Transforms nanowires into incredibly small transistors for powerful, flexible computers.
Five years after moving from China to Massachusetts, Xiangfeng Duan had earned a PhD from Harvard University in physical chemistry and moved to the forefront of nanotechnology research. Last year he joined Palo Alto, CA-based startup Nanosys as a staff scientist to help create practical technology using semi-conducting nanowires. Duan and his colleagues developed a method for fabricating nanowires two to 100 nanometers in diameter and up to hundreds of micrometers long. They also devised techniques for organizing these nanowires into functional electric circuits. Using these techniques, Duan has built transistors 10 times smaller than conventional ones and has made tiny light-emitting diodes. He has also shown how nanowire arrays can be mounted on flexible substrates, which could lead to foldable or wearable computers. Investors have poured more than $55 million into Nanosis since its founding in 2001, and roughly half the company’s efforts are based on Duan’s research. So the startup’s investors can’t wait to see what Duan will accomplish next using his nanotech bag of tricks.
Invented a novel, high-efficiency engine powered by sound waves.
Scott Backhaus is making waves- powerful acoustic waves that could cut the cost of industrial refrigeration. His tool is a thermoacoustic engine- a helium-filled pipe up to two meters long and 1.5 meters in diameter- that converts heat into sound waves, powering a chiller or producing electricity. When Backhaus began as a postdoc at Los Alamos National Laboratory five years ago, themoacoustic engines were mere lad curiosities whose inefficiency limited their usefulness. Within five months, Backhaus, who is now a technical staff member at Los Alamos, engineered a feedback loop in the pipes that produced 50 percent more power from the same amount of heat. The resulting waves were so strong they wrecked his prototype, but the efficiency boost had suddenly made the technology practical. This spring, industrial-gases firm Praxair tested a thermoacoustic chiller using Backhaus’s approach and intends to sell it for use in converting natural gas into a more easily transportable liquid form. The National Institute of Standards and Technology is also funding the development of Backhaus’s acoustic engines for use in natural-gas power plants.
Fabricates organic semiconductors used in flexible and cheap electronic devices.
Walking through the hallways of Bell Labs- where the transistor was invented more than 55 years ago- with Zhenan Bao, one senses that her brain is in high gear. Bao’s ambition is nothing less than to reinvent the transistor by developing organic semiconductors that should make it possible to put electronics everywhere, in everything from wall-sized displays to price stickers on cereal boxes. Although organic semiconductor circuits can’t match the computing power of silicon chips, they are potentially far cheaper to make. Producing silicon chips typically requires multibillion-dollar fabrication plants, but a modified ink-jet or silkscreen printer can pattern dissolved organic semiconductors on a pliable sheet of plastic. Bao crafted a plastic all-prints circuit in 1997. Collaborating with startup E Ink, she then helped create a prototype of electronic paper, a thin, flexible display. Bao subsequently discovered a new class of organic semiconductors that could enable even more complex circuitry. And she’s now working on still better-performing organics. Indeed, Bao’s efforts are driving the filed almost as quickly as she moves through Bell Lab’s hallowed halls.
Designs coatings to improve implanted medical devices and industrial tools.
Someday soon, Marcela Bilek’s work may be dear to people’s heart. The University of Sydney physics professor has designed microscopically this coatings that enable glass, metal, and other materials to interact more safely with the human body and perform better in industrial settings. One low-friction coating, currently in animal trials, protects the blood-contacting surfaces on implantable medical devices, such as the temporary heart pumps used by heart failure patients. Bilek’s coatings may also have significant industrial applications. Recent tests have shown that they can extend tenfold the life of high-speed cutting implements used by automakers. Having earned an MBA from the Rochester Institute of Technology, Bilek feels comfortable predicting that her coatings could save manufacturers millions of dollars in tool replacement costs. She is also studying how her coatings might improve diagnostic instruments used in medicine.
Turns sea muck into fuel cell power plants.
Turning the muck at the bottom of the ocean into a valuable source of energy, is a lot less improbable than it might seem, thanks to microbiologist Daniel Bond. Three years ago U.S. Navy researchers discovered that a graphite rod dtuck in sea muck generates microwatts of electricity. This past year, Bond helped explain why. The senior research fellow at the University of Massachusetts showed that bacteria collect on the rod, feed on organic compounds in the muck, and transfer electrons to the graphite, creating current. Bond and colleagues have since turned that insight into a practical fuel cell. Bond places the bacteria inside a glass chamber and feeds then organic matter; in response, the bacteria create a usable current. The bacteria in the fuel cell can feed on contaminants such as toluene. Bond’s goal is to optimize the fuel cells to generate large amounts of electricity. If he succeeds, the bacteria-based fuel cells could transform sewage plants into power plants.
Builds microturbines that could become the power plant of choice in many settings.
Michael Bowman is producing prototype turbines just 1.5 meters tall and two meters long that could provide everything from backup power in the office to primary power for remote area of developing countries. The natural-gas microturbine Bowman designed uses a proprietary combustion chamber and electronics to produce 175 kilowatts- enough to supply a small hospital, or about 20 houses. General Electric claims the turbine is more efficient and less polluting than anything already on the market and estimates that it will be commercially available in 2006. Bowman, a mechanical engineer and manager of GE’s energy systems laboratory, says, “We leveraged a lot of GE technology on larger machines to develop a low-cost solution.” And that approach is consisten with his career ambitions: to adapt specialized technologies for massive markets. Bowman’s previous GE designs include a motorized turbocharger that reduces engine startup emissions in diesel locomotives and trucks. His sights are now on an even bigger prize: making hydrogen power practical. Bowman leads 10 researchers who are exploring ways to yse wins and geothermal systems to drive electrolysis, which extracts hydrogen from water. “We have a very novel idea in the process of patenting,” he says, which he hopes could help wean the world off fossil fuels.
Developed new fabrication methods that could slash the cost of chip manufacturing.
There has to be a cheaper way to make computer chips, and Colin Bulthaup thinks he has found it. Current manufacturing involves multibillion-dollar fabrication plants that use time-consuming photolithography methods to painstakingly etch features onto semiconductor microchips. But as an MIT grad student, Bulthaup developed a method that uses a liquid embossing system to directly print patterns of inorganic semiconductors on the chips. And because the technique-which requires no etching- can cheaply deposit multiple layers of complex circuits, even on flexible substrates, it can be used for such applications as inexpensive electronic tags. After earning a graduate degree, Bulthaup and three partners initially raised $7 million to start Sunnyvale, CA-based Kovio, which is aiming to commercialize the technology. Bulthaup predicts his approach will cut the cost of chip manufacture but a factor of 10 and says that electronic devices made with the printing technology will be available in 2005.
Engineered a minimally invasive process to rebuild tissue for breast cancer survivors.
Karen Burg wants to heal the minds and bodies of women who survive breast cancer. The psychological and physical trauma of lumpectomies and mastectomies is bad enough, but many women also undergo reconstructive breast surgery, enduring general anesthesia and risking infection from incisions, implants, and stitches. At the tissue-engineering lab Burg runs at Clemson University, the associate professor of bioengineering has developed a minimally invasive process for rebuilding breast tissue. Burg has designed tiny, degradable synthetic beads on which a patient’s own fat cells can be cultivated. A degradable gel is added to help temporarily bind the beads on which a patients’ own fat cells, which are injected into the damaged tissue. In laboratory tests, injected cells reproduced and meshed with native cells, and the beads decomposed as the new tissue grew to support itself. Burg hopes to begin human trials of the method soon: the National Institutes of Health may provide an infusion of nearly $3 million for the effort. Burg is also assessing ways to apply her tissue-engineering techniques to the repair of ruptured spinal discs.
Formulates business strategy for one of nanotechs leading startups.
Stephen Empdocles wasn’t looking for a career in business developmet, But in helping transform nanotechnology from a largely academic exercise into a fledgling industry, he found one. After earning a PhD in physical chemistry from MIT and joining Quantum Dot of Hayward, CA, and early nanotech startup, Empdocles realized there was a critical lack of people with both business and technical expertise in the nanotech world. The consequence was a gap between scientific realities and market expectations, and Empdocles stepped in to develop the business strategies to bridge the gap. He helped devise novel ways to use nanocrystals for biological testing and played an important role in finding Quantum Dot more than $37 million in venture financing. In 2001 he lfeft Quantum Dot and cofounded Nanosys in Palo Alto, CA. The company’s goal, says Empdocles, director of business development, is to commercialize nanotech’s first blockbuster products within three years. Combining his technical insight and business savvy, Empdocles has identified several candidates, such as building materials impregnated with nano solar cells. Recently, Nanosys signed a deal with Matsushita Electric Works to develop the nano solar-cell technology. Overall, Nanosys has raised $55 million in investments. If Empdocles can pull off that first big product, his transformation from scientist to entrepreneur will be complete.
Designs flight control technology that could lead to unmanned autonomous helicopters.
For Vladislav Gavrilets, mathematics has wings. As a PhD candidate at MIT, he has built an avionics system that enabled a one-and-a-half-meter-long unmanned helicopter to complete programmed flips and rolls without human intervention. The two-time junior chess champion of Kyrgyzstan studied an expert pilot’s strategy for performing aerial maneuvers, modeled it mathematically, and created algorithms to execute it. Then he wired up an onboard, custom flight control box containing sensors, including a Global Positioning System receiver and an altimeter to monitor the helecopter’s position, and a radio that transmitted data to a ground-based processor. Fed with such real-time information, the processor continuously updated flight instructions. Recently, Gavrilets used his algorithms to demonstrate how the helicopter can complete an air show routine. He hopes improved processing will lead to unmanned helicopters that react to unexpected obstacles. Eventually, such helicopters could perform military reconnaissance or film aerial scenes for movies. Gavrilets is now a manager of control systems development at Athena Technologies in Warrenton. VA, which makes miniature autopilots for unmanned aircraft.
Devises processes used to make polymers with improved properties.
For Scott Gaynor, hunting for new polymers in the lab is “just like the hunting I did as a boy: you never know what’s behind the next tree.” As assistant director of the Macromolecular Engineering Laboratory at Carnegie Mellon University, Gaynor discovered catalysts that led to a new technology for synthesizing versatile and customizable polymers. Gaynor then played a lead role in developing the process to make polymers that could be used in everything from coatings to microelectronics to cosmetics. The technology is now being investigated by dozens of manufacturers worldwide for use in commercial applications. The process, “atom transfer radical polymerization,” is more tolerant of water, dust, and other impurities than other polymerization processes, a plus in industrial settings. Gaynor, who holds 10 patents and has three more pending, joined Dow Chemical in 2000, where he has developed new techniques to synthesize variants of common plastics, with improved properties. Gaynor is now preparing light-emitting polymers that could result in video displays that are thinner, sharper, and brighter than current flat-panel liquid-crystal displays.
Shrinks optical circuitry to speed transmissions on phone and Internet networks.
Cary Gunn is changing photonics- the use of laser light for computing and telecommunications. A long-term goal of the field is to etch optical circuitry onto silicon wafers so it can manipulate light the way electronic circuitry manipulates electrons. To make the technology widely useful and cost effective in telecommunications networks, engineers have been trying to decrease the size of optical components and integrate them with electronics on individual chips. When Gunn was a Caltech graduate student, he used proprietary computer simulation tools to design fine-scale optics that enable tiny optical components- one-hundredth the size of conventional ones- that operate with unprecedented precision. The improvement makes it practical to integrate optical and electronic components. Such integrated microprocessors could communicate with the outside world at much higher data rates than separate chips can manage, while using less power. To develop the technology, Gunn and five associates raised $24 million form venture capitalists and started Luxtera in Carlsbad, CA. Gunn, who is vice president, says Luxtera should have integrated chips on the market by next year.
Fashions three-dimensional grids of nanowires that act as electronic circuits.
Chinese-born Yu Huang came to the United States in 1999 to pursue an advanced education in materials science. It didn’t take long, however, before she developed creative new ways to make nanoelectronics. One of her first breakthroughs was a method for controlling the assembly of circuitry made from semiconducing wires less than 100 nanometers in diameter. Huang, who received her PhD in June from Harvard University and is now a Lawrence Livermore fellow at MIT, suspended nanowires made of silicon and other materials in an ethanol solution. She then forced the fluid through tiny channels in a plastic mold, creating parallel nanowire arrays. Using the method, she built nanowire grids that could finction as electronic circuits. She also demonstrated that she could build up layers of arrays, creating three-dimensional circuitry. Huang says her approach, unlike other methods of assembling nanowires, could be scaled up to produce millions of devices at a time. Even though practical products are likely at least a decade away„ several computer chip manufacturers, including Intel, have expressed interest.
Makes higher-density hard drives using magnetic nanomaterials.
Although practical nanotechnologies devices are often portrayed as being light years away, Jordan Katine is making them part of the present. In 1999, Katine demonstrated how to alter a nanomaterial’s magnetic orientation by sending a “spin-polarized” current through it- a current composed of electrons all spinning in the same direction, rather than in random directions as in common electrical current. To exploit this effect and boost the density of magnetic storage, Katine made “nanopillars smaller than 100 nanometers across, composed of a magnetic layer at each end separated by a copper layer. By sending spin-polarized current through the pillar, he got its electrons to spin in the same direction and aligned the magnetic layers; reversing the direction of current flow reversed the electron, which flipped the magnetic layers back. The nanopillars can assume one of two magnetic states, and thus can serve as bits in storage systems. Katine, a research staff member at Hitachi Global Storage Technologies in San Jose, CA, has already used a similar technique to pack more bits onto magnetic recording heads in computer hard drives that Hitachi is selling. Much as the former College Bowl whiz enjoys publishing in Physical Review Letters, he also likes going to Circuit City and saying, “I built this.”
Improves the stability and effectiveness of protein-based drugs.
Proteins are marvels of nature, but because they can be fragile and unstable, many protein-based drugs break down and lose effectiveness. Krishna Kumar, as associate professor of chemistry, heads a Tufts University research team that is engineering better proteins. In one approach, Kumar and his associates chemically alter segments of the proteins, stiffening their structures and improving their stability. In a process that incorporates fluorocarbons like those found in Teflon, the team fabricates proteins that can penetrate human cell membranes to allow the passage of drug molecules. Kumar’s team has received one international patent, and other patents are pending. Several biotechnology and pharmaceutical companies, as well as venture capital firms, are evaluating Kumar’s techniques for their potential to make drugs more effective. If they work, then the flood of new information about the proteins in the human body could soon yield better therapeutics.
David M. Lynn
Synthesizes polymers that are better able to deliver therapeutic genes.
When David Lynn was doing graduate work in chemistry at Caltech, he became fascinated with polymers and their possible biomedical uses. One such possibility is that polymers could deliver therapeutic DNA to cells to treat conditions such as cancer or cystic fibrosis. Other researchers pursuing gene therapy have used modified viruses to carry genetic material into cells, but viruses can provoke serious immune reactions. The right polymer could make a much safer delivery agent, because the immune system is far less likely to perceive it as a threat. As a postdoc at MIT, Lynn developed a process that could synthesize hundreds- or even thousands- of new polymers at once and screen their varying DNA-transferring capabilities. His approach has already identified several new polymers that excel at gene delivery. Now an assistant professor of chemical and biological engineering at the University of Wisconsin- Madison, Lynn has two patents issued or pending relating to his process and has been approached by several companies.
David A. Muller
Images the individual atom that are critical to a transistors electronic properties.
MICROSCOPY MAESTRO David A. Muller knows that many of the features of silicon transistors in computer chips will soon shrink down to the nanoscale. That makes the South African native’s imaging research crucial to the transistor’s future. The electronics industry inserts “dopants,” or impurities, into silicon to control its electrical properties. In the smallest transistors, only one or two dopant atoms could determine the success of a device, which makes it essential that manufacturers understand how dopants function on the nanoscale. Muller has used an electron microscope to directly observe individual dopant atoms of antimony, measuring their structural arrangement, electrical properties, and other traits. Muller, an associate professor of applied and engineering physics at Cornell University, compares the task to locating a few pins in a haystack the size of the United States.
Achieved a breakthrough that could help make quantum computing a reality.
WHILE EXPERIMENTING with ultrasmall superconducting transistors at NEC in Tsukuba, Japan, Yasunobu Nakamura became familiar with quantum computing and had a vision. Each of his transistors featured an island of aluminum just 20 nanometers thick—so small that its state could be altered with a single electron. This exquisite sensitivity was exactly what was needed to create a quantum bit, or qubit, the fundamental element of quantum computing, which promises some day to speed computation exponentially. One of quantum computing’s basic requirements—which had been contemplated for two decades—was controlled operation of a qubit, and Nakamura achieved it in 1999.By applying voltage pulses of varying lengths, he dictated whether the island had an extra pair of electrons (the 1state),no extra electrons (the 0 state),or a combination of the two—a quantum-mechanical state that enables qubits to store far more information than conventional bits. Next, Nakamura and a collaborator got two qubits to interact in a manner that had been predicted but never demonstrated. The challenge ahead is to control coupled qubits long enough— microseconds— to perform meaningful computations. Meanwhile, Nakamura says, people should start preparing some good applications for quantum computers.
Devises time-release polymers to replace multiple vaccine injections.
CHEMICAL ENGINEER Balaji Narasimhan is determined to help prevent common world-wide diseases such as tetanus and diphtheria. These illnesses currently require four to five injections to build up a subject’s immunity, a fact that is particularly troublesome in populations with limited access to health care. Narasimhan, an associate professor at Iowa State University, is trying to achieve the same effects with a single dose, by encapsulating vaccines in specially tailored biodegradable polymers. When injected, the polymers slowly release the vaccines in precise amounts at precise times over a one-year period, thereby maximizing immune response and making booster shots unnecessary. The precision that Narasimhan has achieved in lab tests is better than that for previous drug encapsulation systems. Narasimhan is also devising noninteractive polymers to deliver fragile proteins involved in cancer therapies. One advantage is that his polymers resist water, and thus degradation, better than other drug delivery materials. Narasimhan expects both systems to be ready for human testing within five years. Before his work with polymer-based drug delivery,Narasimhan and researchers from the Swiss chemical company Clariant invented a more efficient process for making photoresists—polymers used in the manufacture of computer chips. Clariant is now operating a pilot photoresist production facility in New Jersey that uses this process.
Fights credit card forgery with glass-bead “keys”.
WHEN Acredit card company asked the MIT Media Lab to develop a technique to produce card identifiers that, unlike magnetic stripes, would be extremely difficult to forge, graduate student Ravikanth Pappu devised a cheap and simple solution. He embeds hundreds of glass beads into dime- size epoxy tokens. When a laser shines on a token, its beads scatter the light in a unique pattern that can be digitally stored as a fingerprint or “key.” Retailers could use readers to check patterns against keys in a secure database. Pappu says there is no known technology that can counterfeit the tokens or their keys. Now a principal at ThingMagic in Cam- bridge, MA, which is developing “embedded intelligence” as well as radio frequency identification technologies, Pappu says credit card companies are calling, interested in building tokens into their cards. The technique could also be used for tamper-resistant packaging, or to create identifiers for computer chips. According to Neil Gershenfeld, Pappu’s MIT advisor, cryptographers are often very critical of new ideas, but they have “welcomed this new approach.”
Ainissa G. Ramirez
Formulated an advanced universal solder for electronics and optics.
AINISSA RAMIREZ discovered a long-sought prize of metallurgy: a universal solder that can bond metals to ceramics, glass, diamonds, and, notably, the oxide materials used in semiconductor fabrication. Researchers had been hunting for such a compound for decades: the limitations of available solders have often meant electronic- and optical-device failures. After earning a PhD in materials science at Stanford University and joining Lucent Technologies’ Bell Labs in 1998,Ramirez found that mixing certain rare-earth elements, particularly lutetium, into solder metals vastly improved their bonding capabilities. Her solder is the first that can join all kinds
Of inorganic materials with high-strength bonds, and has the potential for extensive use in the electronics, optoelectronics, and microelectromechanical -systems (MEMS) industries. Ramirez also devised thin-film coatings that lessen damage caused to MEMS components by thermal expansion during operation, and she fabricated alloys that were key to Bell Labs’making a high-speed all-optical switch. Now an assistant professor of mechanical engineering at Yale University, Ramirez finds it odd that metals are “often over-looked” as a field for innovation. “These materials are fundamental,” she points out.
Adds smarts to high-voltage power lines so they can deliver more electricity.
ELECTRIC-POWER grids are often categorized as the world’s largest machines, but they are not the most sophisticated. Grid operators have little data on how weather, shifting electricity consumption, and other factors affect power flows minute to minute over the grids’ high-voltage main lines. So to be safe, utilities cap the power a line carries at well below its physical limits—a drawback, given rising electricity demands. To increase capacity, grids need more smarts, and that’s what Christian Rehtanz gave them, at Zürich, Switzerland-based ABB. Rehtanz devised algorithms that use information from sensors distributed around the grid to monitor a power line—or several lines in a transmission corridor—and calculate in real time how much power it can safely carry. He then led a team that turned these algorithms into a commercial monitoring, protection, and control system for utilities, dubbed PSGuard. Norwegian utility Statnet is already testing Rehtanz’s hardware and software on a massive high-voltage corridor to Sweden, and Rehtanz predicts Statnet will be pushing 10 percent more megawatts by year’s end— potentially enough to supply electricity to an additional 100,000 homes. Rehtanz has since powered up, too; he now leads technology development for ABB’s 8,000-person global power systems business.
Constructs small fuel cells to efficiently power laptop computers.
LAPTOP-COMPUTER users are still slaves to batteries that fade after a few hours. Manfred Stefener, managing director and founder of SFC Smart Fuel Cell in Munich, is leading the way to an alternative: small fuel cartridges that use methanol to generate electricity, emitting only water vapor, carbon dioxide, and heat. Stefener’s company and German laptop maker Medion have partnered to develop and commercialize an energy docking station, which will provide up to 10 hours of power before needing a new fuel cartridge. While it will add some bulk—the product will be docked under the laptop—“They are delivering where other companies have not,” says Robert Hockaday, founder of Energy Related Devices, which is also developing micro fuel cells. Stefener,a chemical engineer, is working on business questions too, such as how customers can easily obtain replacement cartridges. The company is also commercializing its fuel cell system to power other applications, such as traffic signals. And Stefener says the company is working on a fuel cell that can be integrated right into the laptop, avoiding the bulky docking station.
Writes software that could alleviate air congestion and lead to far fewer delays at airports.
FORGET ABOUT the need to build more runways; Claire Tomlin’s computer models and software could eliminate airport congestion. The assistant professor of aeronautics and astronautics at Stanford University has created prototype software that allows planes to detect one another, fly closer together, avoid bad weather, and automatically maneuver to avoid midair collisions. Using the system, air traffic controllers might achieve far greater efficiencies, which should translate into fewer delays for passengers. Although testing for commercial air traffic use is still a decade away, Boeing researchers in St. Louis, MO, already use Tomlin’s software to ensure safe coordination of groups of unmanned aerial vehicles. Tomlin’s innovations make her a leader in a new field that provides both optimal solutions to complex logistical problems and ultrasafe software control of mechanical systems, says Richard Murray ,a mechanical engineer at Caltech. Tomlin’s methods, he says, are critical for anyone who “cares about verifying that systems do what they are supposed to do.” Her advanced software won’t be ready for use in civilian aircraft for at least 10 years, but because of her work, change is already in the air.
Built a tiny device that greatly speeds up DNA sequencing.
STEPHEN TURNER admits he’s a compulsive inventor: “Whenever I see a device, I think about how to make it better.” At 12,Turner used wires, batteries, and wood to make a light switch his parakeet could operate. As a Cornell University postdoc, he built a minuscule gadget that significantly speeds up the sequencing of DNA. The nano device is just big enough to hold one DNA molecule, one polymerase molecule, and assorted nucleotides. The polymerase copies the DNA using fluorescently labeled bases as building blocks. An optical detector reads the bases, one at a time, as they are assembled. Turner says the approach is more cost effective thanstandard sequencing methods because it requires fewer DNA strands and reagents, and it is potentially 1,000 times faster. Moreover, a million of these nano devices could fit on a chip the size of a penny,supporting a million reactions simultaneously. Turner predicts that the technology could sequence the entire genome of an individual in hours, which would bring much closer the idea of genetic-based personalized medicine. Turner is now chief scientific officer at Nanofluidics, a Cornell spinoff in Ithaca, NY, where he plans to commercialize the technology within five years.
S. Travis Waller
Writes algorithms that determine why traffic jams form and how to ease them.
WHEN S. Travis Waller, a native of tiny Ironton, OH, first experienced the traffic snarls of Chicago, he was shocked. Clearing congestion is now his work. The fundamental research tool in his field is software that models traffic flow, but until recently, the models were capable of representing only static traffic conditions. Waller wrote algorithms that allow for dynamic modeling of changing conditions. As a postdoc at Northwestern University, he led the development of modeling tools based on the algorithms and made them available on the Web. Waller and others are using these tools to analyze traffic-congested areas and specify the most effective long-term investments in infrastructure improvements. Now an assistant professor of civil engineering at the University of Texas at Austin, Waller is also devising an online routing system that uses onboard computers to tell drivers which routes offer the quickest paths given current traffic patterns. Hoping to identify the conditions that slow traffic, he is working with the city of Chicago to test the system by tracking transponder-equipped buses. Eventually, the system could feed data to a central controller that would change red lights to green to improve traffic flow.
Fabricates nanotube crystals that can route optical telecommunications signals faster than competing chips.
THE UNIVERSITY of Paderborn’s Ralf Wehrspohn is one of Germany’s youngest physics professors and an expert in manipulating light. One key to future optical devices could be crystals made from materials such as silicon or aluminum oxide. Four years ago, at the Max Planck Institute, Wehrspohn constructed and patented a stamp- like tool embossed with billions of microscopic pyramids that impose a grid of tiny perforations on the materials. He and his colleagues then used acids to burrow into the perforations, creating a perfect array of holes. They melted a metal or polymer over the template, forming nanotubes of specific depths and widths in the holes. Light passing through the resulting nanoarray can be “steered” by electrical fields. Wehrspohn is now collaborating with Infineon Technologies to develop an all-optical chip that reroutes communications signals faster than current routers. He is also working on a compact sensor that measures how light flow is altered by alcohol in a person’s breath.
Assembles nanowires that could revolutionize lasers and computers.
IF NANOELECTRONICS is ever to fulfill its promise of supplying vastly smaller and more powerful computers, researchers will need to invent the right materials. No one knows what those will be, but University of California, Berkeley, assistant chemistry professor Peidong Yang believes inorganic nanowires offer tantalizing possibilities .Such wires are only a few nanometers in diameter, but they can be several micrometers long; Yang says those dimensions make them “naturals” for integrating nanoelectronics with larger-scale devices. Using a light-emitting nanowire, Yang has built a tiny laser, an invention that could revolutionize ultradense data storage. He has also used a combination of semiconducting materials to form single nanowires that could act as tiny light-emitting diodes, and has made nanowires that show promise as highly efficient thermoelectric materials for converting heat into electricity. Still, Yang acknowledges that challenges remain before these creations yield commercial devices. Chief among them, he says, is finding ways to assemble millions of nanowires into a desired device. Yang is pursuing several research projects to achieve just that.