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

New battery electrolyte may boost the performance of electric vehicles

Posted By Graphene Council, Wednesday, June 24, 2020
A new lithium-based electrolyte invented by Stanford University scientists could pave the way for the next generation of battery-powered electric vehicles.

In a study published June 22 in Nature Energy, Stanford researchers demonstrate how their novel electrolyte design boosts the performance of lithium metal batteries, a promising technology for powering electric vehicles, laptops and other devices.

"Most electric cars run on lithium-ion batteries, which are rapidly approaching their theoretical limit on energy density," said study co-author Yi Cui, professor of materials science and engineering and of photon science at the SLAC National Accelerator Laboratory. "Our study focused on lithium metal batteries, which are lighter than lithium-ion batteries and can potentially deliver more energy per unit weight and volume."

Lithium-ion batteries, used in everything from smartphones to electric cars, have two electrodes -- a positively charged cathode containing lithium and a negatively charged anode usually made of graphite. An electrolyte solution allows lithium ions to shuttle back and forth between the anode and the cathode when the battery is used and when it recharges.

A lithium metal battery can hold about twice as much electricity per kilogram as today's conventional lithium-ion battery. Lithium metal batteries do this by replacing the graphite anode with lithium metal, which can store significantly more energy.

"Lithium metal batteries are very promising for electric vehicles, where weight and volume are a big concern," said study co-author Zhenan Bao, the K.K. Lee Professor in the School of Engineering. "But during operation, the lithium metal anode reacts with the liquid electrolyte. This causes the growth of lithium microstructures called dendrites on the surface of the anode, which can cause the battery to catch fire and fail."

Researchers have spent decades trying to address the dendrite problem.

"The electrolyte has been the Achilles' heel of lithium metal batteries," said co-lead author Zhiao Yu, a graduate student in chemistry. "In our study, we use organic chemistry to rationally design and create new, stable electrolytes for these batteries."

For the study, Yu and his colleagues explored whether they could address the stability issues with a common, commercially available liquid electrolyte.

"We hypothesized that adding fluorine atoms onto the electrolyte molecule would make the liquid more stable," Yu said. "Fluorine is a widely used element in electrolytes for lithium batteries. We used its ability to attract electrons to create a new molecule that allows the lithium metal anode to function well in the electrolyte."

The result was a novel synthetic compound, abbreviated FDMB, that can be readily produced in bulk.

"Electrolyte designs are getting very exotic," Bao said. "Some have shown good promise but are very expensive to produce. The FDMB molecule that Zhiao came up with is easy to make in large quantity and quite cheap."

The Stanford team tested the new electrolyte in a lithium metal battery.

The results were dramatic. The experimental battery retained 90 percent of its initial charge after 420 cycles of charging and discharging. In laboratories, typical lithium metal batteries stop working after about 30 cycles.

The researchers also measured how efficiently lithium ions are transferred between the anode and the cathode during charging and discharging, a property known as "coulombic efficiency."

"If you charge 1,000 lithium ions, how many do you get back after you discharge?" Cui said. "Ideally you want 1,000 out of 1,000 for a coulombic efficiency of 100 percent. To be commercially viable, a battery cell needs a coulombic efficiency of at least 99.9 percent. In our study we got 99.52 percent in the half cells and 99.98 percent in the full cells; an incredible performance."

For potential use in consumer electronics, the Stanford team also tested the FDMB electrolyte in anode-free lithium metal pouch cells -- commercially available batteries with cathodes that supply lithium to the anode.

"The idea is to only use lithium on the cathode side to reduce weight," said co-lead author Hansen Wang, a graduate student in materials science and engineering. "The anode-free battery ran 100 cycles before its capacity dropped to 80 percent -- not as good as an equivalent lithium-ion battery, which can go for 500 to 1,000 cycles, but still one of the best performing anode-free cells."

"These results show promise for a wide range of devices," Bao added. "Lightweight, anode-free batteries will be an attractive feature for drones and many other consumer electronics."

The U.S. Department of Energy (DOE) is funding a large research consortium called Battery500 to make lithium metal batteries viable, which would allow car manufacturers to build lighter electric vehicles that can drive much longer distances between charges. This study was supported in part by a grant from the consortium, which includes Stanford and SLAC.

By improving anodes, electrolytes and other components, Battery500 aims to nearly triple the amount of electricity that a lithium metal battery can deliver, from about 180 watt-hours per kilogram when the program started in 2016 to 500 watt-hours per kilogram. A higher energy-to-weight ratio, or "specific energy," is key to solving the range anxiety that potential electric car buyers often have.

"The anode-free battery in our lab achieved about 325 watt-hours per kilogram specific energy, a respectable number," Cui said. "Our next step could be to work collaboratively with other researchers in Battery500 to build cells that approach the consortium's goal of 500 watt-hours per kilogram."

In addition to longer cycle life and better stability, the FDMB electrolyte is also far less flammable than conventional electrolytes.

"Our study basically provides a design principle that people can apply to come up with better electrolytes," Bao added. "We just showed one example, but there are many other possibilities."

Tags:  Battery  electric vehicle  Graphene  Li-ion Batteries  SLAC National Accelerator Laboratory  Yi Cui  Zhenan Bao 

Share |
PermalinkComments (0)
 

'Unboil an egg' machine creates improved bacteria detector

Posted By Graphene Council, Wednesday, June 24, 2020
The versatility of the Vortex Fluidic Device (VFD), a device that famously unboiled an egg, continues to impress, with the innovative green chemistry device created at Flinders University having more than 100 applications – including the creation of a new non-toxic fluorescent dye that detects bacteria harmful to humans.

Traditional fluorescent dyes to examine bacteria viability are toxic and suffer poor photostability – but using the VFD has enabled the preparation of a new generation of aggregation-induced emission dye (AIE) luminogens using graphene oxide (GO), thanks to collaborative research between Flinders University’s Institute for NanoScale Science and Technology and the Centre for Health Technologies, University of Technology Sydney.

Using the VFD to produce GO/AIE probes with the property of high fluorescence is without precedent – with the new GO/AIE nanoprobe having 1400% brighter high fluorescent performance than AIE luminogen alone (Materials Chemistry Frontiers, "Vortex fluidic enabling and significantly boosting light intensity of graphene oxide with aggregation induced emission luminogen").

“It’s crucial to develop highly sensitive ways of detecting bacteria that pose a potential threat to humans at the early stage, so health sectors and governments can be informed promptly, to act quickly and efficiently,” says Flinders University researcher Professor Youhong Tang.

“Our GO/AIE nanoprobe will significantly enhance long-term tracking of bacteria to effectively control hospital infections, as well as developing new and more efficient antibacterial compounds.”

The VFD is a new type of chemical processing tool, capable of instigating chemical reactivity, enabling the controlled processing of materials such as mesoporous silica, and effective in protein folding under continuous flow, which is important in the pharmaceutical industry. It continues to impress researchers for its adaptability in green chemistry innovations.

“Developing such a deep understanding of bacterial viability is important to revise infection control policies and invent effective antibacterial compounds,” says lead author of the research, Dr Javad Tavakoli, a previous researcher from Professor Youhong Tang’s group, and now working at the University of Technology Sydney.

“The beauty of this research was developing a highly bright fluorescence dye based on graphene oxide, which has been well recognised as an effective fluorescence quenching material.”

The type of AIE luminogen was first developed in 2015 to enable long-term monitoring of bacterial viability, however, increasing its brightness to increase sensitivity and efficiency remained a difficult challenge. Previous attempts to produce AIE luminogen with high brightness proved very time-consuming, requires complex chemistry, and involves catalysts rendering their mass production expensive.

By comparison, the Vortex Fluidic Device allows swift and efficient processing beyond batch production and the potential for cost-effective commercialisation.

Increasing the fluorescent property of GO/AIE depends on the concentration of graphene oxide, the rotation speed of the VFD tube, and the water fraction in the compound – so preparing GO/AIE under the shear stress induced by the VFD’s high-speed rotating tube resulted in much brighter probes with significantly enhanced fluorescent intensities.

Tags:  Flinders University  Graphene  graphene oxide  Healthcare  Youhong Tang 

Share |
PermalinkComments (0)
 

BAC's ALL-NEW MONO R: HIGHER-PERFORMANCE, LIGHTER, MORE ADVANCED GEN2 MONO DUE FOR DELIVERY IN Q3 2020

Posted By Graphene Council, Tuesday, June 23, 2020
Updated: Friday, June 26, 2020

In July 2019, we announced that Briggs Automotive Company (BAC) officially launched the all-new Mono R – a higher-performance, lighter and more advanced new generation of the iconic Mono.

In a recent discussion with Neill Briggs, Co-Founder and Director of Product Development, he confirmed to The Graphene Council that the first customer cars are currently being produced and are due for delivery in Q3’ 2020.

We are sharing the prior announcement to reflect on the major advances and roles that graphene is playing in this very exciting product. 

***

Mono R serves as The New Reference – the very pinnacle of design, innovation and engineering. It sports a stunning new generation of Mono DNA, features revolutionary new materials and technology and offers world-beating performance on the road and track.

R is 35bhp more powerful and 25kg lighter than the standard Mono, at 340bhp and 555kg – equating to a truly remarkable power-to-weight ratio of 612bhp-per-tonne.

Mono R is one of the most exclusive supercars ever made, with a total of just 30 models being produced and sold to existing Mono customers around the globe. Ahead of its launch at the Goodwood Festival of Speed 2019, the full production run of Mono R has sold out worldwide.

Design

Although still undeniably Mono, the R sports a stunning new generation of the single-seater’s design DNA. A brand new approach to body engineering has seen all surfaces designed from scratch and 44 bespoke carbon parts restyled to give the car a more aggressive, organic and futuristic stance.

The striking new look of Mono R is defined by the imposing shark nose front, which epitomises true efficiency of form courtesy of a sleek and homogeneous redesign. Main beam LED headlights centrally mounted on the nose are a distinguishing feature that reduce the frontal area and contribute to a more minimalist appearance.

The new nose coupled with the Formula-inspired ram-air inlet system issue a hint at the R’s phenomenal performance potential, while the upper body design is more slender and organic to enhance aerodynamics. Lower down on the R, all technical surfaces are thinner and more blade-like to effectively sculpt and divert airflow.

Mono R’s sleeker and tighter appearance has been achieved by reductions in visible mass across the full body; plus there’s been a 20mm reduction in overall height and a 25mm increase in length over the standard Mono.

The R has been the subject of numerous aerodynamic enhancements, with more efficient front arches and wider sidepods as well as a larger and more aerodynamically efficient rear spoiler extending over the rear arches.

New LED lights, twin-strut wing mirrors, rear crash box and a narrower tail incorporating new LED combination fog and reverse lights complete the exquisite look.

Inside, the Mono R remains a perfect canvas for customer personalisation, plus there’s a new-look, race-inspired, even lighter steering wheel and optional carbon interior side panels.

Power

Having set The New Reference for design, BAC’s talented engineers have ensured Mono R breaks new ground with its engine, too. Co-developed with long-standing engine partner Mountune, the Mono’s 2.5-litre, four-cylinder unit has increased in power by 35bhp to deliver an astonishing 340bhp.

BAC and Mountune left no stone unturned when it came to meeting power targets: increasing the cylinder bore size and reducing new billet crankshaft stroke to optimise power and torque delivery and increase rpm from 7,800rpm to 8,800rpm.

The striking new Formula-inspired ram-air inlet system provides pressurised air into an all-new throttle body and cylinder head system to further increase power, plus a higher-spec, drive-by-wire motor allows for a quicker throttle response.

As a result, the bespoke Mountune engine now offers 136bhp per litre – a new naturally aspirated global record for a road-legal model.

Innovation

Mono R is the first production car in the world fully incorporating the use of graphene-enhanced carbon fibre in every body panel. Using the revolutionary material enhances the structural properties of the fibre to make panels stronger and lighter with improved mechanical and thermal performance. 

The brand’s latest world first comes as a result of a successful APC-funded Research & Development project into the production-readiness of graphene. Working alongside Haydale and Pentaxia through the Niche Vehicle Network (NVN), BAC is now launching the advantages into series production.

BAC has also teamed up with global science corporation DSM to use additive manufacturing for the first time on Mono R. By 3D printing parts using high-performance polymers, BAC has been able to reduce the design-to-manufacture timeframes of complex geometrical components as well as save further weight.

Elsewhere, magnesium chassis and transmission components combine to reduce mass and improve weight distribution, while new carbon-ceramic brakes – which save 2.55kg of unsprung mass per corner – are fitted as standard.

Add all of this to a new titanium exhaust system, lighter AP Racing brake calipers and an all-new carbon floor, and Mono R weighs in at a significant 25kg less than the standard Mono, at just 555kg.

Ultimate Driving Experience

Mono R achieves the ultimate driving experience not only with its remarkable power and innovation, but also through various subtle vehicle dynamic enhancements.

Suspension geometry has been optimised to reduce pitch under braking, with increased anti-dive at the front and anti-squat at the rear maximising traction, while two-way adjustable dampers from renowned Swedish experts Öhlins feature for the first time.

The fuel tank has increased in volume and been lowered and the battery has been repositioned to the centre of the car underneath the driver for optimum balance – thus lowering the centre of gravity and improving weight distribution to near-perfect proportions.

The vehicle dynamic improvements combine to reduce braking distances and weight transfer, helping to deliver sharper turn-in, provide better rotation at the apex and better traction out of corners – aided by specially homologated Pirelli Trofeo R tyres being fitted as standard on all Mono R models.

This together with lighter weight, more power and more efficient aerodynamics means BAC has found the perfect recipe for ultimate success: faster lap times on the track and a world-beating, head-turning driving experience on the road – The New Reference for what a driving machine can offer.

Ian Briggs, Design Director at BAC, said: “Today marks a monumental step in the history of Briggs Automotive Company. Not only have we become a multi-product brand for the first time, but we’ve done so with a truly remarkable feat of engineering, design and innovation in the Mono R. It’s the first time since we first laid plans for Mono a decade ago that we’ve designed something brand new – and that’s testament to the success of the business and Mono that we’ve reached this point. Mono R has been many, many years in the making, with thousands upon thousands of hours of research and work going into it – and we believe we’ve found the perfect formula for creating the most extreme Mono in the flesh and under the skin.”

Neill Briggs, BAC’s Director of Product Development, added: “Welcome to Mono R – The New Reference. This car is the ultimate benchmark-setter in terms of design, engineering and performance; that much is evident from the fact we sold out our full run of 30 models almost immediately to our very lucky current customers, who have a real treat in store when they get behind the wheel. It’s a result of exceptional teamwork by all of our employees, suppliers and partners and something for everyone associated with BAC to be extremely proud of. Mono R sets The New Reference as the pinnacle of what’s possible from a supercar, but also for what’s following from BAC in years to come – these are very exciting times indeed.”

Tags:  Briggs Automotive Company  Graphene  Ian Briggs  Neill Briggs 

Share |
PermalinkComments (0)
 

Researchers pioneer new production method for heterostructure devices

Posted By Graphene Council, Tuesday, June 23, 2020
Researchers at the University of Exeter have developed a pioneering production method for heterostructure devices, based on 2D materials such as graphene.

The new study, published in Nature Communications, focuses on a production method, based around mechanical abrasion, where multilayer structures are formed through directly abrading different Van der Waals material powders directly on top of one another.

The new technique saw sharp heterointerfaces emerge for certain heterostructure combinations. The results pave the way for a wide range of heterointerface based devices to be opened up.

To demonstrate the applicability of this method, researchers demonstrated a multitude of different functional devices such as resistors, capacitors, transistors, diodes and photovoltaics.

The work also demonstrated the use of these films for energy applications such as in triboelectric nanogenerator devices and as a catalyst in the hydrogen evolution reaction.

Darren Nutting, from the University of Exeter and co-author of the study said: “The production method is really simple, you can go from bare substrate to functional heterostructure device within about 10 minutes.

“This is all without the need for complex growth conditions, 20 hours of ultra-sonication or messy liquid phase production.

“The method is applicable to any 2D material crystal, and can easily be automated to produce heterostructures of arbitrary size and complexity. This allows for the production of a plethora of device possibilities with superior performance to those created using more complex methods.”

Dr Freddie Withers, also from the University of Exeter and lead author added: “The most interesting and surprising aspect of this work is that sharply defined heterointerfaces can be realised through direct abrasion, which we initially expected would lead to an intermixing of materials when directly abrading layer by layer. This observation allows for a large number of different devices to be realised through an extremely simple and low-cost fabrication process.

“We also found that the performance of our materials significantly outperform the performance of competitive scalable 2D materials production technologies. We think this is due to larger crystallite sizes and cleaner crystallite interfaces within our films. Considering the rudimentary development of the abrasive process thus far, it will be interesting to see how far we can push the performance levels.”

Tags:  2D materials  Darren Nutting  Graphene  transistor  University of Exeter 

Share |
PermalinkComments (0)
 

Applied Graphene Materials presents to automotive and aerospace engineers

Posted By Graphene Council, Tuesday, June 23, 2020
SAE International, the global community of 200,000 automotive and aerospace engineers, hosted a virtual conference, WCX Digital Summit, on 16-18 June 2020.

As a guest speaker with The Graphene Council, Adrian Potts CEO, of Applied Graphene Materials gave a presentation titled ‘Graphene for Automotive Applications - Lighter, Stronger, Better

Dr. Potts talks about how to turn the remarkable performance of graphene into reality. Having the application technology to formulate a graphene-based dispersion correctly can make great use of the material’s advantages. The combination of a deep engagement with the end customer, understanding of their objectives, and AGM’s customized graphene dispersion solutions is delivering unique materials performance gains in a number of relevant areas to the automotive industry.

AGM are also leading the way in regulatory matters for use in nano-materials and have an impressive collection of data to support the end user, with practical ‘how-to’ knowledge that enables easy use of graphene.

This session highlighted the different ways graphene can be used to enhance performance in automotive applications.

•   Lighter & Tougher     Graphene in Composites
•   Lighter & Better        Graphene in Thermal applications
•   Better & Longer Life Graphene in Coatings

Tags:  Adrian Potts  Applied Graphene Materials  Graphene  SAE International 

Share |
PermalinkComments (0)
 

Vapor fix lifts up perovskite crystal performance

Posted By Graphene Council, Saturday, June 20, 2020
A simple and noninvasive treatment could become a prime post-crystallization process to optimize the optoelectronic properties of hybrid perovskite solar cell materials.

In this treatment devised by KAUST, bromine vapors penetrate the surface of as-synthesized perovskite crystals to reach their deep-lying layers, removing surface and bulk defects generated during crystal growth.

Lead-containing hybrid perovskites, such as methylammonium lead tribromide (MAPbBr3), present unique charge transport properties and easy processability in solution. These make them attractive as potential low-cost alternatives to traditional silicon-based light-harvesting solar cell materials. However, approaches that use solution processing to crystalize them tend to leave contaminants, such as oxygen and amorphous carbon. These approaches also produce halide vacancies that create lead cations, which can trap electrons to form metallic lead and restrict charge transport.

Various chemical treatments can reduce these defects, but most tinker with the composition of the precursor solution to optimize thin film and crystal formation. However, the researchers from the KAUST Solar Center sought something simpler.

"We were interested in developing a facile recipe that could be applied once crystal formation was complete," says Ahmad Kirmani, now a postdoc at the National Renewable Energy Laboratory, U.S., who conducted the study under the supervision of Aram Amassian and Omar Mohammed.

Co-author Ahmed Mansour, now a postdoc at Helmholtz-Zentrum Berlin, Germany, describes how the researchers chose a bromine vapor treatment because they had previously observed the improved conductivity of graphene when exposed to bromine. "Bromine is a volatile liquid at room temperature and readily evaporates without the need for any external source of energy," Mansour says.

The researchers suspended MAPbBr3 crystals in a bromine-vapor-saturated environment and monitored the effects of bromine exposure on material properties.

They were pleasantly surprised to find that bromine vapors suppressed metallic lead on the surface as well as in the bulk of the crystals, Mohammed says. "This meant that we could access the bulk properties of these crystals, such as their electrical conductivity," he adds. Prolonged bromine exposure produced a dramatic 10,000-fold enhancement in bulk electrical conductivity and a 50-fold increase in carrier mobility. Further assessment revealed that perovskite crystallization leaves behind voids and imperfections, which allows bromine to diffuse and permeate through the crystals.

Each of the former team members is currently exploring more applications for their treatment, such as for improving the power conversion efficiency of solar cells containing perovskite thin films as absorbers or for single-crystal devices--such as transistors, photodetectors and radiation detectors--that require excellent carrier mobility and intrinsic optoelectronic properties.

Tags:  Ahmad Kirmani  Graphene  KAUST  Omar Mohammed  optoelectronics 

Share |
PermalinkComments (0)
 

Manchester launches spin-out to bring innovative water-filtration technology to market

Posted By Graphene Council, Saturday, June 20, 2020
Scientists and innovation experts from The University of Manchester have worked together to successfully develop a new, market-ready technology using 2D materials that could be a game-changer for the water filtration sector.
ollowing an 18-month technical development and business planning programme - funded by the University - the team of innovators has launched a spin-out company called Molymem Limited to help take the new membrane product into the marketplace. The technology has applications in the pharmaceutical, wastewater management and food and beverage sectors.

The breakthrough development of a high-performing membrane coating is based around a new class of 2D materials, pioneered by Manchester researchers Professor Rob Dryfe and Dr Mark Bissett (pictured right), working with Clive Rowland, team leader for the Molymem project and the University’s Associate Vice-President for Intellectual Property.

Clive explained that membranes are used globally for separation applications in a wide range of valuable markets. “But all of these applications can be expensive,” he added. “They consume high energy and are prone to fouling - and, as a result, require frequent deep cleaning with corrosive chemicals. This causes lost production time and, due to the harsh nature of chemicals being used, it also leads to a deterioration in membrane quality over time.”

Using chemically modified molybdenum disulphide (MoS2), which is widely available at low cost and easily processed, Molymem has developed an energy-efficient and highly versatile membrane coating.

Fast-track innovation
Much of the lab-to-market work was carried out at the Graphene Engineering Innovation Centre (GEIC), which is dedicated to the fast-tracking of pilot innovation around graphene and other 2D materials. Graphene is the world’s first man-made 2D material and offers a range of disruptive capabilities.

Molymem is now ideally placed to raise investment capital to embark on its commercial journey – and interest has already been shown by industrial partners.

James Baker, CEO Graphene@Manchester, said: “The Molymem project demonstrates how the Graphene Engineering Innovation Centre can help to accelerate a breakthrough development in materials science into a brand-new, market-ready product.

“Molymem will now be mentored within the Graphene@Manchester innovation ecosystem as part our portfolio of graphene-based spin-outs. This includes bespoke support such as fundraising for future business development and rapid market development.”

Clive Rowland added: “Over the summer, I will hand-over the team leadership to Ray Gibbs, who is managing the University's graphene and 2D materials spin-out portfolio. Ray will look to fundraise and help take Molymem to the next stage of its exciting innovation journey.”

Tags:  2D materials  Clive Rowland  Graphene  Graphene Engineering Innovation Centre  James Baker  Mark Bissett  Rob Dryfe  University of Manchester  water purification 

Share |
PermalinkComments (0)
 

Graphene smart textiles developed for heat adaptive clothing

Posted By Graphene Council, Thursday, June 18, 2020
New research on the two-dimensional (2D) material graphene has allowed researchers to create smart adaptive clothing which can lower the body temperature of the wearer in hot climates.

A team of scientists from The University of Manchester’s National Graphene Institute have created a prototype garment to demonstrate dynamic thermal radiation control within a piece of clothing by utilising the remarkable thermal properties and flexibility of graphene. The development also opens the door to new applications such as, interactive infrared displays and covert infrared communication on textiles.

The human body radiates energy in the form of electromagnetic waves in the infrared spectrum (known as blackbody radiation). In a hot climate it is desirable to make use the full extent of the infrared radiation to lower the body temperature which can be achieved by using infrared-transparent textiles. As for the opposite case, infrared-blocking covers are ideal to minimise the energy loss from the body. Emergency blankets are a common example used to deal with treating extreme cases of body temperature fluctuation.

The collaborative team of scientists demonstrated the dynamic transition between two opposite states by electrically tuning the infrared emissivity (the ability to radiate energy) of graphene layers integrated onto textiles.

One-atom thick graphene was first isolated and explored in 2004 at The University of Manchester. Its potential uses are vast and research has already led to leaps forward in commercial products including; batteries, mobile phones, sporting goods and automotive.

The new research published today in journal Nano Letters, demonstrates that the smart optical textile technology can change its thermal visibility. The technology uses graphene layers to control of thermal radiation from textile surfaces.

The successful demonstration of the modulation of optical properties on different forms of textile can leverage the ubiquitous use of fibrous architectures and enable new technologies operating in the infrared and other regions of the electromagnetic spectrum for applications including textile displays, communication, adaptive space suits, and fashion. Professor Coskun Kocabas

Professor Coskun Kocabas, who led the research, said: “Ability to control the thermal radiation is a key necessity for several critical applications such as temperature management of the body in excessive temperature climates. Thermal blankets are a common example used for this purpose. However, maintaining these functionalities as the surroundings heats up or cools down has been an outstanding challenge.”

Prof Kocabas added: “The successful demonstration of the modulation of optical properties on different forms of textile can leverage the ubiquitous use of fibrous architectures and enable new technologies operating in the infrared and other regions of the electromagnetic spectrum for applications including textile displays, communication, adaptive space suits, and fashion.”

This study built on the same group’s previous research using graphene to create thermal camouflage which was able to fool infrared cameras. The new research can also be integrated into existing mass-manufacture textile materials such as cotton. To demonstrate, the team developed a prototype product within a t-shirt allowing the wearer to project coded messages invisible to the naked eye but readable by infrared cameras.

“We believe that our results are timely showing the possibility of turning the exceptional optical properties of graphene into novel enabling technologies. The demonstrated capabilities cannot be achieved with conventional materials.

“The next step for this area of research is to address the need for dynamic thermal management of earth-orbiting satellites. Satellites in orbit experience excesses of temperature, when they face the sun and they freeze in the earth’s shadow. Our technology could enable dynamic thermal management of satellites by controlling the thermal radiation and regulate the satellite temperature on demand.” said Kocabas.

Professor Sir Kostya Novoselov was also involved in the research: “This is a beautiful effect, intrinsically routed in the unique band structure of graphene. It is really exciting to see that such effects give rise to these high-tech applications.” he said.

Tags:  2D material  Coskun Kocabas  Graphene  nanoparticles  textile  University of Manchester 

Share |
PermalinkComments (0)
 

Risk analyses for nanoparticles Nanosafety research without animal experiments

Posted By Graphene Council, Thursday, June 18, 2020
They are already in use in, say, cosmetics and the textile industry: Nanoparticles in sun blockers protect us from sunburn, and clothing with silver nanoparticles slows down bacterial growth. But the use of these tiny ingredients is also linked to the responsibility of being able to exclude negative effects for health and the environment. Nanoparticles belong to the still poorly characterized class of nanomaterials, which are between one and 100 nanometers in size and have a wide range of applications, for example in exhaust gas catalytic converters, wall paints, plastics and in nanomedicine. As new and unusual as nanomaterials are, it is still not clear whether or not they pose any risks to humans or the environment.

This is where risk analyses and life cycle assessments (LCA) come into play, which used to rely strongly on animal experiments when it came to determining the harmful effects of a new substance, including toxicity. Today, research is required to reduce and replace animal experiments wherever possible. Over the past 30 years, this approach has led to a substantial drop in animal testing, particularly in toxicological tests. The experience gained with conventional chemicals cannot simply be transferred to novel substances such as nanoparticles, however. Empa scientists are now developing new approaches, which should allow another substantial reduction in animal testing while at the same time enabling the safe use of nanomaterials.

"We are currently developing a new, integrative approach to analyze the risks of nanoparticles and to perform life cycle assessments," says Beatrice Salieri from Empa's Technology and Society lab in St. Gallen. One new feature, and one which differs from conventional analyses, is that, in addition to the mode of action of the substance under investigation, further data is included, such as the exposure and fate of a particle in the human body, so that a more holistic view is incorporated into the risk assessment.

These risk analyses are based on the nanoparticles' biochemical properties in order to develop suitable laboratory experiments, for example with cell cultures. To make sure the results from the test tube ("in vitro") also apply to the conditions in the human body ("in vivo"), the researchers use mathematical models ("in silico"), which, for instance, rely on the harmfulness of a reference substance. "If two substances, such as silver nanoparticles and silver ions, act in the very same way, the potential hazard of the nanoparticles can be calculated from that," says Salieri. 

But for laboratory studies on nanoparticles to be conclusive, a suitable model system must first be developed for each type of nanoparticle. "Substances that are inhaled are examined in experiments with human lung cells," explains Empa researcher Peter Wick who is heading the "Particles-Biology Interactions" lab in St. Gallen. On the other hand, intestinal or liver cells are used to simulate digestion in the body.

This not only determines the damaging dose of a nanoparticle in cell culture experiments, but also includes all biochemical properties in the risk analysis, such as shape, size, transport patterns and the binding – if any – to other molecules. For example, free silver nanoparticles in a cell culture medium are about 100 times more toxic than silver nanoparticles bound to proteins. Such comprehensive laboratory analyses are incorporated into so-called kinetic models, which, instead of a snapshot of a situation in the test tube, can depict the complete process of particle action.

Finally, with the aid of complex algorithms, the expected biological phenomena can be calculated from these data. "Instead of 'mixing in' an animal experiment every now and then, we can determine the potential risks of nanoparticles on the basis of parallelisms with well-known substances, new data from lab analyses and mathematical models," says Empa researcher Mathias Rösslein. In future, this might also enable us to realistically represent the interactions between different nanoparticles in the human body as well as the characteristics of certain patient groups, such as elderly people or patients with several diseases, the scientist adds.

As a result of these novel risk analyses for nanoparticles, the researchers also hope to accelerate the development and market approval of new nanomaterials. They are already being applied in the "Safegraph" project, one of the projects in the EU's "Graphene Flagship" initiative, in which Empa is involved as a partner. Risk analyses and LCA for the new "wonder material" graphene are still scarce. Empa researchers have recently been able to demonstrate initial safety analyses of graphene and graphene related materials in fundamental in vitro studies. In this way, projects such as Safegraph can now better identify potential health risks and environmental consequences of graphene, while at the same time reducing the number of animal experiments.

Tags:  Beatrice Salieri  Empa  Graphene  Medicine  nanomaterials  nanoparticles 

Share |
PermalinkComments (0)
 

CERN trials graphene for magnetic measurements

Posted By Graphene Council, Thursday, June 18, 2020
First isolated in 2004 by physicists at the University of Manchester using pieces of sticky tape and a graphite block, the one-atom-thick carbon allotrope graphene has been touted as a wonder material on account of its exceptional electrical, thermal and physical properties. Turning these properties into scalable commercial devices has proved challenging, however, which makes a recently agreed collaboration between CERN and UK firm Paragraf on graphene-based Hall-probe sensors especially novel.

There is probably no other facility in the world to be able to confirm this, so the project has been a big win on both sides, Ellie Galanis

With particle accelerators requiring large numbers of normal and superconducting magnets, high-precision and reliable magnetic measurements are essential. While the workhorse for these measurements is the rotating-coil magnetometer with a resolution limit of the order of 10–8 Vs, the most important tool for local field mapping is the Hall probe, which passes electrical current proportional to the field strength when the sensor is perpendicular to a magnetic field. 

However, measurement uncertainties in the 10–4 range required for determining field multipoles are difficult to obtain, even with the state-of-the-art devices. False signals caused by non-perpendicular field components in the three-dimensional sensing region of existing Hall probes can increase the measurement uncertainty, requiring complex and time-consuming calibration and processing to separate true signals from systematic errors. With an active sensing component made of atomically thin graphene, which is effectively two-dimensional, a graphene-based Hall probe in principle suffers negligible planar Hall effects and therefore could enable higher precision mapping of local magnetic fields.

Inspiration strikes
Stephan Russenschuck, head of the magnetic measurement section at CERN, spotted the potential of graphene-based Hall probes when he heard about a talk given by Paragraf – a recent spin-out from the department of materials science at the University of Cambridge – at a magnetic measurement conference in December 2018. This led to a collaboration, formalised between CERN and Paragraf in April, which has seen several graphene sensors installed and tested at CERN during the past year. 

The firm sought to develop and test the device ahead of a full product launch by the end of this year, and the results so far, based on well-calibrated field measurements in CERN’s reference magnets, have been very promising. “The collaboration has proved that the sensor has no planar effect,” says Paragraf’s Ellie Galanis. “This was a learning step. There is probably no other facility in the world to be able to confirm this, so the project has been a big win on both sides.”

The graphene Hall sensor also operates over a wide temperature range, down to liquid-helium temperatures at which superconducting magnets in the LHC operate. “How these sensors behave at cryogenic temperatures is very interesting,” says Russenschuck. “Usually the operation of Hall sensors at cryogenic temperatures requires careful calibration and in situ cross-calibration with fluxmetric methods. Moreover, we are now exploring the sensors on a rotating shaft, which could be a breakthrough for extracting local, transversal field harmonics. Graphene sensors could get rid of the spurious modes that come from nonlinearities and planar effects.”

CERN and Paragraf, which has patented a scalable process for depositing two-dimensional materials directly onto semiconductor-compatible substrates, plan to release a joint white paper communicating the results so far and detailing the sensor’s performance across a range of magnetic fields.

Tags:  CERN  Ellie Galanis  Graphene  Paragraf  Sensors  Stephan Russenschuck 

Share |
PermalinkComments (0)
 
Page 4 of 63
1  |  2  |  3  |  4  |  5  |  6  |  7  |  8  |  9  >   >>   >|