UT Tyler Announces IEEE Nanotechnology Student Branch Chapter
The University of Texas at Tyler has created a student chapter of the Institute of Electrical and Electronics Engineers, Dr. Harold Doty, College of Business and Technology dean, announced. The UT Tyler IEEE Nanotechnology Student Branch Chapter is the first of its kind in Texas and only the second one worldwide. "I wanted to create an interest in nanotechnology for students in the industrial technology program. The chapter is a perfect platform to get students involved,” said Dr. Dominick Fazarro, UT Tyler associate professor and chapter adviser. “Nanotechnology is considered the new industrial revolution, and students need to know the future implications and impact in society.” Nanotechnology is the engineering science of creating materials at the atomic and molecular level. It has many applications in a variety of industries including medicine, energy, electronics and computers. One of the 15 campuses of the UT System, UT Tyler offers excellence in teaching, research, artistic performance and community service. More than 80 undergraduate and graduate degree programs are available at UT Tyler, which has an enrollment of almost 7,000 high-ability students at its campuses in Tyler, Longview and Palestine.
Rice University Lab Develops Starfruit-Shaped Nanorods
Gold nanoparticles created by the Rice University lab of Eugene Zubarev take on the shape of starfruit in a chemical bath with silver nitrate, ascorbic acid and gold chloride. Photo courtesy Zubarev Lab/Rice University
They look like fruit, and indeed the nanoscale stars of new research at Rice University have tasty implications for medical imaging and chemical sensing. Starfruit-shaped gold nanorods synthesized by chemist Eugene Zubarev and Leonid Vigderman, a graduate student in his lab at Rice’s BioScience Research Collaborative, could nourish applications that rely on surface-enhanced Raman spectroscopy (SERS). The researchers found their particles returned signals 25 times stronger than similar nanorods with smooth surfaces. That may ultimately make it possible to detect very small amounts of such organic molecules as DNA and biomarkers, found in bodily fluids, for particular diseases. “There’s a great deal of interest in sensing applications,” said Zubarev, an associate professor of chemistry. “SERS takes advantage of the ability of gold to enhance electromagnetic fields locally. Fields will concentrate at specific defects, like the sharp edges of our nanostarfruits, and that could help detect the presence of organic molecules at very low concentration.” SERS can detect organic molecules by themselves, but the presence of a gold surface greatly enhances the effect, Zubarev said. “If we take the spectrum of organic molecules in solution and compare it to when they are adsorbed on a gold particle, the difference can be millions of times,” he said. The potential to further boost that stronger signal by a factor of 25 is significant, he said. Zubarev and Vigderman grew batches of the star-shaped rods in a chemical bath. They started with seed particles of highly purified gold nanorods with pentagonal cross-sections developed by Zubarev’s lab in 2008 and added them to a mixture of silver nitrate, ascorbic acid and gold chloride.
Stanford Engineers Create Piezoelectric Graphene
This illustration shows lithium atoms (red) adhered to a graphene lattice that will produce electricity when bent, squeezed or twisted. Conversely, the graphene will deform when an electric field is applied, opening new possibilities in nanotechnology. (Image Credit: Mitchell Ong / Stanford School of Engineering)
To the long list of exceptional physical properties of graphene, engineers at Stanford University have added yet another: piezoelectricity, the property of some materials to produce an electric charge when bent, squeezed or twisted. In what became known as the "Scotch tape technique," researchers first extracted graphene with a piece of adhesive in 2004. Graphene is a single layer of carbon atoms arranged in a honeycomb, hexagonal pattern. Under a microscope, it looks like chicken wire. In 2010, the researchers who first isolated it shared the Nobel Prize. Graphene is a wonder material. It is a hundred times better at conducting electricity than silicon. It is stronger than diamond. And, at just one atom thick, it is so thin as to be essentially a two-dimensional material. Such promising physics have made graphene the most studied substance of the last decade, particularly in nanotechnology. Yet, while graphene is many things, it is not piezoelectric. Perhaps most valuably, piezoelectricity is reversible. When an electric field is applied, piezoelectric materials change shape, yielding a remarkable level of engineering control. Piezoelectrics have found application in countless devices from watches, radios and ultrasound to the push-button starters on propane grills, but these uses all require relatively large, three-dimensional quantities of piezoelectric materials. The Stanford team's engineered graphene has, for the first time, extended such fine physical control to the nanoscale. "The physical deformations we can create are directly proportional to the electrical field applied and this represents a fundamentally new way to control electronics at the nanoscale," said Evan Reed, head of the Materials Computation and Theory Group at Stanford. "This phenomenon brings new dimension to the concept of 'straintronics' for the way the electrical field strains — or deforms — the lattice of carbon, causing it to change shape in predictable ways." "Piezoelectric graphene could provide an unparalleled degree of electrical, optical or mechanical control for applications ranging from touchscreens to nanoscale transistors," said Mitchell Ong, a post-doctoral scholar in Reed's lab. Using a sophisticated modeling application running on high-performance supercomputers, the engineers simulated the deposition of atoms on one side of a graphene lattice – a process known as doping – and measured the piezoelectric effect. They modeled graphene doped with lithium, hydrogen, potassium and fluorine, as well as combinations of hydrogen and fluorine and lithium and fluorine, on either side of the lattice. Doping just one side of the graphene, or doping both sides with different atoms, is key to the process as it breaks graphene's perfect physical symmetry, which otherwise cancels the piezoelectric effect. The results surprised both engineers. "We thought the piezoelectric effect would be present, but relatively small. Yet, we were able to achieve piezoelectric levels comparable to traditional three-dimensional materials," said Reed. "It was pretty significant."
New Nanoglue is Thin and Supersticky
In this graphic, clockwise from top: the glue can be printed in a pattern on a surface, treated to make it sticky (red) and then a new layer stuck on top. The background is a patterned nanoglue on a surface.
(Tingrui Pan/UC Davis photo)
Engineers at the University of California, Davis, have invented a superthin “nanoglue” that could be used in new-generation microchip fabrication. “The material itself (say, semiconductor wafers) would break before the glue peels off,” said Tingrui Pan, professor of biomedical engineering. He and his fellow researchers have filed a provisional patent. Conventional glues form a thick layer between two surfaces. Pan’s nanoglue, which conducts heat and can be printed, or applied, in patterns, forms a layer the thickness of only a few molecules. The nanoglue is based on a transparent, flexible material called polydimethylsiloxane, or PDMS, which, when peeled off a smooth surface usually leaves behind an ultrathin, sticky residue that researchers had mostly regarded as a nuisance. Pan and his colleagues realized that this residue could instead be used as glue, and enhanced its bonding properties by treating the residue surface with oxygen. The nanoglue could be used to stick silicon wafers into a stack to make new types of multilayered computer chips. Pan said he thinks it could also be used for home applications — for example, as double-sided tape or for sticking objects to tiles. The glue only works on smooth surfaces and can be removed with heat treatment.
Stanford Engineers Weld Nanowires With Light
A bright burst of light has welded these nanowires together.
(Photo: Stanford School of Engineering)
The ability to weld nano-sized wires with just a blast of light could lead to advances in electronics and solar applications. One area of intensive research at the nanoscale is the creation of electrically conductive meshes made of metal nanowires. Promising exceptional electrical throughput, low cost, and easy processing, engineers foresee a day when such meshes are common in new generations of touch screens, video displays, light-emitting diodes, and thin-film solar cells. Standing in the way, however, is a major engineering hurdle: In processing, these delicate meshes must be heated or pressed to unite the crisscross pattern of nanowires that form the mesh, and are thereby damaged. However, engineers at Stanford University have demonstrated a promising nanowire welding technique that harnesses plasmonics to fuse wires with a simple blast of light. At the heart of the technique is the physics of plasmonics, the interaction of light and metal in which the light flows across the surface of the metal in waves, like water on the beach. “When two nanowires lay criss-crossed, we know that light will generate plasmon waves at the place where the two nanowires meet, creating a hot spot. The beauty is that the hot spots exist only when the nanowires touch, not after they have fused. The welding stops itself. It’s self-limiting,” explains senior Mark Brongersma, associate professor of materials science and engineering at Stanford and an expert in plasmonics. “The rest of the wires and, just as importantly, the underlying material are unaffected,” notes Michael McGehee, also an associate professor of materials science and engineering. “This ability to heat with precision greatly increases the control, speed, and energy efficiency of nanoscale welding.”
Pitt Researchers Coax Gold Into Nanowires
Synthesis and characterization of gold nanowires. TEM images showing the assembly of AuNPs on the SWNTs (after 30 min, left) and their welding into AuNWs (after 120 min, right).
(Image Source: University of Pittsburgh)
Researchers at the University of Pittsburgh have coaxed gold into nanowires as a way of creating an inexpensive material for detecting poisonous gases found in natural gas. Along with colleagues at the National Energy Technology Laboratory (NETL), Alexander Star, associate professor of chemistry in Pitt's Kenneth P. Dietrich School of Arts and Sciences and principal investigator of the research project, developed a self-assembly method that uses scaffolds (a structure used to hold up or support another material) to grow gold nanowires. “The most common methods to sense gases require bulky and expensive equipment,” says Star. “Chip-based sensors that rely on nanomaterials for detection would be less expensive and more portable as workers could wear them to monitor poisonous gases, such as hydrogen sulfide.” Star and his research team determined gold nanomaterials would be ideal for detecting hydrogen sulfide owing to gold’s high affinity for sulfur and unique physical properties of nanomaterials. They experimented with carbon nanotubes and graphene—an atomic-scale chicken wire made of carbon atoms—and used computer modeling, X-ray diffraction, and transmission electron microscopy to study the self-assembly process. They also tested the resulting materials’ responses to hydrogen sulfide. “To produce the gold nanowires, we suspended nanotubes in water with gold-containing chloroauric acid,” says Star. “As we stirred and heated the mixture, the gold reduced and formed nanoparticles on the outer walls of the tubes. The result was a highly conductive jumble of gold nanowires and carbon nanotubes.” To test the nanowires’ ability to detect hydrogen sulfide, Star and his colleagues cast a film of the composite material onto a chip patterned with gold electrodes. The team could detect gas at levels as low as 5ppb (parts per billion)—a detection level comparable to that of existing sensing techniques. Additionally, they could detect the hydrogen sulfide in complex mixtures of gases simulating natural gas.
Teen Wins Siemens Competition with Nanotechnology Related Research
Angela Zang.
(Image Source: Siemens Foundation)
2011's highest science honor for high school students was awarded recently to biochemistry research on cancer stem cells the 2011 Siemens Competition in Math, Science & Technology, America’s premier science research competition for high school students. Administered by the College Board, the Siemens Competition is a signature program of the Siemens Foundation, which supports science, technology, engineering and mathematics (STEM) education. Angela Zhang, a senior at Monta Vista High School in Cupertino, CA, won the $100,000 Grand Prize in the individual category for using nanotechnology to eradicate cancer stem cells. In her project, "Design of Image-guided, Photo-thermal Controlled Drug Releasing Multifunctional Nanosystem for the Treatment of Cancer Stem Cells," Angela aimed to design a targeted gold and iron oxide-based nanoparticle with the potential to eradicate cancer stem cells through a controlled delivery of the drug salinomycin to the site of the tumor. The multifunctional nanoparticle combines therapy and imaging into a single platform, with the gold and iron-oxide components allowing for both MRI and Photoacoustic imaging. Angela also won the Intel International Science & Engineering Fair (ISEF) Grand Award for medicine and health science in 2011 and 2010. She spent an estimated 1,000 hours on her research. “Angela created a nanoparticle that is like a Swiss army knife of cancer treatment,” said competition judge Dr. Tejal Desai, professor, Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco. “She showed great creativity and initiative in designing a nanoparticle system that can be triggered to release drugs at the site of the tumor while also allowing for non-invasive imaging. Her work is an important step in developing new approaches to the therapeutic targeting of tumors via nanotechnology.”
Graphene Rips Follow Rules
Research from Rice University and the University of California at Berkeley may give science and industry a new way to manipulate graphene, the new material expected to play a role in advanced electronic, mechanical and thermal applications. When graphene – a one-atom thick sheet of carbon – rips under stress, it does so in a unique way that puzzled scientists who first observed the phenomenon. Instead of tearing randomly like a piece of paper would, it seeks the path of least resistance and creates new edges that give the material desirable qualities. Because graphene's edges determine its electrical properties, finding a way to control them will be significant, said Boris Yakobson, Rice's Karl F. Hasselmann Professor of Mechanical Engineering and Materials Science and professor of chemistry. Yakobson and Vasilii Artyukhov, a postdoctoral researcher at Rice, recreated in computer simulations the kind of ripping observed through an electron microscope by researchers at Berkeley. The California team noticed that cracks in flakes of graphene followed armchair or zigzag configurations, terms that refer to the shape of the edges created. It seemed that molecular forces were dictating how graphene handles stress. Those forces are robust. Carbon-carbon bonds are the strongest known to man. But the importance of this research, Yakobson said, lies in the nature of the edge that results from the rip. The edge of a sheet of graphene gives it particular qualities, especially in the way it handles electric current. Graphene is so conductive that current flows straight through without impediment – until it reaches the edge. What the current finds there makes a big difference, he said, in whether it stops in its tracks or flows to an electrode or another sheet of graphene.
Inventing Self-repairing Batteries
Imagine dropping your phone on the hard concrete sidewalk—but when you pick it up, you find its battery has already healed itself. A team of researchers from the University of Illinois at Urbana-Champaign (UIUC) and the U.S. Department of Energy's (DOE) Argonne National Laboratory are exploring ways to design batteries that heal themselves when damaged. "This would help electronics survive daily use—both the long-term damage caused by charging over and over again, and also the inevitable physical damage of everyday life," said Jeff Moore, a UIUC scientist on the team. Scientists think that loss of electrical conductivity is what causes a battery to fade and die. Theories abound on the specific molecular failures; perhaps chemicals build up on electrodes, or the electrodes themselves pull away. Perhaps it's simply the inevitable stress fractures in materials forced to expand and contract repeatedly as the battery is charged and used. In any case, the battery's storage capacity drops due to loss of electrical conductivity. This is what the team wants to address. The idea is to station a team of "emergency repairmen" already contained in the battery. These are tiny microspheres, each smaller than a single red blood cell, and containing liquid metal inside. Added along with the battery components, they lie dormant for most of the battery's lifetime. But if the battery is damaged, the capsules burst open and release their liquid metal into the battery. The metal fills in the gaps in the electrical circuit, connecting the broken lines, and power is restored.
Rice Chemists Cram 2 Million Nanorods into Single Cancer Cell
Rice University chemists have found a way to load more than 2 million tiny gold particles, called nanorods, into a single cancer cell. The breakthrough could speed development of cancer treatments that would use nanorods like tiny heating elements to cook tumors from the inside. "The breast cancer cells that we studied were so laden with gold nanorods that their masses increased by an average of about 13 percent," said study leader Eugene Zubarev, associate professor of chemistry at Rice. "Remarkably, the cells continued to function normally, even with all of this gold inside them." Though the ultimate goal is to kill cancer, Zubarev said the strategy is to deliver nontoxic particles that become deadly only when they are activated by a laser. The nanorods, which are about the size of a small virus, can harvest and convert otherwise harmless light into heat. But because each nanorod radiates miniscule heat, many are needed to kill a cell. Unfortunately, scientists who study gold nanorods have found it difficult to load large numbers of particles into living cells. For starters, nanorods are pure gold, which means they won't dissolve in solution unless they are combined with some kind of polymer or surfactant. The most commonly used of these is cetyltrimethylammonium bromide, or CTAB, a soapy chemical often used in hair conditioner. CTAB is a key ingredient in the production of nanorods, so scientists have often relied upon it to make nanorods soluble in water. CTAB does this job by coating the surface of the nanorods in much the same way that soap envelopes and dissolves droplets of grease in dishwater. CTAB-encased nanorods also have a positive charge on their surfaces, which encourages cells to ingest them. Unfortunately, CTAB is also toxic, which makes it problematic for biomedical applications. In the new research, Zubarev, Rice graduate student Leonid Vigderman and former graduate student Pramit Manna, now at Applied Materials Inc., describe a method to completely replace CTAB with a closely related molecule called MTAB that has two additional atoms attached at one end. The additional atoms -- one sulfur and one hydrogen -- allow MTAB to form a permanent chemical bond with gold nanorods. In contrast, CTAB binds more weakly to nanorods and has a tendency to leak into surrounding media from time to time, which is believed to be the underlying cause of CTAB-encased nanorod toxicity. It took Zubarev, Vigderman and Manna several years to identify the optimal strategy to synthesize MTAB and substitute it for CTAB on the surface of the nanorods. In addition, they developed a purification process that can completely remove all traces of CTAB from a solution of nanorods.
New Switch Can Improve Electronics
(Image Credit: University of Pittsburgh )
Researchers at the University of Pittsburgh have invented a new type of electronic switch that performs electronic logic functions within a single molecule. The incorporation of such single-molecule elements could enable smaller, faster, and more energy-efficient electronics. “This new switch is superior to existing single-molecule concepts,” said Hrvoje Petek, principal investigator and professor of physics and chemistry in the Kenneth P. Dietrich School of Arts and Sciences and codirector of the Petersen Institute for NanoScience and Engineering (PINSE) at Pitt. “We are learning how to reduce electronic circuit elements to single molecules for a new generation of enhanced and more sustainable technologies.” The switch was discovered by experimenting with the rotation of a triangular cluster of three metal atoms held together by a nitrogen atom, which is enclosed entirely within a cage made up entirely of carbon atoms. Petek and his team found that the metal clusters encapsulated within a hollow carbon cage could rotate between several structures under the stimulation of electrons. This rotation changes the molecule’s ability to conduct an electric current, thereby switching among multiple logic states without changing the spherical shape of the carbon cage. Petek says this concept also protects the molecule so it can function without influence from outside chemicals. Because of their constant spherical shape, the prototype molecular switches can be integrated as atom-like building blocks the size of one nanometer (100,000 times smaller than the diameter of a human hair) into massively parallel computing architectures. The prototype was demonstrated using an Sc3N@C80 molecule sandwiched between two electrodes consisting of an atomically flat copper oxide substrate and an atomically sharp tungsten tip. By applying a voltage pulse, the equilateral triangle-shaped Sc3N could be rotated predictably among six logic states.
Swedish University to Take Graphene Out of the Lab
AMikael Fogelström and Sergey Kubatkin are two of the Chalmers researchers investigating the supermaterial graphene. The cryostat in the picture is used to cool graphene samples to one hundredth of a degree above absolute zero. (Image Credit: Jan-Olof Yxell,
Chalmers University of Technology)
Chalmers University of Technology will receive the lion's share of a new Swedish research grant of SEK 40 million for the supermaterial graphene. Following the new financing from the Knut and Alice Wallenberg Foundation, a group of some 30 Swedish graphene researchers will be formed, in a close collaboration between Chalmers and the universities of Uppsala and Linköping. The effort will form the Swedish spearhead in international graphene research – a hot topic ever since the Nobel Physics Prize in 2010. “The money will be used for everything from producing graphene to developing a variety of products, with basic research into experimental and theoretical physics along the way,” says Mikael Fogelström, the project coordinator. The graphene production process needs to be improved and made more reproducible. The researchers will develop reliable synthesis methods designed to produce high-quality graphene surfaces. Following that, the material will be investigated and processed at the nano level, ultimately to be used for specific components with far better performance than today's electronic devices.
Graphene can enable the best quantum resistance standard. This is one of many advances emerging from the active research into graphene at Chalmers. The researchers have already achieved several important breakthroughs with graphene, despite the fact that the material was first produced as recently as 2004. One example is a new standard for the quantum of resistance – a “tuning fork” for calibrating the correct resistance in electrical instruments and devices. State-of-the-art resistance standards are based on silicon or gallium arsenide. These are difficult to manufacture, and the method only works at extremely low temperatures and in large magnetic fields. A new generation of resistance standards based on graphene are at least as accurate as those in use today, while benefitting from being substantially easier to produce and use.
From Solar Paint to Instantly Charged Batteries, IEEE Experts Say the Future Looks Big for Nano
It’s been said that big things come in small packages. But according to experts at the 11th annual IEEE NANO 2011 Conference, some of the technology innovations and devices that could make the biggest impact in our world are so small millions of them could fit on the head of a pin. These game-changing advancements in nanotechnology, or the science of small things, are transforming the way researchers are approaching how to solve some of our world’s greatest challenges. How about solar cells embedded in paint to turn your house into one big solar panel? Or quantum dots that attack cancer, cell by cell, while leaving healthy tissue untouched? Or batteries for mobile phones that charge in seconds instead of hours? “The challenge to making all these nanotechnology applications mainstream comes down to how we affordably and efficiently get them in the hands of people for practical use,” said Jo-Won Lee, IEEE Member and chair professor at the Department of Convergence Nanoscience, Hanyang University in Seoul, South Korea. Traditional manufacturing doesn’t usually work at the nano-level, but there is a better way being developed, he said. It’s called self-assembly, which essentially means the nanodevices build themselves, much like molecules form in nature to create larger systems. IEEE and its members are playing a major role in making nanotechnology work in the real world. For example, the IEEE Nanotechnology Council advances and coordinates work in the field, including the theory, design, and development of nanotechnology and its scientific, engineering, and industrial applications. Dr. Alexander Balandin, IEEE Senior Member, Chair of the Materials Science and Engineering (MS&E) program at the University of California, Riverside and recipient of the IEEE Pioneer of Nanotechnology Award for 2011, offers one intriguing example: “Research is being done to achieve better control of electron interaction with photons, which could lead to much more efficient and less expensive photovoltaic solar cells. This not only benefits existing solar applications, but in the future these nanomaterials could be commercialized as a solar paint that is sprayed on homes and buildings, forever changing the dynamics of our existing electrical grid.” Read a profile of Dr. Balandin here, and watch a clip of IEEE member Jose Delgado-Frias speaking about nanotechnology below.
Nobel Prize in Chemistry Awarded for Discovery of Quasicrystals
The Royal Swedish Academy of Sciences has awarded the Nobel Prize in Chemistry for 2011 to Dan Shechtman, of Technion, the Israel Institute of Technology, in Haifa, Israel “for the discovery of quasicrystals.” In quasicrystals, we find the fascinating mosaics of the Arabic world reproduced at the level of atoms: regular patterns that never repeat themselves. However, the configuration found in quasicrystals was considered impossible, and Dan Shechtman had to fight a fierce battle against established science. The Nobel Prize in Chemistry 2011 has fundamentally altered how chemists conceive of solid matter. On the morning of 8 April 1982, an image counter to the laws of nature appeared in Dan Shechtman’s electron microscope. In all solid matter, atoms were believed to be packed inside crystals in symmetrical patterns that were repeated periodically over and over again. For scientists, this repetition was required in order to obtain a crystal. Shechtman’s image, however, showed that the atoms in his crystal were packed in a pattern that could not be repeated. His discovery was extremely controversial. In the course of defending his findings, he was asked to leave his research group. However, his battle eventually forced scientists to reconsider their conception of the very nature of matter. When scientists describe Shechtman’s quasicrystals, they use a concept that comes from mathematics and art: the golden ratio. This number had already caught the interest of mathematicians in Ancient Greece, as it often appeared in geometry. In quasicrystals, for instance, the ratio of various distances between atoms is related to the golden mean. Following Shechtman’s discovery, scientists have produced other kinds of quasicrystals in the lab and discovered naturally occurring quasicrystals in mineral samples from a Russian river. A Swedish company has also found quasicrystals in a certain form of steel, where the crystals reinforce the material like armor. Scientists are currently experimenting with using quasicrystals in different products such as frying pans and diesel engines.
Nanowire Electronics That Can Be Shaped to Fit Any Surface and Attach to Any Material
Stanford researchers have developed a new method of attaching nanowire electronics to the surface of virtually any object, regardless of its shape or what material it is made of. The method could be used in making everything from wearable electronics and flexible computer displays to high-efficiency solar cells and ultrasensitive biosensors. Nanowire electronics are promising building blocks for virtually every digital electronic device used today, including computers, cameras and cell phones. The electronic circuitry is typically fabricated on a silicon chip. The circuitry adheres to the surface of the chip during fabrication and is extremely difficult to detach, so when the circuitry is incorporated into an electronic device, it remains attached to the chip. But silicon chips are rigid and brittle, limiting the possible uses of wearable and flexible nanowire electronics. The key to the new method is coating the surface of the silicon wafer with a thin layer of nickel before fabricating the electronic circuitry. Nickel and silicon are both hydrophilic, or "water-loving," meaning when they are exposed to water after fabrication of nanowire devices is finished, the water easily penetrates between the two materials, detaching the nickel and the overlying electronics from the silicon wafer.
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The robots, just half a millimeter wide, are composed of microparticles. Confined between two liquids, they assemble themselves into star shapes when an alternating magnetic field is applied. (Credit: Argonne National Lab)
Alexey Snezhko and Igor Aronson, physicists at the U.S. Department of Energy's (DOE) Argonne National Laboratory, have coaxed "micro-robots" to do their bidding. The robots, just half a millimeter wide, are composed of microparticles. Confined between two liquids, they assemble themselves into star shapes when an alternating magnetic field is applied. Snezhko and Aronson can control the robots' movement and even make them pick up, transport and put down other non-magnetic particles—potentially enabling fabrication of precisely designed functional materials in ways not currently possible. Snezhko and Aronson suspended the tiny ferromagnetic particles between two layers of immiscible, or non-mixing, fluids. Without a magnetic field, the particles drift aimlessly or clamp together. But when an alternating magnetic field is applied perpendicular to the liquid surface, they self-assemble into spiky circular shapes that the scientists nicknamed "asters", after the flower. Left to their own devices, the asters don't swim. "But if you apply a second small magnetic field parallel to the surface, they begin to move," said Aronson. "The field breaks the symmetry of the asters' hydrodynamic flow, and the asters begin to swim." By changing the magnetic field, the researchers discovered they could remotely control the asters' motion. "We can make them open their jaws and close them," said Snezhko. "This gives us the opportunity to use these creatures as mini-robots performing useful tasks. You can move them around and pick up and drop objects." The research is a part of the ongoing effort, funded by the DOE, to understand and design active self-assembled materials. These structures can assemble, disassemble, and reassemble autonomously or on command and will enable novel materials capable of multi-tasking and self-repair.
New Way to Write on the Nanoscale
Suenne Kim, Nazanin Bassiri-Gharb, and Yaser Bastani have developed a way to draw nanostructures directly on plastic. (Credit: Georgia Tech)
Using a technique known as thermochemical nanolithography (TCNL), researchers at Georgia Tech have developed a new way to fabricate nanometer-scale ferroelectric structures directly on flexible plastic substrates that would be unable to withstand the processing temperatures normally required to create such nanostructures. The technique, which uses a heated atomic force microscope (AFM) tip to produce patterns, could facilitate high-density, low-cost production of complex ferroelectric structures for energy harvesting arrays, sensors and actuators in nano-electromechanical systems (NEMS) and micro-electromechanical systems (MEMS).
"We can directly create piezoelectric materials of the shape we want, where we want them, on flexible substrates for use in energy harvesting and other applications," said Nazanin Bassiri-Gharb, assistant professor in the School of Mechanical Engineering at the Georgia Institute of Technology. "This is the first time that structures like these have been directly grown with a CMOS-compatible process at such a small resolution. Not only have we been able to grow these ferroelectric structures at low substrate temperatures, but we have also been able to pattern them at very small scales." In addition to the Georgia Tech researchers, the work also involved scientists from the University of Illinois Urbana-Champaign and the University of Nebraska Lincoln. Ultimately, arrays of AFM tips under computer control could produce complete devices, providing an alternative to current fabrication techniques.
Two-Dimensional Graphene Metamaterials and One-Atom-Thick Optical Devices
A graphene waveguide and splitter.
(Image Credit: University of Pennsylvania)
Two University of Pennsylvania engineers have proposed the possibility of two-dimensional metamaterials. These one-atom-thick metamaterials could be achieved by controlling the conductivity of sheets of graphene, which is a single layer of carbon atoms. Professor Nader Engheta and graduate student Ashkan Vakil, both of the Department of Electrical and Systems Engineering in Penn’s School of Engineering and Applied Science, have recently published their theoretical research. The study of metamaterials is an interdisciplinary field of science and engineering that has grown considerably in recent years. It is premised on the idea that materials can be designed so that their overall wave qualities rely not only upon the material they are made of but also on the pattern, shape and size of irregularities, known as “inclusions,” or “meta-molecules” that are embedded within host media. These unusual properties generally have to do with manipulating electromagnetic (EM) or acoustic waves; in this case, it is EM waves in the infrared spectrum. Changing the shape, speed and direction of these kinds of waves is a subfield of metamaterials known as “transformation optics” and may find applications in everything from telecommunications to imaging to signal processing. Engheta and Vakil’s research shows how transformation optics might now be achieved using graphene, a lattice of carbon a single atom thick.
IBM and ETH Zurich Open Collaborative Nanotechnology Center
The Nanotechnology Center includes class 100 (ISO 5) to class 10'000 (ISO 7) cleanroom facilities.
(Image Credit: IBM)
IBM and ETH Zurich, a European science and engineering university, recently opened the Binnig and Rohrer Nanotechnology Center located on the campus of IBM Research – Zurich. The facility is the centerpiece of a 10-year strategic partnership in nanoscience between IBM and ETH Zurich where scientists will research novel nanoscale structures and devices to advance energy and information technologies. The new Center is named for Gerd Binnig and Heinrich Rohrer, the two IBM scientists and Nobel Laureates who invented the scanning tunneling microscope at the Zurich Research Lab in 1981, thus enabling researchers to see atoms on a surface for the first time. Scientists and engineers from IBM and ETH Zurich will pursue joint and independent projects, ranging from exploratory research to applied and near-term projects including new nanoscale devices and device concepts as well as generating insights about their scientific foundations at the atomic level. Three ETH professors and their teams have moved into the new building and will conduct part of their research in nanoscience on a permanent base. Even more ETH researchers will benefit from the partnership and be able to use the excellent infrastructure for various projects. One focus of IBM's research in the Center is put on exploring the "next switch"-- the future building blocks for better, faster and more energy efficient chips and computer systems. For example, IBM scientists are currently exploring semiconducting nanowires--tiny hairlike structures-- to potentially increase the energy efficiency of computing devices by 10 times. In addition, through novel device concepts, such nanowires-transistors could virtually consume zero energy while in passive or standby mode. Additional research areas include micro- and nanoelectromechanical systems, spintronics, organic electronics, carbon-based devices, functional materials, cooling, three-dimensional integration of computer chips, opto-electronics and optical data communication in computers as well as silicon nanophotonics.
Nanomaterial Bulks Up Under Stress
Rather than breaking down, a nanocomposite material stiffens under strain, a finding that in the future may be useful in the development of artificial cartilage.
(Image Credit: Ajayan lab, Rice University)
A synthetic material gets stronger from repeated strain much like the body strengthens bone and muscle after repeated workouts. The trick to stiffening polymer-based nanocomposites with carbon nanotube fillers lies in the complex, dynamic interface between nanostructures and polymers in carefully engineered nanocomposite materials. Researchers at Rice University discovered the interesting property while testing the high-cycle fatigue properties of a composite made by infiltrating vertically aligned, multi-walled nanotubes with polydimethylsiloxane, an inert rubber polymer. Instead of damaging the material, repeatedly loading it seemed to make it stiffer. Using dynamic mechanical analysis (DMA) to test the material, the researchers found that after 3.5 million compressions (five per second) over about a week’s time, the stiffness of the composite had increased by 12 percent and showed the potential for even further improvement. “It took a bit of tweaking to get the instrument to do this,” says Brent Carey, a graduate student at Rice University working in the lab of Pulickel Ajayan, professor of mechanical engineering and materials science and of chemistry at Rice University. “DMA generally assumes that your material isn’t changing in any permanent way. In the early tests, the software kept telling me, ‘I’ve damaged the sample!’ as the stiffness increased. I also had to trick it with an unsolvable program loop to achieve the high number of cycles.” Materials scientists know that metals can strain-harden during repeated deformation, a result of the creation and jamming of defects—known as dislocations—in their crystalline lattice. Polymers, which are made of long, repeating chains of atoms, don’t behave the same way. Researchers are not sure precisely why their synthetic material behaves as it does.
Nanomagnets Offer Food for Thought About Computer Memories
Collage of NIST "nano-eggs" — simulated magnetic patterns in NIST’s egg-shaped nanoscale magnets. Image Credit: Talbott/NIST
Magnetics researchers at the U.S. National Institute of Standards and Technology (NIST) colored lots of eggs recently. Bunnies and children might find the eggs a bit small — in fact, too small to see without a microscope. But these "eggcentric" nanomagnets have another practical use, suggesting strategies for making future low-power computer memories. For a study described in a new paper, NIST researchers used electron-beam lithography to make thousands of nickel-iron magnets, each about 200 nanometers (billionths of a meter) in diameter. Each magnet is ordinarily shaped like an ellipse, a slightly flattened circle. Researchers also made some magnets in three different egglike shapes with an increasingly pointy end. It's all part of NIST research on nanoscale magnetic materials, devices and measurement methods to support development of future magnetic data storage systems. It turns out that even small distortions in magnet shape can lead to significant changes in magnetic properties. Researchers discovered this by probing the magnets with a laser and analyzing what happens to the "spins" of the electrons, a quantum property that's responsible for magnetic orientation. Changes in the spin orientation can propagate through the magnet like waves at different frequencies. The more egg-like the magnet, the more complex the wave patterns and their related frequencies.The shifts are most pronounced at the ends of the magnets. Find out more...
Engineering Professor Examines New Designs for Ultra Fast Nano-Oscillators
Nano-oscillators
Image Credit: University of California, Riverside
Even the smallest devices, assembled at the molecular level, need motors and oscillators. UC Riverside Mechanical Engineering Professor Qing Jiang thinks bundling groups of carbon nanotubes together could make an ultra-efficient and accurate nano-oscillator. In the rapidly developing field of nanotechnology -- doing things at a scale 100,000 times narrower than a human hair -- nanodevices are becoming an increasingly key component in everything from drug delivery to improving or even replacing the microprocessors in computers or optical switches in telecommunications networks. “We’re looking at the very fundamentals of machinery in the nanoscopic world and what it takes to move the components of these machines, ultra-fast, super-efficient and with extreme precision” Jiang said. “A nano-motor generating rotational motion, a nano-oscillator (like a piston) generating linear motion forward and backward. We’re looking at how best to generate these motions in a nano-environment.” Jiang’s earlier work, done mostly with multi-walled carbon nanotube oscillators, in which a narrow nanotube is encased in a larger nanotube, encountered two limitations -- frequency and friction. With increased frequency, beyond the benchmark one gigahertz (a billion cycles per second), increased energy dissipation creates a lot of heat, which reduces the efficiency of the tiny pistons. His current work, with bundles of single-walled carbon nanotubes encased in an additional layer of single-walled carbon nanotubes outperformed their multi-walled counterparts and generated less heat and friction problems.
Nanotechnology Breakthrough in Treating MRSA
Image Credit: IBM
IBM scientists have recently described the application of nanotechnology expertise to healthcare, specifically the treatment of antibiotic-resistant bacteria and infectious diseases like Methicillin-resistant Staphylococcus aureus, known as MRSA. There are two main issues with conventional antibiotics today – one is that they indiscriminately affect all cells – they have no way to tell which ones are infected and which ones are not. Many times it takes multiple cycles of prescribed antibiotics to kill the bacteria. The second problem is that they do not penetrate cells – so the antibiotics surround infected cells while damaging nearby healthy cells, ultimately allowing bacteria to get stronger and become immune to the antibiotics. Further, the remaining antibiotics typically stay in the body and accumulate in the organs, causing damaging side effects. Researchers at IBM have designed special nanostructures that have been proven to tackle these two problems. Once in contact with water, the polymers in these agents self-assemble into new structures that are basically magnetically attracted to bacteria membranes based on their electrostatic interaction. Once they ‘find’ the bacterial-infected cells, they break the membrane walls and destroy the bacteria from within the cell. Since there is no physical attraction to the healthy cells, those remain untouched; they can still transport oxygen throughout the body and combat bacteria on their own. Finally, the nanostructures are biodegradable – once they’ve done their job, they leave the body. Find out more...
