Students Create Portable Device To Detect Suicide Bombers

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ScienceDaily (July 2, 2009) — Improvised explosive devices (IEDs), the weapons of suicide bombers, are a major cause of soldier casualties in Iraq and Afghanistan. A group of University of Michigan engineering undergraduate students has developed a new way to detect them.

The students invented portable, palm-sized metal detectors that could be hidden in trash cans, under tables or in flower pots, for example. The detectors are designed to be part of a wireless sensor network that conveys to a base station where suspicious objects are located and who might be carrying them. Compared with existing technology, the sensors are cheaper, lower-power and longer-range. Each of the sensors weighs about 2 pounds.
"Their invention outperforms everything that exists in the market today," said Nilton Renno, a professor in the U-M Department of Atmospheric, Oceanic and Space Sciences. The students undertook this project in Renno's Engineering 450 senior level design class.
"They clearly have an excellent understanding of the problem. They also thought strategically and designed and optimized their solution. The combination of a movable command center with a wireless sensor network can be easily deployed in the field and adapted to different situations."
The core technology is based on a magnetometer, or metal detector, explained Ashwin Lalendran, an engineering student who worked on the project and graduated in May.
"We built it entirely in-house—the hardware and the software," Lalendran said. "Our sensors are small, flexible to deploy, inexpensive and scalable. It's extremely novel technology."
The U-M students recently won an Air Force-sponsored competition with Ohio State University. The U.S. Air Force Research Laboratory at Wright Patterson Air Force Base sponsored the project as well as the contest. Air Force research labs across the country sponsor similar contests on a regular basis to provide rapid reaction and innovative solutions to the Department of Defense's urgent needs, says Capt. Nate Terning, AFRL rapid reaction projects director.
The teams from U-M and Ohio State demonstrated their inventions June 2-3 in Dayton, Ohio at a mock large tailgate event where simulated IEDs and the students' technologies were hidden among the crowd. The students' technology was tasked with finding IEDs in the purses, backpacks or other packages of the tailgaters, without the tailgaters' knowledge. Michigan's invention found more IEDs than Ohio State's.
"We had an excellent turnout in technology," Terning said. "Regardless of the competition results, often successful ideas from each student team can be combined into a product which is then realized for DoD use in the future."
The students will continue to work on this project through the summer. Other students involved are: Steve Boland, a senior atmospheric, oceanic and space sciences major; Andry Supian a mechanical engineering major who graduated in April; Brian Hale, a senior aerospace engineering major; Kevin Huang, a junior computer science major; Michael Shin, a junior computer engineering major; and Vitaly Shatkovsky, a mechanical engineering major who graduated in April.
"I am very proud of the team for applying a sound engineering approach and a lot of imagination to the solution of an extremely difficult real-world problem. They worked well together and never gave up when the going got rough," said Bruce Block, an engineer in the Space Physics Research Laboratory who worked with the students.
Other Space Physics Research Lab engineers who assisted are Steve Musko and Steve Rogacki.
Adapted from materials provided by University of Michigan.

Optical Computer Closer: Optical Transistor Made From Single Molecule

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ScienceDaily (July 2, 2009) — ETH Zurich researchers have successfully created an optical transistor from a single molecule. This has brought them one step closer to an optical computer.

Internet connections and computers need to be ever faster and more powerful nowadays. However, conventional central processing units (CPUs) limit the performance of computers, for example because they produce an enormous amount of heat. The millions of transistors that switch and amplify the electronic signals in the CPUs are responsible for this. One square centimeter of CPU can emit up to 125 watts of heat, which is more than ten times as much as a square centimeter of an electric hotplate.
Photons instead of electrons
This is why scientists have been trying for some time to find ways to produce integrated circuits that operate on the basis of photons instead of electrons. The reason is that photons do not only generate much less heat than electrons, but they also enable considerably higher data transfer rates.
Although a large part of telecommunications engineering nowadays is based on optical signal transmission, the necessary encoding of the information is generated using electronically controlled switches. A compact optical transistor is still a long way off. Vahid Sandoghdar, Professor at the Laboratory of Physical Chemistry of ETH Zurich, explains that, “Comparing the current state of this technology with that of electronics, we are somewhat closer to the vacuum tube amplifiers that were around in the fifties than we are to today’s integrated circuits.”
However, his research group has now achieved a decisive breakthrough by successfully creating an optical transistor with a single molecule. For this, they have made use of the fact that a molecule’s energy is quantized: when laser light strikes a molecule that is in its ground state, the light is absorbed. As a result, the laser beam is quenched. Conversely, it is possible to release the absorbed energy again in a targeted way with a second light beam. This occurs because the beam changes the molecule’s quantum state, with the result that the light beam is amplified. This so-called stimulated emission, which Albert Einstein described over 90 years ago, also forms the basis for the principle of the laser.
Focusing on a nano scale
Jaesuk Hwang, first author of the study and a scientific member of Sandoghdar’s nano-optics group, explains that, “Amplification in a conventional laser is achieved by an enormous number of molecules.” By focusing a laser beam on only a single tiny molecule, the ETH Zurich scientists have now been able to generate stimulated emission using just one molecule. They were helped in this by the fact that, at low temperatures, molecules seem to increase their apparent surface area for interaction with light . The researchers therefore needed to cool the molecule down to minus 272 degrees Celsius (minus 457.6 degrees Fahrenheit), i.e. one degree above absolute zero. In this case, the enlarged surface area corresponded approximately to the diameter of the focused laser beam.
Switching light with light
By using one laser beam to prepare the quantum state of a single molecule in a controlled fashion, scientists could significantly attenuate or amplify a second laser beam. This mode of operation is identical to that of a conventional transistor, in which electrical potential can be used to modulate a second signal.
Thus component parts such as the new single molecule transistor may also pave the way for a quantum computer. Sandoghdar says, “Many more years of research will still be needed before photons replace electrons in transistors. In the meantime, scientists will learn to manipulate and control quantum systems in a targeted way, moving them closer to the dream of a quantum computer.”
Journal reference:
J. Hwang, M. Pototschnig, R. Lettow, G. Zumofen, A. Renn, S. Götzinger, V. Sandoghda. A single-molecule opzical transistor. Nature, 460, 76-80 DOI: 10.1038/nature08134
Adapted from materials provided by ETH Zurich.

Inexpensive Thin Printable Batteries Developed

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ScienceDaily (July 2, 2009) — For a long time, batteries were bulky and heavy. Now, a new cutting-edge battery is revolutionizing the field. It is thinner than a millimeter, lighter than a gram, and can be produced cost-effectively through a printing process.

In the past, it was necessary to race to the bank for every money transfer and every bank statement. Today, bank transactions can be easily carried out at home. Now where is that piece of paper again with the TAN numbers? In the future you can spare yourself the search for the number. Simply touch your EC card and a small integrated display shows the TAN number to be used. Just type in the number and off you go. This is made possible by a printable battery that can be produced cost-effectively on a large scale.
It was developed by a research team led by Prof. Dr. Reinhard Baumann of the Fraunhofer Research Institution for Electronic Nano Systems ENAS in Chemnitz together with colleagues from TU Chemnitz and Menippos GmbH. “Our goal is to be able to mass produce the batteries at a price of single digit cent range each,” states Dr. Andreas Willert, group manager at ENAS.
The characteristics of the battery differ significantly from those of conventional batteries. The printable version weighs less than one gram on the scales, is not even one millimeter thick and can therefore be integrated into bank cards, for example. The battery contains no mercury and is in this respect environmentally friendly. Its voltage is 1.5 V, which lies within the normal range. By placing several batteries in a row, voltages of 3 V, 4.5 V and 6 V can also be achieved. The new type of battery is composed of different layers: a zinc anode and a manganese cathode, among others. Zinc and manganese react with one another and produce electricity. However, the anode and the cathode layer dissipate gradually during this chemical process. Therefore, the battery is suitable for applications which have a limited life span or a limited power requirement, for instance greeting cards.
The batteries are printed using a silk-screen printing method similar to that used for t-shirts and signs. A kind of rubber lip presses the printing paste through a screen onto the substrate. A template covers the areas that are not to be printed on. Through this process it is possible to apply comparatively large quantities of printing paste, and the individual layers are slightly thicker than a hair. The researchers have already produced the batteries on a laboratory scale. At the end of this year, the first products could possibly be finished.
Adapted from materials provided by Fraunhofer-Gesellschaft.

New Statistical Technique Improves Precision Of Nanotechnology Data

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ScienceDaily (June 30, 2009) — A new statistical analysis technique that identifies and removes systematic bias, noise and equipment-based artifacts from experimental data could lead to more precise and reliable measurement of nanomaterials and nanostructures likely to have future industrial applications.

Known as sequential profile adjustment by regression (SPAR), the technique could also reduce the amount of experimental data required to make conclusions, and help distinguish true nanoscale phenomena from experimental error. Beyond nanomaterials and nanostructures, the technique could also improve reliability and precision in nanoelectronics measurements – and in studies of certain larger-scale systems.
Accurate understanding of these properties is critical to the development of future high-volume industrial applications for nanomaterials and nanostructures because manufacturers will require consistency in their products.
"Our statistical model will be useful when the nanomaterials industry scales up from laboratory production because industrial users cannot afford to make a detailed study of every production run," said C. F. Jeff Wu, a professor in the Stewart School of Industrial and Systems Engineering at the Georgia Institute of Technology. "The significant experimental errors can be filtered out automatically, which means this could be used in a manufacturing environment."
Sponsored by the National Science Foundation, the research was reported June 25, 2009 in the early edition of the journal Proceedings of the National Academy of Sciences. The paper is believed to be the first to describe the use of statistical techniques for quantitative analysis of data from nanomechanical measurements.
Nanotechnology researchers have long been troubled by the difficulty of measuring nanoscale properties and separating signals from noise and data artifacts. Data artifacts can be caused by such issues as the slippage of structures being studied, surface irregularities and inaccurate placement of the atomic force microscope tip onto samples.
In measuring the effects of extremely small forces acting on extremely small structures, signals of interest may be only two or three times stronger than experimental noise. That can make it difficult to draw conclusions, and potentially masks other interesting effects.
"In the past, we have really not known the statistical reliability of the data at this size scale," said Zhong Lin Wang, a Regents' professor in Georgia Tech's School of Materials Science and Engineering. "At the nanoscale, small errors are amplified. This new technique applies statistical theory to identify and analyze the data received from nanomechanics so we can be more confident of how reliable it is."
In developing the new technique, the researchers studied a data set measuring the deformation of zinc oxide nanobelts, research undertaken to determine the material's elastic modulus. Theoretically, applying force to a nanobelt with the tip of an atomic force microscope should produce consistent linear deformation, but the experimental data didn't always show that.
In some cases, less force appeared to create more deformation, and the deformation curve was not symmetrical. Wang's research team attempted to apply simple data-correction techniques, but was not satisfied with the results.
"The measurements they had done simply didn't match what was expected with the theoretical model," explained Wu, who holds a Coca-Cola chair in engineering statistics. "The curves should have been symmetric. To address this issue, we developed a new modeling technique that uses the data itself to filter out the mismatch step-by-step using the regression technique."
Ideally, researchers would search out and correct the experimental causes of these data errors, but because they occur at such small size scales, that would be difficult, noted V. Roshan Joseph, an associate professor in the Georgia Tech School of Industrial and Systems Engineering.
"Physics-based models are based on several assumptions that can go wrong in reality," he said. "We could try to identify all the sources of error and correct them, but that is very time-consuming. Statistical techniques can more easily correct the errors, so this process is more geared toward industrial use."
Beyond correcting the errors, the improved precision of the statistical technique could reduce the effort required to produce reliable experimental data on the properties of nanostructures. "With half of the experimental efforts, you can get about the same standard deviation as following the earlier method without the corrections," Wu said. "This translates into fewer time-consuming experiments to confirm the properties."
For the future, the research team – which includes Xinwei Deng and Wenjie Mai in addition to those already mentioned – plans to analyze the properties of nanowires, which are critical to the operation of a family of nanoscale electric generators being developed by Wang's research team. Correcting for data errors in these structures will require development of a separate model using the same SPAR techniques, Wu said.
Ultimately, SPAR may lead researchers to new fundamental explanations of the nanoscale world.
"One of the key issues today in nanotechnology is whether the existing physical theories can still be applied to explain the phenomena we are seeing," said Wang, who is also director of Georgia Tech's Center for Nanostructure Characterization and Fabrication. "We have tried to answer the question of whether we are truly observing new phenomena, or whether our errors are so large that we cannot see that the theory still works."
Wang plans to use the SPAR technique on future work, and to analyze past research for potential new findings. "What may have seemed like noise could actually be an important signal," he said. "This technique provides a truly new tool for data mining and analysis in nanotechnology."
Adapted from materials provided by Georgia Institute of Technology.

Unexpectedly Long-range Effects In Advanced Magnetic Devices

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ScienceDaily (July 1, 2009) — A tiny grid pattern has led materials scientists at the National Institute of Standards and Technology (NIST) and the Institute of Solid State Physics in Russia to an unexpected finding—the surprisingly strong and long-range effects of certain electromagnetic nanostructures used in data storage.

Their recently reported findings may add new scientific challenges to the design and manufacture of future ultra-high density data storage devices.
The team was studying the behavior of nanoscale structures that sandwich thin layers of materials with differing magnetic properties. In the past few decades such structures have been the subjects of intense research because they can have unusual and valuable magnetic properties. The data read heads on modern high-density disk drives usually exploit a version of the giant magnetoresistance (GMR) effect, which uses such layered structures for extremely sensitive magnetic field detectors.
Arrays of nanoscale sandwiches of a similar type might be used in future data storage devices that would outdo even today's astonishingly capacious microdrives because in principle the structures could be made even smaller than the minimum practical size for the magnetic islands that record data on hard disk drives, according to NIST metallurgist Robert Shull.
The key trick is to cover a thin layer of a ferromagnetic material, in which the magnetic direction of electrons, or "spins," tend to order themselves in the same direction, with an antiferromagnetic layer in which the spins tend to orient in opposite directions. By itself, the ferromagnetic layer will tend to magnetize in the direction of an externally imposed magnetic field—and just as easily magnetize in the opposite direction if the external field is reversed. For reasons that are still debated, the presence of the antiferromagnetic layer changes this. It biases the ferromagnet in one preferred direction, essentially pinning its field in that orientation. In a magnetoresistance read head, for example, this pinned layer serves as a reference direction that the sensor uses in detecting changing field directions on the disk that it is "reading.".
Researchers have long understood this pinning effect to be a short-range phenomenon. The influence of the antiferromagnetic layer is felt only a few tens of nanometers down into the ferromagnetic layer—verticallly. But what about sideways? To find out, the NIST/ISSP team started with a thin ferromagnetic film covering a silicon wafer and then added on top a grid of antiferromagnetic strips about 10 nanometers thick and 10 micrometers wide, separated by gaps of about 100 micrometers. Using an instrument that provided real-time images of the magnetization within grid the structure, the team watched the grid structure as they increased and decreased the magnetic field surrounding it.
What they found surprised them.
As expected, the ferromagnetic material directly under the grid lines showed the pinning effect, but, quite unexpectedly, so did the uncovered material in regions between the grid lines far removed from the antiferromagnetic material. "This pinning effect extends for maybe tens of nanometers down into the ferromagnet right underneath," explains Shull, "so you might expect that there could be some residual effect maybe tens of nanometers away from it to the sides. But you wouldn't expect it to extend 10 micrometers away—that's 10 thousand nanometers." In fact, the effect extends to regions 50 micrometers away from the closest antiferromagnetic strip, at least 1,000 times further than was previously known to be possible.
The ramifications, says Shull, are that engineers planning to build dense arrays of these structures onto a chip for high-performance memory or sensor devices will find interesting new scientific issues for investigation in optimizing how closely they can be packed without interfering with each other.
Journal reference:
Kabanov et al. Unexpectedly long-range influence on thin-film magnetization reversal of a ferromagnet by a rectangular array of FeMn pinning films. Physical Review B, 2009; 79 (14): 144435 DOI: 10.1103/PhysRevB.79.144435
Adapted from materials provided by National Institute of Standards and Technology.

Quantum Communications One Step Closer: Novel Ion Trap For Sensing Force And Light Developed

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ScienceDaily (July 1, 2009) — Miniature devices for trapping ions (electrically charged atoms) are common components in atomic clocks and quantum computing research. Now, a novel ion trap geometry demonstrated at the National Institute of Standards and Technology (NIST) could usher in a new generation of applications because the device holds promise as a stylus for sensing very small forces or as an interface for efficient transfer of individual light particles for quantum communications.

The "stylus trap," built by physicists from NIST and Germany's University of Erlangen-Nuremberg, is described in Nature Physics. It uses fairly standard techniques to cool ions with laser light and trap them with electromagnetic fields. But whereas in conventional ion traps, the ions are surrounded by the trapping electrodes, in the stylus trap a single ion is captured above the tip of a set of steel electrodes, forming a point-like probe. The open trap geometry allows unprecedented access to the trapped ion, and the electrodes can be maneuvered close to surfaces. The researchers theoretically modeled and then built several different versions of the trap and characterized them using single magnesium ions.
The new trap, if used to measure forces with the ion as a stylus probe tip, is about one million times more sensitive than an atomic force microscope using a cantilever as a sensor because the ion is lighter in mass and reacts more strongly to small forces. In addition, ions offer combined sensitivity to both electric and magnetic fields or other force fields, producing a more versatile sensor than, for example, neutral atoms or quantum dots. By either scanning the ion trap near a surface or moving a sample near the trap, a user could map out the near-surface electric and magnetic fields. The ion is extremely sensitive to electric fields oscillating at between approximately 100 kilohertz and 10 megahertz.
The new trap also might be placed in the focus of a parabolic (cone-shaped) mirror so that light beams could be focused directly on the ion. Under the right conditions, single photons, particles of light, could be transferred between an optical fiber and the single ion with close to 95 percent efficiency. Efficient atom-fiber interfaces are crucial in long-distance quantum key cryptography (QKD), the best method known for protecting the privacy of a communications channel. In quantum computing research, fluorescent light emitted by ions could be collected with similar efficiency as a read-out signal. The new trap also could be used to compare heating rates of different electrode surfaces, a rapid approach to investigating a long-standing problem in the design of ion-trap quantum computers.
Research on the stylus trap was supported by the Intelligence Advanced Research Projects Activity.
Journal reference:
R. Maiwald, D. Leibfried, J. Britton, J.C. Bergquist, G. Leuchs, and D.J. Wineland. Stylus ion trap for enhanced access and sensing. Nature Physics, Online June 28
Adapted from materials provided by National Institute of Standards and Technology.

Researchers Unveil Whiskered Robot Rat

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ScienceDaily (June 30, 2009) — A team of scientists have developed an innovative robot rat which can seek out and identify objects using its whiskers. The SCRATCHbot robot will be demonstrated this week (1 July 2009) at an international workshop looking at how robots can help us examine the workings of the brain.

Researchers from the Bristol Robotics Lab, (a partnership between the University of the West of England and the University of Bristol) and the University of Sheffield have developed the SCRATCHbot, which is a significant milestone in the pan-european “ICEA” project to develop biologically-inspired artificial intelligence systems. As part of this project Professor Tony Prescott, from the University of Sheffield’s Department of Psychology, is working with the Bristol Robotics Lab to design innovative artificial touch technologies for robots that will also help us understand how the brain controls the movement of the sensory systems.
The new technology has been inspired by the use of touch in the animal kingdom. In nocturnal creatures, or those that inhabit poorly-lit places, this physical sense is widely preferred to vision as a primary means of discovering the world. Rats are especially effective at exploring their environments using their whiskers. They are able to accurately determine the position, shape and texture of objects using precise rhythmic sweeping movements of their whiskers, make rapid accurate decisions about objects, and then use the information to build environmental maps.
Robot designs often rely on vision to identify objects, but this new technology relies solely on sophisticated touch technology, enabling the robot to function in spaces such as dark or smoke-filled rooms, where vision cannot be used.
The new technology has the potential for a number of further applications from using robots underground, under the sea, or in extremely dusty conditions, where vision is often seriously compromised. The technology could also be used for tactile inspection of surfaces, such as materials in the textile industry, or closer to home in domestic products, for example vacuum cleaners that could sense textures for optimal cleaning.
Dr Tony Pipe, (BRL, UWE), says “For a long time, vision has been the biological sensory modality most studied by scientists. But active touch sensing is a key focus for those of us looking at biological systems which have implications for robotics research. Sensory systems such as rats’ whiskers have some particular advantages in this area. In humans, for example, where sensors are at the fingertips, they are more vulnerable to damage and injury than whiskers. Rats have the ability to operate with damaged whiskers and in theory broken whiskers on robots could be easily replaced, without affecting the whole robot and its expensive engineering.
“Future applications for this technology could include using robots underground, under the sea, or in extremely dusty conditions, where vision is often a seriously compromised sensory modality. Here, whisker technology could be used to sense objects and manoeuvre in a difficult environment. In a smoke filled room for example, a robot like this could help with a rescue operation by locating survivors of a fire. This research builds on previous work we have done on whisker sensing.”
Professor Prescott said: “Our project has reached a significant milestone in the development of actively-controlled, whisker-like sensors for intelligent machines. Although touch sensors are already employed in robots, the use of touch as a principal modality has been overlooked until now. By developing these biomimetic robots, we are not just designing novel touch-sensing devices, but also making a real contribution to understanding the biology of tactile sensing.”
Adapted from materials provided by University of the West of England.