Posts Tagged ‘nanotech’
Tiny Battery Embedded In a Nanowire Is the Smallest Battery Yet
Now researchers at Rice University have , packing an entire lithium-ion battery into a single nanowire. The developers say it’s as small as such a device can possibly get.
Researchers led by Rice professor Pulickel Ajayan built a hybrid energy storage device, which serves as a battery and a supercapacitor. The first version sandwiched an electrolyte between a nickel/tin anode and a cathode made of a polymer called polyaniline. The cathode also served as a supercapacitor, storing lithium ions in bulk, as this explains. The prototype proved that lithium ions would move through the electrolyte and into the cathode.
Then Ajayan and colleagues incorporated this structure into a single nanowire, through a complicated process of etching and chemical washing. The goal is to make nanowires with ultra-thin separation between electrodes, so the device can remain as small as possible.
The completed wire-batteries are about 50 microns tall, which is roughly the diameter of a human hair, according to Rice.
For now, they can only charge and discharge about 20 times before they die, but researchers are trying to optimize them to last longer. The research is published in the journal ACS Nano Letters.
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Researchers Use DNA to Coax Quantum Dots Into Self-Assembling into a Light Antenna
Or, how to build artificial molecules
Quantum dots are those tiny pieces (like, nano-tiny) of semiconductor that can be customized to efficiently absorb and emit light in finely-tuned ways. They are interesting little particles, but thus far scientists haven’t really found a good way to coax different kinds of quantum dots into forming complex structures.
That’s really the major breakthrough here. Mashing up their knowledge of DNA and semiconductors, they devised a way to get these quantum dots to self organize. Says Ted Sargent, U. of Toronto professor and one of the research leads, in a :
The credit for this remarkable result actually goes to DNA: its high degree of specificity – its willingness to bind only to a complementary sequence – enabled us to build rationally-engineered, designer structures out of nanomaterials. The amazing thing is that our antennas built themselves – we coated different classes of nanoparticles with selected sequences of DNA, combined the different families in one beaker, and nature took its course. The result is a beautiful new set of self-assembled materials with exciting properties.
Just like radio antennas, the materials gather their medium--in this case light rather than electromagnetic wave--and increase the amount that is absorbed, channeling it to a single site within the structures where it can be concentrated. Plant leaves already do this and have been doing it for millennia, but this is the first time researchers have finessed nanoparticles into assembling themselves into similar structures. The result is a completely new generation of materials that potentially possess completely new applications.
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The First Self-Powering Nano-Device That Can Also Transmit Wireless Data
Publishing their findings in the journal ACS Nano Letters, the team describes a nanogenerator that turns mechanical vibrations scavenged from anything from a person’s pulse to a breeze to a person walking or cars driving over a bridge into electricity to power the device. That in and of itself isn’t so impressive, as such vibration-driven generators already existed previously.
The game-changer here is the fact that this nano-device can generate and store (in a capacitor) enough energy to also transmit wireless signals to a receiver up to 30 feet away via a transmitter roughly equivalent to those in Bluetooth headsets. The idea that something so small might be able to transmit data across distances could lead to new generations of medical sensors powered by a person’s own blood flow, environmental sensors powered by the ebb and flow of atmospheric air, and wearable sensors that run and transmit on the power leftover by the wearer’s own footsteps.
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New Nanometal Changes from Hard to Soft at the Flip of a Switch
The material is essentially an electrically tunable metal that can be hard and brittle or soft and malleable depending on the charge passing through it. To create the material, researchers placed precious metals like gold and platinum in an acidic bath, where corrosion cuts tiny porous channels or ducts through the metal. Those interior channels are then filled with a conductive liquid partner, like a diluted acid or saline solution.
Ions dissolved in the liquid can then influence the surface atoms of the metallic part of this metal-liquid combo. Depending on the charge applied to the liquid constituent, electrons are either added to or withdrawn from the metallic surface atoms, strengthening the material by double or making it more malleable and weaker (but more tolerant to damage) at will.
That’s a enviable quality for a metal to have. It opens the door to a variety of applications, including self-healing materials that can respond to stress in certain areas by becoming softer or harder as the situation commands.
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New Graphene Material is Paper-Thin and Ten Times Stronger Than Steel
This graphene paper is constructed of graphite reformed by chemical processes into monolayer hexagonal carbon lattices stacked as thin as a sheet of paper, and it is remarkably strong. To quote a from UTS:
Compared to steel, the prepared GP is six times lighter, five to six times lower density, two times harder with 10 times higher tensile strength and 13 times higher bending rigidity.
That’s no incremental improvement on the qualities of steel, but a huge leap forward in terms of overall material strength (plus, like paper, it is flexible). And because it is graphene, it is also imbued with some interesting electrical, thermal, and mechanical properties.
But perhaps best of all, graphene paper not outrageously difficult or expensive to manufacture, and as such it could have huge implications for the aviation and automotive industries, where manufacturers have already been turning to composites and carbon fiber materials to cut weight and thus increase fuel economies.
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Study Finds Commonly Used Silver Nanoparticles Are Deadly to Microbes, Plants
Among the millions of tons of nanoparticles manufactured annually, silver nanoparticles are a particular favorite as they work as antibacterial agents in surgical tools, water treatment, wound dressings, and in a variety of other roles. They’ve even been used in the cathodes of batteries.
And, if this study is correct, they are wreaking absolute havoc on critical soil systems that make plant life possible.
The researchers had begun to wonder what the impact of nanoparticles were on the environment, and having received a chunk of Arctic soil as part of the International Polar Year they decided to experiment on this piece of uncontaminated earth. They first studied the sample to see what kind of microbe communities were living in the soil, and identified a certain beneficial and prevalent microbe that helps fix nitrogen to plants. Plants can’t do this on their own and nitrogen is critical to their growth, so this particular microbe is essential to plant life.
The researchers then added three different kinds of nanoparticles to the soil and let it sit for six months. When they re-examined it, they found that this microbe had largely been extinguished, and laboratory analysis showed that silver nanoparticles were the culprit. Given the high number of silver nanoparticles slipping into the environment on a daily basis, such findings are concerning.
It’s but a single study that needs to be thoroughly replicated of course, but if confirmed it certainly wouldn’t be the first time humanity has rushed an innovation into the marketplace only to regret it later. The findings were published today in the Journal of Hazardous Materials, so hopefully the right people will give the findings a closer look.
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First 3-D Images of Nanoparticles Help Researchers Build New Nanoparticles
The method could illuminate how nanostructures work
Now a group of researchers in Europe have figured out a way to do it, and translate those pictures into that allow them to count individual atoms and see how they're arranged.
To take their nanopictures, Marta Rossell of ETH Zurich and Rolf Erni of the Swiss Federal Laboratories for Materials Science and Technology (EMPA) used a special electron microscope at Lawrence Berkeley National Laboratory. The machine has a resolution greater than the diameter of a single atom, allowing the researchers to zoom in on the nanoparticles’ atomic structures with great clarity.
They used silver nanoparticles in an aluminum matrix and tilted them under the electron beam to capture images. Then, Sandra Van Aert from the University of Antwerp built models based on those images, sharpening their resolution. Then Dutch tomography scientist Joost Batenburg used algorithms to reconstruct the silver nanoparticle in 3-D, detailing how all its 784 atoms were arranged.
“Up until now, only the rough outlines of nanoparticles could be illustrated using many images from different perspectives,” Rossell explains in an EMPA news release.
This sort of nanoparticle characterization could help determine which atomic configurations are best suited to various applications, like medical devices, drug transport systems and more. It could even illuminate how to use nanoparticles to mimic viruses or deliver vaccines. Incidentally, two separate teams announced breakthroughs on both those fronts today.
Emory University researchers announced Wednesday they had built tiny in size and composition, and which induce lifelong immunity in mice. The particles are made of biodegradable polymers and activate two different parts of the innate immune system, the researchers say. They could be used with material from many different bacteria or viruses, a potential breakthrough for vaccine delivery.
Also in nanovax news, MIT researchers said Wednesday they had developed a new for diseases like HIV and malaria. The particles, which are fatty spheres, can carry synthetic versions of virus proteins that elicit a strong immune response, according to MIT News.
Now that there’s a method to take their pictures, scientists may be able to learn even more about how nanoparticles function at the atomic scale.