Photon Science Institute
Photon Science Institute
News Article | May 15, 2017
Research from The University of Manchester has thrown new light on the use of miniaturized “heat engines” that could one day help power nanoscale machines like quantum computers. Heat engines are devices that turn thermal energy into a useful form known as “work” which can provide power — like any other engine. Dr. Ahsan Nazir, a Senior Lecturer and EPSRC Fellow based at Manchester’s Photon Science Institute and School of Physics and Astronomy, wanted to see how heat engines performed at the quantum level, a sub-atomic environment where the classical laws of physics don’t always apply. Heat engines at this scale could help power the miniaturized nanoscale machines of the future, such as components of quantum computers. Nazir’s research, published in the journal Physical Review E, showed that heat engines were inclined to lose performance at the quantum scale due to the way such devices exchange energy with external heat reservoirs — and more investigation would be needed to remedy this challenge. “Heat engines are devices that turn thermal energy into a useful form known as ‘work’,” explains Nazir. “Besides being of immense practical importance, the theoretical understanding of factors that determine their energy conversion efficiency has enabled a deep understanding of the classical laws of thermodynamics. “Recently, much interest has focused on quantum realizations of engines in order to determine whether thermodynamic laws apply also to quantum systems. “In most cases, these engines are simplified using the assumption that the interaction between the working system and the thermal reservoirs is vanishingly small. At the classical macroscopic scale this assumption is typically valid — but we recognized this may not be the case as the system size decreases to the quantum scale. “Consensus on how to approach thermodynamics in this so-called strong coupling regime has not yet been reached. So we proposed a formalism suited to the study of a quantum heat engine in the regime of non-vanishing interaction strength and apply it to the case of a four stroke Otto cycle. “This approach permitted us to conduct a complete thermodynamic analysis of the energy exchanges around the cycle for all coupling strengths. We find that the engine’s performance diminishes as the interaction strength becomes more appreciable, and thus non-vanishing system-reservoir interaction strengths constitute an important consideration in the operation of quantum mechanical heat engines.”
News Article | May 15, 2017
Heat engines are devices that turn thermal energy into a useful form known as 'work' which can provide power – like any other engine. Dr Ahsan Nazir, a Senior Lecturer and EPSRC Fellow based at Manchester's Photon Science Institute and School of Physics and Astronomy, wanted to see how heat engines performed at the quantum level, a sub-atomic environment where the classical laws of physics don't always apply. Heat engines at this scale could help power the miniaturised nanoscale machines of the future, such as components of quantum computers. Dr Nazir's research, published in the journal Physical Review E, showed that heat engines were inclined to lose performance at the quantum scale due to the way such devices exchange energy with external heat reservoirs – and more investigation would be needed to remedy this challenge. "Heat engines are devices that turn thermal energy into a useful form known as 'work'," explained Dr Nazir. "Besides being of immense practical importance, the theoretical understanding of factors that determine their energy conversion efficiency has enabled a deep understanding of the classical laws of thermodynamics. "Recently, much interest has focused on quantum realisations of engines in order to determine whether thermodynamic laws apply also to quantum systems. "In most cases, these engines are simplified using the assumption that the interaction between the working system and the thermal reservoirs is vanishingly small. At the classical macroscopic scale this assumption is typically valid – but we recognised this may not be the case as the system size decreases to the quantum scale. "Consensus on how to approach thermodynamics in this so-called strong coupling regime has not yet been reached. So we proposed a formalism suited to the study of a quantum heat engine in the regime of non-vanishing interaction strength and apply it to the case of a four stroke Otto cycle. "This approach permitted us to conduct a complete thermodynamic analysis of the energy exchanges around the cycle for all coupling strengths. We find that the engine's performance diminishes as the interaction strength becomes more appreciable, and thus non-vanishing system-reservoir interaction strengths constitute an important consideration in the operation of quantum mechanical heat engines." Explore further: What is quantum in quantum thermodynamics? More information: David Newman et al. Performance of a quantum heat engine at strong reservoir coupling, Physical Review E (2017). DOI: 10.1103/PhysRevE.95.032139
News Article | May 11, 2017
It's strong, it's flexible, and it's here. After a long time cooking in the labs, the first graphene-based products are beginning to trickle out into the world of smartphones, wearables, batteries, virtual reality, sports equipment, super-capacitors and supercars. It's a material that some believe has been coerced from abandoned space ships, left on Earth by distant races years ago. While that's a little unlikely, the power of this super-thin, strong, conductive and all-round amazing material is deserving of such a conspiracy. It's been over 60 years coming as scientists and manufacturers alike have struggled to harness the power of this awesome material, but it's closing in on revolutionizing so many things we're using day to day. At MWC 2017, FlexEnable showed-off a full color, graphene-based mechanical pixel system for low-power displays and e-ink displays – that’s a paper-thin Kindle-like device to you and me. The big breakthrough for the e-ink screen is using printed graphene instead of brittle titanium oxide. “We try to replace some of the metal conductors with printed graphene to make the devices more flexible,” says Dr. Rouzet Agaiby at FlexEnable, whose plastic electronics still tend to include some (non-flexible) silicon. “A Kindle is only thick because it’s on glass.” It’s all very well having an electric car, but only if it accelerates as quickly as its petrol counterparts. That means they need to be super-light. So how about we replace glass and metal with plastics, carbon fiber... or graphene? Cue a limited-edition supercar starting at £130,000 (around $163,000/AU$215,000) from British manufacturer Briggs Motor Company, whose structural components include graphene, so are lighter and stronger than carbon fiber composite, and therefore much more energy-efficient. Another way of using graphene to increase acceleration is super-capacitors containing graphene for energy recovery; its super-conductive properties create a super-efficient KERS (Kinetic Energy Recovery System). Skeleton Technologies has shown exactly that using curved graphene, which saves on fuel consumption (or reduces electricity use). Printed electronics are the next big thing, and graphene is at the forefront. Costing just a few pennies each are paper wristbands or tickets, which have graphene ink printed onto them. In a recent demo, the proximity of a graphene RFID tag to a reader caused a picture to be taken of the wearer or holder. "This could be used in closed environments such as airports for monitoring passengers boarding a high security flight, or on the London Underground to track which entrances and exits passengers take just by tracking their ticket," says Dr Thanasis Georgiou, VP, Graphene Security Ltd., Photon Science Institute, University of Manchester. "Products in supermarkets could have [graphene-based] RFID technology on them so you could know in real-time where products are." As well as making shop-lifting much harder, and perhaps even getting rid of the checkout altogether, a connected Internet of Things-like system would be able to see instantly when stocks of specific products are running low. How about a totally wearable prosthetic hand like Luke Skywalker wears in The Empire Strikes Back? Graphene inks have been used by the Istituto Italiano di Tecnologia (IIT) to make the Prosthetic IIT-NAIL Hand, which uses graphene ink on paper as the electrodes, replacing titanium. Doing so gets rid not only of titanium and all cables taking biomedical electrical signals from muscles to the hand, but it means the control system can have direct contact with the stump. The Prosthetic IIT-NAIL Hand is flexible, more comfortable and cheaper to make than existing techniques. It conducts, it’s flexible, and it’s safe when used against flesh. Cue a graphene contact lens – officially an ‘electronic retinal prostheses’ – that helps patients that have lost their sight but still have a functional optic nerve. The brainchild of Jose Antonio Garrido, director of the Group of Advanced Electronic Materials and Devices at Institut Català de Nanociència i Nanotecnologia (ICN2), graphene is used to effectively detect and translate more light into electrical signals, increasing the resolution of images perceived by the patient's brain. It’s still under development. What if you could charge your phone in five minutes? That’s the thinking behind the Zap & Go charger, which takes full advantage of graphene’s conductive prowess to fully charge in five minutes, though the prototype is only a 750mAh battery. It's due to launch later in 2017. Meanwhile, the Watt Laboratory (under Huawei's Central Research Institute) also recently used graphene to allow lithium ion batteries to run at temperatures of 60°C, roughly 10°C hotter than standard batteries, thereby prolonging the lifespan of the power pack. It also held a charge for twice as long. Soon, Fitbit, Jawbone, Misfit and other fitness 'wristables' are going to look clunky – and dumb. Graphene promises not only much thinner (even paper-thin) wristbands, but they'll have integrated graphene light sensors and circuitry that bring extra functionality just by using light. Wearables that measure your activity and heart rate are everywhere, but they’re bulky, and their one-trick function is becoming boring. Cue graphene-enabled health patches for patients in hospitals, for sports, and for everyone else. “Wellness sensing in the future will be something like a disposable e-tattoo, which has graphene that senses vital signs like heart rate, oxygen saturation, and skin temperature, breathing rate and even UV light exposure when you’re at the beach,” says Stijn Goossens, Postdoctoral research engineer, Nano-optoelectronics, Institute of Photonic Sciences (ICFO) in Barcelona. “With oxygen saturation alone you can predict if someone is getting the flu,” he says, adding that even the digital circuits are one-atom thin, including a Bluetooth chip. Enabled by a flexible and transparent graphene-based sensing platform, the key advantage is that a power-hungry LCD screen isn’t needed. And that means it can be super-thin. Who needs silicon? Researchers from TU Delft and Spain's Graphenea have found a new way to create mechanical pixels using tiny balloon-like structures. Each pixel is a two-atom thick graphene membrane 13 micrometers wide, and although they don't emit light, they are visible in sunlight so could suit e-books and smartwatches. Oh, and they're full color; thanks to interference between light waves reflected from the bottom of the cavity and the membrane on top, which can be controlled using pressure. The researchers are now working to control the color of the membranes electrically. It’s very easy to get drunk on the possibilities of graphene, and it doesn’t get easier than with the ICN2’s graphene quantum dots printed on paper that can detect certain contaminants. It means the ICN2’s patented sensor, when placed in a phone, exploits the optical properties of graphene quantum dots to detect the presence of pesticides in wine, water, or anything else. “Light comes from the graphene quantum dots, interacts with the compounds, and you see changes in the light’s color,” says Professor Dr. Arben Merkoçi, director of the Nanobioelectronics and Biosensors Group at the ICN2. “All it uses is paper, a smartphone, and graphene.” It could have uses in hospitals, or anywhere you don’t believe the booze. Graphene can also be used to make super-thin, super-sensitive image sensors that can detect invisible infra-red light. Cue spectral applications to differentiate between different organic materials, with a quick photo revealing exactly how ripe fruit is, or whether baby milk is toxin-free; all from a smartphone. “Our prototype is built on graphene and CMOS integration that can sense both visible and infra-red light,” says Goossens at the ICFO. “In the near future we can produce them in very high quantity at very low cost for smartphones.” If you've read up on graphene, you may have heard optimistic reports of a graphene camera that's 1000x more sensitive to light than the ones we have today, conjuring visions of pixel-perfect night shots. While you won't want to get your hopes up for that just yet, a more recent project from the University of Michigan deserves a closer look. It's a DSLR-size camera that uses multiple translucent graphene sensors to create a 3D map of a scene, so that you can pick your focus point after taking a shot. This is a graphene alternative to the 'light field' Lytro Illum, but where the graphene camera uses multiple sensor layers, the Illum needs an array of hundreds of thousands of micro lenses to create its images. "Graphene detectors can offer very high sensitivity, so you don't really sacrifice the clarity by making them transparent," says associate professor of electrical engineering and computer science Zhaohui Zhong. The tech could be slimmed down to fit into a phone. The ability to see in the infrared – effectively night vision – means that same graphene CMOS camera can be used as part of a self-driving car’s automatic brake system, specifically in bad weather. “Now they use visible cameras, but in dense fog they’re useless,” says Goossens of this collision avoidance tech. Autonomous cars will also probably use LIDAR sensors to constantly scan the area around them, but it’s a relatively slow technology. At Mobile World Congress 2017 in Barcelona, the ICFO had a Scalextric-style track with two VW camper vans buzzing around, with the following vehicle stopping in its tracks as soon as the front vehicle braked in a ‘fog box’. Graphene's transparent appearance and super low-power means it can be used in some unexpected places. Since it's got super-low power consumption and it's highly sensitive, the tech could be used in inert materials such as windows. "The light sensors can be embedded in anything, so you could think about putting it in windows or other places where there's no power, such as packaging," says Goossens. "In a window in a building it could detect whether it's night or day for your curtains to open or close automatically." It's also the first step along the way to windows managing to harvest energy during the day and illuminating during the night - while still being transparent. However, a more short-term killer app is probably as a hands-free system in a car. "You would need four sensors to detect a directionality, so in a car window it could detect motion sensing – you could change the track on a CD just by waving your hand," says Goossens. The advantage over existing tech is that graphene can be completely transparent – the entire window could be full of sensors. Drones run out of battery quickly, and their propellers break when they’re landed badly. Cue a drone with 3D-printed graphene composites in its propellers that’s both super-strong and super-light, so more battery-efficient. “Printing with graphene is very easy, but when you start combining it with other polymers and materials, that’s when it gets complicated,” says Charlotte Powell at the University of Manchester’s National Graphene Institute. Nevertheless, the goal of this project with the University of Central Lancashire is to make all parts of the drone with graphene, including more graphene composites in the body and even a graphene-based battery pack and graphene spectral sensors. They’re hard, they’re hot, and they’re heavy, but helmets have already had the graphene treatment. Developed by Italy’s Momodesign and the Istituto Italiano di Tecnologia (IIT), this first-ever graphene-infused carbon fiber helmet capitalizes on the material’s thin, strong and conductive, flexible and light characteristics to create a helmet that absorbs and dissipates impact better than your average helmet. It also disperses heat more efficiently, so it’s cooler. Hardware is dead; the future of phones is flex-ware – and that means graphene making everything curved, bendable and flexible. Oh, and the data super-fast, too. The first Wi-Fi receiver based on graphene, from AMO together with RWTH Aachen University, has 24 Wi-Fi receivers on pieces of plastic and glass, but its makers claim it can work on fabric, paper, glass or plastic, and deal in Bluetooth, 4G and even 5G. Prototypes are working at 2.45Ghz and 5.8Ghz and the creators have circuits that work at up to 90Ghz, which covers the 5G standard. This is printed electronics, which graphene is very much at the forefront of; expect to see RFID tags printed on paper using graphene ink that act as a ticket for concerts and at airports, and even as a method of payment at events and on transport networks. Water, soil and air purification is also possible with graphene. One of these products – Grafysorber from Directa Plus – is super-absorbent, and ideal for oil spills. “One gram of Grafysorber is able to absorb up to 90 grams of oil,” says Laura Rizzi, R&D manager at Directa Plus. The mobile Grafysorber Decontamination Unit contains a plasma machine to produce the wonder material on-site, which is even able to return contaminated water to safe levels for drinking. “Normally you have to use a biological or chemical process to treat contaminated water, but Grafysorber is completely chemical-free,” says Rizzi. It’s also been suggested that the same properties could be used as water membranes that could sieve pure water straight from a contaminated, muddy puddle. It’s not often said, but virtual reality is not very convincing. It needs movement sensors to become so, and what better than a pair of super-responsive gloves that are sensitive to tiny changes in motion and temperature? “Graphene flakes printed in very thin layers are very sensitive to strain,” says Dr Darryl Cotton, Senior Researcher, Nanotechnology, Nokia Research Center in Cambridge. “We’ve also put reduced graphene oxide into a temperature sensor.” The end result is a glove that, for now, sets-off surface-mounted LEDs, but they’re so thin and flexible that they could be used to make virtual reality environments responsive to tiny movements in fingers. Regular audio speakers are very physical things. They use drivers that move back and forwards very quickly, exciting the air to create sound waves. Back in 2013, the University of California at Berkeley made an earphone with a graphene driver, but the material has also been used to create a completely different kind of speaker. A recent article in the ACS Applied Materials & Interfaces journal outlines a thermo-acoustic speaker made using graphene. It's lab-bound right now, but it could be a fit for mobile devices, as it doesn't require the kind of speaker cavity normal dynamic driver speakers need. The way in which it works may sound odd though. A suspension of graphene flakes is freeze-dried to produce an aerogel – an ultra-porous graphene-based structure, a bit like a rigid sponge. This gel is then rapidly heated and cooled to cause air movement similar to that of a normal speaker cone. We're yet to see how much battery drain a thermo-acoustic speaker would cause, and how much discernible heat it might produce – but if it makes a tablet sound more like a mini surround sound system, we're in. In July 2016, Dassi unveiled the first graphene bike frame. As graphene's strength relative to its weight is so high, graphene should make ultra-rigid, extremely light bike frames a cinch to design. The Dassi frame is still predominantly a carbon fiber frame, with some layers of graphene reinforcement at its core, but graphene itself makes up only around one percent of the frame. At this stage it's a proof of concept, particularly as the frame is around the same weight as a top-end all-carbon one, at 750g. However, Dassi claims the weight will eventually be reduced to "500g unpainted". Graphene can also be woven into carbon fiber; Rice University successfully reinforced carbon fiber with graphene flakes in 2013, and a company called Zyvex already makes a carbon fiber graphene composite called Arovex. Vittoria Industries is using graphene in its top of the range Corsa tyres, as well as in its carbon wheels. "We are using graphene-nanoplatelets in the resin, which we impregnate into the carbon fiber," says Giulio Cesareo, CEO of Directa Plus, which supplies the graphene. The end products are lighter, stronger, and more flexible, with extra thermal conductivity in tyres meaning better stiffness and grip.
Cant D.J.H.,Photon Science Institute |
Syres K.L.,Photon Science Institute |
Syres K.L.,University of Nottingham |
Lunt P.J.B.,Photon Science Institute |
And 12 more authors.
Langmuir | Year: 2015
Nanocrystalline thin films of PbS are obtained in a straightforward reaction by precipitation at the interface between toluene (containing a Pb precursor) and water (containing Na2S). Lead thiobiuret [Pb(SON(CNiPr2)2)2] and lead diethyldithiocarbamate [Pb(S2CNEt2)2] precursors are used. The films are characterized by X-ray diffraction and electron microscopy, revealing typical particle sizes of 10-40 nm and preferred (200) orientation. Synchrotron-excited depth-profiling X-ray photoelectron spectroscopy (XPS) is used to determine the depth-dependent chemical composition as a function of surface aging in air for periods of up to 9 months. The as-synthesized films show a 1:1 Pb/S composition. Initial degradation occurs to form lead hydroxide and small quantities of surface-adsorbed -SH species. A lead-deficient Pb1-xS phase is produced as the aging proceeds. Oxidation of the sulfur occurs later to form sulfite and sulfate products that are highly localized at the surface layers of the nanocrystals. These species show logarithmic growth kinetics, demonstrating that the sulfite/sulfate layer acts to passivate the nanocrystals. Our results demonstrate that the initial reaction of the PbS nanocrystals (forming lead hydroxide) is incongruent. The results are discussed in the context of the use of PbS nanocrystals as light-harvesting elements in next-generation solar technology. © 2015 American Chemical Society.
Ahmed N.,Photon Science Institute |
Vaughan J.,Photon Science Institute |
Scully P.,Photon Science Institute |
Stanmore E.,University of Manchester
24th International Conference on Plastic Optical Fibers, POF 2015 - Conference Proceedings | Year: 2015
Improved uptake and adherence to balance and strength exercises has been demonstrated to significantly improve functionality and reduce falls by 40%, helping people to remain independent and maintain their quality of life. Achieving this reduces the burden of illnesses such as osteoarthritis on the healthcare system. We propose a portable, inexpensive balance and lower limb strength rehabilitation device for home use with remote clinical connectivity based on polymer optical fibre (POF) technology. The device will measure balance and adherence to rehabilitation exercise, and ensure that the exercises are carried out correctly and effectively - even in the patient's own home. Measurement of pressure, using POF technology, enables simultaneous and independent monitoring of the ball and heel of each foot forming four quadrants. This economical system displays postural balance and sway analysis as a stabilogram, which combines pressures exerted on all four zones to formulate Centre of Pressure (COP) and Centre of Gravity.
Thomas A.G.,Photon Science Institute |
Jackman M.J.,Photon Science Institute |
Jackman M.J.,University of Manchester |
Wagstaffe M.,Photon Science Institute |
And 6 more authors.
Langmuir | Year: 2014
The adsorption of p-aminobenzoic acid (pABA) on the anatase TiO2(101) surface has been investigated using synchrotron radiation photoelectron spectroscopy, near edge X-ray absorption fine structure (NEXAFS) spectroscopy, and density functional theory (DFT). Photoelectron spectroscopy indicates that the molecule is adsorbed in a bidentate mode through the carboxyl group following deprotonation. NEXAFS spectroscopy and DFT calculations of the adsorption structures indicate the ordering of a monolayer of the amino acid on the surface with the plane of the ring in an almost upright orientation. The adsorption of pABA on nanoparticulate TiO2 leads to a red shift of the optical absorption relative to bare TiO2 nanoparticles. DFT and valence band photoelectron spectroscopy suggest that the shift is attributed to the presence of the highest occupied molecular orbitals in the TiO2 band gap region and the presence of new molecularly derived states near the foot of the TiO2 conduction band. © 2014 American Chemical Society.