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

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)
 

Eavesdropping on single molecules with light by replaying the chatter

Posted By Graphene Council, Wednesday, May 6, 2020
The structure of individual molecules and their properties, such as chirality, are difficult to monitor in real time. It turns out that by temporarily bridging molecules together we can provide a lens into their dynamics.

A study led by Prof. Frank Vollmer at the University of Exeter’s Living Systems Institute has exposed new pathways for investigating biochemical reactions at the nanoscale. Thiol/disulfide exchange at equilibrium has not yet been fully scrutinised at the single-molecule level, in part because this cannot be optically resolved in bulk samples.

Light can, however, circulate around micron-sized glass spheres to form resonances. The trapped light can then repeatedly interact with its surrounding environment. By attaching gold nanoparticles to the sphere, light is enhanced and spatially confined down to the size of viruses and amino acids.

The resulting optoplasmonic coupling allows for the detection of biomolecules that approach the nanoparticles while they attach to the gold, detach, and interact in a variety of ways.

Despite the sensitivity of this technique, there is lacking specificity. Molecules as simple as atomic ions can be detected and certain dynamics can be discerned, yet we cannot necessarily discriminate them.

The breakthroughs reported in Nature Communications ("Optoplasmonic characterisation of reversible disulfide interactions at single thiol sites in the attomolar regime") have proceeded to amend this.

Reaction pathways regulated by disulfide bonds can constrain interactions to single thiol sensing sites on the nanoparticles. The high fidelity of this approach establishes precise probing of the characteristics of molecules undergoing the reaction.

By placing linkers on the gold surface, interactions with thiolated species are isolated for based on their charge and the cycling itself.

Sensor signals have clear patterns related to whether reducing agent is present. If it is, the signal oscillates in a controlled way, while if it is not, the oscillations become stochastic. For each reaction the monomer or dimer state of the leaving group can be resolved.

Surprisingly, the optoplasmonic resonance shifts in frequency and/or changes in linewidth when single molecules interact with it. In many cases this result suggests a plasmon-vibrational coupling that could help identify individual molecules, finally achieving characterisation.

"This excellent work by my PhD student, Serge Vincent, paves the way for many future single-molecule analysis techniques that we have only been dreaming about," Professor Frank Vollmer adds. "It is a crucial step for our project ULTRACHIRAL. ULTRACHIRAL seeks to develop breakthroughs in how we use light to analyse chiral molecules."

Tags:  Frank Vollmer  Graphene  nanoparticles  Sensors  University of Exeter 

Share |
PermalinkComments (0)
 

IIT Guwahati research team develops hierarchically structured graphene oxide nanosheets that can selectively separate oily or aqueous contaminates from respective emulsions

Posted By Graphene Council, Thursday, April 23, 2020
Researchers of Indian Institute of Technology Guwahati have developed a graphene-based superhydrophobic materials that can separate oil and water from both oil-in-water and water-in-oil emulsions, respectively.

Their work has recently been published in the Royal Society’s journal, Chemical Science. The research paper has been authored by Dr. Uttam Manna, Associate Professor, Department of Chemistry, IIT Guwahati, along with his research scholars Mr. Avijit Das, Mr. Kousik Maji, and Mr. Sarajit Naska.

Oil–water separation techniques have a number of industrial and environmental applications. Various porous and bulk substrates such as sponge that are made superhydrophobic, have been used to absorb oil from oil-water emulsions. The IIT Guwahati team has shown the efficacy of hierarchically structured graphene oxide nanosheets in removing oil or aqueous contaminates from respective emulsions, thereby effecting separation of oil and water.
 
Superhydrophobic materials – materials with extreme water repellence – are considered the best materials for removing oil from water, and they are being extensively studied for applications such as water purification and self-cleaning surfaces. The problem with superhydrophobic materials is that they are generally not scalable, or use environmentally toxic products such as fluorinated polymers/small molecules, or have poor mechanical and chemical stability. Moreover, the conventional spongy superhydrophobic materials are inherently less appropriate for separating oil-in-water emulsion due to poor accessibility of the dispersed oil droplets to the oil absorbing superhydrophobic interface.

“The hydrophobicity of materials is largely governed by the physical architecture and the chemical composition, and so such materials can be rationally created by combining low-surface-energy materials with hierarchical roughness”, explains Dr. Manna. This is exactly what the group has done in its quest for oil-water separating materials. They have manipulated graphene, a form of carbon, to have superhydrophobic properties suitable for separation of oil from water in emulsions.

The study of graphene for such applications is not unprecedented. Since the award of the Nobel prize to its creators in 2010, graphene – two dimensional structures of carbon – has been extensively studied for a variety of applications. Composed of pure carbon, graphene is similar to graphite but with characteristics that make it extraordinarily light and strong, giving it a moniker of “wonder material” in present day materials science research. Research all over the world have attempted to engineer the structure and composition of graphene to get surface roughness and low surface energy, suitable for use in applications that require superhydrophobicity. Such engineering is challenging and complicated.

The IIT Guwahati team has developed a facile method to produce graphene oxide-polymer composite with hierarchical topography and low surface energy chemistry in the confined space. Such graphene oxide species showed ‘confined-super- water-repellence’. They further deposited iron oxide nanoparticles on the two dimensional nanosheets, which made the entire material magnetically active.

“Our graphene oxide composites were able to separate oil from water in emulsions with high efficiency” says Dr. Manna. The uniqueness was that the separation could be brought about even under extremes of pH, salinity, surfactant contaminations etc., as is seen in real life scenarios. The IIT Guwahati’s graphene oxide species was capable of selectively soaking up tiny crude-oil droplets in oil-to-water emulsions with high absorption capacity (above 1000 wt%), as well as coalescing larger oil droplets of emulsions from water-in-oil emulsions.

“Further functionalization of this chemically/magnetically active 2D-nano-interface could help in the development of functional interfaces for various applications related to energy, catalysis and healthcare”, says Dr. Manna.

Tags:  2D materials  Graphene  graphene oxide nanosheets  Indian Institute of Technology Guwahati  nanoparticles  Uttam Manna  water purification 

Share |
PermalinkComments (0)
 

Pushing the Limits of 2D Supramolecules

Posted By Graphene Council, Saturday, April 18, 2020
Scientists at the University of South Florida have reached a new milestone in the development of two-dimensional supramolecules – the building blocks that make areas of nanotechnology and nanomaterial advancement possible.

Since the 2004 discovery of graphene, the world’s thinnest (one atom thick) and strongest (200 times stronger than steel) material, researchers have been working to further develop similar nanomaterials for industrial, pharmaceutical and other commercial uses. Thanks to its conductive properties and strength, graphene can be used in microelectronics to fortify mechanical materials and has recently enabled precise 3D imaging of nanoparticles.

 While work to develop new supramolecules capable of further applications has seen some success, those molecular formations are either small – less than 10 nanometers in size – or arbitrarily assemble, limiting their potential use. But now, new research published in "Nature Chemistry," outlines a profound leap forward in supramolecular progress.

“Our research team has been able to overcome one of the major supramolecular obstacles, developing a well-defined supramolecular structure that pushes the 20-nanometer scale,” said Xiaopeng Li, an associate professor in the USF Department of Chemistry and the study’s lead researcher. “It’s essentially a world record for this area of chemistry.”

Li, along with his USF research team, collaborated with Saw Wai Hia’s team at the Argonne National Laboratory and Ohio University, as well as several other U.S. and international research institutes on this effort.

Supramolecules are large molecular structures made up of individual molecules. Unlike traditional chemistry, which focuses on covalent bonds between atoms, supramolecular chemistry studies the noncovalent interactions between molecules themselves. Many times, these interactions lead to molecular self-assembly, naturally forming complex structures capable of performing a variety of functions.

In this latest study, the team was able to build a 20-nm-wide metallo-supramolecular hexagonal grid by combining intra- and intermolecular self-assembly processes. Li says the success of this work will advance further understanding of the design principles governing these molecular formations and could one day lead to the development of new materials with yet-to-be-discovered functions and properties.

Tags:  Argonne National Laboratory  Graphene  nanomaterial  nanoparticles  Ohio University  University of South Florida  Xiaopeng Li 

Share |
PermalinkComments (0)
 

Scientists Capture 3D Images of Nanoparticles, Atom by Atom, With Unprecedented Precision

Posted By Graphene Council, Saturday, April 11, 2020
Since their invention in the 1930s, electron microscopes have helped scientists peer into the atomic structure of ordinary materials like steel, and even exotic graphene. But despite these advances, such imaging techniques cannot precisely map out the 3D atomic structure of materials in a liquid solution, such as a catalyst in a hydrogen fuel cell, or the electrolytes in your car’s battery.

Now, researchers at Berkeley Lab, in collaboration with the Institute for Basic Science (IBS) in South Korea, Monash University in Australia, and UC Berkeley, have developed a technique that produces atomic-scale 3D images of nanoparticles tumbling in liquid between sheets of graphene, the thinnest material possible. Their findings were reported April 3 in the journal Science.

“This is an exciting result. We can now measure atomic positions in three dimensions down to a precision six times smaller than hydrogen, the smallest atom,” said study co-author Peter Ercius, a staff scientist at Berkeley Lab’s Molecular Foundry.

The technique, called 3D SINGLE (Structure Identification of Nanoparticles by Graphene Liquid cell Electron microscopy), employs one of the world’s most powerful microscopes at Berkeley Lab’s Molecular Foundry. The researchers captured thousands of images of eight platinum nanoparticles “trapped” in liquid between two graphene sheets – called a “graphene window.”

These graphene sheets – each one just an atom thick – are “strong enough to contain tiny pockets of liquid necessary to acquire high-quality images of the nanoparticles’ atomic arrangement,” Ercius explained.

The researchers then adapted computer algorithms originally designed for biological studies to combine many 2D images into atomic-resolution 3D images.

The achievement, which improves upon a technique first reported in 2015, marks a significant milestone for the researchers. “With 3D SINGLE, we can determine why such small nanoparticles are more efficient catalysts than larger ones in fuel cells and hydrogen vehicles,” Ercius said.

Tags:  Berkeley Lab  Graphene  Institute for Basic Science (IBS)  Monash University  Nanoparticles  Peter Ercius  University of California Berkeley 

Share |
PermalinkComments (0)
 

UIC physics and mathematics student named Goldwater Scholar

Posted By Graphene Council, Thursday, April 9, 2020

Lopa Bhatt, a UIC Honors College member who is majoring in physics and mathematics in the College of Liberal Arts and Sciences. A University of Illinois at Chicago undergraduate student studying electron microscopy has been recognized for her academic achievement by the Barry M. Goldwater Scholarship and Excellence Foundation.

Lopa Bhatt, a junior majoring in physics and mathematics in the College of Liberal Arts and Sciences, is the latest UIC student to receive the prominent $7,500 scholarship that will cover tuition, books and related fees during the 2020-21 academic year.

Almost 400 recipients in mathematics, science and engineering were selected from an estimated applicant pool of over 5,000 college sophomores and juniors for the Goldwater Scholarship, named for the late Republican senator from Arizona.

Bhatt, a UIC Honors College member from Naperville, has studied in the lab of Robert Klie, UIC professor of physics, where her work has been focused on improving techniques related to the fabrication of graphene-based liquid cells, or GLCs.

“Lopa has learned not only how to operate a state-of-the-art electron microscope, she is also able to perform atomic-resolution imaging and spectroscopy using electron probes that do not damage the delicate graphene liquid cells. This is an extraordinary achievement,” Klie said.

Bhatt is involved in several cutting-edge research projects and will be a co-author on at least three papers, covering a wide range of materials and biomaterials science.

“Previous studies have demonstrated that charged nanoparticles have a wide range of applications, from the treatment of diseases, such as cancer and bacterial infections, to the removal of pollutants from water,” she said. “Nevertheless, much remains unknown about the behavior of charged nanoparticles in aqueous solution, primarily due to the small scale of nanoparticles and the limitations of optical microscopes.”

This inability to quantify the interactions between the liquid and the charged nanoparticles has been a significant barrier to their development and implementation in medical and environmental applications.

“These GLCs can be used to examine solutions through the scanning transmission electron microscope — an instrument that is able to even see the arrangement of atoms in a material,” Bhatt said. “I have been able to improve the GLCs in order to encapsulate the nanoparticles solution and make progress in understanding how the nanoparticles behave in nanoconfined spaces in solutions.”

Last year, she presented research at conferences held by the American Physical Society, Microscopy Society of America and the Oak Ridge National Laboratory.

“Such exposure to the research community is unique for an undergraduate student, and is the result of Lopa’s outstanding research and presentation skills,” Klie said.

Her future academic and professional objectives are to earn a Ph.D. from a top-tier materials science/condensed matter physics program and become a successful researcher or professor focused on electron microscopy.

Bhatt, who was born in India, moved to the U.S. in 2015. She graduated from Metea Valley High School in 2017 and received the President’s Award Program-Honors Scholarship, which is the Honors College’s most prestigious award and covers four-year tuition and housing for exemplary incoming first-year students.

While at UIC, she has received multiple university honors, including the Chancellor’s Undergraduate Research Award, the UIContest Award for Outstanding Undergraduate Researcher and the College of Liberal Arts and Science Undergraduate Research Initiative Award. The Honors College has also awarded her undergraduate conference travel grants and an undergraduate research grant.

In addition to family and friends, Bhatt credits her achievements in part to the support she’s received at UIC from people such as Klie; Andrew Shulman, senior lecturer in mathematics, statistics and computer science, and Mark Schlossman, professor of physics.

“Some of the professors at UIC have had a really big impact on my educational career, and it is because of them that I have gotten this far,” she said.

UIC’s Office of External Fellowships provides advising and assistance to current undergraduate and professional school students in finding and applying for a range of nationally and internationally competitive fellowships, scholarships and grants.

“Lopa’s success in the Goldwater competition — the most prestigious STEM award nationwide for sophomores and juniors involved in research — is a testament to her intellect, dedication and research skills, and it is also evidence of UIC’s strength in providing opportunities and mentoring in and through undergraduate research,” said Kim Germain, director of UIC’s Office of External Fellowships.

Tags:  Graphene  Kim Germain  Lopa Bhatt  nanomaterials  nanoparticles  University of Illinois at Chicago 

Share |
PermalinkComments (0)
 

3D reconstructions of individual nanoparticles

Posted By Graphene Council, Friday, April 3, 2020

What do you see in the picture above (Figure 1)? Merely a precisely-drawn three-dimensional picture of nanoparticles? Far more than that, nanotechnologists will say, due to a new study published in the journal Science. Whether a material catalyzes chemical reactions or impedes any molecular response is all about how its atoms are arranged. The ultimate goal of nanotechnology is centered around the ability to design and build materials atom by atom, thus allowing scientists to control their properties in any given scenario. However, atomic imaging techniques have not been sufficient to determine the precise three-dimensional atomic arrangements of materials in liquid solution, which would tell scientists how materials behave in everyday life, such as in water or blood plasma.

Researchers at the Center for Nanoparticle Research within the Institute for Basic Science (IBS, South Korea), in collaboration with Dr. Hans Elmlund at Monash University's Biomedicine Discovery Institute in Australia and Dr. Peter Ercius at Lawrence Berkeley National Laboratory's Molecular Foundry in the USA, have reported a new analytic methodology that can resolve the 3D structure of individual nanoparticles with atomic-level resolution. The 3D atomic positions of individual nanoparticles can be extracted with a precision of 0.02 nm--six times smaller than the smallest atom: hydrogen. In other words, this high-resolution method detects individual atoms and how they are arranged within a nanoparticle.

The researchers call their development 3D SINGLE (Structure Identification of Nanoparticles by Graphene Liquid cell Electron microscopy) and utilize mathematical algorithms to derive 3D structures from a set of 2D imaging data acquired by one of the most powerful microscopes on Earth. First, a nanocrystal solution is sandwiched in-between two graphene sheets which are each just a single atom thick (Figure 2.1). "If a fish bowl were made of a thick material, it would be hard to see through it. Since graphene is the thinnest and strongest material in the world, we created graphene pockets that allow the electron beam of the microscope to shine through the material while simultaneously sealing the liquid sample," explains PARK Jungwon, one of the corresponding authors of the study (assistant professor at the School of Chemical and Biological Engineering in Seoul National University).

The researchers obtain movies at 400 images per second of each nanoparticle freely rotating in liquid using a high-resolution transmission electron microscope (TEM). The team then applies their reconstruction methodology to combine the 2D images into a 3D map showing the atomic arrangement. Locating the precise position of each atom tells researchers how the nanoparticle was created and how it will interact in chemical reactions.

The study defined the atomic structures of eight platinum nanoparticles - platinum is the most valuable of the precious metals, used in a number of applications such as catalytic materials for energy storage in fuel cells and petroleum refinement. Even though all of the particles were synthesized in the same batch, they displayed important differences in their atomic structures which affect their performance.

"Now it is possible to experimentally determine the precise 3D structures of nanomaterials that had only been theoretically speculated. The methodology we developed will contribute to fields where nanomaterials are used, such as fuel cells, hydrogen vehicles, and petrochemical synthesis," says Dr. KIM Byung Hyo, the first author of the study. Notably, this methodology can measure the atomic displacement and strain on the surface atoms of individual nanoparticles. The strain analysis from the 3D reconstruction facilitates characterization of the active sites of nanocatalysts at the atomic scale, which will enable structure-based design to improve the catalytic activities. The methodology can also contribute more generally to the enhancement of nanomaterials' performance.

"We have developed a groundbreaking methodology for determining the structures that govern the physical and chemical properties of nanoparticles at the atomic level in their native environment. The methodology will provide important clues in the synthesis of nanomaterials. The algorithm we introduced is related to new drug development through structure analysis of proteins and big data analysis, so we are expecting further application to new convergence research," notes Director HYEON Taeghwan of the IBS Center for Nanoparticle Research.

Tags:  Graphene  Hans Elmlund  Healthcare  HYEON Taeghwan  Institute for Basic Science  nanoparticles 

Share |
PermalinkComments (0)
 

High-performance anode for all-solid-state Li batteries is made of Si nanoparticles

Posted By Graphene Council, Tuesday, December 31, 2019
A new study led by NIMS researchers reveals that, in solid electrolytes, a Si anode composed only of commercial Si nanoparticles prepared by spray deposition -- the method is a cost-effective, atmospheric technique -- exhibits excellent electrode performance, which has previously been observed only for film electrodes prepared by evaporation processes. This new result therefore suggests that a low-cost and large-scale production of high-capacity anodes for use in all-solid-state Li batteries is possible.

Si has a theoretical capacity of ~4,200 mAh/g, which is approximately 11 times higher than that of the graphite commonly used as the anode-active material in commercial Li-ion batteries. Replacing the traditional graphite by Si can extend significantly the driving range per charge of electric vehicles. However, its huge volume change (~300%) during lithiation and delithiation -- charge and discharge -- hinders its practical application in the batteries. In conventional liquid electrolytes, the use of polymeric binders is necessary to hold the active material particles in the electrode together and maintain their adhesion to the surface of metal current collectors. The repeated huge volume change of Si causes the particle isolation and thus leads to losing the active material, which results in a continuous capacity loss. In solid-state cells, the active material is placed between two solid components -- solid electrolyte separator layer and metal current collector --, which enables avoidance of tackling the problem -- electrical isolation of the active material --. In fact, as reported previously by the team of NIMS researchers, the sputter-deposited pure Si films delivering practical areal capacities exceeding 2.2 mAh/cm2 exhibit excellent cycling stability and high-rate discharge capabilities in solid electrolytes. Nonetheless, cost-effective and industrially scalable synthesis of the anode for all-solid-state Li batteries remains a great challenge.

The team of NIMS researchers has taken another synthesis approach toward develop the high-performance anode for all-solid-state Li batteries with commercial Si nanoparticles, and found a unique phenomenon to the nanoparticles in the solid-state cell: upon lithiation, they undergo volume expansion, structural compaction, and appreciable coalescence in the confined space between the solid electrolyte separator layer and metal current collector to form a continuous film similar to that prepared by the evaporation process. The anode composed of nanoparticles prepared by spray deposition therefore exhibits excellent electrode performance, which has previously been observed only for sputter-deposited film electrodes. The spray deposition method is a cost-effective, atmospheric technique that can be used for large-scale production. Hence, the findings will pave the way for low-cost and large-scale production of high-capacity anodes for use in all-solid-state Li batteries.

Continuing efforts by the team of NIMS researchers to improve the cyclability in the anode having the increased areal mass loading of nanoparticles are in progress to meet the requirements of electric vehicles.

Tags:  Electric Vehicle  Graphene  Graphite  Li-ion batteries  nanoparticles  National Institute for Materials Science 

Share |
PermalinkComments (0)
 

Using electronics to solve common biological problems

Posted By Graphene Council, Wednesday, December 4, 2019
Researchers from multiple disciplines are working together at KAUST to develop bioelectronics that can detect diseases, treat cancers and track marine animals; they may even discover the next generation of computing systems.

Cancer-killing magnets

Jurgen Kosel is an electrical engineer who loves to play with magnets. His research group has developed a technique to fabricate unique magnetic iron-oxide nanowires that can kill cancer cells1.

“Certain kinds of iron-based magnetic nanoparticles were approved many years ago by the U.S. Food and Drug Administration for use inside the human body. They are regularly used as contrast agents in magnetic resonance imaging and as nutritional supplements for people with iron deficiency,” says Kosel.

The magnetic nanoparticles currently in use are spherical in shape. Kosel and his team developed wire-shaped magnetic nanoparticles that can be rotated like a compass needle, creating a pore in cancer cell membranes that induces natural cell death. These cancer-killing nanowires can be made even more effective when coated with an anti-cancer drug or heated with a laser. They are "eaten" by cancer cells, and once released inside, they can wreak havoc.

Kosel has been working closely with cell biologist Jasmeen Merzaban, and more recently, with organic chemist Niveen Khashab to "functionalize" the surfaces of his magnetic nanowires to ensure the body’s immune system does not treat them as foreign. They are also working on preventing the wires from sticking together and on targeting cancer cells more specifically by coating them with antibodies that recognize specific antigens on their cell membranes.

Kosel has also worked with electrical engineer Muhammad Hussain to use magnets for improving the safety of cardiac catheters. They have developed a flexible magnetic sensor that is sensitive enough to detect the Earth’s magnetic field. When these sensors are placed on the tip of a cardiac catheter, for example, clinicians can detect its orientation inside blood vessels. This enables them to direct it where it is needed in order to insert a stent, for example, to relieve blockage in a heart artery. This reduces the need for prolonged doses of X-rays and contrast dyes during procedures like coronary angioplasty.

Disease detection

“Over the past 50 years, the 500-billion-dollar semiconductor industry has mainly focused on two applications: computing and communications,” says KAUST electrical engineer, Khaled Salama. “But this technology holds a lot of promise for other areas, including medical research, as people are living longer and needing more care. We need a paradigm shift to leverage some of the technologies we’ve developed for use in this area.”

Salama has developed a sensor that can detect "C-reactive proteins," a biomarker of cardiovascular disease2. He’s done this by functionalizing electrodes with nanomaterials and gold nanoparticles to improve their sensitivity. The electrodes give a signal that is proportional to the amount of C-reactive protein in a blood sample. His group developed a unique process that 3D prints the microfluidic channels that deliver samples to the sensor for biological detection.

Elsewhere at KAUST, Sahika Inal is developing a device that can make life easier for diabetics.

Inal comes from a textile manufacturing background, but her studies on the electrical properties of polymers, which are biocompatible, have led her down the route of bioelectronics. 

Her team has developed inkjet-printed, disposable, polymer-based sensors that can measure glucose levels in saliva3. “We inkjet-print conducting polymers. The biological ink contains the enzymes used for glucose sensing, an encapsulation layer that protects the enzymes, a layer that only allows glucose penetration and an insulating layer to protect the electronics,” she explains. “And then you have a paper-based sensor within a few minutes!”

Inal is also developing other biochemical sensors that can generate their own energy from compounds already present in the body to power implantable devices, such as cardiac pacemakers.

“To conduct impactful bioelectronics work, I need to be in an environment where there are biologists, the people who can give me feedback on what I develop,” says Inal.

Bio-inspired computers and animal tracking
Bioelectronics not only encompass electronic devices designed to solve biological problems, they are also electronic solutions inspired by biology.

Khaled Salama is interested in a relatively new type of bio-inspired device called a "memristor"4. These are electrical components inspired by the neural networks and synapses of the brain. Researchers hope they will lead to the next generation of computing systems and that they will be better equipped to very rapidly process huge amounts of data. Salama has developed an approach that improves their computational efficiency while reducing power consumption in these typically energy-intensive devices.

Sensing data in harsh marine environments can be particularly challenging, says Kosel. Researchers have often resorted to electronic tags placed on large marine animals to track their movements. They also use electronic sensors to conduct flow, salinity, pressure and temperature measurements in the sea. Smaller, lighter, less power-hungry tags are needed to resist corrosion, and withstand biofouling, a bacterial crust that forms on almost anything that stays in the sea for too long.

Kosel’s solution was to develop graphene sensors fabricated with a single-step laser-printing technique for marine applications. These laser-induced graphene sensors are resistant to corrosion and can survive high temperatures. They are very light and flexible, making them suitable for attaching to smaller marine animals. They also developed a technique5 that involves conducting high-frequency measurements that allow them to withstand the effects of an accumulating biofouling layer.

The group have started a conference, which will be held annually at KAUST. Last year, among the many esteemed attendees was George Malliaras, a Prince Philip Professor of Technology at the University of Cambridge. Malliaras praised the university for its world-class instrumentation, access to excellent collaborations within the campus and mechanisms to collaborate with people abroad. He says, "Taken together, these attributes have made KAUST very successful at addressing some of the most important problems that humanity faces today." 

Tags:  Bioelectronics  George Malliaras  Graphene  Healthcare  Jasmeen Merzaban  Jurgen Kosel  Khaled Salama  King Abdullah University of Science and Technology  Muhammad Hussain  nanoparticles  Niveen Khashab  Sahika Inal  semiconductor  University of Cambridge 

Share |
PermalinkComments (0)
 
Page 1 of 2
1  |  2