O piele inteligentă analogică care este auto-alimentată(An analogue smart skin that is self-powered )

„Pielea inteligentă analogică are în mod evident avantaje în ceea ce privește rezoluția și consumul de energie”, spune ea. „Sper ca munca noastră să atragă mai multă atenție pe domeniul pielii inteligente analogice. În plus, va contribui la zonele de inteligență artificială și electronică portabilă, deoarece senzorul de înaltă rezoluție auto-alimentat oferă o soluție pentru aplicații inteligente pentru piele

Posted: Apr 08, 2016

An analogue smart skin that is self-powered

(Nanowerk Spotlight) In order to make robots and robotic technology more human-like and more human-friendly, smart skin technology is a critical element that helps robots sense the world. These electronic or smart skins could help machines to accurately perceive the environment and better assist human owners.However, conventional smart skins – no matter if they are based on resistance, capacitance or transistors – all need a power supply. It’s kind of awkward for users to have a high-tech, state-of-the-art thin, flexible and light-weight smart skin and have to power it with a hard and heavy battery which can just work for hours.Furthermore, in conventional smart skins higher resolution always means higher energy consumption and complex circuits. These two aspects need to be carefully balanced to result in a practical device. So the obvious question is: Is it possible to achieve higher resolution and at the same time reduce energy consumption?A self-powered smart skin as the one just recently developed by a team of Chinese researchers fundamentally solves this problem. In this work, the scientists combine the triboelectric effect and planar electrostatic induction and apply it in a subtle device structure for the first time to create a self-powered analogue smart skin.Structure of analogue smart skinsStructure of analogue smart skins. (a) Schematic diagram of an analogue smart skin. (b) Optical image of the transparent, flexible, and lightweight smart skin. The smart skin with a honey bee landing on it will not deform the peony. (c) SEM image of microstructures on the PDMS film. (d) SEM image of the silver nanowire electrodes. (Reprinted with permission by American Chemical Society)Reporting their findings in ACS Nano („Self-Powered Analogue Smart Skin”), a team led by Prof. Haixia Zhang at the National Key Laboratory of Science and Technology on Micro/Nano Fabrication, Peking University, presents a self-powered analogue smart skin to detect location as well as contact velocity, based on a single-electrode contact electrification effect and planar electrostatic induction.In this paper, the team presents two significant achievements. The first is that their smart skin is intrinsically self-powered.”We use spontaneous triboelectric charges, combined with planar electrostatic induction, to sense the touch applied on the smart skin,” Zhang explains to Nanowerk. „Triboelectric charges occur in our daily life everywhere when two surfaces touch each other. And when the charged surface approaches a metal block (or electrode) it will induce the opposite charge, which is the so-called ‘electrostatic induction’ effect.”The beauty of this approach is that it makes use of the charges from triboelectric effect – which exist everywhere. Imagine a scenario, when you want to drink some coffee: you walk towards a table, and by doing so the opposite charges will be generated on the surface of shoes and ground respectively; you pick up the cup to drink, and the opposite charges will be generated on the skin of your palm and the handle of the cup; furthermore, even swallowing the coffee will generate charges on the surface of your digestive tract and the coffee.The Chinese researchers utilize these spontaneous – but often be ignored – charges to make their smart skin completely self-powered.The intensity of the electrostatic induction effect depends on the distance between the charged surface and the metal electrode. The scientists use fixed electrodes to detect the intensity of the electrostatic induction effect, allowing them to confirm the location based on the relative intensity.That way, no extra power supply is required for operating the analogue smart skin.The second achievement is that only four electrodes are necessary to achieve millimeter bi-dimensional resolution (precision) because of the utilization of analogue localizing method to sense the touch stimulation.”Compared with the previous works (see references 1-3 below), this smart skin reduces the number of electrodes remarkably,” Zhang points out. „This helps a lot to reduce the complexity of the signal processing circuit. Although using less electrodes, our smart skins achieve 1.9 mm resolution, much better than previous results.”She notes that, compared with digital smart skins which have been studied extensively, analogue smart skins still need more in-depth study.”Analogue smart skins have obviously advantages at resolution and energy consumption,” she says. „I hope our work can draw more attention to the field of analogue smart skins. Furthermore, it will contribute to the areas of artificial intelligence and portable electronics as the self-powered high-resolution sensor offers a solution for smart skin applications.”Use of smart skin on an artificial handUse of smart skin on an artificial hand. (a) Photograph of an artificial hand covered by two-dimensional analogue smart skins on the curved back of the hand and one-dimensional analogue smart skins on the middle finger. (b) Voltage output when a honey bee approaches and leaves the two-dimensional smart skin swiftly. (c,d) Voltage ratios of electrodes a-d. (e) Voltage output when the two-dimensional smart skin on the artificial hand is touched. (f) Location result of analogue smart skins. The testing point is (2.50, 2.50), and the result is (2.53, 2.50), with a slight deviation of only 0.3 mm. (Reprinted with permission by American Chemical Society) (click on image to enlarge)Going forward, the team will work on the stretchability of their smart skin (the current version is not stretchable) and on improving the resolution. According to the team, due to the theoretically infinite resolution, there still is plenty of room to improve on the current performance. Furthermore, they will try to integrate more sensing parameters as well as signal transmission in the design.Last but not the least, they will explore approaches to shield the smart skin from environmental interference, which is critical for practical applications.Zhang notes that the current device design provides opportunities for including additional sensing capabilities such as temperature, contact velocity, or gas composition.References1) Takao Someya’s Group,36 electrodes for 64 square centimeter smart skins. Kaltenbrunner, M, et al. „An ultra-lightweight design for imperceptible plastic electronics.” Nature 499.499(2013):458-63.2) Zhenan Bao‘s Group, 16 electrodes for 4 square centimeter smart skins. Lipomi, Darren J., et al. „Skin-like pressure and strain sensors based on transparent elastic films of carbon nanotubes.” Nature Nanotechnology 6.12(2011):788-792.3) Do Hwan Kim’s Group, 14 electrodes for 16 square centimeter smart skins. Kim, So Young, et al. „Highly Sensitive and Multimodal All-Carbon Skin Sensors Capable of Simultaneously Detecting Tactile and Biological Stimuli.” Advanced Materials 27.28(2015):4178-4185.By Michael is author of two books by the Royal Society of Chemistry: Nano-Society: Pushing the Boundaries of Technology and Nanotechnology: The Future is Tiny. Copyright © Nanowerk

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Punctele cuantice sporesc conversia de la lumină la curent în semiconductori din metal de tip dichalcogenid stratificat( Quantum dots enhance light-to-current conversion in layered metal dichalcogenide semiconductors)

Ideea de materiale stratificate bidimensionale«dopaj»cu puncte cuantice pentru a spori proprietățile de absorbție lumina lor arata promisiune pentru proiectarea de celule solare mai bune și fotodetectori

Posted: Apr 08, 2016

Quantum dots enhance light-to-current conversion in layered metal dichalcogenide semiconductors

(Nanowerk News) Harnessing the power of the sun and creating light-harvesting or light-sensing devices requires a material that both absorbs light efficiently and converts the energy to highly mobile electrical current. Finding the ideal mix of properties in a single material is a challenge, so scientists have been experimenting with ways to combine different materials to create „hybrids” with enhanced features.
In two just-published papers, scientists from the U.S. Department of Energy’s Brookhaven National Laboratory, Stony Brook University, and the University of Nebraska describe one such approach that combines the excellent light-harvesting properties of quantum dots with the tunable electrical conductivity of a layered tin disulfide semiconductor. The hybrid material exhibited enhanced light-harvesting properties through the absorption of light by the quantum dots and their energy transfer to tin disulfide, both in laboratory tests and when incorporated into electronic devices. The research paves the way for using these materials in optoelectronic applications such as energy-harvesting photovoltaics, light sensors, and light emitting diodes (LEDs).
Quantum Dots
Single nanocrystal spectroscopy identifies the interaction between zero-dimensional CdSe/ZnS nano crystals (quantum dots) and two-dimensional layered tin disulfide as a non-radiative energy transfer, whose strength increases with increasing number of tin disulfide layers. Such hybrid materials could be used in optoelectronic devices such as photovoltaic solar cells, light sensors, and LEDs. (click on image to enlarge)
According to Mircea Cotlet, the physical chemist who led this work at Brookhaven Lab’s Center for Functional Nanomaterials, a DOE Office of Science User Facility, „Two-dimensional metal dichalcogenides like tin disulfide have some promising properties for solar energy conversion and photodetector applications, including a high surface-to-volume aspect ratio. But no semiconducting material has it all. These materials are very thin and they are poor light absorbers. So we were trying to mix them with other nanomaterials like light-absorbing quantum dots to improve their performance through energy transfer.”
One paper, just published in the journal ACS Nano („Nonradiative Energy Transfer from Individual CdSe/ZnS Quantum Dots to Single-Layer and Few-Layer Tin Disulfide”), describes a fundamental study of the hybrid quantum dot/tin disulfide material by itself. The work analyzes how light excites the quantum dots (made of a cadmium selenide core surrounded by a zinc sulfide shell), which then transfer the absorbed energy to layers of nearby tin disulfide.
„We have come up with an interesting approach to discriminate energy transfer from charge transfer, two common types of interactions promoted by light in such hybrids,” said Prahlad Routh, a graduate student from Stony Brook University working with Cotlet and co-first author of the ACS Nano paper. „We do this using single nanocrystal spectroscopy to look at how individual quantum dots blink when interacting with sheet-like tin disulfide. This straightforward method can assess whether components in such semiconducting hybrids interact either by energy or by charge transfer.”
The researchers found that the rate for non-radiative energy transfer from individual quantum dots to tin disulfide increases with an increasing number of tin disulfide layers. But performance in laboratory tests isn’t enough to prove the merits of potential new materials. So the scientists incorporated the hybrid material into an electronic device, a photo-field-effect-transistor, a type of photon detector commonly used for light sensing applications.
As described in a paper published online March 24 in Applied Physics Letters („Hybrid quantum dot-tin disulfide field-effect transistors with improved photocurrent and spectral responsivity”), the hybrid material dramatically enhanced the performance of the photo-field-effect transistors—resulting in a photocurrent response (conversion of light to electric current) that was 500 percent better than transistors made with the tin disulfide material alone.
„This kind of energy transfer is a key process that enables photosynthesis in nature,” said Chang-Yong Nam, a materials scientist at Center for Functional Nanomaterials and co-corresponding author of the APL paper. „Researchers have been trying to emulate this principle in light-harvesting electrical devices, but it has been difficult particularly for new material systems such as the tin disulfide we studied. Our device demonstrates the performance benefits realized by using both energy transfer processes and new low-dimensional materials.”
Cotlet concludes, „The idea of ‘doping’ two-dimensional layered materials with quantum dots to enhance their light absorbing properties shows promise for designing better solar cells and photodetectors.”
Source: Brookhaven National Laboratory

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Un cip de graphene filtrează lumina pentru a intensifica comunicațiile(A graphene chip filters light to boost communications)

au dezvoltat un microcip folosind grafen care ar putea ajuta datele de comunicații fără fir de comunicații la o rată de zece ori mai mare decât este posibil în prezent.Ei au descoperit că grafenul poate filtra radiațiile în același mod ca și ochelarii polarizați

Graphene

Condor Elite Sector Sling Bag Covert Combat Urban / Tactic Pack Tactical Armor Plate Carrier(Condor Elite Sector Sling Bag Covert Urban Combat/Tactical Pack Tactical Armor Plate Carrier )

Construit cu tesatura Cordura de 500 de denumiri Mil-Spec, fir de nylon compozit de înaltă rezistență la tracțiune și panglică;Kicker-ul este acela din moment ce aspectul sectorului Sling Bag-ului permite ca punga să fie mutată foarte rapid în fața utilizatorului, astfel că blagul blochează pieptul / torsul purtătorului, punga se poate dubla, de asemenea, ca o armură tactică improvizată un purtător de plăci de felul într-un vârf, în cazul în care purtătorul se află sub foc

Condor

Metodele utilizate pentru crearea de textile ar putea de asemenea ajuta la fabricarea țesuturilor umane(Methods used to create textiles also could help manufacture human tissues)

Ingineria țesuturilor este un proces care folosește noi biomateriale însămânțate cu celule stem pentru a crește și înlocui țesuturile lipsă;Metblowing este o tehnică în timpul căreia sunt create materiale nonwore folosind un polimer topit pentru a crea fibre continue

Methods

Pachetul de siguranță Condor Elite Fail Safe-Pack / Lo-Pro / Covert Urban Assault Pack (Rucsac) cu capacitate de hidratare Combat / Tactil(Condor Elite Fail Safe Pack Lo-Pro/Lo-Vis Covert Urban Assault Pack(Backpack) with Combat /Tactil Hydration Capability)

a prezentat recent unul dintre cele mai tari cele care au aparut in cadrul show-ului SHOT Show 2016, ca parte a liniei de produse relativ noi Condor Elite
Primul lucru pe care Dunn i la explicat lui DR a fost motivul pentru care a fost dat pachetului Safe Fail Safe, datorită influenței moderne a designului pachetului de parașute,

Condor

Selector de volum mare, desorbator termic cu temperatură variabilă, opțiuni de ionizare, planar DMA(High Volume sampler, Variable temperature thermal desorber, Ionization options,Planar DMA)

SEADM oferă dezvoltatorilor de produse o gamă completă de module care acoperă diferitele etape ale analizei nanoparticulelor și vaporilor, de la eșantionare până la procesarea semnalelor, inclusiv renumitul analizor de mobilitate diferențială, DMA

SEADM1

Oțelul de rupere a înregistrării ar putea fi folosit pentru armura corpului, scuturile pentru sateliți ( Recording-breaking steel could be used for body armor, shields for satellites

O echipă de ingineri a dezvoltat și testat un tip de oțel cu o abilitate de a rezista unui impact fără a se deforma permanent. Noul aliaj de oțel ar putea fi utilizat într-o gamă largă de aplicații, de la burghiu, la armura de corp pentru soldați, la carcasele rezistente la meteori pentru sateliți.

Posted: Apr 05, 2016

Recording-breaking steel could be used for body armor, shields for satellites

(Nanowerk News) A team of engineers has developed and tested a type of steel with a record-breaking ability to withstand an impact without deforming permanently. The new steel alloy could be used in a wide range of applications, from drill bits, to body armor for soldiers, to meteor-resistant casings for satellites.
The material is an amorphous steel alloy, a promising subclass of steel alloys made of arrangements of atoms that deviate from steel’s classical crystal-like structure, where iron atoms occupy specific locations.
Crystallinity in Steel alloy
This is a transmission electron microscopy image of different levels of crystallinity in the amorphous alloy. (Image: Jacobs School of Engineering/UC San Diego)
Researchers are increasingly looking to amorphous steel as a source of new materials that are affordable to manufacture, incredibly hard, but at the same time, not brittle. The researchers believe their work on the steel alloy, named SAM2X5-630, is the first to investigate how amorphous steels respond to shock.
SAM2X5-630 has the highest recorded elastic limit for any steel alloy, according to the researchers–essentially the highest threshold at which the material can withstand an impact without deforming permanently. The alloy can withstand pressure and stress of up to 12.5 giga-Pascals or about 125,000 atmospheres without undergoing permanent deformations.
The researchers, from the University of California, San Diego, the University of Southern California and the California Institute of Technology, describe the material’s fabrication and testing in a recent issue of Nature Scientific Reports („Shock Wave Response of Iron-based In Situ Metallic Glass Matrix Composites”).
„Because these materials are designed to withstand extreme conditions, you can process them under extreme conditions successfully,” said Olivia Graeve, a professor of mechanical engineering at the Jacobs School of Engineering at UC San Diego, who led the design and fabrication effort. Veronica Eliasson, an assistant professor at USC, led the testing efforts.
To make the solid materials that comprise the alloy, Graeve and her team mixed metal powders in a graphite mold. The powders were then pressurized at 100 mega-Pascals, or 1000 atmospheres, and exposed to a powerful current of 10,000 Ampers at 1165°F (630°C) during a process called spark plasma sintering.
The spark plasma sintering technique allows for enormous time and energy savings, Graeve said. „You can produce materials that normally take hours in an industrial setting in just a few minutes,” she said.
The process created small crystalline regions that are only a few nanometers in size, with hints of structure, which researchers believe are key to the material’s ability to withstand stress. This finding is promising because it shows that the properties of these types of metallic glasses can be fine-tuned to overcome shortcomings such as brittleness, which have prevented them from becoming commercially applicable on a large scale, Eliasson said.
Researchers at USC tested how the alloy responds to shock without undergoing permanent deformations by hitting samples of the material with copper plates fired from a gas gun at 500 to 1300 meters per second. The material did deform on impact, but not permanently.
The Hugoniot Elastic Limit (the maximum shock a material can take without irreversibly deforming) of a 1.5-1.8 mm-thick piece of SAM2X5-630 was measured at 11.76 ± 1.26 giga-Pascals.
By comparison, stainless steel has an elastic limit of 0.2 giga-Pascals, while that of tungsten carbide (a high-strength ceramic used in military armor) is 4.5 giga-Pascals. This isn’t to say that SAM2X5-630 has the highest elastic limit of any material known; diamonds top out at a whopping 60 giga-Pascals– they’re just not practical for many real-world applications. „The fact that the new materials performed so well under shock loading was very encouraging and should lead to plenty of future research opportunities,” said Eliasson.
The primary focus of future research efforts on these alloys is increasing the weight of the materials to make them more resistant to impacts.
Source: University of California – San Diego

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