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

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)
 

Pitt Engineer Maintains a Laser Focus to Grow Nanocarbons on Flexible Devices

Posted By Graphene Council, Wednesday, June 17, 2020
Fabrication of flexible and wearable electronics often requires integrating various types of advanced carbon nanomaterials - such as graphene, nanotubes, and nanoporous carbon - because of their remarkable electrical, thermal, and chemical properties. However, the extreme environments needed to chemically synthesize these nanomaterials means they can only be fabricated on rigid surfaces that can withstand high temperatures. Printing already-made nanocarbons onto flexible polymeric materials is generally the only option, but limits the potential customization.

To overcome this limitation, researchers at the University of Pittsburgh Swanson School of Engineering are investigating a new scalable manufacturing method for creating customizable types of nanocarbons on-demand - directly where they are needed - on flexible materials.

The research is led by Mostafa Bedewy, assistant professor of industrial engineering at Pitt, who received a $244,748 EAGER award from the National Science Foundation in support of this effort. The project, “Transforming Flexible Device Manufacturing by Bottom-up Growth of Nanocarbons Directly on Polymers,” will enable patterning functional nanocarbons needed for a number of emerging flexible-device applications in healthcare, energy, and consumer electronics.

Bedewy’s group is already working on another NSF-funded project that utilizes a custom-designed reactor to grow “nanotube forests” through a process called chemical vapor deposition (CVD). This enables the synthesis of carbon nanotubes from catalyst nanoparticles by the decomposition of carbon-containing gases. The process, however, is not suitable for growing nanocarbons directly onto commercial polymers.

“When we grow nanocarbons by CVD on silicon, it requires temperatures exceeding 700 degrees Celsius, in the presence of hydrocarbon gases and hydrogen,” explained Bedewy, who leads the NanoProduct Lab in the Swanson School's Department of Industrial Engineering. “While silicon can tolerate those conditions, polymers can’t, so CVD is out of the question.”

Instead, Bedewy’s group will utilize a laser in a similar way that common laser engraving machines function. When manufacturing flexible devices, current methods of printing carbon on polymers are limited in scalability and patterning resolution. This new laser-based method addresses these limitations. 

Rather than printing graphene from graphene ink, nanotubes from nanotube ink, and so on, the polymer material itself will act as the carbon source in the new process, and different types of nanocarbons can then grow from the polymer, like grass in a lawn - but instead of using sunlight, through a controlled laser.

“This approach allows us to control the carbon atomic structure, nanoscale morphology, and properties precisely in a scalable way,” said Bedewy. “Our research provides a tremendous opportunity to rapidly customize the type of nanocarbon needed for different devices on the same substrate without the need for multiple inks and successive printing steps.”

Producing functional nanocarbons in this manner will also enable high-rate roll-to-roll processing, which can potentially make manufacturing flexible electronics as fast and as inexpensive as printing newspapers.

“The multi-billion dollar global market for flexible electronics is still in its infancy, and is expected to grow exponentially because of accelerating demand in many applications,” Bedewy said “Exploring potentially transformative carbon nanomanufacturing processes is critical for realizing cutting-edge technologies.”

Tags:  Chemical Vapour Deposition  Electronics  Graphene  Mostafa Bedewy  nanomaterials  polymer  University of Pittsburgh 

Share |
PermalinkComments (0)
 

UT Projects Win $23.6M in R&D Funds as Part of Portuguese Government Technology Program

Posted By Graphene Council, Wednesday, June 10, 2020
The UT Austin Portugal program, a 13-year-old innovation partnership between the university and the Portuguese government, received $23.6 million in funding to pursue 11 R&D projects as part of a major technology initiative from Portugal’s Ministry of Science, Technology and Higher Education.

The projects fall under four major categories: nanomaterials, earth-space interactions, medical physics and advanced computing. The teams will spend the next three years developing their projects, which could transform industries like automotive, space, health care and data science.

“Ranging from electromagnetic interference shielding nanomaterials, to in-beam time-of-flight positron emission tomography for proton radiation therapy, all the way to an ocean and climate change monitoring constellation based on radar altimeter data combined with gravity and ocean temperature and salinity measurements, the spread, number, and quality of the UT Austin Portugal joint strategic projects selected for funding within the recent competitive solicitation set forth by the Foundation for Science and Technology and National Innovation Agency are truly outstanding,” said Manuel Heitor, Portugal’s Minister of Science, Technology and Higher Education. “I look forward to witnessing the results of such collaborative research between Portuguese and UT researchers.”

The call for proposals included just three universities: The University of Texas at Austin, Carnegie Mellon University and the Massachusetts Institute of Technology. UT won the majority of the investment dollars, about 40% of the funding, and saw the most projects funded among the three engineering powerhouses.

“We had anticipated four to five projects would be selected for strategic grant awards and were astounded when we learned 11 had been selected by the evaluation panel in Portugal,” said John Ekerdt, Cockrell School associate dean for research and principal investigator for UT Austin Portugal. “This is a testament to the outstanding faculty and quality projects they proposed with collaborators in Portugal and to the close ties that have been forged between UT researchers and faculty and counterparts in Portugal.”

“The performance of the UT Austin Portugal program in the 2019 call for strategic projects has been remarkable,” said Marco Bravo, executive director of the UT Austin Portugal program. “Eleven of 14 project proposals submitted by the UT Austin Portugal research consortia were approved for funding through an independent assessment process. Overall, UT Austin Portugal saw 11 of its groundbreaking, industry-led proposals approved out of a total of 25 projects approved at this solicitation that included proposals from two other international partnerships, corresponding to nearly $24 million over three years. That’s 40% of total funding to UT Austin Portugal projects, the largest share of research dollars available. UT Austin researchers are to be congratulated on this effort.”

The UT Austin Portugal program dates back to 2007, and it is one of several partnerships between the Portuguese government and research institutions. The goal is to elevate science and technology in Portugal while fostering strong partnerships to help universities continue to innovate. The partnership with UT was extended in 2018, continuing the alliance until at least 2030.

“Of the three international partnerships with American universities sponsored by the Portuguese Foundation for Science and Technology in Portugal, the partnership with UT Austin had the best performance in this call, which was designed and launched on the Portuguese side,” said José Manuel Mendonça, national director of the program. “The 11 approved projects represent a proposal success rate of almost 80% for the UT Austin Portugal Program. The approved projects will, undoubtedly, contribute to promoting and strengthening collaborations with UT Austin in high-level R&D matters with immediate transposition to various sectors of economic activity, several of which are critical to Portugal's competitive position at an international level.”

About a third of the funds for UT’s projects come from the university, with the rest coming from a combination of public and private Portuguese entities. Each project team in Portugal is led by a Portuguese company. The UT side includes 21 faculty members and one from the MD Anderson Cancer Center.

Here is a look at the UT projects:

Shielding electronic devices from electromagnetic interference
This project proposes to use the “wonder material” graphene to improve on methods to combat electromagnetic interference, which can disrupt circuits and cause devices to fail. The team plans to create two composites with electromagnetic interference shielding capabilities and fabricate a solution to protect electric wires used in the automotive industry.

UT Austin Faculty: Deji Akinwande, Cockrell School of Engineering, Department of Electrical and Computer Engineering; Brian Korgel, Cockrell School of Engineering, McKetta Department of Chemical Engineering

New lasers for next-generation biomedical imaging
The use of multiphoton microscopy to examine cell behavior in live tissue over time has become an important research tool for learning more about brains and tumors. This project aims to increase the speed and depth of this form of imaging and diagnostics through the development and application of ultrashort laser pulses.

UT Austin Faculty: Andrew Dunn, Cockrell School of Engineering, Department of Biomedical Engineering; Adela Ben-Yakar, Cockrell School of Engineering, Walker Department of Mechanical Engineering

Nano-satellites for gravitational field assessment
Researchers propose to develop a nano-satellite prototype for studying gravitational fields. The project will also develop a platform for future nano-satellite capabilities, including Earth observation, communications and exploration missions.

UT Austin Faculty: Byron Tapley, Cockrell School of Engineering, Department of Aerospace Engineering and Engineering Mechanics, and the Center for Space Research; Brandon Jones, Cockrell School of Engineering, Department of Aerospace Engineering and Engineering Mechanics, and the Texas Spacecraft Laboratory

Software to match big data with high-performance computing
The advancement of technology has generated huge troves of data, which requires stronger computing power to process and analyze all that information. This project aims to create a software bundle to help companies pair their big data operations with high-performance computing, which includes tools for managing challenges such as computing and research storage.

UT Austin Faculty: Vijay Chidambaram, College of Nature Sciences, Department of Computer Science; Todd Evans, Texas Advanced Computing Center

Sensors for monitoring cancer patients
This project will develop a biosensor that can be injected into prostate cancer patients after surgery. The minimally invasive sensor would allow medical personnel to monitor high-risk patients remotely and look for the development of early tumors, with the potential to increase the predictive value of cancer screenings.

UT Austin Faculty: Thomas Milner, Cockrell School of Engineering, Department of Biomedical Engineering; James Tunnell, Cockrell School of Engineering, Department of Biomedical Engineering

Wearable rehabilitation devices
Researchers will develop a series of nano-sensors embedded into clothing that administer electrostimulation to people suffering from a lack of mobility and motor deficiency. The sensors could be monitored remotely by health professionals, creating a mobile rehabilitation option for people who have trouble getting to a doctor’s office consistently or want greater freedom to complete treatment anywhere. The team envisions its project as a tool mostly for elderly people, but it has applications for training high-level athletes as well.

UT Austin Faculty: George Biros, Cockrell School of Engineering, Walker Department of Mechanical Engineering, and the Oden Institute for Computational Engineering and Sciences; Michael Cullinan, Cockrell School of Engineering, Walker Department of Mechanical Engineering

Software for gathering better data on manufacturing
Getting reliable data on manufacturing processes proves challenging due to issues with placing sensors in the right spots and retaining strong connectivity. Thin films loaded with small sensors that can be applied directly to the equipment represent a promising solution; however, installation has proved difficult. This project proposes a new set of software to make it easier to layer these films on top of equipment by providing necessary data to avoid mechanical problems during installation.

UT Austin Faculty: Rui Huang, Cockrell School of Engineering, Department of Aerospace Engineering and Engineering Mechanics, Center for Mechanics of Solids, Structures and Materials; Kenneth M. Liechti, Cockrell School of Engineering, Department of Aerospace Engineering and Engineering Mechanics, Center for Mechanics of Solids, Structures and Materials

A new way to measure next-generation cancer therapy
Proton radiation therapy, the use of protons rather than X-rays to treat cancer patients, is on the rise, but measuring the distance protons travel proves problematic. Typically, it takes a ring of detectors surrounding the patient to get accurate measurements, but that poses geometric challenges. This project proposes to develop a new type of Positron Emission Tomography scan, which shows how tissues and organs are functioning to better understand the range of protons and whether they are traveling to the right spots to attack the cancer.

UT Faculty: Karol Lang, College of Natural Sciences, Department of Physics; Narayan Sahoo, University of Texas MD Anderson Cancer Center, Department of Radiation Physics

Satellite constellations for monitoring climate change
This project aims to develop the next generation of radar altimeter instruments — which measure the distance between an aircraft and the terrain below it — and a series of small satellites that can understand long-term variability in local, regional and global climate created by changes in sea levels due to water temperature. The project also includes a data processing and visualization system using advanced modeling, estimation techniques, statistical and scientific machine learning methods and error analysis.

UT Austin Faculty: Byron Tapley, Cockrell School of Engineering, Department of Aerospace Engineering and Engineering Mechanics Department, and the Center for Space Research; Patrick Heimbach, Jackson School of Geosciences, Department of Geological Sciences, and the Oden Institute for Computational Engineering and Sciences

Improving cutting tools for airline and automotive components
Fabricating parts of cars and planes is hard on cutting tools and tends to ware them down. This project aims to develop coatings that better protect and extend the lifespan of these crucial pieces of equipment. The team also plans to develop simulation programs to improve cutting tools’ performance.

UT Austin Faculty: Gregory J. Rodin, Cockrell School of Engineering, Department of Aerospace Engineering and Engineering Mechanics, and the Oden Institute for Computational Engineering and Sciences; Filippo Mangolini, Cockrell School of Engineering, Walker Department of Mechanical Engineering

An alternative to traditional water treatment options
Traditional water treatment tech struggles to efficiently remove high amounts of pollutants from some types of surface and groundwater. This team is looking to use metallic nanoparticles to clean water by improving a process called catalytic hydrogenation, which involves adding hydrogen via a metallic catalyst.

UT Austin Faculty: Charles J. Werth, Cockrell School of Engineering, Department of Civil, Architectural, and Environmental Engineering; Simon M. Humphrey, College of Natural Sciences, Department of Chemistry

Tags:  Biomedical  Carnegie Mellon University  Electronics  Environment  Graphene  Healthcare  John Ekerdt  Marco Bravo  Massachusetts Institute of Technology  nanomaterials  Sensors  The University of Texas at Austin  Water Purification 

Share |
PermalinkComments (0)
 

Nanomaterial bests all others in blocking speeding projectiles

Posted By Graphene Council, Tuesday, May 26, 2020
University of Wisconsin–Madison engineers have fabricated a rubbery nanomaterial that outperforms all other materials, including steel and Kevlar, in protecting against high-speed projectile impacts.

The research provides insights for using nanostructured polymers to develop lightweight, high-performance armor. In the future, these new types of armor could potentially be used as a shield on military vehicles to provide enhanced protection from bullets, as well as on spacecraft to mitigate impacts from meteorite debris.

Ramathasan Thevamaran, a professor of engineering physics at UW–Madison, and postdoctoral research associate Jizhe Cai made ultrathin films only 75 nanometers thick out of a relatively common polymer with a nearly impenetrable name — semicrystalline poly(vinylidene fluoride-co-trifluoroethylene) — and demonstrated that the material was superior at dissipating energy from microprojectile impacts over a wide range of velocities.

They detailed their research in a paper published in the journal Nano Letters.

Materials can exhibit different properties at the nanoscale than at larger sizes. This allows researchers to potentially improve specific properties of a material by working with it at extremely small sizes.

“When we shrunk the polymer down to this nanometer length scale, we found that its internal microstructure completely changed in an unexpected fashion compared to its larger scale,” Thevamaran says. “Surprisingly, the energy-absorbing mechanisms in the material became very prominent, and we found that this particular polymer was performing significantly better than any other material—both large materials and previously reported nanomaterials—at absorbing energy from the projectiles.”

To test their ultrathin polymer films, the researchers used a unique experimental technique called micro-ballistic impact testing. They launched projectile particles of about 10 microns (roughly one-tenth the width of a human hair) in size at the polymer film at velocities ranging from 300 feet per second to 3,500 feet per second — several times the speed of a bullet.

Cai and Thevamaran used an ultrafast imaging system to capture images of the projectiles as they penetrated the polymer film, and then they calculated the penetration energy — the amount of kinetic energy from the projectile that was absorbed by the material, per kilogram of the material.

“We normalized the penetration energy values, which allows us to make comparisons between the performance of these polymer films and different material systems,” Thevamaran says.

In addition, Cai and Thevamaran used scanning electron microscopy techniques to study how the material deformed during and after impact. They observed that the impacts caused extensive stretching and deformation in the material, similar to how a piece of rubber can stretch and snap back into shape.

“The key reason this material is performing better across the broad spectrum of velocity is because of its elastic nature in room temperature,” Thevamaran says. “The organization of the material’s internal structure enables ample stretching and deformation mechanisms, which enhance its ability to dissipate energy.”

Maybe not so much for people, though: Thevamaran says the rubbery nature of this material would make it challenging to use for applications like bulletproof vests, because impacts from bullets would protrude into the material and potentially cause blunt trauma injuries to the wearer.

Instead, Thevamaran says this material could be suitable for developing so-called “ambient armor,” where the armor shields the target, but isn’t applied directly to it.

“For example, with ambient armor positioned a short distance from a spacecraft, meteorite debris would first have to penetrate through several layers of this armor, which would dissipate almost all the energy before the projectile strikes the spacecraft, greatly minimizing any damage,” he says.

Thevamaran says the next steps in this research include further scaling up the material and the projectile sizes.

“We want to test a multi-layered system to make sure the novel properties we discovered in micro-ballistics can still be exploited for performance at a larger scale,” he says.

Tags:  Graphene  Jizhe Cai  Journal Nano Letters  nanomaterials  Ramathasan Thevamaran  University of Wisconsin-Madison 

Share |
PermalinkComments (0)
 

Pretty as a peacock: The gemstone for the next generation of smart sensors

Posted By Graphene Council, Tuesday, May 19, 2020
An international team of scientists, led by the Universities of Surrey and Sussex, has developed colour-changing, flexible photonic crystals that could be used to develop sensors that warn when an earthquake might strike next.

The wearable, robust and low-cost sensors can respond sensitively to light, temperature, strain or other physical and chemical stimuli making them an extremely promising option for cost-effective smart visual sensing applications in a range of sectors including healthcare and food safety. 

In a study published by the journal Advanced Functional Materials, researchers outline a method to produce photonic crystals containing a minuscule amount of graphene resulting in a wide range of desirable qualities with outputs directly observable by the naked eye.

Intensely green under natural light, the extremely versatile sensors change colour to blue when stretched or turn transparent after being heated.

Dr. Izabela Jurewicz, Lecturer in Soft Matter Physics at the University of Surrey’s Faculty of Engineering and Physical Sciences, said “This work provides the first experimental demonstration of mechanically robust yet soft, free-standing and flexible, polymer-based opals containing solution-exfoliated pristine graphene. While these crystals are beautiful to look at, we’re also very excited about the huge impact they could make to people’s lives.”

Alan Dalton, Professor Of Experimental Physics at the University of Sussex’s School of Mathematical and Physical Sciences, said: ““Our research here has taken inspiration from the amazing biomimicry abilities in butterfly wings, peacock feathers and beetle shells where the colour comes from structure and not from pigments. Whereas nature has developed these materials over millions of years we are slowly catching up in a much shorter period.”

Among their many potential applications are:

Time-temperature indicators (TTI) for intelligent packaging – The sensors are able to give a visual indication if perishables, such as food or pharmaceuticals, have experienced undesirable time-temperature histories. The crystals are extremely sensitive to even a small rise in temperature between 20 and 100 degrees C.

Finger print analysis - Their pressure-responsive shape-memory characteristics are attractive for biometric and anti-counterfeiting applications. Pressing the crystals with a bare finger can reveal fingerprints with high precision showing well-defined ridges from the skin.

Bio-sensing – The photonic crystals can be used as tissue scaffolds for understanding human biology and disease. If functionalised with biomolecules could act as highly sensitive point-of-care testing devices for respiratory viruses offering inexpensive, reliable, user-friendly biosensing systems.

Bio/health monitoring – The sensors mechanochromic response allows for their application as body sensors which could help improve technique in sports players.

Healthcare safety – Scientists suggest the sensors could be used in a wrist band which changes colour to indicate to patients if their healthcare practitioner has washed their hands before entering an examination room.

The research draws on the Materials Physics Group’s (University of Sussex) expertise in the liquid processing of two-dimensional nanomaterials, Soft Matter Group's (University of Surrey) experience in polymer colloids and combines it with expertise at the Advanced Technology Institute in optical modelling of complex materials. Both universities are working with the Sussex-based company Advanced Materials Development (AMD) Ltd to commercialise the technology.

Joseph Keddie, Professor of Soft Matter Physics at the University of Surrey, said: “Polymer particles are used to manufacture everyday objects such as inks and paints. In this research, we were able finely distribute graphene at distances comparable to the wavelengths of visible light and showed how adding tiny amounts of the two-dimensional wonder-material leads to emerging new capabilities.” 

John Lee, CEO of Advanced Materials Development (AMD) Ltd, said: “Given the versatility of these crystals, this method represents a simple, inexpensive and scalable approach to produce multi-functional graphene infused synthetic opals and opens up exciting applications for novel nanomaterial-based photonics. We are very excited to be able to bring it to market in near future.”

Tags:  2D materials  Advanced Materials Development  Alan Dalton  Graphene  Izabela Jurewicz  John Lee  Joseph Keddie  nanomaterials  photonics  Universities of Surrey  Universities of Sussex 

Share |
PermalinkComments (0)
 

Instantaneous reduction of graphene oxide using electric spark for wearable sensors

Posted By Graphene Council, Monday, May 4, 2020
Wearable electronic devices, worn on clothes or the skin to record body parameters such as heartbeat and pulse rate, are currently in great demand. 2D nanomaterials such as graphene, with their exceptional electrical and mechanical properties, play a key role in fabricating these devices. Graphene oxide (GO) is a scalable and low-cost alternative to pristine graphene. However, GO is an insulator and needs to be reduced to an electrically conducting form called reduced Graphene Oxide (rGO) to make it useful for sensors. 

A group of IISc researchers has now devised a novel method to instantaneously reduce graphene oxide using an electric spark.

This method, outlined in a paper published in ACS Applied Materials and Interfaces, is efficient and cost-effective, which would allow easy industrial scale-up. It is also more environment-friendly compared to existing methods as it does not generate chemical residues. Sensors developed using this method can have applications in gesture control, in biomedical rehabilitation to detect the degree and intensity of body movements, and in the field of robotics. 

Graphene and its derivatives are versatile in their electrical and structural properties, and are therefore the preferred materials used to build flexible sensors. The chemical structure of GO allows it to form ‘printable inks’ with various solvents, and bind to the substrate better. Various reduction techniques, including thermal, UV, laser, and microwave-based methods, are used to modify the chemical structure and form rGO. However, these methods are expensive and time-consuming, often produce toxic by-products, and can also damage the substrate.

To reduce graphene oxide efficiently and quickly, the IISc team used an electrical discharge under ambient conditions, popularly known as an electric spark. Sparking on GO deposited over a porous substrate enables its instantaneous reduction, along with a large drop in electrical resistance.

By varying certain parameters in the spark stream, the team was able to tweak the degree of reduction of graphene oxide, and also make predefined conducting patterns, which offers more flexibility in sensor fabrication. The heat present in the spark is highly localised and does not cause any substrate damage; this was verified using a Scanning Electron Microscope.

When mechanical stress is applied to the rGO-coated fabric, it causes a proportional change in the electrical resistance of the rGO film. This property is essential for it to function efficiently as a flex sensor. The change in electrical resistance was found to be consistent over repeated tests and under different bending angles, says Rajanna Konandur, Honorary Professor at the Department of Instrumentation and Applied Physics, and corresponding author of the paper.

He and his team integrated flex sensors containing these spark-reduced rGO films on commercially available gloves, and tested them using bending and other finger movements. Further research can pave the way for inexpensive, large-scale production of flexible, wearable electronics that use these films.

Tags:  2D materials  Graphene  Graphene Oxide  Indian Institute of Science Bengaluru  Medical  nanomaterials  Rajanna Konandur  Sensors 

Share |
PermalinkComments (0)
 

Alfaisal University: Graphene Research that Breaks the Mould

Posted By Graphene Council, Friday, May 1, 2020
When we talk about technological advancements transforming the way we live, our focus is often on the digital revolution, such as the effects of artificial intelligence and smart technologies. But within physics and chemistry, research into nanomaterials is creating equally profound and important changes in the physical world.

Edreese Alsharaeh, professor of chemistry at Alfaisal University in Saudi Arabia, works with graphene-based composites that are synthesised with nanoparticulate matter to enhance their physiochemical properties. He believes that every aspect of our lives – and almost every product that we use – could be transformed by the application of nanomaterials and likens their discovery to the synthesis of the first polymers. “Almost 100 years ago, the use of polymers had a major, major impact on our daily life,” he says. “We replaced steel. We replaced aluminium. We preserved a lot of natural resources. Nanomaterials nowadays are like polymers 100 years ago. In my line of work, it is the synergetic effect when adding a small percentage of this graphene into the polymer that can do magic.”

Of course, there is no magic, but nanomaterials are perhaps as close to sorcery as contemporary chemistry gets. As Professor Alsharaeh explains, nanomaterials have an inordinately high surface-to-volume ratio compared with materials composed of larger particles, and are thus more reactive, with nano-enhanced materials dramatically more efficient in their design. In some respects, nanotechnology builds on the fundamentals already established by the physical sciences, such as Professor Alsharaeh’s work with graphene and silver composites.

Silver has antimicrobial physiochemical properties capable of killing a wide range of bacteria and fungi, which is why wound dressings often incorporate it as a means of reducing the risk of infection. But by using graphene and silver nanocomposites, these antimicrobial properties can be achieved using far less silver. This, explains Professor Alsharaeh, is a “synergetic effect” that can make a graphene composite with 5 per cent of silver nanoparticles behave with the same antimicrobial properties as 100 per cent silver. Because graphene is flexible, these composites can be used in biomedical contexts such as engineering next-generation bone cement for hip surgery, where infection can be a major cause of morbidity, because the physical demands placed on hips require super-durable orthopaedic solutions.

“We need a product that can stop clinical problems such as infection when you do implants,” says Professor Alsharaeh. “We chose the silver and the graphene because graphene is stronger than steel yet elastic. In our product, the toughness increases 70 per cent and the elasticity is increased by 150 per cent, all from adding 2 per cent graphene.”

With multiple drug resistant bacteria increasingly a problem, finding novel strategies for combatting hospital infections is also a priority for medical science. This is an area where the antimicrobial properties of both graphene and silver might provide the answer; and so it is the focus of extensive research at Professor Alsharaeh’s lab, where graphene and silver have been found to be effective in disinfecting MDR bacteria and E. coli, with the electronic structure of graphene in particular inhibiting bacteria growth. Everyday medical apparatus could incorporate nanocomposites of graphene and silver to stop the spread of infection.

“This composite is very good for coating biomedical devices, which is something that is a major deal when you use a catheter, for example,” says Professor Alsharaeh. “People are [developing an] infection and I think when we coat [devices] with some kind of material like this, that will change. This is in our product development phase now, in addition to the bone cement. Graphene has the potential to revolutionise nanocomposite materials. That it can be anchored with any number of nanoparticles only enhances its versatility and increases the number of real-world applications it could be used for. It is strong, flexible and thermoconductive. “You can make any device out of it,” says Professor Alsharaeh. “It can be used as a substrate for multifunctional properties.”

As he explains, graphene’s structure – with carbon atoms bonded in a flat, hexagonal lattice – is key. Because it is a two-dimensional structure, it restricts electrons to movements along an X or Y axis, and this confinement creates energy that endows graphene with useful optical and electronic properties. “Its electronic properties are actually one of the most attractive things about the graphene,” says Professor Alsharaeh, who adds that graphene can conduct electricity up to 150 times faster than silicon, and be used for superconductors and to manufacture dramatically more efficient integrated circuits for computer processing.

The goal for Professor Alsharaeh’s lab at Alfaisal is to take this research into product development as soon as possible. Besides its medical applications, Alfaisal has a patent with oil and gas giant Saudi Aramco on a graphene-based product that is in the process of commercialisation. “The Kingdom puts a lot of resources in,” says Professor Alsharaeh. “From 2010, since I came to Saudi Arabia…there has been major funding for all scientists, which is a major plan for this energy sector.” With agriculture, medicine, energy and textiles sectors all set to reap the benefits of nanotechnology, the commercial potential of graphene nanocomposites is invaluable.

Professor Alsharaeh adds that he is a chemist, and his passion is for discovery and teaching. “It is very, very rewarding for me to see [that some students] have now finished their PhDs and are making their way in the world,” he says. “This is also about building the culture for future scientists. And I think nanotechnology is the future for all future-first technologies.”

That future will still be shaped by the digital revolution, but when the smart devices in our pockets, homes, workplaces and hospitals are all enhanced by nanomaterials, perhaps that future should be considered a joint venture with nanotechnology.

Tags:  Alfaisal University  Edreese Alsharaeh  Graphene  nanocomposites  nanomaterials  Polymer 

Share |
PermalinkComments (0)
 

Perovskite/graphene nanosensor detects nitrogen dioxide with 300% improved sensitivity

Posted By Graphene Council, Thursday, April 30, 2020
The research team, led by Juan Casanova and Eduard Llobet, belonging to the Departamento de Ingeniería Electrónica, Eléctrica y Automática at the URV, worked with two materials. First, they used graphene, which is very hydrophobic—water and moisture-resistant—and quite sensitive in gas detection, but with some limitations: it is not very selective and its sensitivity declines over time.

Moreover, they used perovskites, a crystalline-structure material commonly used in the field of solar cells. However, they quickly deteriorate when they are exposed to the atmosphere. That's the reason why they decided to combine perovskites with a hydrophobic material able to repel water molecules such as graphene, in order to prove they can prevent or slow down their deterioration.

"This graphene and perovskites hybrid resulted in a material that can more sensitively detect these kinds of gas. Perovskite alone eventually deteriorates and we have proved that when we put it on top of graphene, their properties and the sensor response remain stable longer," explains Eduard Llobet.

Carbon nanomaterials sensors, a promising future
Researchers have worked for years looking for alternatives to conventional sensors and the carbon nanomaterials field offers promising results in this area. Besides being tiny and needing very low energy for functioning, these materials have proven to have good responses and quick recovery at room temperature, unlike existing sensors.

"They are portable devices due to their size—they can be even wearable. Work at room temperature is very important because they need very small batteries, an unthinkable feature with other materials," says Llobet.
This research has used graphene with perovskite nanocrystals as a toxic gas sensor for the first time and it has proved this combination is a good alternative to detect these compounds due to its high sensitivity over time.

Thanks to the results of this study (Sensors, "Gas Sensing Properties of Perovskite Decorated Graphene at Room Temperature"), perovskites have become an alternative to metals, metal oxides, polymers and other molecules frequently used to modify the surfaces of carbon nanomaterials such as graphene.

The ITQ research team has worked for years in several lines aimed at the synthesis and application of perovskites in fields such as solar cells and photocatalysts. However, their use as sensors is relatively new. ITQ carried out the size and composition control of nanocrystals to make them highly sensitive to nitrogen dioxide.

“These materials present a high potential to develop new gas sensors, because here we take advantage of a limitation in the field of solar cells: "defects" that in the case of sensors play a significant role in the functioning mechanism. In addition, taking into account all the structural modification possibilities of perovskites, we have the opportunity to find a large family of sensors to detect other gases. Also, it is important to note that perovskites are easy to synthesize and they use abundant elements in nature," explains Pedro Atienzar, CSIC scientist at the Instituto de Tecnología Química.

Tags:  Eduard Llobet  Graphene  Instituto de Tecnología Química  nanomaterials  Pedro Atienzar  Sensors 

Share |
PermalinkComments (0)
 

ZEN Graphene Solutions Announces Collaboration with Graphene Composites Ltd. to Develop a COVID-19 Virucidal Graphene-Based Composite Ink for Face Masks

Posted By Graphene Council, Thursday, April 30, 2020
ZEN Graphene Solutions Ltd. is pleased to announce an international collaboration with UK-based Graphene Composites Ltd (GC) to fight COVID-19 by developing a potential virucidal graphene-based composite ink that can be applied to fabrics including N95 face masks and other personal protective equipment (PPE) for significantly increased protection. Once the development, testing, and confirmation of the graphene ink’s virucidal ability have been completed, the ink will then be incorporated into fabrics used for PPE.

Francis Dubé, CEO of ZEN commented, “We are pleased to be collaborating with GC and be on the forefront of a new innovative technology that could contribute to combating the deadly COVID-19 virus. The development of this potential COVID-19 virucidal graphene ink is coming at a crucial time to provide effective PPE supplies for the safety of frontline workers and hospital staff.” Dr. Dubé continued, “The current N95 masks trap the virus but don’t kill it. Our testing will demonstrate if the graphene ink is an effective virucide which would kill the virus as this could make a big difference to people’s safety. We have been very impressed by the Graphene Composites team and look forward to continued collaborations.”

Sandy Chen, CEO of GC stated, “Combining the deep nanomaterials expertise of GC and ZEN with a truly collaborative approach has enabled us to do a year’s worth of R&D in a matter of weeks. Quickly developing and deploying our virucidal/germicidal ink would make a significant difference in slowing the rate of infection – thus saving many lives.”

Under the collaboration, ZEN has synthesized a silver nanoparticles functionalized graphene oxide ink at their lab in Guelph, Ontario that has been documented by previous researchers to kill earlier versions of coronavirus. Once testing is completed, the ZEN/GC graphene ink would then be incorporated into a fabric to be included into masks and filters designed by GC.

Efficacy testing of the silver-graphene oxide-based ink to kill the COVID 19 virus (SARS-CoV-2) will be conducted at Western University’s ImPaKT Facility Biosafety Level 3 lab in Ontario. In addition, the graphene ink will be tested to kill influenza A and B viruses at Biosafety Level 2 labs in the UK and US.

Tags:  Francis Dubé  Graphene  Graphene Composites  graphene oxide  nanomaterials  Sandy Chen  ZEN Graphene Solutions 

Share |
PermalinkComments (0)
 

COVID-19 is a chronic disease – and cancer care model is way forward, says Manchester expert

Posted By Graphene Council, Tuesday, April 28, 2020
As the UK government looks for an exit strategy to the COVID-19 lockdown a nanomedicine expert from The University of Manchester believes a care model usually applied to cancer patients could provide a constructive way forward.

Kostas Kostarelos, is Professor of Nanomedicine at The University of Manchester and is leading the Nanomedicine Lab, which is part of the National Graphene Institute and the Manchester Cancer Research Centre.

The Manchester-based expert believes more scientific research should be employed as we transform how we view the COVID-19 pandemic, or any future virus outbreak, and deal with it more like a chronic disease - an ever present issue for humanity that needs systematic management if we are ever to return to our ‘normal’ lives.

Professor Kostarelos makes this claim in an academic thesis entitled 'Nanoscale nights of COVID-19' that offers a nanoscience response to the COVID-19 crisis and will be published on Monday, April 27, by the journal Nature Nanotechnology.

“As for any other chronic medical condition, COVID-19 stricken societies have families, jobs, businesses and other commitments. Therefore, our aim is to cure COVID-19 if possible,” says Professor Kostarelos.

“However, if no immediate cure is available, such as effective vaccination,” Professor Kostarelos suggests: “We need to manage the symptoms to improve the quality of patients’ lives by making sure our society can function as near as normal and simultaneously guarantee targeted protection of the ill and most vulnerable.”

As for any other chronic medical condition, COVID-19 stricken societies have families, jobs, businesses and other commitments. Therefore, our aim is to cure COVID-19 if possible. However, if no immediate cure is available, such as effective vaccination we need to manage the symptoms to improve the quality of patients’ lives by making sure our society can function as near as normal and simultaneously guarantee targeted protection of the ill and most vulnerable Professor Kostas Kostarelos.

Professor Kostarelos says his experience in cancer research and nanotechnology suggests a model that could also be applied to a viral pandemic like COVID-19.

“There are three key principles in managing an individual cancer patient: early detection, monitoring and targeting,” explains Professor Kostarelos. “These principles, if exercised simultaneously, could provide us with a way forward in the management of COVID-19 and the future pandemics.

“Early detection has improved the prognosis of many cancer patients. Similarly, early detection of individuals and groups, who are infected with COVID-19, could substantially accelerate the ability to manage and treat patients.

“All chronic conditions, such as cancer, are further managed by regular monitoring. Therefore, monitoring should be undertaken not only for patients already infected with COVID-19, to track progression and responses, but also for healthy essential workers to ensure that they remain healthy and to reduce the risk of further spreading.

Finally, says Professor Kostarelos, nanomaterials - as well as other biologicals, such as monoclonal antibodies - are often used for targeting therapeutic agents that will be most effective only against cancer cells.

The same principle of ‘targeting’ should be applied for the management of COVID-19 patients to be able to safely isolate them and ensure they receive prompt treatment.

Also, a safeguarding strategy should be provided to the most vulnerable segments of the population by, for example, extending social distancing protocols in elderly care homes - but with the provision of emotional and practical support to ensure the wellbeing of this group is fully supported.

“Protection of the most vulnerable and essential workers, must be guaranteed, with protective gear and monitoring continuously provided,” he added. “Only if all three principles are applied can the rest of society begin to return to normal function and better support the activities in managing this and all future pandemics.”

Tags:  Graphene  Healthcare  Kostas Kostarelos  nanomaterials  nanotechnology  University of Manchester 

Share |
PermalinkComments (0)
 
Page 1 of 5
1  |  2  |  3  |  4  |  5