Un concurs de departamente a avansat cinci sisteme de avertizare timpurie destinate detectării atacurilor biologice;sistem pentru a menține atacurile biologice la distanță
Noul sistem, numit un rezonator termic, ar putea permite funcționarea continuă, de ani de zile a sistemelor de teledetecție, de exemplu, fără a necesita alte surse de alimentare sau baterii, spun cercetătorii.echipa a creat o combinație de materiale adaptată cu atenție. Structura de bază este o spumă de metal, realizată din cupru sau nichel, care este apoi acoperită cu un strat de grafen pentru a asigura o conductivitate termică și mai mare. Apoi, spuma este infuzată cu un fel de ceară numită octadecan, un material cu schimbare de fază, care se schimbă între solid și lichid într-un anumit interval de temperatură ales pentru o anumită aplicație.
| Posted: Feb 15, 2018 | |
System draws power from daily temperature swings(Nanowerk News) Thermoelectric devices, which can generate power when one side of the device is a different temperature from the other, have been the subject of much research in recent years. Now, a team at MIT has come up with a novel way to convert temperature fluctuations into electrical power. Instead of requiring two different temperature inputs at the same time, the new system takes advantage of the swings in ambient temperature that occur during the day-night cycle. |
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| The new system, called a thermal resonator, could enable continuous, years-long operation of remote sensing systems, for example, without requiring other power sources or batteries, the researchers say. | |
| The findings are being reported in the journal Nature Communications („Ultra-high thermal effusivity materials for resonant ambient thermal energy harvesting”), in a paper by graduate student Anton Cottrill, Carbon P. Dubbs Professor of Chemical Engineering Michael Strano, and seven others in MIT’s Department of Chemical Engineering. | |
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| The team’s test device, which has been deployed on the roof of an MIT building for several months, was used to prove the principle behind their new energy-harvesting concept. The test device is the black box at right, behind a weather-monitoring system (white) and a set of test equipment to monitor the device’s performance (larger black case at left). (Image: Justin Raymond) | |
| “We basically invented this concept out of whole cloth,” Strano says. “We’ve built the first thermal resonator. It’s something that can sit on a desk and generate energy out of what seems like nothing. We are surrounded by temperature fluctuations of all different frequencies all of the time. These are an untapped source of energy.” | |
| While the power levels generated by the new system so far are modest, the advantage of the thermal resonator is that it does not need direct sunlight; it generates energy from ambient temperature changes, even in the shade. That means it is unaffected by short-term changes in cloud cover, wind conditions, or other environmental conditions, and can be located anywhere that’s convenient — even underneath a solar panel, in perpetual shadow, where it could even allow the solar panel to be more efficient by drawing away waste heat, the researchers say. | |
| The thermal resonator was shown to outperform an identically sized, commercial pyroelectric material — an established method for converting temperature fluctuations to electricity — by factor of more than three in terms of power per area, according to Cottrill. | |
| The researchers realized that to produce power from temperature cycles, they needed a material that is optimized for a little-recognized characteristic called thermal effusivity — a property that describes how readily the material can draw heat from its surroundings or release it. Thermal effusivity combines the properties of thermal conduction (how rapidly heat can propagate through a material) and thermal capacity (how much heat can be stored in a given volume of material). In most materials, if one of these properties is high, the other tends to be low. Ceramics, for example, have high thermal capacity but low conduction. | |
| To get around this, the team created a carefully tailored combination of materials. The basic structure is a metal foam, made of copper or nickel, which is then coated with a layer of graphene to provide even greater thermal conductivity. Then, the foam is infused with a kind of wax called octadecane, a phase-change material, which changes between solid and liquid within a particular range of temperatures chosen for a given application. | |
| A sample of the material made to test the concept showed that, simply in response to a 10-degree-Celsius temperature difference between night and day, the tiny sample of material produced 350 millivolts of potential and 1.3 milliwatts of power — enough to power simple, small environmental sensors or communications systems. | |
| “The phase-change material stores the heat,” says Cottrill, the study’s lead author, “and the graphene gives you very fast conduction” when it comes time to use that heat to produce an electric current. | |
| Essentially, Strano explains, one side of the device captures heat, which then slowly radiates through to the other side. One side always lags behind the other as the system tries to reach equilibrium. This perpetual difference between the two sides can then be harvested through conventional thermoelectrics. The combination of the three materials — metal foam, graphene, and octadecane — makes it “the highest thermal effusivity material in the literature to date,” Strano says. | |
| While the initial testing was done using the 24-hour daily cycle of ambient air temperature, tuning the properties of the material could make it possible to harvest other kinds of temperature cycles, such as the heat from the on-and-off cycling of motors in a refrigerator, or of machinery in industrial plants. | |
| “We’re surrounded by temperature variations and fluctuations, but they haven’t been well-characterized in the environment,” Strano says. This is partly because there was no known way to harness them. | |
| Other approaches have been used to try to draw power from thermal cycles, with pyroelectric devices, for example, but the new system is the first that can be tuned to respond to specific periods of temperature variations, such as the diurnal cycle, the researchers say. | |
| These temperature variations are “untapped energy,” says Cottrill, and could be a complementary energy source in a hybrid system that, by combining multiple pathways for producing power, could keep working even if individual components failed. The research was partly funded by a grant from Saudi Arabia’s King Abdullah University of Science and Technology (KAUST), which hopes to use the system as a way of powering networks of sensors that monitor conditions at oil and gas drilling fields, for example. | |
| “They want orthogonal energy sources,” Cottrill says — that is, ones that are entirely independent of each other, such as fossil fuel generators, solar panels, and this new thermal-cycle power device. Thus, “if one part fails,” for example if solar panels are left in darkness by a sandstorm, “you’ll have this additional mechanism to give power, even if it’s just enough to send out an emergency message.” | |
| Such systems could also provide low-power but long-lasting energy sources for landers or rovers exploring remote locations, including other moons and planets, says Volodymyr Koman, an MIT postdoc and co-author of the new study. For such uses, much of the system could be made from local materials rather than having to be premade, he says. | |
| This approach “is a novel development with a great future,” says Kourosh Kalantar-zadeh, a distinguished professor of engineering at RMIT University in Melbourne, Australia, who was not involved in this work. “It can potentially play an unexpected role in complementary energy harvesting units.” | |
| He adds, “To compete with other energy harvesting technologies, always higher voltages and powers are demanded. However, I personally feel that it is quite possible to gain a lot more out of this by investing more into the concept. … It is an attractive technology which will be potentially followed by many others in the near future.” |
| Source: By David L. Chandler, MIT |
Exoskeletonele mobile sunt mașini portabile care sunt mobile și alimentate cu ajutorul unui sistem de hidraulică, motoare electrice, pneumatice, pârghii sau o combinație de tehnologii care permit mișcarea membrelor cu rezistență și rezistență
armata va lua doi Humvee înarmați, autonomi, pe o pistă pentru a le testa și a le certifica drept vehicule de luptă, ceea ce le va face primele vehicule de teren robotizate pentru a fi OK
au dezvoltat noi materiale nețesute care sunt conductive din punct de vedere electric, precum și flexibile și respirabile. Acest lucru deschide calea pentru hainele confortabile de înaltă tehnologie care, de exemplu, transformă lumina soarelui în căldură, pun la dispoziție dispozitive electronice portabile cu electricitate sau conțin senzori pentru antrenament de fitness.au reușit să producă materiale nețesute conductive din punct de vedere electric care au toate celelalte caracteristici pe care le-ați aștepta de la îmbrăcămintea potrivită pentru utilizarea zilnică. Materialele sunt flexibile și, astfel, se adaptează mișcărilor și modificărilor posturii. În plus, ele sunt permeabile la aer, ceea ce înseamnă că nu interferează cu respirația naturală a pielii.
| Posted: Feb 14, 2018 | |
Smart and comfortable new nanocomposite textiles for high-tech clothing(Nanowerk News) Uncomfortable, rigid, with low air permeability: textile materials capable of conducting electricity can be awkward for day-to-day use. However, researchers at the University of Bayreuth, Donghua University in Shanghai, and Nanjing Forestry University have now developed new nonwoven materials that are electrically conductive as well as flexible and breathable. This paves the way for comfortable high-tech clothes which, for example, convert sunlight to warmth, supply wearable electronic devices with electricity, or contain sensors for fitness training. |
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| The scientists have published their findings in the journal npj Flexible Electronics („Polymer nanofibre composite nonwovens with metal-like electrical conductivity”). | |
| Prof. Dr. Andreas Greiner’s team of researchers at the University of Bayreuth and their Chinese partners have succeeded in producing electrically conductive nonwovens which have all the other characteristics you would expect from clothing that is suitable for daily use. The materials are flexible, and thus adapt to movements and changes in posture. In addition, they are air-permeable, meaning they do not interfere with the natural breathing of the skin. | |
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| Prof. Dr. Andreas Greiner (left) and Prof. Dr. Seema Agarwal (right) with equipment for electrospinning at the University of Bayreuth. With backlighting, one can see the thin fibres from which nonwoven materials are formed. | |
| The combination of these properties is based on a special production process. In contrast to common methods of production, metal wires were not inserted into finished textiles. Rather, the scientists modified classical electro-spinning, which has been used to produce nonwovens for many years: short electro-spun polymer fibres and small amounts of tiny silver wires with a diameter of only 80 nanometres are mixed in a liquid. Afterwards, they are filtered, dried, and briefly heated up. If the composition is right, the resulting nonwoven material exhibits a very high degree of electrical conductivity. | |
| This opens up a whole range of possibilities for innovative applications, especially in the area of smart clothes (i.e. wearables). Everyday clothing, for example, can be equipped with solar cells such that the captured sunlight is converted to warmth, heating up the textiles themselves. Mobile phones, cameras, mini-computers, and other wearable electronic devices could be charged by plugging them into the textiles. Sensors installed in the clothes could provide athletes and trainers with important fitness and health data or could give family and friends information on its location. | |
| “In addition to articles of clothing, similar functions could also just as easily be installed in textile materials for use in seats and instruments in cars or airplanes,” explained Prof. Dr. Andreas Greiner, Chair of Macromolecular Chemistry II at the University of Bayreuth. | |
| “Our approach, which takes the production of conductive textiles as its basis, can in principle be applied to many different systems,” added Steffen Reich, doctoral researcher and lead author of the new study. As an example, he cites current Bayreuth research projects on microbial fuel cells, which could eventually be used as electrodes in such nonwoven materials. | |
| The research findings that were published in npj Flexible Electronics resulted from close cooperation between the University of Bayreuth, Donghua University in Shanghai, and Nanjing Forestry University. It was only two years ago that the University of Bayreuth signed a cooperation agreement with Donghua University, which has had a research priority on the research and development of textiles since the establishment of the institution. The mutual exchange in research and teaching that was agreed on is now beginning to bear fruit. |
| Source: University of Bayreuth |
proliferarea radiourilor, a dispozitivelor inteligente portabile, a GPS-ului și a altor dispozitive electronice personale care susțin operațiunea „viitorului soldat” promite examinarea modalităților de a satisface cererea de energie și de energie la nivelul soldaților;
Incomod, rigid, cu permeabilitate scăzută a aerului: materialele textile capabile să conducă electricitatea pot fi dificil de utilizat pentru utilizarea zilnică;fibrele subțiri din care se formează materiale nețesute;
Combinația acestor proprietăți se bazează pe un proces de producție special
demonstrează modul în care senzorii purtați pot să urmărească mișcarea ochilor;inginerii au transformat hârtia de țesut, asemănătoare cu cea a toaletei, într-un nou tip de senzor care poate detecta un impuls, o clipire a ochiului și alte mișcări umane
au transformat hârtia de țesut – similar cu cea a toaletei – într-un nou tip de senzor care poate detecta un puls, o clipire a ochiului și alte mișcări umane. Senzorul este ușor, flexibil și ieftin, cu aplicații potențiale în domeniul sănătății, al divertismentului și al roboticii.rată că, prin ruperea hârtiei absorbante cu nanocompozite și prin ruperea fibrelor de hârtie, hârtia acționează ca un senzor . Acesta poate detecta o batai inimii, forta degetului, miscare a degetului, miscare a ochilor si multe altele, a spus Jae-Hyun Chung, profesor asociat UW de inginerie mecanica si autor principal al cercetarii.
| Posted: Feb 13, 2018 | |
Tissue paper sensors show promise for health care, entertainment, robotics(Nanowerk News) University of Washington engineers have turned tissue paper – similar to toilet tissue – into a new kind of wearable sensor that can detect a pulse, a blink of an eye and other human movement. The sensor is light, flexible and inexpensive, with potential applications in health care, entertainment and robotics. |
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| The technology, described in a paper in the journal Advanced Materials Technologies („Fracture-Induced Mechanoelectrical Sensitivities of Paper-Based Nanocomposites”), shows that by tearing tissue paper that’s loaded with nanocomposites and breaking the paper’s fibers, the paper acts as a sensor. It can detect a heartbeat, finger force, finger movement, eyeball movement and more, said Jae-Hyun Chung, a UW associate professor of mechanical engineering and senior author of the research. | |
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| University of Washington graduate student, Jinyuan Zhang, demonstrates how eye movement is tracked with a tissue paper sensor. | |
| “The major innovation is a disposable wearable sensor made with cheap tissue paper,” said Chung. “When we break the specimen, it will work as a sensor.” | |
| These small, Band Aid-sized sensors could have a variety of applications in various fields. For example, monitoring a person’s gait or the movement of their eyes can be used to inspect brain function or a game player’s actions. The sensor could track how a special-needs child walks in a home test, sparing the child the need for hospital visits. Or the sensors could be used in occupational therapy for seniors. | |
| “They can use these sensors and after one-time use, they can be thrown away,” said Chung. | |
| In their research, the scientists used paper similar to toilet tissue. The paper – nothing more than conventional paper towels – is then doused with carbon nanotube-laced water. Carbon nanotubes are tiny materials that create electrical conductivity. Each piece of tissue paper has both horizontal and vertical fibers, so when the paper is torn, the direction of the tear informs the sensor of what’s happened. To trace eye movement, they’re attached to a person’s reading glasses. | |
| For now, the work has been contained to a laboratory, and researchers are hoping to find a suitable commercial use. A provisional patent was filed in December 2017. |
| Source: University of Washington | |
anunță săptămâna aceasta că au construit un film subțire stabil din fier, cobalt și mangan, care se mândrește cu literele fizice aplicate ( „momente mari în filmul subțire al aliajului FexCoyMnz din aliajele ternare” ) un moment atomic mediu cu 50% mai mare decât limita Slater-Pauling. Realizată printr-o tehnică cunoscută sub denumirea de epitaxie cu fascicule moleculare (MBE), aliajul cubic (bcc) centrat pe corp ternar prezintă o densitate de magnetizare de 3,25 magnetoni Bohr pe atom, depășind maximul considerat anterior de 2,45.
| Posted: Feb 13, 2018 | |
Three’s company: New alloy sets magnetism benchmark(Nanowerk News) The burgeoning field of spintronics leverages electron spins – as opposed to their charge – to enhance solid-state devices like hard drives and cell phone components by prolonging battery life. Spintronic developments, however, are increasingly running up against a barrier known as the Slater-Pauling limit, the maximum for how tightly a material can pack its magnetization. Now, a new thin film is poised to break through this decades-old benchmark. |
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| A team of researchers from Montana State University and Lawrence Berkeley National Laboratory announces this week in Applied Physics Letters („Large moments in bcc FexCoyMnz ternary alloy thin films”), that they constructed a stable thin film made from iron, cobalt and manganese that boasts an average atomic moment potentially 50 percent greater than the Slater-Pauling limit. Made with a technique known as molecular beam epitaxy (MBE), the ternary body-centered cubic (bcc) alloy features a magnetization density of 3.25 Bohr magnetons per atom, besting the previously considered maximum of 2.45. | |
| „What we have is a potential breakthrough in one of the most important parameters of magnetic materials,” said Yves Idzerda, an author on the paper from Montana State University. „Large magnetic moments are like the strength of steel – the bigger the better.” | |
| The Slater-Pauling curve describes magnetization density for alloys. For decades, iron-cobalt (FeCo) binary alloys have reigned supreme, posting a maximum average atomic moment of 2.45 Bohr magnetons per atom and defining the current limit for stable alloy magnetization density. Previously, researchers mixed FeCo alloys with high-magnetic-moment transition metals, like manganese. When these ternary alloys are made, however, they lose much of their bcc structure, a key component to their high magnetism. | |
| Instead, this team turned to MBE, a meticulous technique akin to draping a substrate with beads of individual metal atoms, one layer at a time, to create a 10-20 nanometer film of Fe9Co62Mn29. Roughly 60 percent of the available compositions kept the bcc structure as a thin film, compared to only 25 percent in bulk. | |
| To better understand the alloy’s composition and structure, the group used X-ray absorption spectroscopy and reflection high-energy-electron diffraction. The X-ray magnetic circular dichroism results showed that the new material yielded an average atomic moment of 3.25 Bohr magnetons per atom. When tested with a more standard vibrating sample magnetometry, even though this magnetization density dropped, it was still significantly above the Slater-Pauling limit – 2.72. | |
| Idzerda said this discrepancy will provide areas of future research, adding that the interface between manganese and the substrate within the crystal might account for the gap. | |
| „I have guarded optimism for this because the technique we used is a little bit nonstandard and we have to convince the community of this material’s performance,” Idzerda said. | |
| Idzerda and his team will now investigate the robustness of iron-cobalt-manganese alloys, and more efficient fabrication techniques. They also plan to explore how molecular beam epitaxy might lead to other highly magnetic thin films, potentially mixing together four or more transition metals. |
| Source: American Institute of Physics |
investighează modalitățile de a scrie modele de grafen în produsele alimentare și în alte materiale pentru a încorpora rapid etichetele și senzorii conductivi de identificare în produsele în sine.separată pe mâncare, ci pe mâncarea în sine”.
Multi pași laser cu un fascicul defocalizat au permis cercetătorilor să scrie modelele LIG în pânză, hârtie, cartofi, coji de nucă de cocos și plută, precum și toast. (Pâinea este prăjită mai întâi pentru a „carboniza” suprafața.) Procesul se întâmplă în aer la temperaturi ambiante.
„În unele cazuri, lexarea multiplă creează o reacție în două etape”, a spus Tour. In primul rand, laserul transforma fototeramatic suprafata tinta in carbon amorf. Apoi, pe trecerea ulterioara a laserului, absorbtia selectiva a luminii infrarosii transforma carbonul amorf in LIG, descoperind ca lungimea de unda are importanta.Acest lucru are aplicații pentru a pune urme conductive pe îmbrăcăminte, indiferent dacă doriți să încălziți îmbrăcămintea sau să adăugați un senzor sau un model conductiv”,
| Posted: Feb 13, 2018 | |
Graphene on toast, anyone? (w/video)(Nanowerk News) Rice University scientists who introduced laser-induced graphene (LIG) have enhanced their technique to produce what may become a new class of edible electronics. |
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| The Rice lab of chemist James Tour, which once turned Girl Scout cookies into graphene, is investigating ways to write graphene patterns onto food and other materials to quickly embed conductive identification tags and sensors into the products themselves. | |
| „This is not ink,” Tour said. „This is taking the material itself and converting it into graphene.” | |
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| Laser-induced graphene is a highly conductive addition to a piece of bread. A Rice University lab is using an industrial laser to write graphene patterns on everyday objects, including food, cloth, cardboard and wood. (Image: Jeff Fitlow/Rice University) | |
| The process is an extension of the Tour lab’s contention that anything with the proper carbon content can be turned into graphene. In recent years, the lab has developed and expanded upon its method to make graphene foam by using a commercial laser to transform the top layer of an inexpensive polymer film. | |
| The foam consists of microscopic, cross-linked flakes of graphene, the two-dimensional form of carbon. LIG can be written into target materials in patterns and used as a supercapacitor, an electrocatalyst for fuel cells, radio-frequency identification (RFID) antennas and biological sensors, among other potential applications. | |
| The new work reported in the American Chemical Society journal ACS Nano(DOI:10.1021/acsnano.7b08539″) demonstrated that laser-induced graphene can be burned into paper, cardboard, cloth, coal and certain foods, even toast. | |
| „Very often, we don’t see the advantage of something until we make it available,” Tour said. „Perhaps all food will have a tiny RFID tag that gives you information about where it’s been, how long it’s been stored, its country and city of origin and the path it took to get to your table.” He said LIG tags could also be sensors that detect E. coli or other microorganisms on food. „They could light up and give you a signal that you don’t want to eat this,” Tour said. „All that could be placed not on a separate tag on the food, but on the food itself.” | |
| Multiple laser passes with a defocused beam allowed the researchers to write LIG patterns into cloth, paper, potatoes, coconut shells and cork, as well as toast. (The bread is toasted first to „carbonize” the surface.) The process happens in air at ambient temperatures. | |
| „In some cases, multiple lasing creates a two-step reaction,” Tour said. „First, the laser photothermally converts the target surface into amorphous carbon. Then on subsequent passes of the laser, the selective absorption of infrared light turns the amorphous carbon into LIG. We discovered that the wavelength clearly matters.” | |
| The researchers turned to multiple lasing and defocusing when they discovered that simply turning up the laser’s power didn’t make better graphene on a coconut or other organic materials. But adjusting the process allowed them to make a micro supercapacitor in the shape of a Rice „R” on their twice-lased coconut skin. | |
| Defocusing the laser sped the process for many materials as the wider beam allowed each spot on a target to be lased many times in a single raster scan. That also allowed for fine control over the product, Tour said. Defocusing allowed them to turn previously unsuitable polyetherimide into LIG. | |
| „We also found we could take bread or paper or cloth and add fire retardant to them to promote the formation of amorphous carbon,” said Rice graduate student Yieu Chyan, co-lead author of the paper. „Now we’re able to take all these materials and convert them directly in air without requiring a controlled atmosphere box or more complicated methods.” | |
| The common element of all the targeted materials appears to be lignin, Tour said. An earlier study relied on lignin, a complex organic polymer that forms rigid cell walls, as a carbon precursor to burn LIG in oven-dried wood. Cork, coconut shells and potato skins have even higher lignin content, which made it easier to convert them to graphene. | |
| Tour said flexible, wearable electronics may be an early market for the technique. „This has applications to put conductive traces on clothing, whether you want to heat the clothing or add a sensor or conductive pattern,” he said. |
| Source: By Mike Williams, Rice University |
