanotube.
New findings were detailed in a paper published this month in the journal Nature Nanotechnology.
As it moves along a carbon-nanotube track it continuously harvests energy from strands of RNA molecules vital to a variety of roles in living cells
and viruses. ur motors extract chemical energy from RNA molecules decorated on the nanotubes and use that energy to fuel autonomous walking along the carbon nanotube trackchoi says.
The core is made of an enzyme that cleaves off part of a strand of RNA. After cleavage the upper DNA arm moves forward binding with the next strand of RNA
The process repeats until reaching the end of the nanotube track. The researchers combined two fluorescent imaging systems to document the motor s movement one in the visible spectrum and the other in the near-infrared range.
The nanoparticle is fluorescent in visible light and the nanotubes are fluorescent in the near-infrared.
The motor took about 20 hours to reach the end of the nanotube which was several microns long
but the process might be sped up by changing temperature and ph a measure of acidity.
or the first time we predicted their properties using quantum mechanics. he nanocrystals are about 3 nanometers wide by 500 nanometers longor about 1/1000th the width of a grain of sandmaking them too small to study with light microscopes
The findings represent a milestone in understanding the fundamental mechanical behavior of the cellulose nanocrystals. t is also the first step towards a multiscale modeling approach to understand
and medical devices to structural components for the automotive civil and aerospace industries. he cellulose nanocrystals represent a potential green alternative to carbon nanotubes for reinforcing materials such as polymers and concrete.
and bacteria that create a protective web of cellulose. ith this in mind cellulose nanomaterials are inherently renewable sustainable biodegradable and carbon-neutral like the sources from
and infrastructure applications. or the future Wang and his research team plan to continue studying the nanogenerators
#Car paint with graphene gets ice off radar domes Rice university rightoriginal Studyposted by Mike Williams-Rice on December 18 2013ribbons of ultrathin graphene combined with polyurethane paint meant for cars can keep ice off of sensitive military
because they re very poor conductors. nter graphene the single-atom-thick sheet of carbon that both conducts electricity and because it s so thin allows radio frequencies to pass unhindered.
Spray-on deicing material that incorporates graphene nanoribbons would be lighter cheaper and more effective than current methods Tour says.
when (Lockheed martin engineer) Vladimir Volman saw a presentation by Yu Zhu a postdoc in my lab at the timehe says. olman had calculated that one could pass a current through a graphene film less than 100 nanometers thick
Zhu was presenting his technique for spraying nanoribbons films and Volman recognized the potential. ristine graphene transmits electricity ballistically
and would not produce enough heat to melt ice or keep it from forming but graphene nanoribbons (GNRS) unzipped from multiwalled carbon nanotubes in a chemical process invented by the Tour group in 2009 do the job nicely he says.
When evenly dispersed on a solid object the ribbons overlap and electrons pass from one to the next with just enough resistance to produce heat as a byproduct.
The 100-nanometer layer of GNRSÂ##thousands of times thinner than a human hairâ##was hooked to platinum electrodes.
Tour says the availability of nanoribbons is no longer an issue now that they re being produced in industrial quantities. ow we re going to the next levelhe says noting that GNR films made into transparent films might be useful for deicing car windshields a project the lab intends to pursue.
Volman suggests the material would make a compelling competitor to recently touted nanotube-based aerogels for deicing airplanes in the winter. e have the technology;
The metasurface thousands of V-shaped nanoantennas formed into an ultrathin gold foil could make possible lanar photonicsdevices
Laser light shines through the nanoantennas creating the hologram 10 microns above the metasurface. f we can shape characters we can shape different types of light beams for sensing
Nanostructured metamaterials however are making it possible to reduce the wavelength of light allowing the creation of new types of nanophotonic devices says Vladimir M. Shalaev scientific director of nanophotonics at Purdue s Birck Nanotechnology Center
and professor of electrical and computer engineering. he most important thing is that we can do this with a very thin layer only 30 nanometers
Under development for about 15 years metamaterials owe their unusual potential to precision design on the scale of nanometers.
and phase or timing of laser light as it passes through the nanoantennas. Each antenna has its own hase delayow much light is slowed as it passes through the structure.
#From coal, cheap quantum dots in one step Chemists have discovered how to reduce three kinds of coal into graphene quantum dots (GQDS) that could be used for medical imaging as well as sensing electronic and photovoltaic applications.
In quantum dots microscopic discs of atom-thick graphene oxide band gaps are responsible for their fluorescence and can be tuned by changing the dots'##size.
The new process described in the journal Nature Communications allows a measure of control over their size generally from 2 to 20 nanometers depending on the source of the coal.
That involved crushing the coal and bathing it in acid solutions to break the bonds that hold the tiny graphene domains together. ou can'##t just take a piece of graphene
Bituminous coal produced GQDS between 2 and 4 nanometers wide. Coke produced GQDS between 4 and 8 nanometers and anthracite made stacked structures from 18 to 40 nanometers with small round layers atop larger thinner layers.
Just to see what would happen the researchers treated graphite flakes with the same process
A small change in the size of a quantum dot as little as a fraction of a nanometer##changes its fluorescent wavelengths by a measurable factor
So this discovery can really change the quantum dot industry. It'#going to show the world that inside of coal are these very interesting structures that have real value. he Air force Office of Scientific research
and effective blockage of oil spreading. ur work is based on micro/nanoelectromechanical systems or M/NEMS
or mechanical structures that allow researchers to conduct their work on the micro/nanoscopic levelsays Jae Kwon associate professor of electrical and computer engineering at the University of Missouri. il-based materials or low-surface tension liquids
and virtual walls for low-surface tension liquids also have immense potential for many lab-on-a-chip devices
#DNA helps nanoparticle crystals self-assemble Northwestern University rightoriginal Studyposted by Megan Fellman-Northwestern on December 2 2013using the same structure found in nature researchers have built the first near-perfect single crystals
out of gold nanoparticles and DNA. ingle crystals are the backbone of many things we rely onâ##diamonds for beauty as well as industrial applications sapphires for lasers
and silicon for electronicssays nanoscientist Chad A. Mirkin. he precise placement of atoms within a well-defined lattice defines these high-quality crystals. ow we can do the same with nanomaterials
research group developed the ecipefor using nanomaterials as atoms DNA as bonds and a little heat to form tiny crystals.
Given a set of nanoparticles and a specific type of DNA Olvera de la Cruz showed they can accurately predict the 3d structure
The team worked with gold nanoparticles but the recipe can be applied to a variety of materials with potential applications in the fields of materials science photonics electronics
In the study strands of COMPLEMENTARY DNA act as bonds between disordered gold nanoparticles transforming them into an orderly crystal.
The researchers determined that the ratio of the DNA linker s length to the size of the nanoparticle is critical. f you get the right ratio it makes a perfect crystalâ##isn t that fun?
and realized experimentally. o achieve a self-assembling single crystal in the lab the research team reports taking two sets of gold nanoparticles outfitted with COMPLEMENTARY DNA
Working with approximately 1 million nanoparticles in water they heated the solution to a temperature just above the DNA linkers melting point
The researchers determined that the length of DNA connected to each gold nanoparticle can t be much longer than the size of the nanoparticle.
In the study the gold nanoparticles varied from five to 20 nanometers in diameter; for each the DNA length that led to crystal formation was about 18 base pairs and six single-base ticky ends.?
There s no reason we can t grow extraordinarily large single crystals in the future using modifications of our techniquesays Mirkin who also is a professor of medicine chemical and biological engineering biomedical engineering and materials science and engineering and director of the university s International Institute for Nanotechnology.
engineers turned to atomically thin graphene. James Hone a mechanical engineering professor at Columbia University who co-led the project says the work emonstrates an application of graphene that cannot be achieved using conventional materials.
And it s an important first step in advancing wireless signal processing and designing ultrathin efficient cell phones. ur devices are much smaller than any other sources of radio signals
The combination of these properties makes graphene an ideal material for nanoelectromechanical systems (NEMS) which are scaled-down versions of the microelectromechanical systems (MEMS) used widely for sensing of vibration and acceleration.
For example Hone explains MEMS sensors figure out how your smartphone or tablet is tilted to rotate the screen.
In this new study published in Nature Nanotechnology the team took advantage of graphene s mechanical tretchabilityto tune the output frequency of their custom oscillator creating a nanomechanical version of an electronic component known as a voltage controlled oscillator (VCO.
The team built a graphene NEMS whose frequency was about 100 megahertz which lies right in the middle of the FM radio band (87.7 to 108 MHZ).
They used low-frequency musical signals (both pure tones and songs from an iphone) to modulate the 100 MHZ carrier signal from the graphene
While graphene NEMS will not be used to replace conventional radio transmitters they have many applications in wireless signal processing. ue to the continuous shrinking of electrical circuits known as Moore s Law today s cell phones have more computing
and their frequency can be tuned over a wide range because of graphene s tremendous mechanical strength. here is a long way to go toward actual applications in this areanotes Hone ut this work is an important first step.
and Shepard groups are now working on improving the performance of the graphene oscillators to have lower noise.
At the same time they are also trying to demonstrate integration of graphene NEMS with silicon integrated circuits making the oscillator design even more compact.
For the battery project Chao added tiny nanoparticles of carbon to the polymer so it would conduct electricity. e found that silicon electrodes lasted 10 times longer
#Tiny Lego blocks build two-faced nanotubes University of Warwick rightoriginal Studyposted by Anna Blackaby-Warwick on November 14 2013using a process similar to molecular Lego scientists
and can be controlled with a much higher level of accuracy than natural channel proteins. hrough a process of molecular engineeringâ##a bit like molecular Legoâ##we have assembled the nanotubes from two types of building blocksâ##cyclic peptides
and polymers. anus nanotubes are a versatile platform for the design of exciting materials which have a wide range of application from membranesâ##for instance for the purification of waterâ##to therapeutic uses including the development of new drug systems. ource:
and stabilize the sulfur the researchers used amylopectin a polysaccharide that s a main component of corn starch. he corn starch can effectively wrap the graphene oxide-sulfide composite through the hydrogen bonding to confine the polysulfide among the carbon layerssays Hao Chen
to make lithium-sulfur cathodes by synthesizing a nanocomposite consisting of sulfur coated with a common inexpensive conductive polymer called polyaniline and
However they have been catching up rapidly. he big challenge for this approach is assembling the materialssays Pint. onstructing high-performance functional devices out of nanoscale building blocks with any level of control has proven to be quite challenging
they used porous silicon a material with a controllable and well-defined nanostructure made by electrochemically etching the surface of a silicon wafer.
This allowed them to create surfaces with optimal nanostructures for supercapacitor electrodes but it left them with a major problem.
With experience in growing carbon nanostructures Pint s group decided to try to coat the porous silicon surface with carbon. e had no idea
what would happensays Pint. ypically researchers grow graphene from silicon-carbide materials at temperatures in excess of 1400 degrees Celsius.
But at lower temperatures 600 to 700 degrees Celsius we certainly didn t expect graphene-like material growth. hen the researchers pulled the porous silicon out of the furnace they found that it had turned from orange to purple or black.
but it was coated by a layer of graphene a few nanometers thick. They tested the coated material
And when they used it to make supercapacitors they found that the graphene coating improved energy densities by over two orders of magnitude compared to those made from uncoated porous silicon and significantly better than commercial supercapacitors.
The graphene layer acts as an atomically thin protective coating. Pint and his group argue that this approach isn t limited to graphene. he ability to engineer surfaces with atomically thin layers of materials combined with the control achieved in designing porous materials opens opportunities for a number of different applications beyond energy storagehe
says. espite the excellent device performance we achieved our goal wasn t to create devices with record performancesays Pint. t was to develop a road map for integrated energy storage.
which is made typically of tungsten##an abundant material also used in conventional light bulbs. ur thermal emitters have a complex three-dimensional nanostructure that has to withstand temperatures above 1800 F 1000 C to be practicalbraun says n fact the hotter
however the 3-D structure of the emitter was destroyed at temperatures of around 1800 F (1000 C). To address the problem Braun and his Illinois colleagues coated tungsten emitters in a nanolayer of a ceramic material called hafnium
#Nanoribbon material keeps gases captive Rice university rightoriginal Studyposted by Mike Williams-Rice on October 11 2013an enhanced polymer could make vehicles that run on compressed natural gas more practical and even prolong the shelf life of bottled beer
By adding modified single-atom-thick graphene nanoribbons (GNRS) to thermoplastic polyurethane (TPU) the team at Rice made it 1000 times harder for gas molecules to escape Tour says.
The researchers acknowledge that a solid two-dimensional sheet of graphene might be the perfect barrier to gas
but the production of graphene in such bulk quantities is not yet practical Tour says. But graphene nanoribbons are already there.
Tour s breakthrough nzippingtechnique for turning multiwalled carbon nanotubes into GNRS first revealed in Nature in 2009 has been licensed for industrial production. hese are being produced in bulk
which should also make containers cheaperhe says. The researchers led by Rice graduate student Changsheng Xiang produced thin films of the composite material by solution casting GNRS treated with hexadecane and TPU a block copolymer of polyurethane that combines hard and soft materials.
But the overlapping 200-to 300-nanometer-wide ribbons dispersed so well that they were nearly as effective as large-sheet graphene in containing gas molecules.
The GNRS geometry makes them far better than graphene sheets for processing into composites Tour says.
The Air force Research Laboratory through the University Technology Corp. the Office of Naval Research MURI graphene program and the Air force Office of Scientific research MURI program supported the research.
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