SI
SI
discoversearch

 Non-Tech | Graphene


Previous 10 | Next 10 
From: DanD10/28/2011 9:29:17 PM
   of 206
 

Graphene robot has some smooth moves

27 October 2011







The graphene robot can pick up a round object, move it and drop it into a container, all controlled by infrared light

A remote controlled graphene-based robot that picks up an object, moves it to a desired location and then drops it, has been developed by scientists in China. The robot could be used to perform surgery that is not easily done by hand.

Yi Xie at the University of Science and Technology of China, Hefei, and colleagues made the robot by combining an actuator, a device that converts energy into motion, with an electronic device, which responds to infrared light to curl and uncurl to pick up and drop objects.

'Integrating microelectronic devices with micromechanical devices represents an important step for developing intelligent electronics,' says Xie. 'Transparent flexible electronics such as fold-out displays have received considerable attention, but integrating actuators with electronic devices requires excellent mechanical actuating behaviour and high transparency.' So far, it has been difficult to find suitable transparent materials, adds Xie.

The team prepared the actuator by layering a polyethylene film onto a glass layer. On top of this, they added a graphene layer, which can absorb infrared light and convert this energy into heat with a high efficiency. The graphene - a sheet of carbon atoms one atom thick - also combines high transparency with strong mechanical performance. A strip of graphene on polyethylene that was 3mm by 12mm was then cut out and peeled off the glass, after which the strip curled up.

The team found that the strip uncurled in the presence of infrared light so switching the IR light on and off transformed the strip into a moving robot. The team demonstrated that their robot could pick up a small round object, move it and drop it into a container. They placed the uncurled strip above the object and turned the infrared light on, making the strip curl around the object. With the object in its grip, the strip was moved to a container, the infrared light was switched off, and the strip uncurled to drop its cargo.

'This is an elegant demonstration of photothermal energy conversion by graphene oxide based actuators,' says Jiaxing Huang, who studies graphene-based functional materials at Northwestern University in the US. 'It could inspire the design of transparent artificial muscles.'

Elinor Richards


Share Recommend | Keep | Reply | Mark as Last Read

From: DanD10/31/2011 2:05:54 PM
   of 206
 
Korean researchers create stretchy transistors made of graphene

By Michael Gorman posted Oct 28th 2011 6:10AM








Graphene's greatness comes from its flexibility, both figurative -- you can make everything from transparent speakers to stain resistant pants with the stuff -- and literal. And now researchers in Korea have given us another pliable graphene product by creating a stretchy transistor from the carbon allotrope. The trick was accomplished by first layering sheets of graphene on copper foil and bonding it all to a rubber substrate. To complete the transistor channels were etched onto its surface, then electrodes and gate insulators made of ion gel were printed onto the device. What resulted was a transistor that could stretch up to five percent without losing any electrical efficiency, and the plan is to increase its elasticity through continued research. Keep up the good work, fellas, we can't wait for our flexible phone future.

Share Recommend | Keep | Reply | Mark as Last Read

From: DanD10/31/2011 4:24:20 PM
   of 206
 
Samsung to debut flexible smartphone screens in 2012
OCTOBER 31, 2011BY RICK MARSHALL



Industry-leading smartphone manufacturer plans new "twist" on display screen technology next year.

Not content with leading the industry in smartphone sales, Samsung also plans to offer the most flexible phones, too.

During its quarterly earnings call this week, the company announced plans to feature flexible screens on its mobile devices hitting shelves in 2012.

“The flexible display we are looking to introduce sometime in 2012, hopefully the earlier part,” said Samsung’s vice president of investor relations, Robert Yi. “The application probably will start from the handset side.”

The company plans to move on to tablet computers and other devices after phones, too.

Samsung has made rapid strides in bringing bendable screens to consumers after purchasing Liquivista, a company specializing in flexible electronic displays, back in January 2011. While many companies have been experimenting with bright, low-power displays that can also be flexed and twisted, this could be the first mass-market rollout for the technology.

At the 2009 CES, Sony demonstrated a flexible display, but it has yet to announce plans for a mass-market product featuring the screens.

Share Recommend | Keep | Reply | Mark as Last Read


From: DanD11/7/2011 10:25:50 AM
   of 206
 
VIDEO, how to make your own Graphene: youtube.com 

Share Recommend | Keep | Reply | Mark as Last Read

From: DanD11/12/2011 12:11:17 PM
   of 206
 
Cornell scientists review future of graphene November 9, 2011 By Anne Ju
Enlarge

A false-color microscopy image of a 30-by-30 micron square of graphene covering a square trench to form a nanomechanical resonator. These devices, which are the thinnest possible microelectromechanical systems and are useful for sensing and signal processing, can now be batch-fabricated as a result of recent advances in graphene fabrication technology.

(PhysOrg.com) -- Graphene is sort of a scientific rock star, with countless groups studying its amazing electrical properties and tensile strength and dreaming up applications ranging from flat-panel screens to elevators in space.




0




The single-layer carbon sheets' stellar qualities are only just being understood in all their capacities, say scientists at Cornell -- and researchers can dream big (or rather, very small) when it comes to everything graphene can offer.

That's what scientists in the lab of Harold Craighead, the Charles W. Lake Professor of Engineering, say in an American Vacuum Society online review article, Sept. 9, about graphene's present and future. The article made the cover of the printed journal and quickly became one of its most-downloaded pieces.

"It's becoming clear that with modern fabrication techniques, you can imagine turning graphene into a technology," said Robert A. Barton,graduate student and lead author. "People often focus on the electronic applications of graphene, and they don't really think as much of its mechanical applications."

It's precisely this area where Cornell has produced some pioneering work. In particular the Craighead group, in collaboration with others including Jiwoong Park, assistant professor of chemistry and chemical biology, and Paul McEuen, the Goldwin Smith Professor of Physics, has used graphene in nanoelectromechanical systems (NEMS), analogous to an earlier generation's microelectromechanical systems (MEMS).

"We've moved beyond working with little exfoliated flakes and more with grown materials that can be incorporated and connected with electronics and other mechanics," Craighead said. "So the question is, can you make these reliably, uniformly and reproducibly?"

It was only a few years ago that scientists figured out how to make arrays of hundreds of thousands of graphene devices using a process called chemical vapor deposition. This involves growing the single-layer sheets of honeycomb-latticed carbon atoms on top of copper, then manipulating the graphene to make devices.



One of the Cornell researchers' devices is like a drum head -- a piece of graphene, one atom thick, suspended over a hollow well. Although growth of graphene by chemical vapor deposition on copper was invented elsewhere, Cornell researchers were the first to figure out how to make mechanical resonators from the large-area material.

"Four years ago we were able to make about one, and that took several months," Barton said. Speeding up the fabrication process has greatly increased graphene's potential in devices.

At Cornell, Barton and colleagues are working on making mass sensors out of graphene, which is atomically structured so it's sensitive to both mass and electric charge. What can result is that a bit of mass landing on a surface of suspended graphene will perturb the mechanical and electronic structure simultaneously, analogous to today's mass spectrometry but on a much smaller and more sensitive level, Barton explained.

The Cornell researchers are using optical interferometry to monitor the motion of a sheet of graphene. In this technique, the subtle device motions are read as variations in reflected light intensity, which are monitored by a fast photodiode connected to a spectrum analyzer. Another group at Cornell, led by McEuen, had earlier developed a way to "read out" carbon nanotubes, a technique that can also apply to graphene, Barton said.

The rapid progress of graphene makes its future very exciting, Craighead said.

"Graphene has gone from an oddity in a physics lab to something that can be practically incorporated into a variety of potential devices," he said. "The ability to fabricate things in these ways, to integrate them and to use them for different types of sensors, physical and chemical, is quite a step forward in a short time, and our group is one of the many that's contributed to this."


Provided by Cornell University ( news : web)

Share Recommend | Keep | Reply | Mark as Last Read

From: DanD11/13/2011 2:25:32 PM
   of 206
 


Northern Graphite Corporation

TSX VENTURE : NGC




July 21, 2011 09:15 ET

Northern Graphite Announces Successful Test Production of Graphene




OTTAWA, ONTARIO--(Marketwire - July 21, 2011) - Northern Graphite Corporation (TSX VENTURE:NGC) is pleased to announce that graphene has been successfully made on a test basis using large flake graphite from the Company's Bissett Creek project in Northern Ontario. Northern's standard 95%C, large flake graphite was evaluated as a source material for making graphene by an eminent professor in the field at the Chinese Academy of Sciences who is doing research making graphene sheets larger than 30cm2 in size using the graphene oxide methodology. The tests indicated that graphene made from Northern's jumbo flake is superior to Chinese powder and large flake graphite in terms of size, higher electrical conductivity, lower resistance and greater transparency (see table).


Graphene sizeOpto-electrical propertiesGraphene area
(mm2)Percent
(%)Transmittance
(%)Sheet resistance
(O/sq)Chinese graphite powder (800mesh)0.04-0.36497912000Chinese flake graphite (32mesh)n¦Ñ70005678840Northern Graphiten¦Ñ100006481800
To view images of the graphenes, please visit the following link : media3.marketwire.com 

Approximately 70% of production from the Bissett Creek property will be large flake (+80 mesh) and almost all of this will in fact be +48 mesh jumbo flake which is expected to attract premium pricing and be a better source material for the potential manufacture of graphene. The very high percentage of large flakes makes Bissett Creek unique compared to most graphite deposits worldwide which produce a blend of large, medium and small flakes, as well as a large percentage of low value -150 mesh flake and amorphous powder which are not suitable for graphene, Li ion batteries or other high end, high growth applications.

Graphite is one of only two naturally occurring forms of carbon, the other being diamonds. A graphite flake is much like a deck of cards, it consists of many thin layers stacked one on top of the other with weak bonds holding them together. Delaminating these layers to the lowest common denominator results in a one atom thick sheet of carbon with the carbon atoms arranged in a honeycomb pattern. This is graphene.

Graphene was first isolated by scientists at the University of Manchester who won the Noble Prize for Physics in 2010 for their efforts. Graphene is transparent in infra-red and visible light, flexible, and stronger than steel. It conducts heat 10 times faster than copper and can carry 1,000 times the density of electrical current of copper wire. Graphene is expected to be a revolutionary material that could change the technology of semi conductors and LCD touch screens and monitors, create super small transistors and super dense data storage, increase energy storage and solar cell efficiency, and will transform many other applications.

According to a professor at Georgia Tech University, there are nearly 200 companies, including Intel and IBM, currently involved in graphene research. In 2010 graphene was the subject of approximately 3,000 research papers and the European Union and South Korea have each recently started $1.5 billion efforts to build industrial scale, next generation display materials using graphene as a substitute for indium tin oxide("ITO"). The world has only 5-10 years of ITO reserves remaining and prices exceed US$700,000 per tonne.

See what is possible at: youtube.com 

About Northern Graphite Corporation

Northern Graphite Corporation (TSX VENTURE:NGC) holds a 100% interest in the Bissett Creek graphite project which is located 17kms from the Trans Canada highway between Ottawa and North Bay, Ontario. The Company is in the process of completing a bankable Final Feasibility Study and permitting with the objective of initiating construction, subject to the results of the study and the availability of financing, in the first part of 2012.

The Graphite Market

Graphite prices have increased substantially due to the ongoing modernization of China and other emerging economies which has resulted in strong demand from traditional steel and automotive markets. In addition, new applications such as lithium ion batteries, fuel cells and nuclear power have the potential to create significant incremental demand growth. However, production and exports from China, which produces 70% of the world's graphite, are expected to decline and an export tax and a licensing system have been instituted. Both the European Union and the United States have declared graphite a supply critical mineral. With few potential development projects on the horizon, the Company is well positioned to benefit from the continued improvement in graphite demand and prices. High growth, high value graphite applications require large flake and/or high purity graphite which will represent 100% of Bissett Creek production.

Additional information on Northern Graphite Corporation can be found under the Company's profile on SEDAR at www.sedar.com and on the Company's website at www.northerngraphite.com

This press release contains forward-looking statements, which can be identified by the use of statements that include words such as "could", "potential", "believe", "expect", "anticipate", "intend", "plan", "likely", "will" or other similar words or phrases. These statements are only current predictions and are subject to known and unknown risks, uncertainties and other factors that may cause our or our industry's actual results, levels of activity, performance or achievements to be materially different from those anticipated by the forward-looking statements.The Company does not intend, and does not assume any obligation, to update forward-looking statements, whether as a result of new information, future events or otherwise, unless otherwise required by applicable securities laws. Readers should not place undue reliance on forward-looking statements.


Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release.




marketwire.com 

Share Recommend | Keep | Reply | Mark as Last Read


From: DanD11/26/2011 1:08:23 PM
   of 206
 


Graphene ink created for ink-jet printing of electronic components
November 25th, 2011 in Nanotechnology / Nanomaterials
Enlarge




Dark ?eld optical micrograph of inkjet printed drops on a) plasma cleaned, b) pristine and c) HMDS treated substrate. Scale: 20µm. d) SEM micrograph of printed pattern. Image from arXiv:1111.4970v1 [cond-mat.mtrl-sci]



(PhysOrg.com) -- A group of UK scientists has created a graphene ink that can be used to ink-jet print electronic devices such as thin film transistors.

Professor of Nanotechnology, Andrea Ferrari, and colleagues from the Engineering Department at the University of Cambridge have developed a method of creating a graphene ink that can be used with a modified ink-jet printer. Graphene consists of a hexagonal latticeof carbon only one atom thick, and has great advantages over polymer inks because of its greater electron mobility and electrical conductivity. Electronic components such as thin film transistors (TFTs) can already be created using ink-jet printing with ferro-electric polymer inks, but the performance of such components is poor and they are too slow for many applications.

Beginning with flakes of pure graphite, the team exfoliated layers of graphene using liquid phase exfoliation (LPE), which consists of sonication of the graphite in the presence of a solvent, N-Methylpyrrolidone (NMP). The graphene layers were ultracentrifuged and then filtered to remove any particles large enough (>1µm in diameter) to block the ink-jet printer heads. The graphene flakes were then used as the basis for a graphene-polymer ink, which was printed, using a modified ink-jet printer, onto Si/SiO2 substrates and the transparent substrate borosilicate glass. The final step in the process was annealing at high temperature to remove the solvent.

They demonstrated the new transparent graphene ink by using it to ink-jet print thin-film transistors, which they made by printing the graphene ink on Si/SiO2 wafers. They used chromium-gold pads to define the source and drain contacts, and they then printed a layer of an organic polymer, PQT-12, on top.

The team achieved promising results at least comparable to current inks. They achieved mobilities of up to around 95cm2V-1s-1, about 80% transmittance and 30kohm sheet resistance. Non-graphene polymer inks typically achieve mobilities of less than 0.5cm2V-1s-1, while adding carbon nanotubes can increase this to around 50cm2V-1s-1.

The results should improve as the method is refined and enhanced. Their successful first demonstration paves the way for the development of flexible and cheap electronics that can be printed on a wide variety of substrates. Devices printed using graphene inks could include wearable computers, electrical paper, sensors, electronic tags, and flexible touch screens.

The paper is available online from arXiv.org.

More information: Ink-Jet Printed Graphene Electronics, arXiv:1111.4970v1 [cond-mat.mtrl-sci] arxiv.org 

Abstract
We demonstrate ink-jet printing as a viable method for large area fabrication of graphene devices. We produce a graphene-based ink by liquid phase exfoliation of graphite in N-Methylpyrrolidone. We use it to print thin-film transistors, with mobilities up to~95cm^2V^(-1)s(-1), as well as transparent and conductive patterns, with~80 % transmittance and~30kOhm/sq sheet resistance. This paves the way to all-printed, flexible and transparent graphene devices on arbitrary substrates.


© 2011 PhysOrg.com


"Graphene ink created for ink-jet printing of electronic components." November 25th, 2011. physorg.com 

Share Recommend | Keep | Reply | Mark as Last Read

From: DanD11/26/2011 1:11:22 PM
   of 206
 


Graphene foam detects explosives, emissions better than today's gas sensors
November 24th, 2011 in Nanotechnology / Nanomaterials
Enlarge




Photo Credit: Nikhil Koratkar



(PhysOrg.com) -- A new study from Rensselaer Polytechnic Institute demonstrates how graphene foam can outperform leading commercial gas sensors in detecting potentially dangerous and explosive chemicals. The discovery opens the door for a new generation of gas sensors to be used by bomb squads, law enforcement officials, defense organizations, and in various industrial settings.

The new sensor successfully and repeatedly measured ammonia (NH3) and nitrogen dioxide (NO2) at concentrations as small as 20 parts-per-million. Made from continuous graphene nanosheets that grow into a foam-like structure about the size of a postage stamp and thickness of felt, the sensor is flexible, rugged, and finally overcomes the shortcomings that have prevented nanostructure-based gas detectors from reaching the marketplace.

Results of the study were published today in the journal Scientific Reports, published by Nature Publishing Group. See the paper, titled “ High Sensitivity Gas Detection Using a Macroscopic Three-Dimensional Graphene Foam Network.”

“We are very excited about this new discovery, which we think could lead to new commercial gas sensors,” said Rensselaer Engineering Professor Nikhil Koratkar, who co-led the study along with Professor Hui-Ming Cheng at the Shenyang National Laboratory for Materials Science at the Chinese Academy of Sciences. “So far, the sensors have shown to be significantly more sensitive at detecting ammonia and nitrogen dioxide at room temperature than the commercial gas detectors on the market today.”



This video is not supported by your browser at this time.

Watch a short video of Koratkar talking about this research

Over the past decade researchers have shown that individual nanostructures are extremely sensitive to chemicals and different gases. To build and operate a device using an individual nanostructure for gas detection, however, has proven to be far too complex, expensive, and unreliable to be commercially viable, Koratkar said. Such an endeavor would involve creating and manipulating the position of the individual nanostructure, locating it using microscopy, using lithography to apply gold contacts, followed by other slow, costly steps. Embedded within a handheld device, such a single nanostructure can be easily damaged and rendered inoperable. Additionally, it can be challenging to “clean” the detected gas from the single nanostructure.

The new postage stamp-sized structure developed by Koratkar has all of the same attractive properties as an individual nanostructure, but is much easier to work with because of its large, macroscale size. Koratkar’s collaborators at the Chinese Academy of Sciences grew graphene on a structure of nickel foam. After removing the nickel foam, what’s left is a large, free-standing network of foam-like graphene. Essentially a single layer of the graphite found commonly in our pencils or the charcoal we burn on our barbeques, graphene is an atom-thick sheet of carbon atoms arranged like a nanoscale chicken-wire fence. The walls of the foam-like graphene sensor are comprised of continuous graphene sheets without any physical breaks or interfaces between the sheets.

Koartkar and his students developed the idea to use this graphene foam structure as a gas detector. As a result of exposing the graphene foam to air contaminated with trace amounts of ammonia or nitrogen dioxide, the researchers found that the gas particles stuck, or adsorbed, to the foam’s surface. This change in surface chemistry has a distinct impact upon the electrical resistance of the graphene. Measuring this change in resistance is the mechanism by which the sensor can detect different gases.



Credit: Nikhil Koratkar

Additionally, the graphene foam gas detector is very convenient to clean. By applying a ~100 milliampere current through the graphene structure, Koratkar’s team was able to heat the graphene foam enough to unattach, or desorb, all of the adsorbed gas particles. This cleaning mechanism has no impact on the graphene foam’s ability to detect gases, which means the detection process is fully reversible and a device based on this new technology would be low power—no need for external heaters to clean the foam—and reusable.

Koratkar chose ammonia as a test gas to demonstrate the proof-of-concept for this new detector. Ammonium nitrate is present in many explosives and is known to gradually decompose and release trace amounts of ammonia. As a result, ammonia detectors are often used to test for the presence of an explosive. A toxic gas, ammonia also is used in a variety of industrial and medical processes, for which detectors are necessary to monitor for leaks.

Results of the study show the new graphene foam structure detected ammonia at 1,000 parts-per-million in 5 to 10 minutes at room temperature and atmospheric pressure. The accompanying change in the graphene’s electrical resistance was about 30 percent. This compared favorably to commercially available conducting polymer sensors, which undergo a 30 percent resistance change in 5 to 10 minutes when exposed to 10,000 parts-per-million of ammonia. In the same time frame and with the same change in resistance, the graphene foam detector was 10 times as sensitive. The graphene foam detector’s sensitivity is effective down to 20 parts-per-million, much lower than the commercially available devices. Additionally, many of the commercially available devices require high power consumption since they provide adequate sensitivity only at high temperatures, whereas the graphene foam detector operates at room temperature.

Koratkar’s team used nitrogen dioxide as the second test gas. Different explosives including nitrocellulose gradually degrade, and are known to produce nitrogen dioxide gas as a byproduct. As a result, nitrogen dioxide also is used as a marker when testing for explosives. Additionally, nitrogen dioxide is a common pollutant found in combustion and auto emissions. Many different environmental monitoring systems feature real-time nitrogen dioxide detection.

The new graphene foam sensor detected nitrogen dioxide at 100 parts-per-million by a 10 percent resistance change in 5 to 10 minutes at room temperature and atmospheric pressure. It showed to be 10 times more sensitive than commercial conducting polymer sensors, which typically detect nitrogen dioxide at 1,000 part-per-million in the same time and with the same resistance chance at room temperature. Other nitrogen dioxide detectors available today require high power consumption and high temperatures to provide adequate sensitivity. The graphene foam sensor can detect nitrogen dioxide down to 20 parts-per-million at room temperature.

“We see this as the first practical nanostructure-based gas detector that’s viable for commercialization,” said Koratkar, a professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer. “Our results show the graphene foam is able to detect ammonia and nitrogen dioxide at a concentration that is an order of magnitude lower than commercial gas detectors on the market today.”

The graphene foam can be engineered to detect many different gases beyond ammonia and nitrogen dioxide, he said.

Studies have shown the electrical conductivity of an individual nanotube, nanowire, or graphene sheet is acutely sensitive to gas adsorbtion. But the small size of individual nanostructures made it costly and challenging to develop into a device, plus the structures are delicate and often don’t yield consistent results.

The new graphene foam gas sensor overcomes these challenges. It is easy to handle and manipulate because of its large, macroscale size. The sensor also is flexible, rugged, and robust enough to handle wear and tear inside of a device. Plus it is fully reversible, and the results it provides are consistent and repeatable. Most important, the graphene foam is highly sensitive, thanks to its 3-D, porous structure that allows gases to easily adsorb to its huge surface area. Despite its large size, the graphene foam structure essentially functions as a single nanostructure. There are no breaks in the graphene network, which means there are no interfaces to overcome, and electrons flow freely with little resistance. This adds to the foam’s sensitivity to gases.

“In a sense we have overcome the Achilles’ heel of nanotechnology for chemical sensing,” Koratkar said. “A single nanostructure works great, but doesn’t mean much when applied in a real device in the real world. When you try to scale it up to macroscale proportions, the interfaces defeats what you’re trying to accomplish, as the nanostructure’s properties are dominated by interfaces. Now we’re able to scale up graphene in a way that the interfaces are not present. This allows us to take advantage of the intrinsic properties of the nanostructure, yet work with a macroscopic structure that gives us repeatability, reliability, and robustness, but shows similar sensitivity to gas adsorbtion as a single nanostructure.”

Provided by Rensselaer Polytechnic Institute



"Graphene foam detects explosives, emissions better than today's gas sensors." November 24th, 2011. physorg.com 

Share Recommend | Keep | Reply | Mark as Last Read

From: DanD12/7/2011 4:02:38 PM
   of 206
 


IBM researchers demonstrate future of computing with graphene, racetrack and carbon nanotube breakthroughs
December 5th, 2011 in Nanotechnology / Nanophysics


Today at IEEE International Electron Devices Meeting, IBM scientists unveiled several exploratory research breakthroughs that could lead to major advancements in delivering dramatically smaller, faster and more powerful computer chips.

For more than 50 years, computer processors have increased in power and shrunk in size at a tremendous rate. However, today’s chip designers are hitting physical limitations with Moore’s Law, halting the pace of product innovation from scaling alone.

With virtually all electronic equipment today built on complementary-symmetry metal–oxide–semiconductor (CMOS) technology, there is an urgent need for new materials and circuit architecture designs compatible with this engineering process as the technology industry nears physical scalability limits of the silicon transistor.

Following years of key physics advances previously only achieved in a laboratory, IBM scientists successfully integrated the development and application of new materials and logic architectures on 200mm (eight inch) diameter wafers. These breakthroughs could potentially provide a new technological basis for the convergence of computing, communication, and consumer electronics.

Racetrack Memory

Racetrack memory combines the benefits of magnetic hard drives and solid-state memory to overcome challenges of growing memory demands and shrinking devices.

Proving this type of memory is feasible, today IBM researchers are detailing the first Racetrack memory device integrated with CMOS technology on 200mm wafers, culminating seven years of physics research.

The researchers demonstrated both read and write functionality on an array of 256 in-plane, magnetized horizontal racetracks. This development lays the foundation for further improving Racetrack memory’s density and reliability using perpendicular magnetized racetracks and three-dimensional architectures.

This breakthrough could lead to a new type of data-centric computing that allows massive amounts of stored information to be accessed in less than a billionth of a second.

Graphene

This first-ever CMOS-compatible graphene device can advance wireless communications, and enable new, high frequency devices, which can operate under adverse temperature and radiation conditions in areas such as security and medical applications.

The graphene integrated circuit, a frequency multiplier, is operational up to 5 GHz and stable up to 200 degrees Celcius. While detailed thermal stability still needs to be evaluated, these results are promising for graphene circuits to be used in high temperature environments.

New architecture flips the current graphene transistor structure on its head. Instead of trying to deposit gate dielectric on an inert graphene surface, the researchers developed a novel embedded gate structure that enables high device yield on a 200mm wafer.

Carbon Nanotubes

IBM researchers today demonstrated the first transistor with sub-10 nm channel lengths, outperforming the best competing silicon-based devices at these length scales.

While already being considered in varied applications ranging from solar cells to displays, it is expected that computers with in the next decade will use transistors with a channel length below 10 nm, a length scale at which conventional silicon technology will have extreme difficulty performing even with new advanced device architectures. The scaled carbon nanotube devices below 10nm gate length are a significant breakthrough for future applications in computing technology.

While often associated with improving switching speed (on-state), this breakthrough demonstrates for the first time that carbon nanotubes can provide excellent off-state behavior in extremely scaled devices-- better than what some theoretical estimates of tunneling current suggested.

Provided by IBM



"IBM researchers demonstrate future of computing with graphene, racetrack and carbon nanotube breakthroughs." December 5th, 2011.http://www.physorg.com/news/2011-12-ibm-future-graphene-racetrack-carbon.html

Share Recommend | Keep | Reply | Mark as Last Read


From: DanD12/10/2011 2:32:25 PM
   of 206
 


Functionalized graphene oxide plays part in next-generation oil-well drilling fluids
December 8th, 2011 in Nanotechnology / Nanomaterials
Enlarge




Microscopic, star-shaped flakes of functionalized graphene oxide plug holes in pores in a test of the material's ability to serve as a filter cake in fluids used to drill oil wells. The single-atom-thick flakes of treated carbon are pliable but among the strongest materials known. (Credit Tour Group/Rice University)



Graphene's star is rising as a material that could become essential to efficient, environmentally sound oil production. Rice University researchers are taking advantage of graphene's outstanding strength, light weight and solubility to enhance fluids used to drill oil wells.

The Rice University lab of chemist James Tour and scientists at M-I SWACO, a Texas-based supplier of drilling fluids and subsidiary of oil-services provider Schlumberger, have produced functionalized graphene oxide to alleviate the clogging of oil-producing pores in newly drilled wells.

The patented technique took a step closer to commercialization with the publication of new research this month in the American Chemical Society journal Applied Materials and Interfaces. Graphene is a one-atom-thick sheet of carbon that won its discoverers a Nobel Prize last year.

Rice's relationship with M-I SWACO began more than two years ago when the company funded the lab's follow-up to research that produced the first graphene additives for drilling fluids known as muds. These fluids are pumped downhole as part of the process to keep drill bits clean and remove cuttings. With traditional clay-enhanced muds, differential pressure forms a layer on the wellbore called a filter cake, which both keeps the oil from flowing out and drilling fluids from invading the tiny, oil-producing pores.

When the drill bit is removed and drilling fluid displaced, the formation oil forces remnants of the filter cake out of the pores as the well begins to produce. But sometimes the clay won't budge, and the well's productivity is reduced.

The Tour Group discovered that microscopic, pliable flakes of graphene can form a thinner, lighter filter cake. When they encounter a pore, the flakes fold in upon themselves and look something like starfish sucked into a hole. But when well pressure is relieved, the flakes are pushed back out by the oil.

All that was known two years ago. Since then, Tour and a research team led by Dmitry Kosynkin, a former Rice postdoctoral associate and now a petroleum engineer at Saudi Aramco, have been fine-tuning the materials.

They found a few issues that needed to be dealt with. First, pristine graphene is hard to disperse in water, so it is unsuitable for water-based muds. Graphene oxide (GO) turned out to be much more soluble in fresh water, but tended to coagulate in saltwater, the basis for many muds.

The solution was to "esterify" GO flakes with alcohol. "It's a simple, one-step reaction," said Tour, Rice's T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science. "Graphene oxide functionalized with alcohol works much better because it doesn't precipitate in the presence of salts. There's nothing exotic about it."

In a series of standard American Petroleum Institute tests, the team found the best mix of functionalized GO to be a combination of large flakes and powdered GO for reinforcement. A mud with 2 percent functionalized GO formed a filter cake an average of 22 micrometers wide -- substantially smaller than the 278-micrometer cake formed by traditional muds. GO blocked pores many times smaller than the flakes' original diameter by folding.

Aside from making the filter cake much thinner, which would give a drill bit more room to turn, the Rice mud contained less than half as many suspended solids; this would also make drilling more efficient as well as more environmentally friendly. Tour and Andreas Lüttge, a Rice professor of Earth science and chemistry, reported last year that GO is reduced to graphite, the material found in pencil lead and a natural mineral, by common bacteria.

"The most exciting aspect is the ability to modify the GO nanoparticle with a variety of functionalities," said James Friedheim, corporate director of fluids research and development at M-I SWACO and a co-author of the research. "Therefore we can 'dial in' our application by picking the right organic chemistry that will suit the purpose. The trick is just choosing the right chemistry for the right purpose."

"There's still a lot to be worked out," Tour said. "We're looking at the rheological properties, the changes in viscosity under shear. In other words, we want to know how viscous this becomes as it goes through a drill head, because that also has implications for efficiency."

Muds may help graphene live up to its commercial promise, Tour said. "Everybody thinks of graphene in electronics or in composites, but this would be a use for large amounts of graphene, and it could happen soon," he said.

Friedheim agreed. "With the team we currently have assembled, Jim Tour's group and some development scientists at M-I SWACO, I am confident that we are close to both technical and commercial success."

More information: Read the abstract at pubs.acs.org 


Provided by Rice University



"Functionalized graphene oxide plays part in next-generation oil-well drilling fluids." December 8th, 2011. physorg.com 

Share Recommend | Keep | Reply | Mark as Last Read
Previous 10 | Next 10 

Copyright © 1995-2014 Knight Sac Media. All rights reserved.Stock quotes are delayed at least 15 minutes - See Terms of Use.