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A New, Positive Approach Could Be the Key to Next-Generation, Transparent Electronics
An RMIT University-led team has introduced ultrathin betatellurite to the 2D semiconducting material family, which provides an answer to the decades-long search for a high mobility p-type oxide. Researchers have sought a new class of electronics based on semiconducting oxides, whose optical transparency could enable these fully transparent electronics. These see-through devices could potentially be integrated in glass, flexible displays and in smart contact lenses – bringing to life futuristic devices that seem like the product of science fiction. Dr Torben Daeneke led the collaboration across three FLEET nodes. He said the research was a breakthrough. “This new, high-mobility p-type oxide fills a crucial gap in the materials spectrum to enable fast, transparent circuits.” The oxide-based semiconductors also provide a suite of other benefits, like their stability in the air, less-stringent purity requirements, low costs, and easy deposition. “In our advance, the missing link was finding the right, ‘positive’ approach,” Dr Daeneke said. There are two types of semiconducting materials: ‘n-type’ materials have abundant negatively charged electrons, while ‘p-type’ semiconductors possess positively charged holes. When complementary n-type and p-type materials stack together, it allows for electronic devices to be created, like diodes, rectifiers, and logic circuits. These materials are the building blocks of every computer and smartphone, which are crucial in contemporary living. This project was supported by the Australian Research Council and also by RMIT University’s Microscopy and Microanalysis Facility. It received funding from the McKenzie postdoctoral fellowship program from the University of Melbourne.
The RMIT team from left, Ali Zavabeti, Patjaree Aukarasereenont and Torben Daeneke with transparent electronics.
A molten mixture of tellurium and selenium rolled over a surface deposits an atomically-thin sheet of beta-tellurite. The optical transparency of the new materials could enable futuristic, flexible, transparent electronics. Credit: RMIT University.
Crystal structure of beta-tellurite showing charge density. Above: A magnified image showing nano-thin sheets of the new type of ultra-efficient, flexible and printable piezoelectric material. Credit: RMIT University. Right: The new material could be used to develop devices that convert blood pressure into a power source for pacemakers. Credit: RMIT University.
RMIT researchers have discovered a new type of ultraefficient, nano-thin material that could advance self-powered electronics and even deliver pacemakers powered by heart beats. The flexible and printable piezoelectric material – able to convert mechanical pressure into electrical energy – is 100,000 times thinner than a human hair and 800% more efficient than other piezoelectrics based on similar non-toxic materials. Researchers believe it can be easily fabricated through a costeffective and commercially scalable method through the use of liquid metals. Dr Nasir Mahmood, who led the project, said the material was a major step towards realising the full potential of motiondriven, energy-harvesting devices. “Until now, the best performing nano-thin piezoelectrics have been based on lead, a toxic material that is not suitable for biomedical use.” “Our new material is based on non-toxic zinc oxide, which is also lightweight and compatible with silicon, making it easy to integrate into current electronics,” Dr Mahmood explained. The potential biomedical applications within the materials include internal biosensors and self-powering biotechnologies, including devices that convert blood pressure into a power source for pacemakers. The nano-thin piezoelectrics may also be used in the development of smart oscillation sensors to detect faults in infrastructure like buildings and bridges, especially in earthquake-prone regions. “It’s so efficient that all you need is a single 1.1 nanometre layer of our material to produce all the energy required for a fully self-powering nanodevice,” Dr Mahmood said. The new material is produced using a liquid metal printing approach, which was entirely pioneered at RMIT.
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Researchers Develop Improved Recycling Process for Carbon Fibres
Recycling of composite materials could be up to 70% cheaper and lead to a 90 to 95% reduction in CO2 emissions compared to standard manufacturing. Like other recyclable materials, carbon fibre reinforced polymer (CFRP) composites, non-biodegradable materials have typically lacked a viable recycling method. But researchers from the University of Sydney’s School of Civil Engineering have developed an optimised method for recycling CFRP composites while maintaining 90% of their original strength. “Globally and in Australia there has been a march towards better recycling processes, however there is often the belief that a material can be recycled an infinite number of times – this simply isn’t the case. Most recycling processes diminish mechanical or physical properties of materials,” said Dr Ali Hadigheh, who led the research. CFRP composites are present in many products like wind turbines, plane parts, cars, ships, and technology like laptops and mobile phones. However, they are typically disposed of in landfills or incinerated, which create significant threats to the environment and public health. The research team used an optimised process to support a circular economy. In phase one, ‘pyrolysis’, the material is broken down using heat. The material is significantly charred, which prevents it from developing a good bond with a resin matrix. In the second phase, ‘oxidation’, high temperatures are used to remove the initial char. “Until now, it has been impossible to continuously recycle products made of carbon fibres. Given that most recycling involves shredding, cutting or grinding, fibres are worn out, decreasing a future product’s viability,” Dr Hadigheh said.
The study was led by Dr Pavel Kolesnichenko at Swinburne University of Technology (and now a postdoc at Lund University).
Corresponding author Prof Jeff Davis (Swinburne University of Technology).
‘Target Identified’: Teaching A Machine How to Identify Imperfections In 2d Materials
Just as James Cameron’s Terminator-800 was able to discriminate between clothes, boots, and a motorcycle, machine-learning could soon identify different areas of interest on 2D materials. The simple and automated optical identification of the different physical areas on these materials could significantly accelerate the science of atomically thin materials. Atomically thin layers of matter are a new and emerging class of materials that will serve as the basis for next-generation energyefficient computing, optoelectronics and future smart-phones. Dr Pavel Kolesnichenko led a study into atomically thin materials. “Without any supervision, machine-learning algorithms were able to discriminate between differently perturbed areas on a 2D semiconducting material”. “This can lead to fast, machine-aided characterisation of 2D materials in the future, accelerating application of these materials in next-generation low-energy smart-phones,” he said. Dr Kolesnichenko and Professor Jeffrey Davis from the Swinburne University of Technology discovered that the task of characterising 2D materials could be accomplished by machines in a rapid and automated manner. “In order to understand the impact of different perturbations and minimise or control their presence, it is important to be able to identify them and their spatial distribution rapidly and reliably,” Professor Davis said. The researchers worked with FLEET colleague Professor Michael Fuhrer from Monash University. Together, they applied unsupervised machine-learning algorithms to characterise the semiconducting monolayer of tungsten disulphide. The data was acquired through an apparatus involving a microscope and a spectrometer. The learning algorithms were then able to discriminate between the areas on a monolayer flake affected by doping, strain, disorder, and the presence of additional layers.
BREAKING NEWS
Nanotechnology Offers New Hope for Bowel Cancer Patients
Breakthrough research has found that bowel cancer survival rates could be improved if chemotherapy drugs were delivered through tiny nanoparticles to the diseased organs rather than by oral treatment. A partnership between scientists in India and Australia has studied nanoparticles to target bowel cancer – the third most common cancer in the world and the second deadliest. Experiments have shown that nanoparticles containing the chemotherapy drug, Capecitabine, attach themselves directly to the diseased cells. It then bypasses healthy cells and therefore reduces toxic side effects and the size and number of tumours. The University of South Australia’s Professor of Pharmaceutical Science, Professor Sanjay Garg – the sole Australian researcher involved in the project – said that Capecitabine is the first-line chemotherapy drug for bowel cancer. “Due to its short life, a high dose is necessary to maintain effective concentration, resulting in some harsh side effects when delivered conventionally, including severe hand and foot pain, dermatitis, nausea, vomiting, dizziness and loss of taste,” Professor Garg said. The side effects are exacerbated because the drug affects both healthy and diseased cells. “A viable alternative to conventional therapy is targeted drug delivery using nanoparticles as smart carriers so that the drug can be delivered specifically to the tumour. This allows a smaller and less toxic dose,” Professor Garg explained. When Capecitabine is delivered through nanoparticles, it reduces both the size and number of cancerous bowel tumours, results in fewer abnormal cells, improved red and white blood cell counts and less damage to other organs.
3D illustration of a nanobot attacking a cancer cell. Credit: University of South Australia.
New Tech A Curtain Raiser for Cheap Clean Solar Energy
Recent research from the Australian National University (ANU) shows technology that stores clean energy by heating particles with captured sunlight is cost-effective and reliable. An ANU research team examined solar thermal technology developed by US-partner Sandia National Laboratories. The technology uses concentrated sunlight to heat a ‘curtain’ of falling low-cost particles to 700 degrees Celsius. The heated particles are stored for later use in overnight electricity generation or industrial process heat. They are then lifted up for reheating, providing a highly efficient and cyclical system. “Our modelling shows a concentrated solar power system built around this falling ‘particle curtain’ could generate a megawatt-hour of stored electricity for less than USD $60,” said Associate Professor John Pye. “A least-cost system built at the 100-megawatt scale would come with enough storage to run the turbine for 14 hours, easily enough to allow continuous night-time electricity for large parts of the year,” he explained. The ANU researchers also contributed to the development of a novel multi-stage falling particle solar receiver design, which maximises the amount of light absorbed and retained by the system. It also contributes to the fundamental understanding of how light and particles interact in these systems. In light of this research, the United States Department of Energy recently announced USD $25 million to test the technology at a new facility in New Mexico. Australia will work with the United States on developing the new technology, including trials at the CSIRO solar thermal falling particle test facility.
BREAKING NEWS
Apartment Made from Waste Glass And Textiles Showcases ‘Green’ Ceramics
A new display apartment at at the University of New South Wales (UNSW) shows how recycling techniques could change the way people build homes. An industry-first apartment, which was made using waste materials that have the potential to revolutionise home construction, was recently launched by the UNSW SMaRT Centre and industry partner, Mirvac. The apartment features efficient flooring, wall tiles, kitchen and lighting features, furniture, and artworks, which are made from waste glass and textiles. Mirvac Chief Executive and Managing Director, Susan Lloyd-Hurwitz, said it was time for the property, construction, and design industry to find more sustainable ways to build. “Every year, an estimated 11 billion tonnes of waste are sent to landfill globally. Ninety-two billion tonnes of materials are extracted, with buildings responsible for around 50% of global materials used,” she said. Professor Veena Sahajwalla, who is the Director of the SMaRT Centre, said the furnishings and products were a positive indication of what the future could look like. “These very stylish and functional furnishings and products made in our UNSW SMaRT Centre green ceramics MICROfactorie show what can be done when science, technology and industry vision and commitment come together,” she said. “In Australia, the building industry is responsible for around 60% of the waste we generate. The ‘take, make waste’ approach is no longer acceptable, and we are working hard to find a better, more sustainable way to provide Australians with homes and office buildings that are kinder to the planet,” she concluded.
The kitchen splashback, the front of the island bench and the tubular light fittings on display in the apartment were manufactured using green ceramics. Credit: UNSW.
Mirvac CEO and Managing Director Susan Lloyd-Hurwitz, NSW Energy and Environment the Hon Matt Kean MP and UNSW waste technology pioneer Veena Sahajwalla inspect recycled materials at the launch. Credit: UNSW
DNA-Inspired ‘Supercoiling’ Fibres Could Make Powerful Artificial Muscles for Robots
The double helix structure of DNA is one of the most iconic symbols in science. By imitating the structure of this complex genetic molecule, researchers have found a way to make artificial muscle fibres far more powerful than those found in nature. These may have potential applications in miniature machinery like prosthetic hands and dexterous robotic devices. Many bacteria, like spirochetes, adopt helical shapes. Even the cell walls of plants can contain helically arranged cellulose fibres. Muscle tissues are also composed of helically wrapped proteins that form thin filaments. Many of these naturally occurring helical structures are involved in making things move, like the opening of seed pods and the twisting of trunks, tongues, and tentacles. Helically oriented fibres embedded in a matrix allow complex mechanical actions like bending, twisting, lengthening and shortening, or coiling. This versatility in achieving complex shapeshifting may hint at the reason for the prevalence of helices in nature. Geoff Spinks is a Senior Professor at the University of Wollongong, who has focused his research on double helix structures for several years. “Ten years ago, my work on artificial muscles brought me to think a lot about helices. My colleagues and I discovered a simple way to make powerful rotating artificial muscle fibres by simply twisting synthetic yarns”. “Our latest results show DNA-like supercoiling can be induced by swelling pre-twisted textile fibres. We made composite fibres with two polyester sewing threads, each coated in a hydrogel that swells up when it gets wet and then the pair are twisted together,” he concluded.
