Tiny channels carry big information

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They say it's the little things that count, and that certainly holds true for the channels in transmembrane proteins, which are small enough to allow ions or molecules of a certain size to pass through, while keeping out larger objects. Artificial fluidic nanochannels that mimic the capabilities of transmembrane proteins are highly prized for a number of advanced technologies. However, it has been difficult to make individual artificial channels of this size– until now.

Researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory have been able to fabricate nanochannels that are only two nanometers (2-nm) in size, using standard semiconductor manufacturing processes. Already they've used these nanochannels to discover that fluid mechanics for passages this small are significantly different not only from bulk-sized channels, but even from channels that are merely 10 nanometers in size.

"We were able to study ion transport in our 2-nm nanochannels by measuring the time and concentration dependence of the ionic conductance,"says Arun Majumdar, Director of DOE's Advanced Research Projects Agency– Energy (ARPA-E), who led this research while still a scientist at Berkeley Lab."We observed a much higher rate of proton and ionic mobility in our confined hydrated channels– up to a fourfold increase over that in larger nanochannels (10-to-100 nm). This enhanced proton transport could explain the high throughput of protons in transmembrane channels."

Majumdar is the co-author with Chuanhua Duan, a member of Majumdar's research group at the University of California (UC) Berkeley, of a paper on this work, which was published in the journalNature Nanotechnlogy. The paper is titled"Anomalous ion transport in 2-nm hydrophilic nanochannels."

In their paper, Majumdar and Duan describe a technique in which high-precision ion etching is combined with anodic bonding to fabricate channels of a specific size and geometry on a silicon-on-glass die. To prevent the channel from collapsing under the strong electrostatic forces of the anodic bonding process, a thick (500 nm) oxide layer was deposited onto the glass substrate.

"This deposition step and the following bonding step guaranteed successful channel sealing without collapsing,"says Duan."We also had to choose the right temperature, voltage and time period to ensure perfect bonding. I compare the process to cooking a steak, you need to choose the right seasoning as well as the right time and temperature. The deposition of the oxide layer was the right seasoning for us."

The nanometer-sized channels in transmembrane proteins are critical to controlling the flow ofionsandmoleculesacross the external and internal walls of a biological cell, which, in turn, are critical to many of the biological processes that sustain the cell. Like their biological counterparts, fluidic nanochannels could play critical roles in the future of fuel cells and batteries.

"Enhanced ion transport improves the power density and practical energy density of fuel cells and batteries,"Duan says."Although the theoretical energy density in fuel cells and batteries is determined by the active electrochemical materials, the practical energy density is always much lower because of internal energy loss and the usage of inactive components. Enhanced ion transport could reduce internal resistance in fuel cells and batteries, which would reduce the internal energy loss and increase the practical energy density."

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Artificial fluidic nanochannels, like these 30-nm channels shown under fluorescence, mimic the capabilities of transmembrane proteins and are highly prized for advanced technology applications. Credit: Image courtesy of Majumdar group, UC Berkeley

The findings by Duan and Majumdar indicate that ion transport could be significantly enhanced in 2-nm hydrophilic nanostructures because of their geometrical confinements and high surface-charge densities. As an example, Duan cites the separator, the component placed between the between the cathode and the anode in batteries and fuel cells to prevent physical contact of the electrodes while enabling free ionic transport.

"Current separators are mostly microporous layers consisting of either a polymeric membrane or non-woven fabric mat,"Duan says."An inorganic membrane embedded with an array of 2-nm hydrophilic nanochannels could be used to replace current separators and improve practical power and energy density."

The 2-nm nanochannels also hold promise for biological applications because they have the potential to be used to directly control and manipulate physiological solutions. Current nanofluidic devices utilize channels that are 10-to-100 nm in size to separate and manipulate biomolecules. Because of problems with electrostatic interactions, these larger channels can function with artificial solutions but not with natural physiological solutions.

"For physiological solutions with typical ionic concentrations of approximately 100 millimolars, the Debye screening length is 1 nm,"says Duan."Since electrical double layers from two-channel surfaces overlap in our 2-nm nanochannels, all current biological applications found in larger nanochannels can be transferred to 2-nm nanochannels for real physiological media."

The next step for the researchers will be to study the transport of ions and molecules in hydrophilic nanotubes that are even smaller than 2-nm. Ion transport is expected to be even further enhanced by the smaller geometry and stronger hydration force.

"I am developing an inorganic membrane with embedded sub-2 nm hydrophilic nanotube array that will be used to study ion transport in both aqueous and organic electrolytes,' Duan says."It will also be developed as a new type of separator for lithium-ion batteries."

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New method for making tiny catalysts holds promise for air quality

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Fortified with iron: It's not just for breakfast cereal anymore. University of Illinois researchers have demonstrated a simpler method of adding iron to tiny carbon spheres to create catalytic materials that have the potential to remove contaminants from gas or liquid.

Civil and environmental engineering professor Mark Rood, graduate student John Atkinson and their team described their technique in the journalCarbon.

Carbon structures can be a support base for catalysts, such as iron and other metals. Iron is a readily available, low-costcatalystwith possible catalytic applications for fuel cells and environmental applications for adsorbing harmful chemicals, such as arsenic or carbon monoxide. Researchers produce a carbon matrix that has manyporesor tunnels, like a sponge. The large surface area created by the pores provides sites to disperse tiny iron particles throughout the matrix.

A common source of carbon is coal. Typically, scientists modify coal-based materials into highly porous activated carbon and then add a catalyst. The multi-step process takes time and enormous amounts of energy. In addition, materials made with coal are plagued by ash, which can contain traces of other metals that interfere with the reactivity of the carbon-based catalyst.

The Illinois team's ash-free, inexpensive process takes its carbon from sugar rather than coal.

In one continuous process, it produces tiny, micrometer-sized spheres of porous, spongy carbon embedded with ironnanoparticles– all in the span of a few seconds.

"That's what really sets this apart from other techniques. Some people have carbonized and impregnated with iron, but they have no surface area. Other people have surface area but weren't able to load it with iron,"Atkinson said."Our technique provides both the carbon surface and the iron nanoparticles."

The researchers built upon a technique called ultrasonic spray pyrolysis (USP), developed in U. of I. chemistry professor Kenneth Suslick's lab in 2005. Suslick used a household humidifier to make fine mist from a carbon-rich solution, then directed the mist through an extremely hot furnace, which evaporated the water from each droplet and left tiny, highly porous carbon spheres.

Atkinson used USP to make his carbon spheres, but added an iron-containing salt to a carbon-rich sugar solution. When the mist is piped into the furnace, the heat stimulates achemicalreaction between the solution ingredients that creates carbon spheres with iron particles dispersed throughout.

"We were able to take advantage of Dr. Suslick's USP technique, and we are building upon it by simultaneously impregnating the porous carbons with metal nanoparticles,"Atkinson said."It's simple because it's continuous. We can isolate the carbon, add pores, and impregnate iron into the carbon spheres in a single step."

Another advantage of the USP technique is the ability to create materials to address particular needs. By fabricating the material from scratch, rather than trying to modify off-the-shelf products, scientists and engineers can develop materials for specific problem-solving scenarios.

"Right now, you take coal out of the ground and modify it. It's difficult to tailor it to solve a particular air quality problem,"Rood said."We can readily change this new material by how it's activated to tailor its surface area and the amount of impregnated iron. This method is simple, flexible and tailorable."

Next, the researchers will explore applications for the material. Rood and Atkinson have received two grants from the National Science Foundation to develop the carbon-iron spheres to remove nitric oxide, mercury, and dioxin from gas streams– bioaccumulating pollutants that have caused concern as emissions from combustion sources.

Currently, the three pollutants can be dealt with separately by carbon-based adsorbents and catalysts, but the Illinois team and collaborators in Taiwan hope to harness carbon's adsorption properties and iron's reactivity to remove all three pollutants from gas streams simultaneously.

"We're looking at taking advantage of their porosity and, ideally, their catalytic applications as well,"Atkinson said."Carbon is a very versatile material. What's in my mind is a multi-pollutant control where you can use the porosity and the catalyst to tackle two problems at once."

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World's smallest Christmas card produced by UG engineers

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(PhysOrg.com) -- It wouldn't look good on the mantelpiece and is bound to get lost in the post– it’s the world’s smallest Christmas card.

Engineers from the University of Glasgow produced it to highlight their world-leadingnanotechnologyexpertise.

Invisible to the naked eye, the card is so small that 8276 of them could fit on an area the size of a first class stamp.

Using nanotechnology, Professor David Cumming and Dr. Qin Chen from the University’s School of Engineering etched the Christmas tree image onto a minute piece of glass.

Professor Cumming said:“Our nanotechnology is among the best in the world but sometimes explaining to the public what the technology is capable of can be a bit tricky.

“We decided that producing this Christmas card was a simple way to show just how accurate our technology is. The process to manufacture the card only took 30 minutes. It was very straightforward to produce as the process is highly repeatable– the design of the card took far longer than the production of the card itself.

“The card is 200 micro-meters wide by 290 micro-metres tall. To put that into some sort of perspective, a micro-meter is a millionth of a metre; the width of a human hair is about 100 micro-meters. You could fit over half a million of them onto a standard A5 Christmas card– but signing them would prove to be a bit of a challenge.”

The colors were produced by plasmon resonance in a patterned aluminium film made in the University of Glasgow’s James Watt Nanofabrication Center.

Although the Christmas card example is a simple demonstration, the underlying technology has some very important real world applications.

The electronics industry is taking advantage of micro and nano-fabrication technology by using it in bio-technology sensing, optical filtering and light control components. These applications are critical in the future development of the digital economy and the emerging healthcare technology markets. This technology could eventually find its way into cameras, television and computer screens to reduce the manufacturing cost.

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World’s first diamond nanoelectromechanical switch

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Japanese researchers have succeeded in the batch fabrication of suspended structures (cantilevers and bridges) of single crystal diamond for nano/micro electromechanical systems.

Dr. Meiyong Liao, a Senior Researcher of Sensor Materials Center, National Institute for Materials Science, cooperated with his colleagues, succeeded in the batch fabrication of suspended structures (cantilevers and bridges) of single crystal diamond for nano/micro electromechanical systems (NEMS/MEMS). Based on this process, they achieved in the world the first single crystal diamond NEMS switch.

The NEMS switch has the advantages of low-leakage current, low-power consumption and sharp on/off ratio in comparison with the conventional semiconductor devices. Most of the existing NEMS/MEMS switches are based on silicon or metal materials, which have the drawbacks of poor mechanical, chemical, and thermal stability, poor reliability and durability. Diamond is the ideal material for NEMS/MEMS due to the highest elastic modulus, mechanical hardness,thermal conductivity, and variableelectrical conductivityfrom insulator to conductor. However, due to the difficultly in fabricating suspended structures of single crystal diamond, the development of single crystal diamond NEMS/MEMS deviceshas been a challenge.

The NIMS research team developed a process for fabricating suspended single crystal diamond structures by locally forming a graphite sacrificial layer in a singlecrystal diamondsubstrate by high energyion implantation, followed by the growth of a diamond epilayer with electrical conductivity by microwave plasmachemical vapor depositionmethod (MPCVD) and the removal of the graphite sacrificial layer. As a further development of this technique, the group also succeeded for the first time in fabricating NEMS switching devices with a transistor-like structure comprising 3 electrodes.

The leakage current of the developed diamond NEMS switch is very low, and thepower consumptionis less than 10pW (picowatt). The devices exhibit high reproducibility, high reliability and no surface stiction. Stable operation of the diamond NEMS switch in a high temperature environment (250°C) was also confirmed. The Young’s modulus of the moveable cantilever structure was measured to be 1100GPa, which is close to the value of bulk diamond single crystals. Thus, high-speed (gigahertz) switching operation can be expected.

In comparison with the existing MEMS switches, the diamond NEMS switches are expected to show greatly improved functions, including reliability, lifetime, speed, and electrical handling capacity, etc. The developed devices can be applied as microwave switch for next-generation wireless communications and logic circuit under harsh environments. These research results also establish the infrastructure for diamond NEMS/MEMS with novel functions, opening the way for the development of various chemical, physical, and mechanical sensors.

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DNA can act like Velcro for nanoparticles

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DNA can do more than direct how bodies our made -- it can also direct the composition of many kinds of materials, according to a new study from the U.S. Department of Energy’s Argonne National Laboratory.

Argonne researcher Byeongdu Lee and his colleagues at Northwestern University discovered that strands of DNA can act as a kind of nanoscopic"Velcro"that binds differentnanoparticlestogether."It’s generally difficult to precisely control the assembly of these types of nanostructures,"Lee said."By using DNA, we’re borrowing nature's power."

The"Velcro"effect of the DNA is caused by the molecule’s"sticky ends,"which are regions of unpaired nucleotides— the building blocks of DNA— that are apt to bond chemically to their base-pair partners, just like in our genes. When sufficiently similar regions contact each other, chemical bonds form a rigid lattice. Scientists and engineers believe these complex nanostructures have the potential to form the basis of new plastics, electronics and fuels.

In 2008, Lee and his colleagues attached DNA to spherical nanoparticles made of gold, hoping to control the way the particles arrange themselves into compact, ordered crystals. This process is called nanoparticle"packing,"and Lee believed that by affixing DNA to the nanoparticles, he could control how they packed together."Materials that are packed differently— even if they are made from the same substance— have been shown to exhibit dramatically different physical and chemical properties,"Lee said.

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While the 2008 experiment showed that DNA appeared to control that instance of nanosphere packing, it was not known whether the effect would occur with different nanoparticle geometries. The more recent experiment looked at different shapes of nanoparticles to determine whether their contours affected how they packed.

According to Lee, the spherical nanoparticles in the earlier experiment tended to arrange themselves into one of two separate types of cubic crystals: a face-centered cube (a simple cube with nanospheres at each vertex and additional ones located in the middle of each face) or a body-centered cube (a simple cube with an additional nanosphere located in the middle of the cube itself). The type of lattice that the nanoparticles formed was determined by how the"sticky ends"attached to the nanoparticles paired together.

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In the more recent experiment, the particles' shape did change the material's final structure, but only insofar as it altered how the DNA"sticky ends"attached to each other. In fact, the study showed that dodecahedral (12-sided) nanoparticles arranged into a face-centered cubic configuration while octahedral (8-sided) nanoparticles formed body-centered cubes— even when the nanoparticles were attached to identical strands of DNA."We may be able to make all different types of nanoparticle packing structures, but the structure that will result will always be the one that maximizes the amount of binding,"he said.

"The face-centered cubic structure is the most compact way for the nanoparticles to arrange themselves, while the body-centered cubic is slightly less compact. TheDNAbinding is really the true force controlling the construction of the lattice,"he added.

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Doctoral candidate publishes on graphene's potential

Since graphene was first isolated in 2004 with the help of Scotch tape, researchers have excitedly turned to the material to discover its potential applications. A single layer of carbon atoms whose applications range from ultrafast electronics to biosensors to flexible displays, graphene is strong, light, transparent, and a conductor of heat and electricity. But what can we do with this new material? As researchers across the globe peel away layer after layer of potential application, Milan Begliarbekov, a doctoral candidate at Stevens Institute of Technology, has found some unique applications for this distinctive material.

Graphene is charged with possibilities for Milan. With the help of a world-class Stevens faculty, support from the National Science Foundation (NSF) Graduate Teaching Fellows in K-12 Education (GK-12) program through the New Jersey Alliance for Engineering Education (NJAEE), and an award from the Air Force Office of Scientific Research (AFOSR), Milan is conducting groundbreaking research of the material. He has already published two papers ongrapheneinApplied Physics Lettersin pursuit of his Ph.D. and has a third paper in the pipeline. Both published articles have also been selected for theVirtual Journal of Nanoscale Science and Technology.

His first published article,"Determination of edge purity in bilayer graphene usingµ-Raman spectroscopy,"confirms a technique for differentiating between monolayer and bilayer graphene, and introduces a new method to quantify the composition of graphenes chiral edges throughµ-Raman spectroscopy.

Milan's second article,"Aperiodic conductivity oscillations in quasiballistic graphene heterojunctions,"establishes a new signature of Klein tunneling in graphene heterojunctions. The research has applications in nanolectronics such as graphene field effect transistors (GFET), which have been shown to be capable of ultra-high frequency (300 GHz) operation.

Milan's next article, yet to be published, is"Quantum Inductance and High Frequency Oscillators in Graphene Nanoribbons."The paper proposes a novel technique for measuring the speed of ultra-high frequency transistors. Currently it is very difficult to measure ultra-high-frequency signals above 40 GHz by purely electronic means. However, Milan's research indicates that graphene nanoribbons can serve as all-electronic ultra-high frequency oscillators and filters, which would extend the possibilities of high-frequency electronics into new realms.

Since graphene planes were first isolated, much research has focused on the material's applications in nanoelectronics, due to its high electrical conductivity. But researchers at Stevens have taken a different approach, pioneering applications of this unique material in optics. Milan's research represents a fine example of this innovative thinking.

As he works with a material whose greatest applications may still be unrealized, Milan says he enjoys the level of creativity he is afforded in exploring graphene's possibilities."I like working with Professor Strauf, because of the freedom he gives me to choose my own research projects,"Milan says."He allows me to explore things I find interesting, rather than asking me to work on a pre-defined research objective."

"Given that the our team just started two years ago to work with graphene in a collaboration with Professor Yang's group from the Mechanical Engineering Department, Milan's research success is quite remarkable,"says Dr. Stefan Strauf, Assistant Professor of Physics and Engineering Physics (PEP) and Director of the Nanophotonics lab."Milan is one of these unique graduate students you would like to clone into a dozen in your lab in order to implement all of his ideas."

The exploration of ideas has also led to the creation of a system that utilizes graphene's unique reaction to light. Working with Stevens faculty Dr. Stefan Strauf and Dr. Chris Search, who is also an Assistant Professor of PEP, Milan is determined to convert new ideas into patentable technology."We are pleased to announce that with the help of the Office of Academic Entrepreneurship, Milan is in the process of applying for a patent with a novel application of graphene that exploits its near-perfect efficiency as aconductor,"says Dr. Christos Christodoulatos, Professor and Associate Provost of Academic Entrepreneurship.

In addition to the AFOSR grant, Milan was also supported by the NSF GK-12 program through NJAEE. As an NJAEE fellow from 2008 to 2010, Milan worked alongside teacher mentors in local high school classrooms to expose younger students to cutting edge science and engineering research. The GK-12 program was established to support the NSF's goal of enhancing science, technology, engineering, and mathematics (STEM) curriculums for K-12 teachers and students."The NJAEE program provides a unique opportunity for graduate students to enhance their teaching and communication skills, instills in them the spirit of innovation and entrepreneurship, and at the same time provides them a forum to share their passion and enthusiasm for science and engineering with younger students,"says Dr. Frank Fisher, Associate Professor of Mechanical Engineering and co-Director of the Stevens Nanotechnology Graduate Program who is a co-PI on the NJAEE project."Milan was just fantastic as a NJAEE Fellow, and has recently been able to apply these skills as an instructor in the Physics department here at Stevens as well as Queensborough Community College of CUNY."

The patent and papers are the most recent examples of Milan's success at Stevens. As an undergraduate at Stevens, Begliarbekov took advantage of both the Charles V. Schaeffer, Jr. School of Engineering and Sciences and what would become the College of Arts and Letters to graduate with two degrees, a B.S. in Physics and a B.A. in Literature. Having taken graduate-level courses in nanotechnology as an undergraduate,"I was already ahead of the curve,"he says, when it came to searching for a graduate program.

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Secrets of nanohair adhesion un-peeled by UA polymer scientists

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Not long after Dr. Ali Dhinojwala, chairman of The University of Akron Department of Polymer Science, unpeeled the secret (fine, clingy hairs) behind the remarkable adhesion of gecko feet, he and fellow researchers came up with a synthetic replica: carbon nanotubes. Now, five years after that initial discovery, the basis of the success of these nanotubes is published in the Oct. 12, 2010, issue of the American Chemical Society’s<i><a href="http://pubs.acs.org/doi/pdf/10.1021/nl102398w">Nano Letters</a></i>.

While the story of nanotubes is one of success, not all carbon nanotubes are equal, nor is the individual adhesion performance of each strand, according to Dhinojwala. Although Dhinojwala and UApolymerscience graduate student Liehui Ge determined that these 8-nanometer-diameter carbon hairs— each 2,000 times smaller than the diameter of a human hair— adhere powerfully to glass and similar substrates, they furthered their research to learn why some strands have a firmer grip than others.

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Getting a grip on adhesion

Findings by the UA scientists, in collaboration with Lijie Ci and Anubha Goyal, researchers with the Department of Mechanical Engineering and Materials Science at Rice University; Rachel Shi, UA Research Experience for Undergraduates (REU) intern; and L. Mahadevan, professor of applied mathematics and professor of organismic and evolutionary biology at Harvard University, reveal that the softer the nanotube, the greater its adhesion.

Using a combination of mechanics, electrical resistance and scanning electron microscopy (SEM) to study the contact between hairs of a large number of vertically aligned carbon nanotubes with glass or silicon substrates, the researchers found that soft nanotubes clasp and curve when pressure is applied, contributing to their adhesive strength.

“We found out that the diameter of the tubes is an important parameter for adhesion because we have to balance the adhesion and bending rigidity of the tubes,” Ge says.“Also, if you apply a high pressure, the tubes bend and buckle and make a larger contact area with the surface, which is the reason for higheradhesion.”

The dry adhesive, unlike liquid glue counterparts, promises successful use in extreme atmospheric and temperature conditions and in other applications that present challenges.

“The carbon nanotube-based gecko adhesives are going to open up opportunities to using these materials on robots, to climb vertical walls, and could actually be used in outer space (vacuum condition) because these materials stick without any liquid glue,” Dhinojwala says.

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NASA engineers develop 'blacker than black' nanotubes (w/ Video)

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(PhysOrg.com) -- Black is black, right? Not so, according to a team of NASA engineers now developing a blacker-than pitch material that will help scientists gather hard-to-obtain scientific measurements or observe currently unseen astronomical objects, like Earth-sized planets in orbit around other stars.

The nanotech-based material now being developed by a team of 10 technologists at the NASA Goddard Space Flight Center in Greenbelt, Md., is a thin coating of multi-walled carbon nanotubes— tiny hollow tubes made of pure carbon about 10,000 times thinner than a strand of human hair. Nanotubes have a multitude of potential uses, particularly in electronics and advanced materials due to their unique electrical properties and extraordinary strength. But in this application, NASA is interested in using the technology to help suppress errant light that has a funny way of ricocheting off instrument components and contaminating measurements.

Better than Paint

"This is a technology that offers a lot of payback,"said engineer Leroy Sparr, who is assessing its effectiveness on the Ocean Radiometer for Carbon Assessment (ORCA), a next-generation instrument that is designed to measure marine photosynthesis."It's about 10 times better than black paint"typically used by NASA instrument designers to suppress stray light, he said.

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Multi-walled carbon nanotubes are tiny hollow tubes made of pure carbon about 10,000 times thinner than a strand of human hair. NASA is investigating their use to help suppress errant light that ricochets off instrument components and contaminates measurements. Credit: NASA

The technology works because of its super-absorption abilities. The nanotubes themselves are packed vertically much like a shag rug. The tiny gaps between the tubes absorb 99.5 percent of the light that hits them. In other words, very few photons are reflected off thecarbon-nanotubecoating, which means that stray light cannot reflect off surfaces and interfere with the light that scientists actually want to measure. The human eye sees the material as black because only a small fraction of light reflects off the material.

The team began working on the technology in 2007. Unbeknownst to the group, the New York-based Rensselaer Polytechnic Institute also had initiated a similar effort and announced in 2008 that its researchers had developed the darkest carbon nanotube-based material ever made— more than three times darker than the previous record.

"Our material isn't quite as dark as theirs,"said John Hagopian, the principal investigator leading the development team."But what we're developing is 10 times blacker than current NASA paints that suppress system stray light. Furthermore, it will be robust for space applications,"he said.

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NASA's Goddard Space Flight Center has a team of scientists testing micro and nanotechnology to use on spacecraft. The goal is to reduce the reflection off the surface of instruments satellites so that the data does not get polluted by the scattered light. The carbon nanotubes that the team grows have proven to be 10 times better than the NASA Z306 paint, currently used on spacecraft instruments.

That is an important distinction, said Carl Stahle, assistant chief of technology for Goddard's Instrument Systems and Technology Division. Not all technology can be used in space because of the harsh environmental conditions encountered there."That's the real strength of this effort,"Stahle said."The group is finding ways to apply new technology and fly it on our instruments."

Big Breakthrough

The breakthrough was the discovery of a highly adhesive underlayer material upon which to grow the carbon nanotubes, which are just a few tens of nanometers in diameter. To grow carbon nanotubes, materials scientists typically apply a catalyst layer of iron to an underlayer on the silicon substrate. They then heat the material in an oven to about 750° C (1,382° F). While heating, the material is bathed in carbon-containing feedstock gas.

Stephanie Getty, the materials scientist on Hagopian's team, varied the underlayer as well as the thickness of the catalyst materials to create carbon nanotubes that not only absorb light, but also remain fixed to the material upon which they are grown. As a result, they are more durable and less likely to scratch off. The team also has grown durable nanotube coatings on titanium, a better structural material for space use. The team now is fine-tuning production techniques to assure consistent quality and light-suppression capabilities, Hagopian said.

New Capabilities Added

Should the team prove the material's suitability in space, the material would provide real benefits to instrument developers, Hagopian added.

Currently, instrument developers apply black paint to baffles and other components to reduce stray light. Because reflectance tests have shown the coating to be more effective than paint, instrument developers could grow the carbon nanotubes on the components themselves, thereby simplifying instrument designs because fewer baffles would be required. To accommodate larger components, the team now is installing a six-inch furnace to grow nanotubes on components measuring up to five inches in diameter. And under a NASA R&D award, the team also is developing a separate technique to create sheets of nanotubes that could be applied to larger, non-conforming surfaces.

In addition to simplifying instrument design, the technology would allow scientists to gather hard-to-obtain measurements because of limitations in existing light-suppression techniques or to gather information about objects in high-contrast areas, including planets in orbit around other stars, Hagopian said.

The ORCA team, which is fabricating and aligning an instrument prototype, is the first to actually apply and test the technology. The instrument is the front-runner for the proposed Aerosol/Cloud/Ecosystems (ACE) mission and requires robust light-suppression technologies because more than 90 percent of the light gathered by the instrument comes from the atmosphere. Therefore, the team is looking for a technique to suppress the light so that it doesn't contaminate the faint signal the team needs to retrieve.

"It's been an issue with all the (ocean sensors) we've flown so far,"said ORCA Principal Investigator Chuck McClain.

Working with the ORCA team, Hagopian's group grew the coating on a slit, the conduit through which all light will pass on ORCA."Having an efficient absorber is critical and the nanotubes could provide the solution,"McClain said."Right now, it looks promising,"Sparr added."If I can support them and they can continue advancing the technology so that it can be applied to other spacecraft components, it could be a very important development for NASA."

Goddard Chief Technologist Peter Hughes agrees, and, in fact, selected Hagopian and his team to receive his organization’s 2010"Innovator of the Year"award."Our job is to develop and advance new technology that will ultimately result in better scientific measurements. Goddard has a well-deserved reputation for creating technologies that enhance instrument performance because we are adept at quickly infusing emerging technology for specific spaceflight applications. John’s team demonstrated that key strength. And in doing so, he’s leading the way in NASA’s quest to bring about a new level of scientific discovery,"Hughes said.

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What changes will nanoelectronics bring to our lives?

We are surrounded by nanoelectronics through products such as computers, mobile phones, sensors and electric cars. Nanoelectronics may also grow much stronger in the energy efficiency area in the near future. However, the sustainable growth faces several challenges.

Innanoelectronics, miniaturisedelectronic circuitsare integrated on semiconductor chips where the basic element is the transistor. The size of the transistors produced is under 100 nm. Andreas Wild is Executive Director of the ENIAC JU. The task of this public-private partnership is to coordinate European research in nanoelectronics. He sees many interesting changes coming with the evolution of nanoelectronics.

“We have little electronics in the buildings, but the buildings are huge energy consumers. There will be an influx of nanoelectronics that will completely change the ways we are living in and using buildings, making them energy self-consistent, extremely comfortable and adaptable to the needs of the people. The buildings will be able to read how many people are inside, what are they doing, then adjust everything and also give the people a human interface to express their wishes. Rather than pilot projects this will be the norm. Europe has already issued regulations. I believe in the next five to ten years nobody will construct a building that haven’t got these features.”

Laurent Malier, CEO of the research center CEA-Leti in France, highlights another area where nanoelectronics may be prominent.“What we are going to explore more are nanoelectronic devices for biology and healthcare. It could be easy and low cost diagnostics. This is an area of growth in a large perspective,” he said.

The sustainable growth of nanoelectronics faces several challenges.“You see technological challenges, materials, processes and so forth. You see design challenges, how to put together billions of components quickly, reliably and predictably. Then there are systemic challenges, what are the functions that all these billions oftransistorsare supposed to achieve on every chip and how do they relate to the everyday life of the people using the devices,” Wild said.

Malier sees additional challenges.“One is the compromise between low electrical power consumption and very fast processing capability. The other one is lithography, the capability to reduce the size of features. The third one is to increase complexity with either 3D integration, stacking chips on each other, or integration of new functions.”
We are dependent on nanoelectronic devices and soon we might see a drastic reduction in our energy consumption thanks to the advances in this area.

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Scientists imitate nature to engineer nanofilms

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In nature, water striders can walk on water, butterflies can shed water from their wings, and plants can trap insects and pollen. Scientists at the Naval Research Laboratory are part of a research team working to engineer surfaces that imitate some of these water repellency features found in nature.

This technology offers the possibility of significant advances for producing new generations of coatings that will be of great value for military, medical, and energy applications. The research is published in the December 2010 issue ofNature Materials.

Dr. Walter Dressick from NRL, working with Professor Melik Demirel of Penn State and Dr. Matthew Hancock of MIT, have collaborated to create an engineered water-repellant thin film. What sets this development apart from earlier technologies is that this newest film has the ability to control the directionality of liquid transport.

In this system, parylene nanorods are deposited on the surface by a simple, straightforwardvapor depositionmethod. The single step usually takes less than 60 minutes, compared with the more complex, multi-step lithography processes often used in previous systems. This is the first time this kind of surface has been engineered at the nanoscale.

In the newly created surface, the nanorods that form the film are smooth on a micron scale. This size and smoothness in the posts means that when droplets are placed on the surface, they move without being distorted in any way. Also, they can be moved without pumps or optical waves. Previous systems caused thewater dropletsto be distorted, which could rupture, spill, or destroy the cargo in the droplet when used in medical or microassembly applications. As they continue the research, the team will focus on optimizing the droplet transport mechanism and tuning the preparation method.

Looking to the future, researchers are hopeful that this film could be used as a coating on the hull of ships where it would reduce the drag and slow the fouling. In industry applications, the film might have uses in directional syringes and fluid diodes, pump-free digital fluidic devices, increased efficiency of thermal cooling for microchips, and tire coatings.

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Graphene: Scientists figure out how to shatter the world's strongest material

In 2008, experiments at The Fu Foundation School of Engineering and Applied Science at Columbia University established pure graphene, a single layer of graphite only one atom thick, as the strongest material known to mankind. This raised a question for Chris Marianetti, Assistant Professor in Columbia Engineering's Department of Applied Physics and Applied Mathematics: how and why does graphene break?

Usingquantum theoryand supercomputers, Marianetti has revealed the mechanisms of mechanical failure of pure graphene under tensile stress. In a paper recently accepted for publication in the journalPhysical Review Letters, he shows that, when graphene is subject to strain equal in all directions, it morphs into a new structure which is mechanically unstable.

Marianetti says this failure mechanism is a novel soft-mode phonon instability. A phonon is a collective vibrational mode of atoms within a crystal, similar to a wave in a liquid. The fact that a phonon becomes"soft"under tensile strain means that the system can lower its energy by distorting the atoms along the vibrational mode and transitioning to a new crystalline arrangement. Under sufficient strain, graphene develops a particular soft-mode that causes the honeycomb arrangement ofcarbon atomsto be driven towards isolated hexagonal rings. This new crystal is structurally weaker, resulting in the mechanical failure of the graphene sheet.

"This is exciting on many different levels,"Marianetti notes."Soft modes were first recognized in the 1960s in the context of ferroelectric phase transitions, but they have never been directly linked to fracture. Typically, defects in a material will always cause failure to happen prematurely, but the pristine nature of graphene allows one to test our prediction. We have already outlined some interesting new experiments to directly observe ourtheoretical predictionof the soft mode."

Marianetti added that this is the first time a soft optical phonon has ever been linked to mechanical failure and that therefore it is likely that this novel failure mechanism is not exclusive to graphene but may be prevalent in other very thin materials."With nanotechnology becoming increasingly ubiquitous, understanding the nature of mechanical behavior in low dimensional systems such as graphene is of great importance. We think strain may be a means to engineer the properties ofgraphene, and therefore understanding its limits is critical."The research was funded by the National Science Foundation.

Marianetti's research interests lie in the use of classical and quantum mechanics to model the behavior of materials at the atomic scale. In particular, he is focused on applying these techniques to materials with potential for energy storage and conversion. Current applications in his research program range from nuclear materials such as plutonium to rechargeable battery materials such as cobalt oxides.

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