Print Page | Contact Us | Report Abuse | Sign In | Register
Graphene Updates
Blog Home All Blogs

CEALTECH

Posted By Terrance Barkan, Tuesday, December 20, 2016
Share |
PermalinkComments (0)
 

IDTechEx USA 2016 Highlights Graphene Developments

Posted By Terrance Barkan, Friday, December 2, 2016

The Graphene Council participated at the IDTechEx conference in Santa Clara, California on 16-17 November 2016. The event brought together more than 3,000 attendees to learn about the latest developments in graphene, 3D printing, electric vehicles, flexible electronics and related technologies. 

What was very noticeable during this event was the clearly increasing interest from large industrial companies in the application of graphene in their current and future products. Companies like Ford Motors, GE, Dupont, Siemens, Lockheed Martin and many others. 

The range of applications runs from super hydrophobic coatings to heat management systems using graphene in combination with other materials. 

It was also a great opportunity for graphene producers like Applied Graphene Materials, Perpetuus and Graphenea, graphene material specialist firm Haydale and high quality graphite supplier First Graphite from Australia to exhibit their knowledge, products and capabilities.

We have a winner!

The Graphene Council held a drawing for visitors to our stand and we are very pleased to announce that Dr. Alison Schultz, advanced scientist for Owens Corning, was selected as the winner!

Alison attended the University of Rhode Island for her undergraduate studies where she earned a B.S. in Chemistry and Spanish. She then pursued a graduate career with Prof. Timothy E. Long at Virginia Tech, ultimately receiving her Ph.D. in Polymer Chemistry. Her research dissertation concentrated on ion-containing macromolecules for the production of thermally stable compositions with tunable physical and mechanical properties, targeting technologies ranging from electro-active membranes to high performance adhesives.

Alison is now working as an advanced scientist for Owens Corning within the Front End of Innovation (FEI) group. She is interested in exploring and leveraging new graphene technologies to improve electrical, mechanical, and barrier properties for a variety of composites. A major aspect of this endeavor involves understanding graphene's dispersion with various solvents and polymeric resins. To accomplish this goal, she is actively seeking new collaborative opportunities with graphene companies.

Alison can be reached at: Alison.Schultz@owenscorning.com

IDTechEx Europe 10-11 May 2017 in Berlin

The Graphene Council will participate at the next major graphene commercialization conference to be held in Berlin on 10-11 May 2017. We are preparing special presentations and important announcements regarding graphene standards, the establishment of a health and safety task force, a certification program for graphene producers and more. Stay tuned!

If you would like more information about how to participate as an exhibitor in a dedicated "Graphene Pavilion" or to simply attend as a participant at favorable discount rates, contact me directly at: tbarkan@thegraphenecouncil.org

We expect 2017 to be a year of increased public announcements of commercial applications of graphene as well as significant increases in industry scale production volumes. 

The Graphene Council's mission is to serve the global graphene community and help to accelerate the commercialization of this unique and multifunctional material. 

 

This post has not been tagged.

Share |
PermalinkComments (0)
 

2D materials - Graphene and hBN (hexagonal boron nitride) enhances methanol fuel cell performance

Posted By Terrance Barkan, Tuesday, November 29, 2016

This is an authorized reprint of a recent publication in Advanced Energy Materials journal (Impact Factor: 16) (http://dx.doi.org/10.1002/aenm.201601216), by Stuart M. Holmes (Reader) and Prabhuraj - (PhD student - http://www.prabhuraj.co.uk/) from the School of Chemical Engineering and Analytical Science, University of Manchester in collaboration with the School of Physics, reporting the usage of 2D materials in operating direct methanol fuel cells, showing zero resistance to protons enhancing cell performance, thereby opening the bottle neck for commercialization of fuel cells. 

The content published is the sole responsibility of the authors. 

Fuel cells are an interesting energy technology for the near future, as they aid in production of sustainable energy using hydrocarbons as fuels, such as methanol, ethanol, acetone etc by a simple oxidation-reduction reaction mechanism.

Among different liquid fuels, methanol is attractive as it has a higher energy density (compared to lithium ion batteries and hydrogen) and other features such as ease in handling, availability etc. Hence methanol fuel cells find their potential use in laptop chargers, military applications or other scenarios where the access to electricity is difficult.

However the wider spectrum of commercial potential for methanol systems is greatly hindered by methanol cross over occurring in the membrane area of fuel cells. This is defined as the passage of methanol from anode to the cathode through the membrane, hence creating short circuit and greatly affecting the fuel cell performance.

This is mitigated by using barrier layer, in addition to the membrane used. 

Figure 1: Schematic illustration of methanol fuel cell and structure of graphene

So far many materials have been used as a barrier layer in methanol fuel cells, where the proton conductivity is balanced with the methanol cross over. Proton conductivity is one of the dominant factors, where slight reduction in proton conductivity can influence the fuel cell performance to a large extent. All the materials reported in the literature to date have seen a reduction in proton conductivity though methanol cross over is reduced. 

It is known that Andre Geim and his co-workers (Nature, A.K. Geim et.al 2014), discovered proton transfer through single layer graphene and other 2D materials. Also graphene is known for its dense lattice packing structure, inhibiting the passage of methanol and other hydrocarbon based molecules across the membrane. However the actual application of these 2D materials in fuel cell systems has not yet been realized.

In this Advanced Energy Materials paper, the researchers have used single layer graphene and hBN, formed by chemical vapour deposition method, as a barrier layer in the membrane of methanol fuel cells. They have reported that this thinnest barrier layer ever used before shows negligible resistance to protons, at the same time reducing cross over, enhancing the cell performance by 50%. This is of significant interest, as this would lead to usage of 2D materials in fuel cells.

Based on the results of the research obtained, researchers have been granted EPSRC (Engineering and Physical Sciences Research council grant “Adventurers in Energy grant”) to pursue further research in this field. They have shown that as the surface coverage of the 2D material on the system improved, the performance improved.  This would lead to the usage of fuel cells, operating with high concentrated methanol fuels, as the current fuel cells suffer from cross over phenomena, with increased concentration. 

Moreover, this would pave the way for a membrane-less fuel cell system operating with higher efficiency. This technology could further be extended to other fuel cells types namely hydrogen fuel cells. Hydrogen fuel cells suffer from the usage of high cost humidifier, where the membrane needs to be humidified for improved proton conductivity. Whereas graphene, as reported in earlier studies, showed improved proton conductivity with temperature, without the need for humidifier systems. The future prospect could be realized in such a way that the fuel cells will make significant contribution to the future energy demand. 


Tags:  Fuel Cells  Graphene  hBN  Hexagonal boron nitride  Methane 

Share |
PermalinkComments (0)
 

What is the Best Form of Carbon Nanomaterial for Your Sporting Goods?

Posted By Dexter Johnson, The Graphene Council, Wednesday, November 16, 2016

Ever since nanomaterials made their first tentative steps into commercial markets, the early targets were in sporting goods. There is a pretty good catalogue of the different nanomaterials and the various sporting good products that they have been used for in a paper published in the Center for Knowledge Management of Nanoscience and Technology’s (CKMNT) from which an excerpt is provided here

The CKMNT report was compiled over three years ago and what is conspicuously absent from its list of nanomaterials for sporting goods is graphene. Carbon nanotubes are there as well as carbon nanofibers for bicycle frames—an application I had a brief foray into seven years ago when I tried to discern whether there was any appreciable benefit to using carbon nanofibers than just run-of-the-mill fillers in the composite.  But graphene just a few years back didn’t apparently make a blip on the radar.

That has all changed, of course, with graphene finding high-profile applications in tennis racquets and skis, both of which are produced by Head. However, I was more intrigued by the recent application of graphene in cycling since I am an avid cyclist myself.

The application that has gotten a lot of press is the adoption of graphene by venerable Italian cycling tire manufacturer Vittoria when it launched graphene-enabled tire dubbed G+ or Graphene Plus. You can see a promotional video below, but the main advantages of the graphene-enabled tires are supposed to be lighter weight, greater strength and durability. Of course, every tire is supposed to provide good grip and low rolling resistance and this new series of tires claims to tick those boxes as well.

My question was whether graphene could really offer much benefit over conventional reinforcing fillers like carbon black, or were we just looking at a bit of marketing and extra price per tire. So, I asked an industry expert in using graphene with different compounds, who asked to remain anonymous, if much benefit could be derived from using graphene in an application like this.

Vittoria has made it known that they are using a graphene platelet material for their tires. My source explained rubber compounding has so many variables that the kind of graphene platelet they are using would depend on the elastomer system, other parts of the filler system, protection system, process aids, curing package.

He added that as important as the specifications of the graphene are how they are processing the material is equally as important. Conventional reinforcing fillers such as carbon black are usually compounded into the raw rubber in mixers prior to vulcanization. Graphene, he explained, could be added into the product through a similar approach. However there are other routes to introducing graphene into the rubber matrix, which he was not at liberty to discuss.

The aims of modifying tire rubber formulations have traditionally been aimed at improving the so-called "tire triangle" of properties. This triad includes: Low rolling resistance, Abrasion resistance and Wet-traction control.

While graphene has been thought to improve these above properties, my source concedes that no matter what reinforcing fillers are used it is usually very difficult to obtain improvement to all three properties of the tire triangle simultaneously, there is usually a trade-off in performance between these properties. 

My source also points out that carbon nanotubes have long been expected to deliver the same type of improvements as graphene to tire performance but have never managed to gain a market foothold.

In the UK-based Cycling Weekly, the question of graphene in tires was given a lengthy discussion in which they interviewed one of Vittoria’s competitors, Continental.

“In the past we did some trials with graphene in the casing and tread of our tyres,” said Christian Wurmbäck, head of product development bicycle tires at Continental in the interview with Cycling Weekly. “However, although the directionality of the compound brought some benefits to the casing, the development of our Carbon Black compounds [which are said to use carbon nano particles] is at a higher level, so there was no need to jump back on graphene.”

It would seem the jury is still out on how much of a difference can make on improving your bicycle tires. I may just have to go and do a test, if I can get someone to send me a couple for testing purposes.

Tags:  bicycles  graphene  graphene platelets  sporting goods 

Share |
PermalinkComments (0)
 

Graphene used as toxic free MRI biomarker

Posted By Terrance Barkan, Saturday, November 12, 2016

This image from a high-resolution transmission electron microscope shows one of Rice University’s graphene-based MRI contrast agents, nanoparticles measuring about 10-nanometers in diameter that are so thin that they are difficult to distinguish. Credit: C.S. Tiwari/Rice University

Graphene, the atomically thin sheets of carbon that materials scientists are hoping to use for everything from nanoelectronics and aircraft de-icers to batteries and bone implants, may also find use as contrast agents for magnetic resonance imaging (MRI), according to new research from Rice University.

"They have a lot of advantages compared with conventionally available contrast agents," Rice researcher Sruthi Radhakrishnan said of the graphene-based quantum dots she has studied for the past two years. "Virtually all of the widely used contrast agents contain toxic metals, but our material has no metal. It's just carbon, hydrogen, oxygen and fluorine, and in all of our tests so far it has shown no signs of toxicity."

The initial findings for Rice's nanoparticles—disks of graphene that are decorated with fluorine atoms and simply organic molecules that make them magnetic—are described in a new paper in the journal Particle and Particle Systems Characterization.

Pulickel Ajayan, the Rice materials scientist who is directing the work, said the fluorinated graphene oxide quantum dots could be particularly useful as MRI contrast agents because they could be targeted to specific kinds of tissues.

"There are tried-and-true methods for attaching biomarkers to carbon nanoparticles, so one could easily envision using these quantum dots to develop tissue-specific contrast agents," Ajayan said. "For example, this method could be used to selectively target specific types of cancer or brain lesions caused by Alzheimer's disease. That kind of specificity isn't available with today's contrast agents."

Rice University graduate student Sruthi Radhakrishnan spent two years developing a process to make graphene-based quantum dots that could be used as MRI contrast agents. Credit: Jeff Fitlow/Rice University

MRI scanners make images of the body's internal structures using strong magnetic fields and radio waves. As diagnostic tests, MRIs often provide greater detail than X-rays without the harmful radiation, and as a result, MRI usage has risen sharply over the past decade. More than 30 million MRIs are performed annually in the U.S.


Radhakrishnan said her work began in 2014 after Ajayan's research team found that adding fluorine to either graphite or graphene caused the materials to show up well on MRI scans.
All materials are influenced by magnetic fields, including animal tissues. In MRI scanners, a powerful magnetic field causes individual atoms throughout the body to become magnetically aligned. A pulse of radio energy is used to disrupt this alignment, and the machine measures how long it takes for the atoms in different parts of the body to become realigned. Based on these measures, the scanner can build up a detailed image of the body's internal structures.

MRI contrast agents shorten the amount of time it takes for tissues to realign and significantly improve the resolution of MRI scans. Almost all commercially available contrast agents are made from toxic metals like gadolinium, iron or manganese.


"We worked with a team from MD Anderson Cancer Center to assess the cytocompatibility of fluorinated graphene oxide quantum dots," Radhakrishnan said. "We used a test that measures the metabolic activity of cell cultures and detects toxicity as a drop in metabolic activity. We incubated quantum dots in kidney cell cultures for up to three days and found no significant cell death in the cultures, even at the highest concentrations."

Unlike most currently used MRI contrast agents, Rice University’s fluorinated graphene oxide quantum dots contain no toxic metals and could potentially be targeted to specific kinds of tissues. Credit: Jeff Fitlow/Rice University

The fluorinated graphene oxide quantum dots Radhakrishnan studies can be made in less than a day, but she spent two years perfecting the recipe for them. She begins with micron-sized sheets of graphene that have been fluorinated and oxidized. When these are added to a solvent and stirred for several hours, they break into smaller pieces. Making the material smaller is not difficult, but the process for making small particles with the appropriate magnetic properties is exacting.

Radhakrishnan said there was no "eureka moment" in which she suddenly achieved the right results by stumbling on the best formula. Rather, the project was marked by incremental improvements through dozens of minor alterations.

"It required a lot of optimization," she said. "The recipe matters a lot."

Radhakrishnan said she plans to continue studying the material and hopes to eventually have a hand in proving that it is safe and effective for clinical MRI tests.
"I would like to see it applied commercially in clinical ways because it has a lot of advantages compared with conventionally available agents," she said.

 

Source: Phys.org

Tags:  contrast agents  GNP  magnetic resonance imaging  MD Anderson Cancer Center  MRI  Pulickel Ajayan  Rice University  Sruthi Radhakrishnan 

Share |
PermalinkComments (0)
 

New Properties Open Up New Applications for Graphene

Posted By Terrance Barkan, Friday, November 11, 2016

From properties as a superconductor to unexpected membrane separation abilities, graphene continues to surprise

 

When graphene is discovered to have new and sometimes unexpected properties, it quickly adds on potential new applications that it could be used for. 

 

This year we have seen that it actually does become a superconductor, opening up potential as material used in quantum computers. We have also seen graphene surprise even the Nobel Laureate who discovered it by it serving as a membrane for filtering out nuclear waste at nuclear power plants.

 

Graphene’s Potential as a Superconductor Just Got a Clearer

 


 

Illustration: Takashi Takahashi/Tohoku University

 

Graphene’s property as a conductor is unrivalled. The ballistic transport of graphene—the speed at which electrons pass through a material at room temperature—is so fast that it has surpassed what scientists believed were its theoretical limits. It is at the point now where electrons seem to be behaving like photons in graphene. Whenever this amazing property of graphene as a conductor is mentioned, people wonder if it might make for a good superconductor.

 

While there has been some research that has suggested that graphene could be made into a superconductor—a material with zero resistance to the flow of electricity—we now have more conclusive proof that it is indeed the case. 

 

In joint research out of Tohoku University and the University of Tokyo in Japan, scientists there have developed a new method for getting graphene to behave as a superconductor,  and in so doing have eliminated the chance that what they were observing was the transformation of graphene into a semiconductor.

 

Takashi Takahashi, a professor at Tohoku University and leader of the research, explained that they took a number of different approaches to ensure that what they were witnessing was graphene becoming a superconductor. In research published in the journal ACS Nano,  the researchers were first extremely meticulous about how they fabricated the graphene. 

 

They started with high-quality graphene on a silicon carbide crystal, and controlled the number of graphene sheets. This gave them a well-characterized bilayer graphene, into which they stuffed calcium atoms. So precise was the process hat they could actually ascribe a chemical formula to their sample: C6CaC6. This was an important achievement because having a precise count for the number of Li or Ca atoms determines the amount of donated electrons into graphene, which controls the occurrence of superconductivity.

 

The researchers’ measurements confirmed that superconductivity did occur with the graphene. Electrical resistivity dropped rapidly at around 4 K (-269 °C), indicative of an emergence of superconductivity. The measurements further indicated that the bilayer graphene did not create the superconductivity, nor did lithium-intercalated bilayer graphene exhibit superconductivity. This meant that the drop in resistance was due to the electron transfer from the calcium atoms to the graphene sheets.

 

Now that graphene has been made to perform as a superconductor with a clear zero electrical resistivity, it becomes possible to start considering applying graphene into the making of a quantum computer that would use this superconducting graphene as the basis for an integrated circuit.

 

Unfortunately, like most superconducting materials, the temperature at which graphene reaches superconductivity is too low to be practical. Raising that temperature will be the next step in the research. 

 

Graphene Nanoribbons Increase Their Potential

 


Image: Patrick Han

 

Graphene nanoribbons (GNRs) appear to be among the best options for electronics applications because of the each with which it’s possible to engineer a band gap into them. Narrow ones are semiconductors, while wider ones act as conductors. Pretty simple.

 

With improved methods being developed for manufacturing GNRs that are both compatible with current semiconductor manufacturing methods and can be scaled up, the future would appear bright. But there’s not a lot of knowledge of what happens when you start trying to manipulate GNRs into actual electronic devices.

 

Now a team of researchers at Tohoku University's Advanced Institute of Materials Research (AIMR) in Japan is investigating what happens when you interconnect GNRs end to end using molecular assembly to form elbow structures, which are essentially interconnection points.  The researchers believe that this development provides the key to unlocking GNRs’ potential in high-performance and low-power-consumption electronics.

 

“Current molecular assemblies either produce straight GNRs (i.e., without identifiable interconnection points), or randomly interconnected GNRs,” said Dr. Patrick Han, the project leader, in press release. “These growth modes have too many intrinsic unknowns for determining whether electrons travel across graphene interconnection points smoothly,” said Han, who added that, “The key is to design a molecular assembly that produces GNRs that are systematically interconnected with clearly distinguishable interconnection points.”

 

In research published in the journal ACS Nano, the AIMR researchers demonstrated that both the electron and thermal conductivities of two interconnected GNRs should be the same as that of the ends of a single GNR.

 

“The major finding of this work is that interconnected GNRs do not show electronic disruption (e.g., electron localization that increases resistance at the interconnection points),” said Han in the press release. “The electronically smooth interconnection demonstrates that GNR properties (including tailored band gaps, or even spin-aligned zigzag edges) can be connected to other graphene structures. These results show that finding a way to connect defect-free GNRs to desired electrodes may be the key strategy toward achieving high-performance, low-power-consumption electronics.”

 

Graphene Has Special Properties for Cleaning Up Nuclear Waste

 


Image: The University of Manchester

 

The merits of graphene as a separation membrane medium have long been extolled.  The properties that distinguish graphene for these applications are its large surface area, the variability of its pore size and its adhesion properties.

 

These attractive properties have not gone unnoticed by Andre Geim, who, along with Konstantin Novoselov, won the 2010 Nobel Prize in Physics for their discovery and study of graphene. Geim has dedicated a significant amount of his research efforts since then to the use of graphene as a filtering medium in various separation technologies.

 

Now Geim and his colleagues at the University of Manchester have found that graphene filters are effective at cleaning up the nuclear waste produced at nuclear power plants.   This application could make one of the most costly and complicated aspects of nuclear power generation ten times less energy intensive and therefore much more cost effective.

 

In research published in the journal Science, Geim and his colleagues at Manchester experimented to see if the nuclei of deuterium—deuterons—could pass through the two-dimensional (2-D) materials graphene and boron nitride. The existing theories seemed to suggest that the deuterons would pass through easily. But to the surprise of the researchers, not only did the 2-D membranes sieve out the deuterons, but the separation was also accomplished with a high degree of efficiency.

 

“This is really the first membrane shown to distinguish between subatomic particles, all at room temperature,” said Marcelo Lozada-Hidalgo, a post-doctoral researcher at the University of Manchester and first author of the paper, in a press release. “Now that we showed that it is a fully scalable technology, we hope it will quickly find its way to real applications.”

 

Irina Grigorieva, another member of the research team, added: “It is a really simple set up. We hope to see applications of these filters not only in analytical and chemical tracing technologies but also in helping to clean nuclear waste from radioactive tritium.”

Tags:  Andre Geim  ballistic transport  Irina Grigorieva  Konstantin Novoselov  Marcelo Lozada-Hidalgo  University of Manchester 

Share |
PermalinkComments (0)
 

Graphene Certification Needed

Posted By Terrance Barkan, Wednesday, November 9, 2016

One of the major problems identified in our survey of the global graphene community was the lack of agreed standards for graphene materials.

In addition, there is a tremendous lack of transparency into the actual quality and characteristics of material that is being produced and sold as "graphene".

Survey respondents reported that batches of graphene were often inconsistent (even from the same producer) or were not material that could seriously be considered graphene. (More like micro-graphite). 


This is not only a problem for customers, researchers and users of purchased materials, it is a problem for legitimate graphene producers to differentiate themselves from companies that claim to be selling graphene but that are instead producing some other forms of carbon containing materials. 

The lack of an agreed global standard for graphene and closely related materials creates a vacuum and lack of trust in the marketplace for industrial scale adoption of graphene materials. This is true even though forms of graphene and reduced graphene oxide have proven to provide outstanding performance improvements in composites, inks and 3D filaments to name but a few examples. 

I would like to hear from you if you agree with this view and if you feel that the establishment of a regime to certify the quality / characteristics of commercially available graphene products is a good idea. 

Feel free to post a reply or send me a private message directly at: 
tbarkan@thegrapheneconcil.org

You can also see the original postings in our LinkedIn group at: 
http://www.linkedin.com/groups/Graphene-Council-5153830/about

Tags:  Certification  Developers  Graphene  Producers  Standards  Survey  Testing  Users 

Share |
PermalinkComments (0)
 

Graphene is leading to ultrafast wireless communication

Posted By Terrance Barkan, Wednesday, November 2, 2016


Graphene-based nanoantennas (blue and red dots) on a chip. Credit: University at Buffalo

For wireless communication, we’re all stuck on the same traffic-clogged highway — it’s a section of the electromagnetic spectrum known as radio waves.

Advancements have made the highway more efficient, but bandwidth issues persist as wireless devices proliferate and the demand for data grows. The solution may be a nearby, mostly untapped area of the electromagnetic spectrum known as the terahertz band.

“For wireless communication, the terahertz band is like an express lane. But there’s a problem: there are no entrance ramps,” says Josep Jornet, PhD, assistant professor in the Department of Electrical Engineering at the University at Buffalo School of Engineering and Applied Sciences.

Jornet is the principal investigator of a three-year, $624,497 grant from the U.S. Air Force Office of Scientific Research to help develop a wireless communication network in the terahertz band. Co-principal investigators are Jonathan Bird, PhD, professor of electrical engineering, and Erik Einarsson, PhD, assistant professor of electrical engineering, both at UB.

Their work centers on developing extremely small radios — made of graphene and semiconducting materials — that enable short-range, high-speed communication.

The technology could ultimately reduce the time it takes to complete complex tasks, such as migrating the files of one computer to another, from hours to seconds. Other potential applications include implantable body nanosensors that monitor sick or at-risk people, and nanosensors placed on aging bridges, in polluted waterways and other public locations to provide ultra-high-definition streaming.

These are examples of the so-called Internet of Nano-Things, a play on the more common Internet of Things, in which everyday objects are hooked up to the cloud via sensors, microprocessors and other technology.

“We’ll be able to create highly accurate, detailed and timely maps of what’s happening within a given system. The technology has applications in health care, agriculture, energy efficiency — basically anything you want more data on,” Jornet says.

The untapped potential of Terahertz waves

Sandwiched between radio waves (part of the electromagnetic spectrum that includes AM radio, radar and smartphones) and light waves (remote controls, fiber optic cables and more), the terahertz spectrum is seldom used by comparison.

Graphene-based radios could help overcome a problem with terahertz waves: they do not retain their power density over long distances. It’s an idea that Jornet began studying in 2009 as a graduate student at Georgia Tech under Ian Akyildiz, PhD, Ken Byers Chair Professor in Telecommunications.

Graphene is a two-dimensional sheet of carbon that, in addition to being incredibly strong, thin and light, has tantalizing electronic properties. For example, electrons move 50 to 500 times faster in graphene compared to silicon.

In previous studies, researchers showed that tiny antennas graphene strips 10-100 nanometers wide and one micrometer long, combined with semiconducting materials such as indium gallium arsenide — can transmit and receive terahertz waves at wireless speeds greater than one terabit per second.

But to make these radios viable outside the laboratory, the antennas need other electronic components, such as generators and detectors that work in the same environment. This is the work that Jornet and his colleagues are focusing on.

Jornet says thousands — perhaps millions — of these arrayed radios working together could allow terahertz waves to travel greater distances. The nanosenors could be embedded into physical objects, such as walls and street signs, as well as chips and other electronic components, to create an Internet of Nano-Things.

“The possibilities are limitless,” says Jornet.

Jornet is a member of the Signals, Communications and Networks research group at UB’s electrical engineering department, while Bird and Einarsson work in the department’s Solid State Electronics research group.

The work described above is an example of the department’s strategy to hire faculty members with complimentary expertise that drive the convergence of basic research areas while developing new technologies and educating students.

Source: Cory Nealon

Tags:  Graphene  Internet of Things  Josep Jornet  Nanosensors  Radio  U.S. Air Force Office of Scientific Research  University at Buffalo  Wireless 

Share |
PermalinkComments (0)
 

MIT's Michael Strano turns plants into chemical detectors

Posted By Terrance Barkan, Monday, October 31, 2016

Scientists have transformed the humble spinach plant into a bomb detector.

Source: MIT

By embedding tiny tubes in the plants' leaves, they can be made to pick up chemicals called nitro-aromatics, which are found in landmines and buried munitions. Real-time information can then be wirelessly relayed to a handheld device.

The MIT (Massachusetts Institute of Technology) work is published in the journal Nature Materials. The scientists implanted nanoparticles and carbon nanotubes (tiny cylinders of carbon) into the leaves of the spinach plant. It takes about 10 minutes for the spinach to take up the water into the leaves.

To read the signal, the researchers shine a laser onto the leaf, prompting the embedded nanotubes to emit near-infrared fluorescent light. This can be detected with a small infrared camera connected to a small, cheap Raspberry Pi computer. The signal can also be detected with a smartphone by removing the infrared filter most have.

Co-author Prof Michael Strano, from MIT in Cambridge, US, said the work was an important proof of principle. "Our paper outlines how one could engineer plants like this to detect virtually anything," he told the BBC News website.

Prof Strano's lab has previously developed carbon nanotubes that can be used as sensors to detect hydrogen peroxide, TNT, and the nerve gas sarin. When the target molecule binds to a polymer material wrapped around the nanotube, it changes the way it glows. "The plants could be use for defence applications, but also to monitor public spaces for terrorism related activities, since we show both water and airborne detection," said Prof Strano.

"Such plants could be used to monitor groundwater seepage from buried munitions or waste that contains nitro-aromatics." Using the set-up described in the paper, the researchers can pick up a signal from about 1m away from the plant, and they are now working on increasing that distance.

Source: BBC News

Tags:  Carbon Nanotubes  Michael Strano  MIT  Sensors 

Share |
PermalinkComments (0)
 

Electronics Applications for Graphene Hold Great Promise

Posted By Terrance Barkan, Monday, October 31, 2016

Applications that have really spurred a huge amount of graphene and other two-dimensional (2D) material research over the years have come from the field of electronics. The fear that complementary metal–oxide–semiconductor (CMOS) technology is quickly nearing the end of its ability to ward off Moore’s Law, in which the number of transistors in a dense integrated circuit doubles approximately every two years, has been the spur for much graphene research.

However, there has always been the big problem for graphene that it does not have an intrinsic band gap. It’s a pure conductor and not a semiconductor, like silicon, capable turning on and off the flow of electrons through it. While graphene can be functionalized in a way that it does have a band gap, research for it in the field of electronics have looked outside of digital logic where an intrinsic band gap is such an advantage. 

In the stories below, we see how graphene’s unrivaled conductivity is being exploited to take advantage of its strengths rather than trying to cover up for its weaknesses.

Graphene Comes to the Rescue of Li-ion Batteries

The role of graphene in increasing the charge capacity of the electrodes in lithium-ion (Li-ion) batteries has varied. There’s been “decorated graphene” in which nanoparticles are scattered across the surface of the graphene, and graphene nanoribbons, just to name a few of the avenues that have been pursued.

Another way in which graphene has been looked at is to better enable silicon to serve as the electrode material for Li-ion batteries. Silicon is a great material for increasing the storage capacity of electrodes in Li-ion batteries, but there’s one big problem: it cracks after just few charge/discharge cycles. The aim has been to find a way to make silicon so that it’s not so brittle and can withstand the swelling and shrinking during the charge charging and discharing of lithium atoms into the electrode material In these efforts, like those out Northwestern University, the role of graphene has been to sandwich silicon between layers graphene sheets in the anode of the battery.

Now, Yi Cui from both Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory, who has been at the forefront of research to get silicon to be more flexible and durable for Li-ion batteries, has turned to graphene to solve the issue

Cui and his colleagues were able to demonstrate in research described in the journal Nature Energy, a method for to encasing each particle of silicon in a cage of graphene that enables the silicon to expand and contract without cracking. In a full-cell electrochemical test, the graphene-infused silicon anodes retained 90 percent of their charge capacity after 100 charge-discharge cycles. 

Previous attempts by Cui and many others to create nanostructured silicon has been very difficult, making mass production fairly impractical. However, based on these latest results, Cui believes that this approach is not only technologically possible, but may in fact be commercially viable.

The process involves coating the silicon particles with a layer of nickel. The nickel coating is used as the surface and the catalyst for the second step: growing the graphene. The final step of the process involves using an acid on the graphene-coated silicon particles so that the nickel is etched away.

“This new method allows us to use much larger silicon particles that are one to three microns, or millionths of a meter, in diameter, which are cheap and widely available,” Cui said in a press release. “Particles this big have never performed well in battery anodes before, so this is a very exciting new achievement, and we think it offers a practical solution.”

While a practical manufacturing approach was much needed, the technique also leads to an electrode material with very high charge capacity.

“Researchers have tried a number of other coatings for silicon anodes, but they all reduced the anode’s efficiency,” said Stanford postdoctoral researcher Kai Yan, in a press release. “The form-fitting graphene cages are the first coating that maintains high efficiency, and the reactions can be carried out at relatively low temperatures.”

Graphene Provides the Perfect Touch to Flexible Sensors

 

Photo: Someya Laboratory

Flexible sensors are the technological backbone of artificial skin technologies. The idea is that you can impart the sense of touch to a flexible sensor, making it possible to cover a prosthetic device for either a robot or replacement limb so it can feel. Creating materials that tick the boxes of flexibility, durability and sensitivity has been a challenge. Over the years, researchers have increasingly turned to nanomaterials, and graphene in particular, as a possible solution. 

Researchers at the University of Tokyo have found that nanofibers produced from a combination of carbon nanotubes and graphene overcomes some of the big problems facing flexible pressure sensors: they’re not that accurate after being bent or deformed. The researchers have suggested that the flexible sensor they have developed could provide a more accurate detection breast cancer.

In research described in the journal Nature Nanotechnology, the scientists produced their flexible sensor by employing organic transistors and a pressure sensitive nanofiber structure.

The researchers constructed the nanofiber structure using nanofibers with diameters ranging between 300 to 700 nanometers. The researchers produced the nanofibers by combining carbon nanotubes and graphene and mixing that into a flexible polymer. The nanofibers entangled with each other to form a thin, transparent structure.

In contrast to other flexible sensors in which the striving for accuracy makes the sensors too sensitive to being deformed in any way, the fibers in this new flexible sensor does not lose their accuracy in measuring pressures. These fibers achieve this because of their ability to change their relative alignment to accommodate the bending. This allows them to continue measuring pressure because it reduces the strain in individual fibers.

Tunable Graphene Plasmons Lead to Tunable Lasers

Illustration: University of Manchester

A few years ago, researchers found that the phenomenon that occurs when photons strike a metallic surface and stir up the movement of electrons on the surface to the point where the electrons form into waves—known as surface plasmons—also occurs in graphene. 

This discovery along with the ability to tune the graphene plasmons has been a big boon for the use of graphene in optoelectronic applications.  Now research out of the University of Manchester, led by Konstantin Novoselov, who along with Andre Geim were the two University of Manchester scientists who won the Nobel Prize for discovering graphene, has leveraged the ability of tuning graphene plasmons and combined it with terahertz quantum cascade lasers, making it possible to reversibly alter their emission. 

This ability to reversibly the alter the emission of quantum cascade lasers is a big deal in optoelectronic applicatiopns, such as fiber optics telecommunication technologies by offering potentially higher bandwidth capabilities.

“Current terahertz devices do not allow for tunable properties, a new device would have to be made each time requirements changed, making them unattractive on an industrial scale,” said Novoselov in a press release. “Graphene however, can allow for terahertz devices to be switched on and off, as well as altering their state.”

In research described in the journal Science, were able to manipulate the doping levels of a graphene sheet so that it generated plasmons on its surface. When this doped graphene sheet was combined with a terahertz quantum cascade laser, it became possible to tune the transmission of the laser by tuning the graphene plasmons, essentially changing the concentration of charge carriers.

Graphene Flakes Speed Up Artificial Brains

Illustration: Alexey Kotelnikov/Alamy


Researchers out of Princeton University have found that graphene flakes could be a key feature in computer chips that aim at mimicking the function of the human brain. 


In the human brain, neurons are used to transmit information by passing electrical charges through them. In artificial brains, transistors would take the place of neurons. One approach has been to construct the transistors out of lasers that would turn and off and the time intervals between the on and off states of the lasers would represent the 1s and 0s of digital logic.

One of the challenges that researchers have faced in this design is getting the time intervals between the laser pulses down to picosecond time scales, one trillionth of a second.

In research described in the journal Nature Scientific Reports, the Princeton researchers placed graphene flakes inside a semiconductor laser to act as a kind of “saturable absorber,” that absorbed photons and then was able to emit them in a quick burst. 

It turns out graphene possesses a number of properties that makes it attractive for this application. Not only can it absorb and release photons extremely quickly, but it can also work at any wavelength. What this means is that even if semiconductor lasers are emitting different colors, the graphene makes it possible for them to work together simultaneously without interfering with each other, leading to higher processing speeds.

 

 

 

 

 

Tags:  Batteries  Decorated Graphene  Electronics  Flexible Sensors  Graphene  Graphene Nanoribbons  Lasers  Li-ion  optoelectronics  Semiconductor 

Share |
PermalinkComments (0)
 
Page 69 of 70
 |<   <<   <  64  |  65  |  66  |  67  |  68  |  69  |  70