David Kirkpatrick

October 19, 2010

Mass producing graphene

News from the University of Houston:

University of Houston professor taking next step with graphene research

The 2010 Nobel Prize in Physics went to the two scientists who first isolated graphene, one-atom-thick crystals of graphite. Now, a researcher with the University of Houston Cullen College of Engineering is trying to develop a method to mass-produce this revolutionary material.

Graphene has several properties that make it different from literally everything else on Earth: it is the first two-dimensional material ever developed; the world’s thinnest and strongest material; the best conductor of heat ever found; a far better conductor of electricity than copper; it is virtually transparent; and is so dense that no gas can pass through it. These properties make graphene a game changer for everything from energy storage devices to flat device displays.

Most importantly, perhaps, is graphene’s potential as a replacement for silicon in computer chips. The properties of graphene would enable the historical growth in computing power to continue for decades to come.

To realize these benefits, though, a way to create plentiful, defect-free graphene must be developed. Qingkai Yu, an assistant research professor with the college’s department of electrical and computer engineering and the university’s Center for Advanced Materials, is developing methods to mass-produce such high-quality graphene.

Yu is using a technology known as chemical vapor deposition. During this process, he heats methane to around 1000 degrees Celsius, breaking the gas down into its building blocks of carbon and hydrogen atoms. The carbon atoms then attach to a metallic surface to form graphene.

“This approach could produce cheap, high-quality graphene on a large scale,” Yu said.

Yu first demonstrated the viability of chemical vapor deposition for graphene creation two years ago in a paper in the journal Applied Physics Letters. He has since continued working to perfect this method.

Yu’s initial research would often result in several layers of graphene stacked together on a nickel surface. He subsequently discovered the effectiveness of copper for graphene creation. Copper has since been adopted by graphene researchers worldwide.

Yu’s work is not finished. The single layers of graphene he is now able to create are formed out of multiple graphene crystals that join together as they grow. The places where these crystals combine, known as the grain boundaries, are defects that limit the usefulness of graphene, particularly as a replacement for silicon-based computer chips.

Yu is attempting to create large layers of graphene that form out of a single crystal.

“You can imagine how important this sort of graphene is,” said Yu. “Semiconductors became a multibillion-dollar industry based on single-crystal silicon and graphene is called the post-silicon-era material. So single-crystal graphene is the Holy Grail for the next age of semiconductors.”

 

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Yu is conducting his research in collaboration with UH Ph.D. students Wei Wu and Zhihua Su as well as postdoctoral researcher Zhihong Liu. These efforts have been supported by the National Science Foundation, the U.S. Department of Defense, the U.S. Department of Energy, SEMATECH and the UH Center for Advanced Materials.

 

September 3, 2010

Graphene transistors hit 300 GHz

Via KurzweilAI.net — Great news, but as always I’d love to see a market-ready application come out of this research in the near future. Blogging about nanotech breakthroughs is all well and good, but it is excellent when I get the chance to blog about a real-world application of said breakthroughs.

From the link:

High-speed graphene transistors achieve world-record 300 GHz

September 3, 2010 by Editor

UCLA researchers have fabricated the fastest  graphene transistor to date, using a new fabrication process with a  nanowire as a self-aligned gate.

Self-aligned gates are a key element in modern transistors, which are semiconductor devices used to amplify and switch electronic signals.  Gates are used to switch the transistor between various states, and self-aligned gates were developed to deal with problems of misalignment encountered because of the shrinking scale of electronics.

“This new strategy overcomes two limitations previously encountered in graphene transistors,” professor of chemistry and biochemistry Xiangfeng Duan said. “First, it doesn’t produce any appreciable defects in the graphene during fabrication, so the high carrier mobility is retained. Second, by using a self-aligned approach with a nanowire as the gate, the group was able to overcome alignment difficulties previously encountered and fabricate very short-channel devices with unprecedented performance.”

These advances allowed the team to demonstrate the highest speed graphene transistors to date, with a cutoff frequency up to 300 GHz — comparable to the very best transistors from high-electron mobility materials such gallium arsenide or indium phosphide.

Graphene, a one-atom-thick layer of graphitic carbon, has great potential to make electronic devices such as radios, computers and phones faster and smaller. With the highest known carrier mobility — the speed at which electronic information is transmitted by a material — graphene is a good candidate for high-speed radio-frequency electronics. High-speed radio-frequency electronics may also find wide applications in microwave communication, imaging and radar technologies.

Funding for this research came from the National Science Foundation and the National Institutes of Health.

More info: UCLA news

August 26, 2010

Cool nanotech image — microneedles

Cool to look, even more cool when put into practice. Microneedles can deliver quantum dots into skin and should lead to new diagnosis and treatment of medical conditions such as skin cancer.

And now, the image:

Hollow microneedles open the door to new techniques for diagnosing and treating a variety of medical conditions, including skin cancer. Image reproduced by permission of the Royal Society of Chemistry.

For more on microneedles, here’s the full release.

August 23, 2010

200x fuel cell efficiency boost

The idea of a personalized energy system is very attractive. Talk about being able to go off the grid …

The release:

200-fold boost in fuel cell efficiency advances ‘personalized energy systems’

IMAGE: A new catalyst could help speed development of inexpensive home-brewed solar energy systems for powering homes and plug-in cars during the day (left) and for producing electricity from a fuel…

Click here for more information.

BOSTON, Aug. 23, 2010 — The era of personalized energy systems — in which individual homes and small businesses produce their own energy for heating, cooling and powering cars — took another step toward reality today as scientists reported discovery of a powerful new catalyst that is a key element in such a system. They described the advance, which could help free homes and businesses from dependence on the electric company and the corner gasoline station, at the 240th National Meeting of the American Chemical Society, being held here this week.

“Our goal is to make each home its own power station,” said study leader Daniel Nocera, Ph.D. “We’re working toward development of ‘personalized’ energy units that can be manufactured, distributed and installed inexpensively. There certainly are major obstacles to be overcome — existing fuel cells and solar cells must be improved, for instance. Nevertheless, one can envision villages in India and Africa not long from now purchasing an affordable basic system.”

Such a system would consist of rooftop solar energy panels to produce electricity for heating, cooking, lighting, and to charge the batteries on the homeowners’ electric cars. Surplus electricity would go to an “electrolyzer,” a device that breaks down ordinary water into its two components, hydrogen and oxygen. Both would be stored in tanks. In the dark of night, when the solar panels cease production, the system would shift gears, feeding the stored hydrogen and oxygen into a fuel cell that produces electricity (and clean drinking water as a byproduct). Such a system would produce clean electricity 24 hours a day, seven days a week — even when the sun isn’t shining.

Nocera’s report focused on the electrolyzer, which needs catalysts — materials that jumpstart chemical reactions like the ones that break water up into hydrogen and oxygen. He is with the Massachusetts Institute of Technology in Cambridge, Mass. Good catalysts already are available for the part of the electrolyzer that produces hydrogen. Lacking, however, have been inexpensive, long-lasting catalysts for the production of oxygen. The new catalyst fills that gap and boosts oxygen production by 200-fold. It eliminates the need for expensive platinum catalysts and potentially toxic chemicals used in making them.

The new catalyst has been licensed to Sun Catalytix, which envisions developing safe, super-efficient versions of the electrolyzer, suitable for homes and small businesses, within two years.

The National Science Foundation and the Chesonis Family Foundation provided funding for this study. Nocera did the research with post-doctoral researcher Mircea Dinca and doctoral candidate Yogesh Surendranath. The U.S. Department of Energy’s Advanced Research Projects Agency has recently awarded the team with a grant, which it plans to use to search for related compounds that can further increase the efficiency of its electrolyzer technology. The team hopes that nickel-borate belongs to a family of compounds that can be optimized for super-efficient, long-term energy storage technologies.

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The American Chemical Society is a non-profit organization chartered by the U.S. Congress. With more than 161,000 members, ACS is the world’s largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

Update 9/2/10 — Someone really likes this story because here’s a follow-up release from yesterday.

August 11, 2010

Better understanding graphene

Yes, graphene is something of a miracle material (hit this link for my extensive graphene blogging), and yes it’s proving to be very vexing material as well. There’s a whole lot of promise, but not so much practice because graphene is proving to be a very fickle material. Research like this from the Georgia Institute of Technology is particularly important because unlocking the secret life of graphene will allow for increasing practical applications. Better understanding will lead to better utilization.

The release:

Study of electron orbits in multilayer graphene finds unexpected energy gaps

Electron transport

IMAGE: Stacking of graphene sheets creates regions where the moiré alignment is of type AA (all atoms have neighbors in the layer below), AB (only A atoms have neighbors) or BA…

Click here for more information.

Researchers have taken one more step toward understanding the unique and often unexpected properties of graphene, a two-dimensional carbon material that has attracted interest because of its potential applications in future generations of electronic devices.

In the Aug. 8 advance online edition of the journal Nature Physics, researchers from the Georgia Institute of Technology and the National Institute of Standards and Technology (NIST) describe for the first time how the orbits of electrons are distributed spatially by magnetic fields applied to layers of epitaxial graphene.

The research team also found that these electron orbits can interact with the substrate on which the graphene is grown, creating energy gaps that affect how electron waves move through the multilayer material. These energy gaps could have implications for the designers of certain graphene-based electronic devices.

“The regular pattern of energy gaps in the graphene surface creates regions where electron transport is not allowed,” said Phillip N. First, a professor in the Georgia Tech School of Physics and one of the paper’s co-authors. “Electron waves would have to go around these regions, requiring new patterns of electron wave interference. Understanding such interference will be important for bi-layer graphene devices that have been proposed, and may be important for other lattice-matched substrates used to support graphene and graphene devices.”

In a magnetic field, an electron moves in a circular trajectory – known as a cyclotron orbit – whose radius depends on the size of the magnetic field and the energy of electron. For a constant magnetic field, that’s a little like rolling a marble around in a large bowl, First said.

“At high energy, the marble orbits high in the bowl, while for lower energies, the orbit size is smaller and lower in the bowl,” he explained. “The cyclotron orbits in graphene also depend on the electron energy and the local electron potential – corresponding to the bowl – but until now, the orbits hadn’t been imaged directly.”

Placed in a magnetic field, these orbits normally drift along lines of nearly constant electric potential. But when a graphene sample has small fluctuations in the potential, these “drift states” can become trapped at a hill or valley in the material that has closed constant potential contours. Such trapping of charge carriers is important for the quantum Hall effect, in which precisely quantized resistance results from charge conduction solely through the orbits that skip along the edges of the material.

IMAGE: This graphic shows electrons that move along an equipotential, while those that follow closed equipotentials (as in a potential-energy valley) become localized (right). The arrows denote the magnetic field,…

Click here for more information.

The study focused on one particular electron orbit: a zero-energy orbit that is unique to graphene. Because electrons are matter waves, interference within a material affects how their energy relates to the velocity of the wave – and reflected waves added to an incoming wave can combine to produce a slower composite wave. Electrons moving through the unique “chicken-wire” arrangement of carbon-carbon bonds in the graphene interfere in a way that leaves the wave velocity the same for all energy levels.

In addition to finding that energy states follow contours of constant electric potential, the researchers discovered specific areas on the graphene surface where the orbital energy of the electrons changes from one atom to the next. That creates an energy gap within isolated patches on the surface.

“By examining their distribution over the surface for different magnetic fields, we determined that the energy gap is due to a subtle interaction with the substrate, which consists of multilayer graphene grown on a silicon carbide wafer,” First explained.

In multilayer epitaxial graphene, each layer’s symmetrical sublattice is rotated slightly with respect to the next. In prior studies, researchers found that the rotations served to decouple the electronic properties of each graphene layer.

“Our findings hold the first indications of a small position-dependent interaction between the layers,” said David L. Miller, the paper’s first author and a graduate student in First’s laboratory. “This interaction occurs only when the size of a cyclotron orbit – which shrinks as the magnetic field is increased – becomes smaller than the size of the observed patches.”

The origin of the position dependent interaction is believed to be the “moiré pattern” of atomic alignments between two adjacent layers of graphene. In some regions, atoms of one layer lie atop atoms of the layer below, while in other regions, none of the atoms align with the atoms in the layer below. In still other regions, half of the atoms have neighbors in the underlayer, an instance in which the symmetry of the carbon atoms is broken and the Landau level – discrete energy level of the electrons – splits into two different energies.

Experimentally, the researchers examined a sample of epitaxial graphene grown at Georgia Tech in the laboratory of Professor Walt de Heer, using techniques developed by his research team over the past several years.

They used the tip of a custom-built scanning-tunneling microscope (STM) to probe the atomic-scale electronic structure of the graphene in a technique known as scanning tunneling spectroscopy. The tip was moved across the surface of a 100-square nanometer section of graphene, and spectroscopic data was acquired every 0.4 nanometers.

The measurements were done at 4.3 degrees Kelvin to take advantage of the fact that energy resolution is proportional to the temperature. The scanning-tunneling microscope, designed and built by Joseph Stroscio at NIST’s Center for Nanoscale Science and Technology, used a superconducting magnet to provide the magnetic fields needed to study the orbits.

According to First, the study raises a number of questions for future research, including how the energy gaps will affect electron transport properties, how the observed effects may impact proposed bi-layer graphene coherent devices – and whether the new phenomenon can be controlled.

“This study is really a stepping stone in long path to understanding the subtleties of graphene’s interesting properties,” he said. “This material is different from anything we have worked with before in electronics.”

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In addition to those already mentioned, the study also included Walt de Heer, Kevin D. Kubista, Ming Ruan, and Markus Kinderman from Georgia Tech and Gregory M. Rutter from NIST. The research was supported by the National Science Foundation, the Semiconductor Research Corporation and the W.M. Keck Foundation. Additional assistance was provided by Georgia Tech’s Materials Research Science and Engineering Center (MRSEC)

August 4, 2010

Invisibility cloak update

It’s been several months since I’ve come across any news on invisibility cloak technology, something of a pet subject around here, but here’s the very latest — findings on transformation optics.

From the second link, the release:

New findings promising for ‘transformation optics,’ cloaking

WEST LAFAYETTE, Ind. — 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.

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.

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

Hit this link for the related image (it’s just too big for this blog and I didn’t feel like doing any resizing), and here’s the accompanying caption for the image:

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. (Birck Nanotechnology Center, Purdue University)

July 3, 2010

Toward quantum computing

This news comes from the University of Maryland offering another advancement toward a quantum computer — something that is ways off yet — that involves nanotechnology.

The release:

UM Scientists Advance Quantum Computing & Energy Conversion Tech

COLLEGE PARK, Md. — Using a unique hybrid nanostructure, University of Maryland researchers have shown a new type of light-matter interaction and also demonstrated the first full quantum control of qubit spin within very tiny colloidal nanostructures (a few nanometers), thus taking a key step forward in efforts to create a quantum computer.

Published in the July 1 issue of Nature, their research builds on work by the same Maryland research team published in March in the journal Science (3-26-10). According to the authors and outside experts, the new findings further advance the promise these new nanostructures hold for quantum computing and for new, more efficient, energy generation technologies (such as photovoltaic cells), as well as for other technologies that are based on light-matter interactions like biomarkers.

“The real breakthrough is that we use a new technology from materials science to ‘shed light’ on light-matter interactions and related quantum science in ways that we believe will have important applications in many areas, particularly energy conversion and storage and quantum computing,” said lead researcher Min Ouyang, an assistant professor in the department of physics and in the university’s Maryland NanoCenter. “In fact, our team already is applying our new understanding of nanoscale light-matter interactions and advancement of precise control of nanostructures to the development of a new type of photovoltaic cell that we expect to be significantly more efficient at converting light to electricity than are current cells.”

Ouyang and the other members of the University of Maryland team — research scientist Jiatao Zhang, and students Kwan Lee and Yun Tang — have created a patent-pending process that uses chemical thermodynamics to produce, in solution, a broad range of different combination materials, each with a shell of structurally perfect mono-crystal semiconductor around a metal core. In the research published in this week’s Nature, the researchers used hybrid metal/semiconductor nanostructures developed through this process to experimentally demonstrate “tunable resonant coupling” between a plasmon (from metal core) and an exciton (from semiconductor shell), with a resulting enhancement of the Optical Stark Effect. This effect was discovered some 60 years ago in studies of the interaction between light and atoms that showed light can be applied to modify atomic quantum states.

Nanostructures, Large Advances
“Metal-semiconductor heteronanostructures have been investigated intensely in the last few years with the metallic components used as nanoscale antennas to couple light much more effectively into and out of semiconductor nanoscale, light-emitters,” said Garnett W. Bryant, leader of the Quantum Processes and Metrology Group in the Atomic Physics Division of the National Institute of Standards and Technology (NIST). “The research led Min Ouyang shows that a novel heteronanostructure with the semiconductor surrounding the metallic nanoantenna can achieve the same goals. Such structures are very simple and much easier to make than previously attempted, greatly opening up possibilities for application. Most importantly, they have demonstrated that the light/matter coupling can be manipulated to achieve coherent quantum control of the semiconductor nanoemitters, a key requirement for quantum information processing,” said Bryant, who is not involved with this research. Bryant also is a scientist in the Joint Quantum Institute, a leading center of quantum science research that is a partnership between NIST and the University of Maryland.

Ouyang and his colleagues agree that their new findings were made possible by their crystal-metal hybrid nanostructures, which offer a number of benefits over the epitaxial structures used for previous work. Epitaxy has been the principle way to create single crystal semiconductors and related devices. The new research highlights the new capabilities of these UM nanostructures, made with a process that avoids two key constraints of epitaxy — a limit on deposition semiconductor layer thickness and a rigid requirement for “lattice matching.”

The Maryland scientists note that, in addition to the enhanced capabilities of their hybrid nanostructures, the method for producing them doesn’t require a clean room facility and the materials don’t have to be formed in a vacuum, the way those made by conventional epitaxy do. “Thus it also would be much simpler and cheaper for companies to mass produce products based on our hybrid nanostructures,” Ouyang said.

UM: Addressing Big Issues, Exploring Big Ideas
Every day University of Maryland faculty and student researchers are making a deep impact on the scientific, technological, political, social, security and environmental challenges facing our nation and world. Working in partnership with federal agencies, and international and industry collaborators, they are advancing knowledge and solutions in a areas such as climate change, global security, energy, public health, information technology, food safety and security, and space exploration.

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Schematic of hybrid core-shell growth process

“Tailoring light-matter-spin interactions in colloidal hetero-nanostructures” Jiatao Zhang, Yun Tang, Kwan Lee, Min Ouyang, Nature, July 1, 2010.

This work was supported by the Office of Naval Research, the National Science Foundation (NSF), and Beckman Foundation. Facility support was from Maryland Nanocenter and its Nanoscale Imaging, Spectroscopy, and Properties Laboratory, which is supported in part by the NSF as a Materials Research Science and Engineering Centers shared experiment facility.

June 18, 2010

Louisiana’s coastline may have a savior …

… in the mighty Mississip.

The release:

Gulf oil spill: Mississippi River hydrology may help reduce oil onshore

Scientists tracking wetland characteristics find potential good news

IMAGE: Mississippi River hydrology may hold a possible answer for protecting fragile Gulf wetlands.

Click here for more information.

The Gulf of Mexico: what role will the Mississippi River play in oil washing ashore and into delta wetlands?

One of the spill’s greatest environmental threats is to Louisiana’s wetlands, scientists believe.

But there may be good news ahead.

Scientists affiliated with the National Center for Earth-surface Dynamics (NCED), a National Science Foundation (NSF) Science and Technology Center headquartered at the University of Minnesota, are using long-term field plots in Louisiana’s Wax Lake Delta to measure the baseline conditions of, and track the effects of the oil spill on, coastal Louisiana wetlands.

Robert Twilley and Guerry Holm of Louisiana State University (LSU) are investigating the degree to which two delta wetland characteristics may help mitigate oil contamination.

Fresh water head, as it’s called, the slope of the water’s surface from a river delta to the sea, and residence time of river-mouth wetlands, the time it takes water to move through a wetland at a river’s mouth, are important to understanding how delta wetlands will respond to the oil spill, say the researchers.

IMAGE: Scientists Robert Twilley and Guerry Holm are studying wetlands in Louisiana’s Wax Lake Delta.

Click here for more information.

“Since the Mississippi River is currently at a relatively high stage, we expect the river’s high volume of freshwater to act as a hydrologic barrier, keeping oil from moving into the Wax Lake Delta from the sea,” says Twilley.

Twilley and Holm are performing baseline and damage assessments on the plants and soils of, and comparing oil degradation processes in, freshwater and saltwater Louisiana wetlands.

“The Mississippi River’s ‘plumbing’ provides a potential benefit to reducing the movement of oil onshore from shelf waters,” says Twilley.

The Mississippi’s flow has been altered for flood control to protect people and infrastructure in this working delta.

River diversion structures–concrete gates built within the levees of the river–may be operated, however, to allow water to flow to specific coastal basins and floodways, says Twilley, “as a way to provide controlled floods.”

IMAGE: Warm/cool colors show current high/low elevations, respectively, in the Wax Lake Delta.

Click here for more information.

The operational features of this system “downriver to the control structure near Venice, Louisiana,” he says, “may provide a second line of defense against oil washing in.”

But any strategy using Mississippi River hydrology must be one of clear options and tradeoffs, says H. Richard Lane, program director in NSF’s Division of Earth Sciences, which funds NCED.

“As the river stage falls and protection diminishes,” says Lane, “it becomes a question of how best to distribute this freshwater resource to defend the coast from the movement of oil onshore.”

The answer, Twilley says, lies in the delicate balance of river, coastal and Gulf of Mexico processes “that must work in concert to benefit the incredible ‘ecosystem services’ this region provides to the nation.”

Louisiana wetlands “play a vital role in protecting New Orleans from hurricane damage, providing habitat for wildlife, supporting economically important fisheries, and maintaining water quality,” says Efi Foufoula-Georgiou, director of NCED.

“We must look at all options for protecting them for the future.”

In addition to his NCED and LSU affiliations, Twilley is the recipient of an NSF rapid response oil spill grant.

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May 12, 2010

DNA-based logic chips

Very cool and very fascinating in terms of extreme mass production.

The release:

DNA could be backbone of next generation logic chips

IMAGE: This is Duke University’s Chris Dwyer.

Click here for more information.

DURHAM, N.C. – In a single day, a solitary grad student at a lab bench can produce more simple logic circuits than the world’s entire output of silicon chips in a month.

So says a Duke University engineer, who believes that the next generation of these logic circuits at the heart of computers will be produced inexpensively in almost limitless quantities. The secret is that instead of silicon chips serving as the platform for electric circuits, computer engineers will take advantage of the unique properties of DNA, that double-helix carrier of all life’s information.

In his latest set of experiments, Chris Dwyer, assistant professor of electrical and computer engineering at Duke’s Pratt School of Engineering, demonstrated that by simply mixing customized snippets of DNA and other molecules, he could create literally billions of identical, tiny, waffle-looking structures.

Dwyer has shown that these nanostructures will efficiently self-assemble, and when different light-sensitive molecules are added to the mixture, the waffles exhibit unique and “programmable” properties that can be readily tapped. Using light to excite these molecules, known as chromophores, he can create simple logic gates, or switches.

These nanostructures can then be used as the building blocks for a variety of applications, ranging from the biomedical to the computational.

IMAGE: This is a closeup of a waffle.

Click here for more information.

“When light is shined on the chromophores, they absorb it, exciting the electrons,” Dwyer said. “The energy released passes to a different type of chromophore nearby that absorbs the energy and then emits light of a different wavelength. That difference means this output light can be easily differentiated from the input light, using a detector.”

Instead of conventional circuits using electrical current to rapidly switch between zeros or ones, or to yes and no, light can be used to stimulate similar responses from the DNA-based switches – and much faster.

“This is the first demonstration of such an active and rapid processing and sensing capacity at the molecular level,” Dwyer said. The results of his experiments were published online in the journal Small. “Conventional technology has reached its physical limits. The ability to cheaply produce virtually unlimited supplies of these tiny circuits seems to me to be the next logical step.”

DNA is a well-understood molecule made up of pairs of complimentary nucleotide bases that have an affinity for each other. Customized snippets of DNA can cheaply be synthesized by putting the pairs in any order. In their experiments, the researchers took advantage of DNA’s natural ability to latch onto corresponding and specific areas of other DNA snippets.

Dwyer used a jigsaw puzzle analogy to describe the process of what happens when all the waffle ingredients are mixed together in a container.

“It’s like taking pieces of a puzzle, throwing them in a box and as you shake the box, the pieces gradually find their neighbors to form the puzzle,” he said. “What we did was to take billions of these puzzle pieces, throwing them together, to form billions of copies of the same puzzle.”

IMAGE: These are many waffles.

Click here for more information.

In the current experiments, the waffle puzzle had 16 pieces, with the chromophores located atop the waffle’s ridges. More complex circuits can be created by building structures composed of many of these small components, or by building larger waffles. The possibilities are limitless, Dwyer said.

In addition to their use in computing, Dwyer said that since these nanostructures are basically sensors, many biomedical applications are possible. Tiny nanostructures could be built that could respond to different proteins that are markers for disease in a single drop of blood.

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Dwyer’s research is supported by the National Science Foundation, the Air Force Research Laboratory, the Defense Advanced Research Projects Agency and the Army Research Office. Other members of the Duke team were Constantin Pistol, Vincent Mao, Viresh Thusu and Alvin Lebeck

May 2, 2010

A library on a chip …

through nanotech.

The release:

Nanodots Breakthrough May Lead To ‘A Library On One Chip’

A researcher at North Carolina State University has developed a computer chip that can store an unprecedented amount of data – enough to hold an entire library’s worth of information on a single chip. The new chip stems from a breakthrough in the use of nanodots, or nanoscale magnets, and represents a significant advance in computer-memory technology.

“We have created magnetic nanodots that store one bit of information on each nanodot, allowing us to store over one billion pages of information in a chip that is one square inch,” says Dr. Jay Narayan, the John C. Fan Distinguished Chair Professor of Materials Science and Engineering at NC State and author of the research.

The breakthrough is that these nanodots are made of single, defect-free crystals, creating magnetic sensors that are integrated directly into a silicon electronic chip. These nanodots, which can be made uniformly as small as six nanometers in diameter, are all precisely oriented in the same way – allowing programmers to reliably read and write data to the chips.

The chips themselves can be manufactured cost-effectively, but the next step is to develop magnetic packaging that will enable users to take advantage of the chips – using something, such as laser technology, that can effectively interact with the nanodots.

The research, which was funded by the National Science Foundation, was presented as an invited talk April 7 at the 2011 Materials Research Society Spring Meeting in San Francisco.

NC State’s Department of Materials Science and Engineering is part of the university’s College of Engineering.

April 22, 2010

Quantum computing improvement

This is the first quantum computing post in a couple of months. This is a promising finding.

The release:

Bizarre matter could find use in quantum computers

Rice physicists: Odd electron mix has fault-tolerant quantum registry

IMAGE: From left, Rice physicist Rui-Rui Du, graduate students Chi Zhang and Yanhua Dai, and former postdoctoral researcher Tauno Knuuttila (not pictured) have found that odd groupings of ultracold electrons could…

Click here for more information.

HOUSTON — (April 21, 2010) — There are enticing new findings this week in the worldwide search for materials that support fault-tolerant quantum computing. New results from Rice University and Princeton University indicate that a bizarre state of matter that acts like a particle with one-quarter electron charge also has a “quantum registry” that is immune to information loss from external perturbations.

The research appeared online April 21 in Physical Review Letters. The team of physicists found that ultracold mixes of electrons caught in magnetic traps could have the necessary properties for constructing fault-tolerant quantum computers — future computers that could be far more powerful than today’s computers. The mixes of electrons are dubbed “5/2 quantum Hall liquids” in reference to the unusual quantum properties that describe their makeup.

“The big goal, the whole driving force, besides deep academic curiosity, is to build a quantum computer out of this,” said the study’s lead author Rui-Rui Du, professor of physics at Rice. “The key for that is whether these 5/2 liquids have ‘topological’ properties that would render them immune to the sorts of quantum perturbations that could cause information degradation in a quantum computer.”

Du said the team’s results indicate the 5/2 liquids have the desired properties. In the parlance of condensed-matter physics, they are said to represent a “non-Abelian” state of matter.

Non-Abelian is a mathematical term for a system with “noncommutative” properties. In math, commutative operations, like addition, are those that have the same outcome regardless of the order in which they are carried out. So, one plus two equals three, just as two plus one equals three. In daily life, commutative and noncommutative tasks are commonplace. For example, when doing the laundry, it doesn’t matter if the detergent is added before the water or the water before the detergent, but it does matter if the clothes are washed before they’re placed in the dryer.

“It will take a while to fully understand the complete implications of our results, but it is clear that we have nailed down the evidence for ‘spin polarization,’ which is one of the two necessary conditions that must be proved to show that the 5/2 liquids are non-Abelian,” Du said. “Other research teams have been tackling the second condition, the one-quarter charge, in previous experiments.”

The importance of the noncommutative quantum properties is best understood within the context of fault-tolerant quantum computers, a fundamentally new type of computer that hasn’t been built yet.

Computers today are binary. Their electrical circuits, which can be open or closed, represent the ones and zeros in binary bits of information. In quantum computers, scientists hope to use “quantum bits,” or qubits. Unlike binary ones and zeros, the qubits can be thought of as little arrows that represent the position of a bit of quantum matter. The arrow might represent a one if it points straight up or a zero if it points straight down, but it could also represent any number in between. In physics parlance, these arrows are called quantum “states.” And for certain complex calculations, being able to represent information in many different states would present a great advantage over binary computing.

The upshot of the 5/2 liquids being non-Abelian is that they have a sort of “quantum registry,” where information doesn’t change due to external quantum perturbations.

“In a way, they have internal memory of their previous state,” Du said.

The conditions needed to create the 5/2 liquids are extreme. At Rice, Tauno Knuuttila, a former postdoctoral research scientist in Du’s group, spent several years building the “demagnetization refrigerator” needed to cool 5-millimeter squares of ultrapure semiconductors to within one-10,000th of a degree of absolute zero. It took a week for Knuuttila to simply cool the nearly one-ton instrument to the necessary temperature for the Rice experiments.

The gallium arsenide semiconductors used in the tests are the most pure on the planet. They were created by Loren Pfieiffer, Du’s longtime collaborator at Princeton and Bell Labs. Rice graduate student Chi Zhang conducted additional tests at the National High Magnetic Field Laboratory in Tallahassee, Fla., to verify that the 5/2 liquid was spin- polarized.

###

Study co-authors include Zhang, Knuuttila, Pfeiffer, Princeton’s Ken West and Rice’s Yanhua Dai. The research is supported by the Department of Energy, the National Science Foundation and the Keck Foundation.

April 3, 2010

Plastic electronics may lower solar costs

Seems like a lot of news in solar cost reduction of late. In a related note, I’ve added a new link group to the sidebar — “Interesting blog topics” — and each link goes to a search for all my posts in that category. If you’re interested in solar news, that link is a great way to find everything I’ve covered in one spot.

From the link, the release:

PLASTIC ELECTRONICS COULD SLASH THE COST OF SOLAR PANELS

Posted Mar 30, 2010 By Chris Emery

A new technique developed by Princeton University engineers for producing electricity-conducting plastics could dramatically lower the cost of manufacturing solar panels.

By overcoming technical hurdles to producing plastics that are translucent, malleable and able to conduct electricity, the researchers have opened the door to broader use of the materials in a wide range of electrical devices.

With mounting concerns about global warming and energy demand, plastics could represent a low-cost alternative to indium tin oxide (ITO), an expensive conducting material currently used in solar panels, according to the researchers.

“Conductive polymers [plastics] have been around for a long time, but processing them to make something useful degraded their ability to conduct electricity,” said Yueh-Lin Loo, an associate professor of chemical engineering, who led the Princeton team. “We have figured out how to avoid this trade-off. We can shape the plastics into a useful form while maintaining high conductivity.”

A multi-institutional team reported on its new technique in a paper published online March 8 in the Proceedings of the National Academy of Sciences.

The area of research, known as “organic electronics” because plastics are carbon-based like living creatures, holds promise for producing new types of electronic devices and new ways of manufacturing existing technologies, but has been hampered by the mysterious loss of conductivity associated with moldable plastics.

“People didn’t understand what was happening,” said Loo, who co-wrote the paper. “We discovered that in making the polymers moldable, their structures are trapped in a rigid form, which prevented electrical current from traveling through them.”

Once they understood the underlying problem, Loo and her colleagues developed a way to relax the structure of the plastics by treating them with an acid after they were processed into the desired form.

Plastic transistor

Princeton researchers have developed a new way to manufacture electronic devices made of plastic, employing a process that allows the materials to be formed into useful shapes while maintaining their ability to conduct electricity. In the plastic transistor pictured here, the plastic is molded into interdigitated electrodes (orange) allowing current flow to and from the active channel (green). (Image: Loo Research Group)

Using the method, they were able to make a plastic transistor, a fundamental component of electronics that is used to amplify and switch electronic signals. They produced the electrodes of the transistor by printing the plastic onto a surface, a fast and cheap method similar to the way an ink-jet printer produces a pattern on a piece of paper.

Loo said the technique potentially could be scaled up for mass production presses akin to those used to print newspapers. “Being able to essentially paint on electronics is a big deal,” Loo said. “You could distribute the plastics in cartridges the way printer ink is sold, and you wouldn’t need exotic machines to print the patterns.”

By allowing plastic solar cells to be manufactured using low-cost printing techniques and by replacing ITO as the primary conducting material, the plastics the team developed hold potential for lowering the cost of solar panels.

Currently, the electricity generated by plastic solar cells is collected by a transparent metal conductor made of ITO. The conductor must be transparent so that sunlight can pass through it to the materials in solar cells that absorb the light energy.

A rare and pricey byproduct of mining, ITO had come under increasing demand for use in flat-screen televisions, mobile phones and other devices with display screens. “The cost of indium tin oxide is skyrocketing,” Loo said. “To bring down the costs of plastic solar cells, we need to find a replacement for ITO. Our conducting plastics allow sunlight to pass through them, making them a viable alternative.”

The researchers anticipate that the plastics also could replace expensive metals used in other electronic devices, such as flexible displays. In addition, the scientists are beginning to explore the use of the plastics in biomedical sensors that would display a certain color if a person had an infection. For instance, the plastics turn from yellow to green when exposed to nitric oxide, a chemical compound produced during ear infections in children.

If the devices could be produced at a low cost, they might be useful in developing countries that lack advanced medical facilities. “You wouldn’t need any fancy machines or lab equipment to diagnose an infection,” Loo said, “all you would need is your eyes to see the color change in the plastics.”

The co-authors of the paper were Joung Eun Yoo, who received her doctorate in chemical engineering from the University of Texas-Austin in 2009 with Loo as her adviser; Kimberly Baldwin, a high school student who spent a summer in Loo’s lab; Jacob Tarver, a Princeton chemical engineering graduate student; Enrique Gomez of Pennsylvania State University; Kwang Seok Lee and Yangming Sun of the University of Texas-Austin; Andres Garcia and Thuc-Quyen Nguyen of the University of California-Santa Barbara; and Hong Meng of DuPont Central Research and Development.

The research was supported by the National Science Foundation, the W.M. Keck Foundation and the Arnold and Mabel Beckman Foundation.

February 26, 2010

Quantum physics improving electronics and autos

Or so this news from Princeton purports.

The release:

SCIENTISTS FIND AN EQUATION FOR MATERIALS INNOVATION

Posted Feb 25, 2010By Chris Emery

Professor Emily Carter and graduate student Chen Huang developed a new way of predicting important properties of substances. The advance could speed the development of new materials and technologies. (Photo: Frank Wojciechowski)

Princeton engineers have made a breakthrough in an 80-year-old quandary in quantum physics, paving the way for the development of new materials that could make electronic devices smaller and cars more energy efficient.

By reworking a theory first proposed by physicists in the 1920s, the researchers discovered a new way to predict important characteristics of a new material before it’s been created. The new formula allows computers to model the properties of a material up to 100,000 times faster than previously possible and vastly expands the range of properties scientists can study.

“The equation scientists were using before was inefficient and consumed huge amounts of computing power, so we were limited to modeling only a few hundred atoms of a perfect material,” said Emily Carter, the engineering professor who led the project.

“But most materials aren’t perfect,” said Carter, the Arthur W. Marks ’19 Professor of Mechanical and Aerospace Engineering and Applied and Computational Mathematics. “Important properties are actually determined by the flaws, but to understand those you need to look at thousands or tens of thousands of atoms so the defects are included. Using this new equation, we’ve been able to model up to a million atoms, so we get closer to the real properties of a substance.”

By offering a panoramic view of how substances behave in the real world, the theory gives scientists a tool for developing materials that can be used for designing new technologies. Car frames made from lighter, strong metal alloys, for instance, might make vehicles more energy efficient, and smaller, faster electronic devices might be produced using nanowires with diameters tens of thousands of times smaller than that of a human hair.

Paul Madden, a chemistry professor and provost of The Queen’s College at Oxford University, who originally introduced Carter to this field of research, described the work as a “significant breakthrough” that could allow researchers to substantially expand the range of materials that can be studied in this manner. “This opens up a new class of material physics problems to realistic simulation,” he said.

The new theory traces its lineage to the Thomas-Fermi equation, a concept proposed by Llewellyn Hilleth Thomas and Nobel laureate Enrico Fermi in 1927. The equation was a simple means of relating two fundamental characteristics of atoms and molecules. They theorized that the energy electrons possess as a result of their motion — electron kinetic energy — could be calculated based how the electrons are distributed in the material. Electrons that are confined to a small region have higher kinetic energy, for instance, while those spread over a large volume have lower energy.

Understanding this relationship is important because the distribution of electrons is easier to measure, while the energy of electrons is more useful in designing materials. Knowing the electron kinetic energy helps researchers determine the structure and other properties of a material, such as how it changes shape in response to physical stress. The catch was that Thomas and Fermi’s concept was based on a theoretical gas, in which the electrons are spread evenly throughout. It could not be used to predict properties of real materials, in which electron density is less uniform.

The next major advance came in 1964, when another pair of scientists, Pierre Hohenberg and Walter Kohn, another Nobel laureate, proved that the concepts proposed by Thomas and Fermi could be applied to real materials. While they didn’t derive a final, working equation for directly relating electron kinetic energy to the distribution of electrons, Hohenberg and Kohn laid the formal groundwork that proved such an equation exists. Scientists have been searching for a working theory ever since.

Carter began working on the problem in 1996 and produced a significant advance with two postdoctoral researchers in 1999, building on Hohenberg and Kohn’s work. She has continued to whittle away at the problem since. “It would be wonderful if a perfect equation that explains all of this would just fall from the sky,” she said. “But that isn’t going to happen, so we’ve kept searching for a practical solution that helps us study materials.”

In the absence of a solution, researchers have been calculating the energy of each atom from scratch to determine the properties of a substance. The laborious method bogs down the most powerful computers if more than a few hundred atoms are being considered, severely limiting the amount of a material and type of phenomena that can be studied.

Carter knew that using the concepts introduced by Thomas and Fermi would be far more efficient, because it would avoid having to process information on the state of each and every electron.

As they worked on the problem, Carter and Chen Huang, a doctoral student in physics, concluded that the key to the puzzle was addressing a disparity observed in Carter’s earlier work. Carter and her group had developed an accurate working model for predicting the kinetic energy of electrons in simple metals. But when they tried to apply the same model to semiconductors — the conductive materials used in modern electronic devices — their predictions were no longer accurate.

“We needed to find out what we were missing that made the results so different between the semiconductors and metals,” Huang said. “Then we realized that metals and semiconductors respond differently to electrical fields. Our model was missing this.”

In the end, Huang said, the solution was a compromise. “By finding an equation that worked for these two types of materials, we found a model that works for a wide range of materials.”

Their new model, published online Jan. 26 in Physical Review B, a journal of the American Physical Society, provides a practical method for predicting the kinetic energy of electrons in semiconductors from only the electron density. The research was funded by the National Science Foundation.

Coupled with advances published last year by Carter and Linda Hung, a graduate student in applied and computational mathematics, the new model extends the range of elements and quantities of material that can be accurately simulated.

The researchers hope that by moving beyond the concepts introduced by Thomas and Fermi more than 80 years ago, their work will speed future innovations. “Before people could only look at small bits of materials and perfect crystals,” Carter said. “Now we can accurately apply quantum mechanics at scales of matter never possible before.”

February 17, 2010

Home cancer detection …

… may not be all that far off. The release doesn’t get into any sort of time-to-market predictions, but if this becomes reality it will be one amazing medical breakthrough.

The release:

Small Liquid Sensor May Detect Cancer Instantly, Could Lead to Home Detection Kit

MU researcher developing a sensor to detect diseases, such as breast cancer, in bodily fluids

Feb. 17, 2010

COLUMBIA, Mo. – What if it were possible to go to the store and buy a kit to quickly and accurately diagnose cancer, similar to a pregnancy test? A University of Missouri researcher is developing a tiny sensor, known as an acoustic resonant sensor, that is smaller than a human hair and could test bodily fluids for a variety of diseases, including breast and prostate cancers.

“Many disease-related substances in liquids are not easily tracked,” said Jae Kwon, assistant professor of electrical and computer engineering at MU. “In a liquid environment, most sensors experience a significant loss of signal quality, but by using highly sensitive, low-signal-loss acoustic resonant sensors in a liquid, these substances can be effectively and quickly detected — a brand-new concept that will result in a noninvasive approach for breast cancer detection.”

Kwon’s real-time, special acoustic resonant sensor uses micro/nanoelectromechanical systems (M/NEMS), which are tiny devices smaller than the diameter of a human hair, to directly detect diseases in body fluids. The sensor doesn’t require bulky data reading or analyzing equipment and can be integrated with equally small circuits, creating the potential for small stand-alone disease-screening systems. Kwon’s sensor also produces rapid, almost immediate results that could reduce patient anxiety often felt after waiting for other detection methods, such as biopsies, which can take several days or weeks before results are known.

“Our ultimate goal is to produce a device that will simply and quickly diagnose multiple specific diseases, and eventually be used to create ‘point of care’ systems, which are services provided to patients at their bedsides,” Kwon said. “The sensor has strong commercial potential to be manifested as simple home kits for easy, rapid and accurate diagnosis of various diseases, such as breast cancer and prostate cancer.”

Last January, Kwon was awarded a $400,000, five-year National Science Foundation CAREER Award to continue his effort on this sensor research. The CAREER award is the NSF’s most prestigious award in support of junior faculty members who exemplify the role of teacher-scholars through outstanding research, excellent teaching, and the integration of education and research. Kwon’s sensor research has been published in the IEEE International Conference on Solid-state, Sensors, Actuators and Microsystems and the IEEE Conference on Sensors.

–30–

February 12, 2010

Nanogenerators and electric clothes

(Number two of two posts on nanotechnology and electricity. Hit this link for part one)

The idea of smart clothes has been around for ages. Looks like this might just be a breakthrough to electric clothing becoming a reality.

That oughta bring a whole new meaning to “social networking.” Thank you, thank you, I’ll be here all weekend. Be sure and come back tomorrow for the complimentary Saturday buffet and half-price happy hour.

The release:

New fiber nanogenerators could lead to electric clothing

By Sarah Yang, Media Relations | 12 February 2010

BERKELEY — In research that gives literal meaning to the term “power suit,” University of California, Berkeley, engineers have created energy-scavenging nanofibers that could one day be woven into clothing and textiles.

These nano-sized generators have “piezoelectric” properties that allow them to convert into electricity the energy created through mechanical stress, stretches and twists.

“This technology could eventually lead to wearable ‘smart clothes’ that can power hand-held electronics through ordinary body movements,” said Liwei Lin, UC Berkeley professor of mechanical engineering and head of the international research team that developed the fiber nanogenerators.

Because the nanofibers are made from organic polyvinylidene fluoride, or PVDF, they are flexible and relatively easy and cheap to manufacture.

Although they are still working out the exact calculations, the researchers noted that more vigorous movements, such as the kind one would create while dancing the electric boogaloo, should theoretically generate more power. “And because the nanofibers are so small, we could weave them right into clothes with no perceptible change in comfort for the user,” said Lin, who is also co-director of the Berkeley Sensor and Actuator Center at UC Berkeley.

The fiber nanogenerators are described in this month’s issue of Nano Letters, a peer-reviewed journal published by the American Chemical Society.

The goal of harvesting energy from mechanical movements through wearable nanogenerators is not new. Other research teams have previously made nanogenerators out of inorganic semiconducting materials, such as zinc oxide or barium titanate. “Inorganic nanogenerators — in contrast to the organic nanogenerators we created — are more brittle and harder to grow in significant quantities,” Lin said.

The tiny nanogenerators have diameters as small as 500 nanometers, or about 100 times thinner than a human hair and one-tenth the width of common cloth fibers. The researchers repeatedly tugged and tweaked the nanofibers, generating electrical outputs ranging from 5 to 30 millivolts and 0.5 to 3 nanoamps.

Furthermore, the researchers report no noticeable degradation after stretching and releasing the nanofibers for 100 minutes at a frequency of 0.5 hertz (cycles per second).

Lin’s team at UC Berkeley pioneered the near-field electrospinning technique used to create and position the polymeric nanogenerators 50 micrometers apart in a grid pattern. The technology enables greater control of the placement of the nanofibers onto a surface, allowing researchers to properly align the fiber nanogenerators so that positive and negative poles are on opposite ends, similar to the poles on a battery.

Without this control, the researchers explained, the negative and positive poles might cancel each other out and reducing energy efficiency.

The researchers demonstrated energy conversion efficiencies as high as 21.8 percent, with an average of 12.5 percent.

“Surprisingly, the energy efficiency ratings of the nanofibers are much greater than the 0.5 to 4 percent achieved in typical power generators made from experimental piezoelectric PVDF thin films, and the 6.8 percent in nanogenerators made from zinc oxide fine wires,” said the study’s lead author, Chieh Chang, who conducted the experiments while he was a graduate student in mechanical engineering at UC Berkeley.

“We think the efficiency likely could be raised further,” Lin said. “For our preliminary results, we see a trend that the smaller the fiber we have, the better the energy efficiency. We don’t know what the limit is.”

Other co-authors of the study are Yiin-Kuen Fuh, a UC Berkeley graduate student in mechanical engineering; Van H. Tran, a graduate student at the Technische Universität München (Technical University of Munich) in Germany; and Junbo Wang, a researcher at the Institute of Electronics at the Chinese Academy of Sciences in Beijing, China.

The National Science Foundation and the Defense Advanced Research Projects Agency helped support this research.

fiber nanogenerator
Shown is a fiber nanogenerator on a plastic substrate created by UC Berkeley scientists. The nanofibers can convert energy from mechanical stresses and into electricity, and could one day be used to create clothing that can power small electronics. (Chieh Chang, UC Berkeley)

February 2, 2010

Spider man, spider man …

… does whatever a spider can.

I’ll just let the release from yesterday finish this thought process for me:

New adhesive device could let humans walk on walls

Could humans one day walk on walls, like Spider-Man? A palm-sized device invented at Cornell that uses water surface tension as an adhesive bond just might make it possible.

The rapid adhesion mechanism could lead to such applications as shoes or gloves that stick and unstick to walls, or Post-it-like notes that can bear loads, according to Paul Steen, professor of chemical and biomolecular engineering, who invented the device with Michael Vogel, a former postdoctoral associate.

The device is the result of inspiration drawn from a beetle native to Florida, which can adhere to a leaf with a force 100 times its own weight, yet also instantly unstick itself. Research behind the device is published online Feb. 1 in Proceedings of the National Academy of Sciences.

The device consists of a flat plate patterned with holes, each on the order of microns (one-millionth of a meter). A bottom plate holds a liquid reservoir, and in the middle is another porous layer. An electric field applied by a common 9-volt battery pumps water through the device and causes droplets to squeeze through the top layer. The surface tension of the exposed droplets makes the device grip another surface – much the way two wet glass slides stick together.

“In our everyday experience, these forces are relatively weak,” Steen said. “But if you make a lot of them and can control them, like the beetle does, you can get strong adhesion forces.”

For example, one of the researchers’ prototypes was made with about 1,000 300-micron-sized holes, and it can hold about 30 grams – more than 70 paper clips. They found that as they scaled down the holes and packed more of them onto the device, the adhesion got stronger. They estimate, then, that a one-square-inch device with millions of 1-micron-sized holes could hold more than 15 pounds.

To turn the adhesion off, the electric field is simply reversed, and the water is pulled back through the pores, breaking the tiny “bridges” created between the device and the other surface by the individual droplets.

The research builds on previously published work that demonstrated the efficacy of what’s called electro-osmotic pumping between surface tension-held interfaces, first by using just two larger water droplets.

One of the biggest challenges in making these devices work, Steen said, was keeping the droplets from coalescing, as water droplets tend to do when they get close together. To solve this, they designed their pump to resist water flow while it’s turned off.

Steen envisions future prototypes on a grander scale, once the pump mechanism is perfected, and the adhesive bond can be made even stronger. He also imagines covering the droplets with thin membranes – thin enough to be controlled by the pump but thick enough to eliminate wetting. The encapsulated liquid could exert simultaneous forces, like tiny punches.

“You can think about making a credit card-sized device that you can put in a rock fissure or a door, and break it open with very little voltage,” Steen said. “It’s a fun thing to think about.”

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The research was funded primarily by the Defense Advanced Research Projects Agency and also by the National Science Foundation.

November 27, 2009

Semiconducting nanowires are coming

With all the news about nanotechnology and wiring that’s been coming out over the last year or so, this release is no surprise.

The release:

November 26, 2009

Nanowires key to future transistors, electronics

WEST LAFAYETTE, Ind. –

Nanowire formation
Download photo
caption below

A new generation of ultrasmall transistors and more powerful computer chips using tiny structures called semiconducting nanowires are closer to reality after a key discovery by researchers at IBM, Purdue University and the University of California at Los Angeles.The researchers have learned how to create nanowires with layers of different materials that are sharply defined at the atomic level, which is a critical requirement for making efficient transistors out of the structures.

 

“Having sharply defined layers of materials enables you to improve and control the flow of electrons and to switch this flow on and off,” said Eric Stach, an associate professor of materials engineering at Purdue.

Electronic devices are often made of “heterostructures,” meaning they contain sharply defined layers of different semiconducting materials, such as silicon and germanium. Until now, however, researchers have been unable to produce nanowires with sharply defined silicon and germanium layers. Instead, this transition from one layer to the next has been too gradual for the devices to perform optimally as transistors.

The new findings point to a method for creating nanowire transistors.

The findings are detailed in a research paper appearing Friday (Nov. 27) in the journal Science. The paper was written by Purdue postdoctoral researcher Cheng-Yen Wen, Stach, IBM materials scientists Frances Ross, Jerry Tersoff and Mark Reuter at the Thomas J. Watson Research Center in Yorktown Heights, N.Y, and Suneel Kodambaka, an assistant professor at UCLA’s Department of Materials Science and Engineering.

Whereas conventional transistors are made on flat, horizontal pieces of silicon, the silicon nanowires are “grown” vertically. Because of this vertical structure, they have a smaller footprint, which could make it possible to fit more transistors on an integrated circuit, or chip, Stach said.

“But first we need to learn how to manufacture nanowires to exacting standards before industry can start using them to produce transistors,” he said.

Nanowires might enable engineers to solve a problem threatening to derail the electronics industry. New technologies will be needed for industry to maintain Moore’s law, an unofficial rule stating that the number of transistors on a computer chip doubles about every 18 months, resulting in rapid progress in computers and telecommunications. Doubling the number of devices that can fit on a computer chip translates into a similar increase in performance. However, it is becoming increasingly difficult to continue shrinking electronic devices made of conventional silicon-based semiconductors.

“In something like five to, at most, 10 years, silicon transistor dimensions will have been scaled to their limit,” Stach said.

Transistors made of nanowires represent one potential way to continue the tradition of Moore’s law.

The researchers used an instrument called a transmission electron microscope to observe the nanowire formation. Tiny particles of a gold-aluminum alloy were first heated and melted inside a vacuum chamber, and then silicon gas was introduced into the chamber. As the melted gold-aluminum bead absorbed the silicon, it became “supersaturated” with silicon, causing the silicon to precipitate and form wires. Each growing wire was topped with a liquid bead of gold-aluminum so that the structure resembled a mushroom.

Then, the researchers reduced the temperature inside the chamber enough to cause the gold-aluminum cap to solidify, allowing germanium to be deposited onto the silicon precisely and making it possible to create a heterostructure of silicon and germanium.

The cycle could be repeated, switching the gases from germanium to silicon as desired to make specific types of heterostructures, Stach said.

Having a heterostructure makes it possible to create a germanium “gate” in each transistor, which enables devices to switch on and off.

The work is based at IBM’s Thomas J. Watson Research Center and Purdue’s Birck Nanotechnology Center in the university’s Discovery Park and is funded by the National Science Foundation through the NSF’s Electronic and Photonic Materials Program in the Division of Materials Research.

PHOTO CAPTION:
Researchers are closer to using tiny devices called semiconducting nanowires to create a new generation of ultrasmall transistors and more powerful computer chips. The researchers have grown the nanowires with sharply defined layers of silicon and germanium, offering better transistor performance. As depicted in this illustration, tiny particles of a gold-aluminum alloy were alternately heated and cooled inside a vacuum chamber, and then silicon and germanium gases were alternately introduced. As the gold-aluminum bead absorbed the gases, it became “supersaturated” with silicon and germanium, causing them to precipitate and form wires. (Purdue University, Birck Nanotechnology Center/Seyet LLC)

November 22, 2009

The search engine as teacher

Who’d a thunk it?!?

The release:

Search engines are source of learning

Search engine use is not just part of our daily routines; it is also becoming part of our learning process, according to Penn State researchers.

The researchers sought to discover the cognitive processes underlying searching. They examined the search habits of 72 participants while conducting a total of 426 searching tasks. They found that search engines are primarily used for fact checking users’ own internal knowledge, meaning that they are part of the learning process rather than simply a source for information. They also found that people’s learning styles can affect how they use search engines.

“Our results suggest the view of Web searchers having simple information needs may be incorrect,” said Jim Jansen, associate professor of information sciences and technology. “Instead, we discovered that users applied simple searching expressions to support their higher-level information needs.”

Jansen said the results of this study provide useful information about how search engine use has evolved over the past decade and clues about how to design better search engines to address users’ learning needs in the future. He and Brian Smith, associate professor information sciences and technology and Danielle Booth, former Penn State student, published their findings in the November issue of Information Processing and Management.

“If we can incorporate cognitive, affective and situational aspects of a person, there is the potential to really move search performance forward,” Jansen said. “At its core, we are getting to the motivational elements of search.”

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National Science Foundation and the Air Force Office of Scientific Research funded this research.

October 13, 2009

Web 2.0 and privacy

As it turns out — not, surprisingly I might add — not so much.

The release:

Looking for privacy in the clouds

DURHAM, N.C. — Millions of Internet users have been enjoying the fun — and free — services provided by advertiser-supported online social networks like Facebook. But Landon Cox, a Duke University assistant professor of computer science, worries about the possible down side — privacy problems.

When people post pictures or political opinions to share with their friends, they’re actually turning them over to the owners of the network as well.

“My concern is that they’re under the control of a central entity,” Cox said. “The social networks currently control all the information that users throw into them. I don’t think that’s necessarily evil. But it raises some concerns.”

For instance, MIT student experimenters have demonstrated the ability to sneak in and download more than 70,000 Facebook profiles. And a BBC technology program also showed how such personal information could be stolen.

“A disgruntled employee could leak information about social network users,” Cox said. “They could also become attractive targets for hackers and other computer ne’er-do-wells.”

Though users may not have caught this when they clicked to accept a site’s terms of service, they’ve largely signed away the rights to their own data by joining an Online Social Network. “These rights commonly include a license to display and distribute all content posted by users in any way the provider sees fit,” Cox said.

To delve deeper into these issues and begin the search for alternatives, Cox recently won a $498,000, three-year grant from the National Science Foundation. The funding is part of the federal stimulus package called the American Recovery & Reinvestment Act of 2009 (ARRA). He and two of his graduate students, Amre Shakimov and Dongtao Liu, are collaborating closely with Ramon Caceres at AT&T Labs in Florham Park, N.J., which is also a major supporter.

“What the grant will do is fund research into alternatives for providing social networking services that don’t concentrate all this information in a single place,” he said. Cox’s notion is instead to create what network architects would call a “peer-to-peer” system architecture in which information is spread out. Being distributed, individual data is thus harder to steal or otherwise exploit.

“The basic idea is that users would control and store their own information and then share it directly with their friends instead of it being mediated through a site like Facebook. And there are some interesting challenges that go along with decomposing something like Facebook into a peer-to-peer system.

“Facebook is a great service because it’s highly available and really fast. When you break something into thousands and millions of different pieces instead, you’d want to try to recreate the same availability and performance. That’s the research challenge we’re going to be looking at over the next three years.”

Cox proposed three possible options in a report for the Association for Computing Machinery’s Workshop for Online Social Networks in Barcelona in August 2009. In each, users would load their personal information into what is called a “Virtual Individual Server,” or VIS.

One option would host each social network user’s VIS on his or her own desktop. “But the problem with desktop machines is that they go down all the time,” Cox said. “When desktops are shut off they are not available.”

An alternative idea is to distribute VISs within redundant “clouds” of servers such as those offered by the Amazon Elastic Computer Cloud. “Amazon will run little computers on your behalf out in their infrastructure,” Cox said. “The nice thing about that is the service will never go down. But the problem is that it’s very expensive. It costs about $50 a month to have just one server out in the cloud.”

A third notion is called “hybrid decentralization.” The idea is to keep VISs on desktops when possible but switch to the more costly and reliable cloud distribution option when individual desktops go offline.

“So there are these different tradeoffs,” Cox said. “Users can try to put their information in clouds of servers, which are going to be highly available but expensive. Or they could try to store it on their own machines, which would be cheap but subject to service interruptions.”

Under his NSF stimulus grant, Cox will be able to pay Shakimov and Liu for three years and fund some of his own work to explore those options. Other AT&T Labs research participants besides Caceres are Alexander Varshavsky and Kevin Li. Amazon is also providing equipment support.

“The research will point in a couple of directions,” he said. “Can we get a desktop machine to intelligently switch over to a cloud? Can we reduce the cost by only using a cloud when the desktop is not available?”

Or perhaps the same information can be put in a number of places in the hope that at least one of those computers is always working. “So in addition to serving my own stuff I might ask my friends to serve my stuff as well,” Cox said.

“The problem there is that now you’re trusting somebody else to serve and store your data. We have some interesting challenges ahead.”

###

October 9, 2009

Petaflop academic supercomputer

Now that’s fast.

The release:

Kraken becomes first academic machine to achieve petaflop

IMAGE: This is the newly upgraded Kraken supercomputer, capable of a peak performance of more than one petaflop

Click here for more information.

The National Institute for Computational Sciences’ (NICS’s) Cray XT5 supercomputer—Kraken—has been upgraded to become the first academic system to surpass a thousand trillion calculations a second, or one petaflop, a landmark achievement that will greatly accelerate science and place Kraken among the top five computers in the world.

Managed by the University of Tennessee (UT) for the National Science Foundation (NSF), the system came online Oct. 5 with a peak performance of 1.03 petaflops. It features more than 16,000 six-core 2.6-GHz AMD Istanbul processors with nearly 100,000 compute cores.

In addition, an upgrade to 129 terabytes of memory (the equivalent of more than 13 thousand movies on DVD) effectively doubles the size of Kraken for researchers running some of the world’s most sophisticated 3-D scientific computing applications. Simulation has become a key tool for researchers in a number of fields, from climate change to materials.

“At over a petaflop of peak computing power, and the ability to routinely run full machine jobs, Kraken will dominate large-scale NSF computing in the near future,” said NICS Project Director Phil Andrews. “Its unprecedented computational capability and total available memory will allow academic users to treat problems that were previously inaccessible.”

For example, understanding the mechanism behind the explosion of core-collapse supernovas will reveal much about our universe (these cataclysmic events are responsible for more than half the elements in the universe). Essentially three phenomena are being simulated to explore these explosions: hydrodynamics, nuclear burning or fusion, and neutrino transport, said UT astrophysicist Bronson Messer.

At the terascale, or trillions of calculations per second, Messer and his team were forced to simulate the star in 1-D as a perfect sphere and with unrealistic fusion physics. “Now, however, we are getting closer to physical reality,” said Messer. “With petascale capability, we can simulate all three phenomena simultaneously with significant realism. This brings us closer to understanding the explosion mechanism and being able to make meaningful predictions.”

From the physical makeup of the universe to the causes of global warming to the roles of proteins in disease, Kraken’s increased computing muscle will reach far and wide.

As the main computational resource for NICS, the new system is linked to the NSF-supported TeraGrid, a network of supercomputers across the country that is the world’s largest computational platform for open scientific research.

The system and the resulting NICS organization are the result of an NSF Track 2 award of $65 million to the University of Tennessee and its partners to provide for next-generation high-performance computing (HPC). The award was won in an open competition among HPC institutions vying to guarantee America’s continued competitiveness through the next generation of supercomputers (systems greater than 10 teraflops and into the petascale).

“While reaching the petascale is a remarkable achievement in itself, the real strides will be made in the new science that petascale computing will enable,” said Thomas Zacharia, NICS principal investigator, professor in electrical and computer engineering at the University of Tennessee and deputy director for science and technology at Oak Ridge National Laboratory. “Kraken is a game changer for research.”

###

September 2, 2009

Magnetic graphene

Graphene news from Virginia Commonwealth University:

Researchers design new graphene-based, nano-material with magnetic properties

A possible pathway to simply synthesize ferromagnetic graphene

Ferromagnetic Graphone Sheet. Puru Jena/VCU.

An international team of researchers has designed a new graphite-based, magnetic nano-material that acts as a semiconductor and could help material scientists create the next generation of electronic devices like microchips.

The team of researchers from Virginia Commonwealth University; Peking University in Beijing, China; the Chinese Academy of Science in Shanghai, China; and Tohoku University in Sedai, Japan; used theoretical computer modeling to design the new material they called graphone, which is derived from an existing material known as graphene.

Graphene, created by scientists five years ago, is 200 times stronger than steel, its electrons are highly mobile and it has unique optical and transport properties. Some experts believe that graphene may be more versatile than carbon nanotubes, and the ability to make graphene magnetic adds to its potential for novel applications in spintronics. Spintronics is a process using electron spin to synthesize new devices for memory and data processing.

Although graphene’s properties can be significantly modified by introducing defects and by saturating with hydrogen, it has been very difficult for scientists to manipulate the structure to make it magnetic.

“The new material we are predicting – graphone – makes graphene magnetic simply by controlling the amount of hydrogen coverage – basically, how much hydrogen is put on graphene. It avoids previous difficulties associated with the synthesis of magnetic graphene,” said Puru Jena, Ph.D., distinguished professor in the VCU Department of Physics.

“There are many possibilities for engineering new functional materials simply by changing their composition and structure. Our findings may guide researchers in the future to discover this material in the laboratory and to explore its potential technological applications,” said Jena.

“One of the important impacts of this research is that semi-hydrogenation provides us a very unique way to tailor magnetism. The resulting ferromagnetic graphone sheet will have unprecedented possibilities for the applications of graphene-based materials,” said Qiang Sun, Ph.D., research associate professor with the VCU team.

The study appeared online Aug. 31 in the journal Nano Letters, a publication of the American Chemical Society. The work was supported by a grant from the National Natural Science Foundation of China, The National Science Foundation and by the U.S. Department of Energy. Read the article abstract here.

The first author of this paper is Jian Zhou, a Ph.D. student at Peking University. The other authors include Qian Wang, Ph.D., a research associate professor at VCU; Xiaoshuan Chen, Ph.D., a professor at the Shanghai Institute of Technical Physics; and Yoshiyuki Kawazoe, Ph.D.,  a professor at Tohoku University.

About VCU and the VCU Medical Center:


Virginia Commonwealth University is the largest university in Virginia with national and international rankings in sponsored research. Located on two downtown campuses in Richmond, VCU enrolls 32,000 students in 205 certificate and degree programs in the arts, sciences and humanities. Sixty-five of the programs are unique in Virginia, many of them crossing the disciplines of VCU’s 15 schools and one college. MCV Hospitals and the health sciences schools of Virginia Commonwealth University compose the VCU Medical Center, one of the nation’s leading academic medical centers. For more, see www.vcu.edu.

August 16, 2009

Nanolaser could lead to optical computer and more

Sounds promising. The field of alternate computation — such a quantum, optical, biological, et. al. — is always interesting.

The release:

New nanolaser key to future optical computers and technologies

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 Sunday (Aug. 16) 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.

IMAGE CAPTION:

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. (Birck Nanotechnology Center, Purdue University)

A publication-quality image is available at http://news.uns.purdue.edu/images/+2009/shalaev-spasers.jpg

Abstract on the research in this release is available at: http://news.uns.purdue.edu/x/2009b/090817ShalaevSpasers.html

STORY AND PHOTO CAN BE FOUND AT:

http://news.uns.purdue.edu/x/2009b/090817ShalaevSpasers.html

July 3, 2009

Second Life contributes to social research

I’ve blogged on MMORPGs and social research here and here amonst other times, and I still find it fascinating — although not surprising — that university research is turning to virtual communities for social research. It’s real people interacting and simply by its nature everything collected is both data rich and pre-formatted for the most part. A researchers dream.

The latest release on virtual communities and social research (aside from dk: I spotted a typo in the release. Can you find it?):

Second Life data offers window into how trends spread

ANN ARBOR, Mich.—Do friends wear the same style of shoe or see the same movies because they have similar tastes, which is why they became friends in the first place? Or once a friendship is established, do individuals influence each other to adopt like behaviors?

Social scientists don’t know for sure. They’re still trying to understand the role social influence plays in the spreading of trends because the real world doesn’t keep track of how people acquire new items or preferences.

But the virtual world Second Life does. Researchers from the University of Michigan have taken advantage of this unique information to study how “gestures” make their way through this online community. Gestures are code snippets that Second Life avatars must acquire in order to make motions such as dancing, waving or chanting.

Roughly half of the gestures the researchers studied made their way through the virtual world friend by friend.

“We could have found that most everyone goes to the store to buy gestures, but it turns out about 50 percent of gesture transfers are between people who have declared themselves friends. The social networks played a major role in the distribution of these assets,” said Lada Adamic, an assistant professor in the School of Information and the Department of Electrical Engineering and Computer Science.

Adamic is an author of a paper on the research that graduate student Eytan Bakshy will present on July 7 at the Association for Computer Machinery’s Conference on Electronic Conference in Stanford, Calif. Bakshy is a doctoral student in the School of Information.

“There’s been a high correspondence between the real world and virtual worlds,” Adamic said. “We’re not saying this is exactly how people share in the real world, but we believe it does have some relevance.”

This study is one of the first to model social influence in a virtual world because of the rarity of having access to information about how information, assets or ideas propagate. In Second Life, the previous owner of a gesture is listed.

The researchers also found that the gestures that spread from friend to friend were not distributed as broadly as ones that were distributed outside of the social network, such as those acquired in stores or as give-aways.

And they discovered that the early adopters of gestures who are among the first 5-10 percent to acquire new assets are not the same as the influencers, who tend to distribute them most broadly. This aligns with what social scientists have found.

“In our study, we sought to develop a more rigorous understanding of social processes that underlies many cultural and economic phenomena,” Bakshy said. “While some of our findings may seem quite intuitive, what I find most exciting is that we were actually able to test some rather controversial and competing hypotheses about the role of social networks in influence.”

The researchers examined 130 days worth of gesture transfers in late 2008 and early 2009. They looked at 100,229 users and 106,499 gestures. They obtained the data from Linden Lab, the maker of Second Life. Personally-identifying information had been removed.

 

###

 

The paper is called, “Social Influence and the Diffusion of User-Created Content.” The research is funded by the National Science Foundation. Physics graduate student Brian Karrer is also a co-author.

For more information:

Full text of paper:
http://www-personal.umich.edu/~ladamic/

ACM Conference on Electronic Commerce:
http://www.sigecom.org/ec09/

June 12, 2009

Assembly with graphene

Interesting research on the properties of one of the more exciting nanotech materials out there.

The release:

Penn materials scientist finds plumber’s wonderland on graphene

IMAGE: This is an electron micrograph showing the formation of interconnected carbon nanostructures on a graphene substrate, which may be harnessed to make future electronic devices.

Click here for more information. 

PHILADELPHIA –- Engineers from the University of Pennsylvania, Sandia National Laboratories and Rice University have demonstrated the formation of interconnected carbon nanostructures on graphene substrate in a simple assembly process that involves heating few-layer graphene sheets to sublimation using electric current that may eventually lead to a new paradigm for building integrated carbon-based devices.

Curvy nanostructures such as carbon nanotubes and fullerenes have extraordinary properties but are extremely challenging to pick up, handle and assemble into devices after synthesis. Penn materials scientist Ju Li and Sandia scientist Jianyu Huang have come up with a novel idea to construct curvy nanostructures directly integrated on graphene, taking advantage of the fact that graphene, an atomically thin two-dimensional sheet, bends easily after open edges have been cut on it, which can then fuse with other open edges permanently, like a plumber connecting metal fittings.

The “knife” and “welding torch” used in the experiments, which were performed inside an electron microscope, was electrical current from a Nanofactory scanning probe, generating up to 2000°C of heat. Upon applying the electrical current to few-layer graphene, they observed the in situ creation of many interconnected, curved carbon nanostructures, such as “fractional nanotube”-like graphene bi-layer edges, or BLEs; BLE rings on graphene equivalent to “anti quantum-dots”; and nanotube-BLE assembly connecting multiple layers of graphene.

Remarkably, researchers observed that more than 99 percent of the graphene edges formed during sublimation were curved BLEs rather than flat monolayer edges, indicating that BLEs are the stable edges in graphene, in agreement with predictions based on symmetry considerations and energetic calculations. Theory also predicts these BLEs, or “fractional nanotubes,” possess novel properties of their own and may find applications in devices.

The study is published in the current issue of the journal Proceedings of the National Academy of Sciences. Short movies of the fabrication of these nanostructures can be viewed at www.youtube.com/user/MaterialsTheory.

Li and Huang observed the creation of these interconnected carbon nanostructures using the heat of electric current and a high-resolution transmission electron microscope. The current, once passed through the graphene layers, improved the crystalline quality and surface cleanness of the graphene as well, both important for device fabrication.

The sublimation of few-layer graphene, such as a 10-layer stack, is advantageous over the sublimation of monolayers. In few-layer graphene, layers spontaneously fuse together forming nanostructures on top of one or two electrically conductive, extended, graphene sheets.

During heating, both the flat graphene sheets and the self-wrapping nanostructures that form, like bilayer edges and nanotubes, have unique electronic properties important for device applications. The biggest obstacle for engineers has been wrestling control of the structure and assembly of these nanostructures to best exploit the properties of carbon. The discoveries of self-assembled novel carbon nanostructures may circumvent the hurdle and lead to new approach of graphene-based electronic devices.

Researchers induced the sublimation of multilayer graphene by Joule-heating, making it thermodynamically favorable for the carbon atoms at the edge of the material to escape into the gas phase, leaving freshly exposed edges on the solid graphene. The remaining graphene edges curl and often welded together to form BLEs. Researchers attribute this behavior to nature’s driving force to reduce capillary energy, dangling bonds on the open edges of monolayer graphene, at the cost of increased bending energy.

“This study demonstrates it is possible to make and integrate curved nanostructures directly on flat graphene, which is extended and electrically conducting,” said Li, associate professor in the Department of Materials Science and Engineering in Penn’s School of Engineering and Applied Science. “Furthermore, it demonstrates that multiple graphene sheets can be intentionally interconnected. And the quality of the plumbing is exceptionally high, better than anything people have used for electrical contacts with carbon nanotubes so far. We are currently investigating the fundamental properties of graphene bi-layer edges, BLE rings and nanotube-BLE junctions.”

 

###

 

The study was performed by Li and Liang Qi of Penn, Jian Yu Huang and Ping Lu of the Center for Integrated Nanotechnologies at Sandia and Feng Ding and Boris I. Yakobson of the Department of Mechanical Engineering and Materials Science at Rice.

It was supported by the National Science Foundation, the Air Force Office of Scientific Research, the Honda Research Institute, the Department of Energy and the Office of Naval Research.

June 4, 2009

Photon driven nanomotor

Fair warning to all readers, a major press release dump is coming. Mostly nanotechnology news.

First up is research on a molecular nanomotor driven by light.

The release:

New, light-driven nanomotor is simpler, more promising, scientists say

GAINESVILLE, Fla. — Sunflowers track the sun as it moves from east to west. But people usually have to convert sunlight into electricity or heat to put its power to use.

Now, a team of University of Florida chemists is the latest to report a new mechanism to transform light straight into motion – albeit at a very, very, very tiny scale.

In a paper expected to appear soon in the online edition of the journal Nano Letters, the UF team reports building a new type of “molecular nanomotor” driven only by photons, or particles of light. While it is not the first photon-driven nanomotor, the almost infinitesimal device is the first built entirely with a single molecule of DNA — giving it a simplicity that increases its potential for development, manufacture and real-world applications in areas ranging from medicine to manufacturing, the scientists say.

“It is easy to assemble, has fewer parts and theoretically should be more efficient,” said Huaizhi Kang, a doctoral student in chemistry at UF and the first author of the paper.

The scale of the nanomotor is almost vanishingly small.

In its clasped, or closed, form, the nanomotor measures 2 to 5 nanometers — 2 to 5 billionths of a meter. In its unclasped form, it extends as long as 10 to 12 nanometers. Although the scientists say their calculations show it uses considerably more of the energy in light than traditional solar cells, the amount of force it exerts is proportional to its small size.

But that won’t necessarily limit its potential.

In coming years, the nanomotor could become a component of microscopic devices that repair individual cells or fight viruses or bacteria. Although in the conceptual stage, those devices, like much larger ones, will require a power source to function. Because it is made of DNA, the nanomotor is biocompatible. Unlike traditional energy systems, the nanomotor also produces no waste when it converts light energy into motion.

“Preparation of DNA molecules is relatively easy and reproducible, and the material is very safe,” said Yan Chen, a UF chemistry doctoral student and one of the authors of the paper.

Applications in the larger world are more distant. Powering a vehicle, running an assembly line or otherwise replacing traditional electricity or fossil fuels would require untold trillions of nanomotors, all working together in tandem — a difficult challenge by any measure.

“The major difficulty lies ahead,” said Weihong Tan, a UF professor of chemistry and physiology, author of the paper and the leader of the research group reporting the findings. “That is how to collect the molecular level force into a coherent accumulated force that can do real work when the motor absorbs sunlight.”

Tan added that the group has already begun working on the problem.

“Some prototype DNA nanostructures incorporating single photo-switchable motors are in the making which will synchronize molecular motions to accumulate forces,” he said.

To make the nanomotor, the researchers combined a DNA molecule they created in the lab with azobenzene, a chemical compound that responds to light. A high-energy photon prompts one response; lower energy another.

To demonstrate the movement, the researchers attached a fluorophore, or light-emitter, to one end of the nanomotor and a quencher, which can quench the emitting light, to the other end. Their instruments recorded emitted light intensity that corresponded to the motor movement.

“Radiation does cause things to move from the spinning of radiometer wheels to the turning of sunflowers and other plants toward the sun,” said Richard Zare, distinguished professor and chairman of chemistry at Stanford University. “What Professor Tan and co-workers have done is to create a clever light-actuated nanomotor involving a single DNA molecule. I believe it is the first of its type.”

 

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The National Institutes of Health and the National Science Foundation funded the research. The other coauthors of this paper are Haipeng Liu, Joseph A. Phillips, Zehui Cao, Youngmi Kim, Zunyi Yang and Jianwei Li.

June 2, 2009

Making water run uphill …

… through lasers and nanostructures. Lots of possible apps here, plus it’s just freaking cool.

The release:

Scientists create metal that pumps liquid uphill

Ultra-fast laser makes metal that attracts, repels and guides liquids

IMAGE: Chunlei Guo uses the femtosecond laser (behind him) to create nanostructures in metal that can move liquid uphill.

Click here for more information. 

In nature, trees pull vast amounts of water from their roots up to their leaves hundreds of feet above the ground through capillary action, but now scientists at the University of Rochester have created a simple slab of metal that lifts liquid using the same principle—but does so at a speed that would make nature envious.

The metal, revealed in an upcoming issue of Applied Physics Letters, may prove invaluable in pumping microscopic amounts of liquid around a medical diagnostic chip, cooling a computer’s processor, or turning almost any simple metal into an anti-bacterial surface.

“We’re able to change the surface structure of almost any piece of metal so that we can control how liquid responds to it,” says Chunlei Guo, associate professor of optics at the University of Rochester. “We can even control the direction in which the liquid flows, or whether liquid flows at all.”

Guo and his assistant, Anatoliy Vorobyev, use an ultra-fast burst of laser light to change the surface of a metal, forming nanoscale and microscale pits, globules, and strands across the metal’s surface. The laser, called a femtosecond laser, produces pulses lasting only a few quadrillionths of a second—a femtosecond is to a second what a second is to about 32 million years. During its brief burst, Guo’s laser unleashes as much power as the entire electric grid of North America does, all focused onto a spot the size of a needlepoint, he says.

The wicking process, which on Guo’s metal moves at a quick one centimeter per second speed against gravity, is very similar to the phenomenon that pulls spilled milk into a paper towel or creates “tears of wine” in a wineglass—molecular attractions and evaporation combine to move a liquid against gravity, says Guo. Likewise, Guo’s nanostructures change the way molecules of a liquid interact with the molecules of the metal, allowing them to become more or less attracted to each other, depending on Guo’s settings. At a certain size, the metal nanostructures adhere more readily to the liquid’s molecules than the liquid’s molecules adhere to each other, causing the liquid to quickly spread out across the metal. Combined with the effects of evaporation as the liquid spreads, this molecular interaction creates the fast wicking effect in Guo’s metals.

Adding laser-etched channels into the metal further enhances Guo’s control of the liquid.

“Imagine a huge waterway system shrunk down onto a tiny chip, like the electronic circuit printed on a microprocessor, so we can perform chemical or biological work with a tiny bit of liquid,” says Guo. “Blood could precisely travel along a certain path to a sensor for disease diagnostics. With such a tiny system, a nurse wouldn’t need to draw a whole tube of blood for a test. A scratch on the skin might contain more than enough cells for a micro-analysis.”

Guo’s team has also created metal that reduces the attraction between water molecules and metal molecules, a phenomenon called hydrophobia. Since germs mostly consist of water, it’s all but impossible for them to grow on a hydrophobic surface, says Guo.

Currently, to alter an area of metal the size of a quarter takes 30 minutes or more, but Guo and Vorobyev are working on refining the technique to make it faster. Fortunately, despite the incredible intensity involved, the femtosecond laser can be powered by a simple wall outlet, meaning that when the process is refined, implementing it should be relatively simple.

Guo is also announcing this month in Physical Review Letters a femtosecond laser processing technique that can create incandescent light bulbs that use half as much energy, yet produce the same amount of light. In 2006, Guo’s team used the femtosecond laser to create metal with nanostructures that reflected almost no light at all, and in 2008 the team was able to tune the creation of nanostructures to reflect certain wavelengths of light—in effect turning almost any metal into almost any color.

 

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This research funded by the U.S. Air Force Office of Scientific Research and the National Science Foundation.

April 30, 2009

Electrofluidic Display Technology news

Very interesting news for the future of electronic display.

The release:

Make Brighter, Full-Color Electronic Readers? — Brilliant!

Electrofluidic Display Technology developed at the University of Cincinnati puts electronic book readers ahead by a wide margin.

Thinking about getting an e-reader but not sure if you like reading the dim screen? An international collaboration of the University of Cincinnati, Sun Chemical, Polymer Vision and Gamma Dynamics has announced Electrofluidic Display Technology (EFD), the first technology to electrically switch the appearance of pigments in a manner that provides visual brilliance equal to conventional printed media.

This new entry into the race for full-color electronic paper can potentially provide better than 85 percent “white-state reflectance,” a performance level required for consumers to accept reflective display applications such as e-books, cell-phones and signage.

“If you compare this technology to what’s been developed previously, there’s no comparison,” says developer Jason Heikenfeld, assistant professor of electrical engineering in UC’s College of Engineering. “We’re ahead by a wide margin in critical categories such as brightness, color saturation and video speed.”

This work, which has been underway for several years, has just been published in the paper “Electrofluidic displays using Young–Laplace transposition of brilliant pigment dispersions.

Lead author Heikenfeld explains the primary advantage of the approach.

“The ultimate reflective display would simply place the best colorants used by the printing industry directly beneath the front viewing substrate of a display,” he says. “In our EFD pixels, we are able to hide or reveal colored pigment in a manner that is optically superior to the techniques used in electrowetting, electrophoretic and electrochromic displays.”

Because the optically active layer can be less than 15 microns thick, project partners at PolymerVision see strong potential for rollable displays. The product offerings could be extremely diverse, including electronic windows and tunable color casings on portable electronics.

Furthermore, because three project partners are located in Cincinnati (UC, Sun Chemical, Gamma Dynamics), technology commercialization could lead to creation of numerous high-tech jobs in southwest Ohio.

To expedite commercialization, a new company has been launched: Gamma Dynamics with founding members of this company being John Rudolph as president (formerly of Corning), a world-recognized scientist as CTO (who cannot be announced until July), and Heikenfeld as principal scientist.

“This takes the Amazon Kindle, for example, which is black and white, and could make it full color,” Heikenfeld says. “So now you could take it from a niche product to a mainstream product.”

Funding for this work was provided by Sun Chemical, PolymerVision, the National Science Foundation and the Air Force Research Laboratory.

The pixel structure is able to reveal or hide the pigments with high contrast and video speed. The reservoir (center circle) holds the pigment until it is ready to be displayed by application of voltage. Photo credit: Gamma Dynamics LLC

The pixel structure is able to reveal or hide the pigments with high contrast and video speed. The reservoir (center circle) holds the pigment until it is ready to be displayed by application of voltage. Photo credit: Gamma Dynamics LLC

April 28, 2009

Nanoneedles

Nanotech with a lot of likely bioscience and medical applications.

The release:

Nanoneedle is small in size, but huge in applications

CHAMPAIGN, Ill. — Researchers at the University of Illinois have developed a membrane-penetrating nanoneedle for the targeted delivery of one or more molecules into the cytoplasm or the nucleus of living cells. In addition to ferrying tiny amounts of cargo, the nanoneedle can also be used as an electrochemical probe and as an optical biosensor.

“Nanoneedle-based delivery is a powerful new tool for studying biological processes and biophysical properties at the molecular level inside living cells,” said

Min-Feng Yu, a professor of mechanical science and engineering and corresponding author of a paper accepted for publication in Nano Letters, and posted on the journal’s Web site.

In the paper, Yu and collaborators describe how they deliver, detect and track individual fluorescent quantum dots in a cell’s cytoplasm and nucleus. The quantum dots can be used for studying molecular mechanics and physical properties inside cells.

To create a nanoneedle, the researchers begin with a rigid but resilient boron-nitride nanotube. The nanotube is then attached to one end of a glass pipette for easy handling, and coated with a thin layer of gold. Molecular cargo is then attached to the gold surface via “linker” molecules. When placed in a cell’s cytoplasm or nucleus, the bonds with the linker molecules break, freeing the cargo.

With a diameter of approximately 50 nanometers, the nanoneedle introduces minimal intrusiveness in penetrating cell membranes and accessing the interiors of live cells.

The delivery process can be precisely controlled, monitored and recorded – goals that have not been achieved in prior studies.

“The nanoneedle provides a mechanism by which we can quantitatively examine biological processes occurring within a cell’s nucleus or cytoplasm,” said Yang Xiang, a professor of molecular and integrative physiology and a co-author of the paper. “By studying how individual proteins and molecules of DNA or RNA mobilize, we can better understand how the system functions as a whole.”

The ability to deliver a small number of molecules or nanoparticles into living cells with spatial and temporal precision may make feasible numerous new strategies for biological studies at the single-molecule level, which would otherwise be technically challenging or even impossible, the researchers report.

“Combined with molecular targeting strategies using quantum dots and magnetic nanoparticles as molecular probes, the nanoneedle delivery method can potentially enable the simultaneous observation and manipulation of individual molecules,” said Ning Wang, a professor of mechanical science and engineering and a co-author of the paper.

Beyond delivery, the nanoneedle-based approach can also be extended in many ways for single-cell studies, said Yu, who also is a researcher at the Center for Nanoscale Chemical-Electrical-Mechanical Manufacturing Systems. “Nanoneedles can be used as electrochemical probes and as optical biosensors to study cellular environments, stimulate certain types of biological sequences, and examine the effect of nanoparticles on cellular physiology.”

 

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With Wang, Xiang and Yu, co-authors of the paper are graduate student Kyungsuk Yum and postdoctoral research associate Sungsoo Na. Yu and Wang are affiliated with the university’s Beckman Institute. Wang is also affiliated with the department of bioengineering and with the university’s Micro and Nanotechnology Laboratory.

The Grainger Foundation, National Science Foundation and National Institutes of Health funded the work.

April 23, 2009

Nanotech improves transistor chips

Nanotechnology offers fairly regular breakthroughs in chip tech. Here’s the latest.

The release:

Self-assembled nanowires could make chips smaller and faster

CHAMPAIGN, Ill. — Researchers at the University of Illinois have found a new way to make transistors smaller and faster. The technique uses self-assembled, self-aligned, and defect-free nanowire channels made of gallium arsenide.

In a paper to appear in the IEEE (Institute of Electrical and Electronics Engineers) journal Electron Device Letters, U. of I. electrical and computer engineering professor Xiuling Li and graduate research assistant Seth Fortuna describe the first metal-semiconductor field-effect transistor fabricated with a self-assembled, planar gallium-arsenide nanowire channel.

Nanowires are attractive building blocks for both electronics and photonics applications. Compound semiconductor nanowires, such as gallium arsenide, are especially desirable because of their better transport properties and versatile heterojunctions. However, a number of challenges – including integration with existing microelectronics – must first be overcome.

“Our new planar growth process creates self-aligned, defect-free gallium-arsenide nanowires that could readily be scaled up for manufacturing purposes,” said Li, who also is affiliated with the university’s Micro and Nanoelectronics Laboratory and the Beckman Institute. “It’s a non-lithographic process that can precisely control the nanowire dimension and orientation, yet is compatible with existing circuit design and fabrication technology.”

The gallium-arsenide nanowire channel used in the researchers’ demonstration transistor was grown by metal organic chemical vapor deposition using gold as a catalyst. The rest of the transistor was made with conventional microfabrication techniques.

While the diameter of the transistor’s nanowire channel was approximately 200 nanometers, nanowires with diameters as small as 5 nanometers can be made with the gold-catalyzed growth technique, the researchers report. The self-aligned orientation of the nanowires is determined by the crystal structure of the substrate and certain growth parameters.

In earlier work, Li and Fortuna demonstrated they could grow the nanowires and then transfer-print them on other substrates, including silicon, for heterogeneous integration. “Transferring the self-aligned planar nanowires while maintaining both their position and alignment could enable flexible electronics and photonics at a true nanometer scale,” the researchers wrote in the December 2008 issue of the journal Nano Letters.

In work presented in the current paper, the researchers grew the gallium-arsenide nanowire channel in place, instead of transferring it. In contrast to the common types of non-planar gallium arsenide nanowires, the researchers’ planar nanowire was free from twin defects, which are rotational defects in the crystal structure that decrease the mobility of the charge carriers.

“By replacing the standard channel in a metal-semiconductor field-effect transistor with one of our planar nanowires, we demonstrated that the defect-free nanowire’s electron mobility was indeed as high as the corresponding bulk value,” Fortuna said. “The high electron mobility nanowire channel could lead to smaller, better and faster devices.”

Considering their planar, self-aligned and transferable nature, the nanowire channels could help create higher performance transistors for next-generation integrated circuit applications, Li said.

The high quality planar nanowires can also be used in nano-injection lasers for use in optical communications.

The researchers are also developing new device concepts driven by further engineering of the planar one-dimensional nanostructure.

 

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The work was supported by the National Science Foundation.

April 9, 2009

Diatoms and solar power

Interesting press release from today on the latest in solar power. In other news, get ready for something of a release dump in the next two posts.

The release:

Ancient diatoms lead to new technology for solar energy

CORVALLIS, Ore. – Engineers at Oregon State University have discovered a way to use an ancient life form to create one of the newest technologies for solar energy, in systems that may be surprisingly simple to build compared to existing silicon-based solar cells.

The secret: diatoms.

These tiny, single-celled marine life forms have existed for at least 100 million years and are the basis for much of the life in the oceans, but they also have rigid shells that can be used to create order in a natural way at the extraordinarily small level of nanotechnology.

By using biology instead of conventional semiconductor manufacturing approaches, researchers at OSU and Portland State University have created a new way to make “dye-sensitized” solar cells, in which photons bounce around like they were in a pinball machine, striking these dyes and producing electricity. This technology may be slightly more expensive than some existing approaches to make dye-sensitized solar cells, but can potentially triple the electrical output.

“Most existing solar cell technology is based on silicon and is nearing the limits of what we may be able to accomplish with that,” said Greg Rorrer, an OSU professor of chemical engineering. “There’s an enormous opportunity to develop different types of solar energy technology, and it’s likely that several forms will ultimately all find uses, depending on the situation.”

Dye-sensitized technology, for instance, uses environmentally benign materials and works well in lower light conditions. And the new findings offer advances in manufacturing simplicity and efficiency.

“Dye-sensitized solar cells already exist,” Rorrer said. “What’s different in our approach are the steps we take to make these devices, and the potential improvements they offer.”

The new system is based on living diatoms, which are extremely small, single-celled algae, which already have shells with the nanostructure that is needed. They are allowed to settle on a transparent conductive glass surface, and then the living organic material is removed, leaving behind the tiny skeletons of the diatoms to form a template.

A biological agent is then used to precipitate soluble titanium into very tiny “nanoparticles” of titanium dioxide, creating a thin film that acts as the semiconductor for the dye-sensitized solar cell device. Steps that had been difficult to accomplish with conventional methods have been made easy through the use of these natural biological systems, using simple and inexpensive materials.

“Conventional thin-film, photo-synthesizing dyes also take photons from sunlight and transfer it to titanium dioxide, creating electricity,” Rorrer said. “But in this system the photons bounce around more inside the pores of the diatom shell, making it more efficient.”

The physics of this process, Rorrer said, are not fully understood – but it clearly works. More so than materials in a simple flat layer, the tiny holes in diatom shells appear to increase the interaction between photons and the dye to promote the conversion of light to electricity, and improve energy production in the process.

The insertion of nanoscale tinanium oxide layers into the diatom shell has been reported in ACS Nano, a publication of the American Chemical Society, and the Journal of Materials Research, a publication of the Materials Research Society. The integration of this material into a dye-sensitized solar cell device was also recently described at the fourth annual Greener Nanoscience Conference.

 

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The work is supported by the National Science Foundation and the Safer Nanomaterials and Nanomanufacturing Initiative, a part of the Oregon Nanoscience and Microtechnologies Institute.

Diatoms are ancient, microscopic organisms that are found in the fossil record as far back as the time of the dinosaurs. They are a key part of the marine food chain and help cycle carbon dioxide from the atmosphere.

But in recent years their tiny, silica shells have attracted increasing attention as a way to create structure at the nano level. Nature is the engineer, not high tech tools. This is providing a more efficient, less costly way to produce some of the most advanced materials in the world.

Editor’s Note: The professional publication this story is based on can be found at this URL: http://pubs.acs.org/doi/full/10.1021/nn800470x

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