Nanotechnology Sparks Energy Storage on Paper and Cloth

Nanotechnology Sparks Energy Storage on Paper and Cloth

  10:08:00 PM    Science Lover

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By dipping ordinary paper or fabric in a special ink infused with nanoparticles, Stanford engineer Yi Cui has found a way to cheaply and efficiently manufacture lightweight paper batteries and supercapacitors (which, like batteries, store energy, but by electrostatic rather than chemical means), as well as stretchable, conductive textiles known as "eTextiles" -- capable of storing energy while retaining the mechanical properties of ordinary paper or fabric.

While the technology is still new, Cui's team has envisioned numerous functional uses for their inventions. Homes of the future could one day be lined with energy-storing wallpaper. Gadget lovers would be able to charge their portable appliances on the go, simply plugging them into an outlet woven into their T-shirts. Energy textiles might also be used to create moving-display apparel, reactive high-performance sportswear and wearable power for a soldier's battle gear.

The key ingredients in developing these high-tech products are not visible to the human eye. Nanostructures, which can be assembled in patterns that allow them to transport electricity, may provide the solutions to a number of problems encountered with electrical storage devices currently available on the market.

The type of nanoparticle used in the Cui group's experimental devices varies according to the intended function of the product -- lithium cobalt oxide is a common compound used for batteries, while single-walled carbon nanotubes, or SWNTs, are used for supercapacitors.

Cui, an assistant professor of materials science and engineering at Stanford, leads a research group that investigates new applications of nanoscale materials. The objective, said Cui, is not only to supply answers to theoretical inquiries but also to pursue projects with practical value. Recently, his team has focused on ways to integrate nanotechnology into the realm of energy development.

"Energy storage is a pretty old research field," said Cui. "Supercapacitors, batteries -- those things are old. How do you really make a revolutionary impact in this field? It requires quite a dramatic difference of thinking."

While electrical energy storage devices have come a long way since Alessandro Volta debuted the world's first electrical cell in 1800, the technology is facing yet another revolution. Current methods of manufacturing energy storage devices can be capital intensive and environmentally hazardous, and the end products have noticeable performance constraints -- conventional lithium ion batteries have a limited storage capacity and are costly to manufacture, while traditional capacitors provide high power but at the expense of energy storage capacity.

With a little help from new science, the batteries of the future may not look anything like the bulky metal units we've grown accustomed to. Nanotechnology is favored as a remedy both for its economic appeal and its capability to improve energy performance in devices that integrate it. Replacing the carbon (graphite) anodes found in lithium ion batteries with anodes of silicon nanowires, for example, has the potential to increase their storage capacity by 10 times, according to experiments conducted by Cui's team.

Silicon had previously been recognized as a favorable anode material because it can hold a larger amount of lithium than carbon. But applications of silicon were limited by its inability to sustain physical stress -- namely, the fourfold volume increase that silicon undergoes when lithium ions attach themselves to a silicon anode in the process of charging a battery, as well as the shrinkage that occurs when lithium ions are drawn out as it discharges. The result was that silicon structures would disintegrate, causing anodes of this material to lose much if not all of their storage capacity.

Cui and collaborators demonstrated in previous publications in Nature, Nanotechnology and Nano Letters that the use of silicon nanowire battery electrodes, mechanically capable of withstanding the absorption and discharge of lithium ions, was one way to sidestep the problem.

The findings hold promise for the development of rechargeable lithium batteries offering a longer life cycle and higher energy capacity than their contemporaries. Silicon nanowire technology may one day find a home in electric cars, portable electronic devices and implantable medical appliances.

Cui now hopes to direct his research toward studying both the "hard science" behind the electrical properties of nanomaterials and designing real-world applications.

"This is the right time to really see what we learn from nanoscience and do practical applications that are extremely promising," said Cui. "The beauty of this is, it combines the lowest cost technology that you can find to the highest tech nanotechnology to produce something great. I think this is a very exciting idea … a huge impact for society."

The Cui group's latest research on energy storage devices was detailed in papers published in the online editions of the Proceedings of the National Academy of Sciences in December 2009 ("Highly Conductive Paper for Energy-Storage Devices") and Nano Letters in January 2010 ("Stretchable, Porous and Conductive Energy Textiles").

Cui's presented his talk at the symposium "Nanotechnology: Will Nanomaterials Revolutionize Energy Applications?" at the San Diego Convention Center.

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Functioning Synapse Created Using Carbon Nanotubes: Devices Might Be Used in Brain Prostheses or Synthetic Brains

Functioning Synapse Created Using Carbon Nanotubes: Devices Might Be Used in Brain Prostheses or Synthetic Brains

  1:38:00 AM    Science Lover

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Engineering researchers the University of Southern California have made a significant breakthrough in the use of nanotechnologies for the construction of a synthetic brain. They have built a carbon nanotube synapse circuit whose behavior in tests reproduces the function of a neuron, the building block of the brain.

This image shows nanotubes used in synthetic 
synapse and apparatus used to create them. 
(Credit: USC Viterbi School of Engineering)

The team, which was led by Professor Alice Parker and Professor Chongwu Zhou in the USC Viterbi School of Engineering Ming Hsieh Department of Electrical Engineering, used an interdisciplinary approach combining circuit design with nanotechnology to address the complex problem of capturing brain function.

In a paper published in the proceedings of the IEEE/NIH 2011 Life Science Systems and Applications Workshop in April 2011, the Viterbi team detailed how they were able to use carbon nanotubes to create a synapse.

Carbon nanotubes are molecular carbon structures that are extremely small, with a diameter a million times smaller than a pencil point. These nanotubes can be used in electronic circuits, acting as metallic conductors or semiconductors.

"This is a necessary first step in the process," said Parker, who began the looking at the possibility of developing a synthetic brain in 2006. "We wanted to answer the question: Can you build a circuit that would act like a neuron? The next step is even more complex. How can we build structures out of these circuits that mimic the function of the brain, which has 100 billion neurons and 10,000 synapses per neuron?"

Parker emphasized that the actual development of a synthetic brain, or even a functional brain area is decades away, and she said the next hurdle for the research centers on reproducing brain plasticity in the circuits.

The human brain continually produces new neurons, makes new connections and adapts throughout life, and creating this process through analog circuits will be a monumental task, according to Parker.

She believes the ongoing research of understanding the process of human intelligence could have long-term implications for everything from developing prosthetic nanotechnology that would heal traumatic brain injuries to developing intelligent, safe cars that would protect drivers in bold new ways.

For Jonathan Joshi, a USC Viterbi Ph.D. student who is a co-author of the paper, the interdisciplinary approach to the problem was key to the initial progress. Joshi said that working with Zhou and his group of nanotechnology researchers provided the ideal dynamic of circuit technology and nanotechnology.

"The interdisciplinary approach is the only approach that will lead to a solution. We need more than one type of engineer working on this solution," said Joshi. "We should constantly be in search of new technologies to solve this problem."

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U of T researchers build an antenna for light

U of T researchers build an antenna for light

  9:53:00 AM    Science Lover

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University of Toronto researchers have derived inspiration from the photosynthetic apparatus in plants to engineer a new generation of nanomaterials that control and direct the energy absorbed from light.

Their findings are reported in a forthcoming issue of Nature Nanotechnology, which will be released on July 10, 2011.

The U of T researchers, led by Professors Shana Kelley and Ted Sargent, report the construction of what they term "artificial molecules."

"Nanotechnologists have for many years been captivated by quantum dots – particles of semiconductor that can absorb and emit light efficiently, and at custom-chosen wavelengths," explained co-author Kelley, a Professor at the Leslie Dan Faculty of Pharmacy, the Department of Biochemistry in the Faculty of Medicine, and the Department of Chemistry in the Faculty of Arts & Science. "What the community has lacked – until now – is a strategy to build higher-order structures, or complexes, out of multiple different types of quantum dots. This discovery fills that gap."

The team combined its expertise in DNA and in semiconductors to invent a generalized strategy to bind certain classes of nanoparticles to one another.

"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," said Sargent, a Professor in The Edward S. Rogers Sr. Department of Electrical & Computer Engineering at the University of Toronto, who is also the Canada Research Chair in Nanotechnology. "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."



Traditional antennas increase the amount of an electromagnetic wave – such as a radio frequency – that is absorbed, and then funnel that energy to a circuit. The U of T nanoantennas instead increased the amount of light that is absorbed and funneled it to a single site within their molecule-like complexes. This concept is already used in nature in light harvesting antennas, constituents of leaves that make photosynthesis efficient. "Like the antennas in radios and mobile phones, our complexes captured dispersed energy and concentrated it to a desired location. Like the light harvesting antennas in the leaves of a tree, our complexes do so using wavelengths found in sunlight," explained Sargent.

"Professors Kelley and Sargent have invented a novel class of materials with entirely new properties. Their insight and innovative research demonstrates why the University of Toronto leads in the field of nanotechnology," said Professor Henry Mann, Dean of the Leslie Dan Faculty of Pharmacy.

"This is a terrific piece of work that demonstrates our growing ability to assemble precise structures, to tailor their properties, and to build in the capability to control these properties using external stimuli," noted Paul S. Weiss, Fred Kavli Chair in NanoSystems Sciences at UCLA and Director of the California NanoSystems Institute.

Kelley explained that the concept published in today's Nature Nanotechnology paper is a broad one that goes beyond light antennas alone.

"What this work shows is that our capacity to manipulate materials at the nanoscale is limited only by human imagination. If semiconductor quantum dots are artificial atoms, then we have rationally synthesized artificial molecules from these versatile building blocks."

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Explanatory ‘Nano Song’ becomes mega-hit on Youtube

Explanatory ‘Nano Song’ becomes mega-hit on Youtube

  12:23:00 PM    Science Lover

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Vocalist Glory Liu poses with a muppet

How would you explain “nanotechnology” to a science novice? A group of US-based students from the University of California, Berkeley, have answered this call with a pint-sized video - part Sound of Music, part Muppets, part science class. Its online reception, though, has been anything but small!

The Nano Song features music and lyrics by 27-year-old Ryan Miyakawa, a pianist-composer and engineering graduate student. Glory Liu - a classics and political economy major with three years of classical music training - lends voice to the lyrics, cheerfully explaining nanotechnology to a band of puppets: “A million nanometres that are lined up in a row/Are just about as long as a single flake of snow….”

Image via CrunchBase

The piece went online on February 22, when the group submitted it to the American Chemical Society (ACS), as part of its competition to explain nanotechnology in no more than three minutes.

Fame wasted no time. By early March, The Nano Song had spread virally, with mentions by PhysOrg.com, Scientific American, WIRED, and boingboing. When YouTube featured the video on its home page, it quickly racked up over 3,00,000 hits, along with a mountain of comments from viewers, like: “‘Nano Song’ is rocking the globe!”

“I turned comments off after the first 200,” says Miyakawa.

Nanotechnology is a hot topic in science and engineering, but experts in the field have trouble explaining it to the uninitiated, he notes.

“Therefore, I wanted to do something fun that would be acceptable to the public,” he says.

To Miyakawa, a silly yet edifying song seemed to be in order. He spent a day composing a tune - using music software to lay down a big orchestral sound - and writing lyrics with across-the-board appeal.

The refrain goes: “Nano, nana, nano/ What a wonderful surprise/That ordinary is extraordinary/When you make it nano size!”

Turning the snappy ‘Nano Song’ into a video was challenging; complete with its troupe of students and alumni, who built and manipulated puppets for the shoot.

The Nano Song is currently the top-rated and most-viewed contest submission, with more than 12,000 views on the ACS site.

To see the video itself, ‘behind the scenes’ photos of its making; or to download an MP3 of the song, visit www.nanosong.com.
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More data storage? Here's how to fit 1,000 terabytes on a DVD

More data storage? Here's how to fit 1,000 terabytes on a DVD

  1:17:00 AM    Science Lover

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We live in a world where digital information is exploding. Some 90% of the world's data was generated in the past two years. The obvious question is: how can we store it all?

Using nanotechnology, researchers have developed a technique to increase the data storage capacity of a DVD from a measly 4.7GB to 1,000TB. Credit: Nature Communications

In Nature Communications today, we, along with Richard Evans from CSIRO, show how we developed a new technique to enable the data capacity of a single DVD to increase from 4.7 gigabytes up to one petabyte (1,000 terabytes). This is equivalent of 10.6 years of compressed high-definition video or 50,000 full high-definition movies.

So how did we manage to achieve such a huge boost in data storage? First, we need to understand how data is stored on optical discs such as CDs and DVDs.

The basics of digital storage

Although optical discs are used to carry software, films, games, and private data, and have great advantages over other recording media in terms of cost, longevity and reliability, their low data storage capacity is their major limiting factor.

The operation of optical data storage is rather simple. When you burn a CD, for example, the information is transformed to strings of binary digits (0s and 1s, also called bits). Each bit is then laser "burned" into the disc, using a single beam of light, in the form of dots.

The storage capacity of optical discs is mainly limited by the physical dimensions of the dots. But as there's a limit to the size of the disc as well as the size of the dots, many current methods of data storage, such as DVDs and Blu-ray discs, continue to have low level storage density.

To get around this, we had to look at light's fundamental laws.
On the basis of this law, the diameter of a spot of light, obtained by focusing a light beam through a lens, cannot be smaller than half its wavelength – around 500 nanometres (500 billionths of a metre) for visible light.

And while this law plays a huge role in modern optical microscopy, it also sets up a barrier for any efforts from researchers to produce extremely small dots – in the nanometre region – to use as binary bits.

In our study, we showed how to break this fundamental limit by using a two-light-beam method, with different colours, for recording onto discs instead of the conventional single-light-beam method.

Both beams must abide by Abbe's law, so they cannot produce smaller dots individually. But we gave the two beams different functions:

• The first beam (red, in the figure right) has a round shape, and is used to activate the recording. We called it the writing beam
• The second beam – the purple donut-shape – plays an anti-recording function, inhibiting the function of the writing beam

The two beams were then overlapped. As the second beam cancelled out the first in its donut ring, the recording process was tightly confined to the centre of the writing beam.

This new technique produces an effective focal spot of nine nanometres – or one ten thousandth the diameter of a human hair.

The technique, in practical terms

Our work will greatly impact the development of super-compact devices as well as nanoscience and nanotechnology research.

The exceptional penetration feature of light beams allow for 3D recording or fabrication, which can dramatically increase the data storage – the number of dots – on a single optical device.

The technique is also cost-effective and portable, as only conventional optical and laser elements are used, and allows for the development of optical data storage with long life and low energy consumption, which could be an ideal platform for a Big Data centre.

As the rate of information generated worldwide continues to accelerate, the aim of more storage capacity in compact devices will continue. Our breakthrough has put that target within our reach.

 

More information: www.nature.com/ncomms/2013/130619/ncomms3061/full/ncomms3061.html 

 

Story from: http://phys.org/news/2013-06-storage-terabytes-dvd.html#ajTabs

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New Nanolaser Key To Future Optical Computers And Technologies

New Nanolaser Key To Future Optical Computers And Technologies

  7:59:00 PM    Science Lover

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Researchers have created the tiniest laser since its invention nearly 50 years ago, paving the way for a host of innovations, including superfast computers that use light instead of electrons to process information, advanced sensors and imaging.

Researchers have created the tiniest laser since its invention nearly 50 years ago. Because the new device, called a "spaser," is the first of its kind to emit visible light, it represents a critical component for possible future technologies based on "nanophotonic" circuitry. The color diagram (a) shows the nanolaser's design: a gold core surrounded by a glasslike shell filled with green dye. Scanning electron microscope images (b and c) show that the gold core and the thickness of the silica shell were about 14 nanometers and 15 nanometers, respectively. A simulation of the SPASER (d) shows the device emitting visible light with a wavelength of 525 nanometers. (Credit: Birck Nanotechnology Center, Purdue University)

Because the new device, called a "spaser," is the first of its kind to emit visible light, it represents a critical component for possible future technologies based on "nanophotonic" circuitry, said Vladimir Shalaev, the Robert and Anne Burnett Professor of Electrical and Computer Engineering at Purdue University.

Such circuits will require a laser-light source, but current lasers can't be made small enough to integrate them into electronic chips. Now researchers have overcome this obstacle, harnessing clouds of electrons called "surface plasmons," instead of the photons that make up light, to create the tiny spasers.

Findings are detailed in a paper appearing online in the journal Nature, reporting on work conducted by researchers at Purdue, Norfolk State University and Cornell University.

Nanophotonics may usher in a host of radical advances, including powerful "hyperlenses" resulting in sensors and microscopes 10 times more powerful than today's and able to see objects as small as DNA; computers and consumer electronics that use light instead of electronic signals to process information; and more efficient solar collectors.

"Here, we have demonstrated the feasibility of the most critical component - the nanolaser - essential for nanophotonics to become a practical technology," Shalaev said.

The "spaser-based nanolasers" created in the research were spheres 44 nanometers, or billionths of a meter, in diameter - more than 1 million could fit inside a red blood cell. The spheres were fabricated at Cornell, with Norfolk State and Purdue performing the optical characterization needed to determine whether the devices behave as lasers.

The findings confirm work by physicists David Bergman at Tel Aviv University and Mark Stockman at Georgia State University, who first proposed the spaser concept in 2003.

"This work represents an important milestone that may prove to be the start of a revolution in nanophotonics, with applications in imaging and sensing at a scale that is much smaller than the wavelength of visible light," said Timothy D. Sands, the Mary Jo and Robert L. Kirk Director of the Birck Nanotechnology Center in Purdue's Discovery Park.

The spasers contain a gold core surrounded by a glasslike shell filled with green dye. When a light was shined on the spheres, plasmons generated by the gold core were amplified by the dye. The plasmons were then converted to photons of visible light, which was emitted as a laser.

Spaser stands for surface plasmon amplification by stimulated emission of radiation. To act like lasers, they require a "feedback system" that causes the surface plasmons to oscillate back and forth so that they gain power and can be emitted as light. Conventional lasers are limited in how small they can be made because this feedback component for photons, called an optical resonator, must be at least half the size of the wavelength of laser light.

The researchers, however, have overcome this hurdle by using not photons but surface plasmons, which enabled them to create a resonator 44 nanometers in diameter, or less than one-tenth the size of the 530-nanometer wavelength emitted by the spaser.

"It's fitting that we have realized a breakthrough in laser technology as we are getting ready to celebrate the 50th anniversary of the invention of the laser," Shalaev said.

The first working laser was demonstrated in 1960.

The research was conducted by Norfolk State researchers Mikhail A. Noginov, Guohua Zhu and Akeisha M. Belgrave; Purdue researchers Reuben M. Bakker, Shalaev and Evgenii E. Narimanov; and Cornell researchers Samantha Stout, Erik Herz, Teeraporn Suteewong and Ulrich B. Wiesner.

Future work may involve creating a spaser-based nanolaser that uses an electrical source instead of a light source, which would make them more practical for computer and electronics applications.

The work was funded by the National Science Foundation and U.S. Army Research Office and is affiliated with the Birck Nanotechnology Center, the Center for Materials Research at Norfolk State, and Cornell's Materials Science and Engineering Department.

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Spontaneous Assembly: A New Look At How Proteins Assemble And Organize Themselves Into Complex Patterns

Spontaneous Assembly: A New Look At How Proteins Assemble And Organize Themselves Into Complex Patterns

  9:28:00 PM    Science Lover

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Self-assembling and self-organizing systems are the Holy Grails of nanotechnology, but nature has been producing such systems for millions of years. A team of scientists has taken a unique look at how thousands of bacterial membrane proteins are able to assemble into clusters that direct cell movement to select chemicals in their environment. Their results provide valuable insight into how complex periodic patterns in biological systems can be generated and repaired.

PALM is an an ultrahigh-precision visible light microscopy
technique that enables scientists to photo-actively fluoresce
and image individual proteins. This PALM composite of an
E.coli bacterial cell shows the organization of proteins in
the chemotaxis signaling network.
(Credit: Image courtesy of DOE/Lawrence Berkeley National Laboratory)

Researchers with Berkeley Lab, the University of California (UC) Berkeley, the Howard Hughes Medical Institute, and Princeton University, used an ultrahigh-precision visible light microscopy technique called PALM - for Photo-Activated Localization Microscopy - to show that the chemotaxis network of signaling proteins in E.coli bacteria is able to spontaneously form from clusters of proteins without being actively distributed or attached to specific locations in cells. This simple organizational mechanism - dubbed “stochastic self-assembly” - is related to the self-organizing patterns first described in 1952 by the British computer scientist Alan Turing.

“It is not widely appreciated that complex periodic patterns can spontaneously emerge from simple mechanisms, but that is probably what is happening here,” said Jan Liphardt, the biophysicist who led this research.

Liphardt holds a joint appointment with Berkeley Lab’s Physical Biosciences Division and UC Berkeley’s Physics Department. He is the principal author of a paper now available PLoS Biology. Co-authoring the paper with Liphardt were Derek Greenfield, Ann McEvoy, Hari Shroff, Gavin Crooks, Ned Wingreen and Eric Betzig.

Key to a cell’s survival is the manner in which its critical components - proteins, lipids, nucleic acids, etc. - are arranged. For cells to thrive, the organization of these components must be optimized for their respective activities and also reproducible for succeeding generations of cells. Eukaryotic cells feature distinct subcellular structures, such as membrane-bound organelles and protein transport systems, whose complex organization is readily apparent. However, there is also complex spatial organization to be found within prokaryotic cells, such as rod-shaped bacteria like E. coli.

“It has remained somewhat mysterious how bacteria are able to organize and spatially segregate their interiors and membranes,” said Liphardt. “Two cells which are biochemically identical can have very different behaviors, depending upon their spatial organization. With new technologies such as PALM, we are able to see exactly how cells are organized and relate spatial organization with biological function.”

PALM and the Chemotaxis Network

In the PALM technique, target proteins are labeled with tags that fluoresce when activated by weak ultraviolet light. By keeping the intensity of this light sufficiently low, researchers can photoactivate individual proteins.

“Since individual proteins are imaged one at a time, we can localize and count them, and then computationally assemble the locations of all proteins into a composite, high-precision image,” said Liphardt. “With other technologies, we have to choose between observing large clusters or observing single proteins. With PALM, we can examine a cell and see single proteins, protein dimers, and so forth, all the way up to large clusters containing thousands of proteins. This enables us to see the relative organization of individual proteins within clusters and at the same time see how clusters are arranged with respect to one-another.”

Liphardt and his colleagues applied the PALM technique to the E.coli chemotaxis network of signaling proteins, which direct the movement of the bacteria towards or away from sugars, amino acids, and many other soluble molecules in response to environmental cues. The E.coli chemotaxis network is one of the best-understood of all biological signaling systems and is a model for studying bacterial spatial organization because its components display a nonrandom, periodic distribution in the cell membrane.

“Chemotaxis proteins cluster into large sensory complexes that localize to the poles of the bacterial cell,” Liphardt said. “We wanted to understand how these clusters form, what controls their size and density, and how the cellular location of clusters is robustly maintained in growing and dividing cells.”

Using PALM, Liphardt and his colleagues mapped the cellular locations of three proteins central to the chemotaxis signaling network - Tar, CheY and CheW - with a mean precision of 15 nanometers. They found that cluster sizes were distributed with no one size being “characteristic.” For example, a third of the Tar proteins were part of smaller lateral clusters and not of the large polar clusters. Analysis of the relative cellular locations of more than one million individual proteins from 326 cells determined that they are not actively distributed or attached to specific locations in cells, as had been hypothesized.

“Instead,” said Liphardt, “random lateral protein diffusion and protein-protein interactions are probably sufficient to generate the observed complex, ordered patterns. This simple stochastic self-assembly mechanism, which can create and maintain periodic structures in biological membranes without direct cytoskeletal involvement or active transport, may prove to be widespread in both prokaryotic and eukaryotic cells.”

Liphardt and his research group are now applying PALM to signaling complexes in eukaryotic membranes to see how widespread is stochastic self-assembly in nature. Given that biological systems are nature’s version of nanotechnology, the demonstration that stochastic self-assembly is capable of organizing thousands of proteins into complex and reproducible patterns holds promise for a wide range of applications in nanotechnology, including the fabrication of nanodevices and the development of nanoelectronic circuits.

This work was funded by the U.S. Department of Energy’s Office of Science, Energy Biosciences Program, the Sloan and Searle Foundations, and National Institutes of Health grants.

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'Transformation Optics' May Yield Invisbility

'Transformation Optics' May Yield Invisbility

  1:29:00 PM    Science Lover

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Researchers have overcome a fundamental obstacle in using new "metamaterials" for radical advances in optical technologies, including ultra-powerful microscopes and computers and a possible invisibility cloak.

This illustration shows the structure of a new device 
created by Purdue researchers to overcome a 
fundamental obstacle in using new "metamaterials" 
for radical advances in optical technologies, including 
ultrapowerful microscopes and computers and a 
possible invisibility cloak. The material developed by 
the researchers is a perforated, fishnet-like film made 
of repeating layers of silver and aluminum oxide. The 
researchers etched away a portion of the aluminum 
oxide between silver layers and replaced it with a 
"gain medium" to amplify light. (Credit: Birck 
Nanotechnology Center, Purdue University)

The metamaterials have been plagued by a major limitation: too much light is "lost," or absorbed by metals such as silver and gold contained in the metamaterials, making them impractical for optical devices.

However, a Purdue University team has solved this hurdle, culminating three years of research based at the Birck Nanotechnology Center at the university's Discovery Park.

"This finding is fundamental to the whole field of metamaterials," said Vladimir M. Shalaev, Purdue's Robert and Anne Burnett Professor of Electrical and Computer Engineering. "We showed that, in principle, it's feasible to conquer losses and develop these materials for many applications."

Research findings are detailed in a paper appearing on Aug. 5 in the journal Nature.

The material developed by Purdue researchers is made of a fishnet-like film containing holes about 100 nanometers in diameter and repeating layers of silver and aluminum oxide. The researchers etched away a portion of the aluminum oxide between silver layers and replaced it with a "gain medium" formed by a colored dye that can amplify light.

Other researchers have applied various gain media to the top of the fishnet film, but that approach does not produce sufficient amplification to overcome losses, Shalaev said.

Instead, the Purdue team found a way to place the dye between the two fishnet layers of silver, where the "local field" of light is far stronger than on the surface of the film, causing the gain medium to work 50 times more efficiently.

The approach was first developed by former Purdue doctoral student Hsiao-Kuan Yuan, now at Intel Corp., and it was further developed and applied by doctoral student Shumin Xiao.

Unlike natural materials, metamaterials are able to reduce the "index of refraction" to less than one or less than zero. Refraction occurs as electromagnetic waves, including light, bend when passing from one material into another. It causes the bent-stick-in-water effect, which occurs when a stick placed in a glass of water appears bent when viewed from the outside.

Being able to create materials with an index of refraction that's negative or between one and zero promises a range of potential breakthroughs in a new field called transformation optics. Possible applications include a "planar hyperlens" that could make optical microscopes 10 times more powerful and able to see objects as small as DNA; advanced sensors; new types of "light concentrators" for more efficient solar collectors; computers and consumer electronics that use light instead of electronic signals to process information; and a cloak of invisibility.

Excitement about metamaterials has been tempered by the fact that too much light is absorbed by the materials. However, the new approach can dramatically reduce the "absorption coefficient," or how much light and energy is lost, and might amplify the incident light so that the metamaterial becomes "active," Shalaev said.

"What's really important is that the absorption coefficient can be as small as only one-millionth of what it was before using our approach," Shalaev said. "We can even have amplification of light instead of its absorption. Here, for the first time, we showed that metamaterials can have a negative refractive index and amplify light."

The Nature paper was written by Xiao, senior research scientist Vladimir P. Drachev, principal research scientist Alexander V. Kildishev, doctoral student Xingjie Ni, postdoctoral fellow Uday K. Chettiar, Yuan, and Shalaev.

Fabricating the material was a major challenge, Shalaev said.

First, the researchers had to learn how to precisely remove as much as possible of the aluminum oxide layer in order to vacate space for dye without causing a collapse of the structure.

"You remove it almost completely but leave a little bit to act as pillars to support the structure, and then you spin coat the dye-doped polymer inside the structure," he said.

The researchers also had to devise a way to deposit just the right amount of dye mixed with an epoxy between the silver layers of the perforated film.

"You can't deposit too much dye and epoxy, which have a positive refractive index, but only a thin layer about 50 nanometers thick, or you lose the negative refraction," Shalaev said.

Future work may involve creating a technology that uses an electrical source instead of a light source, like semiconductor lasers now in use, which would make them more practical for computer and electronics applications.

The work was funded by the U.S. Army Research Office and the National Science Foundation.

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15,000 Beams of Light: Pens That Write With Light

15,000 Beams of Light: Pens That Write With Light

  11:17:00 PM    Science Lover

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One Chicago skyline is dazzling enough. Now imagine 15,000 of them.

Using beam-pen lithography, Northwestern 
researchers patterned 15,000 replicas of the 
Chicago skyline simultaneously over square 
centimeters of space in about half an hour. 
(Credit: Image courtesy of Northwestern University)

A Northwestern University research team has done just that -- drawing 15,000 identical skylines with tiny beams of light using an innovative nanofabrication technology called beam-pen lithography (BPL).

Details of the new method, which could do for nanofabrication what the desktop printer has done for printing and information transfer, will be published Aug. 1 by the journal Nature Nanotechnology.

The Northwestern technology offers a means to rapidly and inexpensively make and prototype circuits, optoelectronics and medical diagnostics and promises many other applications in the electronics, photonics and life sciences industries.

"It's all about miniaturization," said Chad A. Mirkin, George B. Rathmann Professor of Chemistry in the Weinberg College of Arts and Sciences and director of Northwestern's International Institute for Nanotechnology. "Rapid and large-scale transfer of information drives the world. But conventional micro- and nanofabrication tools for making structures are very expensive. We are trying to change that with this new approach to photolithography and nanopatterning."

Using beam-pen lithography, the researchers patterned 15,000 replicas of the Chicago skyline (featuring the Willis Tower and the John Hancock Center) simultaneously in about half an hour. Fifteen thousand tiny pens deposit the skylines over square centimeters of space. Conventional nanopatterning technologies, such as electron-beam lithography, allow one to make similarly small structures but are inherently low throughput and do not allow one to do large-area nanofabrication.

Each skyline pattern is made up of 182 dots, with each dot approximately 500 nanometers in diameter, like each pen tip. The time of light exposure for each dot was 20 seconds. The current method allows researchers to make structures as small as 150 nanometers, but refinements of the pen architecture likely will increase resolution to below 100 nanometers. (Although not reported in the paper, the researchers have created an array of 11 million pens in an area only a few centimeters square.)

Beam-pen lithography is the third type of "pen" in Mirkin's nanofabrication arsenal. He developed polymer-pen lithography (PPL) in 2008 and Dip-Pen Nanolithography (DPN) in 1999, both of which deliver chemical materials to a surface and have since been commercialized into research-grade nanofabrication tools that are now used in 23 countries around the world.

Like PPL, beam-pen lithography uses an array of tiny pens made of a polymer to print patterns over large areas with nanoscopic through macroscopic resolution. But instead of using an "ink" of molecules, BPL draws patterns using light on a light-sensitive material.

Each pen is in the shape of a pyramid, with the point as its tip. The researchers coat the pyramids with a very thin layer of gold and then remove a tiny amount of gold from each tip. The large open tops of the pyramids (the back side of the array) are exposed to light, and the gold-plated pyramids channel the light to the tips. A fine beam of light comes from each tip, where the gold was removed, exposing the light-sensitive material at each point. This allows the researchers to print patterns with great precision and ease.

"Another advantage is that we don't have to use all the pens at once -- we can shut some off and turn on others," said Mirkin, who also is professor of medicine and professor of materials science and engineering. "Because the tops of the pyramids are on the microscale, we can control each individual tip."

Beam-pen lithography could lead to the development of a desktop printer of sorts for nanofabrication, giving individual researchers a great deal of control of their work.

"Such an instrument would allow researchers at universities and in the electronics industry around the world to rapidly prototype -- and possibly produce -- high-resolution electronic devices and systems right in the lab," Mirkin said. "They want to test their patterns immediately, not have to wait for a third-party to produce prototypes, which is what happens now."

In addition to Mirkin, other authors of the paper are Fengwei Huo, Gengfeng Zheng, Xing Liao, Louise R. Giam, Jinan Chai, Xiaodong Chen and Wooyoung Shim, all from Northwestern.

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Etch-a-sketch with superconductors

Etch-a-sketch with superconductors

  10:26:00 AM    Science Lover

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Reporting in Nature Materials this week, researchers from the London Centre for Nanotechnology and the Physics Department of Sapienza University of Rome have discovered a technique to 'draw' superconducting shapes using an X-ray beam. This ability to create and control tiny superconducting structures has implications for a completely new generation of electronic devices.

In future, X-ray beams could be used to write superconducting circuits, such as those depicted in the image. Here, solid lines indicate electrical connections while semicircles denote superconducting junctions, whose states are indicated by red arrows. Credit: UCL Press Office

Superconductivity is a special state where a material conducts electricity with no resistance, meaning absolutely zero energy is wasted.

The research group has shown that they can manipulate regions of high temperature superconductivity, in a particular material which combines oxygen, copper and a heavier, 'rare earth' element called lanthanum. Illuminating with X-rays causes a small scale re-arrangement of the oxygen atoms in the material, resulting in high temperature superconductivity, of the type originally discovered for such materials 25 years ago by IBM scientists. The X-ray beam is then used like a pen to draw shapes in two dimensions.

A well as being able to write superconductors with dimensions much smaller than the width of a human hair, the group is able to erase those structures by applying heat treatments. They now have the tools to write and erase with high precision, using just a few simple steps and without the chemicals ordinarily used in device fabrication. This ability to re-arrange the underlying structure of a material has wider applications to similar compounds containing metal atoms and oxygen, ranging from fuel cells to catalysts.



Prof. Aeppli, Director of the London Centre for Nanotechnology and the UCL investigator on the project, said: "Our validation of a one-step, chemical-free technique to generate superconductors opens up exciting new possibilities for electronic devices, particularly in re-writing superconducting logic circuits. Of profound importance is the key to solving the notorious 'travelling salesman problem', which underlies many of the world's great computational challenges. We want to create computers on demand to solve this problem, with applications from genetics to logistics. A discovery like this means a paradigm shift in computing technology is one step closer."

Prof Bianconi, the leader of the team from Sapienza, added: "It is amazing that in a few simple steps, we can now add superconducting 'intelligence' directly to a material consisting mainly of the common elements copper and oxygen."

More information: The X-ray experiments were performed at the Elettra (Trieste) synchrotron radiation facility. The work is published in Nature Materials, 21 August 2011 (doi:1038/nmat3088) and follows on from previous discovery of fractal-like structures in superconductors (doi:10.1038/nature09260).

Provided by University College London

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Paper, Nanotube Ink, Wires: Instant Battery

Paper, Nanotube Ink, Wires: Instant Battery

  10:15:00 AM    Science Lover

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Stanford scientists are harnessing nanotechnology to quickly produce ultra-lightweight, bendable batteries and supercapacitors in the form of everyday paper.

Bing Hu, a post-doctoral fellow, prepares a small square of ordinary paper to with an ink that will deposit nanotubes on the surface that can then be charged with energy to create a battery. (Credit: L.A. Cicero)

Simply coating a sheet of paper with ink made of carbon nanotubes and silver nanowires makes a highly conductive storage device, said Yi Cui, assistant professor of materials science and engineering.

"Society really needs a low-cost, high-performance energy storage device, such as batteries and simple supercapacitors," he said.

Like batteries, capacitors hold an electric charge, but for a shorter period of time. However, capacitors can store and discharge electricity much more rapidly than a battery.

Cui's work is reported in the paper "Highly Conductive Paper for Energy Storage Devices," published online in the Proceedings of the National Academy of Sciences.

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New Nanoparticles Could Lead To End Of Chemotherapy

New Nanoparticles Could Lead To End Of Chemotherapy

  9:56:00 PM    Science Lover

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Nanoparticles specially engineered by University of Central Florida Assistant Professor J. Manuel Perez and his colleagues could someday target and destroy tumors, sparing patients from toxic, whole-body chemotherapies.

Dr. Manuel Perez and his team have been investigating
the use of nanoparticles for medicine for years.
(Credit: Jacque Brund)

Perez and his team used a drug called Taxol for their cell culture studies, recently published in the journal Small, because it is one of the most widely used chemotherapeutic drugs. Taxol normally causes many negative side effects because it travels throughout the body and damages healthy tissue as well as cancer cells.

The Taxol-carrying nanoparticles engineered in Perez's laboratory are modified so they carry the drug only to the cancer cells, allowing targeted cancer treatment without harming healthy cells. This is achieved by attaching a vitamin (folic acid) derivative that cancer cells like to consume in high amounts.

Because the nanoparticles also carry a fluorescent dye and an iron oxide magnetic core, their locations within the cells and the body can be seen by optical imaging and magnetic resonance imaging (MRI). That allows a physician to see how the tumor is responding to the treatment.

The nanoparticles also can be engineered without the drug and used as imaging (contrast) agents for cancer. If there is no cancer, the biodegradable nanoparticles will not bind to the tissue and will be eliminated by the liver. The iron oxide core will be utilized as regular iron in the body.

"What's unique about our work is that the nanoparticle has a dual role, as a diagnostic and therapeutic agent in a biodegradable and biocompatible vehicle," Perez said.

Perez has spent the past five years looking at ways nanotechnology can be used to help diagnose, image and treat cancer and infectious diseases. It's part of the quickly evolving world of nanomedicine.

The process works like this. Cancer cells in the tumor connect with the engineered nanoparticles via cell receptors that can be regarded as "doors" or "docking stations." The nanoparticles enter the cell and release their cargo of iron oxide, fluorescent dye and drugs, allowing dual imaging and treatment.

"Although the results from the cell cultures are preliminary, they are very encouraging," Perez said.

A new chemistry called "click chemistry" was utilized to attach the targeting molecule (folic acid) to the nanoparticles. This chemistry allows for the easy and specific attachment of molecules to nanoparticles without unwanted side products. It also allows for the easy attachment of other molecules to nanoparticles to specifically seek out particular tumors and other malignancies.

Perez's study builds on his prior research published in the prestigious journal Angewandte Chemie Int. Ed. His work has been partially funded by a National Institutes of Health grant and a Nanoscience Technology Center start-up fund.

"Our work is an important beginning, because it demonstrates an avenue for using nanotechnology not only to diagnose but also to treat cancer, potentially at an early stage," Perez said.

Perez, a Puerto Rico native, joined UCF in 2005. He works at UCF's NanoScience Technology Center and Chemistry Department and in the Burnett School of Biomedical Sciences in the College of Medicine. He has a Ph.D. from Boston University in Biochemistry and completed postdoctoral training at Massachusetts General Hospital, Harvard Medical School's teaching and research hospital.

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Super-Small Transistor Created: Artificial Atom Powered by Single Electrons

Super-Small Transistor Created: Artificial Atom Powered by Single Electrons

  12:59:00 AM    Science Lover

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A University of Pittsburgh-led team has created a single-electron transistor that provides a building block for new, more powerful computer memories, advanced electronic materials, and the basic components of quantum computers.

An atomic-scale depiction of the SketchSET shows 
three wires (green bars) converging on the central 
island (center green area), which can house up to 
two electrons. Electrons tunnel from one wire to 
another through the island. Conditions on the third 
wire can result in distinct conductive properties. 
(Credit: Image courtesy of University of Pittsburgh)

The researchers report in Nature Nanotechnology that the transistor's central component -- an island only 1.5 nanometers in diameter -- operates with the addition of only one or two electrons. That capability would make the transistor important to a range of computational applications, from ultradense memories to quantum processors, powerful devices that promise to solve problems so complex that all of the world's computers working together for billions of years could not crack them.

In addition, the tiny central island could be used as an artificial atom for developing new classes of artificial electronic materials, such as exotic superconductors with properties not found in natural materials, explained lead researcher Jeremy Levy, a professor of physics and astronomy in Pitt's School of Arts and Sciences. Levy worked with lead author and Pitt physics and astronomy graduate student Guanglei Cheng, as well as with Pitt physics and astronomy researchers Feng Bi, Daniela Bogorin,and Cheng Cen. The Pitt researchers worked with a team from the University of Wisconsin at Madison led by materials science and engineering professor Chang-Beom Eom, including research associates Chung Wun Bark, Jae-Wan Park, and Chad Folkman. Also part of the team were Gilberto Medeiros-Ribeiro, of HP Labs, and Pablo F. Siles, a doctoral student at the State University of Campinas in Brazil.

Levy and his colleagues named their device SketchSET, or sketch-based single-electron transistor, after a technique developed in Levy's lab in 2008 that works like a microscopic Etch A SketchTM, the drawing toy that inspired the idea. Using the sharp conducting probe of an atomic force microscope, Levy can create such electronic devices as wires and transistors of nanometer dimensions at the interface of a crystal of strontium titanate and a 1.2 nanometer thick layer of lanthanum aluminate. The electronic devices can then be erased and the interface used anew.

The SketchSET -- which is the first single-electron transistor made entirely of oxide-based materials -- consists of an island formation that can house up to two electrons. The number of electrons on the island -- which can be only zero, one, or two -- results in distinct conductive properties. Wires extending from the transistor carry additional electrons across the island.

One virtue of a single-electron transistor is its extreme sensitivity to an electric charge, Levy explained. Another property of these oxide materials is ferroelectricity, which allows the transistor to act as a solid-state memory. The ferroelectric state can, in the absence of external power, control the number of electrons on the island, which in turn can be used to represent the 1 or 0 state of a memory element. A computer memory based on this property would be able to retain information even when the processor itself is powered down, Levy said. The ferroelectric state also is expected to be sensitive to small pressure changes at nanometer scales, making this device potentially useful as a nanoscale charge and force sensor.

The research in Nature Nanotechnology also was supported in part by grants from the U.S. Defense Advanced Research Projects Agency (DARPA), the U.S. Army Research Office, the National Science Foundation, and the Fine Foundation.

Story Source:The above story is reprinted from materials provided by University of Pittsburgh.

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