One of the issues with new materials is being able to produce them in a commercially viable fashion and it seems that researchers in Australia may have helped to do that with graphene. From a Feb. 15, 2017 news item on phys.org,
A breakthrough by CSIRO-led [Australia’s Commonwealth Scientific and Industrial Research Organisation] scientists has made the world’s strongest material more commercially viable, thanks to the humble soybean.
Graphene is a carbon material that is one atom thick.
Its thin composition and high conductivity means it is used in applications ranging from miniaturised electronics to biomedical devices.
These properties also enable thinner wire connections; providing extensive benefits for computers, solar panels, batteries, sensors and other devices.
Until now, the high cost of graphene production has been the major roadblock in its commercialisation.
Previously, graphene was grown in a highly-controlled environment with explosive compressed gases, requiring long hours of operation at high temperatures and extensive vacuum processing.
CSIRO scientists have developed a novel “GraphAir” technology which eliminates the need for such a highly-controlled environment.
The technology grows graphene film in ambient air with a natural precursor, making its production faster and simpler.
“This ambient-air process for graphene fabrication is fast, simple, safe, potentially scalable, and integration-friendly,” CSIRO scientist Dr Zhao Jun Han, co-author of the paper published today in Nature Communications said.
“Our unique technology is expected to reduce the cost of graphene production and improve the uptake in new applications.”
GraphAir transforms soybean oil – a renewable, natural material – into graphene films in a single step.
“Our GraphAir technology results in good and transformable graphene properties, comparable to graphene made by conventional methods,” CSIRO scientist and co-author of the study Dr Dong Han Seo said.
With heat, soybean oil breaks down into a range of carbon building units that are essential for the synthesis of graphene.
The team also transformed other types of renewable and even waste oil, such as those leftover from barbecues or cooking, into graphene films.
“We can now recycle waste oils that would have otherwise been discarded and transform them into something useful,” Dr Seo said.
The potential applications of graphene include water filtration and purification, renewable energy, sensors, personalised healthcare and medicine, to name a few.
Graphene has excellent electronic, mechanical, thermal and optical properties as well.
Its uses range from improving battery performance in energy devices, to cheaper solar panels.
CSIRO are looking to partner with industry to find new uses for graphene.
Researchers from The University of Sydney, University of Technology Sydney and The Queensland University of Technology also contributed to this work.
A Feb. 8, 2017 news item on phys.org features a ‘dream’ diode from Ulsan National Institute of Science and Technology,
A team of researchers, affiliated with UNIST [Ulsan National Institute of Science and Technology] has created a new technique that greatly enhances the performance of Schottky Diodes (metal-semiconductor junction) used in electronic devices. Their research findings have attracted considerable attention within the scientific community by solving the contact resistance problem of metal-semiconductor, which had remained unsolved for almost 50 years.
As described in the January  issue of Nano Letters, the researchers have created a new type of diode with a graphene insertion layer sandwiched between metal and semiconductor. This new technique blows all previous attemps out the water, as it is expected to significantly contribute to the semiconductor industry’s growth.
The Schottky diode is one of the oldest and most representative semiconductor devices, formed by the junction of a semiconductor with a metal. However, due to the atomic intermixing along the interface between two materials, it has been impossible to produce an ideal diode. (An ideal diode acts like a perfect conductor when voltage is applied forward biased and like a perfect insulator when voltage is applied reverse biased.)
The schematic view of internal photoemission (IPE) measurements on metal/n-Si(001) junctions with Ni, Pt, and Ti electrodes for with and without a graphene insertion layer.
Professor Kibog Park of Natural Science solved this problem by inserting a graphene layer at the metal-semiconductor interface. In the study, the research team demonstrated that this graphene layer, consisting of a single layer of carbon atoms can not only suppress the material intermixing substantially, but also matches well with the theoretical prediction.
“The sheets of graphene in graphite have a space between each sheet that shows a high electron density of quantum mechanics in that no atoms can pass through,” says Professor Park. “Therefore, with this single-layer graphene sandwiched between metal and semiconductor, it is possible to overcome the inevitable atomic diffusion problem.”
The study also has the physiological meaning of confirming the theoretical prediction that “In the case of silicon semiconductors, the electrical properties of the junction surfaces hardly change regardless of the type of metal they use,” according to Hoon Hahn Yoon (Combined M.S./Ph.D. student of Natural Science), the first author of the study.
The internal photoemission method was used to measure the electronic energy barrier of the newly-fabricated metal/graphene/n-Si(001) junction diodes. The Internal Photoemission (IPE) Measurement System in the image shown above has contributed greatly to these experiments. This system has been developed by four UNIST graduate students (Hoon Han Yoon, Sungchul Jung, Gahyun Choi, and Junhyung Kim), which was carried out as part of an undergraduate research project in 2012 and was supported by the Korea Foundation for the Advancement of Science and Creativity (KOFAC).
Shown above is the Internal Photoemission (IPE) Measurement System, developed by Hoon Hahn Yoon, combined M.S./Ph.D. student of Natural Science at UNIST.
“Students have teamed up and carried out all the necessary steps for the research since they were undergraduates,” Professor Park says. “Therefore, this research is a perfect example of time, persistence, and patience paying off.”
This study has been jointly conducted by Professor Hu Young Jeong of the UNIST Central Research Facilities (UCRF), Professor Kwanpyo Kim of Natural Science, Professor Soon-Yong Kwon of Materials Science and Engineering, and Professor Yong Soo Kim of Ulsan University. It has been also supported by the National Research Foundation of Korea, Nuclear Research Basis Expansion Project, as well as the Global Ph.D Fellowship (GPF).
Even I can tell the image is improved when the chelator is omitted,
A Feb. 9, 2017 news item on phys.org describes a new, chelator-free technique for increased bioimaging accuracy,
Positron emission tomography (PET) plays a pivotal role for monitoring the distribution and accumulation of radiolabeled nanomaterials in living subjects. The radioactive metals are usually connected to the nanomaterial through an anchor, a so-called chelator, but this chemical binding can be omitted if nanographene is used, as American scientists report in the journal Angewandte Chemie. The replacement of chelator-based labeling by intrinsic labeling significantly enhances the bioimaging accuracy and reduces biases.
Nanoparticles are very promising substances for biodiagnostics (e.g., detecting cancerous tissue) and biotherapy (e.g., destroying tumors by molecular agents), because they are not as fast [sic] metabolized as normal pharmaceuticals and they particularly enrich [sic] in tumors through an effect called enhanced permeability and retention (EPR). Chelators, which have a macrocyclic structure, are used to anchor the radioactive element (e.g., copper-64) onto the nanoparticles’ surface. The tracers are then detected and localized in the body with the help of a positron emission tomography (PET) scanner. However, the use of a chelator can also be problematic, because it can detach from the nanoparticles or bias the imaging. Therefore, the group of Weibo Cai at University of Wisconsin-Madison, USA, sought for chelator-free solutions—and found it in nanographene, one of the most promising substances in nanotechnology.
Nanographene offers the electronic system to provide special binding electrons for some transition metal ions. “π bonds of nanographene are able to provide the additional electron to stably incorporate the 64Cu2+ acceptor ions onto the surface of graphene,” the authors wrote. Thus, it was possible to directly and stably attach the copper isotope to reduced graphene oxide nanomaterials stabilized by poly(ethylene glycol) (PEG), and this system was used for several bioimaging tests including the detection of tumors in mice.
After injection in the mouse model, the scientists observed long blood circulation and high tumor uptake. “Prolonged blood circulation of 64Cu-RGO-PEG […] induced a prompt and persistent tumor uptake via EPR effect,” they wrote. Moreover, the directly radiolabeled nanographene was readily prepared by simply mixing both components and heating them. This simple chelator-free, intrinsically labeled system may provide an attractive alternative to the chelator-based radiolabeling, which is still the “gold standard” in bioimaging.
Here’s a link to and a citation for the paper,
Chelator-Free Radiolabeling of Nanographene: Breaking the Stereotype of Chelation by Sixiang Shi, Cheng Xu, Dr. Kai Yang, Shreya Goel, Hector F. Valdovinos, Dr. Haiming Luo, Emily B. Ehlerding, Dr. Christopher G. England, Dr. Liang Cheng, Dr. Feng Chen, Prof. Robert J. Nickles, Prof. Zhuang Liu, and Prof. Weibo Cai. Angewandte Chemie International Edition DOI: 10.1002/anie.201610649 Version of Record online: 7 FEB 2017
A Feb. 3, 2017 news item on Nanowerk announces research that could help us better understand how stars are ‘born’,
Graphene is known as the world’s thinnest material due to its 2D structure, where each sheet is only one carbon atom thick, allowing each atom to engage in a chemical reaction from two sides. Graphene flakes can have a very large proportion of edge atoms, all of which have a particular chemical reactivity.
In addition, chemically active voids created by missing atoms are a surface defect of graphene sheets. These structural defects and edges play a vital role in carbon chemistry and physics, as they alter the chemical reactivity of graphene. In fact, chemical reactions have repeatedly been shown to be favoured at these defect sites.
Interstellar molecular clouds are predominantly composed of hydrogen in molecular form (H2), but also contain a small percentage of dust particles mostly in the form of carbon nanostructures, called polyaromatic hydrocarbons (PAH). These clouds are often referred to as ‘star nurseries’ as their low temperature and high density allows gravity to locally condense matter in such a way that it initiates H fusion, the nuclear reaction at the heart of each star.
Graphene-based materials, prepared from the exfoliation of graphite oxide, are used as a model of interstellar carbon dust as they contain a relatively large amount of atomic defects, either at their edges or on their surface. These defects are thought to sustain the Eley-Rideal chemical reaction, which recombines two H atoms into one H2 molecule. The observation of interstellar clouds in inhospitable regions of space, including in the direct proximity of giant stars, poses the question of the origin of the stability of hydrogen in the molecular form (H2).
This question stands because the clouds are constantly being washed out by intense radiation, hence cracking the hydrogen molecules into atoms. Astrochemists suggest that the chemical mechanism responsible for the recombination of atomic H into molecular H2 is catalysed by carbon flakes in interstellar clouds.
Their [astrochemists’s] theories are challenged by the need for a very efficient surface chemistry scenario to explain the observed equilibrium between dissociation and recombination. They had to introduce highly reactive sites into their models so that the capture of an atomic H nearby occurs without fail. These sites, in the form of atomic defects at the surface or edge of the carbon flakes, should be such that the C-H bond formed thereafter allows the H atom to be released easily to recombine with another H atom flying nearby.
A collaboration between the Institut Laue-Langevin (ILL), France, the University of Parma, Italy, and the ISIS Neutron and Muon Source, UK, combined neutron spectroscopy with density functional theory (DFT) molecular dynamics simulations in order to characterise the local environment and vibrations of hydrogen atoms chemically bonded at the surface of substantially defected graphene flakes. Additional analyses were carried out using muon spectroscopy (muSR) and nuclear magnetic resonance (NMR). As availability of the samples is very low, these highly specific techniques were necessary to study the samples; neutron spectroscopy is highly sensitive to hydrogen and allowed accurate data to be gathered at small concentrations.
For the first time ever, this study showed ‘quantum tunnelling’ in these systems, allowing the H atoms bound to C atoms to explore relatively long distances at temperatures as low as those in interstitial clouds. The process involves hydrogen ‘quantum hopping’ from one carbon atom to another in its direct vicinity, tunnelling through energy barriers which could not be overcome given the lack of heat in the interstellar cloud environment. This movement is sustained by the fluctuations of the graphene structure, which bring the H atom into unstable regions and catalyse the recombination process by allowing the release of the chemically bonded H atom. Therefore, it is believed that quantum tunnelling facilitates the reaction for the formation of molecular H2.
ILL scientist and carbon nanostructure specialist, Stéphane Rols says: “The question of how molecular hydrogen forms at the low temperatures in interstellar clouds has always been a driver in astrochemistry research. We’re proud to have combined spectroscopy expertise with the sensitivity of neutrons to identify the intriguing quantum tunnelling phenomenon as a possible mechanism behind the formation of H2; these observations are significant in furthering our understanding of the universe.”
Here’s a link to and a citation for the paper (which dates from Aug. 2016),
Hydrogen motions in defective graphene: the role of surface defects by Chiara Cavallari, Daniele Pontiroli, Mónica Jiménez-Ruiz, Mark Johnson, Matteo Aramini, Mattia Gaboardi, Stewart F. Parker, Mauro Riccó, and Stéphane Rols. Phys. Chem. Chem. Phys., 2016, Issue 36, 18, 24820-24824 DOI: 10.1039/C6CP04727K First published online 22 Aug 2016
I’ve been hearing about Mildred Dresselhaus, professor emerita (retired professor) at the Massachusetts Institute of Technology (MIT), just about as long as I’ve been researching and writing about nanotechnology (about 10 years including the work for my master’s project with the almost eight years on this blog).
She died on Monday, Feb. 20, 2017 at the age of 86 having broken through barriers for those of her gender, barriers for her subject area, and barriers for her age.
Mark Anderson in his Feb. 22, 2017 obituary for the IEEE (Institute of Electrical and Electronics Engineers) Spectrum website provides a brief overview of her extraordinary life and accomplishments,
Called the “Queen of Carbon Science,” Dresselhaus pioneered the study of carbon nanostructures at a time when studying physical and material properties of commonplace atoms like carbon was out of favor. Her visionary perspectives on the sixth atom in the periodic table—including exploring individual layers of carbon atoms (precursors to graphene), developing carbon fibers stronger than steel, and revealing new carbon structures that were ultimately developed into buckyballs and nanotubes—invigorated the field.
“Millie Dresselhaus began life as the child of poor Polish immigrants in the Bronx; by the end, she was Institute Professor Emerita, the highest distinction awarded by the MIT faculty. A physicist, materials scientist, and electrical engineer, she was known as the ‘Queen of Carbon’ because her work paved the way for much of today’s carbon-based nanotechnology,” MIT president Rafael Reif said in a prepared statement.
Friends and colleagues describe Dresselhaus as a gifted instructor as well as a tireless and inspired researcher. And her boundless generosity toward colleagues, students, and girls and women pursuing careers in science is legendary.
In 1963, Dresselhaus began her own career studying carbon by publishing a paper on graphite in the IBM Journal for Research and Development, a foundational work in the history of nanotechnology. To this day, her studies of the electronic structure of this material serve as a reference point for explorations of the electronic structure of fullerenes and carbon nanotubes. Coauthor, with her husband Gene Dresselhaus, of a leading book on carbon fibers, she began studying the laser vaporation of carbon and the “carbon clusters” that resulted. Researchers who followed her lead discovered a 60-carbon structure that was soon identified as the icosahedral “soccer ball” molecular configuration known as buckminsterfullerene, or buckyball. In 1991, Dresselhaus further suggested that fullerene could be elongated as a tube, and she outlined these imagined objects’ symmetries. Not long after, researchers announced the discovery of carbon nanotubes.
When she began her nearly half-century career at MIT, as a visiting professor, women consisted of just 4 percent of the undergraduate student population. So Dresselhaus began working toward the improvement of living conditions for women students at the university. Through her leadership, MIT adopted an equal and joint admission process for women and men. (Previously, MIT had propounded the self-fulfilling prophecy of harboring more stringent requirements for women based on less dormitory space and perceived poorer performance.) And so promoting women in STEM—before it was ever called STEM—became one of her passions. Serving as president of the American Physical Society, she spearheaded and launched initiatives like the Committee on the Status of Women in Physics and the society’s more informal committees of visiting women physicists on campuses around the United States, which have increased the female faculty and student populations on the campuses they visit.
If you have the time, please read Anderson’s piece in its entirety.
One fact that has impressed me greatly is that Dresselhaus kept working into her eighties. I featured a paper she published in an April 27, 2012 posting at the age of 82 and she was described in the MIT write up at the time as a professor, not a professor emerita. I later featured Dresselhaus in a May 31, 2012 posting when she was awarded the Kavli Prize for Nanoscience.
It seems she worked almost to the end. Recently, GE (General Electric) posted a video “What If Scientists Were Celebrities?” starring Mildred Dresselhaus,
H/t Mark Anderson’s obituary Feb. 22, 2017 piece. The video was posted on Feb. 8, 2017.
Physicists at Kansas State University use controlled detonation to make graphene according to a Jan. 25, 2017 news item on Nanowerk (Note: A link has been removed),
Forget chemicals, catalysts and expensive machinery — a Kansas State University team of physicists has discovered a way to mass-produce graphene with three ingredients: hydrocarbon gas, oxygen and a spark plug.
Their method is simple: Fill a chamber with acetylene or ethylene gas and oxygen. Use a vehicle spark plug to create a contained detonation. Collect the graphene that forms afterward.
Chris Sorensen, Cortelyou-Rust university distinguished professor of physics, is the lead inventor of the recently issued patent, “Process for high-yield production of graphene via detonation of carbon-containing material”. Other Kansas State University researchers involved include Arjun Nepal, postdoctoral researcher and instructor of physics, and Gajendra Prasad Singh, former visiting scientist.
“We have discovered a viable process to make graphene,” Sorensen said. “Our process has many positive properties, from the economic feasibility, the possibility for large-scale production and the lack of nasty chemicals. What might be the best property of all is that the energy required to make a gram of graphene through our process is much less than other processes because all it takes is a single spark.”
Graphene is a single atom-thick sheet of hexagonally coordinated carbon atoms, which makes it the world’s thinnest material. Since graphene was isolated in 2004, scientists have found it has valuable physical and electronic properties with many possible applications, such as more efficient rechargeable batteries or better electronics.
For Sorensen’s research team, the serendipitous path to creating graphene started when they were developing and patenting carbon soot aerosol gels. They created the gels by filling a 17-liter aluminum chamber with acetylene gas and oxygen. Using a spark plug, they created a detonation in the chamber. The soot from the detonation formed aerosol gels that looked like “black angel food cake,” Sorensen said.
But after further analysis, the researchers found that the aerosol gel was more than lookalike dark angel food cake — it was graphene.
“We made graphene by serendipity,” Sorensen said. “We didn’t plan on making graphene. We planned on making the aerosol gel and we got lucky.”
But unlike other methods of creating graphene, Sorensen’s method is simple, efficient, low-cost and scalable for industry.
Other methods of creating graphene involve “cooking” the mineral graphite with chemicals — such as sulfuric acid, sodium nitrate, potassium permanganate or hydrazine — for a long time at precisely prescribed temperatures. Additional methods involve heating hydrocarbons to 1,000 degrees Celsius in the presence of catalysts.
Such methods are energy intensive — and even dangerous — and have low yield, while Sorensen and his team’s method makes larger quantities with minimal energy and no dangerous chemicals.
“The real charm of our experiment is that we can produce graphene in the quantity of grams rather than milligrams,” Nepal said.
Now the research team — including Justin Wright, doctoral student in physics, Camp Hill, Pennsylvania — is working to improve the quality of the graphene and scale the laboratory process to an industrial level. They are upgrading some of the equipment to make it easier to get graphene from the chamber seconds — rather than minutes — after the detonation. Accessing the graphene more quickly could improve the quality of the material, Sorensen said.
The patent was issued to the Kansas State University Research Foundation, a nonprofit corporation responsible for managing technology transfer activities at the university.
I wish they’d filmed one of their graphene explosions even if it meant that all we’d get is the sight of a canister and the sound of a boom. Still, they did show a brief spark from the spark plug.
I don’t think there are many women who can carry off this garment. Of course that’s not the point as the dress is designed to show off its technical capabilities. A Jan. 31, 2017 news item on Nanowerk announces the little black graphene dress (lbgd?),
Science and fashion have been brought together to create the world’s most technically advanced dress, the intu Little Black Graphene Dress.
The new prototype garment showcases the future uses of the revolutionary, Nobel Prize winning material graphene and incorporating it into fashion for the first time, in the ultimate wearable tech statement garment.
The dress is complete with a graphene sensor which captures the rate in which the wearer is breathing via a contracting graphene band around the models waist, the micro LED which is featured across the bust on translucent conductive graphene responds to the sensor making the LED flash and changing colour depending on breathing rate. It marks a major step in the future uses of graphene in fashion where it is hoped the highly conductive transparent material could be used to create designs which act as screens showcasing digital imagery which could be programmed to change and updated by the wearer meaning one garment could be in any colour hue or design.
The 3D printed graphene filament shows the intricate structural detail of graphene in raised diamond shaped patterns and showcases graphene’s unrivalled conductivity with flashing LED lights.
The high tech LBD can be controlled by The Q app created by Cute Circuit to change the way the garment illuminates.
The dress was created by the Manchester shopping centre to celebrate Manchester’s crown as the European City of Science. The dress will then be on display at intu Trafford Centre, it will then be available for museums and galleries to loan for fashion displays.
Richard Paxton, general manager at intu Trafford Centre said: “We have a real passion for fashion and fashion firsts, this dress is a celebration of Manchester, its amazing love for innovation and textiles, showcasing this new wonder material in a truly unique and exciting way. It really is the world’s most high-tech dress featuring the most advanced super-material and something intu is very proud to have created in collaboration with Cute Circuit and the National Graphene Institute. Hopefully this project inspires more people to experiment with graphene and its wide range of uses.”
Francesca Rosella, Chief Creative Director for Cute Circuit said: “This was such an exciting project for us to get involved in, graphene has never been used in the fashion industry and being the first to use it was a real honour allowing us to have a lot of fun creating the stunning intu Little Black Graphene Dress, and showcasing graphene’s amazing properties.”
Dr Paul Wiper, Research Associate, National Graphene Institute said: “This is a fantastic project, graphene is still very much at its infancy for real-world applications and showcasing its amazing properties through the forum of fashion is very exciting. The dress is truly a one of a kind and shows what creativity, imagination and a desire to innovate can create using graphene and related two-dimensional materials.”
The dress is modelled by Britain’s Next Top Model finalist Bethan Sowerby who is from Manchester and used to work at intu Trafford Centre’s Top Shop.
I’m guessing that graphene will feature in these proposed cortical implants since the project leader is a member of the Graphene Flagship’s Biomedical Technologies Work Package. (For those who don’t know, the Graphene Flagship is one of two major funding initiatives each receiving funding of 1B Euros over 10 years from the European Commission as part of their FET [Future and Emerging Technologies)] Initiative.) A Jan. 12, 2017 news item on Nanowerk announces the new project (Note: A link has been removed),
BrainCom is a FET Proactive project, funded by the European Commission with 8.35M€ [8.3 million Euros] for the next 5 years, holding its Kick-off meeting on January 12-13 at ICN2 (Catalan Institute of Nanoscience and Nanotechnology) and the UAB [ Universitat Autònoma de Barcelona]. This project, coordinated by ICREA [Catalan Institution for Research and Advanced Studies] Research Prof. Jose A. Garrido from ICN2, will permit significant advances in understanding of cortical speech networks and the development of speech rehabilitation solutions using innovative brain-computer interfaces.
More than 5 million people worldwide suffer annually from aphasia, an extremely invalidating condition in which patients lose the ability to comprehend and formulate language after brain damage or in the course of neurodegenerative disorders. Brain-computer interfaces (BCIs), enabled by forefront technologies and materials, are a promising approach to treat patients with aphasia. The principle of BCIs is to collect neural activity at its source and decode it by means of electrodes implanted directly in the brain. However, neurorehabilitation of higher cognitive functions such as language raises serious issues. The current challenge is to design neural implants that cover sufficiently large areas of the brain to allow for reliable decoding of detailed neuronal activity distributed in various brain regions that are key for language processing.
BrainCom is a FET Proactive project funded by the European Commission with 8.35M€ for the next 5 years. This interdisciplinary initiative involves 10 partners including technologists, engineers, biologists, clinicians, and ethics experts. They aim to develop a new generation of neuroprosthetic cortical devices enabling large-scale recordings and stimulation of cortical activity to study high level cognitive functions. Ultimately, the BraimCom project will seed a novel line of knowledge and technologies aimed at developing the future generation of speech neural prostheses. It will cover different levels of the value chain: from technology and engineering to basic and language neuroscience, and from preclinical research in animals to clinical studies in humans.
This recently funded project is coordinated by ICREA Prof. Jose A. Garrido, Group Leader of the Advanced Electronic Materials and DevicesGroup at the Institut Català de Nanociència i Nanotecnologia (Catalan Institute of Nanoscience and Nanotechnology – ICN2) and deputy leader of the Biomedical Technologies Work Package presented last year in Barcelona by the Graphene Flagship. The BrainCom Kick-Off meeting is held on January 12-13 at ICN2 and the Universitat Autònoma de Barcelona (UAB).
Recent developments show that it is possible to record cortical signals from a small region of the motor cortex and decode them to allow tetraplegic [also known as, quadriplegic] people to activate a robotic arm to perform everyday life actions. Brain-computer interfaces have also been successfully used to help tetraplegic patients unable to speak to communicate their thoughts by selecting letters on a computer screen using non-invasive electroencephalographic (EEG) recordings. The performance of such technologies can be dramatically increased using more detailed cortical neural information.
BrainCom project proposes a radically new electrocorticography technology taking advantage of unique mechanical and electrical properties of novel nanomaterials such as graphene, 2D materials and organic semiconductors. The consortium members will fabricate ultra-flexible cortical and intracortical implants, which will be placed right on the surface of the brain, enabling high density recording and stimulation sites over a large area. This approach will allow the parallel stimulation and decoding of cortical activity with unprecedented spatial and temporal resolution.
These technologies will help to advance the basic understanding of cortical speech networks and to develop rehabilitation solutions to restore speech using innovative brain-computer paradigms. The technology innovations developed in the project will also find applications in the study of other high cognitive functions of the brain such as learning and memory, as well as other clinical applications such as epilepsy monitoring.
The BrainCom project Consortium members are:
Catalan Institute of Nanoscience and Nanotechnology (ICN2) – Spain (Coordinator)
Institute of Microelectronics of Barcelona (CNM-IMB-CSIC) – Spain
University Grenoble Alpes – France
ARMINES/ Ecole des Mines de St. Etienne – France
Centre Hospitalier Universitaire de Grenoble – France
Multichannel Systems – Germany
University of Geneva – Switzerland
University of Oxford – United Kingdom
Ludwig-Maximilians-Universität München – Germany
Wavestone – Luxembourg
There doesn’t seem to be a website for the project but there is a BrainCom webpage on the European Commission’s CORDIS (Community Research and Development Information Service) website.
A Jan. 6, 2017 news item on Nanowerk describes how geometry may have as much or more to do with the strength of 3D graphene structures than the graphene used to create them,
A team of researchers at MIT [Massachusetts Institute of Technology] has designed one of the strongest lightweight materials known, by compressing and fusing flakes of graphene, a two-dimensional form of carbon. The new material, a sponge-like configuration with a density of just 5 percent, can have a strength 10 times that of steel.
In its two-dimensional form, graphene is thought to be the strongest of all known materials. But researchers until now have had a hard time translating that two-dimensional strength into useful three-dimensional materials.
The new findings show that the crucial aspect of the new 3-D forms has more to do with their unusual geometrical configuration than with the material itself, which suggests that similar strong, lightweight materials could be made from a variety of materials by creating similar geometric features.
The findings are being reported today [Jan. 6, 2017\ in the journal Science Advances, in a paper by Markus Buehler, the head of MIT’s Department of Civil and Environmental Engineering (CEE) and the McAfee Professor of Engineering; Zhao Qin, a CEE research scientist; Gang Seob Jung, a graduate student; and Min Jeong Kang MEng ’16, a recent graduate.
Other groups had suggested the possibility of such lightweight structures, but lab experiments so far had failed to match predictions, with some results exhibiting several orders of magnitude less strength than expected. The MIT team decided to solve the mystery by analyzing the material’s behavior down to the level of individual atoms within the structure. They were able to produce a mathematical framework that very closely matches experimental observations.
Two-dimensional materials — basically flat sheets that are just one atom in thickness but can be indefinitely large in the other dimensions — have exceptional strength as well as unique electrical properties. But because of their extraordinary thinness, “they are not very useful for making 3-D materials that could be used in vehicles, buildings, or devices,” Buehler says. “What we’ve done is to realize the wish of translating these 2-D materials into three-dimensional structures.”
The team was able to compress small flakes of graphene using a combination of heat and pressure. This process produced a strong, stable structure whose form resembles that of some corals and microscopic creatures called diatoms. These shapes, which have an enormous surface area in proportion to their volume, proved to be remarkably strong. “Once we created these 3-D structures, we wanted to see what’s the limit — what’s the strongest possible material we can produce,” says Qin. To do that, they created a variety of 3-D models and then subjected them to various tests. In computational simulations, which mimic the loading conditions in the tensile and compression tests performed in a tensile loading machine, “one of our samples has 5 percent the density of steel, but 10 times the strength,” Qin says.
Buehler says that what happens to their 3-D graphene material, which is composed of curved surfaces under deformation, resembles what would happen with sheets of paper. Paper has little strength along its length and width, and can be easily crumpled up. But when made into certain shapes, for example rolled into a tube, suddenly the strength along the length of the tube is much greater and can support substantial weight. Similarly, the geometric arrangement of the graphene flakes after treatment naturally forms a very strong configuration.
The new configurations have been made in the lab using a high-resolution, multimaterial 3-D printer. They were mechanically tested for their tensile and compressive properties, and their mechanical response under loading was simulated using the team’s theoretical models. The results from the experiments and simulations matched accurately.
The new, more accurate results, based on atomistic computational modeling by the MIT team, ruled out a possibility proposed previously by other teams: that it might be possible to make 3-D graphene structures so lightweight that they would actually be lighter than air, and could be used as a durable replacement for helium in balloons. The current work shows, however, that at such low densities, the material would not have sufficient strength and would collapse from the surrounding air pressure.
But many other possible applications of the material could eventually be feasible, the researchers say, for uses that require a combination of extreme strength and light weight. “You could either use the real graphene material or use the geometry we discovered with other materials, like polymers or metals,” Buehler says, to gain similar advantages of strength combined with advantages in cost, processing methods, or other material properties (such as transparency or electrical conductivity).
“You can replace the material itself with anything,” Buehler says. “The geometry is the dominant factor. It’s something that has the potential to transfer to many things.”
The unusual geometric shapes that graphene naturally forms under heat and pressure look something like a Nerf ball — round, but full of holes. These shapes, known as gyroids, are so complex that “actually making them using conventional manufacturing methods is probably impossible,” Buehler says. The team used 3-D-printed models of the structure, enlarged to thousands of times their natural size, for testing purposes.
For actual synthesis, the researchers say, one possibility is to use the polymer or metal particles as templates, coat them with graphene by chemical vapor deposit before heat and pressure treatments, and then chemically or physically remove the polymer or metal phases to leave 3-D graphene in the gyroid form. For this, the computational model given in the current study provides a guideline to evaluate the mechanical quality of the synthesis output.
The same geometry could even be applied to large-scale structural materials, they suggest. For example, concrete for a structure such a bridge might be made with this porous geometry, providing comparable strength with a fraction of the weight. This approach would have the additional benefit of providing good insulation because of the large amount of enclosed airspace within it.
Because the shape is riddled with very tiny pore spaces, the material might also find application in some filtration systems, for either water or chemical processing. The mathematical descriptions derived by this group could facilitate the development of a variety of applications, the researchers say.
“This is an inspiring study on the mechanics of 3-D graphene assembly,” says Huajian Gao, a professor of engineering at Brown University, who was not involved in this work. “The combination of computational modeling with 3-D-printing-based experiments used in this paper is a powerful new approach in engineering research. It is impressive to see the scaling laws initially derived from nanoscale simulations resurface in macroscale experiments under the help of 3-D printing,” he says.
This work, Gao says, “shows a promising direction of bringing the strength of 2-D materials and the power of material architecture design together.”
Heat is always a problem with electronics—even nanoelectronics. Scientists at Rice University (US) believe they may have a solution for nanoelectronics heat problems, according to a Jan. 4, 2017 news item on ScienceDaily,
A few nanoscale adjustments may be all that is required to make graphene-nanotube junctions excel at transferring heat, according to Rice University scientists.
The Rice lab of theoretical physicist Boris Yakobson found that putting a cone-like “chimney” between the graphene and [carbon] nanotube all but eliminates a barrier that blocks heat from escaping.
Caption: Simulations by Rice University scientists show that placing cones between graphene and carbon nanotubes could enhance heat dissipation from nano-electronics. The nano-chimneys become better at conducting heat-carrying phonons by spreading out the number of heptagons required by the graphene-to-nanotube transition. Credit: Alex Kutana/Rice University
Heat is transferred through phonons, quasiparticle waves that also transmit sound. The Rice theory offers a strategy to channel damaging heat away from next-generation nano-electronics.
Both graphene and carbon nanotubes consist of six-atom rings, which create a chicken-wire appearance, and both excel at the rapid transfer of electricity and phonons.
But when a nanotube grows from graphene, atoms facilitate the turn by forming heptagonal (seven-member) rings instead. Scientists have determined that forests of nanotubes grown from graphene are excellent for storing hydrogen for energy applications, but in electronics, the heptagons scatter phonons and hinder the escape of heat through the pillars.
The Rice researchers discovered through computer simulations that removing atoms here and there from the two-dimensional graphene base would force a cone to form between the graphene and the nanotube. The geometric properties (aka topology) of the graphene-to-cone and cone-to-nanotube transitions require the same total number of heptagons, but they are more sparsely spaced and leave a clear path of hexagons available for heat to race up the chimney.
“Our interest in advancing new applications for low-dimensional carbon — fullerenes, nanotubes and graphene — is broad,” Yakobson said. “One way is to use them as building blocks to fill three-dimensional spaces with different designs, creating anisotropic, nonuniform scaffolds with properties that none of the current bulk materials have. In this case, we studied a combination of nanotubes and graphene, connected by cones, motivated by seeing such shapes obtained in our colleagues’ experimental labs.”
The researchers tested phonon conduction through simulations of free-standing nanotubes, pillared graphene and nano-chimneys with a cone radius of either 20 or 40 angstroms. The pillared graphene was 20 percent less conductive than plain nanotubes. The 20-angstrom nano-chimneys were just as conductive as plain nanotubes, while 40-angstrom cones were 20 percent better than the nanotubes.
“The tunability of such structures is virtually limitless, stemming from the vast combinatorial possibilities of arranging the elementary modules,” said Alex Kutana, a Rice research scientist and co-author of the study. “The actual challenge is to find the most useful structures given a vast number of possibilities and then make them in the lab reliably.
“In the present case, the fine-tuning parameters could be cone shapes and radii, nanotube spacing, lengths and diameters. Interestingly, the nano-chimneys also act like thermal diodes, with heat flowing faster in one direction than the other,” he said.