februarie 2018 – Pagina 2

Senzori pentru senzorii de cameră: Un material, multe aplicații(Nanomushroom sensors: One material, many applications)

Diapozitivul este fabricat dintr-un material „nanoplasmonic” – suprafața sa este acoperită în milioane de nanostructuri de aur, fiecare cu doar câteva miliarde de metri pătrați. Materialele plasmonice absorb și dispersează lumina în moduri interesante, oferindu-le proprietăți senzoriale unice. Materialele nanoplasmonice au atras atenția biologilor, chimistilor, fizicienilor și oamenilor de știință cu posibilități de utilizare într-o gamă diversă de domenii, precum biosensibilizarea, stocarea datelor, generarea de lumină și celulele solare.materialele nanoplasmonice pot fi integrate chiar și în tehnologii emergente, cum ar fi sistemele fără fir în dispozitivele microfluidice, permițând utilizatorilor să ia lecturi de la distanță și astfel să reducă la minimum riscul de contaminare.dezvoltat un nou material plasmonic pentru monitorizarea calității produselor alimentare în timpul procesului de fabricație.

Posted: Feb 23, 2018
Nanomushroom sensors: One material, many applications (Nanowerk News) A small rectangle of pink glass, about the size of a postage stamp, sits on Professor Amy Shen’s desk. Despite its outwardly modest appearance, this little glass slide has the potential to revolutionize a wide range of processes, from monitoring food quality to diagnosing diseases.
The slide is made of a ‘nanoplasmonic’ material – its surface is coated in millions of gold nanostructures, each just a few billionths of a square meter in size. Plasmonic materials absorb and scatter light in interesting ways, giving them unique sensing properties. Nanoplasmonic materials have attracted the attention of biologists, chemists, physicists and material scientists, with possible uses in a diverse array of fields, such as biosensing, data storage, light generation and solar cells.

Schematic illustration of cells (blue mountain-like shapes) on top of nanoscale mushroom-like structures with silicone dioxide stems and gold caps, which have the potential to detect cell proliferation in real-time. (Image: OIST)
In several recent papers, Prof. Shen and colleagues at the Micro/Bio/Nanofluidics Unit at the Okinawa Institute of Science and Technology (OIST), described their creation of a new biosensing material that can be used to monitor processes in living cells.
„One of the major goals of nanoplasmonics is to search for better ways to monitor processes in living cells in real time,” says Prof. Shen. Capturing such information can reveal clues about cell behavior, but creating nanomaterials on which cells can survive for long periods of time yet don’t interfere with the cellular processes being measured is a challenge, she explains.
Counting Dividing Cells
One of the team’s new biosensors is made from a nanoplasmonic material that is able to accommodate a large number of cells on a single substrate and to monitor cell proliferation, a fundamental process involving cell growth and division, in real time. Seeing this process in action can reveal important insights into the health and functions of cells and tissues.
Researchers in OIST’s Micro/Bio/Nanofluidics Unit described the sensor in a study recently published in the journal Advanced Biosystems („Large-Scale Nanophotonic Structures for Long-Term Monitoring of Cell Proliferation”).

Using their innovative printing technique, the Micro/Bio/Nanofluidics Unit at OIST has developed a nanoplasmonic material containing millions of mushroom-like structures covered with a uniform layer of biomolecules. (Image: OIST)
The most attractive feature of the material is that it allows cells to survive over long time periods. „Usually, when you put live cells on a nanomaterial, that material is toxic and it kills the cells,” says Dr. Nikhil Bhalla, a postdoctoral researcher at OIST and first author of the paper. „However, using our material, cells survived for over seven days.” The nanoplasmonic material is also highly sensitive: It can detect an increase in cells as small as 16 in 1000 cells.
The material looks just like an ordinary pieces of glass. However, the surface is coated in tiny nanoplasmonic mushroom-like structures, known as nanomushrooms, with stems of silicon dioxide and caps of gold. Together, these form a biosensor capable of detecting interactions at the molecular level.
The biosensor works by using the nanomushroom caps as optical antennae. When white light passes through the nanoplasmonic slide, the nanomushrooms absorb and scatter some of the light, changing its properties. The absorbance and scattering of light is determined by the size, shape and material of the nanomaterial and, more importantly, it is also affected by any medium in close proximity to the nanomushroom, such as cells that have been placed on the slide. By measuring how the light has changed once it emerges through the other side of the slide, the researchers can detect and monitor processes occurring on the sensor surface, such as cell division.
„Normally, you have to add labels, such as dyes or molecules, to cells, to be able to count dividing cells,” says Dr. Bhalla. „However, with our method, the nanomushrooms can sense them directly.”
Scaling Up
This work builds on a new method, developed by scientists at the Micro/Bio/Nanofluidics Unit at OIST, for fabricating nanomushroom biosensors. The technique was published in the journal ACS Applied Materials and Interfaces in December 2017 („Plasma-Assisted Large-Scale Nanoassembly of Metal–Insulator Bioplasmonic Mushrooms”).
Producing large-scale nanoplasmonic materials is challenging because it is difficult to ensure uniformity across the entire material surface. For this reason, biosensors for routine clinical examinations, such as disease testing, are still lacking.
In response to this problem, the OIST researchers developed a novel printing technique to create large-scale nanomushroom biosensors. With their method, they were able to develop a material consisting of approximately one million mushroom-like structures on a 2.5cm by 7.5cm silicon dioxide substrate.

Nanomushroom biosensors can be used to count dividing cells and detect biomolecules. (Image: OIST)
„Our technique is like taking a stamp, covering it with ink made from biological molecules, and printing onto the nanoplasmonic slide,” says Shivani Sathish, a PhD student at OIST and co-author of the paper. The biological molecules increase the sensitivity of the material, meaning it can sense extremely low concentrations of substances, such as antibodies, and thus potentially detect diseases in their earliest stages.
„Using our method, it is possible to create a highly sensitive biosensor that can detect even single molecules,” says Dr. Bhalla, first author of the paper.
Plasmonic and nanoplasmonic sensors offer important tools for many fields, from electronics to food production to medicine. For example, in December 2017, second year Ph.D student Ainash Garifullina from the Unit developed a new plasmonic material for monitoring the quality of food products during the manufacturing process. The results were published in the journal Analytical Methods („Probing specific gravity in real-time with graphene oxide plasmonics „).
Prof. Shen and her unit say that, in the future, nanoplasmonic materials may even be integrated with emerging technologies, such as wireless systems in microfluidic devices, allowing users to take readings remotely and thereby minimizing the risk of contamination.

Source: By Sophie Protheroe, Okinawa Institute of Science and Technology (OIST) Graduate University

Cercetatorii combina metalens cu un muschi artificial (w / video)(

Inspirata de ochiul uman, cercetatorii de la Harvard John A. Paulson Scoala de Inginerie si Stiinte Aplicate (SEAS) au dezvoltat o metalens adaptive, care este in esenta un ecran plat, controlat electronic. Metalena adaptivă controlează simultan trei dintre cei mai importanți contribuitori la imagini neclare: focalizare, astigmatism și schimbare de imagine.Toate sistemele optice cu componente multiple – de la camere la microscoape și telescoape – au o ușoară aliniere sau solicitări mecanice asupra componentelor lor, în funcție de modul în care au fost construite și de mediul lor actual, care vor determina întotdeauna mici cantități de astigmatism și alte aberații ar putea fi corectat de un element optic adaptiv „, a spus ea. „Deoarece metalendurile adaptive sunt plane, puteți corecta aceste aberații și puteți integra diferite capabilități optice într-un singur plan de control”.
În continuare, cercetătorii urmăresc să îmbunătățească în continuare funcționalitatea obiectivului și să reducă tensiunea necesară pentru controlul acestuia.

Posted: Feb 23, 2018
Researchers combine metalens with an artificial muscle (w/video) (Nanowerk News) Inspired by the human eye, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed an adaptive metalens, that is essentially a flat, electronically controlled artificial eye. The adaptive metalens simultaneously controls for three of the major contributors to blurry images: focus, astigmatism, and image shift.
The research is published in Science Advances („Adaptive metalenses with simultaneous electrical control of focal length, astigmatism, and shift”).

The adaptive metalens focuses light rays onto an image sensor. An electrical signal controls the shape of the metalens to produce the desired optical wavefronts (shown in red), resulting in better images. In the future, adaptive metalenses will be built into imaging systems, such as cell phone cameras and microscope, enabling flat, compact autofocus as well as the capability for simultaneously correcting optical aberrations and performing optical image stabilization, all in a single plane of control. (Image: Capasso Lab/Harvard SEAS)
„This research combines breakthroughs in artificial muscle technology with metalens technology to create a tunable metalens that can change its focus in real time, just like the human eye,” said Alan She, a graduate student at SEAS and first author of the paper. „We go one step further to build the capability of dynamically correcting for aberrations such as astigmatism and image shift, which the human eye cannot naturally do.”
„This demonstrates the feasibility of embedded optical zoom and autofocus for a wide range of applications including cell phone cameras, eyeglasses and virtual and augmented reality hardware,” said Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS and senior author of the paper. „It also shows the possibility of future optical microscopes, which operate fully electronically and can correct many aberrations simultaneously.”
The Harvard Office of Technology Development has protected the intellectual property relating to this project and is exploring commercialization opportunities.
To build the artificial eye, the researchers first needed to scale-up the metalens.
Prior metalenses were about the size of a single piece of glitter. They focus light and eliminate spherical aberrations through a dense pattern of nanostructures, each smaller than a wavelength of light.
„Because the nanostructures are so small, the density of information in each lens is incredibly high,” said She. „If you go from a 100 micron-sized lens to a centimeter sized lens, you will have increased the information required to describe the lens by ten thousand. Whenever we tried to scale-up the lens, the file size of the design alone would balloon up to gigabytes or even terabytes.”

Photo of the metalens (made of silicon) mounted on a transparent, stretchy polymer film, without any electrodes. The colorful iridescence is produced by the large number of nanostructures within the metalens. (Image courtesy of the Capasso Lab/Harvard SEAS)
To solve this problem, the researchers developed a new algorithm to shrink the file size to make the metalens compatible with the technology currently used to fabricate integrated circuits. In a paper recently published in Optics Express, the researchers demonstrated the design and fabrication of metalenses up to centimeters or more in diameter.
„This research provides the possibility of unifying two industries: semiconductor manufacturing and lens-making, whereby the same technology used to make computer chips will be used to make metasurface-based optical components, such as lenses,” said Capasso.
Next, the researchers needed to adhere the large metalens to an artificial muscle without compromising its ability to focus light. In the human eye, the lens is surrounded by ciliary muscle, which stretches or compresses the lens, changing its shape to adjust its focal length. Capasso and his team collaborated with David Clarke, Extended Tarr Family Professor of Materials at SEAS and a pioneer in the field of engineering applications of dielectric elastomer actuators, also known as artificial muscles.
The researchers chose a thin, transparent dielectic elastomer with low loss – meaning light travels through the material with little scattering – to attach to the lens. To do so, they needed to developed a platform to transfer and adhere the lens to the soft surface.
„Elastomers are so different in almost every way from semiconductors that the challenge has been how to marry their attributes to create a novel multi-functional device and, especially how to devise a manufacturing route,” said Clarke. „As someone who worked on one of the first scanning electron microscopes (SEMs) in the mid 1960’s, it is exhilarating to be a part of creating an optical microscope with the capabilities of an SEM, such as real-time aberration control.”
The elastomer is controlled by applying voltage. As it stretches, the position of nanopillars on the surface of the lens shift. The metalens can be tuned by controlling both the position of the pillars in relation to their neighbors and the total displacement of the structures. The researchers also demonstrated that the lens can simultaneously focus, control aberrations caused by astigmatisms, as well as perform image shift.
Together, the lens and muscle are only 30 microns thick.

„All optical systems with multiple components – from cameras to microscopes and telescopes – have slight misalignments or mechanical stresses on their components, depending on the way they were built and their current environment, that will always cause small amounts of astigmatism and other aberrations, which could be corrected by an adaptive optical element,” said She. „Because the adaptive metalens is flat, you can correct those aberrations and integrate different optical capabilities onto a single plane of control.”
Next, the researchers aim to further improve the functionality of the lens and decrease the voltage required to control it.

Source: By Leah Burrows, Harvard John A. Paulson School of Engineering and Applied Sciences

Cercetătorii transformă lumina cu susul în jos(Researchers turn light upside down)

Acum, cercetatorii au dezvoltat o astfel de metasurface pentru lumina infrarosie. Se bazează pe nitrura de bor, un material 2D de tip grafen și a fost selectat datorită capacității sale de a manipula lumina infraroșie pe scări extrem de mici, care ar putea fi aplicate pentru dezvoltarea unor senzori chimici miniaturizați sau pentru gestionarea căldurii în dispozitivele optoelectronice nanometrice

Posted: Feb 22, 2018
Researchers turn light upside down (Nanowerk News) Optical waves propagating away from a point source typically exhibit circular (convex) wavefronts. „Like waves on a water surface when a stone is dropped”, explains Peining Li, EU Marie Sklodowska-Curie fellow at nanoGUNE and first author of the paper. The reason of this circular propagation is that the medium through which light travels is typically homogenous and isotropic i.e. uniform in all directions.
Scientists had already theoretically predicted that specifically structured surfaces can turn the wavefronts of light upside down when it propagates along them.
„On such surfaces, called hyberbolic metasurfaces, the waves emitted from a point source propagate only in certain directions and with open (concave) wavefronts”, explains Javier Alfaro, PhD student at nanoGUNE and co-author of the paper. These unusual waves are called hyperbolic surface polaritons.
Because they propagate only in certain directions, and with wavelengths that are much smaller than that of light in free space or standard waveguides, they could help to miniaturize optical devices for sensing and signal processing.
Now, the researchers developed such a metasurface for infrared light. It is based on boron nitride, a graphene-like 2D material, and was selected because of its capability to manipulate infrared light on extremely small length scales, which could be applied for the development of miniaturized chemical sensors or for heat management in nanoscale optoelectronic devices. On the other hand, the researchers succeeded to directly observe the concave wavefronts with a special optical microscope, which have been elusive so far (Science, „Infrared hyperbolic metasurface based on nanostructured van der Waals materials”).

This is an illustration of waves propagating away from a point-like source. Left: Regular wave propagation. Right: Wave propagation on a hyperbolic metasurface. (Image: P. Li, CIC nanoGUNE)
Hyperbolic metasurfaces are challenging to fabricate because an extremely precise structuring on the nanometer scale is required. Irene Dolado, PhD student at nanoGUNE, and Saül Vélez, former postdoctoral researcher at nanoGUNE (now at ETH Zürich) mastered this challenge by electron beam lithography and etching of thin flakes of high-quality boron nitride provided by Kansas State University.
„After several optimization steps, we achieved the required precision and obtained grating structures with gap sizes as small as 25 nm”, Dolado says. „The same fabrication methods can also be applied to other materials, which could pave the way to realize artificial metasurface structures with custom-made optical properties”, adds Saül Vélez.
To see how the waves propagate along the metasurface, the researchers used a state-of the-art infrared nanoimaging technique that was pioneered by the nanoptics group at nanoGUNE. They first placed an infrared gold nanorod onto the metasurface.
„It plays the role of a stone dropped into water”, says Peining Li. The nanorod concentrates incident infrared light into a tiny spot, which launches waves that then propagate along the metasurface. With the help of a so-called scattering-type scanning near-field microscope (s-SNOM) the researchers imaged the waves.
„It was amazing to see the images. They indeed showed the concave curvature of the wavefronts that were propagating away form the gold nanorod, exactly as predicted by theory”, says Rainer Hillenbrand, Ikerbasque Professor at nanoGUNE, who led the work.
The results promise nanostructured 2D materials to become a novel platform for hyberbolic metasurface devices and circuits, and further demonstrate how near-field microscopy can be applied to unveil exotic optical phenomena in anisotropic materials and for verifying new metasurface design principles.

Source: nanoGUNE

Betonul infuzat cu nanocristale din lemn este mai puternic(Concrete infused with wood nanocrystals is stronger)

Cercetatorii spun ca munca in scaling la beton si pregatirea pentru pod in California este un parteneriat intre Purdue, Universitatea de Stat din Oregon, P3Nano si altii. P3Nano este un parteneriat public-privat conceput pentru a sprijini comercializarea nanomaterialelor celulozice. P3Nano a fost implicat activ în studiile la scară largă și este sponsorul proiectului de la Universitatea de Stat din Oregon pentru a demonstra aplicațiile la scară largă ale nanocristalelor de celuloză în poduri și plăci plate. Puntea exactă din California, unde se va utiliza betonul infuzat cu celuloză, nu a fost încă determinată.

Posted: Feb 22, 2018
Concrete infused with wood nanocrystals is stronger (Nanowerk News) Purdue University researchers studying whether concrete is made stronger by infusing it with microscopic-sized nanocrystals from wood are moving from the laboratory to the real world with a bridge that will be built in California this spring.
The researchers have been working with cellulose nanocrystals, byproducts generated by the paper, bioenergy, agriculture and pulp industries, to find the best mixture to strengthen concrete, the most common man-made material in the world.
“Simply getting out there where people can actually drive on it, I think, is a huge step because you can’t just say it’s a lab curiosity at that point. It has real-world implications,” said Jeffrey Youngblood, a Purdue professor of materials engineering.
Strengthening concrete could have other implications, such as making items made with concrete thinner and lighter while retaining the same strength with a potential side benefit of decreasing carbon dioxide released into the atmosphere. Cement plants account for an estimated 8 percent of global emissions of carbon dioxide, a main cause of climate change.
The catalyst for this potentially transformative change is a cellulose nanocrystal about 100 nanometers long and 5 nanometers wide, too small to be seen using an ordinary microscope. It can be seen only using an electron microscope. For perspective, a human hair is about 100,000 nanometers wide. Yet cellulose is the most common polymer in the world because it can be obtained from wood products, plants, bacteria and algae.

This transmission electron microscope shows cellulose nanocrystals, tiny structures derived from renewable sources that might be used to create a new class of biomaterials with many potential applications. The structures have been shown to increase strength of concrete. (Image: Purdue Life Sciences Microscopy Center)
The cellulose nanocrystals make the concrete stronger through a chemical reaction that increases the hydration of the cement particles, making the concrete stronger, the researchers say. “The strength of concrete scales with the degree of hydration. So the more hydrated it is, the stronger it is,” Youngblood said. “So you’d think if you add more water it would be stronger. The problem is, water adds pores that make it weaker. But cellulose nanocrystals enhance hydration with less water, making the concrete stronger.”
Pablo Zavattieri, a professor in the Lyles School of Civil Engineering, said the cellulose nanocrystals provide an avenue for the water to go where it is needed. Not all cement particles are hydrated when concrete is mixed, which hampers the strength and durability of the concrete.
“The good thing about cellulose nanocrystals is it kind of creates a rail for the water to go into a particle, Zavattieri said.
Jason Weiss, the Miles Lowell and Margaret Watt Edwards Distinguished Chair in Engineering at Oregon State University, who previously was a professor at Purdue, said the cellulose nanocrystals make concrete more efficient because less mass is needed to make something that is equally strong.
“So it can be more sustainable and more efficient,” he said.
Youngblood said another benefit is that the cellulose-infused concrete sets faster, which means less waiting for concrete to cure when using forms to make bridges or for oil drilling.
“Because every day that a crew is out there not pumping oil is a day losing money,” Youngblood said.

This photo shows cement samples embedded in epoxy ready for microscopy analysis. Purdue University researchers have been working to find the best ratio of mixing cellulose nanocrystals into cement to make it stronger.(Image: PurdueUniversity)
The researchers say the cost of using the cellulose nanocrystals may be offset by being able to use less cement, but the exact cost hasn’t been determined. They say how widely cellulose nanocrystals are used will be a factor. But even if only a small percentage of all the concrete produced used the cellulose nanocrystals, it would have a big impact just because concrete use is so ubiquitous.
The researchers say the work in scaling to concrete and preparing for the bridge in California is a partnership between Purdue, Oregon State University, P3Nano and others. P3Nano is a public-private partnership designed to support the commercialization of cellulosic nanomaterial. P3Nano has been actively involved in the full-scale trials and is the sponsor of the project at Oregon State University to demonstrate full-scale applications of cellulose nanocrystals in bridges and flat slabs. The exact bridge in California where the cellulose-infused concrete will be used has not yet been determined.
The Purdue researchers began looking into cellulose a decade ago in collaboration with Robert Moon, a researcher from the U.S. Forest Service Forest Products Laboratory, who was based at Purdue at the time. The Forest Service was looking for uses for diseased, damaged and small-diameter logs, which are plentiful in forests.
Youngblood, who works primarily with plastics, said the challenge initially was determining where the water-soluble cellulose nanocrystals could be used. The idea of using it in concrete came to him while digging a posthole and preparing concrete. That’s where the research began.
Youngblood said the researchers quickly found that the cellulose nanocrystals made the concrete stronger, but they didn’t know why.
“I walked down to the office of Jason Weiss and showed him the data and he said it shouldn’t work because the cellulose nanocrystals are too small. That’s when we realized we had something, because if something based on how things normally work, based on theories or whatever, shouldn’t work and it does, that’s when you usually have found something important,” Youngblood said. “That’s how it all started.”

Source: Purdue University

Amintește-te foarte repede(Remembering really fast)

În compozitele proiectate, conductivitatea electrică poate fi controlată atât de un câmp magnetic aplicat cât și de o temperatură. Activitatea echipei evidențiază o nouă abordare a controlului conductivității în aceste filme subțiri. Astfel de materiale ar putea revoluționa designul dispozitivelor de memorie.
Putem construi dispozitive de memorie noi pentru a face citirea și scrierea datelor la frecvențe terahertz astfel încât dispozitivele noastre personale să poată funcționa la o viteză mult mai mare?Cercetările sugerează promisiunea acestui sistem material pentru viitoarele componente optice și electronice terahertz, cum ar fi modulatorii magnetici.

Posted: Feb 22, 2018
Remembering really fast (Nanowerk News) Electronics could work faster if they could read and write data at terahertz frequency, rather than at a few gigahertz. Creating such devices would be eased with materials that can undergo a huge change in how easily they conducted electricity in response to a magnetic field at room temperature. Scientists believe thin films of perovskite oxides hold promise for such uses. However, such behavior has never been seen at these frequencies in these films.
Until now. Via terahertz pulses, scientists at Center for Integrated Nanotechnologies and the United Kingdom discovered colossal changes in electricity’s flow at the desired frequencies and temperature (Nano Letters, „Colossal Terahertz magnetoresistance at room temperature in epitaxial La0.7Sr0.3MnO3 nanocomposites and single-phase thin films”).

A graphic depicts the interactions of terahertz pulses (pink) with a vertically aligned nanocomposite. B is the magnetic field and ETHz is the THz electric field. The nanocomposite film includes vertical zinc oxide (ZnO) tiny pillars (red) embedded in lanthanum strontium manganite film matrix (yellow). (Image: Chris Sheehan, Center for Integrated Nanotechnologies, Los Alamos National Laboratory)
In the designer composites, electrical conductivity can be controlled by both an applied magnetic field and temperature. The team’s work highlights a new approach to control conductivity in these thin films. Such materials might revolutionize the design of memory devices.
Can we build novel memory devices to do data reading and writing at terahertz frequencies so that our personal devices can operate at a much higher speed?
A team of researchers from the Center for Integrated Nanotechnologies and universities in the United Kingdom found a colossal magnetoresistance at terahertz frequencies at room temperature in high-quality functional nanocomposites. The terahertz conductivity of nanocomposites can be controlled by both an applied magnetic field and temperature.
For example, in the presence of an external field (for example, 2 terahertz), the terahertz conductivity changes over two orders of magnitude.
These findings demonstrated a new approach of utilizing optic pulses at terahertz frequencies to probe magnetoresistance, which can revolutionize the design of future memory devices. Different from conventional colossal magnetoresistance observed at high magnetic fields and low temperatures, this newly developed colossal magnetoresistance at terahertz frequencies can be seen at room temperature and intermediate magnetic fields.
The team studied the underlying physical mechanisms with terahertz time-domain magnetospectroscopy. Researchers can use the results to guide the future development of novel functional thin films with better performance. The experiments show that colossal magnetoresistance at terahertz frequencies may be used in extremely small electronics and in terahertz optical components controlled by magnetic fields.
The research suggests the promise of this material system for future terahertz optical and electronic components, such as magnetically driven modulators.

Source: U.S. Department of Energy, Office of Science

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Filme adezive antimicrobiene inovatoare pentru reducerea riscului de infecție în spitale(Innovative antimicrobial adhesive films to reduce infection risk in hospitals)

Aceste filme de plastic antimicrobiene vor fi utilizate în spitale pentru a reduce riscul de infecție. În acest sens, obiectivul principal al FLEXPOL este acela ca materialul să fie utilizat pe suprafețe mari, cum ar fi pereții și podelele, precum și pe cele mai mici, cum ar fi mesele, paturile sau ușile, unde cresc tot mai multe bacterii. Din acest motiv, produsul va fi testat în medii medicale actuale, și anume la Spitalul Universitar Donostia, partener de proiect, pentru a evalua cât de eficiente, durabile și rezistente la infecții sunt aceste filme, precum și compatibilitatea acestora cu protocoalele de curățare și dezinfectare loc.

Posted: Feb 09, 2018
Innovative antimicrobial adhesive films to reduce infection risk in hospitals (Nanowerk News) In Europe each year, over 500,000 people get infected in hospitals, in unsterilised transit areas such as toilets, corridors or rooms. The University of Alicante Research Group in Polymer and Nanomaterial Analysis (NANOBIOPOL), together with research and industry staff from Italy, Spain, Portugal, the UK and Germany, is involved in the FLEXPOL project to make an antimicrobial adhesive film reducing infection risk in hospitals.
In hospitals, patients, visitors and staff are at high risk of fatal bacterial infections. FLEXPOL, funded by the European Commission, is intended to develop a pilot line for cost-effectively producing these transparent, antimicrobial, polypropylene-based films.
To that end, two factors are essential: nanostructures on the plastic surface and capsules containing a mixture of oils with antimicrobial properties. The surface structure, combined with the material, can kill several types of germs and inhibit bacterial growth with a 99% effectiveness rate. Specifically, the structures employed cause mechanical damage to cell membranes, thus killing pathogens.
This strategy will guarantee patients and medical staff’s health protection and bring considerable economic benefits, as spending on detergents and disinfectants will be reduced. A promising solution requiring various steps and contributions from the ten project partners.
In this sense, the researchers from the University of Alicante’s NANOBIOPOL group, Alfonso Jiménez, María del Carmen Garrigós and Carlos Pelegrín, are designing formulations with antimicrobial properties from essential oils extracted from plants such as thyme or oregano, for use as bactericidal agents. According to Jiménez, “our main role is to develop the polypropylene film with the antimicrobial essential oils in the laboratory. These oils are extracted from natural plants such as thyme or rosemary, which can be found near Alicante and are integrated in the basic material of the film”.
Applications
These antimicrobial plastic films will be used in hospitals to reduce infection risk. In this regard, FLEXPOL’s main goal is for the material to be used on large surfaces, such as walls and floors, as well as on smaller ones, like tables, beds or doorknobs, where more and more bacteria grow. For this reason, the product will be tested in actual medical environments, namely at Donostia University Hospital, a project partner, to evaluate how effective, durable and infection-resistant these films are, as well as their compatibility with the cleaning and disinfection protocols in place.
FLEXPOL meeting at the UA
On 23 and 24 January 2018, the UA San Vicente del Raspeig campus hosted a meeting of the FLEXPOL project consortium, formed by Germany’s Fraunhofer Institute for Production Technology (IPT), project coordinator; Naturality, Propagroup S.p.A. and Granta Design Ltd. (a Spanish, an Italian and a British company, respectively); two research centres, IK4-TENIKER and the Catalan Institute for Nanoscience and Nanotechnology (ICN2); the Universities of Alicante and Minho, Portugal; and Donostia University Hospital.
The FLEXPOL project, launched in January 2017, will be running for three years and is set to receive €5.17 million of funding from the European Union.

Source: Asociación RUVID

Cristale de divizare pentru conductivitatea metalică 2D(Splitting crystals for 2D metallic conductivity)

Materialele sunt fabricate din atomi de stronțiu, niobiu și oxigen, cu o structură stratificată derivată din perovskit. Acești compuși ai niobatului de stronțiu promite dezvoltarea electronică avansată datorită conductivității metalice cvasi-dimensionale.

Posted: Feb 21, 2018
Splitting crystals for 2D metallic conductivity (Nanowerk News) Adding oxygen atoms to a perovskite-like crystal material splits it into layers, giving it unique electrical properties.
Sheets of electrons that are highly mobile in only two dimensions, known as 2D electron gas, have unique properties that can be leveraged for faster and novel electronic devices. Researchers have been exploring 2D electron gas, which was only discovered in 2004, to see how it can be used in superconductors, actuators, and electronic memory devices, among others.
Researchers at Japan’s Tohoku University, with an international team of colleagues, recently identified the atomic structure of a group of perovskite-related materials showing interesting 2D conductive properties.

The scanning transmission electron micrograph shows that the atomic structure was alternately arranged in the three-layer and the zig-zag two-layer thick chain-like slabs, showing quasi-1D metallic conductivity in the former.
The materials are made of strontium, niobium and oxygen atoms, with a layered structure derived from perovskite. These strontium niobate compounds show promise for developing advanced electronics because of their ‘quasi-one-dimensional’ metallic conductivity.
Yuichi Ikuhara of Tohoku University’s Advanced Institute for Materials Research with Johannes Georg Bednorz of Zürich Research Laboratory and colleagues used atom-resolved scanning transmission electron microscopy combined with theoretical calculations to learn how adding oxygen atoms to strontium niobates affects their conductivity. Four different materials formed depending on the concentration of oxygen atoms.
The researchers found that three of the materials were conductors of electricity while the fourth was an insulator. At the atomic scale, they discovered the materials were formed of alternating chain-like and zigzag slabs. Depending on the concentration of oxygen atoms, the chain-like slabs were two, three, or four layers thick, sometimes varying within the same material. The zigzag slabs were insulating layers in all the materials, while the chain-like slabs were conducting layers in three of the four materials.
The team determined that local electrical conductivity within the material directly depended on the shapes of the niobate octahedra in the layers. When positive ions of niobium were displaced toward the centers of the niobate octahedra, a local conducting nature was induced.
2D conducting layers are commonly formed by creating an interface between two insulators. It should now be possible to achieve the same goal by segmenting 3D conducting materials into stacks of 2D conducting layers separated by insulating layers, the researchers say in their study published in the journal ACS Nano, („Atomic-Scale Origin of the Quasi-One-Dimensional Metallic Conductivity in Strontium Niobates with Perovskite-Related Layered Structures”). This could lead to applications in the development of 2D electrical conducting materials and devices.

Source: Tohoku University

Memorile MEMS obțin metatlenses(MEMS chips get metatlenses)

Lentilă plată bazată pe metasurface integrată pe un scaner MEMS: Micrografie electronică de scanare (stânga) și imagine microscopie optică (dreapta) a unui dispozitiv lentilă-MEMS. Integrarea dispozitivelor MEMS cu metalenze va ajuta la crearea unei noi paradigme pentru manipularea luminii prin combinarea puterii acestor tehnologii: control dinamic de mare viteză cu manipulare spațială precisă a frontelor de undă. Mai mult decât atât, această integrare a obiectivelor cu lentile plate bazate pe metasurface cu scanerele MEMS poate fi extinsă la părțile vizibile și la alte părți ale spectrului electromagnetic, implicând potențialul de aplicare pe câmpuri mai largi, cum ar fi sistemele microscopice bazate pe MEMS, imagistică holografică și de proiecție, scanere LIDAR (detectarea și măsurarea luminii) și imprimare laser. „

Posted: Feb 21, 2018
MEMS chips get metatlenses (Nanowerk News) Lens technologies have advanced across all scales, from digital cameras and high bandwidth in fiber optics to the LIGO lab instruments. Now, a new lens technology that could be produced using standard computer-chip technology is emerging and could replace the bulky layers and complex geometries of traditional curved lenses.
Flat lenses, unlike their traditional counterparts, are relatively lightweight, based on optical nanomaterials known as metasurfaces. When the subwavelength nanostructures of a metasurface form certain repeated patterns, they mimic the complex curvatures that refract light, but with less bulk and an improved ability to focus light with reduced distortion. However, most of these nanostructured devices are static, which limits their functionality.
Federico Capasso, an applied physicist at Harvard University who pioneered metalens technology, and Daniel Lopez, group leader of nanofabrication and devices at Argonne National Laboratory and an early developer of microelectromechanical systems (MEMS), brainstormed about adding motion capabilities like fast scanning and beam steering to metalenses for new applications.

Metasurface-based flat lens integrated onto a MEMS scanner: Scanning electron micrograph (left) and optical microscope image (right) of a lens-on-MEMS device. Integration of MEMS devices with metalenses will help to create a new paradigm to manipulate light by combining the strength of these technologies: high-speed dynamic control with precise spatial manipulation of wave-fronts. (Image: Center for Nanoscale Materials, Argonne National Lab)
Capasso and Lopez developed a device that integrates mid-infrared spectrum metalenses onto MEMS. The researchers report their findings this week in APL Photonics („Dynamic metasurface lens based on MEMS technology”).
MEMS is a circuit-based technology that incorporates microelectronics, like those found in computer chips, and includes mechanical microstructures like actuators and gears. Ubiquitous in everything from cellphones to airbags, biosensing devices, appliances and optics, MEMS are fabricated using the same techniques used for integrated circuits on typical computer chips.
“Dense integration of thousands of individually controlled lens-on-MEMS devices onto a single silicon chip would allow an unprecedented degree of control and manipulation of the optical field,” Lopez Said.
The researchers formed the metasurface lens using standard photolithography techniques on a silicon-on-insulator wafer with a 2-micron-thick top device layer, a 200-nanometer buried-oxide layer, and a 600-micron-thick handle layer. Then, they placed the flat lens onto a MEMS scanner, essentially a micromirror that deflects light for high-speed optical path length modulation. They aligned the lens with the MEMS’ central platform and fixed them together by depositing small platinum patches.
“Our MEMS-integrated metasurface lens prototype can be electrically controlled to vary the angular rotation of a flat lens and can scan the focal spot by several degrees,” Lopez said. “Furthermore, this proof-of-concept integration of metasurface-based flat lenses with MEMS scanners can be extended to the visible and other parts of the electromagnetic spectrum, implying the potential for application across wider fields, such as MEMS-based microscope systems, holographic and projection imaging, LIDAR (light detection and ranging) scanners and laser printing.”
When electrostatically actuated, the MEMS platform controls the angle of the lens along two orthogonal axes, allowing the scanning of the flat lens focal spot by about 9 degrees in each direction. The researchers estimate that the focusing efficiency is about 85 percent.
“Such metalenses can be mass produced with the same computer-chip fabrication technology and in the future, will replace conventional lenses in a wide range of applications,” Capasso said.

Source: American Institute of Physics

Detectarea rapidă a reziduurilor de pesticide cu nanoparticule(Rapid detection of pesticide residue with nanoparticles)

a dezvoltat nanoparticule magnetice acoperite cu polistiren pentru a detecta cantitățile de piretroide din probele de legume cu frunze. Aceste nanoparticule cu miezuri magnetice, atunci când sunt adăugate în scopuri de screening la o probă lichidă din culturi vegetale, pot atrage în mod eficient compușii piretroizi. Nanoparticulele pot fi apoi separate ușor de restul eșantionului prin mijloace magnetice pentru analiză.

Posted: Feb 21, 2018
Rapid detection of pesticide residue with nanoparticles (Nanowerk News) NUS food scientists have developed polystyrene coated magnetic nanoparticles which allow rapid screening of trace amounts of pesticide residue in vegetable crops (Food Chemistry, „Pyrethroid residue determination in organic and conventional vegetables using liquid-solid extraction coupled with magnetic solid phase extraction based on polystyrene-coated magnetic nanoparticles”).

Figure illustrates the process involved in using the polystyrene coated magnetic nanoparticles (“micro magnets”) to extract trace pesticide residues from vegetable samples. (Image: Yu Xi)
Pesticides are often used in vegetable farming to increase crop yield by controlling agricultural pests that can damage crops. Pyrethroids are a type of synthetic pesticide which are widely applied to crops. However, there are increasing concerns with pyrethroid residue on vegetables as long-term exposure may lead to health issues.
A research team led by Prof YANG Hongshun from the Food Science & Technology Programme at the Department of Chemistry, NUS has developed polystyrene coated magnetic nanoparticles to detect trace amounts of pyrethroids in leafy vegetable samples. These nanoparticles with magnetic cores, when added for screening purposes to a liquid sample of vegetable crops, can effectively attract the pyrethroid compounds. The nanoparticles can then be separated easily from the rest of the sample by magnetic means for analysis.

Transmission electron microscopy image of the polystyrene coated magnetic nanoparticles. The nanoparticles have a diameter of about 20 nm. (Image: NUS)
Conventional screening methods typically use tedious processes such as filtration and centrifugation to isolate and ascertain the presence of pyrethroids. The approach developed by Prof Yang and his team is a simpler process in which the extraction process can be completed within an hour. Possible applications could include vegetable screening and monitoring programmes to improve food supply safety.
Ms YU Xi, a Ph.D. student working on the project said, “In terms of the accuracy, the recovery rates in our experiments for five kinds of commonly used pyrethroids were greater than 91.6%, which is comparable to conventional methods. This method is also more cost effective as the nanoparticles can be washed and recycled after use.”
“Chemical residue in food products is an important food safety issue for consumers. This method offers a fast and effective way to screen vegetable samples for residue pesticides. It can potentially be adapted for other types of food samples. With small modifications, various food products such as fruits, nuts, meat and vegetable oils can also be tested using this method for possible food hazards,” added Prof Yang.

Source: National University of Singapore

Cristalele robotice care merg pe jos(Robotic crystals that walk n’roll)

Ei au dezvoltat cristale robotice care merg încet ca un vierme și se rostogolesc de 20.000 de ori mai repede decât viteza de mers pe jos. Aceste cristale organice în mișcare, au un potențial mare ca material pentru roboți moi în viitor, în special în domeniul medical.Cristalele noastre ar putea fi folosite ca un nou tip de material pentru roboți moi, cu o siguranță și confort îmbunătățite. În timp ce societatea noastră se îmbătrânește, trebuie să luăm în considerare relația simbiotică dintre oameni și roboți, deoarece roboții pot avea grijă de oameni, inclusiv de vârstnici, în viitorul apropiat „.

Posted: Feb 21, 2018
Robotic crystals that walk n’roll (Nanowerk News) Scientists at Waseda University may have come a step closer to innovating soft robots to care for people. Its material, however, is something you may have never expected.
They have developed robotic crystals that walk slowly like an inchworm and roll 20,000 times faster than its walking speed. These autonomously moving, organic crystals have great potential as material for soft robots in the future, especially in the medical field.

“The crystals are flexible, durable and lightweight,” says Hideko Koshima, a visiting professor at Waseda’s Research Organization for Nano & Life Innovation. “They could possibly be used as material for microrobots which transport substances in the microscopic region, for instance, carrying egg cells for infertility treatment or conducting invasive surgery.”
Their study was published in Nature Communications („Walking and rolling of crystals induced thermally by phase transition”).
Crystals have been expected to play an important role as locomotive material for soft robots, and its mechanical motion has been explored in terms of bending and expansion/contraction. However, more variety in movements was sought for.
Previously in 2016, Koshima’s research group reported that chiral azobenzene crystals, which were also used in the recent study, bend with exposure to light. During this investigation, the crystals were found to undergo phase transition at 145°C without fracturing, even after repeated heating and cooling.

Based on these findings, they designed the robotic crystals demonstrating two different modes of locomotion: walking and rolling.
Using an infrared thermography camera and a digital optical microscope, the group observed that thin, long plate-like crystals with thickness gradient in the longitudinal direction walked slowly like an inchworm through repeated bending and straightening under heating and cooling cycles near the transition temperature on a hot plate, moving 1.5mm in 30 minutes. On the other hand, thinner, longer plate-like crystals with width gradient rolled 3.1mm in 0.2 seconds, accelerated by tilted bending then flipping, under only one process of heating and cooling.
“The driving force behind the walking and rolling locomotion was generated from the unsymmetrical shape of the crystals,” Koshima explains.
Although the scientists would need to further study how to precisely control the direction and speed of the robotic crystals for practical application, this finding opens a door to a new field of crystal robotics, and on a larger scale, brings us a step closer to addressing issues related to population aging.

“Currently, robots are rigid and heavy, making them unsuitable for daily interaction with humans,” points out Koshima. “Our crystals could be used as a new kind of material for soft robots with improved safety and comfort. As our society ages, we must consider the symbiotic relationship between humans and robots, since robots may look after people, including the elderly, in the near future.”
Koshima is now attempting to produce robotic crystals which undergo phase transition at a much lower temperature.

Source: Waseda University

Tuning surse de lumină cuantică(Tuning quantum light sources)

au modificat chimic tuburi mici de atomi de carbon. Aceste tuburi sunt primul material care emite fotoni singuri la temperatura camerei și lungimi de undă ale telecomunicațiilor. Nici un alt sistem de materiale nu a putut să îndeplinească simultan aceste două condiții critice de operare

Posted: Feb 21, 2018
Tuning quantum light sources (Nanowerk News) Knowing the details of the quantum world—electrons and packets of light called photons—could radically improve computers and sensors. A critical component to making devices that harness the quantum world is a source that emits a regular stream of single photons.
Scientists at the Center for Integrated Nanotechnologies and their colleagues chemically modified tiny tubes of carbon atoms. These tubes are the first material to emit single photons at room temperature and telecom wavelengths. No other material system has been able to meet these two critical operational conditions simultaneously (Nature Photonics, „Tunable room-temperature single-photon emission at telecom wavelengths from sp3 defects in carbon nanotubes”).

The schematic shows the emission of a single photon (red) from a chemically modified carbon nanotube when excited by green light. (Image: Xiaowei He, Center for Integrated Nanotechnologies, Los Alamos)
This critical combination of features makes integrating devices that exploit the quantum world with existing optical networks a very real possibility. That is, the carbon nanotubes that allow for ultra secure data encryption could be used with today’s telecom network. The carbon nanotubes could also be integrated into devices for more sensitive sensors and future quantum computers.
The ability to integrate fiber-based quantum information technology into existing optical networks would be a significant step towards applications in quantum communication. To achieve this, quantum light sources must be able to emit single photons at telecommunication wavelengths and at room temperature.
This combination of features has been elusive until now, despite two decades of research efforts. Some systems (e.g., self-assembled quantum dots) emit at telecommunication wavelengths but require cryogenic cooling. Other systems (for example, diamond nitrogen-vacancy centers) operate at room temperature but can only emit in the visible spectral range.
Scientists at the Center for Integrated Nanotechnologies and their collaborators have produced functionalized carbon nanotubes that have both of these critical features. Carbon nanotubes had been previously identified as a promising quantum light source; however, the unstable photon emissions they generated were problematic.
The answer uncovered by scientists at the Center for Integrated Nanotechnologies was to chemically modify the nanotubes through aryl-diazonium reactions. This introduced defects to the nanotubes that allowed for controllable single-photon emission at both room temperature and telecommunication wavelengths. The team also demonstrated that the emission wavelength was tunable. Just as the tension and length of a violin string can be adjusted to achieve different frequencies, the diameter of the functionalized carbon nanotubes can be varied to generate different emission wavelengths.
Not only do these results have significance for basic science, including functionalization chemistry and quantum metrology, but they also open the door to exciting developments in quantum technologies.

Source: U.S. Department of Energy, Office of Science

Nanomushroom sensors: One material, many applications

Counting Dividing Cells

Scaling Up

Researchers combine metalens with an artificial muscle (w/video)

Researchers turn light upside down

Concrete infused with wood nanocrystals is stronger

Remembering really fast

Innovative antimicrobial adhesive films to reduce infection risk in hospitals

Applications

FLEXPOL meeting at the UA

Splitting crystals for 2D metallic conductivity

MEMS chips get metatlenses

Rapid detection of pesticide residue with nanoparticles

Robotic crystals that walk n’roll

Tuning quantum light sources