Cercetătorii descoperă un material excepțional de catod din baterii de metal de magneziu(Researchers discover an exceptional metal-oxide magnesium battery cathode material)

a descoperit un material catodic de metal de magneziu excepțional de metal de metale, cercetătorii mutând un pas mai aproape de livrarea bateriilor care promite o densitate mai mare de stocare a energiei, avansuri în ceea ce privește siguranța, costul și performanța în comparație cu omologii lor ubiquitous litiu-ion (Li-ion). bateriile ar fi mai puțin costisitoare, mai ușoare și mai sigure pentru a permite adoptarea mai ușoară a formatelor de dimensiuni mari necesare vehiculelor electrice și pentru a stoca energia generată de soarele și sursele eoliene.

Posted: Feb 06, 2018

Researchers discover an exceptional metal-oxide magnesium battery cathode material

(Nanowerk News) A multi-institution team of scientists led by Texas A&M University chemist Sarbajit Banerjee has discovered an exceptional metal-oxide magnesium battery cathode material, moving researchers one step closer to delivering batteries that promise higher density of energy storage on top of transformative advances in safety, cost and performance in comparison to their ubiquitous lithium-ion (Li-ion) counterparts.
„The worldwide push to advance renewable energy is limited by the availability of energy storage vectors,” says Banerjee in the team’s paper, published in the journal Chem („Reversible Mg-Ion Insertion in a Metastable One-Dimensional Polymorph of V2O5„). „Currently, lithium-ion technology dominates; however, the safety and long-term supply of lithium remain serious concerns. By contrast, magnesium is much more abundant than lithium, has a higher melting point, forms smooth surfaces when recharging, and has the potential to deliver more than a five-fold increase in energy density if an appropriate cathode can be identified.”
Venadium Pentaoxide
A redesigned metastable phase of vanadium pentoxide (V2O5) shows extraordinary performance as a cathode material for magnesium batteries. The graphic compares the conventional (right) and metastable structures of V2O5. (Image: Justin Andrews, Texas A&M University)
Ironically, the team’s futuristic solution hinges on a redesigned form of an old Li-ion cathode material, vanadium pentoxide, which they proved is capable of reversibly inserting magnesium ions.
„We’ve essentially reconfigured the atoms to provide a different pathway for magnesium ions to travel along, thereby obtaining a viable cathode material in which they can readily be inserted and extracted during discharging and charging of the battery,” Banerjee says.
This rare phenomenon is achieved by limiting the location of the magnesium ions to relatively uncomfortable atomic positions by design, based on the way the vanadium pentoxide is made – a property known as metastability. This metastability helps prevent the magnesium ions from getting trapped within the material and promotes complete harvesting of their charge-storing capacity with negligible degradation of the material after many charge-recharge cycles.

The Ins and Outs of Intercalation
Banerjee, a Davidson Professor of Science in the Texas A&M Department of Chemistry and an affiliated faculty member in the Department of Materials Science and Engineering, has been working for a number of years to better understand ion intercalation – the critical process by which ions like lithium and magnesium move in and out of other materials within intercalation batteries.
Using one of the world’s most powerful soft X-ray microscopes – the Scanning Transmission X-ray Microscope (STXM) and X-ray Emission beamlines – at the Canadian Light Source in tandem with one of the world’s highest resolution aberration-corrected transmission electron microscopes housed at the University of Illinois at Chicago (UIC), Banerjee and collaborators from the Lawrence Berkeley National Laboratory, the UIC and Argonne National Laboratory were able to observe the unique electronic properties of their novel vanadium pentoxide and directly prove magnesium-ion intercalation into the material. Collectively, the team applied decades of combined experience in materials science to explain the fundamental reasons why this new type of vanadium pentoxide is superior to the old version as well as to Li-ion batteries.
Laptops and cell phones are two examples of the many technologies enabled by the rapid development of the lithium-ion battery, which revolutionized energy storage capacity and rechargeability in comparison to its lead-acid and nickel-metal hydride predecessors. However, given the widespread use of lithium not only in portable electronic devices but increasingly in the much larger batteries required for electric vehicles and grid energy storage, lithium is expected to be in increasingly short supply in the long-term. Furthermore, Li-ion batteries are a risky game, as highlighted by recent widely publicized reports detailed in Scientific American, Reuters and Forbes, for example, in which Li-ion-powered devices have either caught fire or exploded as a result of the fundamental flammability and reactivity of lithium.
„Apart from being much safer for consumer applications, magnesium-ion technology is appealing fundamentally because each magnesium ion gives up two electrons per ion – twice the charge, whereas each lithium ion gives up only one,” says Texas A&M chemistry graduate student and NASA Space Technology Research Fellow Justin Andrews, first author on the team’s paper. „This means that, all other considerations aside, if you can store as much magnesium in a material as you can store lithium, you immediately almost double the capacity of the battery.”

Double the Capacity, Double the Trouble
But for all their perceived advantages, magnesium batteries have proven too good to be true since they were first proposed in the 1990s and essentially sidelined by a variety of problems; primarily, the lack of a suitable cathode, or positive electrode – otherwise known as the part of a battery where the magnesium ions enter during discharge of the battery to power an electronic device and then exit during charging.
„Indeed, the most exciting thing about magnesium ions – namely, that they store twice the charge in battery applications – also forms the basis for the biggest challenge,” says collaborating UIC chemist Jordi Cabana. „The higher charge of the magnesium ions make them ‘stick’ much more strongly with surrounding atoms.”
In other words, Banerjee says, the magnesium ions get waylaid as they are traversing through the paths within the cathode material. Their sluggish movement is what makes it so difficult to make viable magnesium batteries.
„In many structures, some of these interactions are very favorable, meaning that the magnesium is quite happy to sit and stay a while in those specific sites,” Andrews explains. „In our material, the magnesium is ‘frustrated’ as it moves through the lattice, because it encounters many less-than-optimal environments. In this sense, it is more than happy to just keep moving right along, leading to an improvement in capacity and diffusion.”
The team’s National Science Foundation-funded research features two additional current and former Texas A&M graduate students, Abhishek Parija and Peter M. Marley, respectively. David Prendergast, a Facility Director at Berkeley Lab’s Molecular Foundry, a U.S. Department of Energy National User Facility for Nanoscale Science Research, helped the Texas A&M team design and interpret their calculations, which were experimentally verified in part by Fakra using Berkeley Lab’s Advanced Light Source along with structural data collected at Argonne National Lab’s Advanced Photon Source. Atomic resolution images of the new form of vanadium pentoxide were collected in collaboration with UIC physicist Robert F. Klie and physics graduate student Arijita Mukherjee and show direct evidence of magnesium intercalated within the material. Battery measurements that show reversibility and confirm the robustness of the cathode material complete the story and were conducted in collaboration with Cabana and former Cabana group member Hyun Deog Yoo.
„On paper, magnesium batteries are highly desirable because they promise greater energy density on top of the ability to solve several of the key issues researchers – and unfortunately consumers – are discovering with lithium-ion batteries, including cost, safety, and performance at the most fundamental levels,” Andrews says. „But the shift from lithium- to magnesium-ion technologies is not straightforward, and the many problems encountered when designing magnesium-ion cathodes have stymied the development of these more sustainable and safer batteries.”

Working Toward a Safer Energy Future
Andrews says the team’s research marks an important turning point in the field because it represents a significant advance toward solving the cathode problem while also highlighting the inherent advantages of using much more imaginative, metastable materials like this new form of vanadium pentoxide. But even he admits there’s much more work to do before this particular ’90s trend comes back in vogue.
„While this research has provided a great deal of insight, there are still several other fundamental problems to overcome before magnesium batteries become a reality,” Andrews adds. „Nevertheless, this work moves magnesium batteries one step closer to reality – namely, a reality where batteries would be less-expensive, lighter and safer for allowing for easier adoption to large-area formats necessary for electric vehicles and to store energy generated by solar and wind sources.”
Source: Texas A&M University

Ceramica de vindecare cu auto-spargere, inspirată de oase, capabilă de recuperare rapidă(Bone-inspired self-crack-healing ceramics capable of quick full strength recovery)

Ceramica auto-vindecată a fost descoperită de un grup de cercetare YNU în 1995. Ușoare și rezistente la căldură, au atras atenția globală pentru utilizarea lor potențială ca materiale de turbină în motoarele de avioane. grupul de cercetare intenționează să dezvolte produse ceramice inovatoare, rezistente la căldură, care nu se vor rupe nici măcar atunci când sunt crăpate prin selectarea unor faze eficiente de vindecare a vindecătorului și, prin urmare, manipularea precisă a capacității de auto-vindecare a ceramici

Posted: Feb 05, 2018

Bone-inspired self-crack-healing ceramics capable of quick full strength recovery

(Nanowerk News) A NIMS-YNU research group discovered that self-healing ceramics undergo three healing stages analogous to bone healing processes: inflammation, repair and remodeling. Using clues provided by bone healing mechanisms, the group added a healing activator to crystalline grain boundaries, enabling the ceramic to fully heal cracks in as little as one minute at 1,000°C, the operating temperature of an aircraft engine (Scientific Reports, „A Novel Design Approach for Self-Crack-Healing Structural Ceramics with 3D Networks of Healing Activator”).
Self-healing process in ceramics
(Left and middle) Self-healing process in ceramics, which completes in as little as one minute. (Right) A network of manganese oxide (green) facilitates self-healing (Image: NIMS)
Self-healing ceramics were discovered by an YNU research group in 1995. Lightweight and heat-resistant, they have been drawing global attention for their potential use as turbine materials in aircraft engines.
However, their self-healing mechanisms had been poorly understood, and cracks only fully healed within a limited temperature range between 1,200 and 1,300°C. Therefore, identification of the mechanism and development of ceramics capable of rapid self-healing within a larger temperature range have long been sought.
The present research group found that self-healing processes occur in three stages: when a ceramic cracks, oxygen enters though the crack and reacts with silicon carbide—a ceramic component—to form silicon dioxide (the inflammation stage). Alumina—a base ceramic material—and silicon dioxide then react to form a gap filling material, sealing the crack (the repair stage).
Finally, the filler crystallizes to restore the original strength in the cracked part (the remodeling stage). In addition, based on the insight that the bodily fluid network in humans promotes the healing of damaged bones, the research group added a trace amount of a healing activator – manganese oxide – to alumina grain boundaries as a 3D network structure.
As a result, newly developed ceramics healed cracks in as little as approximately one minute at 1,000°C, compared to conventional ceramics, which heal cracks in 1,000 hours at 1,000°C.
Based on these results, the research group plans to develop innovative, heat-resistant ceramics which will never break even when cracked by selecting effective healing activator phases and thereby precisely manipulating the self-healing capability of ceramics.
This project was carried out by a research team led by Senior Researcher Toshio Osada (Research Center for Structural Materials (RCSM), NIMS), Group Leader Toru Hara (RCSM, NIMS), Principal Researcher Taichi Abe (RCSM, NIMS), Takahito Ohmura (Deputy Director of the RCSM, NIMS), Chief Researcher Masanori Mitome (International Center for Materials Nanoarchitectonics, NIMS) and Professor Wataru Nakao (Faculty of Engineering, YNU).
Source: National Institute for Materials Science

Respirătoare, electronice portabile pe piele pentru monitorizarea sănătății pe termen lung(Breathable, wearable electronics on skin for long-term health monitoring)

Un senzor electronic hipoalergenic poate fi purtat pe piele continuu timp de o saptamana fara disconfort si este atat de usor si de subtire incat utilizatorii uita ca au chiar si ei, spune un grup de cercetatori de la Universitatea din Tokyo si colaboratorii lor. Electrodul elastic, construit din ochiuri de dimensiuni reduse la nivel de nanoparticule, promite dezvoltarea unor dispozitive neinvazive de e-skin, care pot monitoriza continuu starea de sănătate a unei persoane pe o perioadă lungă de timp ( Nature Nanotechnology , „Inflammation free, permeable gas, lightweight, stretchable on-skin electronics cu nanomeshes ” )

Posted: Feb 05, 2018

Breathable, wearable electronics on skin for long-term health monitoring

(Nanowerk News) A hypoallergenic electronic sensor can be worn on the skin continuously for a week without discomfort, and is so light and thin that users forget they even have it on, says a group of researchers at the University of Tokyo and their collaborators. The elastic electrode constructed of breathable nanoscale meshes holds promise for the development of noninvasive e-skin devices that can monitor a person’s health continuously over a long period (Nature Nanotechnology, „Inflammation-free, gas-permeable, lightweight, stretchable on-skin electronics with nanomeshes”).
Nanomesh conductor applied to back of hand
Nanomesh conductor applied to back of hand. The nanomesh electrode closely follows the contours of the back of the hand for a perfect fit when attached to the skin. The stretchable device lets the skin breathe naturally, and is so thin and light that wearers forget they even have it on. (Image: Someya Laboratory)
Wearable electronics that monitor heart rate and other vital health signals have made headway in recent years, with next-generation gadgets employing lightweight, highly elastic materials attached directly onto the skin for more sensitive, precise measurements.
However, although the ultrathin films and rubber sheets used in these devices adhere and conform well to the skin, their lack of breathability is deemed unsafe for long-term use: dermatological tests show the fine, stretchable materials prevent sweating and block airflow around the skin, causing irritation and inflammation, which ultimately could lead to lasting physiological and psychological effects.
„We learned that devices that can be worn for a week or longer for continuous monitoring were needed for practical use in medical and sports applications,” says Professor Takao Someya at the University of Tokyo’s Graduate School of Engineering whose research group had previously developed an on-skin patch that measured oxygen in blood.
In the current research, the group developed an electrode constructed from nanoscale meshes containing a water-soluble polymer, polyvinyl alcohol (PVA), and a gold layer—materials considered safe and biologically compatible with the body. The device can be applied by spraying a tiny amount of water, which dissolves the PVA nanofibers and allows it to stick easily to the skin—it conformed seamlessly to curvilinear surfaces of human skin, such as sweat pores and the ridges of an index finger’s fingerprint pattern.
The researchers next conducted a skin patch test—for irritations and skin allergies—on 20 subjects and detected no inflammation on the participants’ skin after they had worn the device for a week. The group also evaluated the permeability, with water vapor, of the nanomesh conductor—along with those of other substrates like ultrathin plastic foil and a thin rubber sheet—and found that its porous mesh structure exhibited superior gas permeability compared to that of the other materials.
Furthermore, the scientists proved the device’s mechanical durability through repeated bending and stretching, exceeding 10,000 times, of a conductor attached on the forefinger; they also established its reliability as an electrode for electromyogram recordings when its readings of the electrical activity of muscles were comparable to those obtained through conventional gel electrodes.
„It will become possible to monitor patients’ vital signs without causing any stress or discomfort,” says Someya about the future implications of the team’s research. In addition to nursing care and medical applications, the new device promises to enable continuous, precise monitoring of athletes’ physiological signals and bodily motion without impeding their training or performance.
Source: University of Tokyo

Super-adsorbant MOF pentru a controla umiditatea(Super-adsorbent MOF to control humidity)

Materialul nostru super-adsorbant are proprietăți unice”, explică Alezi. Două realizări descoperite cu noul MOF (Cr-soc-MOF-1) sunt stabilitatea sa în apă, spre deosebire de multe MOF foarte poroase și porii interni de capacitate mare care pot adsorbi de două ori greutatea MOF ca apă ( vezi imaginea). O altă trăsătură vitală este reversibilitatea ușoară a absorbției apei. Apa adsorbită atunci când nivelurile de umiditate sunt ridicate pot fi eliberate imediat când umiditatea scade. Acest lucru oferă un material ideal pentru controlul umidității în spații restrânse.Acest material nou este un singur produs al angajamentului pe termen lung al lui Eddaoudi de a explora capacitățile MF. „Din cele mai bune cunoștințe, noul nostru MOF de absorbție a apei depășește toate MOF existente în ceea ce privește capacitatea, reversibilitatea și performanța ciclică”, spune Eddaoudi.

Posted: Feb 05, 2018

Super-adsorbent MOF to control humidity

(Nanowerk News) Humidity control is a vital aspect of air conditioning, but high energy requirements make conventional methods expensive and environmentally damaging. Researchers at KAUST have developed a metal-organic framework (MOF) that, within its range of applications, could control humidity in an eco-friendly and cost-effective way (Chem, „Reticular chemistry in action: A hydrolytically stable MOF capturing twice its weight in adsorbed water”).
The crystal structure of the super-adsorbent Cr-soc-MOF-1
The crystal structure of the super-adsorbent Cr-soc-MOF-1, hosting twice its weight as adsorbed water within its extensive network of micropores. The framework is represented in green, red and grey, and water molecules are represented with blue spheres. (Image: Mohamed Eddaoudi)
MOFs encompass metal centers or clusters held in a porous framework by organic linker groups. The key to designing a MOF with specific properties is the ability to control the size and chemical structure of the pores by varying the metal and organic parts within each framework.
Dalal Alezi works in Mohamed Eddaoudi’s research group at KAUST where a wide range of MOFs are being developed for gas separation, purification and chemical catalysis. This work is part of her doctoral research.
„Our super-adsorbent material has unique properties,” explains Alezi. Two breakthrough achievements with the new water-adsorbing MOF (Cr-soc-MOF-1) are its stability in water, unlike many highly porous MOFs, and its high-capacity internal pores that can adsorb twice the weight of the MOF as water (see image). Another vital feature is the easy reversibility of the water uptake. The water adsorbed when humidity levels are high can readily be released when the humidity falls. This yields an ideal material for controlling humidity in restricted spaces.
„Regulating escalating humidity levels, especially indoors and in confined environments, such as aircraft cabins and air-conditioned buildings, is a critical challenge,” says Youssef Belmabkhout, a senior research scientist in Eddaoudi’s group. He adds: „The conventional systems consume large amounts of energy, require intricate design and excessive cost.”
This new material is just one product of Eddaoudi’s long-term commitment to exploring the capabilities of MOFs. „To the best of our knowledge our new water-adsorbing MOF outperforms all existing MOFs in terms of capacity, reversibility and cyclic performance,” says Eddaoudi. The easy reversibility will be crucial for commercial applications. The team have already maintained the exceptional water uptake and release through more than 100 adsorption-desorption cycles.
Eddaoudi also emphasizes that water-adsorbing MOFs are ready to provide effective solutions to challenges other than regulating humidity, such as tackling water scarcity and environmental sustainability in energy-efficient ways. Possibilities include harvesting drinkable water from air and use in water desalination and purification.
The researchers are now working to scale up their water-adsorbing materials in order to demonstrate commercial potential and move into real-world applications.
Source: King Abdullah University of Science and Technology

Luarea energiei solare la margine(Taking solar energy to the edge)

au descoperit o modalitate eficienta de a face panouri solare combinate si dispozitive de emisie de lumina. Mai degrabă decât folosind blocuri de materiale pervoskit hibride, au stratificat mai multe foi subțiri unul peste altul ( Stiinta , „extrem de eficient de disociere a excitonilor interne prin stări de margine în perovskiti 2D stratificate“ și Știință , „Pornesc perovskit Photoresponse“ ).
În acest nou model stratificat, au descoperit importante „stări de margine a stratului”. În aceste stări, energia este foarte conservată. Când este excitat de lumină sau de alte surse, materialul produce energie care nu se disipează instantaneu și poate fi utilizată pentru a încărca bateriile sau pentru a face alte lucrări. Aceasta înseamnă că creează un transportator de lungă durată, gratuit, care poate fi recoltat și manipulat.Hibridele perovskite reprezintă o nouă clasă de materiale cu costuri reduse care pot capta și emite lumină. Acest material poate fi sintetizat în mai multe forme: structuri 3-D în vrac, foi de cristal 2-D și tije 1-D. În particular, compușii stratificați pot fi creați prin stivuirea foilor de cristal 2-D cu straturi organice subțiri între ele.
În comparație cu variantele 3-D în vrac, aceste foi de perovskite sunt stabile intrinsec și reglabile pe scară largă. Prin urmare, aceste foi subțiri pot avea aplicații largi într-o varietate de tehnologii.

Posted: Feb 05, 2018

Taking solar energy to the edge

(Nanowerk News) At the Center for Integrated Nanotechnology (CINT), researchers discovered an efficient way to make combined solar panels and light-emitting devices. Rather than using blocks of hybrid perovskite materials, they layered several thin sheets on top of each other (Science, „Extremely efficient internal exciton dissociation through edge states in layered 2D perovskites”and Science, „Powering up perovskite photoresponse”).
In this new layered pattern, they discovered important “layer-edge states.” In these states, energy is highly conserved. When excited by light or other sources, the material produces energy that doesn’t instantly dissipate and can be used to charge batteries or do other work. That is, it creates long-lived, free charge carriers that can be harvested and manipulated.
An artistic rendering shows the dissociation of electron-hole pairs to free carriers at crystal edges resulting in efficient solar energy and light emission
An artistic rendering shows the dissociation of electron-hole pairs (excitons) to free carriers at crystal edges resulting in efficient solar energy (>12 percent) and light emission (>30 percent). Dissociated carriers captured and located at the edges have lower energy and last longer. (Image: Jean-Christophe Blancon, Los Alamos National Laboratory)
Compared to blocks of material, layered sheets of perovskites offer a host of benefits. The sheets are more chemically stable, more environmentally friendly, and more tunable to fit the needs of new applications or experiments. Discovery of edge states opens new avenues for designing and fabricating efficient electronic devices which collect and emit light. These devices include low-cost solar cells, LEDs, laser diodes, and detectors.
Hybrid perovskites are a new class of low-cost materials that can capture and emit light. This material can be synthesized in several forms: bulk 3-D structures, 2-D crystal sheets, and 1-D rods. In particular, layered compounds can be created by stacking 2-D crystal sheets with thin organic layers in between.
Compared to bulk 3-D variations, these sheets of perovskites are intrinsically stable and widely tunable. Therefore, these thin sheets may have broad applications in a variety of technologies.
In this study, scientists from CINT as well as international collaborators describe a strategy to layer sheets of 2-D perovskites to drastically enhance the material’s optoelectronic properties. They found that in materials with three or more layers, charged particles (electrons and holes) become trapped at low-energy states near the edge of the crystal layers.
These carriers exhibit a 5-fold increase in their lifetime and do not lose energy to heat, resulting in tremendous improvements in efficiency for light-capturing devices.
On the flip side, devices that emit light are also tremendously more effective because trapped carriers can recombine very efficiently.
These results address a long-standing problem not just for the perovskite family but also for a large group of materials. Often, the edges and surface states of materials can degrade the optoelectronic properties.
Now, the structure of these materials can be chemically designed and engineered to achieve efficient flow of charge and energy leading to high-efficiency optoelectronic devices.
Source: U.S. Department of Energy, Office of Science

Dioxid de vanadiu: Un material revoluționar pentru electronica de mâine(Vanadium dioxyde: A revolutionary material for tomorrow’s electronics)

O caracteristică cheie a acestui compus este că se comportă ca un izolator la temperatura camerei, dar ca un conductor la temperaturi de peste 68 ° C. Acest comportament, cunoscut și sub numele de tranziția izolatoarelor metalice, este studiat într-un proiect ambițios al UE Orizont 2020 numit Switch Phase-Change. EPFL a fost aleasă pentru a coordona proiectul în urma unui proces de selecție provocator.

Posted: Feb 05, 2018

Vanadium dioxyde: A revolutionary material for tomorrow’s electronics

(Nanowerk News) First came the switch. Then the transistor. Now another innovation stands to revolutionize the way we control the flow of electrons through a circuit: vanadium dioxide (VO2). A key characteristic of this compound is that it behaves as an insulator at room temperature but as a conductor at temperatures above 68°C. This behavior – also known as metal-insulator transition – is being studied in an ambitious EU Horizon 2020 project called Phase-Change Switch. EPFL was chosen to coordinate the project following a challenging selection process.
Vanadium Dioxide Chip
This is a Vanadium Dioxide chip developed at EPFL’s NANOLAB. (Image: Jamani Caillet, EPFL)
The project will last until 2020 and has been granted €3.9 million of EU funding. Due to the array of high-potential applications that could come out of this new technology, the project has attracted two major companies – Thales of France and the Swiss branch of IBM Research – as well as other universities, including Max-Planck-Gesellschaft in Germany and Cambridge University in the UK. Gesellschaft für Angewandte Mikro- und Optoelektronik (AMO GmbH), a spin-off of Aachen University in Germany, is also taking part in the research.
Scientists have long known about the electronic properties of VO2 but haven’t been able to explain them until know. It turns out that its atomic structure changes as the temperature rises, transitioning from a crystalline structure at room temperature to a metallic one at temperatures above 68°C. And this transition happens in less than a nanosecond – a real advantage for electronics applications.
„VO2 is also sensitive to other factors that could cause it to change phases, such as by injecting electrical power, optically, or by applying a THz radiation pulse,” says Adrian Ionescu, the EPFL professor who heads the school’s Nanoelectronic Devices Laboratory (Nanolab) and also serves as the Phase-Change Switch project coordinator.

The challenge: reaching higher temperatures
However, unlocking the full potential of VO2 has always been tricky because its transition temperature of 68°C is too low for modern electronic devices, where circuits must be able to run flawlessly at 100°C.
But two EPFL researchers – Ionescu from the School of Engineering (STI) and Andreas Schüler from the School of Architecture, Civil and Environmental Engineering (ENAC) – may have found a solution to this problem, according to their joint research published in Applied Physics Letters in July 2017. They found that adding germanium to VO2 film can lift the material’s phase change temperature to over 100°C.
Even more interesting findings from the Nanolab – especially for radiofrequency applications – were published in IEEE Access („Vanadium Oxide bandstop tunable filter for Ka frequency bands based on a novel reconfigurable spiral shape defected ground plane CPW”).
For the first time ever, scientists were able to make ultra-compact, modulable frequency filters. Their technology also uses VO2 and phase-change switches, and is particularly effective in the frequency range crucial for space communication systems (the Ka band, with programmable frequency modulation between 28.2 and 35 GHz).

Neuromorphic processors and autonomous vehicles
These promising discoveries are likely to spur further research into applications for VO2 in ultra-low-power electronic devices. In addition to space communications, other fields could include neuromorphic computing and high-frequency radars for self-driving cars.
Source: Ecole Polytechnique Fédérale de Lausanne

Termenul limită se apropie de contractul de asistență acordat de DARPA de 850 milioane USD(Agenția de cercetare a redus valoarea minimă a comenzii înainte de termenul limită de propunere)

Agenția de cercetare a redus valoarea minimă a comenzii înainte de termenul limită de propunere;Există o mulțime de oameni inteligenți la DARPA care lucrează la o mulțime de tehnologii interesante și avansate

Deadline

Cercetătorii dezvoltă un nou design de suprafață inspirat de pielea de șarpe(

Rezultatele lor sugerează o platformă versatilă atât pentru manipularea fluidelor, cât și pentru cele ușoare, atât la nivel micro, cât și la nivel macroscopic. Aplicațiile potențiale pot fi găsite în microfluidica digitală, dispozitive biomedicale, jaluzele virtuale, suprafețe de camuflaj și rețele de micromirror. cercetătorii săi au fost capabili să proiecteze, să caracterizeze și să analizeze o gamă largă de funcții, cum ar fi umectarea reglabilă, manipularea picăturilor, transmisia optică tunabilă și colorarea structurală, prin încorporarea unei game largi de scale – siliciu gol, și cântare fotonice de cristal – în configurații atât în ​​plan, cât și în afara planului.

Posted: Feb 02, 2018

Researchers develop new surface design inspired by snake skin

(Nanowerk News) Assistant Professor Seok Kim and graduate students Zining Yang and Jun Kyu Park have developed a design construct inspired in part by the surface of butterflies and snakes, where flexible skins are fully covered by rigid, discrete scales.
Their work was recently featured on the cover of Small („Magnetically Responsive Elastomer-Silicon Hybrid Surfaces for Fluid and Light Manipulation”).
Scales Surface Screen Cap
Seok Kim Lab develops new surface design inspired by snake skin. (Image: University of Illinois Department of Mechanical Science and Engineering)
Their new surface design features rigid scales assembled into soft, ferromagnetic micropillars on a flexible substrate in a predesigned manner by transfer printing-based deterministic assembly. The nanostructured silicon scales on the magnetically responsive elastomer micropillar array enables fluid and light manipulation. The functional properties of the surface are dictated by the scales’ patterns, while the micropillar array is magnetically actuated with large-range, instantaneous, and reversible deformation.
Kim and his researchers were able to design, characterize, and analyze a wide range of functions, such as tunable wetting, droplet manipulation, tunable optical transmission, and structural coloration, by incorporating a wide range of scales–bare silicon, black silicon, and photonic crystal scales–in both in-plane and out-of-plane configurations.
Magnetically response materials like soft elastomers loaded with magnetic particles, are desirable for their real-time manipulation of fluid, light, solid particles, and living cells – thanks to their instantaneous structural tenability under a magnetic field. However, due to the fabrication process, most existing surfaces of this kind are limited in their functional ability.
Compared with common responsive surface with simple design (the magnetic micropillar array), the surface developed in our work not only has enhanced performance in directional liquid spreading and optical transmission tuning, but also enables novel functions such as droplet manipulation and dynamic structural coloration,” said Yang, PhD candidate and first author of the study.
Their results suggest a versatile platform for both fluid and light manipulations at both the micro and macroscale. Potential applications can be found in digital microfluidics, biomedical devices, virtual blinds, camouflage surfaces, and micromirror arrays. Further work could also result in more biomimetic functionalities such as robotic locomotion, swimming, self-cleaning, and solid object manipulation. Their design could also be integrated with active devices such as solar cells, light emitting diodes, and lasers as scales to form novel flexible optoelectronics.
Kim is a leading scientist in advanced transfer printing and transfer printing-based microassembly.
Source: University of Illinois College of Engineering