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Breakthrough Chip Technology Lights the Path to Exascale Computing
IBM's new CMOS Integrated Silicon Nanophotonics chip technology integrates electrical and optical devices on the same piece of silicon, enabling computer chips to communicate using pulses of light (instead of electrical signals). (Image Credit: IBM)
IBM scientists have unveiled a new chip technology that integrates electrical and optical devices on the same piece of silicon, enabling computer chips to communicate using pulses of light (instead of electrical signals), resulting in smaller, faster and more power-efficient chips than is possible with conventional technologies. The new technology, called CMOS Integrated Silicon Nanophotonics, is the result of a decade of development at IBM's global Research laboratories. The patented technology will change and improve the way computer chips communicate -- by integrating optical devices and functions directly onto a silicon chip, enabling over 10X improvement in integration density than is feasible with current manufacturing techniques. IBM anticipates that Silicon Nanophotonics will dramatically increase the speed and performance between chips, and further the company's ambitious Exascale computing program, which is aimed at developing a supercomputer that can perform one million trillion calculations -- or an Exaflop -- in a single second. An Exascale supercomputer will be approximately one thousand times faster than the fastest machine today.
“The development of the Silicon Nanophotonics technology brings the vision of on-chip optical interconnections much closer to reality,” said Dr. T.C. Chen, vice president, Science and Technology, IBM Research. “With optical communications embedded into the processor chips, the prospect of building power-efficient computer systems with performance at the Exaflop level is one step closer to reality.” In addition to combining electrical and optical devices on a single chip, the new IBM technology can be produced on the front-end of a standard CMOS manufacturing line and requires no new or special tooling. With this approach, silicon transistors can share the same silicon layer with silicon nanophotonics devices. To make this approach possible, IBM researchers have developed a suite of integrated ultra-compact active and passive silicon nanophotonics devices that are all scaled down to the diffraction limit – the smallest size that dielectric optics can afford.
Building 3-D Molecular Structures
(Image Credit: University of Nottingham)
Scientists at the University of Nottingham have made a major breakthrough that could help shape the future of nanotechnology, by demonstrating for the first time that 3-D molecular structures can be built on a surface. The discovery could prove a significant step forward towards the development of new nano devices such as cutting-edge optical and electronic technologies and even molecular computers. The team of chemists and physicists at Nottingham have shown that by introducing a ‘guest’ molecule they can build molecules upwards from a surface rather than just 2-D formations previously achieved. A natural biological process known as ‘self-assembly’ meant that once the scientists introduced other molecules on to a surface their host then spontaneously arranged them into a rational 3-D structure. Professor Neil Champness said: “It is the molecular equivalent of throwing a pile of bricks up into the air and then as they come down again they spontaneously build a house. “Until now this has only been achievable in 2-D, so to continue the analogy the molecular ‘bricks’ would only form a path or a patio but our breakthrough now means that we can start to build in the third dimension. It’s a significant step forward to nanotechnology.” Previously, scientists have employed a technique found in nature of using hydrogen bonds to hold DNA together to build two-dimensional molecular structure.
The new process involved introducing a guest molecule -- in this case a ‘buckyball’ or C60 -- on to a surface patterned by an array of tetracarboxylic acid molecules. The spherical shape of the buckyballs means they sit above the surface of the molecule and encourage other molecules to form around them. It offers scientists a completely new and controlled way of building up additional layers on the surface of the molecule. The work is the culmination of four years’ of research led by Professors Champness and Beton from the School of Chemistry and the School of Physics and Astronomy, which has been funded with a total of £3.5 million from the Engineering and Physical Sciences Research Council.
Intricate and Curving 3D Nanostructures Created
Twisting spires are one of the 3D shapes researchers at the University of Michigan were able to develop using a new manufacturing process. (Image Credit: University of Michigan, A. John Hart)
Twisting spires, concentric rings, and gracefully bending petals are a few of the new three-dimensional shapes that University of Michigan engineers can make from carbon nanotubes using a new manufacturing process. The process is called “capillary forming,” and it takes advantage of capillary action, the phenomenon at work when liquids seem to defy gravity and spontaneously travel up a drinking straw. The new miniature shapes have the potential to harness the exceptional mechanical, thermal, electrical, and chemical properties of carbon nanotubes in a scalable fashion, said A. John Hart, an assistant professor in the Department of Mechanical Engineering and in the School of Art & Design. The 3D nanotube structures could enable countless new materials and microdevices, including probes that can interface with individual cells, novel microfluidic devices, and lightweight materials for aircraft and spacecraft.
“It’s easy to make carbon nanotubes straight and vertical like buildings,” Hart said. “It hasn’t been possible to make them into more complex shapes. Assembling nanostructures into three-dimensional shapes is one of the major goals of nanotechnology and nanomanufacturing. The method of capillary forming could be applied to many types of nanotubes and nanowires, and its scalability is very attractive for manufacturing.” Hart’s method starts by patterning a thin metal film on a silicon wafer. This film is the iron catalyst that facilitates the growth of vertical carbon nanotube “forests” in patterned shapes. It’s a sort of template. Rather than pattern the catalyst into uniform shapes such as circles and squares, Hart's team patterns a variety of unique shapes such as hollow circles, half circles, and circles with smaller ones cut from their centers. The shapes are arranged in different orientations and groupings, creating different templates for later forming the 3D structures using capillary action. Find out more...
Graphene Pioneers Awarded Nobel Prize
Professor Andre Geim and Professor Konstantin Novoselov of the University of Manchester have been awarded the highest accolade in the scientific world for their pioneering work with the world’s thinnest material. (Image Credit: University of Manchester)
A thin flake of ordinary carbon, just one atom thick, lies behind this year’s Nobel Prize in Physics. Andre Geim and Konstantin Novoselov have shown that carbon in such a flat form has exceptional properties that originate from the remarkable world of quantum physics. Graphene is a form of carbon. As a material it is completely new – not only the thinnest ever but also the strongest. As a conductor of electricity it performs as well as copper. As a conductor of heat it outperforms all other known materials. It is almost completely transparent, yet so dense that not even helium, the smallest gas atom, can pass through it. Carbon, the basis of all known life on earth, has surprised us once again. Geim and Novoselov extracted the graphene from a piece of graphite such as is found in ordinary pencils. Using regular adhesive tape they managed to obtain a flake of carbon with a thickness of just one atom. This at a time when many believed it was impossible for such thin crystalline materials to be stable.
However, with graphene, physicists can now study a new class of two-dimensional materials with unique properties. Graphene makes experiments possible that give new twists to the phenomena in quantum physics. Also a vast variety of practical applications now appear possible including the creation of new materials and the manufacture of innovative electronics. Graphene transistors are predicted to be substantially faster than today’s silicon transistors and result in more efficient computers. Since it is practically transparent and a good conductor, graphene is suitable for producing transparent touch screens, light panels, and maybe even solar cells. When mixed into plastics, graphene can turn them into conductors of electricity while making them more heat resistant and mechanically robust. This resilience can be utilised in new super strong materials, which are also thin, elastic and lightweight. In the future, satellites, airplanes, and cars could be manufactured out of the new composite materials.
This year’s Laureates have been working together for a long time. Konstantin Novoselov, 36, first worked with Andre Geim, 51, as a PhD-student in the Netherlands. He subsequently followed Geim to the United Kingdom. Both of them originally studied and began their careers as physicists in Russia. Now they are both professors at the University of Manchester in the United Kingdom. Find out more...
Making Music at the Nano Scale
(Image Credit: University of Twente)
Earlier musical instruments with these minimal dimensions only produced tones that are inaudible to humans. But thanks to ingenious construction techniques, students from the University of Twente in the Netherlands have succeeded in producing scales that are audible when amplified. To do so, they made use of the possibilities offered by micromechanics: the construction of moving structures with dimensions measured in micrometres (a micrometre is a thousandth of a millimetre). These miniscule devices can be built thanks to the ultra-clean conditions in a 'clean room', and the advanced etching techniques that are possible there. "You can see comparable technology used in the Wii games computer for detecting movement, or in sensors for airbags", says PhD student Johan Engelen, who devised and led the student project. The tiny musical instrument is made up of springs that are only a tenth of the thickness of a human hair, and vary in length from a half to a whole millimetre. A mass of a few dozen micrograms is hung from these springs. The mass is set in motion by so-called 'comb drives': miniature combs that fit together precisely and shift in relation to each other, so 'plucking' the springs and creating sounds. The mass vibrates with a maximum deflection of just a few micrometres. This minimal movement can be accurately measured, and produces a tone. Each tone has its own mass spring system, and six tones fit on a microchip. By combining a number of chips, a wider range of tones can be achieved. "The tuning process turned out to be the greatest challenge", says Engelen. "We can learn a lot from this project for the construction of other moving structures. Above all, this is a great project for introducing students to micromechanics and clean room techniques." The video below shows a recent concert using the technology.
Research Gives Insight into Using Graphene in Electronics
A visualization of the nanoscale interaction between a semiconducting substrate (below) and graphene. (Credit: Joe Lyding, U. Illinois)
New findings from the laboratory of Beckman Institute for Advanced Science and Technology (University of Illinois at Urbana-Champaign) researcher Joe Lyding are providing valuable insight into graphene, a single two-dimensional layer of graphite with numerous electronic and mechanical properties that make it attractive for use in electronics. Lyding, who heads the Nanoelectronics and Nanomaterials group at Beckman, and his lab report using a dry deposition method they developed to deposit pieces of graphene on semiconducting substrates and on the electronic character of graphene at room temperature they observed using the method. The researchers wrote this of graphene’s potential, especially as compared to its elemental cousin, carbon nanotubes, for use in electronics and other applications: “It exhibits the quantum hall effect, even at room temperature, and its optical transparency is directly related to the fine structure constant. Graphene is more and more being thought of as a fairly strong and elastic membrane (with an associated potential as a material for NEMS applications). Unlike carbon nanotubes, graphene can be patterned using standard e-beam lithographic techniques, making it an attractive prospect for use in semiconductor devices.” To reach that goal, issues associated with graphene must be overcome, and the research gives insight into a much-needed step in that direction: understanding substrate-graphene interactions toward integration into future nanoelectronic devices. The project investigated the electronic character of the underlying substrate of graphene at room temperature and reports on “an apparent electronic semitransparency at high bias of the nanometer-sized monolayer graphene pieces observed using an ultrahigh vacuum scanning tunneling microscope (UHV-STM) and corroborated via first-principles studies.” This semitransparency was made manifest by observation of the substrate atomic structure through the graphene. Find out more...
Nano-coated Cotton Filters Third World Water
A scanning electron microscope image of the silver nanowires in which the cotton is dipped during the process of constructing a filter. The large fibers are cotton.(Credit: Stanford University)
By dipping plain cotton cloth in a high-tech broth full of silver nanowires and carbon nanotubes, Stanford University researchers have developed a new high-speed, low-cost filter that could easily be implemented to purify water in the developing world. Instead of physically trapping bacteria as most existing filters do, the new filter lets them flow on through with the water. But by the time the pathogens have passed through, they have also passed on, because the device kills them with an electrical field that runs through the highly conductive "nano-coated" cotton. In lab tests, over 98 percent of Escherichia coli bacteria that were exposed to 20 volts of electricity in the filter for several seconds were killed. Multiple layers of fabric were used to make the filter 2.5 inches thick. "This really provides a new water treatment method to kill pathogens," said Yi Cui, an associate professor of materials science and engineering. "It can easily be used in remote areas where people don't have access to chemical treatments such as chlorine." Cholera, typhoid and hepatitis are among the waterborne diseases that are a continuing problem in the developing world. Cui said the new filter could be used in water purification systems from cities to small villages. Find out more...
First Step Towards Electronic DNA Sequencing: Translocation Through Graphene Nanopores
University of Pennsylvania researchers developed a carbon-based, nanoscale platform to electrically detect single DNA molecules. Electric fields push tiny DNA strands through atomically-thin graphene nanopores that ultimately may sequence DNA bases by their unique electrical signature. (Credit: University of Pennsylvania; Art: Robert Johnson)
Researchers at the University of Pennsylvania have developed a new, carbon-based nanoscale platform to electrically detect single DNA molecules. Using electric fields, the tiny DNA strands are pushed through nanoscale-sized, atomically thin pores in a graphene nanopore platform that ultimately may be important for fast electronic sequencing of the four chemical bases of DNA based on their unique electrical signature. The pores, burned into graphene membranes using electron beam technology, provide Penn physicists with electronic measurements of the translocation of DNA. “We were motivated to exploit the unique properties of graphene — a two-dimensional sheet of carbon atoms — in order to develop a new nanopore electrical platform that could exhibit high resolution,” said Marija Drndi, associate professor in the Department of Physics and Astronomy in Penn’s School of Arts and Sciences. “High resolution of graphene nanopore devices is expected because the thickness of the graphene sheet is smaller than the distance between two DNA bases. Graphene has previously been used for other electrical and mechanical devices, but up until now it has not been used for DNA translocation." The research team had made graphene nanopores in a study completed two years ago and in this study put the pores to work. Graphene nanopore devices developed by the Penn team work in a simple manner. The pore divides two chambers of electrolyte solution and researchers apply voltage, which drives ions through the pores. Ion transport is measured as a current flowing from the voltage source. DNA molecules, inserted into the electrolyte, can be driven single file through such nanopores. Find out more...
How Butterflies’ Wings Could Cut Bank Fraud
University of Cambridge scientists have discovered a way of mimicking the stunningly bright and beautiful colours found on the wings of tropical butterflies. The findings could have important applications in the security printing industry, helping to make bank notes and credit cards harder to forge. The striking iridescent colours displayed on beetles, butterflies and other insects have long fascinated both physicists and biologists, but mimicking nature's most colourful, eye-catching surfaces has proved elusive. This is partly because rather than relying on pigments, these colours are produced by light bouncing off microscopic structures on the insects' wings. Mathias Kolle, working with Professor Ullrich Steiner and Professor Jeremy Baumberg of the University of Cambridge, studied the Indonesian Peacock or Swallowtail butterfly (Papilio blumei), whose wing scales are composed of intricate, microscopic structures that resemble the inside of an egg carton. Because of their shape and the fact that they are made up of alternate layers of cuticle and air, these structures produce intense colours.
Using a combination of nanofabrication procedures - including self-assembly and atomic layer deposition - Kolle and his colleagues made structurally identical copies of the butterfly scales, and these copies produced the same vivid colours as the butterflies' wings. According to Kolle: "We have unlocked one of nature's secrets and combined this knowledge with state-of-the-art nanofabrication to mimic the intricate optical designs found in nature." "Although nature is better at self-assembly than we are, we have the advantage that we can use a wider variety of artificial, custom-made materials to optimise our optical structures." As well as helping scientists gain a deeper understanding of the physics behind these butterflies' colours, being able to mimic them has promising applications in security printing. "These artificial structures could be used to encrypt information in optical signatures on banknotes or other valuable items to protect them against forgery. We still need to refine our system but in future we could see structures based on butterflies wings shining from a £10 note or even our passports," he says. (Note: video above courtesy of University of Cambridge.) Find out more...
NIST Scientists Gain New Core Understanding of Nanoparticles
Schematic of a spherical magnetite nanoparticle shows the unexpected variation in magnetic moment between the particle's interior and exterior when subjected to a strong magnetic field. The core's moment (black lines in magenta region) lines up with the field's (light blue arrow), while the exterior's moment (black arrows in green region) forms at right angles to it.
(Image Credit: NIST)
While attempting to solve one mystery about iron oxide-based nanoparticles, a research team working at the National Institute of Standards and Technology (NIST) stumbled upon another one. But once its implications are understood, their discovery may give nanotechnologists a new and useful tool. The nanoparticles in question are spheres of magnetite so tiny that a few thousand of them lined up would stretch a hair’s width, and they have potential uses both as the basis of better data storage systems and in biological applications such as hyperthermia treatment for cancer. A key to all these applications is a full understanding of how large numbers of the particles interact magnetically with one another across relatively large distances so that scientists can manipulate them with magnetism. The team applied a magnetic field to nanocrystals composed of 9 nm-wide particles, made by collaborators at Carnegie Mellon University. The field caused the particles to line up like iron filings on a piece of paper held above a bar magnet. But when the team looked closer using the neutron beam, what they saw revealed a level of complexity never seen before. “When the field is applied, the inner 7 nm-wide ‘core’ orients itself along the field’s north and south poles, just like large iron filings would,” says Kathryn Krycka, a researcher at the NIST Center for Neutron Research. “But the outer 1 nm ‘shell’ of each nanoparticle behaves differently. It also develops a moment, but pointed at right angles to that of the core.” In a word, bizarre. But potentially useful. The shells are not physically different than the interiors; without the magnetic field, the distinction vanishes. But once formed, the shells of nearby particles seem to heed one another: A local group of them will have their shells’ moments all lined up one way, but then another group’s shells will point elsewhere. This finding leads Krycka and her team to believe that there is more to be learned about the role that particle interaction has on determining internal, magnetic nanoparticle structure—perhaps something nanotechnologists can harness. “The effect fundamentally changes how the particles would talk to each other in a data storage setting,” Krycka says. “If we can control it—by varying their temperature, for example, as our findings suggest we can—we might be able to turn the effect on and off, which could be useful in real-world applications.” Find out more...
Spiders at the Nanoscale
The latest installment in DNA nanotechnology has arrived: A molecular nanorobot dubbed a "spider" and labeled with green dyes traverses a substrate track built upon a DNA origami scaffold. It journeys towards its red-labeled goal by cleaving the visited substrates, thus exhibiting the characteristics of an autonomously moving, behavior-based robot at the molecular scale.
(Image Source: CALTECH Press Release incorporating Image Credit: Paul Michelotti)
A team of scientists from Columbia University, Arizona State University, the University of Michigan, and the California Institute of Technology (Caltech) have programmed an autonomous molecular "robot" made out of DNA to start, move, turn, and stop while following a DNA track. Shrinking robots down to the molecular scale would provide, for molecular processes, the same kinds of benefits that classical robotics and automation provide at the macroscopic scale. Molecular robots, in theory, could be programmed to sense their environment (say, the presence of disease markers on a cell), make a decision (that the cell is cancerous and needs to be neutralized), and act on that decision (deliver a cargo of cancer-killing drugs). Or, like the robots in a modern-day factory, they could be programmed to assemble complex molecular products. The power of robotics lies in the fact that once programmed, the robots can carry out their tasks autonomously, without further human intervention. Milan N. Stojanovic, a faculty member in the Division of Experimental Therapeutics at Columbia University, led the project and teamed up with Winfree and Hao Yan, professor of chemistry and biochemistry at Arizona State University and an expert in DNA nanotechnology, and with Nils G. Walter, professor of chemistry and director of the Single Molecule Analysis in Real-Time (SMART) Center at the University of Michigan in Ann Arbor, for what became a modern-day self-assembly of like-minded scientists with the complementary areas of expertise needed to tackle a tough problem. Find out more...
New ‘Nanoburrs’ Could Help Fight Heart Disease
Image Credit: MIT
Researchers at MIT and Harvard Medical School have built targeted nanoparticles that can cling to artery walls and slowly release medicine, an advance that potentially provides an alternative to drug-releasing stents in some patients with cardiovascular disease. The particles, dubbed “nanoburrs” because they are coated with tiny protein fragments that allow them to stick to target proteins, can be designed to release their drug payload over several days. The nanoburrs are targeted to a specific structure, known as the basement membrane, which lines the arterial walls and is only exposed when those walls are damaged. Therefore, the nanoburrs could be used to deliver drugs to treat atherosclerosis and other inflammatory cardiovascular diseases. They are one of the first such targeted particles that can precisely home in on damaged vascular tissue, says Omid Farokhzad, associate professor at Harvard Medical School. Farokhzad and MIT Institute Professor Robert Langer have previously developed nanoparticles that seek out and destroy tumorsThe researchers hope the particles could become a complementary approach that can be used with vascular stents, which are the standard of care for most cases of clogged and damaged arteries, or in lieu of stents in areas not well suited to them, such as near a fork in the artery.
Smart Coating Opens Door To Safer Hip, Knee and Dental Implants
Cross-sectional transmission electron microscope image of the functionally graded smart coating with nano-silver particles distributed throughout the entire thickness of the coating. Image Credit: North Carolina State University
Researchers at North Carolina State University have developed a “smart coating” that helps surgical implants bond more closely with bone and ward off infection. When patients have hip, knee or dental replacement surgery, they run the risk of having their bodies reject the implant. But the smart coating developed at NC State mitigates that risk by fostering bone growth into the implant. The coating creates a crystalline layer next to the implant, and a mostly amorphous outer layer that touches the surrounding bone. The amorphous layer dissolves over time, releasing calcium and phosphate, which encourages bone growth. The researchers have also incorporated silver nanoparticles throughout the coating to ward off infections. Currently, implant patients are subjected to an intense regimen of antibiotics to prevent infection immediately following surgery. However, the site of the implant will always remain vulnerable to infection. But by incorporating silver into the coating, the silver particles will act as antimicrobial agents as the amorphous layer dissolves. This will not only limit the amount of antibiotics patients will need following surgery, but will provide protection from infection at the implant site for the life of the implant. Moreover, the silver is released more quickly right after surgery, when there is more risk of infection, due to the faster dissolution of the amorphous layer of the coating. Silver release will slow down while the patient is healing. Find out more... and explore other nanotechnology medical applications...
Celebrate NanoDays - March 27 - April 4, 2010
NanoDays is a U.S.-based festival of educational programs about nanoscale science and engineering and its potential impact on the future. NanoDays events are organized by participants in the Nanoscale Informal Science Education Network (NISE Net), and take place at over 200 science museums, research centers, and universities across the country. Since 2008, NanoDays celebrations across the United States have combined simple hands-on activities for young people with events exploring current research for adults. This year it is easier than ever to find a museum, university, or research organization that is hosting an event. A list of organizations participating in NanoDays 2010 has been compiled to help those interested in participating.
Rice, Korean Collaboration Produces Printable Tag that Could Replace Bar Codes
RFID tags printed through a new roll-to-roll process could replace bar codes and make checking out of a store a snap. Image Credit: Gyou-Jin Cho/Sunchon National University
Long lines at store checkouts could be history if a new technology created in part at Rice University comes to pass. Rice researchers, in collaboration with a team led by Gyou-jin Cho at Sunchon National University in Korea, have come up with an inexpensive, printable transmitter that can be invisibly embedded in packaging. It would allow a customer to walk a cart full of groceries or other goods past a scanner on the way to the car; the scanner would read all items in the cart at once, total them up and charge the customer's account while adjusting the store's inventory. More advanced versions could collect all the information about the contents of a store in an instant, letting a retailer know where every package is at any time. The technology described in the journal "IEEE Transactions on Electron Devices" is based on a carbon-nanotube-infused ink for ink-jet printers first developed in the Rice University lab of James Tour, the T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science. The ink is used to make thin-film transistors, a key element in radio-frequency identification (RFID) tags that can be printed on paper or plastic. Find out more...
Smart Polymers Perform Nano-Acrobatics
One result of the new research is that scientists will now be able to exploit the COMPcc portion of a polymer to wrap around a Vitamin D molecule in order to stimulate its tissue-regenerating power. Genetically engineered copolymers have applications in everything from artificial therapeutics, biocatalysts, scaffolds, and cells for medicine, to sustainable energy and environmental remediation. Credit: New York University
Researchers are finding remarkable ways in which bioengineered paired macromolecules can be made to self-assemble, disassemble, and more -- and then biodegrade when they’ve finished their work. The key to these macromolecules -- called block copolymers -- is their ability to self-assemble when exposed to discrete external stimuli. Self-assembly can occur as a function of temperature or pH, for example. And it is not necessarily a permanent change; it can be reversed. Genetically engineered copolymers have applications in everything from artificial therapeutics, biocatalysts, scaffolds, and cells for medicine, to sustainable energy and environmental remediation. For four years, Jin Kim Montclare and researchers at the Polytechnic Institute of New York University have been developing block copolymers from scratch using recombinant DNA and putting them through biochemical hoops. The group’s work, published recently in the journal ChemBioChem, involves block copolymers comprising elastin alternating with COMPcc. The former is a pentapeptide whose amino-acid constituents can assemble into a beta spiral structure as a function of temperature, pH, or salinity. COMPcc, which stands for “cartilage oligomeric matrix protein coil coiled,” is a pentamer arranged as five helixes that can contort into an arrangement that produces a hydrophobic core the way one might create a cylindrical cavity by stacking garden hoses on a deck -- thus the odd “coiled coil” nomenclature. COMPcc has the ability to bind small water-insoluble molecules such as Vitamin D within its hydrophobic core. The possibilities are manifold. “That central pore can potentially bind chemicals that are hard to deliver as drugs because they are normally not water soluble,” says Montclare. For example COMPcc can bind to Vitamin D, a non-dissolving molecule that happens to have profound implications for regenerative tissue and serves as a signaling hormone for the promotion of tissue differentiation into cartilage and bone. And COMPcc can “live” in a copolymer with elastin, synthetics, or other coiled coil-based materials that self-assemble into gels or more organized forms like scaffolding, which can be used for tissue regeneration. Find out more...
Rice Physicists Kill Cancer with 'Nanobubbles'
By using lasers and nanoparticles Jason Hafner, left, and Dmitri Lapotko have discovered a new technique for singling out individual diseased cells and destroying them with tiny explosions. Credit: Jeff Fitlow/Rice University
Using lasers and nanoparticles, scientists at Rice University have discovered a new technique for singling out individual diseased cells and destroying them with tiny explosions. The scientists used lasers to make "nanobubbles" by zapping gold nanoparticles inside cells. In tests on cancer cells, they found they could tune the lasers to create either small, bright bubbles that were visible but harmless or large bubbles that burst the cells. Nanobubbles are created when gold nanoparticles are struck by short laser pulses. The short-lived bubbles are very bright and can be made smaller or larger by varying the power of the laser. Because they are visible under a microscope, nanobubbles can be used to either diagnose sick cells or to track the explosions that are destroying them. In the current study, Lapotko and Rice colleague Jason Hafner, associate professor of physics and astronomy and of chemistry, tested the approach on leukemia cells and cells from head and neck cancers. They attached antibodies to the nanoparticles so they would target only the cancer cells, and they found the technique was effective at locating and killing the cancer cells. Find out more...
Watching Crystals Grow May Lead to Faster Electronic Devices
Conventional theory says when films are being formed at the atomic scale, atoms land on top of each other and form mounds or "islands" and feel an energetic "pull" from other atoms that prevents them from hopping off the island's edges and crystallizing into smooth sheets. The result is rough spots on the thin films used to produce semiconductors. Cornell University-led researchers eliminated this pull by shortening the bonds between their particles. But they still saw particles hesitate at the island's edges.
Image Credit: Rajesh Ganapathy, Sharon Gerbode, Mark Buckley, and Itai Cohen - Cornell University
The quest for faster electronic devices recently got something more than a little bump up in technological knowhow. Scientists at Cornell University, Ithaca, N.Y. discovered that the thin, smooth, crystalline sheets needed to make semiconductors, which are the foundation of modern computers, might be grown into smoother sheets by managing the random darting motions of the atomic particles that affect how the crystals grow. Led by assistant professor of physics Itai Cohen at Cornell, researchers recreated conditions of layer-by-layer crystalline growth using particles much bigger than atoms, but still small enough that they behave like atoms. Similar to using beach balls to model the behavior of sand, scientists used a solution of tiny plastic spheres 50 times smaller than a human hair to reproduce the conditions that lead to crystallization on the atomic scale. With this precise modeling, they could watch how crystalline sheets grow. Using an optical microscope, the scientists could watch exactly what their "atoms"--actually, micron-sized silica particles suspended in fluid--did as they crystallized. What's more, they were able to manipulate single particles one at a time and test conditions that lead to smooth crystal growth. The video below is sped up by a factor of about 20. Video Credit: John Savage, Rajesh Ganapathy, and Itai Cohen - Cornell University. Find out more...
Nanodragsters Hit the Street
Image Credit: Rice University
The latest work in a series of molecular machines that began with 2005's nanocar has produced what Rice University scientists James Tour and Kevin Kelly call a nanodragster for its characteristic hot-rod shape, with small wheels on a short axle in the front and large wheels on a long axle in the back. Their research is another step toward functional nanomachines that can be custom-built and set to work in microelectronics and other applications. What those wheels are made of matters most. Early nanocars rolled on simple carbon 60 molecules, aka buckyballs. But they were a drag, literally, as they would only turn on a gold surface in high heat, about 200 degrees Celsius. The Rice team found in previous research that wheels made of p-carborane, a cluster of carbon and boron atoms, operate at much lower temperatures. But they're more difficult to image with a scanning tunneling microscope because of their much weaker interaction with metallic surfaces. The key to making nanodragsters was putting p-carborane wheels in the front and buckyballs in the back, getting the advantages of both. The front wheels roll easier, while the buckyballs grip the gold roadway well enough to be imaged. And the vehicle operates at a much lower temperature than previous nanovehicles. Find out more...
Identifying Molecules in Infrared
For the first time, researchers can use infrared spectroscopy to determine what type of bonds protein molecules contain and to identify materials. The new technique has been sought to overcome several limitations of the current, standard technique. Image Credit: Hatice Altug, Electrical Engineering Department, Boston University
An interdisciplinary team of researchers has created a new, ultra-sensitive technique to analyze life-sustaining protein molecules. The technique may profoundly change the methodology of biomolecular studies and chart a new path to effective diagnostics and early treatment of complex diseases. Researchers from Boston University and Tufts University near Boston recently demonstrated an infrared spectroscopy technique that can directly identify the "vibrational fingerprints" of extremely small quantities of proteins, the machinery involved in maintaining living organisms. The new technique exploits nanotechnology to overcome several limitations of current, conventional techniques used to study biomolecules. Previous bio-molecular study methods commonly use fluorescence spectroscopy, where biomolecules are labeled with very bright fluorescence tags to track how efficiently they interact with each other. Understanding interactions is important for medical drug research. Molecules consist of atoms bonded to each other with springs. Depending on the mass of atoms, how stiff these springs are, or how the atoms' springs are arranged, the molecules rotate and vibrate at specific frequencies similar to a guitar string that vibrates at specific frequencies depending on the string length. These resonant frequencies are molecule specific and they mostly occur in the infrared frequency range of the electromagnetic spectrum. The sensitivity of infrared spectroscopy previously had been too low to detect these vibrations, particularly from small quantities of samples. Find out more...
At Stanford, Nanotubes + Ink + Paper = Instant Battery
Stanford University scientists are harnessing nanotechnology to quickly produce ultra-lightweight, bendable batteries and supercapacitors in the form of everyday paper. Simply coating a sheet of paper with ink made of carbon nanotubes and silver nanowires makes a highly conductive storage device, said Yi Cui, assistant professor of materials science and engineering. "Society really needs a low-cost, high-performance energy storage device, such as batteries and simple supercapacitors," he said. Like batteries, capacitors hold an electric charge, but for a shorter period of time. However, capacitors can store and discharge electricity much more rapidly than a battery.
Above: Post doctoral students in the lab of Prof. Yi Cui, Materials Science and Engineering, light up a diode from a battery made from treated paper, similar to what you would find in a copy machine. The paper batteries are treated with a nanotube ink, baked and folded into electrical generating sources like the one wrapped in foil seen here.
(Video Credit: Stanford University)
"These nanomaterials are special," Cui said. "They're a one-dimensional structure with very small diameters." The small diameter helps the nanomaterial ink stick strongly to the fibrous paper, making the battery and supercapacitor very durable. The paper supercapacitor may last through 40,000 charge-discharge cycles – at least an order of magnitude more than lithium batteries. The nanomaterials also make ideal conductors because they move electricity along much more efficiently than ordinary conductors, Cui said. Cui had previously created nanomaterial energy storage devices using plastics. His new research shows that a paper battery is more durable because the ink adheres more strongly to paper (answering the question, "Paper or plastic?"). Find out more...
Nanowires Key to Future Transistors, Electronics
As depicted in this illustration, tiny particles of a gold-aluminum alloy were alternately heated and cooled inside a vacuum chamber, and then silicon and germanium gases were alternately introduced. As the gold-aluminum bead absorbed the gases, it became "supersaturated" with silicon and germanium, causing them to precipitate and form wires. (Image Source: Purdue University, Birck Nanotechnology Center/Seyet LLC)
A new generation of ultrasmall transistors and more powerful computer chips using tiny structures called semiconducting nanowires is closer to reality after a key discovery by researchers at IBM, Purdue University and the University of California at Los Angeles. The researchers have learned how to create nanowires with layers of different materials that are sharply defined at the atomic level, which is a critical requirement for making efficient transistors out of the structures. "Having sharply defined layers of materials enables you to improve and control the flow of electrons and to switch this flow on and off," said Eric Stach, an associate professor of materials engineering at Purdue. Electronic devices are often made of "heterostructures," meaning they contain sharply defined layers of different semiconducting materials, such as silicon and germanium. Until now, however, researchers have been unable to produce nanowires with sharply defined silicon and germanium layers. Instead, this transition from one layer to the next has been too gradual for the devices to perform optimally as transistors. The new findings point to a method for creating nanowire transistors. Whereas conventional transistors are made on flat, horizontal pieces of silicon, the silicon nanowires are "grown" vertically. Because of this vertical structure, they have a smaller footprint, which could make it possible to fit more transistors on an integrated circuit, or chip, Stach said. New technologies will be needed for industry to maintain Moore's law, an unofficial rule stating that the number of transistors on a computer chip doubles about every 18 months, resulting in rapid progress in computers and telecommunications. Doubling the number of devices that can fit on a computer chip translates into a similar increase in performance. However, it is becoming increasingly difficult to continue shrinking electronic devices made of conventional silicon-based semiconductors . Find out more...
New Study Confirms Exotic Electric Properties of Graphene
This illustration shows the tip of a scanning tunneling microscope approaching an undulating sheet of perfect graphene. The exotic substance is 10 times stronger than steel and conducts electricity better than any known material at room temperature. Both physicists and nanoscientists are studying graphene and exploring its potential applications. (Image Source: Vanderbilt Univeristy; Image Credit: Calvin Davidson, British Carbon Group)
First, it was the soccer-ball-shaped molecules dubbed buckyballs. Then it was the cylindrically shaped nanotubes. Now there is graphene: a remarkably flat molecule made of carbon atoms arranged in hexagonal rings much like molecular chicken wire. It is 10 times stronger than steel and conducts electricity better than any other known material at room temperature. These and graphene’s other exotic properties have attracted the interest of physicists, who want to study them, and nanotechnologists, who want to exploit them to make novel electrical and mechanical devices. Although graphene is the first truly two-dimensional crystalline material that has been discovered, over the years scientists have put considerable thought into how two-dimensional gases and solids should behave. They have also succeeded in creating a close approximation to a two-dimensional electron gas by bonding two slightly different semiconductors together. Electrons are confined to the interface between the two and their motions are restrained to two dimensions. When such a system is cooled down to less than one degree above absolute zero and a strong magnetic field is applied, then the fractional quantum Hall effect appears. Since scientists figured out how to make graphene five years ago, they have been trying to get it to exhibit this effect with only marginal success. The best way to understand it is to think of the electrons in graphene as a forming a (very thin) sea of charge. When the magnetic field is applied, it generates whirlpools in the electron fluid. Because electrons carry a negative charge, these vortices have a positive charge. Find out more...
Tiny Light Beam Budges Nanoscale Object
Scanning electron micrograph of two thin, flat rings of silicon nitride, each 190 nanometers thick and mounted a millionth of a meter apart. Under the right conditions optical forces between the two rings are enough to bend the thin spokes and pull the rings toward one another, changing their resonances enough to act as an optical switch. Image Credit: Cornell Nanophotonics Group
With a bit of leverage, researchers have used a very tiny beam of light with as little as 1 milliwatt of power to move a silicon structure up to 12 nanometers. That’s enough to completely switch the optical properties of the structure from opaque to transparent, they report.
The technology could have applications in the design of nanoscale devices with moving parts—known as micro-electromechanical systems (MEMS)—and micro-optomechanical systems (MOMS), which combine moving parts with photonic circuits, says Michal Lipson, associate professor of electrical and computer engineering at Cornell University. Light can be thought of as a stream of particles that can exert a force on whatever they strike. The sun doesn’t knock you off your feet because the force is very small, but at the nanoscale it can be significant. “The challenge is that large optical forces are required to change the geometry of photonic structures,” Lipson explained. Find out more...
