Jewel-Toned Organic Phosphorescent Crystals: A New Class of Light-Emitting Material

University of Michigan researcher Jinsang Kim and his colleagues have developed a new class of material that shines with phosphorescence -- a property that has previously been seen only in non-organic compounds or organometallics.

Kim and his colleagues made metal-free organic crystals that are white in visible light and radiate blue, green, yellow and orange when triggered by ultraviolet light. By changing the materials' chemical composition, the researchers can make them emit different colors.

The new luminous materials, or phosphors, could improve upon current organic light-emitting diodes (OLEDs) and solid-state lighting. Bright, low-power OLEDs are used in some small screens on cell phones or cameras. At this time, they aren't practical for use in larger displays because of material costs and manufacturing issues.

The OLEDs of today aren't 100 percent organic, or made of carbon compounds. The organic materials used in them must be spiked with metal to get them to glow.

"Purely organic materials haven't been able to generate meaningful phosphorescence emissions. We believe this is the first example of an organic that can compete with an organometallic in terms of brightness and color tuning capability," said Kim, an associate professor of materials science and engineering, chemical engineering, macromolecular science and engineering, and biomedical engineering.

This work is newly published online inNature Chemistry.

The new phosphors exhibit"quantum yields" of 55 percent. Quantum yield, a measure of a material's efficiency and brightness, refers to how much energy an electron dissipates as light instead of heat as it descends from an excited state to a ground state. Current pure organic compounds have a yield of essentially zero.

In Kim's phosphors, the light comes from molecules of oxygen and carbon known as"aromatic carbonyls," compounds that produce phosphorescence, but weakly and under special circumstances such as extremely low temperatures. What's unique about these new materials is

that the aromatic carbonyls form strong halogen bonds with halogens in the crystal to pack the molecules tightly. This arrangement suppresses vibration and heat energy losses as the excited electrons fall back to the ground state, leading to strong phosphorescence.

"By combining aromatic carbonyls with tight halogen bonding, we achieve phosphorescence that is much brighter and in practical conditions," said Onas Bolton, a co-author of this paper who recently received his Ph.D. in Materials Science and Engineering.

This new method offers an easier way to make high-energy blue organic phosphors, which are difficult to achieve with organometallics.

Organic light emitting diodes are lighter and cheaper to manufacture than their non-organic counterparts, which are made primarily of ceramics. Today's OLEDs still contain small amounts of precious metals, though. These new compounds can bring the price down even further, because they don't require precious metals. They're made primarily of inexpensive carbon, oxygen, chlorine and bromine.

"This is in the beginning stage, but we expect that it will not be long before our simple materials will be available commercially for device applications," Kim said."And we expect they will bring a big change in the LED and solid-state lighting industries because our compounds are very cheap and easy to synthesize and tune the chemical structure to achieve different colors and properties."

Former doctoral student Kangwon Lee discovered the unique properties of these materials while developing a biosensor -- a compound that detects biological molecules and can be used in medical testing and environmental monitoring. The phosphors have applications in this area as well. After Lee's discovery, Bolton developed the metal-free pure-organic phosphors.

The paper is titled"Activating efficient phosphorescence from purely-organic materials by crystal design." In addition to Kim, Bolton, and Lee, other contributors are: former postdoctoral researcher Hyong-Jun Kim in the Department of Materials Science and Engineering and recent Chemical Engineering graduate Kevin Y. Lin. This work is partly funded by the National Science Foundation and the National Research Foundation of Korea.

The university is pursuing patent protection for the intellectual property, and is seeking commercialization partners to help bring the technology to market.

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Better Way to Diagnose Pneumonia

Called PneumoniaCheck, the device created at Georgia Tech is a solution to the problem of diagnosing pneumonia, which is a major initiative of the U.S. Centers for Disease Control and Prevention (CDC).

Pneumonia, an inflammation of the lungs, kills about 2.4 million people each year. The problem is particularly devastating in Africa, Southeast Asia and the Eastern Mediterranean, where a child dies of pneumonia every 15 seconds.

Developed by mechanical engineering students, graduate business students and faculty at Georgia Tech, PneumoniaCheck will be commercially launched this month to healthcare professionals through the startup company, MD Innovate Inc.

"Georgia Tech created a simple and new device to detect the lung pathogens causing pneumonia," said David Ku, Georgia Tech Regents' Professor of Mechanical Engineering, Lawrence P. Huang Chair Professor for Engineering Entrepreneurship in the College of Management, and Professor of Surgery at Emory University."It has the potential to save more lives than any other medical device."

Last year, Ku was asked by the head of virology at the CDC to develop a quick and economical way to diagnose pneumonia, particularly in developing nations where it is a leading cause of death among children.

Ku challenged a group of mechanical engineering and bioengineering graduate students to develop an accurate device for diagnosing pneumonia. Current sampling methods using the mouth and nose are only 40 percent effective. The samples are typically contaminated by bacteria in the mouth, which leads to misdiagnosis and an incorrect prescription of antibiotics.

In developing nations, many children with respiratory infections fail to receive adequate care, and the overuse of antibiotics has led to an increase in drug-resistant bacteria. An accurate, easy-to-use and widely available new diagnostic test could improve identification of bacterial respiratory infection in children, reducing the inappropriate use of antibiotics and the long-term negative impacts of drug resistance, according to a recent article inNaturetitled"Reducing the global burden of acute lower respiratory infections in children: The contributions of new diagnostics."

As a Tech graduate student, Tamera Scholz and her peers developed the solution -- PneumoniaCheck.

The device contains a plastic tube with a mouthpiece. A patient coughs into the device to fill up a balloon-like upper airway reservoir before the lung aerosols go into a filter. Using fluid mechanics, PneumoniaCheck separates the upper airway particles of the mouth from the lower airway particles coming from the lungs.

"It's interesting because it's so simple," said Scholz (M.S. '10 Mechanical Engineering), who is now an engineer for Newell Rubbermaid."It's not a fancy contraption. It's a device that patients cough into and through fluid mechanics it separates upper and lower airway aerosols. Through each iteration, it got simpler.… I like that I will be able to see it make a difference in my lifetime."

Once the device was developed, Taylor Bronikowski and a group of Georgia Tech M.B.A. students from the College of Management started developing a business plan for PneumoniaCheck that starts locally and grows globally. They used the device as a test case to develop a Triple Bottom Line company in India that could result in financial profits, environmental sustainability and social benefits, such as jobs and healthcare.

"Our goal is to provide better medicine at a cost savings to patients and hospitals," Bronikowski said."We wanted a worldwide solution, so patients in developing nations can afford it."

Bronikowksi, Ku and Sarah Ku formed the startup company, MD Innovate Inc., in 2010 to manufacture the device in large quantities and organize distribution and commercialization. The device is now being used in pneumonia studies at Grady Memorial Hospital in downtown Atlanta and the Atlanta Veterans Administration Medical Center, Ku said.

The FDA has cleared PneumoniaCheck for sale in the U.S. The device is licensed but its patent is pending. The company will start selling PneumoniaCheck in the U.S. in January and it could hit other countries in two years, Ku said.

"It's a great feeling, working on something that has the potential to save thousands of lives," Bronikowski said.

On the horizon, Ku and future Georgia Tech graduate students will be developing a simple and effective method for diagnosing pneumonia in regions without healthcare facilities or basic infrastructure.

For more information, visit:http://www.mdinnov8.com/

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New Stretchable Solar Cells Will Power Artificial Electronic 'Super Skin'

Super skin, indeed.

"With artificial skin, we can basically incorporate any function we desire," said Bao, a professor of chemical engineering."That is why I call our skin 'super skin.' It is much more than what we think of as normal skin."

The foundation for the artificial skin is a flexible organic transistor, made with flexible polymers and carbon-based materials. To allow touch sensing, the transistor contains a thin, highly elastic rubber layer, molded into a grid of tiny inverted pyramids. When pressed, this layer changes thickness, which changes the current flow through the transistor. The sensors have from several hundred thousand to 25 million pyramids per square centimeter, corresponding to the desired level of sensitivity.

To sense a particular biological molecule, the surface of the transistor has to be coated with another molecule to which the first one will bind when it comes into contact. The coating layer only needs to be a nanometer or two thick.

"Depending on what kind of material we put on the sensors and how we modify the semiconducting material in the transistor, we can adjust the sensors to sense chemicals or biological material," she said.

Bao's team has successfully demonstrated the concept by detecting a certain kind of DNA. The researchers are now working on extending the technique to detect proteins, which could prove useful for medical diagnostics purposes.

"For any particular disease, there are usually one or more specific proteins associated with it -- called biomarkers -- that are akin to a 'smoking gun,' and detecting those protein biomarkers will allow us to diagnose the disease," Bao said.

The same approach would allow the sensors to detect chemicals, she said. By adjusting aspects of the transistor structure, the super skin can detect chemical substances in either vapor or liquid environments.

Regardless of what the sensors are detecting, they have to transmit electronic signals to get their data to the processing center, whether it is a human brain or a computer.

Having the sensors run on the sun's energy makes generating the needed power simpler than using batteries or hooking up to the electrical grid, allowing the sensors to be lighter and more mobile. And having solar cells that are stretchable opens up other applications.

A recent research paper by Bao, describing the stretchable solar cells, will appear in an upcoming issue ofAdvanced Materials. The paper details the ability of the cells to be stretched in one direction, but she said her group has since demonstrated that the cells can be designed to stretch along two axes.

The cells have a wavy microstructure that extends like an accordion when stretched. A liquid metal electrode conforms to the wavy surface of the device in both its relaxed and stretched states.

"One of the applications where stretchable solar cells would be useful is in fabrics for uniforms and other clothes," said Darren Lipomi, a graduate student in chemical engineering in Bao's lab and lead author of the paper.

"There are parts of the body, at the elbow for example, where movement stretches the skin and clothes," he said."A device that was only flexible, not stretchable, would crack if bonded to parts of machines or of the body that extend when moved." Stretchability would be useful in bonding solar cells to curved surfaces without cracking or wrinkling, such as the exteriors of cars, lenses and architectural elements.

The solar cells continue to generate electricity while they are stretched out, producing a continuous flow of electricity for data transmission from the sensors.

Bao said she sees the super skin as much more than a super mimic of human skin; it could allow robots or other devices to perform functions beyond what human skin can do.

"You can imagine a robot hand that can be used to touch some liquid and detect certain markers or a certain protein that is associated with some kind of disease and the robot will be able to effectively say, 'Oh, this person has that disease,'" she said."Or the robot might touch the sweat from somebody and be able to say, 'Oh, this person is drunk.'"

Finally, Bao has figured out how to replace the materials used in earlier versions of the transistor with biodegradable materials. Now, not only will the super skin be more versatile and powerful, it will also be more eco-friendly.

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Engineering Atomic Interfaces for New Electronics

For an electron moving from one material toward the other, this space is where it can join other electrons, which together can create current, magnetism or even light.

A multi-institutional team has made fundamental discoveries at the border regions, called interfaces, between oxide materials. Led by University of Wisconsin-Madison materials science and engineering professor Chang-Beom Eom, the team has discovered how to manipulate electrons in oxide interfaces by inserting a single layer of atoms. The researchers also have discovered unusual electron behaviors at these engineered interfaces.

Their work, which is sponsored by the National Science Foundation, is published Feb. 18 in the journalScienceand could allow researchers to further study and develop interfaces with a wide array of properties.

Eom's team blends theorists and experimentalists, including UW-Madison physics professor Mark Rzchowski and collaborators at the University of Nebraska-Lincoln, University of Michigan, Argonne National Laboratory and Brookhaven National Laboratory.

The researchers used two pieces of precisely grown strontium titanate, which is a type of oxide, or compound with oxygen as a fundamental element. Between the pieces, the researchers inserted a one-atom-thick layer of one of five rare-earth elements, which are important components in the electronics industry.

The team found that the rare-earth element layer creates an electron gas that has some interesting characteristics. The gas actually behaves more like an electron"liquid," since the electrons move more in tandem, or in correlation, than a gas normally does.

"If you take two materials, each has different characteristics, and if you put them together, at their interface you may find something unexpected," Eom says.

This research is the first demonstration of strong correlation among electrons at an oxide interface. The electron layer displayed distinct characteristics depending on the particular rare-earth element the team used. Materials with larger ionic radii, such as lanthanum, neodymium and praseodymium, are conducting, whereas materials with smaller radii, including samarium and yttrium, are insulating.

The insulating elements form an electron gas that can be compared to a thick liquid, somewhat like honey. The higher viscosity (basically, thickness) means the electrons can't move around as freely, making them more insulating. Conversely, the conducting elements form a gas that is a"liquid" more like gasoline; the viscosity is lower, so the electrons can move more freely and are better conductors.

Prior to this research, scientists knew extra electrons could reside at interfaces, but they didn't realize the complexity of how the electrons then behaved together at those interfaces.

The discovery of liquid-like behavior in the electron layer could open up an entire field of interfacial engineering for other scientists to explore, as well as new applications that take advantage of electron interactions. Since Eom and his colleagues developed an understanding of the basic physics behind these behaviors, their work could be expanded to create not only conductive or insulating interfaces, but also magnetic or optical ones.

Though scientists previously have looked at semiconductor interfaces, Eom's team is the first to specifically address those that use oxide interfaces to control conducting states with a single atomic layer. Oxides make up a class of materials including millions of compounds, and each has its own unique set of properties. The ability to manipulate various oxide interfaces could give rise to new generations of materials, electronics and other devices.

"This advancement could make a broad impact in fields even beyond physics, materials or chemistry," Eom says."People can use the idea that an interface made from a single atomic layer of different ions can be used to create all kinds of properties."

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Toward Computers That Fit on a Pen Tip: New Technologies Usher in the Millimeter-Scale Computing Era

And a compact radio that needs no tuning to find the right frequency could be a key enabler to organizing millimeter-scale systems into wireless sensor networks. These networks could one day track pollution, monitor structural integrity, perform surveillance, or make virtually any object smart and trackable.

Both developments at the University of Michigan are significant milestones in the march toward millimeter-scale computing, believed to be the next electronics frontier.

Researchers are presenting papers on each at the International Solid-State Circuits Conference (ISSCC) in San Francisco. The work is being led by three faculty members in the U-M Department of Electrical Engineering and Computer Science: professors Dennis Sylvester and David Blaauw, and assistant professor David Wentzloff.

Bell's Law and the promise of pervasive computing

Nearly invisible millimeter-scale systems could enable ubiquitous computing, and the researchers say that's the future of the industry. They point to Bell's Law, a corollary to Moore's Law. (Moore's says that the number of transistors on an integrated circuit doubles every two years, roughly doubling processing power.)

Bell's Law says there's a new class of smaller, cheaper computers about every decade. With each new class, the volume shrinks by two orders of magnitude and the number of systems per person increases. The law has held from 1960s' mainframes through the '80s' personal computers, the '90s' notebooks and the new millennium's smart phones.

"When you get smaller than hand-held devices, you turn to these monitoring devices," Blaauw said."The next big challenge is to achieve millimeter-scale systems, which have a host of new applications for monitoring our bodies, our environment and our buildings. Because they're so small, you could manufacture hundreds of thousands on one wafer. There could be 10s to 100s of them per person and it's this per capita increase that fuels the semiconductor industry's growth."

The first complete millimeter-scale system

Blaauw and Sylvester's new system is targeted toward medical applications. The work they present at ISSCC focuses on a pressure monitor designed to be implanted in the eye to conveniently and continuously track the progress of glaucoma, a potentially blinding disease. (The device is expected to be commercially available several years from now.)

In a package that's just over 1 cubic millimeter, the system fits an ultra low-power microprocessor, a pressure sensor, memory, a thin-film battery, a solar cell and a wireless radio with an antenna that can transmit data to an external reader device that would be held near the eye.

"This is the first true millimeter-scale complete computing system," Sylvester said.

"Our work is unique in the sense that we're thinking about complete systems in which all the components are low-power and fit on the chip. We can collect data, store it and transmit it. The applications for systems of this size are endless."

The processor in the eye pressure monitor is the third generation of the researchers' Phoenix chip, which uses a unique power gating architecture and an extreme sleep mode to achieve ultra-low power consumption. The newest system wakes every 15 minutes to take measurements and consumes an average of 5.3 nanowatts. To keep the battery charged, it requires exposure to 10 hours of indoor light each day or 1.5 hours of sunlight. It can store up to a week's worth of information.

While this system is miniscule and complete, its radio doesn't equip it to talk to other devices like it. That's an important feature for any system targeted toward wireless sensor networks.

A unique compact radio to enable wireless sensor networks

Wentzloff and doctoral student Kuo-Ken Huang have taken a step toward enabling such node-to-node communication. They've developed a consolidated radio with an on-chip antenna that doesn't need the bulky external crystal that engineers rely on today when two isolated devices need to talk to each other. The crystal reference keeps time and selects a radio frequency band. Integrating the antenna and eliminating this crystal significantly shrinks the radio system. Wentzloff's is less than 1 cubic millimeter in size.

He and Huang's key innovation is to engineer the new antenna to keep time on its own and serve as its own reference. By integrating the antenna through an advanced CMOS process, they can precisely control its shape and size and therefore how it oscillates in response to electrical signals.

"Antennas have a natural resonant frequency for electrical signals that is defined by their geometry, much like a pure audio tone on a tuning fork," Wentzloff said."By designing a circuit to monitor the signal on the antenna and measure how close it is to the antenna's natural resonance, we can lock the transmitted signal to the antenna's resonant frequency."

"This is the first integrated antenna that also serves as its own reference. The radio on our chip doesn't need external tuning. Once you deploy a network of these, they'll automatically align at the same frequency."

The researchers are now working on lowering the radio's power consumption so that it's compatible with millimeter-scale batteries.

Greg Chen, a doctoral student in the Department of Electrical Engineering and Computer Science, presents"A Cubic-Millimeter Energy-Autonomous Wireless Intraocular Pressure Monitor." The researchers are collaborating with Ken Wise, the William Gould Dow Distinguished University Professor of Electrical Engineering and Computer Science on the packaging of the sensor, and with Paul Lichter, chair of the Department of Ophthalmology and Visual Sciences at the U-M Medical School, for the implantation studies. Huang presents"A 60GHz Antenna-Referenced Frequency-Locked Loop in 0.13μm CMOS for Wireless Sensor Networks." This research is funded by the National Science Foundation. The university is pursuing patent protection for the intellectual property, and is seeking commercialization partners to help bring the technology to market.

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Plants That Can Move Inspire New Adaptive Structures

Mechanical engineering professor Kon-Well Wang presented the team's latest work Feb. 19 at the American Association for the Advancement of Science's 2011 Annual Meeting in Washington D.C. Wang is the Stephan P. Timoshenko Collegiate Professor of Mechanical Engineering and chair of the Department of Mechanical Engineering.

"This is quite different from other traditional adaptive materials approaches," Wang said."In general, people use solid-state materials to make adaptive structures. This is really a unique concept inspired by biology."

Researchers at U-M and Penn State University are studying how plants like the Mimosa can change shape, and they're working to replicate the mechanisms in artificial cells. Today, their artificial cells are palm-size and larger. But they're trying to shrink them by building them with microstructures and nanofibers. They're also exploring how to replicate the mechanisms by which plants heal themselves.

"We want to put it all together to create hyper-cellular structures with circulatory networks," Wang said.

The Mimosa is among the plant varieties that exhibit specialized"nastic motions," large movements you can see in real time with the naked eye, said Erik Nielsen, assistant professor in the U-M Department of Molecular, Cellular and Developmental Biology.

The phenomenon is made possible by osmosis, the flow of water in and out of plants' cells. Triggers such as touch cause water to leave certain plant cells, collapsing them. Water enters other cells, expanding them. These microscopic shifts allow the plants to move and change shape on a larger scale.

It's hydraulics, the researchers say.

"We know that plants can deform with large actuation through this pumping action," Wang said."This and several other characteristics of plant cells and cell walls have inspired us to initiate ideas that could concurrently realize many of the features that we want to achieve for adaptive structures."

Nielsen believes nastic movements might be a good place to start trying to replicate plant motions because they don't require new growth or a reorganization of cells.

"These rapid, nastic motions are based on cells and tissues that are already there," Nielsen said."It's easy for a plant to build new cells and tissues during growth, but it's not as easy to engineer an object or machine to completely change the way it's organized. We hope studying these motions can inform us about how to make efficient adaptive materials that display some of the same types of flexibility that we see in biological systems."

When this technology matures, Wang said it could enable robots that change shape like elephant trunks or snakes to maneuver under a bridge or through a tunnel, but then turn rigid to grab a hold of something. It also could lead to morphing wings that would allow airplanes to behave more like birds, changing their wing shape and stiffness in response to their environment or the task at hand.

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New High-Resolution Method for Imaging Below the Skin Using a Liquid Lens

Rolland presented her findings at the 2011 annual meeting of the American Association for the Advancement of Science in Washington, D.C., on Feb. 19.

"My hope is that, in the future, this technology could remove significant inconvenience and expense from the process of skin lesion diagnosis," Rolland says."When a patient walks into a clinic with a suspicious mole, for instance, they wouldn't have to have it necessarily surgically cut out of their skin or be forced to have a costly and time-consuming MRI done. Instead, a relatively small, portable device could take an image that will assist in the classification of the lesion right in the doctor's office."

The device accomplishes this using a unique liquid lens setup developed by Rolland and her team for a process known as Optical Coherence Microscopy. In a liquid lens, a droplet of water takes the place of the glass in a standard lens. As the electrical field around the water droplet changes, the droplet changes its shape and therefore changes the focus of the lens. This allows the device to take thousands of pictures focused at different depths below the skin's surface. Combining these images creates a fully in-focus image of all of the tissue up to 1 millimeter deep in human skin, which includes important skin tissue structures. Because the device uses near infrared light instead of ultrasounds, the images have a precise, micron-scale resolution instead of a millimeter-scale resolution.

The process has been successfully tested in in-vivo human skin and several papers on it have been published in peer-reviewed journals. Rolland says that the next step is to start using it in a clinical research environment so its ability to discriminate between different types of lesions may be assessed.

Rolland joined the faculty of the Hajim School of Engineering and Applied Science's Institute of Optics in 2009. She is the Brian J. Thompson Professor of Optical Engineering and is also a professor of biomedical engineering and associate director of the R.E. Hopkins Center for Optical Design and Engineering.

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Augmented Reality System for Learning Chess

An ordinary webcam, a chess board, a set of 32 pieces and custom software are the key elements in the final degree project of the telecommunications engineering students Ivan Paquico and Cristina Palmero, from the UPC-Barcelona Tech's Terrassa School of Engineering (EET). The project, for which the students were awarded a distinction, was directed by the professor Jordi Voltas and completed during an international mobility placement in Finland.

The system created by Ivan Paquico, the 2001 Spanish Internet chess champion, and Cristina Palmero, a keen player and federation member, is a didactic tool that will help chess clubs and associations to teach the game and make it more appealing, particularly to younger players.

The system combines augmented reality, computer vision and artificial intelligence, and the only equipment required is a high-definition home webcam, the Augmented Reality Chess software, a standard board and pieces, and a set of cardboard markers the same size as the squares on the board, each marked with the first letter of the corresponding piece: R for the king (reiin Catalan), D for the queen (dama), T for the rooks (torres), A for the bishops (alfils), C for the knights (cavalls) and P for the pawns (peons).

Learning chess with virtual pieces

To use the system, learners play with an ordinary chess board but move the cardboard markers instead of standard pieces. The table is lit from above and the webcam focuses on the board, and every time the player moves one of the markers the system recognises the piece and reproduces the move in 3D on the computer screen, creating a virtual representation of the game.

For example, if the learner moves the marker P (pawn), the corresponding piece will be displayed on the screen in 3D, with all of the possible moves indicated. This is a simple and attractive way of showing novices the permitted movements of each piece, making the system particularly suitable for children learning the basics of this board game.

Making chess accessible to all

The learning tool also incorporates a move-tracking program called Chess Recognition: from the images captured by the webcam, the system instantly recognises and analyses every movement of every piece and can act as a referee, identify illegal moves and provide the players with an audible description of the game status. According to Ivan Paquico and Cristina Palmero, this feature could be very useful for players with visual impairment -- who have their own federation and, until now, have had to play with specially adapted boards and pieces -- and for clubs and federations, tournament organisers and enthusiasts of all levels.

The Chess Recognition program saves whole games so that they can be shared, broadcast online and viewed on demand, and can generate a complete user history for analysing the evolution of a player's game. The program also creates an automatic copy of the scoresheet (the official record of each game) for players to view or print.

The technology for playing chess and recording games online has been available for a number of years, but until now players needed sophisticated equipment including pieces with integrated chips and a special electronic board with a USB connection. The standard retail cost of this equipment is between 400 and 500 euros.

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New Wireless Technology Developed for Faster, More Efficient Networks

"Wireless communication is a one-way street. Over."

Radio traffic can flow in only one direction at a time on a specific frequency, hence the frequent use of"over" by pilots and air traffic controllers, walkie-talkie users and emergency personnel as they take turns speaking.

But now, Stanford researchers have developed the first wireless radios that can send and receive signals at the same time.

This immediately makes them twice as fast as existing technology, and with further tweaking will likely lead to even faster and more efficient networks in the future.

"Textbooks say you can't do it," said Philip Levis, assistant professor of computer science and of electrical engineering."The new system completely reworks our assumptions about how wireless networks can be designed," he said.

Cell phone networks allow users to talk and listen simultaneously, but they use a work-around that is expensive and requires careful planning, making the technique less feasible for other wireless networks, including Wi-Fi.

Sparked from a simple idea

A trio of electrical engineering graduate students, Jung Il Choi, Mayank Jain and Kannan Srinivasan, began working on a new approach when they came up with a seemingly simple idea. What if radios could do the same thing our brains do when we listen and talk simultaneously: screen out the sound of our own voice?

In most wireless networks, each device has to take turns speaking or listening."It's like two people shouting messages to each other at the same time," said Levis."If both people are shouting at the same time, neither of them will hear the other."

It took the students several months to figure out how to build the new radio, with help from Levis and Sachin Katti, assistant professor of computer science and of electrical engineering.

Their main roadblock to two-way simultaneous conversation was this: Incoming signals are overwhelmed by the radio's own transmissions, making it impossible to talk and listen at the same time.

"When a radio is transmitting, its own transmission is millions, billions of times stronger than anything else it might hear {from another radio}," Levis said."It's trying to hear a whisper while you yourself are shouting."

But, the researchers realized, if a radio receiver could filter out the signal from its own transmitter, weak incoming signals could be heard."You can make it so you don't hear your own shout and you can hear someone else's whisper," Levis said.

Their setup takes advantage of the fact that each radio knows exactly what it's transmitting, and hence what its receiver should filter out. The process is analogous to noise-canceling headphones.

When the researchers demonstrated their device last fall at MobiCom 2010, an international gathering of more than 500 of the world's top experts in mobile networking, they won the prize for best demonstration. Until then, people didn't believe sending and receiving signals simultaneously could be done, Jain said. Levis said a researcher even told the students their idea was"so simple and effective, it won't work," because something that obvious must have already been tried unsuccessfully.

Breakthrough for communications technology

But work it did, with major implications for future communications networks. The most obvious effect of sending and receiving signals simultaneously is that it instantly doubles the amount of information you can send, Levis said. That means much-improved home and office networks that are faster and less congested.

But Levis also sees the technology having larger impacts, such as overcoming a major problem with air traffic control communications. With current systems, if two aircraft try to call the control tower at the same time on the same frequency, neither will get through. Levis says these blocked transmissions have caused aircraft collisions, which the new system would help prevent.

The group has a provisional patent on the technology and is working to commercialize it. They are currently trying to increase both the strength of the transmissions and the distances over which they work. These improvements are necessary before the technology is practical for use in Wi-Fi networks.

But even more promising are the system's implications for future networks. Once hardware and software are built to take advantage of simultaneous two-way transmission,"there's no predicting the scope of the results," Levis said.

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Toward an Optical Atomic Clock: Physicists Develop Atomic Frequency Standard for One of World’s Most Precise Clocks

The construction of a Polish optical atomic clock, a device of precision rarely matched in the world, will soon enter its final phase. A group led by Prof. Wojciech Gawlik at the Department of Photonics, Institute of Physics, Jagiellonian University has just constructed the last of the key components required for the construction of the clock: an atomic standard based on cold strontium atoms. After the conclusion of a series of tests, the device will be transported to the National Laboratory for Atomic, Molecular and Optical Physics (KL FAMO) in Toruń, where physicists will combine it with the two remaining components: an optical comb developed by a group led by Prof. Czesław Radzewicz from the University of Warsaw (UW) and an ultra-precise laser built under the supervision of Roman Ciuryłło, PhD, at the Nicolaus Copernicus University (UMK).

Precise time measurements are of key importance to the effective functioning of our civilization. Without them, modern telecommunication and navigation systems, particularly satellite systems, would cease to function. Ultra-precise clocks are also indispensable for research on the fundamental properties of reality, among others, for investigating whether the values of physical constants are truly constant and investigating the extent to which the general theory of relativity provides an accurate description of the Universe.

The Polish optical atomic clock construction project, financed solely by the Ministry of Science and Higher Education, was started two years ago and is conducted by groups of physicists from all over Poland, currently collaborating within the framework of KL FAMO which is a part of the National Laboratory for Quantum Technologies. The theoretical precision of time measurements of the clock under construction will be two orders of magnitude greater than that of the most precise cesium clocks, which are currently used, among others, to define the standard second."The Polish clock will have an accuracy of one second in a few dozen billion years, which is a period several times longer than that which elapsed from the Big Bang. Such precise timekeeping devices can nowadays be found only in a handful of research centres in the world," says Prof. Wojciech Gawlik, head of the team of physicists from Cracow.

All clocks make use of a certain frequency standard, a periodic physical phenomenon. In the case of a wristwatch, the standard is a quartz resonator with an oscillating quartz crystal. Commonly used atomic clocks make use of an electronic transition between energy levels in cesium atoms. The physicists from Cracow, on the other hand, have constructed a standard based on strontium atoms, in which electronic transitions between atomic energy levels require absorption and emission of electromagnetic radiation of a much higher frequency than in cesium. The frequency lies in the optical range (hence the adjective"optical" in the name of the clock). Confined in a laser trap, strontium atoms are isolated from the surroundings and cooled with a laser to an extremely low temperature of the order of microkelvins. Under these conditions, the probability of atomic collisions is low, which greatly reduces the possibility of disturbance. The new standard is currently undergoing the first tests.

The frequency standard based on strontium atoms is one of the components of the optical atomic clock. It will be used to stabilize the frequency of the ultra-precise laser built in Toruń. It is precisely the vibrations of the electric field of a light beam emitted by the laser that will be counted as elementary units of time, recurring with great precision. Yet the laser operates with such a high frequency that counting the individual oscillations is beyond the capabilities of electronic systems. What is needed is a device which acts as a toothed gear. The device in question is a frequency comb -- a set of numerous light waves of narrow, equidistant frequencies. The comb, generated by a laser emitting ultra-short light pulses, allows for a synchronic and error-free transfer of atomic standard oscillations into radio wave frequency range -- radio waves can be electronically counted. The frequency comb has already been operated by scientists from the Ultrafast Phenomena Laboratory of the Institute of Experimental Physics, University of Warsaw and preliminarily combined with a commercial reference laser of a stabilized frequency of light. Works are currently underway to combine it with the ultra-precise laser built at the National Laboratory FAMO in Toruń.

"Our atomic standard based on strontium atoms is the third, final piece of the puzzle. In several months' time, after the tests and after transporting it to Toruń, we will be able to start putting the clock together," observes Prof. Gawlik.

The National Laboratory for Quantum Technologies (nltk.fuw.edu.pl) is a consortium of leading Polish scientific institutions conducting research in the field of quantum technologies, including quantum computing, quantum engineering and related fields. The NLTK consists of: the University of Warsaw, the Wrocław University of Technology, the Institute of Physics of the Polish Academy of Sciences, the Nicolaus Copernicus University in Toruń, the Jagiellonian University, the University of Gdańsk, the University ofŁódź, and the Center for Theoretical Physics of the Polish Academy of Sciences. A project of the same name is carried out in five of the eight institutions of the NLTK consortium. The aim of the project is to create and equip the member scientific institutions with equipment necessary for conducting world-class joint scientific research as well as research and development. The National Laboratory for Quantum Technologies Project is co-financed by the European Regional Development Fund under the Operational Programme Innovative Economy 2007-2013, Priority 2, Infrastructure of the R&D sphere, Action 2.2"Support for the creation of joint research infrastructure of scientific institutions."

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Next-Generation Electronic Devices: Conduction, Surface States in Topological Insulator Nanoribbons Controlled

Perhaps most importantly, the surfaces of topological insulators enable the transport of spin-polarized electrons while preventing the"scattering" typically associated with power consumption, in which electrons deviate from their trajectory, resulting in dissipation.

Because of such characteristics, these materials hold great potential for use in future transistors, memory devices and magnetic sensors that are highly energy efficient and require less power.

In a study published Feb. 13 inNature Nanotechnology, researchers from UCLA's Henry Samueli School of Engineering and Applied Science and from the materials division of Australia's University of Queensland show the promise of surface-conduction channels in topological insulator nanoribbons made of bismuth telluride and demonstrate that surface states in these nanoribbons are"tunable" -- able to be turned on and off depending on the position of the Fermi level.

"Our finding enables a variety of opportunities in building potential new-generation, low-dissipation nanoelectronic and spintronic devices, from magnetic sensing to storage," said Kang L. Wang, the Raytheon Professor of Electrical Engineering at UCLA Engineering, whose team carried out the research.

Bismuth telluride is well known as a thermoelectric material and has also been predicted to be a three-dimensional topological insulator with robust and unique surface states. Recent experiments with bismuth telluride bulk materials have also suggested two-dimensional conduction channels originating from the surface states. But it has been a great challenge to modify surface conduction, because of dominant bulk contribution due to impurities and thermal excitations in such small-band-gap semiconductors.

The development of topological insulator nanoribbons has helped. With their large surface-to-volume ratios, these nanoribbons significantly enhance surface conditions and enable surface manipulation by external means.

Wang and his team used thin bismuth telluride nanoribbons as conducting channels in field-effect transistor structures. These rely on an electric field to control the Fermi level and hence the conductivity of a channel. The researchers were able to demonstrate for the first time the possibility of controlling surface states in topological insulator nanostructures.

"We have demonstrated a clear surface conduction by partially removing the bulk conduction using an external electric field," said Faxian Xiu, a UCLA staff research associate and lead author of the study."By properly tuning the gate voltage, very high surface conduction was achieved, up to 51 percent, which represents the highest values in topological insulators."

"This research is very exciting because of the possibility to build nanodevices with a novel operating principle," said Wang, who is also associate director of the California NanoSystems Institute (CNSI) at UCLA."Very similar to the development of graphene, the topological insulators could be made into high-speed transistors and ultra-high-sensitivity sensors."

The new findings shed light on the controllability of the surface spin states in topological insulator nanoribbons and demonstrate significant progress toward high surface electric conditions for practical device applications. The next step for Wang's team is to produce high-speed devices based on their discovery.

"The ideal scenario is to achieve 100 percent surface conduction with a complete insulating state in the bulk," Xiu said."Based on the current work, we are targeting high-performance transistors with power consumption that is much less than the conventional complementary metal-oxide semiconductors (CMOS) technology used typically in today's electronics."

Study collaborators Jin Zou, a professor of materials engineering at the University of Queensland; Yong Wang, a Queensland International Fellow; and Zou's team at the division of materials at the University of Queensland contributed significantly to this work. A portion of the research was also done in Alexandros Shailos' lab at UCLA.

The study was funded by the Focus Center Research Program -- Center on Functional Engineered Nano Architectonics (FENA) at UCLA Engineering; the U.S. Defense Advanced Research Projects Agency (DARPA); and the Australian Research Council. The research on topological insulators was pioneered by FENA's Shoucheng Zhang, a professor of physics at Stanford University.

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Getting Cars Onto the Road Faster

The auto industry faces major challenges. New models are entering the market at ever shorter intervals, products are becoming more complex, and the trend towards electric cars requires modified vehicle structures. European production sites are coming under increasing cost pressure from low-wage countries. Cost reductions, shorter production times, new materials and innovative assembly techniques are needed if companies are to remain competitive. To achieve these goals, 23 business and research organizations are participating in the EU's Pegasus project (www.pegasus-eu.net). One of the research partners is the Fraunhofer Institute for Chemical Technology ICT in Pfinztal, which is contributing its expertise in the polymer engineering sector. The project partners have jointly developed a software platform to reduce development times and costs.

The Integrated Design and Engineering Environment (IDEE) is a CAD/CAE/CAM software system which is connected to an intelligent database. It analyzes the functional requirements of a product and identifies appropriate materials at an early stage of the development process. If, for example, a car roof is to be made in a different material than before, it is not necessary to conduct a new development process. Instead, the design engineers enter the component data into the software system, which assesses the information and then selects suitable materials and manufacturing processes. The platform also provides engineering guidelines for designing the tools that will be used to produce the component. The project partners have demonstrated how this platform could work on the example of a fender with integrated LED tail light."We used the original fender from a Smart. Our project demonstrates how this complex component can be produced more quickly and cheaply with new processing techniques, materials, bonding agents and tools," says Timo Huber, a scientist at Fraunhofer ICT. Instead of conventional lamps, the project partners fitted LED tail lights to the fender. This reduced the number of separate parts from eight to five, and the number of processing steps from twelve to five. Material and cost savings were also achieved by using conductor paths made of electrically conductive polymer. The conductive carbon nanotubes conduct the electricity from the connector to the LEDs and render metallic conductor structures superfluous.

A further example application: So that components such as the LED tail lights can be dismantled more quickly, they are bonded using a special adhesive. For this the research scientists at Fraunhofer ICT and their project partners developed a new microwave-active adhesive bonding system. When irradiated with microwaves the individual components lose their adhesion and can be easily taken apart. This means that parts can be efficiently recycled into different categories."In addition, we dyed the fender using newly developed pigments based on special nanoparticles," states Huber. These nanostructures can be worked in particularly evenly, to dye plastics such as polypropylene. This means fewer pigments are needed than usual."We have also taken the importance of protecting the climate into account. Further developments in local fiber reinforcement of structural vehicle components will reduce weight and therefore emissions of CO2," the scientist adds, and sums up:"All in all the IDEE system will shorten development times, cut the number of assembly steps and reduce the amount of material consumed." IDEE is still under development, but it can already be used to produce simple components. The software should be ready and available to the auto industry in about a year's time.

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Engineers Grow Nanolasers on Silicon, Pave Way for on-Chip Photonics

They describe their work in a paper to be published Feb. 6 in an advanced online issue of the journalNature Photonics.

"Our results impact a broad spectrum of scientific fields, including materials science, transistor technology, laser science, optoelectronics and optical physics," said the study's principal investigator, Connie Chang-Hasnain, UC Berkeley professor of electrical engineering and computer sciences.

The increasing performance demands of electronics have sent researchers in search of better ways to harness the inherent ability of light particles to carry far more data than electrical signals can. Optical interconnects are seen as a solution to overcoming the communications bottleneck within and between computer chips.

Because silicon, the material that forms the foundation of modern electronics, is extremely deficient at generating light, engineers have turned to another class of materials known as III-V (pronounced"three-five") semiconductors to create light-based components such as light-emitting diodes (LEDs) and lasers.

But the researchers pointed out that marrying III-V with silicon to create a single optoelectronic chip has been problematic. For one, the atomic structures of the two materials are mismatched.

"Growing III-V semiconductor films on silicon is like forcing two incongruent puzzle pieces together," said study lead author Roger Chen, a UC Berkeley graduate student in electrical engineering and computer sciences."It can be done, but the material gets damaged in the process."

Moreover, the manufacturing industry is set up for the production of silicon-based materials, so for practical reasons, the goal has been to integrate the fabrication of III-V devices into the existing infrastructure, the researchers said.

"Today's massive silicon electronics infrastructure is extremely difficult to change for both economic and technological reasons, so compatibility with silicon fabrication is critical," said Chang-Hasnain."One problem is that growth of III-V semiconductors has traditionally involved high temperatures -- 700 degrees Celsius or more -- that would destroy the electronics. Meanwhile, other integration approaches have not been scalable."

The UC Berkeley researchers overcame this limitation by finding a way to grow nanopillars made of indium gallium arsenide, a III-V material, onto a silicon surface at the relatively cool temperature of 400 degrees Celsius.

"Working at nanoscale levels has enabled us to grow high quality III-V materials at low temperatures such that silicon electronics can retain their functionality," said Chen.

The researchers used metal-organic chemical vapor deposition to grow the nanopillars on the silicon."This technique is potentially mass manufacturable, since such a system is already used commercially to make thin film solar cells and light emitting diodes," said Chang-Hasnain.

Once the nanopillar was made, the researchers showed that it could generate near infrared laser light -- a wavelength of about 950 nanometers -- at room temperature. The hexagonal geometry dictated by the crystal structure of the nanopillars creates a new, efficient, light-trapping optical cavity. Light circulates up and down the structure in a helical fashion and amplifies via this optical feedback mechanism.

The unique approach of growing nanolasers directly onto silicon could lead to highly efficient silicon photonics, the researchers said. They noted that the miniscule dimensions of the nanopillars -- smaller than one wavelength on each side, in some cases -- make it possible to pack them into small spaces with the added benefit of consuming very little energy

"Ultimately, this technique may provide a powerful and new avenue for engineering on-chip nanophotonic devices such as lasers, photodetectors, modulators and solar cells," said Chen.

"This is the first bottom-up integration of III-V nanolasers onto silicon chips using a growth process compatible with the CMOS (complementary metal oxide semiconductor) technology now used to make integrated circuits," said Chang-Hasnain."This research has the potential to catalyze an optoelectronics revolution in computing, communications, displays and optical signal processing. In the future, we expect to improve the characteristics of these lasers and ultimately control them electronically for a powerful marriage between photonic and electronic devices."

The Defense Advanced Research Projects Agency and a Department of Defense National Security Science and Engineering Faculty Fellowship helped support this research.

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Roaches Inspire Robotics: Researchers Use Common Cockroach to Fine-Tune Robots of the Future

Prof. Amir Ayali of Tel Aviv University's Department of Zoology says the study of cockroaches has already inspired advanced robotics. Robots have long been based on these six-legged houseguests, whose nervous system is relatively straightforward and easy to study. But until now, walking machines based on the cockroach's movement have been influenced by outside observations and mainly imitate the insect's appearance, not its internal mechanics.

He and his fellow researchers are delving deeper into the neurological functioning of the cockroach. This, he says, will give engineers the information they need to design robots with a more compact build and greater efficiency in terms of energy, time, robustness and rigidity. Such superior robotics can be even used to explore new terrain in outer space.

This research was recently presented at the International Neuroethology conference in Spain as well as the Israeli Neuroscience Meeting in December.

Roach control systems as the ideal model

According to Prof. Ayali, it's clear why robotics have been inspired by these unsavory insects. A cockroach is supported by at least three legs at all times during movement, which provides great stability."Not only do cockroaches arguably exhibit one of the most stable ways to walk, called a tripod gate," he explains,"but they move equally quickly on every kind of terrain. Their speed and stability is almost too good to be true."

In their lab, Prof. Ayali and his fellow researchers are conducting a number of tests to uncover the mysteries of the cockroach's nervous system, studying how sensory feedback from one leg is translated to the coordination of all the other legs. Their analysis of the contribution of each leg is shared with collaborating scientists at Princeton University, who use the information to construct models and simulations of insect locomotion.

Insects, says Prof. Ayali, utilize information from the environment around them to determine how they will move. Sensors give them data about the terrain they are encountering and how they should approach it. How this information transfers to the insect's legs is central to understanding how to mimic their locomotion.

An army of robotic insects

Cockroaches are not the only insects that have captured the scientific imagination. Projects that highlight both the flight of the locust and the crawling of the soft-bodied caterpillar are also underway.

Locusts are amazing flyers, Prof. Ayali notes. Scientists are studying both their aerodynamic build and their energy metabolism for long-distance flights. Recordings of their nervous systems and simultaneous video tracking to observe the movement of their wings during flight can be expected to lead to better technology for miniscule flying robots.

As for caterpillars, engineers are trying to recreate in soft-bodied robots what they call the creatures"endless degrees of freedom of movement.""Caterpillars are not confined by a stiff structure -- they have no rigid skeletons," says Prof. Ayali."This is exactly what makes them unique."

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Making a Point: Method Prints Nanostructures Using Hard, Sharp 'Pen' Tips Floating on Soft Polymer Springs

Hard-tip, soft-spring lithography (HSL) rolls into one method the best of scanning-probe lithography -- high resolution -- and the best of polymer pen lithography -- low cost and easy implementation.

HSL could be used in the areas of electronics (electronic circuits), medical diagnostics (gene chips and arrays of biomolecules) and pharmaceuticals (arrays for screening drug candidates), among others.

To demonstrate the method's capabilities, the researchers duplicated the pyramid on the U.S. one-dollar bill and the surrounding words approximately 19,000 times at 855 million dots per square inch. Each image consists of 6,982 dots. (They reproduced a bitmap representation of the pyramid, including the"Eye of Providence.") This exercise highlights the sub-50-nanometer resolution and the scalability of the method.

The results will be published Jan. 27 by the journalNature.

"Hard-tip, soft-spring lithography is to scanning-probe lithography what the disposable razor is to the razor industry," said Chad A. Mirkin, the paper's senior author."This is a major step forward in the realization of desktop fabrication that will allow researchers in academia and industry to create and study nanostructure prototypes on the fly."

Mirkin is the George B. Rathmann Professor of Chemistry in the Weinberg College of Arts and Sciences and professor of medicine, chemical and biological engineering, biomedical engineering and materials science and engineering and director of Northwestern's International Institute for Nanotechnology.

Micro- and nanolithographic techniques are used to create patterns and build surface architectures of materials on a small scale.

Scanning probe lithography, with its high resolution and registration accuracy, currently is a popular method for building nanostructures. The method is, however, difficult to scale up and produce multiple copies of a device or structure at low cost.

Scanning probe lithographies typically rely on the use of cantilevers as the printing device components. Cantilevers are microscopic levers with tips, typically used to deposit materials on surfaces in a printing experiment. They are fragile, expensive, cumbersome and difficult to implement in an array-based experiment.

"Scaling cantilever-based architectures at low cost is not trivial and often leads to devices that are difficult to operate and limited with respect to the scope of application," Mirkin said.

Hard-tip, soft-spring lithography uses a soft polymer backing that supports sharp silicon tips as its"print head." The spring polymer backing allows all of the tips to come in contact with the surface in a uniform manner and eliminates the need to use cantilevers. Essentially, hard tips are floating on soft polymeric springs, allowing either materials or energy to be delivered to a surface.

HSL offers a method that quickly and inexpensively produces patterns of high quality and with high resolution and density. The prototype arrays containing 4,750 tips can be fabricated for the cost of a single cantilever-based tip and made in mass, Mirkin said.

Mirkin and his team demonstrated an array of 4,750 ultra-sharp silicon tips aligned over an area of one square centimeter, with larger arrays possible. Patterns of features with sub-50-nanometer resolution can be made with feature size controlled by tip contact time with the substrate.

They produced patterns"writing" with molecules and showed that as the tips push against the substrate the flexible backing compresses, indicating the tips are in contact with the surface and writing is occurring. (The silicon tips do not deform under pressure.)

"Eventually we should be able to build arrays with millions of pens, where each pen is independently actuated," Mirkin said.

The researchers also demonstrated the ability to use hard-tip, soft-spring lithography to transfer mechanical and electrical energy to a surface.

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World's First Programmable Nanoprocessor: Nanowire Tiles Can Perform Arithmetic and Logical Functions

The groundbreaking prototype computer system, described in a paper appearing in the journalNature, represents a significant step forward in the complexity of computer circuits that can be assembled from synthesized nanometer-scale components.

It also represents an advance because these ultra-tiny nanocircuits can be programmed electronically to perform a number of basic arithmetic and logical functions.

"This work represents a quantum jump forward in the complexity and function of circuits built from the bottom up, and thus demonstrates that this bottom-up paradigm, which is distinct from the way commercial circuits are built today, can yield nanoprocessors and other integrated systems of the future," says principal investigator Charles M. Lieber, who holds a joint appointment at Harvard's Department of Chemistry and Chemical Biology and School of Engineering and Applied Sciences.

The work was enabled by advances in the design and synthesis of nanowire building blocks. These nanowire components now demonstrate the reproducibility needed to build functional electronic circuits, and also do so at a size and material complexity difficult to achieve by traditional top-down approaches.

Moreover, the tiled architecture is fully scalable, allowing the assembly of much larger and ever more functional nanoprocessors.

"For the past 10 to 15 years, researchers working with nanowires, carbon nanotubes, and other nanostructures have struggled to build all but the most basic circuits, in large part due to variations in properties of individual nanostructures," says Lieber, the Mark Hyman Professor of Chemistry."We have shown that this limitation can now be overcome and are excited about prospects of exploiting the bottom-up paradigm of biology in building future electronics."

An additional feature of the advance is that the circuits in the nanoprocessor operate using very little power, even allowing for their miniscule size, because their component nanowires contain transistor switches that are"nonvolatile."

This means that unlike transistors in conventional microcomputer circuits, once the nanowire transistors are programmed, they do not require any additional expenditure of electrical power for maintaining memory.

"Because of their very small size and very low power requirements, these new nanoprocessor circuits are building blocks that can control and enable an entirely new class of much smaller, lighter weight electronic sensors and consumer electronics," says co-author Shamik Das, the lead engineer in MITRE's Nanosystems Group.

"This new nanoprocessor represents a major milestone toward realizing the vision of a nanocomputer that was first articulated more than 50 years ago by physicist Richard Feynman," says James Ellenbogen, a chief scientist at MITRE.

Co-authors on the paper included four members of Lieber's lab at Harvard: Hao Yan (Ph.D. '10), SungWoo Nam (Ph.D. '10), Yongjie Hu (Ph.D. '10), and doctoral candidate Hwan Sung Choe, as well as collaborators at MITRE.

The research team at MITRE comprised Das, Ellenbogen, and nanotechnology laboratory director Jim Klemic. The MITRE Corporation is a not-for-profit company that provides systems engineering, research and development, and information technology support to the government. MITRE's principal locations are in Bedford, Mass., and McLean, Va.

The research was supported by a Department of Defense National Security Science and Engineering Faculty Fellowship, the National Nanotechnology Initiative, and the MITRE Innovation Program.

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Hydrogels Used to Make Precise New Sensor

The"diffraction-based" sensors are made of thin stripes of a gelatinous material called a hydrogel, which expands and contracts depending on the acidity of its environment.

Recent research findings have demonstrated that the sensor can be used to precisely determine pH -- a measure of how acidic or basic a liquid is -- revealing information about substances in liquid environments, said Cagri Savran (pronounced Chary Savran), an associate professor of mechanical engineering at Purdue University.

The sensor's simple design could make it more practical than other sensors in development, he said.

"Many sensors being developed today are brilliantly designed but are too expensive to produce, require highly skilled operators and are not robust enough to be practical," said Savran, whose work is based at Purdue's Birck Nanotechnology Center in the university's Discovery Park.

New findings show the technology is highly sensitive and might be used in chemical and biological applications including environmental monitoring in waterways and glucose monitoring in blood.

"As with any novel platform, more development is needed, but the detection principle behind this technology is so simple that it wouldn't be difficult to commercialize," said Savran, who is collaborating with another team of researchers led by Babak Ziaie, a Purdue professor of electrical and computer engineering and biomedical engineering.

Findings are detailed in a paper presented during the IEEE Sensors 2010 Conference in November and also published in the conference proceedings. The paper was written by postdoctoral researcher Chun-Li Chang, doctoral student Zhenwen Ding, Ziaie and Savran.

The flexible, water-insoluble hydrogel is formed into a series of raised stripes called a"diffraction grating," which is coated with gold on both the stripe surfaces and the spaces in between. The stripes expand and contract depending on the pH level of the environment.

Researchers in Ziaie's lab fabricated the hydrogel, while Savran's group led work in the design, development and testing of the diffraction-based sensor.

The sensors work by analyzing laser light reflecting off the gold coatings. Reflections from the stripes and spaces in between interfere with each other, creating a"diffraction pattern" that differs depending on the height of the stripes.

These diffraction patterns indicate minute changes in the movement of the hydrogel stripes in response to the environment, in effect measuring changes in pH.

"By precise measurement of pH, the diffraction patterns can reveal a lot of information about the sample environment," said Savran, who by courtesy is an associate professor of biomedical engineering and electrical and computer engineering."This technology detects very small changes in the swelling of the diffraction grating, which makes them very sensitive."

The pH of a liquid is recorded on a scale from 0 to 14, with 0 being the most acidic and 14 the most basic. Findings showed the device's high sensitivity enables it to resolve changes smaller than one-1,000th on the pH scale, measuring swelling of only a few nanometers. A nanometer is about 50,000 times smaller than the finest sand grain.

"We know we can make them even more sensitive," Savran said."By using different hydrogels, gratings responsive to stimuli other than pH can also be fabricated."

The work is ongoing.

"It's a good example of collaborations that can blossom when labs focusing on different research are located next to each other," Savran said."Professor Ziaie's lab was already working with hydrogels, and my group was working on diffraction-based sensors. Hearing about the hydrogels work next door, one of my postdoctoral researchers, Chun-Li Chang thought of making a reflective diffraction grating out of hydrogels."

The Office of Technology Commercialization of the Purdue Research Foundation has filed for U.S. patent protection on the concept.

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Fingerprint Makes Computer Chips Counterfeit-Proof

Fraunhofer researchers will be presenting a prototype at the embedded world Exhibition& Conference in Nuremberg from March 1 to 3.

Product piracy long ago ceased to be limited exclusively to the consumer goods sector. Industry, too, is increasingly having to combat this problem. Cheap fakes cost business dear: The German mechanical and plant engineering sector alone lost 6.4 billion euros of revenue in 2010, according to a survey by the German Engineering Federation (VDMA). Sales losses aside, low-quality counterfeits can also damage a company's brand image. Worse, they can even put people's lives at risk if they are used in areas where safety is paramount, such as automobile or aircraft manufacture. Patent rights or organizational provisions such as confidentiality agreements are no longer sufficient to prevent product piracy. Today's commercially available anti-piracy technology provides a degree of protection, but it no longer constitutes an insurmountable obstacle for the product counterfeiters: Criminals are using scanning electron microscopes, focused ion beams or laser bolts to intercept security keys -- and adopting increasingly sophisticated methods.

No two chips are the same

At embedded world, researchers from the Fraunhofer Institute for Secure Information Technology SIT will be demonstrating how electronic components or chips can be made counterfeit-proof using physical unclonable functions (PUFs)."Every component has a kind of individual fingerprint since small differences inevitably arise between components during production," explains Dominik Merli, a scientist at Fraunhofer SIT in Garching near Munich. Printed circuits, for instance, end up with minimal variations in thickness or length during the manufacturing process. While these variations do not affect functionality, they can be used to generate a unique code.

Invasive attacks destroy the structure

A PUF module is integrated directly into a chip -- a setup that is feasible not only in a large number of programmable semiconductors known as FPGAs (field programmable gate arrays) but equally in hardware components such as microchips and smartcards."At its heart is a measuring circuit, for instance a ring oscillator. This oscillator generates a characteristic clock signal which allows the chip's precise material properties to be determined. Special electronic circuits then read these measurement data and generate the component-specific key from the data," explains Merli. Unlike conventional cryptographic processes, the secret key is not stored on the hardware but is regenerated as and when required. Since the code relates directly to the system properties at any given point in time, it is virtually impossible to extract and clone it. Invasive attacks on the chip would alter physical parameters, thus distorting or destroying the unique structure.

The Garching-based researchers have already developed two prototypes: A butterfly PUF and a ring oscillator PUF. At present, these modules are being optimized for practical applications. The experts will be at embedded world in Nuremberg (hall 11, stand 203) from March 1-3 to showcase FPGA boards that can generate an individual cryptographic key using a ring oscillator PUF. These allow attack-resistant security solutions to be rolled out in embedded systems.

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Clay-Armored Bubbles May Have Formed First Protocells: Minerals Could Have Played a Key Role in the Origins of Life

The research, published online in the journalSoft Matter,shows that clay vesicles provide an ideal container for the compartmentalization of complex organic molecules.

The authors say the discovery opens the possibility that primitive cells might have formed inside inorganic clay microcompartments.

"A lot of work, dating back several decades, explores the role of air bubbles in concentrating molecules and nanoparticles to allow interesting chemistry to occur," says lead author Anand Bala Subramaniam, a doctoral candidate at SEAS.

"We have now provided a complete physical mechanism for the transition from a two-phase clay-air bubble system, which precludes any aqueous-phase chemistry, to a single aqueous-phase clay vesicle system," Subramaniam says,"creating a semipermeable vesicle from materials that are readily available in the environment."

"Clay-armored bubbles" form naturally when platelike particles of montmorillonite collect on the outer surface of air bubbles under water.

When the clay bubbles come into contact with simple organic liquids like ethanol and methanol, which have a lower surface tension than water, the liquid wets the overlapping plates. As the inner surface of the clay shell becomes wet, the disturbed air bubble inside dissolves.

The resulting clay vesicle is a strong, spherical shell that creates a physical boundary between the water inside and the water outside. The translucent, cell-like vesicles are robust enough to protect their contents in a dynamic, aquatic environment such as the ocean.

Microscopic pores in the vesicle walls create a semipermeable membrane that allows chemical building blocks to enter the"cell," while preventing larger structures from leaving.

Scientists have studied montmorillonite, an abundant clay, for hundreds of years, and the mineral is known to serve as a chemical catalyst, encouraging lipids to form membranes and single nucleotides to join into strands of RNA.

Because liposomes and RNA would have been essential precursors to primordial life, Subramaniam and his coauthors suggest that the pores in the clay vesicles could do double duty as both selective entry points and catalytic sites.

"The conclusion here is that small fatty acid molecules go in and self-assemble into larger structures, and then they can't come out," says principal investigator Howard A. Stone, the Dixon Professor in Mechanical and Aerospace Engineering at Princeton, and a former Harvard faculty member."If there is a benefit to being protected in a clay vesicle, this is a natural way to favor and select for molecules that can self-organize."

Future research will explore the physical interactions between the platelike clay particles, and between the liquids and the clay. The researchers are also interested to see whether these clay vesicles can, indeed, be found in the natural environment today.

"Whether clay vesicles could have played a significant role in the origins of life is of course unknown," says Subramaniam,"but the fact that they are so robust, along with the well-known catalytic properties of clay, suggests that they may have had some part to play."

Subramaniam and Stone's coauthors include Jiandi Wan, of Princeton University, and Arvind Gopinath, of Brandeis University.

The research was funded by the Harvard Materials Research Science and Engineering Center and supported by the Harvard Center for Brain Science Imaging Facility.

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How Safe Is Nano? Nanotoxicology: An Interdisciplinary Challenge

"Research into the safety of nanotechnology combines biology, chemistry, and physics with workplace hygiene, materials science, and engineering to create a truly interdisciplinary research field," explain Krug and Wick."There are several factors to take into account in the interaction of nano-objects with organisms," they add. The term nanotoxicology is fully justified."Nanoscale particles can enter into cells by other means of transport than larger particles."

Another critical feature is the large surface area of nano-objects relative to their volume. If a similar amount of substance is absorbed, an organism comes into contact with a significantly larger number of molecules with nanoparticles than with larger particles. Dose-effect relationships cannot therefore be assumed to be the same. Furthermore, chemical and physical effects that do not occur with larger particles may arise."Whether the larger or smaller particle is more toxic in any given case cannot be predicted," according to the authors."Clearly, the type of chemical compound involved and its conformation in a specific case can also not be ignored." Carbon in the form of diamond nanoparticles is harmless, whereas in the form of nanotubes -- depending on length and degree of aggregation -- it may cause health problems. It is also thus impossible to avoid considering each nanomaterial in turn.

For a risk assessment, it is also necessary to keep in mind what dosage would be considered realistic and that not every observed biological effect automatically equates to a health risk.

Krug and Wick indicate that a large amount of data about the biological effects of nanomaterials is available, but not all studies are reliable. Sometimes it is not possible to reproduce the specific material tested or the conditions."By pointing out methodological inadequacies and making concrete recommendations for avoiding them, we are hoping to contribute to a lasting improvement in the data," state Krug and Wick.

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GRIN Plasmonics: A Practical Path to Superfast Computing, Ultrapowerful Optical Microscopy and Invisibility Carpet-Cloaking Devices

Working with composites featuring a dielectric (non-conducting) material on a metal substrate, and"grey-scale" electron beam lithography, a standard method in the computer chip industry for patterning 3-D surface topographies, the researchers have fabricated highly efficient plasmonic versions of Luneburg and Eaton lenses. A Luneburg lens focuses light from all directions equally well, and an Eaton lens bends light 90 degrees from all incoming directions.

"This past year, we used computer simulations to demonstrate that with only moderate modifications of an isotropic dielectric material in a dielectric-metal composite, it would be possible to achieve practical transformation optics results," says Xiang Zhang, who led this research."Our GRIN plasmonics technique provides a practical way for routing light at very small scales and producing efficient functional plasmonic devices."

Zhang, a principal investigator with Berkeley Lab's Materials Sciences Division and director of UC Berkeley's Nano-scale Science and Engineering Center (SINAM), is the corresponding author of a paper in the journalNature Nanotechnology, describing this work titled,"Plasmonic Luneburg and Eaton Lenses." Co-authoring the paper were Thomas Zentgraf, Yongmin Liu, Maiken Mikkelsen and Jason Valentine.

GRIN plasmonics combines methodologies from transformation optics and plasmonics, two rising new fields of science that could revolutionize what we are able to do with light. In transformation optics, the physical space through which light travels is warped to control the light's trajectory, similar to the way in which outer space is warped by a massive object under Einstein's relativity theory. In plasmonics, light is confined in dimensions smaller than the wavelength of photons in free space, making it possible to match the different length-scales associated with photonics and electronics in a single nanoscale device.

"Applying transformation optics to plasmonics allows for precise control of strongly confined light waves in the context of two-dimensional optics," Zhang says."Our technique is analogous to the well-known GRIN optics technique, whereas previous plasmonic techniques were realized by discrete structuring of the metal surface in a metal-dielectric composite."

Like all plasmonic technologies, GRIN plasmonics starts with an electronic surface wave that rolls through the conduction electrons on a metal. Just as the energy in a wave of light is carried in a quantized particle-like unit called a photon, so, too, is plasmonic energy carried in a quasi-particle called a plasmon. Plasmons will interact with photons at the interface of a metal and dielectric to form yet another quasi-particle, a surface plasmon polariton (SPP).

The Luneburg and Eaton lenses fabricated by Zhang and his co-authors interacted with SPPs rather than photons. To make these lenses, the researchers worked with a thin dielectric film (a thermplastic called PMMA) on top of a gold surface. When applying grey-scale electron beam lithography, the researchers exposed the dielectric film to an electron beam that was varied in dosage (charge per unit area) as it moved across the film's surface. This resulted in highly controlled differences in film thickness across the length of the dielectric that altered the local propagation of SPPs. In turn, the"mode index," which determines how fast the SPPs will propagate, is altered so that the direction of the SPPs can be influenced.

"By adiabatically tailoring the topology of the dielectric layer adjacent to the metal surface, we're able to continuously modify the mode index of SPPs," says Zentgraf."As a result, we can manipulate the flow of SPPs with a greater degree of freedom in the context of two-dimensional optics."

Says Liu,"The practicality of working only with the purely dielectric material to transform SPPs is a big selling point for GRIN plasmonics. Controlling the physical properties of metals on the nanometer length-scale, which is the penetration depth of electromagnetic waves associated with SPPs extending below the metal surfaces, is beyond the reach of existing nanofabrication techniques."

Adds Zentgraf,"Our approach has the potential to achieve low-loss functional plasmonic elements with a standard fabrication technology that is fully compatible with active plasmonics."

In theNature Nanotechnologypaper, the researchers say that inefficiencies in plasmonic devices due to SPPs lost through scattering could be reduced even further by incorporating various SPP gain materials, such as fluorescent dye molecules, directly into the dielectric. This, they say, would lead to an increased propagation distance that is highly desired for optical and plasmonic devices. It should also enable the realization of two-dimensional plasmonic elements beyond the Luneburg and Eaton lenses.

Says Mikkelsen,"GRIN plasmonics can be immediately applied to the design and production of various plasmonic elements, such as waveguides and beam splitters, to improve the performance of integrated plasmonics. Currently we are working on more complex, transformational plasmonic devices, such as plasmonic collimators, single plasmonic elements with multiple functions, and plasmonic lenses with enhanced performance."

This research was supported by the U.S. Army Research Office and the National Science Foundation's Nano-scale Science and Engineering Center.

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Future Surgeons May Use Robotic Nurse, 'Gesture Recognition'

Both the hand-gesture recognition and robotic nurse innovations might help to reduce the length of surgeries and the potential for infection, said Juan Pablo Wachs, an assistant professor of industrial engineering at Purdue University.

The"vision-based hand gesture recognition" technology could have other applications, including the coordination of emergency response activities during disasters.

"It's a concept Tom Cruise demonstrated vividly in the film 'Minority Report,'" Wachs said.

Surgeons routinely need to review medical images and records during surgery, but stepping away from the operating table and touching a keyboard and mouse can delay the surgery and increase the risk of spreading infection-causing bacteria.

The new approach is a system that uses a camera and specialized algorithms to recognize hand gestures as commands to instruct a computer or robot.

At the same time, a robotic scrub nurse represents a potential new tool that might improve operating-room efficiency, Wachs said.

Findings from the research will be detailed in a paper appearing in the February issue of Communications of the ACM, the flagship publication of the Association for Computing Machinery. The paper was written by researchers at Purdue, the Naval Postgraduate School in Monterey, Calif., and Ben-Gurion University of the Negev, Israel.

Research into hand-gesture recognition began several years ago in work led by the Washington Hospital Center and Ben-Gurion University, where Wachs was a research fellow and doctoral student, respectively.

He is now working to extend the system's capabilities in research with Purdue's School of Veterinary Medicine and the Department of Speech, Language, and Hearing Sciences.

"One challenge will be to develop the proper shapes of hand poses and the proper hand trajectory movements to reflect and express certain medical functions," Wachs said."You want to use intuitive and natural gestures for the surgeon, to express medical image navigation activities, but you also need to consider cultural and physical differences between surgeons. They may have different preferences regarding what gestures they may want to use."

Other challenges include providing computers with the ability to understand the context in which gestures are made and to discriminate between intended gestures versus unintended gestures.

"Say the surgeon starts talking to another person in the operating room and makes conversational gestures," Wachs said."You don't want the robot handing the surgeon a hemostat."

A scrub nurse assists the surgeon and hands the proper surgical instruments to the doctor when needed.

"While it will be very difficult using a robot to achieve the same level of performance as an experienced nurse who has been working with the same surgeon for years, often scrub nurses have had very limited experience with a particular surgeon, maximizing the chances for misunderstandings, delays and sometimes mistakes in the operating room," Wachs said."In that case, a robotic scrub nurse could be better."

The Purdue researcher has developed a prototype robotic scrub nurse, in work with faculty in the university's School of Veterinary Medicine.

Researchers at other institutions developing robotic scrub nurses have focused on voice recognition. However, little work has been done in the area of gesture recognition, Wachs said.

"Another big difference between our focus and the others is that we are also working on prediction, to anticipate what images the surgeon will need to see next and what instruments will be needed," he said.

Wachs is developing advanced algorithms that isolate the hands and apply"anthropometry," or predicting the position of the hands based on knowledge of where the surgeon's head is. The tracking is achieved through a camera mounted over the screen used for visualization of images.

"Another contribution is that by tracking a surgical instrument inside the patient's body, we can predict the most likely area that the surgeon may want to inspect using the electronic image medical record, and therefore saving browsing time between the images," Wachs said."This is done using a different sensor mounted over the surgical lights."

The hand-gesture recognition system uses a new type of camera developed by Microsoft, called Kinect, which senses three-dimensional space. The camera is found in new consumer electronics games that can track a person's hands without the use of a wand.

"You just step into the operating room, and automatically your body is mapped in 3-D," he said.

Accuracy and gesture-recognition speed depend on advanced software algorithms.

"Even if you have the best camera, you have to know how to program the camera, how to use the images," Wachs said."Otherwise, the system will work very slowly."

The research paper defines a set of requirements, including recommendations that the system should:

• Use a small vocabulary of simple, easily recognizable gestures.
• Not require the user to wear special virtual reality gloves or certain types of clothing.
• Be as low-cost as possible.
• Be responsive and able to keep up with the speed of a surgeon's hand gestures.
• Let the user know whether it understands the hand gestures by providing feedback, perhaps just a simple"OK."
• Use gestures that are easy for surgeons to learn, remember and carry out with little physical exertion.
• Be highly accurate in recognizing hand gestures.
• Use intuitive gestures, such as two fingers held apart to mimic a pair of scissors.
• Be able to disregard unintended gestures by the surgeon, perhaps made in conversation with colleagues in the operating room.
• Be able to quickly configure itself to work properly in different operating rooms, under various lighting conditions and other criteria.

"Eventually we also want to integrate voice recognition, but the biggest challenges are in gesture recognition," Wachs said."Much is already known about voice recognition."

The work is funded by the U.S. Agency for Healthcare Research and Quality.

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An Ice-Bar Made from Pure Ice

Building structures from ice and snow is probably something everyone has tried in their youth. Today, using ice as a building material is also something which is being discussed by scientists. The research group supervised by Prof. Kollegger of the Institute of Structural Engineering is looking into ways of building large-scale, stable domes made of ice. Following a thorough preparatory and research phase, a new ice dome construction method is now being put to the test in Obergurgl -- a world first. This structure, showing more than 10 metres free span, is now home to a bar -- for as long as the temperatures are low enough.

Using ice as a building material has actually been done before: entire ice hotels have been built in e.g. Scandinavia."In most cases though the spans of the structures are small or the ice is not a load-bearing component and merely acts as cladding for the actual construction," explains Prof. Kollegger. The team of Vienna University of Technology has developed an ice dome which presents a stable and free-standing safe structure, and does not require additional support using other building materials. Theoretical calculations and several experiments have been carried out in this area over the past few years and, thanks to the latest technology, ice structures which are large and stable enough to actually be used as serviceable buildings can now be built.

Slow deformation process - like a glacier

First, a 20 cm-thick plate of ice is cut into 16 segments. These two-dimensional segments have then to be transformed into a three-dimensional structure. The University research team takes advantage of one property of ice, known as"creep behaviour." If pressure is applied to the ice, it can slowly change its shape without breaking. Glacial creep functions similarly."The segments of ice are placed on stacks of wood. Then, under the load of its own weight, the ice begins to change shape all by itself, resulting in a curved dome segment," explains Sonja Dallinger, research assistant at the Institute of Structural Engineering and on-site manager of the Obergurgl construction experiment.

The greatest challenge that had to be faced was the prevention of any breakage of the individually curved segments when assembling the dome. To solve this issue, a wooden tower was erected and the dome segments were held together by means of steel chains. The wooden tower could only be removed once all the segments had been positioned correctly and the ice dome stood on its own.

Austria's coolest bar

The ice dome was constructed in front of the spa area of the Hotel Alpina in Obergurgl and is presently being used as an ice bar. The drinks are definitely pretty cool -- and of course it's up to you whether or not to wear a cocktail dress!

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Metamaterials Approach Makes Better Satellite Antennas

"Existing horn antennas have adequate performance, but have undergone little change over several decades except for advances in more accurate modeling techniques," said Erik Lier, technical Fellow, Lockheed Martin Space Systems Co."Modifications enabled by metamaterials can either enhance performance, or they can lower the mass and thus lower the cost of putting the antenna in space."

Lighter antennas cost less to boost into space and more energy-efficient antennas can reduce the size of storage batteries and solar cells, which also reduces the mass.

Metamaterials derive their unusual properties from structure rather than composition and possess exotic properties not usually found in nature.

"Working with Penn State, we decided that the first year we were going focus on applications for radio frequency antennas, where we thought we had a reasonable chance to succeed," said Lier.

According to Douglas H. Werner, professor of electrical engineering, Penn State, this is one of the first practical implementations of electromagnetic metamaterials that makes a real world device better.

"These results also help lay to rest the widely held viewpoint that metamaterials are primarily an academic curiosity and, due to their narrow bandwidth and relatively high loss, will never find their way into real-world devices," the researchers report in the current issue ofNature Materials.

They specifically designed their electromagnetic metamaterials to avoid previous limitations of narrow bandwidth and high intrinsic material loss, which results in signal loss. Their aim was not to design theoretical metamaterial-enhanced antennas, but to build a working prototype.

"We have developed design optimization tools that can be employed to meet real device requirements," said Werner."We can optimize the metamaterial to get the best device performance by tailoring its properties across a desired bandwidth to meet the specific needs of the horn antenna."

The researchers wanted an antenna that could work over a broad band of frequencies -- at least an octave -- and improve upon existing antennas. An octave in the radio frequency spectrum is a stretch of bandwidth where the upper frequency is twice the lower frequency -- 3.5 to 7 gigahertz for example, which is wider than the standard C-band.

Horn antennas are part of communications satellites that relay television and radio signals, telephone calls and data around the world. Two commonly used microwave bands on satellites are C-band -- used for long-distance radio and telecommunications -- and Ku-band -- used for broadcast television and remote television uplinks.

The researchers, who also included Qi Wu and Jeremy A. Bossard, postdoctoral fellows in electrical engineering, and Clinton P. Scarborough, graduate student, electrical engineering, all from Penn State, designed horn antenna liners from metamaterials with special low-index electromagnetic properties -- effective refractive index between zero and one -- which do not physically exist in natural materials. To increase bandwidth and decrease loss, the antenna liners needed to have repetitive structure considerably smaller than the wavelengths the antenna is designed to transmit.

Ku-band -- 12 to 18 gigahertz -- antennas require small structural intervals that are easily fabricated using conventional printed circuit board manufacturing techniques, while super extended C-band -- 3.4 to 6.725 gigahertz -- could be achieved with a simple wire grid structure that is easily manufactured with an interval of about a quarter of an inch between wires. The researchers chose to convert the C-band application into a prototype.

"This is just an example of what we can do," said Lier."It opens up the way for a broader range of other applications and is proof of the new metamaterial technology and an example of how it can be used."

The Lockheed Martin University Research Initiative program funded this project.

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