Researchers solved graphene’s production problems, cleared way for mass production!

When graphene burst onto the scene several years ago, scientists and tech enthusiasts both hailed it as the breakthrough in material engineering that would drive the next generation of semiconductor technology. The truth has been more complicated — for all graphene’s promise, it’s proven more difficult to engineer than many expected. Now, a team of researchers is claiming to have solved some of graphene’s difficult manufacturing problems and believes they can commercialize the approach.

To date, mass manufacturing and defect control have been major issues for all graphene manufacturing, to the point that it’s hampered research simply because getting enough high-quality, defect-free graphene for experimentation is both time consuming and expensive. What this new effort has discovered is a method for creating graphene (the paper actually refers to a “a carbon nanosheet with properties similar to graphene”). The researchers worked with a material they call PIM-1 — a polymer of “intrinsic microporosity. The material was then prepared via spin-coating and heat treatment on a quartz substrate before being used as electrodes within solar cells.

The film is carbonized and transferred to the solar cells. The graphs show that it’s reasonably well distributed

The paper claims that this method of producing carbon nanosheets resulted in solar cells that were 1.922% efficient under 100mW illuminations. That efficiency rating might seem extremely low, but it’s actually in line with organic solar cell capabilities. Organic cells tend to be some of the cheapest solar cells, but the inevitable tradeoff is that they also are extremely inefficient — peak single-junction solar cells can reach 22% efficiency and are already available commercially. It’s not clear if the team’s carbon nanosheet technology is expected to further improve (boosting organic cell efficiency in the process), or if it’s projected to hit the 99.999999% purity required for semiconductor manufacturing. Other techniques, like spraying the graphene directly on a substrate, are still being evaluated for commercial applications. Researchers in Ireland are also exploring a method for reliably producing graphene through the application of Scotch Tape.

The potential for reproducing and adopting these graphene-like carbon nanosheets for other markets is what makes this story interesting. The team didn’t say what percent of the graphene was defect-free, but they do claim that this new manufacturing method is far simpler and less prone to failure than previous types of graphene production. If this technique can be adapted to semiconductors or other types of solar cells, it could be far more useful than any marginal gain in organic solar cell efficiency. According to Dr. Han Ik Joh at the Korean Institute for Science and Technology, graphene can be produced in a similar manner to carbon fiber — and while that’s hardly cheap, it’s still better than our current methods.

Nanogenerator captures energy from walking to recharge wireless gadgets!

By the end of 2014, Earth will be home to more mobile electronic devices than people.

Smartphones, tablets, e-readers, not to mention wearable health and fitness trackers, smart glasses and navigation devices--today's population is more plugged in than ever before.

But our reliance on devices is not problem-free:

Wireless gadgets require regular recharging. While we may think we've cut the cord, we remain reliant on outlets and charging stations to keep our devices up and running. According to a 2009 report by the International Energy Agency (IEA), consumer electronics and information and communication technologies currently account for nearly 15 percent of global residential electricity consumption. What's more, the IEA expects energy consumptions by these devices to double by 2022 and to triple by 2030--thereby slowly but surely adding to the burden on our power infrastructure.

With support from the National Science Foundation, a team of researchers at the Georgia Institute of Technology may have a solution to both problems: They're developing a new, portable, clean energy source that could change the way we power mobile electronics: human motion ("Harvesting Energy from the Natural Vibration of Human Walking").

The triboelectric nanogenerator (TENG) is made from thin, lightweight plastic sheets, interlocked in a rhombic grid. As the wearer walks, the rhythmic movement that occurs as his/her weight shifts from side to side causes the inside surfaces of the plastic sheets to touch and then separate, touch and then separate. The periodic contact and separation drives electrons back and forth, producing an alternating electric current. This process, known as the triboelectrification effect, also underlies static electricity. The key to the new technology is the addition of highly charged nanomaterials that maximize the contact between the two surfaces, pumping up the energy output of the TENG. (Image: Zhong Lin Wang, Georgia Tech)

Led by material scientist Zhong Lin Wang, the team has created a backpack that captures mechanical energy from the natural vibration of human walking and converts it into electrical energy. This technology could revolutionize the way we charge small electronic devices, and thereby reduce the burden of these devices on non-renewable power sources and untether users from fixed charging stations.

Smaller, lighter, more energy efficient

Wearable generators that convert energy from the body's mechanical potential into electricity are not new, but traditional technologies rely on bulky or fragile materials. By contrast, Wang's backpack contains a device made from thin, lightweight plastic sheets, interlocked in a rhombic grid. (Think of the collapsible cardboard containers that separate a six pack of fancy soda bottles.)

As the wearer walks, the rhythmic movement that occurs as his/her weight shifts from side to side causes the inside surfaces of the plastic sheets to touch and then separate, touch and then separate. The periodic contact and separation drives electrons back and forth, producing an alternating electric current. This process, known as the triboelectrification effect, also underlies static electricity, a phenomenon familiar to anyone who has ever pulled a freshly laundered fleece jacket over his or her head in January.

But the key to Wang's technology is the addition of highly charged nanomaterials that maximize the contact between the two surfaces, pumping up the energy output of what Wang calls the triboelectric nanogenerator (TENG).

"The TENG is as efficient as the best electromagnetic generator, and is lighter and smaller than any other electric generators for mechanical energy conversion," says Wang. "The efficiency will only improve with the invention of new advanced materials."

Charging on the go

In the laboratory, Wang's team showed that natural human walking with a load of 2 kilograms, about the weight of a 2-liter bottle of soda, generated enough power to simultaneously light more than 40 commercial LEDs (which are the most efficient lights available).

Wang says that the maximum power output depends on the density of the surface electrostatic charge, but that the backpack will likely be able to generate between 2 and 5 watts of energy as the wearer walks--enough to charge a cell phone or other small electronic device.

The researchers anticipate that this will be welcome news to outdoor enthusiasts, field engineers, military personnel and emergency responders who work in remote areas.

As far as Wang and his colleagues are concerned however, human motion is only one potential source for clean and renewable energy. In 2013, the team demonstrated that it was possible to use TENGs to extract energy from ocean waves.

Source: National Science Foundation

Nano engineers develop next-generation battery!

A research team from the University of Alberta has used carbon nanomaterials to develop next-generation batteries capable of charging faster and lasting longer than today’s standard lithium-ion batteries.

“What we’ve done is develop a new electrochemistry technology that can provide high energy density and high power density for the next generation,” said lead researcher Xinwei Cui, who completed his PhD in materials engineering at the U of A in 2010 and is now chief technology officer at AdvEn Solutions, a technology development company that is working on the battery so it can be commercially manufactured for use in electronic devices.

Xinwei Cui holds one of the nano-engineered carbon components of the new battery technology.

The research team developed the new technology for energy storage using a process called induced fluorination.

“We tried lots of different materials. Normally carbon is used as the anode in lithium-ion batteries, but we used carbon as the cathode, and this is used to build a battery with induced fluorination,” Cui explained.

The advantages of using carbon are that it is cost-effective and safe to use, and the energy output is five to eight times higher than lithium-ion batteries currently on the market. The new battery also performs better than two other future technologies: lithium-sulfur batteries, currently in the prototype stage, and lithium-air batteries, now under development. For example, the induced-fluorination technology could be used to produce cellphone batteries that would charge faster and last longer.

“Nobody knew that carbon could be used as a cathode with such a high performance. That is what’s unique with our technology and what is detailed in our paper,” Cui said.

The team published their findings in the journal Nature Scientific Reports ("Rechargeable Batteries with High Energy Storage Activated by In-situ Induced Fluorination of Carbon Nanotube Cathode"). The paper was written by Cui; Jian Chen, a researcher in the National Institute for Nanotechnology; Tianfei Wang, a PhD candidate in materials engineering; and Weixing Chen, professor of chemical and materials engineering at the U of A.

“It wasn’t a quick process. Once we found carbon is different, we persisted for three years until we got results,” Cui said.

AdvEn Solutions hopes to have a prototype by the end of 2014 and aims to develop three versions of the battery to serve different goals. One battery would have a high power output and a long life cycle, the second would have high energy for quick charging, and the third a super-high energy storage.

“We have a long way to go, but we’re on the right track. It’s exciting work and we want everyone to know about it and that it’s very young but promising,” said Cui.

Source: By Nicole Basaraba, University of Alberta

Nanotechnology adds bling to antibacterials!

Bacteria love to colonize surfaces inside your body, but they have a hard time getting past your rugged, salty skin. Surgeries to implant medical devices often give such bacteria the opportunity needed to gain entry into the body cavity, allowing the implants themselves to act then as an ideal growing surface for biofilms.

A group of researchers at the Shanghai Institute of Ceramics in the Chinese Academy of Sciences are looking to combat these dangerous sub-dermal infections by upgrading your new hip or kneecap in a fashion appreciated since ancient times – adding gold. They describe the results of tests with a new antibacterial material they developed based on gold nanoparticles in the journal Applied Physics Letters ("Plasmonic gold nanoparticles modified titania nanotubes for antibacterial application").

Destructive electron extraction from bacterial membranes by plasmonic gold nanoparticles. (Image: Jinhua Li/SICCAS)

"Implant-associated infections have become a stubborn issue that often causes surgery failure," said Xuanyong Liu, the team's primary investigator at the Shanghai Institute of Ceramics. Designing implants that can kill bacteria while supporting bone growth, Liu said, is an efficient way to enhance in vivo osteointegration.

Titanium dioxide is able to kill bacteria itself due to its properties as a photocatalyst. When the metal is exposed to light, it becomes energetically excited by absorbing photons. This generates electron-hole pairs, turning titania into a potent electron acceptor that can destabilize cellular membrane processes by usurping their electron transport chain's terminal acceptor. The membrane is gradually destabilized by this thievery, causing the cell to leak out until it dies.

The dark conditions inside the human body, however, limit the bacteria-killing efficacy of titanium dioxide. Gold nanoparticles, though, can continue to act as anti-bacterial terminal electron acceptors under darkness, due to a phenomenon called localized surface plasmon resonance. Surface plasmons are collective oscillations of electrons that occur at the interface between conductors and dielectrics – such as between gold and titanium dioxide. The localized electron oscillations at the nanoscale cause the gold nanoparticles to become excited and pass electrons to the titanium dioxide surface, thus allowing the particles to become electron acceptors.

Liu and his team electrochemically anodized titanium to form titanium dioxide nanotube arrays, and then further deposited the arrays with gold nanoparticles in a process called magnetron sputtering. The researchers then allowed Staphylococcus aureus and Escherichia coli to grow separately on the arrays -- both organisms were highly unsuccessful, exhibiting profuse membrane damage and cell leakage.

While silver nanoparticles have been previously explored as an antibacterial agent for in vivo transplants, they cause significant side effects such as cytotoxicity and organ damage, whereas gold is far more chemically stable, and thus more biocompatible.

"The findings may open up new insights for the better designing of noble metal nanoparticles-based antibacterial applications," Liu said.

Further research for Liu and his colleagues includes expanding the scope of experimental bacteria used and evaluating the arrays' in vivo efficacy in bone growth and integration.

Source: American Institute of Physics

Transparent and flexible carbon nano tube and IGZO chip!

Researchers at the University of Southern California (USC) have combined two of our favorite materials — carbon nanotubes and IGZO — to create a new hybrid computer chip design that is flexible, transparent, and more energy efficient than conventional silicon chips. Potential applications include flexible OLED displays, circuits, memory, and sensors, eventually leading towards flexible, wearable computers — which, as you may have noticed, appears to be the direction that the computing industry is moving towards.

Carbon nanotubes (CNTs), as we reported on last week, are creeping ever closer to becoming a viable replacement to silicon in field-effect transistors (FETs). Transistors fashioned out of CNTs are much smaller than their silicon counterparts, and thus could enable the reinstatement of Moore’s law. IGZO (indium, gallium, zinc oxide) is a mature semiconductor that’s used in modern thin-panel (LCD and OLED) displays. IGZO’s main advantage is that it’s transparent. CNTs are flexible and transparent, too.

Both materials are theoretically very powerful — but so far, while it’s been easy enough to make p-type CNT transistors and n-type IGZO transistors, the inverse (n-type CNT, p-type IGZO) has proven hard to crack, making it impossible to create a single chip out of CNTs or IGZO. Instead of trying to force the matter, Chongwu Zhou and colleagues at USC decided on an alternate approach: a hybrid circuit design that uses p-type CNT transistors and n-type IGZO transistors. ["Large-scale complementary macroelectronics using hybrid integration of carbon nanotubes and IGZO thin-film transistors"]

IGZO/CNT hybrid circuit, under a micrograph (in this case, a 51-stage ring oscillator)

This novel hybridization works a bit like a metal alloy: The strengths of the two materials shine through, while their weaknesses are mitigated. In this case, the CNT-IGZO hybrid circuit reduces power loss and increases efficiency. When the transistors are built on a polymer substrate, the whole thing is flexible, too. So far, the researchers have managed to build a circuit consisting of 1,000 hybrid transistors — not bad, but obviously a long way to go. (That’s one of the main barriers to the deployment of new, non-silicon materials: Developing the tools and processes that can accurately and reliably create billions of transistors on a substrate the size of your fingernail.)

In terms of electrical characteristics, the hybrid chips appear to tick all the right boxes. Electron mobility, drain current, and on/off ratio all seem to be pretty good. The next step, as always, is for the USC researchers to build more complicated circuits using their hybrid integration approach, as well as improving fabrication on flexible substrates — which then leads into wearable computers and other similar applications.

Speaking to Kurzweil AI, one of the researchers said the technology “may become sufficiently mature and be commercialized in ten years” — which might sound like a long time, but in the world of nanoelectronics and oxide layer thicknesses measured in atoms, it’s fairly reasonable.

Nanofibers for quantum computing!

Take a fine strand of silica fiber, attach it at each end to a slow-turning motor, gently torture it over an unflickering flame until it just about reaches its melting point and then pull it apart. The middle will thin out like a piece of taffy until it is less than half a micron across -- about 200 times thinner than a human hair.

That, according to researchers at the Joint Quantum Institute at the University of Maryland, is how you fabricate ultrahigh transmission optical nanofibers, a potential component for future quantum information devices, which they describe in AIP Advances ("Ultrahigh transmission optical nanofibers").

Light propagating through an optical nanofiber during the pulling process with a SEM image of the 536 nanometer diameter waist.

Quantum computers promise enormous power, but are notoriously tricky to build. To encode information in qubits, the fundamental units of a quantum computer, the bits must be held in a precarious position called a superposition of states. In this fragile condition the bits exist in all of their possible configurations at the same time, meaning they can perform multiple parallel calculations.

The tendency of qubits to lose their superposition state too quickly, a phenomenon known as decoherence, is a major obstacle to the further development of quantum computers and any device dependent on superpositions. To address this challenge, researchers at the Joint Quantum Institute proposed a hybrid quantum processor that uses trapped atoms as the memory and superconducting qubits as the processor, as atoms demonstrate relatively long superposition survival times and superconducting qubits perform operations quickly.

“The idea is that we can get the best of both worlds,” said Jonathan Hoffman, a graduate student in the Joint Quantum Institute who works in the lab of principal investigators Steven Rolston and Luis Orozco. However, a problem is that superconductors don’t like high optical power or magnetic fields and most atomic traps use both, Hoffman said.

This is where the optical nanofibers come in: The Joint Quantum Institute team realized that nanofibers could create optics-based, low-power atom traps that would “play nice” with superconductors. Because the diameter of the fibers is so minute -- 530 nanometers, less than the wavelength of light used to trap atoms -- some of the light leaks outside of the fiber as a so-called evanescent wave, which can be used to trap atoms a few hundred nanometers from the fiber surface.

Hoffman and his colleagues have worked on optical nanofiber atom traps for the past few years. Their AIP Advances paper describes a new procedure they developed that maximizes the efficiency of the traps through careful and precise fabrication methods.

The group’s procedure, which yields an improvement of two orders of magnitude less transmission loss than previous work, focuses on intensive preparation and cleaning of the pre-pulling environment the nanofibers are created in.

In the fabrication process, the fiber is brushed through the flame to prevent the formation of air currents, which can cause inconsistencies in diameter to arise, as it is pulled apart and tapered down. The flame source is a mixture of hydrogen and oxygen gas in a precise two-to-one ratio, to ensure that water vapor is the only byproduct. The motors are controlled by an algorithm based on the existing work of a group in Vienna, which calculates the trajectories of the motors to produce a fiber of the desired length and profile.

Previous pulling methods, such as carbon dioxide lasing and chemical etching, were limited by the laser’s insufficient diameter and by a lesser degree of control over tapering length, respectively.

Future work includes interfacing the trapped atoms with the superconducting circuits held at 10 mKelvin in a dilution refrigerator, as well as guiding more complicated optical field patterns through the fiber (higher-order modes) and using these to trap atoms.

Source: American Institute of Physics

Solar cells -powered by nanoholes!

Increasing the cost-effectiveness of photovoltaic devices is critical to making these renewable energy sources competitive with traditional fossil fuels. One possibility is to use hybrid solar cells that combine silicon nanowires with low-cost, photoresponsive polymers. The high surface area and confined nature of nanowires allows them to trap significant amounts of light for solar cell operations. Unfortunately, these thin, needle-like structures are very fragile and tend to stick together when the wires become too long.

Now, findings by Xincai Wang from the A*STAR Singapore Institute of Manufacturing Technology and co-workers from Nanyang Technological University could turn the tables on silicon nanowires by improving the manufacturing of silicon ‘nanoholes’ — narrow cavities carved into silicon wafers that have enhanced mechanical and light-harvesting capabilities ("High efficiency silicon nanohole/organic heterojunction hybrid solar cell").

A straightforward procedure that transforms silver nanospheres (top) into silicon nanoholes (bottom) can overcome the shortcomings of nanowire-based solar cells. (© AIP)

Nanoholes are particularly effective at capturing light because photons can ricochet many times inside these openings until absorption occurs. Yet a practical understanding of how to fabricate these tiny structures is still lacking. One significant problem, notes Wang, is control of the initial stages of nanohole formation — a crucial period that can often induce defects into the solar cell.

Instead of traditional time-consuming lithography, the researchers identified a rapid, ‘maskless’ approach to producing nanoholes using silver nanoparticles. First, they deposited a nanometer-thin layer of silver onto a silicon wafer which they toughened by annealing it using a rapid-burst ultraviolet laser. Careful optimization of this procedure yielded regular arrays of silver nanospheres on top of the silicon surface, with sphere size and distribution controlled by the laser annealing conditions.

Next, the nanosphere–silicon complex was immersed into a solution of hydrogen peroxide and hydrofluoric acid — a mixture that eats away at silicon atoms directly underneath the catalytic silver nanospheres. Subsequent removal of the silver particles with acid produced the final, nanohole-infused silicon surface (see image).

The team analyzed the solar cell activity of their nanohole interfaces by coating them with a semiconducting polymer and metal electrodes. Their experiments revealed a remarkable dependence on nanohole depth: cavities deeper than one micrometer showed sharp drops in power conversion efficiency from a maximum of 8.3 per cent due to light scattering off of rougher surfaces and higher series resistance effects.

“Our simple process for making hybrid silicon nanohole devices can successfully reduce the fabrication costs which impede the solar cell industry,” says Wang. “In addition, this approach can be easily transferred to silicon thin films to develop thin-film silicon–polymer hybrid solar cells with even higher efficiency.”

Source: A*STAR

Using sand to improve battery performance!

Researchers at the University of California, Riverside’s Bourns College of Engineering have created a lithium ion battery that outperforms the current industry standard by three times. The key material: sand. Yes, sand.

“This is the holy grail – a low cost, non-toxic, environmentally friendly way to produce high performance lithium ion battery anodes,” said Zachary Favors, a graduate student working with Cengiz and Mihri Ozkan, both engineering professors at UC Riverside.

The idea came to Favors six months ago. He was relaxing on the beach after surfing in San Clemente, Calif. when he picked up some sand, took a close look at it and saw it was made up primarily of quartz, or silicon dioxide.

His research is centered on building better lithium ion batteries, primarily for personal electronics and electric vehicles. He is focused on the anode, or negative side of the battery. Graphite is the current standard material for the anode, but as electronics have become more powerful graphite’s ability to be improved has been virtually tapped out.

From left, (b) unpurified sand, (c) purified sand, and (d) vials of unpurified sand, purified sand, and nano silicon.

Researchers are now focused on using silicon at the nanoscale, or billionths of a meter, level as a replacement for graphite. The problem with nanoscale silicon is that it degrades quickly and is hard to produce in large quantities.

Favors set out to solve both these problems. He researched sand to find a spot in the United States where it is found with a high percentage of quartz. That took him to the Cedar Creek Reservoir, east of Dallas, where he grew up.

Sand in hand, he came back to the lab at UC Riverside and milled it down to the nanometer scale, followed by a series of purification steps changing its color from brown to bright white, similar in color and texture to powdered sugar.

After that, he ground salt and magnesium, both very common elements found dissolved in sea water into the purified quartz. The resulting powder was then heated. With the salt acting as a heat absorber, the magnesium worked to remove the oxygen from the quartz, resulting in pure silicon.

The Ozkan team was pleased with how the process went. And they also encountered an added positive surprise. The pure nano-silicon formed in a very porous 3-D silicon sponge like consistency. That porosity has proved to be the key to improving the performance of the batteries built with the nano-silicon.

Schematic showing how sand is turned into pure nano-silicon.

The improved performance could mean expanding the expected lifespan of silicon-based electric vehicle batteries up to 3 times or more, which would be significant for consumers, considering replacement batteries cost thousands of dollars. For cell phones or tablets, it could mean having to recharge every three days, instead of every day.

The findings were just published in a paper, “Scalable Synthesis of Nano-Silicon from Beach Sand for Long Cycle Life Li-ion Batteries” in the journal Nature Scientific Reports. In addition to Favors and the Ozkan’s, authors were: Wei Wang, Hamed Hosseini Bay, Zafer Mutlu, Kazi Ahmed and Chueh Liu. All five are graduate students working in the Ozkan’s labs.

Now, the Ozkan team is trying to produce larger quantities of the nano-silicon beach sand and is planning to move from coin-size batteries to pouch-size batteries that are used in cell phones.

Source: By Sean Nealon, University of California, Riverside

Nanoparticle-membrane interactions to determine safety!

Sometimes breakthrough materials with important benefits to society pose environmental risks that aren't apparent until decades later. In the growing field of nanotechnology--the creation of materials or processes at the nano-scale--researchers are trying to identify potential hazards before new products are in widespread use.

"Too often in the past we don't know whether something will become a risk until it's too late and it's already out there," says Geoffrey Bothun, an associate professor of chemical engineering at the University of Rhode Island. "Rather than create products with nanomaterials in them and simply releasing them into the marketplace, the field wants to get a better handle on what sort of environmental or safety risks are associated with these materials."

Nanotechnology offers the potential for many new applications in medicine, electronics, energy and biomaterials but, like any new technology, it also raises concerns about possible toxicity to humans and the environment from long-term exposure.

"There is a lot of excitement over what nanotechnology can do for job creation, new product development and better materials," Bothun says. "It's thought to be the new industrial revolution. But scientists, engineers and policy makers want to get ahead of the game and guide the design of the best materials with the least environmental impact."

The National Science Foundation (NSF)-funded scientist specifically is studying how engineered nanoparticles bind to cell membranes, and the impact of the process on the membrane itself ("Nanoparticle-Bacterial Membrane Interactions and their Role in Nanotoxicology").

A transmission electron microscopy image of an iron oxide nanoparticle (black) binding to an oppositely charged model cell membrane (phospholipid bilayer). The membrane is in the form of a spherical vesicle dispersed in water. Adhesion between the nanoparticle and the membrane drive the deformation of the vesicle shape. (Image: Geoff Bothun, Chemical Engineering, University of Rhode Island)

"We don't know enough about how these physical interactions are taking place, and to what degree they contribute to toxicity," he says. "Nanoparticles can and do inhibit or kill cells. In some cases, that's what they are supposed to do. For example, there are a lot of natural antimicrobial molecules that bind to a membrane, disrupt it and break holes, leading to cell death."

Nanoparticles exist in many products that come into close contact with humans, among them, clothing, medicine, cosmetics and sunscreen.

"Silver nanoparticles, for example, are in hunting gear and athletic clothing and act almost like an antibiotic," Bothun says. "They kill bacteria that cause stinkiness largely by releasing silver ions. We're exposed to this silver all the time, but whether or not it is dangerous is somewhat unknown."

His research goal is to learn enough about what happens in nanoparticle-membrane interactions to allow experts to use this information in predicting whether the particles will prove toxic. "If we understand the mechanisms behind how these particles stick to cells, that should help us design particles that could selectively bind to, for example, bacteria and not human cells," he says.

Bothun is conducting his research under an NSF Faculty Early Career Development (CAREER) award, which he received in 2011. The award supports junior faculty who exemplify the role of teacher-scholars through outstanding research, excellent education, and the integration of education and research within the context of the mission of their organization.

He and his team use transmission electron microscopy (TEM) to study synthetic bacterial cell membranes they create and then expose to different types of nanoparticles. "We can change the membrane composition, and nanoparticle type and composition and size," he says. "We've got a lot of variables we can play with on both sides. With TEM we can directly image nanoparticle membrane binding and changes that occur in the membrane as a result of this binding."

They already have determined that nanoparticles can behave like proteins, "meaning that we can use some of our existing knowledge and technologies on protein interactions to help understand and predict nanoparticle interactions," he says. "For example, there are cases where hydrophobic (water hating) nanoparticles can change cell membrane structure similar to hydrophobic proteins."

As part of the grant's educational component, the scientists have enhanced a freshman general education course at the university with the goal of educating students about the social, economic and environmental impacts of nanotechnology, as well as the need to effectively communicate emerging technologies to broad audiences. They also plan to sponsor professional development activities, including research and specialized workshops, to supplement the curriculum.

Finally, they are developing a new high school program, "Think Small/Dream Big!" for science classes in urban schools in the greater Providence area. Students will work with the transmission electron microscope, analyzing nanomaterials using state-of-the-art instrumentation.

"The goal here is to inform and excite high school students about nanotechnology, and all of the STEM (science, technology, engineering and mathematics) fields, and to show them how nanotechnology will have an impact on their lives in the future and the role they can play," Bothun says.

Source: By Marlene Cimons, National Science Foundation

Nano implications for fine tuning graphene and nanotubes!

Researchers at the Department of Energy’s Lawrence Berkeley National Lab (Berkeley Lab) and the University of Hawaii have uncovered the first step in the process that transforms gas-phase molecules into solid particles like soot and other carbon-based compounds.

The finding could help combustion chemists make more-efficient, less-polluting fuels and help materials scientists fine-tune their carbon nanotubes and graphene sheets for faster, smaller electronics. In addition, the results could have implications for the burgeoning field of astrochemistry, potentially establishing the chemical process for how gaseous outflows from stars turn into carbon-based matter in space.

“When you burn a flame, you start with a gas-phase reactant and then analyze the products, which include soot,” says Musahid Ahmed, scientist in the Chemical Sciences Division at Berkeley Lab. “But there is no direct evidence for the chemical bonds that break and form in the process.” For more than 30 years, scientists have developed computational models of combustion to explain how gas molecules form soot, but now Ahmed and his colleagues have data to confirm one long-standing theory in particular. “Our paper presents the first direct observation of this process,” he says.

Graphical representation of the chemistry in the early stages of soot formation. The mechanism to the right was demonstrated by experiment, while the one on the left was not. (Image: Dorian Parker, University of Hawaii)

While the research is relevant to a number of disciplines—combustion science, materials science, and astrochemistry—it’s combustion science that could see the most direct impact the soonest, says Ahmed. Specifically, the fundamental chemistry discovery could be used to find or design fuels that burn cleaner and don’t produce as much soot.

Think about your car engine. If the combustion process were perfect, only carbon dioxide and water would come out of the tailpipe. Instead, we see fumes and particulates like soot, a visible macromolecule made up of sheets of carbon.

Theoretically, there are hundreds of different ways molecules can combine to create these dirty emissions. But there has been one popular class of mechanisms that outlines possible early steps for bond making and bond breaking during combustion. Called hydrogen abstraction-acetylene addition, or HACA, it was developed by Michael Frenklach professor of mechanical engineering at the University of California Berkeley in 1991.

One version of HACA works like this: during the high-temperature, high-pressure environment of combustion, a simple ring of six carbon and six hydrogen atoms, called benzene, would lose one of its hydrogen atoms, allowing another two-carbon molecule called acetylene, to attach to the ring, giving it a kind of tail. Then the acetylene tail would lose one of its hydrogen atoms so another acetylene could link up in, doubling the carbon atoms in the tail to four.

Next, the tail would curl around and attach to the original ring, creating a double-ring structure called naphthalene. Link by link, ring by ring, these molecules would continue to grow in an unwieldy, crumpled way until they became the macromolecules that we recognize as soot.

To test the first step of the theoretical HACA mechanism, Ahmed and collaborators from the University of Hawaii used a beamline at the Advanced Light Source (ALS) at Berkeley Lab specifically outfitted to study chemical dynamics. The ALS, a DOE Office of Science user facility, produces numerous photons over a wide range of energies, allowing researchers to probe a variety of molecules produced in this chemical reaction with specialized mass spectrometry analysis.

Unique to this experimental setup, Ahmed’s team used a so-called hot nozzle, which recreates combustion environment in terms of pressure and temperature. The group started with a gaseous mix of nitrosobenzene (a benzene ring with a molecule of nitrogen and oxygen attached) and acetylene, and pumped it through a heated tube at a pressure of about 300 torr and a temperature of about 750 degrees Celsius. The molecules that came out the other end were immediately skimmed into a mass spectrometer that made use of the synchrotron light for analysis.

The researchers found two molecules predominantly emerged from the process. The more abundant kind was the carbon ring with a short acetylene tail on it, called phenylacetylene. But they also saw evidence for the double ring, naphthalene. These results, says Ahmed, effectively rule out one HACA mechanism—that a carbon ring would gain two separate tails and those tails would bond to form the double ring—and confirm the most popular HACA mechanism where a long tail curls around to form naphthalene.

Ahmed’s local team included Tyler Troy, postdoctoral fellow at Berkeley Lab, and this work was performed with long-term collaborator Ralf Kaiser, professor of physical chemistry at the University of Hawaii at Manoa, and Dorian Parker, postdoctoral fellow also at Hawaii. The research was published June 20 online in the journal Angewandte Chemie ("Hydrogen Abstraction–Acetylene Addition Revealed").

“Having established the route to naphthalene, the simplest polycyclic aromatic hydrocarbon, the next step will be to unravel the pathways to more complex systems,” says Kaiser.

Further experiments will investigate these follow-up mechanisms. It’s a tricky feat, explains Ahmed, because the molecular possibilities quickly multiply. The researchers will add infrared spectroscopy to their analysis in order to catch the variety of molecules that form during these next phases of combustion.

Source: Oregon State University

IBM betting carbon nanotubes can restore Moore’s Law by 2020!

The ongoing collapse of Moore’s Law is one of the least reported stories in technology today. That old canard says that the number of transistors that’s possible to fit onto a chip will double every two years. Like a shark, our processing industry can only survive in its current form thanks to that constant forward motion — and with the rate of semiconductor advance now slowing, the industry could well slow down with it. Silicon is, at this point, totally incapable of providing any further advancement; a new material is needed, one that can be reliably laid down at scales well below 10 nanometers. For a long time, experts have argued that carbon nanotubes (CNTs) are the most likely answer, and this week IBM announced it expects to have a commercial CNT chip ready by the year 2020.

When it comes to computer chips, size is everything. Our devices, be they smartphones or desktop towers, present a hard physical limit on space; so long as we are still switching physical transistors on and off to do computation, making devices faster means packing more transistors into the same physical space. Engineers have spent the last decade or so forecasting the end of silicon as a metal that could support much further miniaturization; its properties make it inherently difficult to lay down at the scales we’re beginning to require. But carbon nanotubes are just rolled up tubes of graphene, which is only a single atom thick; though engineers have been talking bout graphene as the future of transistors for a while now, IBM is the first to really put itself out there on the issue.

A carbon nanotube.

The first CNT transistors were built in the late 1990′s but since then we’ve made little progress in creating chips with billions of those transistors packed densely and — above all — affordably. IBM has already demonstrated the ability to create processors with about 10,000 transistors, but that’s still a long, long way off what we’ll need. The manufacturing process they’ve chosen for this project sees units of six CNTs acting as each transistor. They’re about 30 nanometers long and 1.4 wide, spaced eight nanometers apart — given their calculations, a CNT processor could be six times faster than a modern silicon chip for the same power draw.

The problem is the same as it’s ever been: it’s mechanically very difficult to pack things that closely together without losing quality and accuracy in manufacturing. One possible solution is to use labelled transistors that can be laid down at one scale but which will then self-assemble to pack even more tightly. It would be gut-punchingly expensive to replace all the manufacturing infrastructure that exists around making silicon chips, so much of the funding these days goes to finding ways old manufacturing tech could produce new chip tech.

It’s unclear whether IBM has made a specific breakthrough that led it to this announcement or just a general feeling of progress and meaningful forward movement. Either way, the company is upfront about the fact that if CNT computers don’t manage to make some sort of move by around the year 2020, the window of opportunity may close. Potentially competing technologies are also under development, from quantum computers to optical computers and beyond, and their potential to increase computational power is far greater than CNTs.

Still, carbon nanotubes, and their sister-material graphene, are by far the most likely candidate to replace silicon in the short term. If we don’t have a fundamentally different sort of chip design by the year 2020, we could see the computer hardware industry slow down markedly. And if even the computer business can’t thrive in the new economy, then there it’s official: in the new economy, there is absolutely no such thing as a safe bet.

Nanotechnology researchers develop bionic emulation of a billions of years old biological transportation system!

For billions of years, bacteria move along using cilia. These propeling organelles are ubiquitous and they are even found in almost any human cell. Following the natural paragon scientists at the Kiel University constructed molecules that imitate these tiny, hair-like structures. Autonomously moving artificial organelles and a more efficient production of chemical compounds might now be within reach. The researchers recently published their results in the scientific journal European Journal of Organic Chemistry ("Diazocines on Molecular Platforms").

Artistic depiction of paramecia with artificial cilia: Chiral, unidirectional molecular switches mounted on surfaces are the prerequisite for inducing cilia driven directed motion. Scientists from Kiel transformed simple azobenzenes to chiral switches equipped with a molecular platform to mount them on gold surfaces. This bionic emulation of a billions of years old biological transportation system might be used in nano fabrication in the future. (Illustration: Herges)

Cilia, or ciliated epithelia, cover our respiratory tract like a lawn. In our pharynx and nasal mucosa they are responsible for continuously transporting mucus and particles embedded therein towards our throat. (except for heavy smokers, whose cilia where destroyed by nicotine and tar.) Tobias Tellkamp and Professor Rainer Herges have now come one step closer to their aim of artificially reproducing this biological transport system with switchable molecules.

Molecules that wiggle when exposed to light are known for a long time. But directed movement had not been possible up until now because back and forth movement cancel each other. To achieve a net displacement, the cilia should beat only to one side. Applying a trick within the molecular construction, the chemists of Kiel University’s Collaborative Research Centre 677 "Function by Switching" solved this problem: Moreover, to get those molecular cilia up and running, the scientists fixed them on a surface. “We attached a kind of molecular suction cup onto the switches”, project leader Herges explains.

Studies have shown that this suction cup adheres very well to gold surfaces. The team of scientists observed that the molecules self-assemble autonomously on the surface, densely packed, side by side like oranges on a shelf. “The suction cups adhere to the surface but they are still mobile and attract one another”, explains doctoral candidate Tellkamp. In this way, an artificial epithelium is formed.

The next logical step is to find out if the artificial epithelium works much in the same way as our nasal mucosa. In collaboration with Prof. Olaf Magnussen in the Physics Department of Kiel University atomic force microscopy (AFM) will be used to visualize the light driven, directed transport of nanoscopic particles. The recent findings are particularly interesting, not only with respect to fundamental research. With artificially ciliated epithelia, a molecular nano-fabrication seems possible – machines of molecular size would build other machines by positioning chemical products specifically and precisely. Entire production plants could thus fit onto a tiny chip. Other conceivable fields of application include artificial organelles equipped with molecular cilia that are controlled by an external stimulus; or in the more distant future, they could operate autonomously within the bloodstream and carry drugs to the site of a disease.

Source: Kiel University

Scientists discover the reason that batteries lose capacity over time: Nanocrystals!

In the struggle to develop better batteries, it’s the overall capacity that tends to get most of the attention — we marvel when a new smartphone crams in a few more milliamp-hours. Capacity is nothing without the longevity to survive a large number of repeated charging cycles, though. Even the most advanced lithium-ion batteries still lose capacity as they age, and there’s no way to prevent that until we know the cause, which we might thanks to two new studies from the US Department of Energy. These studies point to tiny nanoscale crystals as the culprits for reduced capacity over time.

The key to unraveling this mystery was to make careful, direct observations of the cathode and anode material used in modern batteries. Scientists had already pinpointed these components as the site of age-related battery erosion, but the specific mechanism was unclear. The team from Brookhaven National Laboratory used a very sensitive transmission electron microscope (TEM) to observe the changes in high-quality nickel-oxide anodes as they were repeatedly charged and discharged.

The experiment showed that as lithium ions pass through cathodes and anodes, they slowly become stuck within the ion channels due to reactions with nickel oxide to produce small crystals (salt buildup, essentially). These crystals alter the structure of the battery and cause other ions to move less efficiently, thus lowering the usable capacity. Surprisingly, the degradation observed by the Brookhaven team didn’t seem to follow any discernible pattern, at least at first.

The ultimate cause of a lithium-ion battery’s imperfections is that, well, its componentsaren’t perfect. The anode and cathode materials, no matter how carefully constructed, have minuscule imperfections that act as a nucleation site for crystal formation. It’s a bit like heating water in a totally smooth container versus one with surface disruptions. The bubbles need some sort of irregularity on which to form, and it’s the same with the nanocrystals in batteries. The team refers to this as the chink in the anode’s armor. If there is a place for the crystals to form, they will.

The second study from the Department of Energy’s National Renewable Energy Laboratory looked at the effects of charge speed and capacity on batteries, but focused more on the cathode. This research showed that the race to make higher density batteries could actually be hurting longevity — the bigger the battery and faster it charges, the fewer cycles you get before the nanocrystallization begins to affect it.

So if we can’t simply prevent these nanocrystals from forming, is there a way to reverse the process or at least slow it? It may be possible to treat battery components with a type of atomic deposition to fill in as many of the tiny gaps and imperfections as possible with nanoparticles. This would at least slow the formation of blockages in the ion channels. Even if that doesn’t solve the problem entirely, it could allow engineers to continue ramping up energy density without sacrificing durability. Careful examination of the structure of these crystals could even lead to ways of breaking them apart to revitalize old batteries.

This research might end up being more vital than efforts to boost the capacity of batteries to power faster hardware — in many cases the lifetime of a product is determined by how many cycles the battery can take. This is becoming even more important as companies increasingly push non-removable batteries in laptops, smartphones, and tablets, yet again reminding us that we truly are slaves of electricity.

Graphene ‘spaser’ brings optical computing to the nano-scale!

New research in an area called plasmonics has raised hopes for all sorts of seemingly implausible inventions, like cancer-killing nanotubes and mobile phones printed into t-shirts. It’s yet another breakthrough we can chalk up to carbon nanotubes and their sister material graphene, which have allowed researchers to replicate the functions of a laser on a much smaller scale than boring old light could ever allow.

One of the biggest problems with using light for industry is that it does not scale. Light of a particular color has a set wavelength, and that wavelength remains static regardless of the size of the generator; the green light of a pocket-sized laser pointer can have the same wavelength as that produced by a building-sized space-laser.

This has the big advantage of providing astronomers with sensible optical information about the rest of the universe, but it also places a hard limit on miniaturization of optical devices. At scales smaller than about half the wavelength of the light being created, it’s impossible to do useful optical work. For reference, visible light runs from about 400 to about 700 nanometers in wavelength, meaning light in that range is dozens of times fatter than the scale of modern transistors.

One proposed solution to this problem is called Surface Plasmon Amplification by Stimulated Emission of Radiation, or a “spaser.” Spasers are generally referred to as nano-scale lasers, though the two technologies seem to have few similarities. Spasers basically trade photons for resonating electrons, sending optical signals called surface plasmons down the a physical substrate (thus, the field is called plasmonics). This differs from electrical conductivity in that when these surface plasmons reach their destination at the other end of the spaser, they behave like photons of light in every way that matters to a computer engineer.

Until now, the only appropriate substrate for a spaser has been bunches of quantum dots or nanoparticles of precious metal. Graphene, however, has the electrical and optical properties needed for a spaser, along with the added bonus of being strong enough for use in the real world. Graphene is an almost theoretically small substance, just a single atom thick in its purest form; this is one of the smallest sorts of computing possible.

This spaser from 2009 uses gold nano particles to create its surface plasmons.

The potential impact of this sort of technology, which is collectively referred to as “nano-photonics,” is enormous. Prior research has shown that carbon nanotubes can be made to grow toward target cells in living tissue — if this nanotube was a hunter-killer spaser, it might be able to blast its target diseased cell to death without disturbing any healthy neighbours. We could weave a nanotube antenna into your clothing, turning you into a walking receiver. It has even been predicted to increase the zoom on optical microscopes by a factor of 10.

This could also be a way around the impending doom of Moore’s Law; so-called optical computing with light instead of electricity is already theorized to allow much higher computing speeds than conventional chips. The former impossibility of doing that kind of work with light on a scale useful for computing, however, has kept the idea from getting the sort of attention it could well deserve.

The gain element for this metaphorical laser is a carbon nanotube element, which was found to very easily pass energy to and from graphene elements. The whole system uses materials that set new records for strength, flexibility, conductivity, and more. Best of all,carbon nanotubes are carbon, life’s primary structural component. This means that graphene spaser-based devices could be biodegradable, too.

This is all a long way off; all that’s been invented here are nano-scale plasmonics made of carbon. It will be up to other researchers to take advantage of all the potential they bring, but there’s already more than enough theory to get started.