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Georgia Tech researchers pose with a computer model of graphene oxide’s structure and the chemical species that become part of it. Shown are (l-r, first row) Elisa Riedo and Suenne Kim, (l-r, second row) Angelo Bongiorno, Claire Berger and Si Zhou. Credit: Gary Meek, Georgia Tech.

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Metastable material: Study shows availability of hydrogen controls chemical structure of graphene oxide

A new study shows that the availability of hydrogen plays a significant role in determining the chemical and structural makeup of graphene oxide. The study also found that after the material is produced, its structural and chemical properties continue to evolve for more than a month as a result of continuing chemical reactions with hydrogen. The Georgia Tech researchers began their studies with multilayer epitaxial graphene grown atop a silicon carbide wafer. Their samples included an average of ten layers of graphene. After oxidizing the thin films of graphene using the established Hummers method, the researchers examined their samples using XPS. Over about 35 days, they noticed the number of epoxide functional groups declining while the number of hydroxyl groups increased slightly. After about three months, the ratio of the two groups finally reached equilibrium. “We found that the material changed by itself at room temperature without any external stimulation,” said Suenne Kim, a postdoctoral fellow in Riedo’s laboratory. “The degree to which it was unstable at room temperature was surprising.”

Slip-and-slide power generators

Researchers from Vestfold University College in Norway have created a simple, efficient energy-harvesting device that uses the motion of a single droplet to generate electrical power. The new technology could be used as a power source for low-power portable devices, and would be especially suitable for harvesting energy from low frequency sources such as human body motion, write the authors in a paper accepted to the American Institute of Physics’ journal Applied Physics Letters. The harvester produces power when an electrically conductive droplet (mercury or an ionic liquid) slides along a thin microfabricated material called an electret film, which has a permanent electric charge built into it during deposition. Cyclic tilting of the device causes the droplet to accelerate across the film’s surface; the maximum output voltage (and power) occurs when the sliding droplet reaches its maximum velocity at one end of the film. A prototype of the fluidic energy harvester demonstrated a peak output power at 0.18 microwatts, using a single droplet 1.2 millimeters in diameter sliding along a 2-micrometer-thick electret film.

Reversible doping: Hydrogen flips switch on vanadium oxide

If vanadium oxide had its own TV infomercial, you’d already know: “It’s a metal. It’s an insulator. It’s a window coating and an optical switch.” And thanks to a new study by Rice University physicists - there’s more! The study shows how to reversibly alter VO₂′s quirky electronic properties by treating it with the simplest of substances-hydrogen. When oxygen reacts with vanadium to form VO₂, the atoms form crystals that look like long rectangular boxes. The vanadium atoms line up along the four edges of the box in regularly spaced rows. A single crystal of VO₂ can have many of these boxes lined up side by side, and the crystals conduct electricity like wire as long as they are kept warm. “The weird thing about this material is that if you cool it, when you get to 67°C, it goes through a phase transition that is both electronic and structural. When the phase changes, and these pairings take place, the material changes from being a electrical conductor to an electrical insulator,” says Rice’s Douglas Natelson, lead co-author of the study in this week’s Nature Nanotechnology. In 2010, Natelson and postdoctoral research associate Jiang Wei began to systematically study the phase changes in VO₂. Wei and graduate student Heng Ji began by using a process called vapor deposition to grow VO₂ wires that were about 1,000 times smaller than a human hair. One set of experiments on wires that had been baked in the presence of hydrogen gas returned particularly odd readings. Wei, Ji and Natelson determined that the hydrogen was apparently modifying the VO2 nanowires, but only those in contact with metal electrodes.

Utah-led group gets $15M from Army to design new materials

US soldiers are increasingly weighed down by batteries to power weapons, detection devices and communications equipment. So the Army Research Laboratory has awarded a University of Utah-led consortium almost $15 million to use computer simulations to help design materials for lighter-weight, energy efficient devices and batteries. “We want to help the Army make advances in fundamental research that will lead to better materials to help our soldiers in the field,” says computing Professor Martin Berzins, principal investigator among five University of Utah faculty members who will work on the project. “One of Utah’s main contributions will be the batteries.” Of the five-year Army grant of $14,898,000, the University of Utah will retain $4.2 million for research plus additional administrative costs. The remainder will go to members of the consortium led by the University of Utah, including Boston University, Rensselaer Polytechnic Institute, Pennsylvania State University, Harvard University, Brown University, the University of California, Davis, and the Polytechnic University of Turin, Italy. The new research effort is based on the idea that by using powerful computers to simulate the behavior of materials on multiple scales - from the atomic and molecular nanoscale to the large or “bulk” scale—new, lighter, more energy efficient power supplies and materials can be designed and developed. Improving existing materials also is a goal. ”We want to model everything from the nanoscale to the soldier scale,” Berzins says. “It’s virtual design, in some sense.”

Zinc oxide solar reactor could be a renewable source of hydrogen

Producing hydrogen from non-fossil fuel sources is a problem that continues to elude many scientists but University of Delaware’s Erik Koepf thinks he may have discovered a solution. Koepf, a doctoral candidate in mechanical engineering, has designed a novel reactor that employs highly concentrated sunlight and zinc oxide powder to produce solar hydrogen, a truly clean, sustainable fuel with zero emissions. The reactor, which resembles a large cylinder, is comprised of layers of advanced, ultrahigh temperature insulation and ceramic materials. The conical geometry of the reactor’ design uses gravity to feed zinc oxide powder (the reactant) into the system through 15 hoppers perched on top of the device using special gears and a custom built control assembly Koepf developed at UD. Cooling blocks embedded in the structure keep the motors, a quartz window and the aperture ring, where the sunlight enters, cool. “The idea is to create a small, well-insulated cavity and subject it to highly concentrated sunlight from above,” explains Koepf. Once hot, the hoppers will feed zinc oxide powder (a benign substance resembling baking soda) onto the ceramic layer, causing a reaction that decomposes the powder into pure zinc vapor. In a subsequent step, the zinc will be reacted with water to produce solar hydrogen. “Essentially, we take zinc oxide powder and thermochemically store the energy of the sun in it, then bottle it,” explains Koepf.

Fraunhofer: Feel-good glass for windows

Daylight acts on our body clock and stimulates the brain. Fraunhofer researchers have made use of this knowledge and worked with industry partners to develop a coating for panes of glass that lets through more light. Above all, it promotes the passage through the glass of those wavelengths of light that govern our hormonal balance. Most people prefer to live in homes that are airy and flooded with light. Nobody likes to spend much time in a dark and dingy room. That’s no surprise, since daylight gives us energy and has a major impact on our sense of wellbeing. It is a real mood lifter. Anti-reflective glass that is more transmissive overall to daylight is reserved for certain special applications, such as in glass covers for photovoltaic modules or in glazing for shop windows. The aim with this new kind of glass is to avoid nuisance reflections and to achieve maximum light transmission at the peak emission wavelength of sunlight. This is the wavelength at which the human retina is also most sensitive to light. “However, our biorhythms are not affected by the wavelengths that brighten a room the most, but rather by blue light,” explains graduate engineer Walther Glaubitt, a researcher at the Fraunhofer Institute for Silicate Research ISC in Würzburg. That is why he and his team have developed glass that is designed to be particularly transmissive to light in the blue part of the spectrum. The secret is a special, long-lasting and barely perceptible inorganic coating that is only 0.1 micrometers thick. “Nobody’s ever made glass like this before. It makes you feel as if the window is permanently open,” says Glaubitt. One reason the glass gives this impression is that it exhibits maximum transmission at wavelengths between 450 and 500 nanometers—which is exactly where the effects of blue light are at their strongest.

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Bed made to float with neodymium magnets. Credit: mememetatata; imgur.

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Tiny chip could test for latent TB faster

Biomedical engineers at UC Davis have developed a microfluidic chip to test for latent tuberculosis. They hope the test will be cheaper, faster and more reliable than current testing for the disease. The researchers used a novel approach: They coated a gold wafer with short pieces of a single-stranded DNA segment known to stick specifically to interferon-gamma. They then mounted the wafer in a chip that has tiny channels for blood samples. If interferon-gamma is present in a blood sample, it sticks to the DNA, triggering an electrical signal that can be read by a clinician. The researchers plan to refine the system so that the microfluidic sensor and electronic readout are integrated on a single chip.

How ion bombardment reshapes metal surfaces

To modify a metal surface at the scale of atoms and molecules-for instance to refine the wiring in computer chips or the reflective silver in optical components-manufacturers shower it with ions. While the process may seem high-tech and precise, the technique has been limited by the lack of understanding of the underlying physics. In a new study, Brown University engineers modeled noble gas ion bombardments with unprecedented richness, providing long-sought insights into how it works. The improved understanding could open the door to new technologies, such as new approaches to make flexible electronics, biocompatible surfaces for medical devices, and more damage-tolerant and radiation-resistant surfaces. The new model revealed how ion bombardments can set three main mechanisms into motion in a matter of trillionths of a second. The researchers dubbed the mechanisms “dual layer formation,” “subway-glide mode growth,” and “adatom island eruption.” They are a consequence of how the incoming ions melt the metal and then how it resolidifies with the ions occasionally trapped inside.

Behind the scenes at an LED lighting lab

(GigaOm) “A dozen years ago, people couldn’t spell LED,” recalls Steve Lester, the chief technology officer of LED chip developer Bridgelux, in an interview. But “nobody debates the future of (LED lighting) anymore.” For example, earlier this month at Lightfair International, one of the world’s largest lighting tradeshows, Lester recalls that there was only one booth that featured a non-LED product. While LED lighting has caught on for commercial spaces, like spotlighting merchandise and for outdoor use like street lighting, it has yet to make its presence felt inside homes. That’s mainly because of its high, largely double-digit price tag, which leads to a much longer payback period, considering that consumers don’t keep lights on for as long as businesses do. However, despite a slower adoption by consumers, a McKinsey & Co. report last year projected that LED lighting could make up nearly 60 percent of the total lighting market by 2020.

Demonstration of neodymium magnets strength: How a 19-year-old built a floating bed

(Tecca, via Rare Metal Blog) Those adventurous enough to get quirky furniture for their homes know that they can add a lot of life and sparkle to an otherwise dreary space. Some people with deft hands and imaginative minds even go as far as to make their own. Take for example 19-year-old reddit user mememetatata, who decided one day that he wanted a floating bed… and actually built one using wood and magnets. It took him roughly a grand to buy the necessary materials: 10 puck-sized neodymium magnets—one of the strongest rare-earth magnet variants—priced at $72 each, and $200 to $300 worth of wood. Five of the magnets went inside a thinner, upper wooden panel, and were positioned to repel similar poles of the other five magnets inside a larger base, effectively creating a floating bed.

Obama Administration launches $26M multi-agency competition to strengthen advanced manufacturing clusters across the nation

The administration today announced a $26 million multi-agency Advanced Manufacturing Jobs and Innovation Accelerator Challenge to foster innovation-fueled job creation through public-private partnerships. These coordinated investments will help catalyze and leverage private capital, build an entrepreneurial ecosystem, and promote cluster-based development in regions across the United States. This is the third round of the Jobs Accelerator competition, which is being funded by the Department of Commerce’s Economic Development Administration, NIST, DDE, Department of Labor, the Small Business Administration and the National Science Foundation.

DOE Deputy Secretary announces new steps to support clean energy small businesses

DOE Deputy Secretary Daniel Poneman announced in Fayetteville, Arkansas, $11 million in innovative research and technology grants of up to $150,000 to nearly 70 small businesses nationwide. He also highlighted that over the past year, the agency supported $8 billion in contracts to over 7,000 small businesses. Poneman made the announcements during a tour of Arkansas Power Electronics International, which develops state-of-the-art technology in power storage systems for electric vehicles and other clean energy technologies.

Spacegroup determination using CrystalToolkit

Do you know thatCrystalToolkit has recently been updated to perform spacegroup determination? Now, you can upload a POSCAR or cif of a structure with an unknown spacegroup into CrystalToolkit and the spacegroup will be displayed along with the crystal. This facility works whether the input structure is ordered or disordered. The spacegroup determination capabilities in the Materials Project is built on the excellent spglib written by Atsushi Togo. This code has also been incorporated in the latest version of pymatgen (v1.9.0) and a SymmetryFinder wrapper has been built to allow spglib to work seamlessly with pymatgen’s Structure objects.

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The theme of the second session of the Brown University town meeting on the Materials Genome Initiative was “Materials for energy storage.” The speaker from industry was A123’s principal scientist, Antoni Gozdz, and MIT’s Gerbrand Ceder presented an academic perspective. Ceder was the first to coin the term “materials genome.” Yue Qi, research scientist from General Motors moderated the session. Credit: Brown University; YouTube.

At the end of March, Brown University held a town meeting, which they called “Industry/University Collaborations and the Materials Genome Initiative.” Just this week they uploaded videos of the sessions, which are linked below. The videos are in the range of 30-75 minutes.

The March 29 event was comprised of a plenary address, five topical sessions and a closing panel discussion. Each topical session featured a speaker from industry and one from academia. Each session also had a discussion leader, so presumably, this was intended to be an open conversation about the challenges and progress-to-date on genomic approaches to materials development.

In the opening remarks, Clyde Briant, vice president of research at Brown, says the idea for the conference grew out of a conversation he had with Cyrus Wadia last fall. Brown’s dean of the school of engineering, Larry Larson, succinctly put the MGI into context, saying, “Materials are at the heart of the modern industrial economy.”

Larson shared that meeting the speakers and talking with them, left him “struck by the real breadth of intellectual disciplines that forms the core of materials science,” and specifically mentioned chemistry, physics, energy storage and metallurgy. The five topical sessions reflected the diversity of disciplines that the MGI seeks to corral and the applications that will benefit. They were (with links to video):

• Data management and distribution
• Materials for energy storage
• Materials design for aerospace applications
• Materials design for biomedical applications
• Materials design for automotive applications

The theme of the panel discussion was “Program Agency Visions for the MGI” and was led by Cyrus Wadia from the White House’s OSTP. Panelists included Julie Christodoulou from the Office of Naval Research and Martin Dunn from the National Science Foundation.

Christodoulou was recently appointed a co-deputy chair of the interagency subcommittee, the National Science and Technology Council Subcommittee for the Materials Genome Initiative by the White House Office of Science and Technology Policy. According to an ONR press release, the other co-deputy chairs are Charles Ward from the Air Force Research Laboratory and Ian Robertson of the National Science Foundation. Wadia is the subcommittee’s chairman.

About half of the speakers gave Brown their slide decks, and they can be viewed through links here. I took a peek at Gerbrand Ceder’s presentation (pdf), and it provides a good overview of a genome approach to materials development and what the goals and capabilities of the approach are (or just watch the video above). Halfway through he leads his audience through the example of finding new cathode materials for Li-ion batteries, which he cleverly introduces as “Volta meets Schrödinger: Li-ion Batteries.”

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Stanford University researchers have discovered a new way to ‘decorate’ nanowires with coatings of metal oxide and noble metal nanoparticles that greatly improve surface area. Credit: Stanford Nanocharacterization Lab.

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High-strength silk protein scaffolds for bone repair

(PNAS) Biomaterials for bone tissue regeneration represent a major focus of orthopedic research. However, only a handful of polymeric biomaterials are utilized today because of their failure to address critical issues like compressive strength for load-bearing bone grafts. In this study development of a high compressive strength (~13 MPa hydrated state) polymeric bone composite materials is reported, based on silk protein-protein interfacial bonding. Micron-sized silk fibers (10-600 µm) obtained utilizing alkali hydrolysis were used as reinforcement in a compact fiber composite with tunable compressive strength, surface roughness, and porosity based on the fiber length included. A combination of surface roughness, porosity, and scaffold stiffness favored human bone marrow-derived mesenchymal stem cell differentiation toward bone-like tissue in vitro based on biochemical and gene expression for bone markers. Further, minimal in vivo immunomodulatory responses suggested compatibility of the fabricated silk-fiber-reinforced composite matrices for bone engineering applications.

Prominent electrochromism through vacancy-order melting in a complex oxide

(Nature Communications) Electrochromes are materials that have the ability to reversibly change from one colour state to another with the application of an electric field. Electrochromic colouration efficiency is typically large in organic materials that are not very stable chemically. Here we show that inorganic Bi_0.9Ca_0.1FeO_3-0.05 thin films exhibit a prominent electrochromic effect arising from an intrinsic mechanism due to the melting of oxygen-vacancy ordering and the associated redistribution of carriers. We use a combination of optical characterization techniques in conjunction with high-resolution transmission electron microscopy and first-principles theory. The absorption change and colouration efficiency at the band edge (blue-cyan region) are 4.8×106 m^-1 and 190 cm² C^-1, respectively, which are the highest reported values for inorganic electrochromes, even exceeding values of some organic materials.

Light touch keeps a grip on delicate nanoparticles

(NIST Tech Beat) Using a refined technique for trapping and manipulating nanoparticles, researchers at the National Institute of Standards and Technology have extended the trapped particles’ useful life more than tenfold.* This new approach, which one researcher likens to “attracting moths,” promises to give experimenters the trapping time they need to build nanoscale structures and may open the way to working with nanoparticles inside biological cells without damaging the cells with intense laser light. NIST researchers’ new approach uses a control and feedback system that nudges the nanoparticle only when needed, lowering the average intensity of the beam and increasing the lifetime of the nanoparticle while reducing its tendency to wander.

New method increases the surface area of nanowires by “decorating” them with sinuous chains of metal oxide or noble metal nanoparticles

Though science has known for some time that ornamentation can greatly increase the surface area and alter the surface chemistry of nanowires, engineers at Stanford University have found a more effective method of decorating them that is simpler and faster than previous techniques. The development, say the researchers, might someday lead to better lithium-ion batteries, more efficient thin-film solar cells and improved catalysts that yield new synthetic fuels. The key to the Stanford team’s discovery was a flame. Engineers had long known that nanoparticles could be adhered to nanowires to increase surface area, but the methods for creating them were not very effective in forming the much-desired porous nanoparticle chain structures. Those other methods proved too slow and resulted in a too-dense, thick layer of nanoparticles coating the wires, doing little to increase the surface area. They dipped the nanowires in a solvent-based gel of metal and salt, then air-dried them before applying the flame. In the process, the solvent burns in a few seconds, allowing the all-important nanoparticles to crystalize into branch-like structures fanning out from the nanowires.

Materials Genome and the energy efficient soldier: University of Utah-led group gets $15 million from Army to help design new materials

US soldiers are increasingly weighed down by batteries to power weapons, detection devices and communications equipment. So the Army Research Laboratory has awarded a University of Utah-led consortium almost $15 million to use computer simulations to help design materials for lighter-weight, energy efficient devices and batteries. The consortium includes Boston University, Rensselaer Polytechnic Institute, Pennsylvania State University, Harvard University, Brown University, the University of California, Davis, and the Polytechnic University of Turin, Italy. The Utah-led consortium calls itself Alliance for Computationally-guided Design of Energy Efficient Electronic Materials. The Army says its grant to Utah is for Multiscale Multidisciplinary Modeling of Electronic Materials. “Designing new, transformational materials for our soldiers is the aim of our Enterprise for Multiscale Research of Materials,” says John M. Miller, director of the U.S. Army Research Laboratory. He says a strong foundation for that enterprise will be provided both by the University of Utah-led project, and by a related project led by Johns Hopkins University to understand how materials behave when subjected to high-velocity impacts - work aimed at developing new, lightweight materials to protect U.S. soldiers and vehicles. Miller says funding the research “also shows the Army’s commitment to the national Materials Genome Initiative.” President Barack Obama announced the initiative in June 2011 as a way to speed development and use of new materials.

Fraunhofer Institute for Ceramic Technologies and Systems demonstrates power without the cord

Because of the limited lifespan, battery power is not a feasible option for many applications in the fields of medicine or test engineering, such as implants or probes. Investigators in Germany have now developed a process that supplies these systems with power and without the power cord. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS succeeded in wirelessly transmitting power from a portable transmitter module to a mobile generator module - the receiver. “The cylindrical shaped transfer module is so small and compact that it can be attached to a belt,” says Holger Lausch, scientist at IKTS. The transmitter provides an electric current of over 100 milliwatts and has a range of about 50 centimeters. As a result, the receiver can be placed almost anywhere in the body. “With our portable device, we can remotely supply power to implants, medication dosing systems and other medical applications without touching them - such as ingestible endoscopic capsules that migrate through the gastrointestinal tract and transmit images of the body‘s inside to the outside,” says Lausch. The generator module can be traced any time - regardless of power transfer - with respect to its position and location. So if the generator is located inside a video endoscopy capsule, the images produced can be assigned to specifi c intestinal regions. If it is placed inside a dosing capsule, then the active ingredient in the medication can be released in a targeted manner.

Atomic-scale visualization of electrons confirms theory of iron-based superconductors

Research at Cornell University has for the first time confirmed key theoretical predictions about how iron-based high-temperature superconductors behave. J.C. Séamus Davis, the James Gilbert White Distinguished Professor in the Physical Sciences at Cornell and director of the Center for Emergent Superconductivity at Brookhaven National Laboratory, and colleagues report in the May 4 online edition of the journal Science that they have identified gaps in the energy levels of electrons in an iron-based superconductor that were predicted by leading theories in this new field. The gaps represent electrons that have paired up with twins from adjacent atoms to form so-called “Cooper pairs” that move through the conductor without interference. The research also confirms a prediction that the energy binding the Cooper pairs varies with the direction they take when leaving an atom. Studying crystals of a compound of lithium, iron and arsenic, LiFeAs for short, that becomes a superconductor at 15K (Kelvins, or Celsius degrees above absolute zero), the Cornell researchers found three of the five possible electron bands. “There are two more pairing gaps that we should have been able to detect, and we don’t know yet why not,” Davis said. But finding these three along with the directionality is enough to strongly support the theory, he said, and the measurements give the theorists numbers to plug in to refine and extend their predictions.

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Smart bridge: Iowa State engineers load new bridge with damage-detection gauges

(Newswise) The new bridge over the Iowa River near downtown Iowa Falls is a major upgrade over the 1928 concrete arch structure it replaced last fall, once the longest arch span bridge in the state. The new US Highway 65/Oak Street bridge is stronger. Its foundation is more secure. Its roadway is 18 feet wider. The steel arch maintains some of the aesthetics of the old bridge. And all over the new bridge are gauges, sensors and other technologies installed by Iowa State University researchers that will be used for continuous, real-time monitoring of the structural health, behavior and security of the structure. Those sensors will provide a tremendous amount of quantitative information about the bridge’s performance and condition, says Brent Phares, the interim director of the Bridge Engineering Center. It’s a model that could be used for other new bridges, including much larger ones. Those gauges take 100 readings a second for corrosion, strain, surface conditions, moisture within the steel arch and structure movements over time. The bridge is also equipped to monitor the security of the structure and to record surveillance video

USC researchers develop path to liquid solar cells

Scientists at USC have developed a potential pathway to cheap, stable solar cells made from nanocrystals so small they can exist as a liquid ink and be painted or printed onto clear surfaces. “Like you print a newspaper, you can print solar cells,” says Richard L. Brutchey, assistant professor of chemistry at the USC. Brutchey and USC postdoctoral researcher David H. Webber developed a new surface coating for the nanocrystals, which are made of the semiconductor cadmium selenide. Their research is featured as a “hot article” in Dalton Transactions. Liquid nanocrystal solar cells are cheaper to fabricate than available single-crystal silicon wafer solar cells but are not nearly as efficient at converting sunlight to electricity. Brutchey and Webber solved one of the key problems of liquid solar cells: how to create a stable liquid that also conducts electricity. In the past, organic ligand molecules were attached to the nanocrystals to keep them stable and to prevent them from sticking together. These molecules also insulated the crystals, making the whole thing terrible at conducting electricity.

Improving the efficiency of water splitting in dye-sensitized solar cells by using a biomimetic electron transfer mediator

(PNAS) Although water splitting using semiconductor photoelectrodes has been studied for more than 40 years, it has only recently been demonstrated using dye-sensitized electrodes. The quantum yield for water splitting in these dye-based systems has, so far, been very low because the charge recombination reaction is faster than the catalytic four-electron oxidation of water to oxygen. We show here that the quantum yield is more than doubled by incorporating an electron transfer mediator that is mimetic of the tyrosine-histidine mediator in Photosystem II. The mediator molecule is covalently bound to the water oxidation catalyst, a colloidal iridium oxide particle, and is coadsorbed onto a porous titanium dioxide electrode with a Ruthenium polypyridyl sensitizer. As in the natural photosynthetic system, this molecule mediates electron transfer between a relatively slow metal oxide catalyst that oxidizes water on the millisecond timescale and a dye molecule that is oxidized in a fast light-induced electron transfer reaction. The presence of the mediator molecule in the system results in photoelectrochemical water splitting with an internal quantum efficiency of approximately 2.3% using blue light.

Folding light: Wrinkles and twists boost power from solar panels

Taking their cue from the humble leaf, researchers have used microscopic folds on the surface of photovoltaic material to significantly increase the power output of flexible, low-cost solar cells. The team, led by scientists from Princeton University, reported online April 22 in the journal Nature Photonics that the folds resulted in a 47 percent increase in electricity generation. Yueh-Lin (Lynn) Loo, the principal investigator, said the finely calibrated folds on the surface of the panels channel light waves and increase the photovoltaic material’s exposure to light. “On a flat surface, the light either is absorbed or it bounces back,” said Loo, a professor of chemical and biological engineering at Princeton. “By adding these curves, we create a kind of wave guide. And that leads to a greater chance of the light’s being absorbed.”

NASA flexible aerogel, innovator inducted into Space Technology Hall of Fame

Pioneering work to manufacture composite blankets for space applications has yielded a number of Super-insulating flexible aerogel products for the commercial marketplace. The creation of low-density, light-weight flexible aerogel insulating material was saluted April 19 during Space Technology Hall of Fame ceremonies, held during the Space Foundation’s 28th National Space Symposium. Recognized for their leading aerogel work was James Fesmire, senior principal investigator of the Cryogenics Test Laboratory at NASA’s Kennedy Space Center, and the startup company, Aspen Systems of Marlborough, Mass. There were two key reasons why it has taken decades to realize the commercial potential of aerogel. “First it was so brittle that you could not really make it into a durable product,” said Kang Lee, President and CEO of Aspen Systems. “The second reason is that it was too expensive. My joke is, even if you look at aerogel, it breaks,” Lee said. In tackling those durability and cost issues, Lee said that he and his colleagues applied a multi-disciplinary approach to problem-solving — a mixture of thermal dynamics and acoustics, as well as chemical engineering. “We combined all kinds of disciplines and looked at it with a fresh set of eyes,” Lee said. Taking that approach led to the formation of his company, Aspen Aerogels, to utilize the firm’s patented method to establish an array of industrial, construction, refrigeration, automotive, medical and commercial applications.

Single nanomaterial yields many laser colors

Engineers at Brown University and QD Vision Inc. have created nanoscale single crystals that can produce the red, green, or blue laser light needed in digital displays. The size determines color, but all the pyramid-shaped quantum dots are made the same way of the same elements. In experiments, light amplification required much less power than previous attempts at the technology. The team’s prototypes are the first lasers of their kind. ”Today in order to create a laser display with arbitrary colors, from white to shades of pink or teal, you’d need these three separate material systems to come together in the form of three distinct lasers that in no way shape or form would have anything in common,” said Arto Nurmikko, professor of engineering at Brown University and senior author of a paper describing the innovation in the journal Nature Nanotechnology. The materials in prototype lasers described in the paper are nanometer-sized semiconductor particles called colloidal quantum dots or nanocrystals with an inner core of cadmium and selenium alloy and a coating of zinc, cadmium, and sulfur alloy and a proprietary organic molecular glue. The cladding and the nanocrystal structure are critical advances beyond previous attempts to make lasers with colloidal quantum dots, said lead author Cuong Dang, a senior research associate and nanophotonics laboratory manager in Nurmikko’s group at Brown. Because of their improved quantum mechanical and electrical performance, he said, the coated pyramids require 10 times less pulsed energy or 1,000 times less power to produce laser light than previous attempts at the technology.

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