Impactul îmbrăcămintei anti-miros de nanosilver asupra mediului(The impact ofanti-odor nanosilver clothing on the environment)

Cercetătorii au testat cămășile comerciale atletice în care nanoparticulele de argint au fost încorporate într-unul din cele patru moduri diferite;Cercetătorii spun, de asemenea, că argintul rămas va curge în timp când hainele sunt aruncate în depozitele de deșeuri

The impact

Calculatoarele în hainele tale? O piatră de hotar pentru electronice portabile(Computers in your clothes? A milestone for wearable electronics)

cercetătorii de la Universitatea de Stat din Ohio au făcut următorul pas către proiectarea de textile funcționale – haine care adună, stochează sau transmit informații digitale. Cu o dezvoltare ulterioară, tehnologia ar putea duce la cămăși care funcționează ca antene pentru telefonul sau tableta dvs. inteligentă, haine de antrenament care monitorizează nivelul de fitness, echipamente sportive care monitorizează performanța sportivilor, un bandaj care îi spune medicului cât de bine este țesutul sub el vindecare – sau chiar un capac flexibil de material care sesizează activitatea în creier.

Posted: Apr 13, 2016
Computers in your clothes? A milestone for wearable electronics (Nanowerk News) Researchers who are working to develop wearable electronics have reached a milestone: They are able to embroider circuits into fabric with 0.1 mm precision—the perfect size to integrate electronic components such as sensors and computer memory devices into clothing.
With this advance, the Ohio State University researchers have taken the next step toward the design of functional textiles—clothes that gather, store, or transmit digital information. With further development, the technology could lead to shirts that act as antennas for your smart phone or tablet, workout clothes that monitor your fitness level, sports equipment that monitors athletes’ performance, a bandage that tells your doctor how well the tissue beneath it is healing—or even a flexible fabric cap that senses activity in the brain.

Researchers at The Ohio State University are developing embroidered antennas and circuits with 0.1 mm precision—the perfect size to integrate electronic components such as sensors and computer memory devices into clothing. (Photo: Jo McCulty, The Ohio State University)
That last item is one that John Volakis, director of the ElectroScience Laboratory at Ohio State, and research scientist Asimina Kiourti are investigating. The idea is to make brain implants, which are under development to treat conditions from epilepsy to addiction, more comfortable by eliminating the need for external wiring on the patient’s body.
“A revolution is happening in the textile industry,” said Volakis, who is also the Roy & Lois Chope Chair Professor of Electrical Engineering at Ohio State. “We believe that functional textiles are an enabling technology for communications and sensing—and one day even medical applications like imaging and health monitoring.”
Recently, he and Kiourti refined their patented fabrication method to create prototype wearables at a fraction of the cost and in half the time as they could only two years ago. With new patents pending, they published the new results in the journal IEEE Antennas and Wireless Propagation Letters („Fabrication of Textile Antennas and Circuits With 0.1 mm Precision”).
In Volakis’ lab, the functional textiles, also called “e-textiles,” are created in part on a typical tabletop sewing machine—the kind that fabric artisans and hobbyists might have at home. Like other modern sewing machines, it embroiders thread into fabric automatically based on a pattern loaded via a computer file. The researchers substitute the thread with fine silver metal wires that, once embroidered, feel the same as traditional thread to the touch.
“We started with a technology that is very well known—machine embroidery—and we asked, how can we functionalize embroidered shapes? How do we make them transmit signals at useful frequencies, like for cell phones or health sensors?” Volakis said. “Now, for the first time, we’ve achieved the accuracy of printed metal circuit boards, so our new goal is to take advantage of the precision to incorporate receivers and other electronic components.”
The shape of the embroidery determines the frequency of operation of the antenna or circuit, explained Kiourti.
The shape of one broadband antenna, for instance, consists of more than half a dozen interlocking geometric shapes, each a little bigger than a fingernail, that form an intricate circle a few inches across. Each piece of the circle transmits energy at a different frequency, so that they cover a broad spectrum of energies when working together—hence the “broadband” capability of the antenna for cell phone and internet access.
“Shape determines function,” she said. “And you never really know what shape you will need from one application to the next. So we wanted to have a technology that could embroider any shape for any application.”
The researchers’ initial goal, Kiourti added, was just to increase the precision of the embroidery as much as possible, which necessitated working with fine silver wire. But that created a problem, in that fine wires couldn’t provide as much surface conductivity as thick wires. So they had to find a way to work the fine thread into embroidery densities and shapes that would boost the surface conductivity and, thus, the antenna/sensor performance.
Previously, the researchers had used silver-coated polymer thread with a 0.5-mm diameter, each thread made up of 600 even finer filaments twisted together. The new threads have a 0.1-mm diameter, made with only seven filaments. Each filament is copper at the center, enameled with pure silver.
They purchase the wire by the spool at a cost of 3 cents per foot; Kiourti estimated that embroidering a single broadband antenna like the one mentioned above consumes about 10 feet of thread, for a material cost of around 30 cents per antenna. That’s 24 times less expensive than when Volakis and Kiourti created similar antennas in 2014.
In part, the cost savings comes from using less thread per embroidery. The researchers previously had to stack the thicker thread in two layers, one on top of the other, to make the antenna carry a strong enough electrical signal. But by refining the technique that she and Volakis developed, Kiourti was able to create the new, high-precision antennas in only one embroidered layer of the finer thread. So now the process takes half the time: only about 15 minutes for the broadband antenna mentioned above.
She’s also incorporated some techniques common to microelectronics manufacturing to add parts to embroidered antennas and circuits.
One prototype antenna looks like a spiral and can be embroidered into clothing to improve cell phone signal reception. Another prototype, a stretchable antenna with an integrated RFID (radio-frequency identification) chip embedded in rubber, takes the applications for the technology beyond clothing. (The latter object was part of a study done for a tire manufacturer.)
Yet another circuit resembles the Ohio State Block “O” logo, with non-conductive scarlet and gray thread embroidered among the silver wires “to demonstrate that e-textiles can be both decorative and functional,” Kiourti said.
They may be decorative, but the embroidered antennas and circuits actually work. Tests showed that an embroidered spiral antenna measuring approximately six inches across transmitted signals at frequencies of 1 to 5 GHz with near-perfect efficiency. The performance suggests that the spiral would be well-suited to broadband internet and cellular communication.
In other words, the shirt on your back could help boost the reception of the smart phone or tablet that you’re holding – or send signals to your devices with health or athletic performance data.

Source: Ohio State University

Noile nanoparticule luminoase transparente asigură protecție la temperaturi ridicate împotriva contrafacerii(New transparent luminous nanoparticles provide high temperature stable protection against counterfeiting)

au dezvoltat particule luminoase care pot rezista la temperaturi ridicate;Utilizând pigmenți luminoși din oxid de ytriu sau oxid de gadoliniu, desenele tipărite sunt create în alb sau transparent, care strălucesc roșu portocaliu în lumină UV sau raze

New transparent

Utilizarea de nanotuburi pentru a crea fotoni singuri pentru comunicarea cuantică(Using nanotubes to create single photons for quantum communication)

cercetatorii au demonstrat ca noul material , realizat din tuburi de carbon mici, emite fotonii doriti la temperatura camerei

Using

Utilizarea nanotuburilor pentru a crea fotoni singulari pentru comunicarea cuantică(Using nanotubes to create single photons for quantum communication)

Cercetatorii au demonstrat un material nou, realizat din tuburi mici de carbon, care emite fotonii doriti la temperatura camerei.
Ascultarea electronică ar putea fi împiedicată prin codarea biților de informații în proprietățile sau stările mecanice cuantice ale fotonilor singuri. Fotoanele singulare emise de nanotuburi de carbon modificate sau dopate cu oxigen sunt deosebit de atractive pentru realizarea acestei tehnologii cuantice a informației.
Generarea de fotoni unici necesită un sistem izolat, mecanic cuantic, cu două nivele, care poate emite un singur foton într-un singur ciclu de emisie-excitație. În timp ce materialele nanometrice artificiale (cum ar fi punctele cuantice și centrele vacante în diamante) au fost explorate pentru generarea unui singur foton, nici unul nu a apărut ca un candidat ideal care să îndeplinească toate cerințele tehnologice.Dincolo de punerea în aplicare a acestei noi metode în tehnologiile de comunicare cuantică, sursele fotonice bazate pe nanotuburi ar putea permite alte tehnologii cuantice transformante, inclusiv măsurători de absorbție ultra-sensibile, imagini sub-difracție și computerizare liniară cuantică.

Posted: Apr 12, 2016
Using nanotubes to create single photons for quantum communication (Nanowerk News) Critical information, ranging from credit card numbers to national security data, is sent in streams of light, or laser pulses. However, the data transmitted in this manner can be stolen by splitting out a few photons (packets of light) from the laser pulse. Such eavesdropping could be prevented by encoding the data into single photons. But that requires generating single photons. Researchers demonstrated a new material, made from tiny carbon tubes, that emits the desired photons at room temperature.
Digital eavesdropping could be prevented by encoding bits of information in the properties, or quantum mechanical states, of single photons. Single photons emitted by carbon nanotubes altered, or doped with oxygen, are especially attractive for realizing this quantum information technology.
Single photon generation requires an isolated, quantum mechanical, two-level system that can emit only one photon in one excitation-emission cycle. While artificial nanoscale materials (such as quantum dots and vacancy centers in diamonds) have been explored for single photon generation, none have emerged as the ideal candidate that meets all of the technological requirements.
These requirements include the ability to generate single photons in the 1.3 to 1.5 µm fiber optic telecommunication wavelength range at room temperature. Earlier studies revealed that carbon nanotubes were not suited for use in quantum communications because the tubes required extremely low temperatures and had strong photoluminescence fluctuations.

The deposition of a silicon dioxide layer (yellow layer) on a carbon nanotube (gray spheres) introduces solitary oxygen dopants (red spheres). A single photon (red and white star) is emitted when a dopant is excited by a laser pulse (green arrow). (Image courtesy of the Center for Integrated Nanotechnologies)
In contrast to these earlier findings, researchers led by Han Htoon and Stephen Doorn of the Center for Integrated Nanotechnologies showed that oxygen doping of carbon nanotubes can lead to fluctuation-free photoluminescence emission in the telecommunication wavelength range (Nature Nanotechnology, „Room-temperature single-photon generation from solitary dopants of carbon nanotubes”).
Experiments measuring the time-distribution of two successive photon emission events also unambiguously demonstrated single photon emission at room temperature. Furthermore, because oxygen doping is achieved through a simple deposition of a silicon dioxide layer, these doped carbon nanotubes are fully compatible with silicon microfabrication technology and can be fabricated into electrically driven single photon sources.
In addition, the silicon dioxide layer encapsulating the nanotubes allows for their easy integration into electronic and photonic integrated circuits.
Beyond the implementation of this new method into quantum communication technologies, nanotube-based single photon sources could enable other transformative quantum technologies, including ultra-sensitive absorption measurements, sub-diffraction imaging, and linear quantum computing.

Source: Department of Energy, Office of Science

Ștergerea modului de aplicare a suprafețelor superhidrofobe în lumea reală(Clearing the way for real-world applications of superhydrophobic surfaces )

ar progresa în mod semnificativ dezvoltarea materialelor superhidrofobe și transferul lor către produse comerciale, de exemplu în aplicații cu autocurățare și anti-înghețare. ) Testul de abraziune liniar. (B) Pe o suprafață superhidrofobică, o picătură de apă se rotește cu frecare redusă, cauzată de captarea unui strat subțire de aer între rugozitatea suprafeței. (C) Deteriorarea rugozității suprafeței duce la fixarea picăturilor

Posted: Apr 09, 2016
Clearing the way for real-world applications of superhydrophobic surfaces (Nanowerk News) In their perspective article in the journal Science („Moving superhydrophobic surfaces toward real-world applications”), researchers from Aalto University call for consistent and standardized testing of superhydrophobic, i.e. extremely water-repellent, materials. Agreeing on a unified testing method is needed to allow community-wide comparison between published results. This would significantly progress development of superhydrophobic materials and their transfer to commercial products in, for instance, self-cleaning and anti-icing applications.

(A) Linear abrasion test. (B) On a superhydrophobic surface a water droplet rolls with low friction, as caused by trapping of a thin air layer between the surface roughness. (C) Damaging the surface roughness leads to droplet pinning. (Image: Juan Li, Aalto University)
Currently, research groups around the world use many different kinds of tests to evaluate the durability and wear of superhydrophobic materials. For example, researchers have used linear abrasion, circular abrasion, sandblasting and water jets in testing the surfaces. However, the results obtained through different methods are not comparable, which makes it hard to find the best materials for applications.
‘We therefore propose that researchers should begin using a standardised method when testing the wear and durability of extremely water-repellent materials. We find that linear abrasion of the surface, for example with sandpaper, would be the best general method. It is important to specify the applied pressure, the abrasion distance and the abradant material to make sure the result is reproducible’, explains Professor Robin Ras.
Benefits of the proposed method include, among other things, the easy availability of the testing materials and the simple test setup.
‘Nevertheless, the wear test alone is not sufficient to determine the robustness of the superhydrophobic surface. The second step is to perform tests with water droplets to measure the water-repelling properties of the surface after wear’, clarifies Tuukka Verho, who is currently preparing his doctoral dissertation.
The superhydrophobicity of a surface is often measured based on the shape of a water droplet on the surface, i.e. how completely the droplet beads up in the surface. However, according to the authors, this so-called static contact angle does not provide enough information about the effects of wear, as water often forms almost spherical droplets even on a damaged surface, but no longer easily slides off the surface. Therefore, the authors encourage to always measure droplet mobility, for example using an inclination test.
The Aalto University researchers wish that their perspective article initiates in the research community a discussion on the evaluation of superhydrophobic surfaces. Even though they propose linear abrasion as a primary test for all superhydrophobic materials, additional application-specific tests may be needed, for instance, to assess the laundering durability of textiles or the weather-durability of outdoor materials.

Source: Aalto University

Servirea nanopachetelor MoO3 proaspete, curate și monostrat subțiri ( Serving up fresh, clean, and monolayer-thin MoO3 nanosheets )

Molibden (α-MoO 3 ) conține , de asemenea , astfel de straturi 2D, care sunt legate între ele prin slabe forțe van der Waals care cauzeaza o molecula care urmeaza sa fie atras sau impins departe de o altă moleculă.
Structura unică stratată face ca α-MoO 3 să fie un material atrăgător pentru utilizarea în bateriile litiu-ion și dispozitivele electrochromice, cum ar fi ferestrele „inteligente” care controlează absorbția luminii solare în clădiri și oglinzile retrovizoare auto-dim care protejează șoferii de lumini de mare viteză .

Posted: Apr 09, 2016
Serving up fresh, clean, and monolayer-thin MoO3 nanosheets (Nanowerk News) The 2010 Nobel Prize in physics was awarded to Manchester scientists Andre Geim and Konstantin Novoselov for their pioneering work with graphene, a 1-atom-thick, two-dimensional (2D) network of carbon that may revolutionize computing and electronics. Molybdenum trioxide (α-MoO3) also contains such 2D layers, which are linked together through weak van der Waals forces that cause a molecule to become attracted or pushed away from another molecule.
The unique layered-structure makes α-MoO3 an attractive material for use in lithium ion batteries and electrochromic devices, such as „smart” windows that control solar light absorption in buildings and auto-dim rearview mirrors that protect drivers from high-beam lights.
3 molecular fragments from the surface of a single monolayer during film growth” border=”0″ align=”middle”>
Schematic representation of the re-evaporation of α-MoO3 molecular fragments from the surface of a single monolayer during film growth. At the optimum substrate temperature, only one monolayer “sticks” to the substrate because of strong interaction between the two; all other monolayers desorb because of weak van der Waals interaction with the first layer.
Results
Materials scientists at Pacific Northwest National Laboratory have overcome a set of challenges in synthesis and isolation of ultra-thin α-MoO3 layers. They developed a reproducible method for growing α-MoO3 sheets down to a monolayer in thickness. They used a thin-film deposition technique, molecular beam epitaxy (MBE), to synthesize α-MoO3. A stable oxide substrate provided the needed template (Nanoscale, „Iso-oriented Monolayer α-MoO3(010) Films Epitaxially Grown on SrTiO3(001)”).
The secret to growing monolayer-thin α-MoO3 is multi-faceted. The scientists’ success hinged on the right substrate that provides lateral confinement to the α-MoO3, and the carefully identified growth temperature, which allows α-MoO3 seeds to evolve, grow, but stop right at the monolayer thickness. Their results, which can greatly advance our current understanding on the material’s physical and chemical properties, appear in the scientific journal Nanoscale.
Why It Matters
Besides electrochemical and catalytic applications, ultra-thin α-MoO3 has also demonstrated its potential use in thin-film pseudocapacitors, light-emitting diodes, plasmon resonance generators, and biosensors. It is critical to be able to synthesis and isolate such 2D materials in a contamination-free environment (ultra-high vacuum) to better understand their intrinsic properties. The PNNL science team was able to meet these high standards by combining instrumentation and capabilities in the Environmental Molecular Sciences Laboratory (EMSL), a DOE national user facility.
Methods
„To grow the layers, we evaporate high-purity MoO3 powders held in a ceramic cup in ultra-high vacuum and put a substrate in front to collect the molecules,” said Dr. Yingge Du, lead scientist on the project. The evaporated MoO3 molecules will condense and form a well-ordered thin film on the heated substrate.
Du likens the substrate to a Lego© base plate. „If you throw atoms together randomly, they will stick together like a pile of Lego pieces in a random, messy way. But with a good base template, you can position the Legos in an ordered fashion, and make nice structures.”
And, MoO3 film growth is temperature sensitive. „At lower substrate temperatures, the material will grow as amorphous layers and become thicker and thicker. At higher temperatures, unwanted phases and structures start to evolve,” Du said. „We were extremely delighted that a very narrow temperature window was found for us to grow this material as a single monolayer.”
The correct temperature-in this case, 450°C-allows a crystalline layer to form on the substrate, stabilized by interfacial chemistry. However, the growth of subsequent MoO3 layers is suppressed by material re-evaporation from the substrate. The high substrate temperature and weak van der Waals bonding between adjacent MoO3 layers allow a self-limiting growth process, which provides a highly reliable technique for MoO3 to form and stay as a monolayer.
„Using traditional methods, these nanomaterials are hard to grow or isolate. The trick is to find the optimal temperature that not only provides enough thermal energy to start the crystal structure, but also is high enough to de-adsorb additional layers,” said Du.
What’s Next?
The research also paves the way to creating phase-pure, thicker films by lowering the growth temperature once the monolayer template is formed. The team plans to further investigate the electronic, transport, and catalytic properties of these films using various in situ spectroscopy and microscopy techniques at EMSL.

Source: Pacific Northwest National Laboratory

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

O piele inteligentă auto-alimentată, ca cea recent dezvoltată de o echipă de cercetători chinezi, rezolvă fundamental această problemă. În această lucrare, oamenii de știință combină efectul triboelectric și inducția electrostatică plană și o aplică într-o structură subtilă pentru prima dată pentru a crea o piele inteligentă analogică inteligentă.

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 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 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 Berger – 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

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

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).

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

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