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Nanotechnology for self-powered systems

Nanotechnology for self-powered systems | Amazing Science | Scoop.it

There is an almost infinite number of mechanical energy sources all around us – basically, anything that moves can be harvested for energy. These environmental energy sources can the very large, like wave power in the oceans, or very small, like rain drops or biomechanical energy from heart beat, breathing, and blood flow. With the increasing use of nanotechnology materials and applications in energy research, scientists are finding more and more ways to tap into these pretty much limitless sources of energy.


The continued miniaturization of portable electronics is increasingly challenged by the reliance on conventional battery technology. But for the near future, micro- and even nanoscale devices will be widely used in health monitoring; infrastructure and environmental monitoring; internet of things; and of course defense technologies. In these application areas, battery design will have to go way beyond today's typical lithium-ion batteries. Rather than relying on stored power, nanodevices will probably rely on novel, also nanoscale, power sources.


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Cobalt Oxide Nanoparticles Can Split Water Into Hydrogen and Oxygen Using Natural Sunlight

Cobalt Oxide Nanoparticles Can Split Water Into Hydrogen and Oxygen Using Natural Sunlight | Amazing Science | Scoop.it

Researchers from the University of Houston have found a catalyst that can quickly generate hydrogen from water using sunlight, potentially creating a clean and renewable source of energy. Their research, published in Nature Nanotechnology, involved the use of cobalt oxide nanoparticles to split water into hydrogen and oxygen.


Jiming Bao, lead author of the paper and an assistant professor in the Department of Electrical and Computer Engineering at UH, said the research discovered a new photocatalyst and demonstrated the potential of nanotechnology in engineering a material’s property, although more work remains to be done.


Bao said photocatalytic water-splitting experiments have been tried since the 1970s, but this was the first to use cobalt oxide and the first to use neutral water under visible light at a high energy conversion efficiency without co-catalysts or sacrificial chemicals. The project involved researchers from UH, along with those from Sam Houston State University, the Chinese Academy of Sciences, Texas State University, Carl Zeiss Microscopy LLC, and Sichuan University.


Researchers prepared the nanoparticles in two ways, using femtosecond laser ablation and through mechanical ball milling. Despite some differences, Bao said both worked equally well.

Different sources of light were used, ranging from a laser to white light simulating the solar spectrum. He said he would expect the reaction to work equally well using natural sunlight.


Once the nanoparticles are added and light applied, the water separates into hydrogen and oxygen almost immediately, producing twice as much hydrogen as oxygen, as expected from the 2:1 hydrogen to oxygen ratio in H2O water molecules, Bao said.


The experiment has potential as a source of renewable fuel, but at a solar-to-hydrogen efficiency rate of around 5 percent, the conversion rate is still too low to be commercially viable. Bao suggested a more feasible efficiency rate would be about 10 percent, meaning that 10 percent of the incident solar energy will be converted to hydrogen chemical energy by the process.


Other issues remain to be resolved, as well, including reducing costs and extending the lifespan of cobalt oxide nanoparticles, which the researchers found became deactivated after about an hour of reaction.

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Free-swimming, self-propelled micromotors to clean up polluted water

Free-swimming, self-propelled micromotors to clean up polluted water | Amazing Science | Scoop.it
Researchers in Germany have invented micromotors that can propel themselves through water while degrading organic pollutants. The micromotors, which run on dilute hydrogen peroxide, could be used to clean up small reservoirs, pipes and other hard to reach places.


Organic pollutants are found in many industrial wastewaters, including those of textile companies, pharmaceutical companies and agriculture. They are an increasing problem, because they are often resistant to environmental degradation and cannot be processed with conventional biological or chemical water treatments.

 

Micromotors could help. Last year, building on previous uses of micromotors as on-chip biosensors and cell transporters, Joseph Wang, at the University of California, San Diego in the US, and colleagues developed self-propelled micromotors that could capture oil droplets – thereby offering a means to clean up small oil spills. Only now, however, have micromotors been used to actually degrade pollutants. ‘This study indicates the great potential of micromotors for environmental monitoring and remediation,’ says Wang.

 

Developed by Samuel Sanchez and colleagues at the Leibniz Institute for Solid State and Materials Research (IFW) the latest micromotors consist of a tubular core of platinum that is surrounded by iron. Releasing them into polluted water containing dilute hydrogen peroxide results in the motors’ platinum cores converting the peroxide into oxygen bubbles and the surrounding iron produces hydroxyl radicals. The bubbles propel the micromotors along, while the hydroxyl radicals oxidise organic pollutants.

 

Two experts in micromotors, Ayusman Sen at Penn State University in the US and Martin Pumera at Nanyang Technological University in Singapore, both say that the big advantage of the micromotors is their self-propulsion, which speeds up reaction rates and, therefore, quickly degrades pollutants. ‘The hydroxyl radicals can reach the target pollutant molecules much faster than would be possible by simple diffusion,’ says Pumera.

 

The micromotors would probably not be able to remediate ‘huge amounts’ of waste water, says Sanchez. ‘We aim to clean contaminated capillaries, small pipes and places difficult to reach,’ he adds. ‘We are dealing with applications especially for the microscale and environments hard to get to.’

 

Li Zhang at the Chinese University of Hong Kong says the results are ‘striking’, and hold promise for environmental applications. ‘To date, though several research groups have been working on micromotors, they have mainly put great efforts on biological and biomedical applications,’ he says. ‘It is apparent that for industrial application, such as wastewater treatment, this process needs to be further scaled-up and the micromotors require multi-functionality. I think it is worth doing those trials and continuing this research topic.’

   
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The first step has been taken towards developing a nanorobot to deliver drugs inside the body

The first step has been taken towards developing a nanorobot to deliver drugs inside the body | Amazing Science | Scoop.it

Using DNA self-assembly, the Aarhus University researchers Magnus Stougaard, Oskar Franch and Brian Christensen designed eight unique DNA molecules from the body’s own natural molecules. When these molecules are mixed together, they spontaneously aggregate in a usable form – the nanocage (see figure).

 

The nanocage has four functional elements that transform themselves in response to changes in the surrounding temperature. These transformations either close (figure 1A) or open (figure 1B) the nanocage. By exploiting the temperature changes in the surroundings, the researchers trapped an active enzyme called horseradish peroxidase (HRP) in the nanocage (figure 1C). They used HRP as a model because its activity is easy to trace.

 

This is possible because the nanocage’s outer lattice has apertures with a smaller diameter than the central spherical cavity. This structure makes it possible to encapsulate enzymes or other molecules that are larger than the apertures in the lattice, but smaller than the central cavity.

 

The researchers have just published these results in the renowned journal ACS Nano. Here the researchers show how they can utilise temperature changes to open the nanocage and allow HRP to be encapsulated before it closes again.

 

They also show that HRP retains its enzyme activity inside the nanocage and converts substrate molecules that are small enough to penetrate the nanocage to products inside.

 

The encapsulation of HRP in the nanocage is reversible, in such a way that the nanocage is capable of releasing the HRP once more in reaction to temperature changes. The researchers also show that the DNA nanocage – with its enzyme load – can be taken up by cells in culture.

 

Looking towards the future, the concept behind this nanocage is expected to be used for drug delivery, i.e. as a means of transport for medicine that can target diseased cells in the body in order to achieve a more rapid and more beneficial effect.

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Elena Ortés's curator insight, December 5, 2013 8:13 AM

De gran ayuda en la lucha contra el cancer.

Directo al foco.

Dmitry Alexeev's curator insight, December 5, 2013 11:37 PM

drug delivery as well as novell instrument)

 

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Photon-plasmon nanowire laser offers new opportunities in light manipulation

Photon-plasmon nanowire laser offers new opportunities in light manipulation | Amazing Science | Scoop.it
Recently, researchers have been developing a new type of laser that combines photons and plasmons (electron density oscillations) into a single radiation-emitting device with unique properties.

 

The hybrid photon-plasmon nanowire laser is composed of a Ag nanowire and a CdSe nanowire coupled into an X-shape. This type of coupling enables the photonic and plasmonic modes to be separated, which gives the hybrid laser advantageous features.


"Compared to conventional photon lasers, the hybrid photon-plasmon nanowire laser offers two outstanding possibilities: the extremely thin laser beam (e.g., down to the size of a single molecule) and the ultrafast modulation (e.g., >THz repetition rate), both stemming from the longitudinally separable pure plasmon nanowire mode," Limin Tong, Professor at Zhejiang University in Hangzhou China, told Phys.org. "Owing to the above-mentioned merits, photon-plasmon lasers are potentially better for certain applications such as strong coupling of quantum nanoemitters, ultra-sensitivity optical sensing, and ultrafast-modulated coherent sources."


In a new study, the researchers have demonstrated that the photon and plasmon nanowire waveguides can be coupled in the longitudinal direction; that is, along the direction of the beams. This type of coupling makes it possible to spatially separate the plasmonic mode from the photonic mode, and to simultaneously use both modes. Under excitation, strong luminous spots are observed at both ends of the hybrid cavity, with interference rings indicating strong spatial coherence of the light emitted. The output spot of the Ag nanowire is much smaller than that of the CdSe nanowire, indicating much tighter confinement of the plasmon radiation.


The advantages of ultratight confinement and ultrafast modulation offered by side-coupling a plasmonic nanowire waveguide to a photonic one enable the hybrid laser to provide very precise lasing, which could be delivered to very small areas such as quantum dots. Photon-plasmon lasers can also have applications for nanophotonic circuits, biosensing, and quantum information processing. The researchers plan to make further improvements to the laser in the future.

 

"One of our future plans is to introduce the ultrafast nonlinear effects of the plasmonic nanowire into the hybrid laser, and explore the possibility of ultrafast-modulation of the nanolaser, while offering a far-field-accessible pure plasmon cavity mode with sub-diffration-limited beam size," Tong said.

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Detecting Molecules Through 14 mm Thick Bone

Detecting Molecules Through 14 mm Thick Bone | Amazing Science | Scoop.it

To understand the brain and its chemical complexities, researchers would like to peer inside the skull and observe neurotransmitters at work. Unfortunately, research methods to measure levels of certain chemicals in the brain require drilling holes in the skull, and noninvasive imaging techniques, such as MRI, can’t detect specific molecules. Now, as a first step toward a new imaging tool, researchers have shown that they can use Raman spectroscopy todetect chemical signatures through bone (J. Am. Chem. Soc. 2013, DOI: 10.1021/ja409378f).

 

With Raman spectroscopy, chemists can look for chemicals of interest sitting inside a range of materials, such as explosives inside plastic bottles. Richard P. Van Duyne’s group at Northwestern University has used the technique to monitor glucose levels through the skin of living rats (Anal. Chem. 2011, DOI: 10.1021/ac202343e).

 

To peer through bone, Sharma and colleagues combined two spectroscopic techniques: surface-enhanced and spatially offset Raman spectroscopy. Both methods involve exciting samples with laser light and then monitoring for specific Raman signals from the sample that are characteristic of a chemical of interest.

 

In the surface-enhanced variety, gold nanoparticles boost the Raman signal produced by molecules bound to their surfaces. The spatially offset method allows researchers to detect a useful signal from molecules located up to 20 mm within a sample. Researchers can isolate signals from these buried compounds by observing Raman signals at a different spot from where they shine the laser light. The separation ensures that the molecule’s signal isn’t dwarfed by scattered laser light from the sample’s surface.

 

As a test of the combination method, the researchers went to the market and bought a cut of lamb shoulder with a bone 3 to 8 mm thick. The human skull is 3 to 14 mm thick. The team then injected 90 trillion gold nanoparticles into the meat behind the bone. They had decorated the particles with a compound that has a strong Raman signature. When they shined 785-nm laser light on the bone, they could immediately detect the chemical signature of the reporter molecule. Sharma jumped up and down when she saw the results. “Everything I read and everyone we talked to said, ‘No, this shouldn’t work,’” through bone because the material isn’t transparent enough, Sharma says.

 

Right now the researchers cannot detect where the nanoparticles are located within the tissue, Van Duyne says, only that they are on the other side of the bone. And even with further refinements, the depth of tissue penetration is likely to be limited to areas close to the tissue’s outer surface.

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Organic semiconductor transistor made of a single nanoparticle achieves highest mobility yet

Organic semiconductor transistor made of a single nanoparticle achieves highest mobility yet | Amazing Science | Scoop.it

Organic semiconducting devices have many positive attributes, such as their low cost, high flexibility, light weight, and ease of processing. However, one drawback of organic semiconductors is that they generally have a low electron mobility, resulting in a weak current and poor conductivity.

 

In a new study, scientists from Taiwan have designed and built an organic semiconductor transistor with a mobility that is 2-3 orders of magnitude higher than that of conventional organic semiconductor transistors. The benefits of a high mobility could extend to a wide range of applications, such as organic LED displays, organic solar cells, and organic field-effect transistors.

The biggest reason for low electron mobility in conventional organic semiconductors is electron scattering due to structural defects in the form of grain boundaries. By designing an organic semiconductor transistor containing only a single grain, the scientists could avoid the problem of grain boundary scattering.

 

In their experiments, the researchers demonstrated that a device containing a single organic nanoparticle (perylene tetracarboxylic dianhydride, PTCDA) embedded in a nanopore and surrounded by electrodes achieves the highest electron mobility value to date by 1 order of magnitude, and is 2-3 orders of magnitude higher than the values reported for conventional organic semiconductor transistors made of polycrystalline films. The new device's mobility values are 0.08 cm2/Vs at room temperature and 0.5 cm2/Vs at a cool 80 K, which are approaching the intrinsic mobility of PTCDA.

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Strange Nanophotonic Materials Bend and Trap Light to Make Iridenscent Colors

Strange Nanophotonic Materials Bend and Trap Light to Make Iridenscent Colors | Amazing Science | Scoop.it

Normally, the colors we perceive are determined by the wavelengths of light reflected by objects in the world around us. But not all surfaces reflect light the same way. Picture an iridescent butterfly, for example. It might look drab from one direction, but explode into bright yellows or purples from another. That's because of microscopic structures that alter the way light bounces off the butterfly's wings.

 

At the NanoPhotonics Centre at the University of Cambridge, scientists are tinkering with tiny structures like the ones in butterfly wings to create crazy new materials that manipulate light and change color in strange ways.

 

“A lot of this stuff is not completely mainstream,” said Jeremy Baumberg, who directs the center. “People think it’s a bit weird.”

 

During a recent visit to Cambridge, I sat down with Baumberg to talk about some of the projects he and his colleagues -- engineers, physicists, chemists, materials scientists, and biologists -- are working on. This gallery shows off a few highlights.

 

The secrets behind these multicolored materials lie in the tiny nanostructures they’re made from: spheres, helices, tangled gyroids, lattices, super-thin membranes, and stacks. “The nice thing about all these materials is they’re a very visual example of nanotechnology,” Baumberg said. “The features and the color all come from structure.”


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New Trick Produces Whole Wafers of Perfectly Aligned Nanowires

New Trick Produces Whole Wafers of Perfectly Aligned Nanowires | Amazing Science | Scoop.it

Korean researchers use semiconductor manufacturing processes rather than chemical synthesis to build better nanowires faster.

 

Nanowires don’t quite get the recognition that their high-profile nanomaterial cousins carbon nanotubes and graphene receive. But nanowires are quietly leading toward big improvements in a new generation of photovoltaics, plastic OLEDs (organic light-emitting devices), and a bunch of other applications.

 

Nanowires have suffered from the same manufacturing issues that other nanomaterials have endured, namely achieving large scale production while maintaining quality. One of the key problems nanowire developers have had to overcome is getting the nanowires to orient themselves in perfectly even arrays.

 

Researchers at the Korea Advanced Institute of Science and Technology (KAIST) in cooperation with LG Innotek have found a solution to that problem. And that solution moves away from traditional chemical synthesis to toward tricks common to semiconductor manufacturing.

 

In research published in the journal Nano Letters (“High Throughput Ultralong (20 cm) Nanowire Fabrication Using a Wafer-Scale Nanograting Template”), the Korean team leveraged semiconductor processes  to produce highly-ordered and arrays of long (up to 20 centimeters) nanowires, eliminating the need for post-production arrangement.

 

The process involves a photo engraving technique on a 20-centimeter diameter silicon wafer. First the researchers created a template on the wafer consisting of an ultrafine 100-nanometer linear grid pattern. Then they used this pattern to lay down the nanowires using a sputtering process. The method produces nanowires in bulk in perfect shapes of 50-nm width and 20 cm maximum length.

 

“The significance is in resolving the issues in traditional technology, such as low productivity, long manufacturing time, restrictions in material synthesis, and nanowire alignment,” commented Professor Jun-Bo Yoon of KAIST in a press release. “Nanowires have not been widely applied in the industry, but this technology will bring forward the commercialization of high performance semiconductors, optic devices, and biodevices that make use of nanowires.”

 

Because the process doesn’t require a long synthesis time and results in perfectly aligned nanowires, the industrial partners in the research believe that it’s a technique that should lend itself to commercialization.

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Iron Nano-Ants: Light-activated colloidal dockers to haul huge loads

Iron Nano-Ants: Light-activated colloidal dockers to haul huge loads | Amazing Science | Scoop.it
Beads of haematite can pick up and carry other particles more than 10 times their size with the flick of a switch

 

Ant-like beads of haematite could be the giants of nanoscale construction. Tiny particles of the iron mineral have been made to pick up and carry cargo more than 10 times their size. The feat could be used in targeted drug delivery or building artificial muscles.

Iron-based nanoparticles are ideal cargo-carriers because they can be steered using magnetic fields or by following a thinly etched track. Previous versions relied on chemical glues to pick up stuff, but getting them to drop it has proved difficult.

 

To tackle that problem, Jérémie Palacci at New York University and his colleagues started by suspending haematite nano-beads and a variety of cargo particles in a hydrogen peroxide solution. Shining a light gave the haematite electrical charge, which broke bonds in the neighbouring solution.

 

The resulting halo of water and oxygen was not in chemical balance with its surroundings, a disturbance which drew larger particles to the beads. A bead and its cargo could then be steered together. To make the bead release its load, the team simply turned off the light.

 

"The drop-off has been problematic in other papers. We had to come up with really jerry-rigged situations in order to do it," says Ayusman Sen at Pennsylvania State University in University Park, who was not involved in the new work. "They have a better way of picking up and dropping particles than anyone else." The same iron bead can even be used repeatedly to round up a whole flock of larger particles.

 

Palacci's team envision using the nano-beads in future micro-manufacturing plants, for instance, to create artificial muscles by laying down the required particles and building fibres along tiny tracks. "That would be really cool," he says. "If you can make that, you can start thinking about everything muscles are used for in biology and try to see if you can mimic it."

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Mixing and Matching DNA-based Nanoparticles to Make Multifunctional Materials

Mixing and Matching DNA-based Nanoparticles to Make Multifunctional Materials | Amazing Science | Scoop.it
Standardized technique for combining different types of nanoparticles to produce large-scale composite materials opens remarkable opportunities for 'mix and match' materials fabrication.

 

Scientists at the U.S. Department of Energy's Brookhaven National Laboratory have developed a general approach for combining different types of nanoparticles to produce large-scale composite materials. The technique, described in a paper published online by Nature Nanotechnology on October 20, 2013, opens many opportunities for mixing and matching particles with different magnetic, optical, or chemical properties to form new, multifunctional materials or materials with enhanced performance for a wide range of potential applications. 


The approach takes advantage of the attractive pairing of complementary strands of synthetic DNA—based on the molecule that carries the genetic code in its sequence of matched bases known by the letters A, T, G, and C. After coating the nanoparticles with a chemically standardized "construction platform" and adding extender molecules to which DNA can easily bind, the scientists attach complementary lab-designed DNA strands to the two different kinds of nanoparticles they want to link up. The natural pairing of the matching strands then "self-assembles" the particles into a three-dimensional array consisting of billions of particles. Varying the length of the DNA linkers, their surface density on particles, and other factors gives scientists the ability to control and optimize different types of newly formed materials and their properties.


"Our study demonstrates that DNA-driven assembly methods enable the by-design creation of large-scale 'superlattice' nanocomposites from a broad range of nanocomponents now available—including magnetic, catalytic, and fluorescent nanoparticles," said Brookhaven physicist Oleg Gang, who led the research at the Lab's Center for Functional Nanomaterials (CFN). "This advance builds on our previous work with simpler systems, where we demonstrated that pairing nanoparticles with different functions can affect the individual particles' performance, and it offers routes for the fabrication of new materials with combined, enhanced, or even brand new functions." 


Future applications could include quantum dots whose glowing fluorescence can be controlled by an external magnetic field for new kinds of switches or sensors; gold nanoparticles that synergistically enhance the brightness of quantum dots' fluorescent glow; or catalytic nanomaterials that absorb the "poisons" that normally degrade their performance, Gang said.

 

"Modern nano-synthesis methods provide scientists with diverse types of nanoparticles from a wide range of atomic elements," said Yugang Zhang, first author of the paper. "With our approach, scientists can explore pairings of these particles in a rational way." 

 

Pairing up dissimilar particles presents many challenges the scientists investigated in the work leading to this paper. To understand the fundamental aspects of various newly formed materials they used a wide range of techniques, including x-ray scattering studies at Brookhaven's National Synchrotron Light Source (NSLS) and spectroscopy and electron microcopy at the CFN.

 

For example, the scientists explored the effect of particle shape. "In principle, differently shaped particles don't want to coexist in one lattice," said Gang. "They either tend to separate into different phases like oil and water refusing to mix or form disordered structures." The scientists discovered that DNA not only helps the particles mix, but it can also improve order for such systems when a thicker DNA shell around the particles is used. 


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Electronics that dissolve in water could be used for medical implants or biodegradable gadgets

A team of researchers has designed flexible electronic components that can dissolve inside the body, and in water. The components could be used to make smart devices that disintegrate once they are no longer useful, helping to alleviate electronic waste and enabling the development of medical implants that don’t need to be surgically removed.

 

So far, the team has designed an imaging system that monitors tissue from within a mouse, a thermal patch that prevents infection after a surgical site is closed up, solar cells and strain and temperature sensors. The project is led by John Rogers, a materials scientist at the University of Illinois at Urbana-Champaign, and Fiorenzo Omenetto, a biomedical engineer at Tufts University in Medford, Massachusetts. The two say that after several years of work, they and their colleagues can now make just about any kind of dissolving, high-performance electronic or optical device.

 

The project really took off in 2009, when the researchers brought together Rogers’ expertise on flexible silicon electronics and Omenetto’s tough, biocompatible silk. The silk is made by processing and moulding proteins from silkworm cocoons to make thin sheets that conform and stick to tissues, such as the surface of the brain. By changing the processing conditions, Omenetto can control how long it takes the silk proteins to break down when wet. The researchers then placed Rogers’ silicon integrated circuits together with light-emitting diodes and other electronic devices on Omenetto’s silk. They've since demonstrated numerous devices, including brain interfaces that take very sensitive electrical measurements, but although the devices showed no adverse effects in early animal tests, they didn’t completely dissolve — the metals were left behind. And having silicon floating around under the skin is not ideal, says Omenetto.

 

Now, the researchers have figured out how to make every part of the system disintegrate. Rather than using stable metals such as copper or silver for electrical connections, they turned to magnesium. Magnesium is conductive, but it is also very reactive — especially in wet conditions — so isn't often used in electronic circuits. For dissolving electronics, however, that is an advantage. The team use magnesium to connect integrated circuits and to form antennas and wires that allow the devices to be powered from outside the body.

 

The other key is treating the silicon correctly. The team had something of a eureka moment about the material. “You don’t think of silicon as water soluble”, he says, because it would take 1,000 years for an average silicon wafer to dissolve. The thin silicon membranes in the dissolvable devices are less than 100 nanometres thick, and dissolve at about 4.5 nanometres a day. The team can control the degradation of the devices by tuning the properties of the silk, and by changing the thickness of the silicon and other materials.

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Bionanotechnology: Progressively Thinner Layers Of Chitin Make Metallic Beetles Shine

Bionanotechnology: Progressively Thinner Layers Of Chitin Make Metallic Beetles Shine | Amazing Science | Scoop.it

A team of researchers at the University of Costa Rica has found that the beetles' metallic appearance is created by the unique structural arrangements of many dozens of layers of exo-skeletal chitin in the elytron, a hardened forewing that protects the delicate hindwings that are folded underneath.

 

The beetles were captured in the University of Costa Rica's Alberto Brenes Mesén Biological Reserve, a tropical rainforest environment. "The metallic appearance of these beetles may allow them to be unnoticed, something that helps them against potential predators," says physicist and study leader William E. Vargas. The surface of their elytra "reflects light in a way that they look as bright spots seen from any direction," he explains. "In a tropical rainforest, there are many drops of water suspended from the leaves of trees at ground level, along with wet leaves, and these drops and wet leaves redirect light by refraction and reflection respectively, in different directions. Thus, metallic beetles manage to blend with the environment."

 

To interpret the cause of this metallic look, Vargas and his team assumed that a sequence of layers of chitin appears through the cuticle, with successive layers having slightly different refractive indices.. In these beetles, the cuticle, which is just 10 millionths of a meter deep, has some 70 separate layers of chitin—a nitrogen-containing complex sugar that creates the hard outer skeletons of insects, crabs, shrimps, and lobsters. The chitin layers become progressively thinner with depth, forming a so-called "chirped" structure.

 

"Because the layers have different refractive indices," Vargas says, "light propagates through them at different speeds. The light is refracted through—and reflected by—each interface giving, in particular, phase differences in the emerging reflected rays. For several wavelengths in the visible range, there are many reflected rays whose phase differences allow for constructive interference. This leads to the metallic appearance of the beetles."

 

This is similar to the way in which a prism breaks white light into the colors of the rainbow by refraction, but in the case of these beetles, different wavelengths, or colors of light are reflected back more strongly by different layers of chitin. This creates the initial palette of colors that enable the beetles to produce their distinctive hues. The mystery the researchers still needed to understand in more detail, however, was how the beetles could so perfectly create the structure causing the brilliant metallic tones of silver and gold.

 

Using a device they specially designed to measure the reflection of light when it strikes the curved surface of the beetles' elytra, Vargas and his colleagues found that as light strikes the interface between each successive layer (the first interface being the boundary between the outside air and the top chitin layer), some of its energy is reflected and some is transmitted down to the next interface. "This happens through the complete sequence of interfaces," Vargas says.

 

Because a portion of the light is reflected, it combines with light of the exact same wavelength as it passes back through layer upon layer of chitin, becoming brighter and more intense. Ocean waves can exhibit the same behavior, combining to produce rare but powerful rogue waves. In the case of the beetles, this "perfect storm" of light amplification produces not only the same colors but also the striking sheen and glimmer that we normally associate with fine jewelry.

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Cellulose nanocrystals found to have stiffness of steel

Cellulose nanocrystals found to have stiffness of steel | Amazing Science | Scoop.it

Applications range from electronics and medical devices to structural components for the automotive, civil and aerospace industries.


The same tiny cellulose crystals that give trees and plants their high strength, light weight and resilience, have now been shown to have the stiffness of steel. The nanocrystals might be used to create a new class of biomaterials with wide-ranging applications, such as strengthening construction materials and automotive components.


Calculations using precise models based on the atomic structure of cellulose show the crystals have a stiffness of 206 gigapascals, which is comparable to steel, said Pablo D. Zavattieri, a Purdue University assistant professor of civil engineering.


The nanocrystals are about 3 nanometers wide by 500 nanometers long, making them too small to study with light microscopes and difficult to measure with laboratory instruments.


The findings represent a milestone in understanding the fundamental mechanical behavior of the cellulose nanocrystals. “It is also the first step towards a multiscale modeling approach to understand and predict the behavior of individual crystals, the interaction between them, and their interaction with other materials,” Zavattieri said.


“This is important for the design of novel cellulose-based materials as other research groups are considering them for a huge variety of applications, ranging from electronics and medical devices to structural components for the automotive, civil and aerospace industries.”


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‘Zero-dimensional’ carbon nanotubes may lead to superthin/superfast electronics and synthetic cells

‘Zero-dimensional’ carbon nanotubes may lead to superthin/superfast electronics and synthetic cells | Amazing Science | Scoop.it

Piles of zero-dimensional carbon nanotubes appear as gold “mountains” a few nanometers high on a substrate, viewed by atomic force microscopy.


Synthetic, man-made cells and ultrathin electronics built from a new form of “zero-dimensional” carbon nanotube (CNT) may be possible, thanks to research at the University of Pittsburgh Swanson School of Engineering.


When created, single-wall carbon nanotubes (SWNTs) have a length-to-diameter ratio of up to 132,000,000:1 (think long wires that entangle, forming a one-dimensional structure). This clustering makes it difficult to achieve high purity, water solubility, and wet nanoscale applications, such a biological uses.


But what if the nanotube length could be reduced to roughly the size of its diameter — about 1 nanometer — thus creating a “zero-dimensional” carbon nanotube? That’s what Pitt researchers have achieved.


These extremely short nanotubes would be more soluble and would have the same dimensions as many proteins that compose the basic machinery of living cells. That suggests the potential for cell- or protein-level biomedical imaging, protein or nucleic acid vaccination carriers, drug-delivery vehicles, or even components of synthetic cells, the researchers say.


In addition, “zero-dimensional carbon nanotubes present the possibility to build ultrathin, superfast electronic devices, far superior to the best existing ones and it could be possible to build strong and ultralight cars, bridges, and airplanes,” said Steven R. Little, PhD, associate professor, CNG Faculty Fellow and Chair of the Department of Chemical and Petroleum Engineering, a principal investigator.


The researchers expect the process will be available commercially as soon as the process can be scaled up to manufacture bulk quantities, which is underway currently.


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Micro-robots will become soft and move like biological organisms, experts predict

Micro-robots will become soft and move like biological organisms, experts predict | Amazing Science | Scoop.it

Increasingly small robots can carry out their functions even inside the human body. No, this isn’t a sci-fi dream. The technology is almost ready. However there is still one condition they must meet to be effective: these devices need to have the same "softness" and flexibility as biological tissues.


This is the opinion of scientists like Antonio De Simone, from SISSA (the International School for Advanced Studies of Trieste) and Marino Arroyo from the Polytechnic University of Catalonia, who have just published a paper in the Journal of the Mechanics and Physics of Solids. Taking inspiration from unicellular water micro-organisms, they studied the locomotion mechanisms of "soft robots."

 

Forget cogwheels, pistons and levers: miniaturized robots of the future will be 'soft.' "If I think of the robots of tomorrow, what comes to mind are the tentacles of an octopus or the trunk of an elephant rather than the mechanical arm of a crane or the inner workings of a watch. And if I think of micro-robots then I think of unicellular organisms moving in water. The robots of the future will be increasingly like biological organisms" explains Antonio De Simone.


De Simone and his team at SISSA have been studying the movement of euglenids, unicellular aquatic animals, for several years. One of the aims of De Simone's research -- which has recently been awarded a European Research Council Advanced Grant of 1,300,000 euro -- is to transfer the knowledge acquired in euglenids to micro-robotics, a field that represents a promising challenge for the future. Micro-robots may in fact carry out a number of important functions, for example for human health, by delivering drugs directly to where they are needed, re-opening occluded blood vessels, or helping to close wounds, to name just a few.


To do this, these tiny robots will have to be able to move around efficiently. "Imagine trying to miniaturize a device made up of levers and cogwheels: you can't go below a certain minimal size. Instead, by mimicking biological systems we can go all the way down to cell size, and this is exactly the direction research is taking. We, in particular, are working on movement and studying how certain unicellular organisms with highly efficient locomotion move."

 

In their study, De Simone and Arroyo simulated euglenid species with different shapes and locomotion methods, based chiefly on cell body deformation and swelling, to describe in detail the mechanics and characteristics of the movement obtained.

 

"Our work not only helps to understand the movement mechanism of these unicellular organisms, but it provides a knowledge base to plan the locomotion system of future micro-robots."


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Super-thin membranes clear the way for chip-sized pumps

Super-thin membranes clear the way for chip-sized pumps | Amazing Science | Scoop.it

The ability to shrink laboratory-scale processes to automated chip-sized systems would revolutionize biotechnology and medicine. For example, inexpensive and highly portable devices that process blood samples to detect biological agents such as anthrax are needed by the U.S. military and for homeland security efforts. One of the challenges of "lab-on-a-chip" technology is the need for miniaturized pumps to move solutions through micro-channels. Electroosmotic pumps (EOPs), devices in which fluids appear to magically move through porous media in the presence of an electric field, are ideal because they can be readily miniaturized. EOPs however, require bulky, external power sources, which defeats the concept of portability. But a super-thin silicon membrane developed at the University of Rochester could now make it possible to drastically shrink the power source, paving the way for diagnostic devices the size of a credit card.

 

"Up until now, electroosmotic pumps have had to operate at a very high voltage—about 10 kilovolts," said James McGrath, associate professor of biomedical engineering. "Our device works in the range of one-quarter of a volt, which means it can be integrated into devices and powered with small batteries."

 

McGrath and his team use porous nanocrystalline silicon (pnc-Si) membranes that are microscopically thin—it takes more than one thousand stacked on top of each other to equal the width of a human hair. And that's what allows for a low-voltage system.

 

A porous membrane needs to be placed between two electrodes in order to create what's known as electroosmotic flow, which occurs when an electric field interacts with ions on a charged surface, causing fluids to move through channels. The membranes previously used in EOPs have resulted in a significant voltage drop between the electrodes, forcing engineers to begin with bulky, high-voltage power sources. The thin pnc Si membranes allow the electrodes to be placed much closer to each other, creating a much stronger electric field with a much smaller drop in voltage. As a result, a smaller power source is needed.

 

A microfluidic bioreactors consists of two chambers separated by a nanoporous silicon membrane. It allows for flow-based assays using minimal amounts of reagent. The ultra-thin silicon membrane provides an excellent mimic of biological barrier properties. The shown image combines two exposures in order to capture the brighter and darker parts of the scene, which exceed the dynamic range of the camera sensor. The resulting composite is truer to what the eye actually sees.

 

Along with medical applications, it's been suggested that EOPs could be used to cool electronic devices. As electronic devices get smaller, components are packed more tightly, making it easier for the devices to overheat. With miniature power supplies, it may be possible to use EOPs to help cool laptops and other portable electronic devices.

 

McGrath said there's one other benefit to the silicon membranes. "Due to scalable fabrication methods, the nanocrystalline silicon membranes are inexpensive to make and can be easily integrated on silicon or silica-based microfluid chips."

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Diamond ‘flaws’ may pave the way for nanoscale MRI and thermometry of single cells

Diamond ‘flaws’ may pave the way for nanoscale MRI and thermometry of single cells | Amazing Science | Scoop.it

Breakthrough offers high-sensitivity nanoscale sensors, and could lead to magnetic imaging of neuron activity and thermometry on a single living cell. - See more at:

 

By exploiting flaws in miniscule diamond fragments, researchers say they have achieved enough coherence of the magnetic moment inherent in these defects to harness their potential for precise quantum sensors in a material that is 'biocompatible'.

 

Nanoscopic thermal and magnetic field detectors - which can be inserted into living cells - could enhance our understanding of everything from chemical reactions within single cells to signalling in neural networks and the origin of magnetism in novel materials.

 

Atomic impurities in natural diamond structure give rise to the colour seen in rare and coveted pink, blue and yellow diamond. But these impurities are also a major research focus in emerging areas of quantum physics.

 

One such defect, the Nitrogen-vacancy Centre (NVC), consists of a gap in the crystal lattice next to a nitrogen atom. This system tightly traps electrons whose spin states can be manipulated with extreme precision.

Electron coherence - the extent to which the spins of these particles can sustain their quantum mechanical properties - has been achieved to high levels in the NVCs of large 'bulk' diamonds, with coherence times of an entire second in certain conditions - the longest yet seen in any solid material.

 

However in nanodiamonds - nanometer sized crystals that can be produced by milling conventional diamond - any acceptable degree of coherence has, until now, proved elusive.

 

Nanodiamonds offer the potential for both extraordinarily precise resolution, as they can be positioned at the nano-scale, and biocompatibility - as they have can be inserted into living cells. But without high levels of coherence in their NVCs to carry information, these unique nanodiamond benefits cannot be utilised.

 

By observing the spin dynamics in nanodiamond NVCs, researchers at Cambridge's Cavendish Laboratory, have now identified that it is the concentration of nitrogen impurities that impacts coherence rather than interactions with spins on the crystal surface.

 

By controlling the dynamics of these nitrogen impurities separately, they have increased NVC coherence times to a record 0.07 milliseconds longer than any previous report, an order of significant magnitude - putting nanodiamonds back in play as an extremely promising material for quantum sensing.

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Scientists create single-atom bit, smallest memory in the world

Scientists create single-atom bit, smallest memory in the world | Amazing Science | Scoop.it

Karlsruhe Institute of Technology (KIT) researchers have taken a big step towards miniaturizing magnetic data memory down to a single-atom bit: they fixed a single atom on a surface so the magnetic spin remained stable for ten minutes.

 

“A single atom fixed to a substrate is [typically] so sensitive that its magnetic orientation is stable only for less than a microsecond,” said Wulf Wulfhekel of KIT.

 

A compound of several million atoms has been needed to stabilize a magnetic bit longer than that. That’s because the magnetic moments of these atoms are normally easily destabilized by interactions with electrons, nuclear spins, and lattice vibrations of the substrate.

 

The finding opens up the possibility of designing more compact computer memories and could also be the basis for quantum computers, Wulfhekel said.

 

In their experiment, the researchers placed a single holmium atom onto a platinum substrate. At temperatures close to absolute zero (about 1 degree Kelvin), the atom was nearly vibration-free. They measured the magnetic orientation of the atom using the fine tip of a scanning tunneling microscope. The magnetic spin changed after about 10 minutes — “about a billion times longer than that of comparable atomic systems,” Wulfhekel said.


Reference: 

Toshio Miyamachi et al., Stabilizing the magnetic moment of single holmium atoms by symmetry, Nature, 2013, DOI: 10.1038/nature12759
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Wyss Institute at Harvard: "Watermark Ink" device (W-INK) wins R&D 100 Award

Wyss Institute at Harvard: "Watermark Ink" device (W-INK) wins R&D 100 Award | Amazing Science | Scoop.it

A device that can instantly identify unknown liquids based on their surface tension has been selected to receive the 2013 R&D 100 Award—known as “the Oscar of Innovation”—from R&D Magazine.

 

Invented in 2011 by a team of materials scientists and applied physicists at the Harvard School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering at Harvard, the “Watermark Ink” (W-INK) device offers a cheap, fast, and portable way to perform quality control tests and detect liquid contaminants.

 

W-INK fits in the palm of a hand and requires no power source. It exploits the chemical and optical properties of precisely nanostructured materials to distinguish liquids by their surface tension.

 

Winners of the R&D 100 Awards are selected by an independent judging panel and by the editors of R&D Magazine, which covers cutting-edge technologies and innovations for research scientists, engineers, and technical experts around the world.

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A single-atom light switch

A single-atom light switch | Amazing Science | Scoop.it

With just a single atom, light can be switched between two fiber optic cables at the Vienna University of Technology. Such a switch enables quantum phenomena to be used for information and communication technology.

 

Fiber optic cables are turned in to a quantum lab: scientists are trying to build optical switches at the smallest possible scale in order to manipulate light. At the Vienna University of Technology, this can now be done using a single atom. Conventional glass fibre cables, which are used for internet data transfer, can be interconnected by tiny quantum systems.

Professor Arno Rauschenbeutel and his team at the Vienna University of Technology capture light in so-called "bottle resonators". At the surface of these bulgy glass objects, light runs in circles. If such a resonator is brought into the vicinity of a glass fibre which is carrying light, the two systems couple and light can cross over from the glass fibre into the bottle resonator.

 

"When the circumference of the resonator matches the wavelength of the light, we can make one hundred percent of the light from the glass fiber go into the bottle resonator – and from there it can move on into a second glass fiber", explains Arno Rauschenbeutel.


This system, consisting of the incoming fiber, the resonator and the outgoing fiber, is extremely sensitive: "When we take a single Rubidium atom and bring it into contact with the resonator, the behaviour of the system can change dramatically", says Rauschenbeutel. If the light is in resonance with the atom, it is even possible to keep all the light in the original glass fiber, and none of it transfers to the bottle resonator and the outgoing glass fiber. The atom thus acts as a switch which redirects light one or the other fiber.

 

In the next step, the scientists plan to make use of the fact that the Rubidium atom can occupy different quantum states, only one of which interacts with the resonator. If the atom occupies the non-interacting quantum state, the light behaves as if the atom was not there. Thus, depending on the quantum state of the atom, light is sent into either of the two glass fibers. This opens up the possibility to exploit some of the most remarkable properties of quantum mechanics: "In quantum physics, objects can occupy different states at the same time", says Arno Rauschenbeutel. The atom can be prepared in such a way that it occupies both switch states at once. As a consequence, the states "light" and "no light" are simultaneously present in  each of the two glass fiber cables.

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How nanotechnology can advance regenerative medicine

How nanotechnology can advance regenerative medicine | Amazing Science | Scoop.it

Nanotechnology may provide new strategies for regenerative medicine, including better tools to improve or restore damaged tissues, according to a review paper that summarizes the current state of knowledge on nanotechnology with application to stem cell biology.

 

Researchers have found that the adhesion, growth, and differentiation of stem cells are likely controlled by their surrounding microenvironment, which contains both chemical and physical cues. These cues include the “nanotopography” of the complex extracellular matrix or architecture that forms a network for human tissues.

 

In their review paper published in the journal Science and Technology of Advanced Materials (open access), Yang-Kao Wang and colleagues describe studies showing how this nanotopography (which includes nanosized pores, grooves, ridges, etc.) plays important roles in the behavior and fate of stem cells.

 

The authors also discuss the application of nanoparticles to stem cell isolation, tracking and imaging; how to translate nanotechnology from two to three dimensions; and the potential limitations of using nanomaterials in stem cell biology.

 

The paper concludes that “understanding [the] interactions of nanomaterials with stem cells may provide knowledge applicable to [the development of improved] cell-scaffold combinations in tissue engineering and regenerative medicine.”

 


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Everything from ions to living cells can be directed to self-assemble using magnetic fields

Everything from ions to living cells can be directed to self-assemble using magnetic fields | Amazing Science | Scoop.it

Scientists in the US have devised a stunningly simple way to direct colloids to self-assemble in an almost infinite variety of configurations, in both two and three dimensions. The technique, which relies on the creation of a pre-determined pattern of magnetic fields to generate a ‘virtual mould’ to dictate the final position of the particles, can be used to separate and distribute, in a controlled way, anything from living cells to ions.

 

‘The concept is trivial,’ Bartosz Grzybowski, who led the research team at Northwestern University, cheerfully concedes. ‘Why no-one thought of it before now is a good question.’

 

The system consists of a patterned grid of nickel, generated by photolithography, embedded in a layer of poly(dimethyl siloxane) (PDMS). This is placed on a permanent magnet. This forms a patterned magnetic field on the grid: on the nickel the field is strong, on the adjacent ‘islands’ where there is no nickel, the field is weak.

 

When a colloidal mixture containing magnetic (paramagnetic) and non-magnetic (diamagnetic) particles is placed on the nickel grid and a magnetic field applied, the paramagnetic particles are drawn to the nickel regions, pushing aside any diamagnetic particles and directing them to the adjacent non-magnetic islands or voids.

 

The ability to construct three-dimensional architectures from the colloids also arises, given that the magnetic field penetrates the space above the nickel regions. An excess of diamagnetic colloid, for example, will coalesce on a low-field island to build a pillar. A further excess of particles can build bridges between pillars to produce arches. Such complex three-dimensional structures could be useful for electronic circuitry. To illustrate the versatility of the approach, the research team patterned a grid in such a way to fashion  a microscopic facsimile of the Blue Mosque in Istanbul, featuring large ‘domes’ connected by arches, and surrounded by four unconnected satellite domes.

 

‘For me, one of the main aspects of this work is in being able to position particles, and in particular living cells,’ says Grzybowski. ‘We should be able to address things that cannot be addressed by other means.’

Stefano Sacanna, who researches colloid self-assembly at New York University, says: ‘This is the kind of work that makes you think how come nobody has ever thought of this before?’ Sacanna says that while template-assisted self-assembly is a well-known technique the new work has ‘completely redefined this concept, introducing virtual magnetic moulds that can manipulate either paramagnetic or diamagnetic colloids simultaneously’.

 

‘Their idea of modulating magnetic fields at the micron-scale using a combination of paramagnetic fluids and magnetisable composite films is, in its simplicity, extremely powerful,’ he adds. ‘Not only can these virtual moulds extend in the third dimension, but they can also be switched on and off on demand, allowing for the creation of dynamic and reconfigurable three-dimensional colloidal architectures. As if this was not impressive enough already, they showed how magnetic moulds can manipulate objects other than colloids, including ions and colonies of – live! – bacteria. This work greatly extends our ability to manipulate colloidal matter and holds the promise for new exciting opportunities in nano-fabrication.’

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LOL  It often is...    ‘The concept is trivial,’ Bartosz Grzybowski, who led the research team at Northwestern University, cheerfully concedes. ‘Why no-one thought of it before now is a good question.’

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Cyborg gel implant fights can now be used to heal diabetes in mice

Cyborg gel implant fights can now be used to heal diabetes in mice | Amazing Science | Scoop.it

By implanting a transparent gel that contains genetically modified light-sensitive cells, researchers have demonstrated a new type of implant that could one day be used to treat disease and monitor toxins in people.

"Light is a great tool to interface with biological systems, but there is a fundamental problem. It gets scattered when it hits tissue, and at depths much thinner than our skin," says lead author Myunghwan Choi of Harvard Medical School in Boston.

 

Choi and his colleagues designed an implantable gel that could get around this, by guiding light under the mouse's skin. In experiments, the team impregnated the gel with different types of genetically modified cells before implanting it.

 

To control diabetes, the team shone light into the mouse and at the implanted gel using a fibre optic cable attached to its head. The light triggered cells in the gel to produce a compound that stimulated the secretion of insulin and stabilised blood glucose levels. Separately, the team also showed they could monitor for cadmium poisoning using cells that fluoresced when the mouse was under stress from the toxin.

 

Though still at the prototype stage, the ultimate idea is to reduce the need for doctors to perform repeated injections and blood tests to monitor or treat patients.

 

"The promise is there," agrees Fiorenzo Omenetto, a biotechnologist at Tufts University in Medford, Massachusetts. But he adds it will have to get a little easier to live with than the current implant. "The tough thing here is the presence of a large implant and a fibre sticking out of your head. Not something I'd want if I were diabetic."

 

Choi's team plans to work on making the gel more user-friendly. For example, he says, "we are thinking of adding a micro-LED with a wireless power receiver to the gel implant."

 

"Genetically modified cells have been engineered for a variety of applications ranging from the treatment of cancer to the prevention of gout," wrote Warren Chan of the University of Toronto, Canada, in a comment piece published alongside the work. "This suggests that the implantable hydrogel could be used for many biological and clinical applications."

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Cracked metal heals itself: Unexpected result shows that pulling apart makes cracks in metal fuse together

Cracked metal heals itself: Unexpected result shows that pulling apart makes cracks in metal fuse together | Amazing Science | Scoop.it

It was a result so unexpected that MIT researchers initially thought it must be a mistake: Under certain conditions, putting a cracked piece of metal under tension — that is, exerting a force that would be expected to pull it apart — has the reverse effect, causing the crack to close and its edges to fuse together.

The surprising finding could lead to self-healing materials that repair incipient damage before it has a chance to spread. The results were published in the journal Physical Review Letters in a paper by graduate student Guoqiang Xu and professor of materials science and engineering Michael Demkowicz.

“We had to go back and check,” Demkowicz says, when “instead of extending, [the crack] was closing up. First, we figured out that, indeed, nothing was wrong. The next question was: ‘Why is this happening?’”

The answer turned out to lie in how grain boundaries interact with cracks in the crystalline microstructure of a metal — in this case nickel, which is the basis for “superalloys” used in extreme environments, such as in deep-sea oil wells.

By creating a computer model of that microstructure and studying its response to various conditions, “We found that there is a mechanism that can, in principle, close cracks under any applied stress,” Demkowicz says. 


Most metals are made of tiny crystalline grains whose sizes and orientations can affect strength and other characteristics. But under certain conditions, Demkowicz and Xu found, stress “causes the microstructure to change: It can make grain boundaries migrate. This grain boundary migration is the key to healing the crack,” Demkowicz says.

The very idea that crystal grain boundaries could migrate within a solid metal has been extensively studied within the last decade, Demkowicz says. Self-healing, however, occurs only across a certain kind of boundary, he explains — one that extends partway into a grain, but not all the way through it. This creates a type of defect is known as a “disclination.”

Disclinations were first noticed a century ago, but had been considered “just a curiosity,” Demkowicz says. When he and Xu found the crack-healing behavior, he says, “it took us a while to convince ourselves that what we’re seeing are actually disclinations.”

These defects have intense stress fields, which “can be so strong, they actually reverse what an applied load would do,” Demkowicz says: In other words, when the two sides of a cracked material are pulled apart, instead of cracking further, it can heal. “The stress from the disclinations is leading to this unexpected behavior,” he says.

Having discovered this mechanism, the researchers plan to study how to design metal alloys so cracks would close and heal under loads typical of particular applications. Techniques for controlling the microstructure of alloys already exist, Demkowicz says, so it’s just a matter of figuring out how to achieve a desired result.

“That’s a field we’re just opening up,” he says. “How do you design a microstructure to self-heal? This is very new.” 

The technique might also apply to other kinds of failure mechanisms that affect metals, such as plastic flow instability — akin to stretching a piece of taffy until it breaks. Engineering metals’ microstructure to generate disclinations could slow the progression of this type of failure, Demkowicz says.

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