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Graphene detector reveals THz light's polarization

Posted By Terrance Barkan, Saturday, October 10, 2020
Physicists have created a broadband detector of terahertz radiation based on graphene. The device has potential for applications in communication and next-generation information transmission systems, security and medical equipment. The study came out in ACS Nano Letters.

The new detector relies on the interference of plasma waves. Interference as such underlies many technological applications and everyday phenomena. It determines the sound of musical instruments and causes the rainbow colors in soap bubbles, along with many other effects. The interference of electromagnetic waves is harnessed by various spectral devices used to determine the chemical composition, physical and other properties of objects -- including very remote ones, such as stars and galaxies.

Plasma waves in metals and semiconductors have recently attracted much attention from researchers and engineers. Like the more familiar acoustic waves, the ones that occur in plasmas are essentially density waves, too, but they involve charge carriers: electrons and holes. Their local density variation gives rise to an electric field, which nudges other charge carriers as it propagates through the material. This is similar to how the pressure gradient of a sound wave impels the gas or liquid particles in an ever expanding region. However, plasma waves die down rapidly in conventional conductors.

That said, two-dimensional conductors enable plasma waves to propagate across relatively large distances without attenuation. It therefore becomes possible to observe their interference, yielding much information about the electronic properties of the material in question. The plasmonics of 2D materials has emerged as a highly dynamic field of condensed matter physics.

Over the past 10 years, scientists have come a long way detecting THz radiation with graphene-based-devices. Researchers have explored the mechanisms of T-wave interaction with graphene and created prototype detectors, whose characteristics are on par with those of similar devices based on other materials.

However, studies have so far not looked at the details of detector interaction with distinctly polarized T-rays. That said, devices sensitive to the waves' polarization would be of use in many applications. The study reported in this story experimentally demonstrated how detector response depends on the polarization of incident radiation. Its authors also explained why this is the case.

Study co-author Yakov Matyushkin from the MIPT Laboratory of Nanocarbon Materials commented: "The detector consists of a silicon wafer 4 by 4 millimeters across, and a tiny piece of graphene 2 by 5 thousandths of a millimeter in size. The graphene is connected to two flat contact pads made of gold, whose bow tie shape makes the detector sensitive to the polarization and phase of incident radiation. Besides that, the graphene layer also meets another gold contact at the top, with a nonconductive layer of aluminum oxide interlaid between them."

In microelectronics, this structure is known as a field transistor (fig. 1), with the two side contacts usually referred to as a source and a drain. The top contact is called a gate.

Terahertz radiation is a narrow band of the electromagnetic spectrum between microwaves and the far infrared light. From the applications standpoint, an important feature of T-waves is that they pass through living tissue and undergo partial absorption but cause no ionization and therefore do not harm the body. This sets THz radiation apart from X-rays, for example.

Accordingly, the applications traditionally considered for T-rays are medical diagnostics and security screening. THz detectors are also used in astronomy. Another emerging application is data transmission at THz frequencies. This means the new detector could be useful in establishing the 5G and 6G next-generation communication standards.

"Terahertz radiation is directed at an experimental sample, orthogonally to its surface. This generates photovoltage in the sample, which can be picked up by external measurement devices via the detector's gold contacts," commented study co-author Georgy Fedorov, deputy head of the MIPT Laboratory of Nanocarbon Materials. "What's crucial here is what the nature of the detected signal is. It can actually be different, and it varies depending on a host of external and internal parameters: sample geometry, frequency, radiation polarization and power, temperature, etc."

Notably, the new detector relies on the kind of graphene already produced industrially. Graphene comes in two types: The material can either be mechanically exfoliated or synthesized by chemical vapor deposition. The former type has a higher quality, fewer defects and impurities, and holds the record for charge carrier mobility, which is a crucial property for semiconductors. However, it is CVD graphene that the industry can scalably manufacture already today, making it the material of choice for devices with an ambition for mass production.

Another co-author of the study, Maxim Rybin from MIPT and Prokhorov General Physics Institute of the Russian Academy of Sciences is the CEO of graphene manufacturer Rusgraphene, and he had this to say about the technology: "The fact that it was CVD graphene that we observed plasma wave interference in, means such graphene-based THz detectors are fit for industrial production. As far as we know, this is the first observation of plasma wave interference in CVD graphene so far, so our research has expanded the material's potential industrial applications."

The team showed that the nature of the new detector's photoresponse has to do with plasma wave interference in the transistor channel. Wave propagation begins at the two opposite ends of the channel (fig. 2), and the special geometry of the antenna makes the device sensitive to the polarization and phase of the detected radiation. These features mean the detector could prove useful in building communication and information transmission systems that operate at THz and sub-THz frequencies.

The study reported in this story was co-authored by researchers from the MIPT Laboratory of Nanocarbon Materials and their colleagues from Moscow State Pedagogical University, Ioffe Institute of the Russian Academy of Sciences, and the University of Regensburg, Germany. This research was supported by the Russian Foundation for Basic Research and the Russian Ministry of Science and Higher Education.

Tags:  2D materials  chemical vapour deposition  Georgy Fedorov  Graphene  Maxim G Rybin  MIPT Laboratory of Nanocarbon Materials  Moscow State Pedagogical University  Yakov Matyushkin 

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Intelligent nanomaterials for photonics

Posted By Terrance Barkan, Friday, October 9, 2020
At the latest since the Nobel Prize in Physics was awarded for research on graphene in 2010, 2D materials – nanosheets with atomic thickness – have been a hot topic in science.

This significant interest is due to their outstanding properties, which have enormous potential for a wide variety of applications. For instance, combined with optical fibres, 2D materials can enable novel applications in the areas of sensors, non-linear optics, and quantum technologies. However, combining these two components has so far been very laborious. Typically, the atomically thin layers had to be produced separately before being transferred by hand onto the optical fibre. Together with Australian colleagues, Jena researchers have now succeeded for the first time in growing 2D materials directly on optical fibres. This approach significantly facilitates manufacturing of such hybrids. The results of the study were reported recently in the renowned journal on materials science “Advanced Materials”.

Growth through a technologically relevant procedure
“We integrated transition metal dichalcogenides – a 2D material with excellent optical and photonic properties, which, for example, interacts strongly with light – into specially developed glass fibres,” explains Dr Falk Eilenberger of the Univer­sity of Jena and the Fraunhofer Institute for Applied Optics and Precision Engineering (IOF) in Germany. “Unlike in the past, we did not apply the half-nanometre-thick sheet manually, but grew it directly on the fibre,” says Eilenberger, a specialist in the field of nano­photonics. “This improvement means that the 2D material can be integrated into the fibre more easily and on a large scale. We were also able to show that the light in the glass fibre strongly interacts with its coating.” The step to a practical application for the intelligent nanomaterial thus created is no longer very far away.

The success has been achieved thanks to a growth process developed at the Institute of Physical Chemistry of the University of Jena, which overcomes previous hurdles. “By ana­lysing and controlling the growth parameters, we identified the conditions at which the 2D material can directly grow in the fibres,” says Jena 2D materials expert Prof. Andrey Turchanin, explaining the method based on chemical vapour deposition (CVD) techniques. Among other things, a temperature of over 700 degrees Celsius is necessary for the 2D material growth. 

Hybrid material platform
Despite this high temperature, the optical fibres can be used for the direct CVD growth: “The pure quartz glass that serves as the substrate withstands the high temperatures extremely well. It is heat-resistant up to 2,000 degrees Celsius,” says Prof. Markus A. Schmidt of the Leibniz Institute of Photonic Technology, who developed the fibres. “Their small diameter and flexibility enable a variety of applications,” adds Schmidt, who also holds an endowed professorship for fibre optics at the University of Jena.

The combination of 2D material and glass fibre has thus created an intelligent material platform that combines the best of both worlds. “Due to the functionalisation of the glass fibre with the 2D material, the interaction length between light and material has now been significantly increased,” says Dr Antony George, who is developing the manufacturing method for the novel 2D materials together with Turchanin.

Sensors and non-linear light converters
The team envisages potential applications for the newly developed materials system in two particular areas. Firstly, the materials combination is very promising for sensor technology. It could be used, for example, to detect low concentrations of gases. To this end, a green light sent through the fibre picks up information from the environment at the fibre areas functionalised with the 2D material. As external influences change the fluorescent properties of the 2D material, the light changes colour and returns to a measuring device as red light. Since the fibres are very fine, sensors based on this technology might also be suitable for applications in biotechnology or medicine.

Secondly, such a system could also be used as a non-linear light converter. Due to its non-linear properties, the hybrid optical fibre can be employed to convert a monochromatic laser light into white light for spectroscopy applications in biology and chemistry. The Jena researchers also envisage applications in the areas of quantum electronics and quantum commu­nication.

Exceptional interdisciplinary cooperation
The scientists involved in this development emphasise that the success of the project was primarily due to the exceptional interdisciplinary cooperation between various research institutes in Jena. Based on the Thuringian research group “2D-Sens” and the Collaborative Research Centre “Nonlinear Optics down to Atomic Scales” of Friedrich Schiller University, experts from the Institute of Applied Physics and Institute of Physical Chemistry of the University of Jena; the University’s Abbe Center of Photonics; the Fraunhofer Institute for Applied Optics and Precision Engineering IOF; and the Leibniz Institute of Photonic Technology are collaborating on this research, together with colleagues in Australia.

“We have brought diverse expertise to this project and we are delighted with the results achieved,” says Eilenberger. “We are convinced that the technology we have developed will further strengthen the state of Thuringia as an industrial centre with its focus on photonics and optoelectronics,” adds Turchanin. A patent applica­tion for the interdisciplinary team’s invention has recently been filed.

Tags:  2D materials  Andrey Turchanin  chemical vapour deposition  Falk Eilenberger  Fraunhofer Institute for Applied Optics and Precis  Graphene  Leibniz Institute of Photonic Technology  Markus A. Schmidt  nanomaterials  optical fibres  photonics  quantum technologies  Univer­sity of Jena 

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Laser used to transfer graphene for tech applications

Posted By Graphene Council, Monday, September 21, 2020
Laser has been used to cut to shape and deposit graphene on a target substrate in a single step process, potentially lowering device fabrication time and cost. Graphene patches with diameters as small as 30 micrometers were transferred onto technologically relevant substrates.

The preferred method for production of large-area graphene is chemical vapour deposition (CVD), which allows roll-to-roll scalable production of good quality material. CVD is widely used to create graphene films and devices for industrial and research applications. The CVD process is most commonly restricted to growth on catalytic substrates, such as thin copper films.

In order to produce finished devices, such as field effect transistors, graphene needs to be transferred onto a technologically usable substrate, most commonly a silicon or silica wafer. The common methods of transferring graphene involve polymer intermediary overlayers, application of lithographic masking layers and chemical etching, steps that increase process complexity and reduce the quality of the pristine graphene. Laser-induced localized transfer bypasses all these steps, simplifying device fabrication.

Laser-induced transfer utilizes high power femtosecond laser pulses to “peel” graphene off a substrate. A possible explanation for the underlying physical mechanism is thermal expansion of the substrate, in this case nickel metal, which leads to a rupture of the graphene sheet at the edges of the laser-illuminated area. The research team, joining forces from the UK, Greece, Spain and Israel, having published their results in the journal Applied Surface Science, believes that laser transfer has the potential to eliminate many time-consuming lithographic processing steps, allowing precise, direct application of 2D materials with complex shapes to specific locations on a device, although they acknowledge that the process should be further refined to improve on the quality of the transferred material.

Tags:  2D materials  chemical vapour deposition  CVD  Graphene  Graphenea 

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Combining graphene and nitrides for high-power, high-frequency electronics

Posted By Graphene Council, Thursday, August 20, 2020
Researchers at Graphene Flagship partners CNR-IMM, Italy, CNRS-CRHEA, France, and STMicroelectronics, Poland, in collaboration with Graphene Flagship Associate Member TopGaN, Poland, collaborated on the Partnering Project GraNitE to produce graphene-enabled hot electron transistor (HET) devices. Thanks to nitride semiconductors, they achieved devices with current densities a million times higher than previous prototypes.

Nitride semiconductors are in the spotlight for their potential to be incorporated into HETs to improve their properties and performance. HETs are a type of vertical transistor that can operate at frequencies in the terahertz (THz) range, making them very valuable for applications in communications, medical diagnostics and security. Graphene is promising for applications in HETs, owing to its thinness and high conductivity. They are typically made from nitrides of gallium, aluminium or indium, or alloys of these metals. Aluminium and gallium nitrides are key ingredients in high-electron mobility transistors (HEMTs) – one of the technological foundations of 5G communications.

Gallium-based technologies do have their limitations, however, and GraNitE seeks to take advantage of graphene and layered materials to overcome them. The GraNitE team incorporated graphene as an active ingredient into high-powered aluminium-gallium nitride (AlGaN) and gallium nitride (GaN) based nitride transistors to better dissipate heat, by taking advantage of graphene's high thermal conductivity. The devices also operate at higher frequency thanks to the incorporation of high-quality graphene.

The team devised two approaches. Their first was to deposit graphene onto the surface of the nitride semiconductor using chemical vapour deposition (CVD). This resulted in highly homogeneous, nanocrystalline graphene films,1 ­­which could lead to uptake by industry. The second was to grow monolayer graphene using CVD on a copper surface, then to transfer and integrate it into thin layers of AlGaN and GaN. This method resulted in a graphene/AlGaN junction with excellent rectifying properties, ideal for applications in switches, with an injection mechanism tuneable by modifying the AlGaN composition and thickness.2

Graphene Flagship partnering project GraNitE used their graphene nitride junction as a key building block to fabricate prototype HET devices. Their devices had a low voltage threshold and an electric current density six orders of magnitude higher than those in previous silicon tests,2 representing an important advance in the development of hybrid graphene/nitride semiconductors, and paving the way for future exploitation of this technology.

"The integration of graphene and nitride semiconductors is one of the most viable approaches to harness the unique properties of these materials for industrial applications," says Filippo Giannazzo, GraNitE Project Leader and Senior Scientist at Graphene Flagship partner CNR-IMM, Italy.

Tags:  chemical vapour deposition  CNR-IMM  Filippo Giannazzo  Graphene  Graphene Flagship  semiconductors  transistor 

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Graphene on TEM grids for quality and integration studies

Posted By Graphene Council, Wednesday, July 29, 2020
Graphene suspended over grids for transmission electron microscopy (TEM) can have numerous interesting applications in studies of material properties for technological applications. Two recent publications from TU Wien demonstrate the use of graphene on TEM grids for studies of material quality and integration with indium oxide, another technologically relevant material.

The quality of growth of other materials on graphene is of fundamental importance for device applications. The crystallinity and orientation of indium oxide grown on graphene affects the quality of displays and sensors produced from such a heterostructure. In a study published in Advanced Functional Materials, researchers have shown that arrangement of indium oxide crystals on graphene depends on the pressure on which the crystals form. That can have a major impact on the application properties of the combined materials.

Crucial to the success of this study was the availability of free-standing graphene, on which indium oxide is grown. Having graphene which is suspended in vacuum provides a clean picture of the crystal structure, without any background from a substrate. This is achieved by using commercially available graphene suspended over a metallized mesh – a TEM grid. Transmission electron microscopy across such graphene has the best possible resolution, down to the atomic level.

In a second study, the team of scientists showed that graphene on TEM grids can be used to gauge the quality of the graphene itself. Although grown at a high quality on metal substrates with chemical vapour deposition, transfer of graphene to any useful substrate or a TEM grid requires first coating it with a transfer polymer. Numerous polymer removal processes are used at the industrial scale today, nevertheless it has been shown that some residue persists regardless of the cleaning process. The amount of residue directly impacts graphene film performance.

The study, published in the Journal of Chemical Physics, reveals that ion beam spectroscopy can be used as a tool to map with high resolution the local cleanliness of graphene. The results indicate that although some residue always remains, it clusters in small areas, leaving large clean areas that can be used for devices.

These novel studies highlight the usefulness of graphene on TEM grids as a tool in material science and technology research.

Tags:  chemical vapour deposition  Graphene  TU Wien 

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Graphene-coated fibres as low-power wearable body temperature sensors

Posted By Graphene Council, Friday, July 3, 2020
A team of scientists from the UK and Portugal has produced graphene-coated polypropylene (PP) fibres that can be used in wearable textiles as temperature sensors. Operating in the range of 30 to 45 oC at voltages as low as 1 V, textiles incorporating these fibres could be used to actively measure body temperature of the wearer.

Fibres with integrated sensing functionality overcome some key issues related to the use of monolithic sensors that are attached to either clothes or skin, such as ease of use and wearer comfort. Moreover, many attachable sensors are not robust against washing, and some require external high-power voltage supplies. The new graphene-PP based solution resolves all these issues, as described in the application-driven work published in ACS Applied Materials & Interfaces.

PP is a textile fibre material that is strong and transparent, lightweight, eco-friendly and recyclable. The researchers coat PP, an electrical insulator, with graphene to create fibres that are electrically conductive, their resistance changing with temperature. With an outlook for practical device development, the researchers tested two types of graphene that is suitable for mass production, CVD grown and shear exfoliated. The CVD grown graphene exhibited higher sensitivity to temperature, due to its better uniformity. The resistance changes by several percent across temperatures of interest, which is suitable for practical use.

Figure: Graphene on polypropylene fibre temperature sensor – real life use test. Reprinted with permission from ACS Appl. Mater. Interfaces 2020, 12, 26, 29861–29867. Copyright 2020 American Chemical Society.

In order to simulate real-life usage, the novel fibres were tested against bending for up to 1000 cycles and washing in laundry detergent at different temperatures. The devices exhibited excellent stability under all tested conditions. These sensors have potential applications in continuous measurement of human body temperature through integration in garments, or ambient temperature through integration in upholstery.

Tags:  Chemical Vapour Deposition  Graphene  Sensors 

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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 

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Rolls-Royce chooses to partner with GEIC and 2-DTech

Posted By Graphene Council, Thursday, April 23, 2020
Versarien plc is pleased to announce that, following an open innovation call, multinational engineering company Rolls-Royce has selected to work with The University of Manchester's Graphene Engineering Innovation Centre and its Tier 1 partner, Versarien subsidiary, 2-DTech Limited.

The initial programme of work will use the state-of-the-art chemical vapour deposition (CVD) equipment located within the GEIC. The collaboration will look to explore, understand and create technological advances surrounding the use of graphene and other 2D materials used in wiring for next-generation aerospace engine systems.

The work conducted will seek to use the unique properties of these 2D materials to reduce the weight of electrical components, improve electrical performance and also increase resistance to corrosion of components in future engine systems.

The programme aims to present potential economic benefits, through the possibility of significant cost reductions, and global environmental benefits, through the reduction of energy use and lower emissions from electrification.

Neill Ricketts , Chief Executive of Versarien commented:
"The pursuit of sustainability has become an important goal for many companies in recent years. Rolls-Royce is one of the world's leading industrial technology companies and today, the size and impact of the markets its serves makes this task more urgent than ever. Taking advantage of advanced materials such as graphene, has the potential to revolutionise these markets and add real benefit.

" The partnership with Rolls-Royce is a significant endorsement to 2-DTech's work over the years and we are delighted it has been chosen by such a renowned business and look forward to working together."  

Dr Al Lambourne , Materials Specialist at Rolls - Royce, commented:
" Partnering with the GEIC and its members makes perfect sense to Rolls-Royce as we explore the opportunities and properties of a new class of 2D materials. Using the unique capabilities of 2-DTech and the GEIC we hope to address some of the challenges facing materials in the global aerospace industry , as we pioneer the electrification of future aircraft . "

James Baker, Graphene@Manchester CEO, commented:
"The GEIC is intended to act as an accelerator for graphene commercialisation, market penetration and in the creation of the material supply chain of graphene and 2D materials. It's great to see a company like Rolls-Royce partner with us and our other Tier 1 member, 2-DTech, to capitalise on our world-leading expertise and experience, along with specialist equipment, which will accelerate the product and process development and market entry."

Tags:  2D materials  2-DTech  Aerospace  Al Lambourne  chemical vapour deposition  corrosion  Graphene  Graphene Engineering Innovation Centre  James Baker  Neill Ricketts  Rolls-Royce  University of Manchester  Versarien 

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Graphene Wearables: Exploring Next-Gen Electronics

Posted By Graphene Council, Wednesday, April 22, 2020
Wearable technology refers to any class of electronic items that can be comfortably worn on the body. This covers an ever-growing range of application and product segments, from health and fitness trackers to immersive infotainment systems. They are governed by many of the same principles and trends as other electronics markets, namely extremely high consumer demand for greater functionality in smaller formats. Developers are consistently tasked with miniaturizing devices without compromising on battery life or performance, which mandates next-generation material solutions like graphene sensors.

Graphene Wearable Electronics

The wearable electronics market continues to experience enormous commercial growth due to the release of coveted commercial goods like smartwatches and virtual reality (VR) headsets, contributing to an estimated compound annual growth rate (CAGR) of 15.5%. Provided the market continues to grow as expected, the global wearable electronics market will be worth over $67 billion by 2024.

Although commercialized wearable electronics are now well-cemented in the consciousness of global consumers, they occupy a novel segment of the market. Medical and military-grade wearables have been used routinely for years, while professional sports have exploited health and wellness trackers integrated into clothing for almost as long. Graphene wearable electronics are expected to bridge the gap between these more sophisticated market segments and consumers, allowing the general public to benefit from advanced functionality wearables in increasingly ergonomic formats.
Graphene Wearables: UV-Detection Patch

One interesting graphene wearable prototype is a flexible, transparent substrate that can be directly applied to the wearer’s skin. The patch detects and monitors exposure to ultraviolet (UV) rays and, with advanced internet of things (IoT) connectivity, and can alert the user once they have reached a pre-defined threshold of exposure to sunlight. This could help prevent a range of harmful conditions, from sunburn to melanoma.

Graphene-Based Health & Wellness Sensors

Using the same key technology as the previous application, researchers are increasingly hopeful of integrating graphene-based sensors and substrates into fitness trackers with unprecedented levels of functionality. Currently, commercial devices such as smartwatches often feature rudimentary heart-rate monitors based on infrared (IR) sensors, and movement trackers based on integrated accelerometers.

With superior biocompatibility, graphene sensors could offer more detailed insights into a wide range of health and wellness signals, including hydration, oxygen saturation, continuous blood pressure monitoring and temperature.  Additionally, graphene sensors are being developed for pregnant mothers in the form of a wearable patch, that can monitor and track fetal movements in real time, sending potential indicaitons of a problem to medical professionals.

Graphene Sensor Materials from Grolltex

Grolltex is one of the industry-leading producers of single-layer graphene for sensor applications. We utilise a proprietary chemical vapour deposition (CVD) methodology to produce monolayer materials on substrates of your choosing. We are increasingly servicing researchers and product developers with graphene solutions for sensor and wearable applications and are eager to see how the market progresses in the coming years.

Tags:  chemical vapour deposition  Graphene  Grolltex  nanoelectronics  Sensors 

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Graphene and the Coronavirus

Posted By Graphene Council, Friday, March 20, 2020

These are scary times, aren't they? First and foremost, my thoughts and prayers go out to anyone who is directly affected by the current global crisis caused by the SARS-CoV-2 coronavirus. It's an extremely serious issue that will require worldwide cooperation to overcome.

I have very clear and distinct memories of the previous SARS epidemic. In March 2003, while working at Rice University, I was helping to lead a group of ~50 science and engineering students on an overseas study trip to Hong Kong and Singapore with my former Rice colleague, Dr. Cheryl Matherly (who is now at Lehigh University). We were caught in the middle of the rapidly developing crisis and our travel itinerary had us departing Singapore for Hong Kong on the day the Singapore government warned its own citizens not to travel to Hong Kong!

Fortunately, everyone in our student group made it through that experience safely, and as unsettling as it was, the current situation is much much worse, with as yet unknown - but sure to be significant - social, economic and political ramifications that will most definitely impact future generations around the world.

I am currently based in Bangkok, Thailand, which is a global tourist destination. While we were fortunately to escape the first wave of of the SARS-CoV-2 virus that emanated from China, we're now faced with a second wave imported from Europe. We're not quite under total lockdown here, but things appear to be headed in that direction. It is clear to me form observation that the several governments in the region (Singapore, Hong Kong, and Taiwan, to be specific) are applying the lessons they learned from the previous SARS epidemic to help control the current pandemic. This give me hope, and the circumstances in general have given me plenty of time to think and reflect about what - if anything - I and my company, planarTECH, can do to improve this situation.

Graphene: The "Wonder Material"

I was lucky to fall into the world of graphene and 2D materials by accident through acquaintance with another former Rice University colleague, Dr. James Tour, and conversations I had with him 8 years ago. I will not spend a lot of time here talking about the specific properties of graphene as such information is widely available. The European Union's Graphene Flagship project, for example, has an excellent overview. The University of Manchester - where graphene was first isolated and where planarTECH's Chairman, Ray Gibbs, currently serves as the Director of Commercialization for the Graphene Engineering and Innovation Centre - also has a fantastic YouTube channel with many instructive videos about graphene and its properties.

With all of the amazing properties of graphene, the question is, can it offer any kind of solution to the current pandemic and global crisis?

Academic Work: Graphene's Antiviral Properties

The short answer to the question above is "possibly," but with some caveats. In particular, it would appear that graphene oxide (GO) may play a role in providing a solution.

I should say that I am not a doctor, an epidemiologist or someone with formal training in the biological sciences. I am an engineer by trade, and for the last 8 years, an entrepreneur in the field of graphene. However, since entering the graphene industry, I have grown accustomed to reading academic papers in order to understand the potential applications for graphene.

A paper published in 2015 by researchers at the Huazhong Agricultural University (ironically located in Wuhan, China, where the current pandemic originated) explored the antiviral properties of graphene oxide, and the authors of the paper concluded "that GO and rGO exhibit broad-spectrum antiviral activity toward both DNA virus (PRV) and RNA virus (PEDV) at a noncytotoxic concentration," and that "the broad-spectrum antiviral activity of GO and rGO may shed some light on novel virucide development." While encouraging, it should be noted that the researchers looked specifically at pseudorabies virus (PRV) and porcine epidemic diarrhea virus (PEDV), not the SARS-CoV-2 virus responsible for the current global pandemic.

Another paper published in 2017 by researchers at Southwest University in China looked at cyclodextrin functionalized graphene oxide and it's possible role in combatting respiratory syncytial virus (RSV), concluding that "the curcumin loaded functional GO was confirmed with highly efficient inhibition for RSV infection and great biocompatibility to the host cells." Likewise, a third paper published in 2019 by researchers at Sichuan Agricultural University in China demonstrated that "GO/HY [graphene oxide/hypericin] has antiviral activity against NDRV [novel duck reovirus] both in vitro and in vivo."

The conclusion we can draw from these works is that graphene oxide may offer a platform to fight a variety of viral infections (such as the SARS-CoV-2 coronavirus), possibly as some form of coating, though certainly more work needs to be done.

(Note that my good friends over at The Graphene Council had a recent and excellent blog post covering the same 3 articles in a little more detail. And kudos to them for shining light on the topic before me!)
Productization: From Lab to Market

If there's one thing I've learned from the past 8 years being involved with graphene commercialization (and the past 14 years working directly in the Asian supply chain) is that it is one matter to write an excellent academic paper as a proof-of-concept, but it is an entirely different matter to take work from an academic lab and turn it into a real product.

With respect to graphene in general, what we are seeing today is definite movement on the Gartner hype cycle from the Trough of Disillusionment to the Slope of Enlightenment. Real products using graphene are now on the market. One such example is the recent announcement of of a collaboration between UK-based Haydale Graphene Industries plc and Korea-based ICRAFT Co., Ltd. that results in the release of a graphene cosmetic face mask. And I am pleased to be able to say that - in connection with my previous responsibilities for Haydale's Asia-Pacific operations - I had some role (together with my colleague Yong-jae "James" Ji) in getting this product off the ground and into the marketplace.

While this may seem like a trivial accomplishment given the context and seriousness of the current global pandemic, I offer this example as proof that graphene can be utilized in an everyday, cost-sensitive product, and it is not such a great conceptual leap to go from a cosmetic face mask to a protective face mask, which as we all know are in great demand these days (especially here in Asia). I would invite iCRAFT (or anyone else) to consider collaboration with planarTECH to develop such a product. (Above photo courtesy of Macau Photo Agency on Unsplash.)

Productization: Existing Products?

Very much related to this topic and very curious is a recent public announcement by LIGC Applications of its Guardian G-Volt face mask with a graphene-based filtration system. However, my understanding is that LIGC is not employing graphene specifically for it's potential antiviral properties but rather for its potential to enhance a filtration system, including (due to graphene's electrical conductivity) the ability to pass an electrical charge through the mask that "would repel any particles trapped in the graphene mask."

What I find very curious about this case is that subsequent to this announcement, LIGC's Indiegogo crowdfunding campaign, which was live, has now been placed under review, and the company's pitch video on YouTube has likewise been made private. I do not know what has happened here - perhaps is was perceived as poor timing? - but as a fellow entrepreneur who is conducting my own crowdfunding campaign, I wish LIGC the best of luck with its product development and ultimate launch. I definitely want to see more viable graphene products in the marketplace.

The Graphene Supply Chain: planarTECH's Role

One of the challenges the graphene industry faces overall is scalability. Very few graphene companies today (if any at all) can produce graphene at the scale, at the right cost, and with the consistent quality such that it can be used for truly high-volume applications. Over the past 8 years, I have met numerous customers, mostly in Asia, who want to use graphene in their products but cannot find a secure and stable supply that meets their expectations on specification, volume, and price.

At planarTECH we're interested in not only the end applications, but also in solving this problem of production scalability. While we have in the past mainly been focused on production systems for graphene and other 2D materials by Chemical Vapor Deposition (CVD), we also recently started offering continuous flow production systems for graphene oxide, which we believe can take graphene oxide production from lab-scale, high-cost (grams per week) to production-scale, low-cost (kilograms per hour). We're actively seeking partners to work with us on setting up production and exploration of the application space for graphene oxide, and we're currently conducting a crowdfunding campaign on Seedrs to help us expand our business and make graphene a commercial reality. As seen above, we think graphene oxide's antiviral properties can be exploited to make new and useful products.

I should clarify and caution that planarTECH is not in the position today to offer a graphene-based product that can immediately help alleviate current crisis and prevent widespread infection. Unfortunately, such a product is realistically 1-2 years away. But what we can offer is market expertise specific to graphene, production technologies, and experience in taking products from the idea phase to a reality in the marketplace.

Conclusion: Graphene is a Possible Solution

To conclude, I would like to reiterate a few broad points.

• Graphene (graphene oxide in particular) and coatings made from graphene would appear to have antiviral properties as reported in several published academic papers.
• Real commercial products exist that use graphene, but the industry as a whole still faces challenges around scalability, cost and quality.
• An immediate graphene-based solution to alleviate the effects of the global SARS-CoV-2 coronavirus pandemic is likely unrealistic, but could be possible in the future.
• planarTECH has a role in the supply chain and is seeking partners, as well as investors via its crowdfunding campaign, to expand its business and help end customers develop useful products.

Tags:  2D materilas  chemical vapour deposition  Cheryl Matherly  Graphene  Graphene Engineering and Innovation Centre  Graphene Flagship  graphene oxide  Healthcare  J. Patrick Frantz  James Tour  Lehigh University  planarTECH  Ray Gibbs  Rice University  Yong jae Ji 

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