Far Sighted Space Technology Finds Practical Uses on Earth

Ken Wood is presenting the project at the RAS National Astronomy Meeting in Llandudno, Wales.

The part of the Electromagnetic Spectrum including the far infra red and microwave is also called 'terahertz' radiation. Astronomers use this kind of radiation to study the Cosmic Microwave Background and the huge dust clouds where stars are born. The sensitive detectors they use will only operate at temperatures very close to absolute zero (minus 273C.) In Terahertz cameras like KIDCAM, those low temperatures are accessible in compact and less expensive ways using relatively new cooler technology. KIDCAM therefore has many potential day-to-day applications.

"We are all familiar with optical images of the surface of objects and X-ray images which penetrate through soft tissue to reveal bone structure. Terahertz observations give us something in between the two. For example, most clothing and packaging materials are transparent to Terahertz radiation, whereas skin, water, metal and a host of other interesting materials are not. This gives rise to some important day-to-day applications: detecting weapons concealed under clothing or inside parcels; distinguishing skin and breast cancer tissue; quality control of manufactures items and processes in factories. Our KIDCAM detectors are also very sensitive, and so we can look at the natural radiation emitted by the target. This means there are no safety issues like those associated with other imaging techniques which shine radiation, including X-rays, at the target," said Mr Wood.

Until recently, there have been many practical obstacles to using terahertz detectors. Terahertz sources have only become available to the non-specialist in the last 10 years and cooling the detectors to very low temperatures using liquid cryogens is costly and complicated.

"The instruments aboard the Herschel and Planck satellites need to be cooled to temperatures close to absolute zero so that emissions from the spacecraft don't drown out the faint signals that come from the very edge of the observable Universe," said Ken Wood.

"For KIDCAM, we have developed a kind of detector that can be operated in electrical coolers and therefore without the use of liquified gases. KIDCAM can be tuned to specific frequencies for specific applications, for instance to enhance the contrast between skin and plastic explosive for airport security scanners. Unwanted frequencies can be blocked to increase the camera's sensitivity. The experience that we gained working on astronomical missions has been invaluable in helping us do this. The race is now on around the world to produce devices that will realise the enormous potential of terahertz science and thanks to the ingenuity of UK astronomers we have made a great start."

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New Biosensor Microchip Could Speed Up Drug Development, Researchers Say

A single centimeter-sized array of the nanosensors can simultaneously and continuously monitor thousands of times more protein-binding events than any existing sensor. The new sensor is also able to detect interactions with greater sensitivity and deliver the results significantly faster than the present"gold standard" method.

"You can fit thousands, even tens of thousands, of different proteins of interest on the same chip and run the protein-binding experiments in one shot," said Shan Wang, a professor of materials science and engineering, and of electrical engineering, who led the research effort.

"In theory, in one test, you could look at a drug's affinity for every protein in the human body," said Richard Gaster, MD/PhD candidate in bioengineering and medicine, who is the first author of a paper describing the research that is in the current issue ofNature Nanotechnology,available online now.

The power of the nanosensor array lies in two advances. First, the use of magnetic nanotags attached to the protein being studied -- such as a medication -- greatly increases the sensitivity of the monitoring.

Second, an analytical model the researchers developed enables them to accurately predict the final outcome of an interaction based on only a few minutes of monitoring data. Current techniques typically monitor no more than four simultaneous interactions and the process can take hours.

"I think their technology has the potential to revolutionize how we do bioassays," said P.J. Utz, associate professor of medicine (immunology and rheumatology) at Stanford University Medical Center, who was not involved in the research.

A microchip with a nanosensor array (orange squares) is shown with a different protein (various colors) attached to each sensor. Four proteins of a potential medication (blue Y-shapes), with magnetic nanotags attached (grey spheres), have been added. One medication protein is shown binding with a protein on a nanosensor.

Members of Wang's research group developed the magnetic nanosensor technology several years ago and demonstrated its sensitivity in experiments in which they showed that it could detect a cancer-associated protein biomarker in mouse blood at a thousandth of the concentration that commercially available techniques could detect. That research was described in a 2009 paper inNature Medicine.

The researchers tailor the nanotags to attach to the particular protein being studied. When a nanotag-equipped protein binds with another protein that is attached to a nanosensor, the magnetic nanotag alters the ambient magnetic field around the nanosensor in a small but distinct way that is sensed by the detector.

"Let's say we are looking at a breast cancer drug," Gaster said."The goal of the drug is to bind to the target protein on the breast cancer cells as strongly as possible. But we also want to know: How strongly does that drug aberrantly bind to other proteins in the body?"

To determine that, the researchers would put breast cancer proteins on the nanosensor array, along with proteins from the liver, lungs, kidneys and any other kind of tissue that they are concerned about. Then they would add the medication with its magnetic nanotags attached and see which proteins the drug binds with -- and how strongly.

"We can see how strongly the drug binds to breast cancer cells and then also how strongly it binds to any other cells in the human body such as your liver, kidneys and brain," Gaster said."So we can start to predict the adverse affects to this drug without ever putting it in a human patient."

It is the increased sensitivity to detection that comes with the magnetic nanotags that enables Gaster and Wang to determine not only when a bond forms, but also its strength.

"The rate at which a protein binds and releases, tells how strong the bond is," Gaster said. That can be an important factor with numerous medications.

"I am surprised at the sensitivity they achieved," Utz said."They are detecting on the order of between 10 and 1,000 molecules and that to me is quite surprising."

The nanosensor is based on the same type of sensor used in computer hard drives, Wang said.

"Because our chip is completely based on existing microelectronics technology and procedures, the number of sensors per area is highly scalable with very little cost," he said.

Although the chips used in the work described in theNature Nanotechnologypaper had a little more than 1,000 sensors per square centimeter, Wang said it should be no problem to put tens of thousands of sensors on the same footprint.

"It can be scaled to over 100,000 sensors per centimeter, without even pushing the technology limits in microelectronics industry," he said.

Wang said he sees a bright future for increasingly powerful nanosensor arrays, as the technology infrastructure for making such nanosensor arrays is in place today.

"The next step is to marry this technology to a specific drug that is under development," Wang said."That will be the really killer application of this technology."

Other Stanford researchers who participated in the research and are coauthors of theNature Nanotechnologypaper are Liang Xu and Shu-Jen Han, both of whom were graduate students in materials science and engineering at the time the research was done; Robert Wilson, senior scientist in materials science and engineering; and Drew Hall, graduate student in electrical engineering. Other coauthors are Drs. Sebastian Osterfeld and Heng Yu from MagArray Inc. in Sunnyvale. Osterfeld and Yu are former alumni of the Wang Group.

Funding for the research came from the National Cancer Institute, the National Science Foundation, the Defense Advanced Research Projects Agency, the Gates Foundation and National Semiconductor Corporation.

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Search for Dark Matter Moves One Step Closer to Detecting Elusive Particle

Their new results, announced April 14 at the Gran Sasso National Laboratory in Italy, where the XENON experiment is housed deep beneath a mountain 70 miles west of Rome, represent the highest-sensitivity search for dark matter yet, with background noise 100 times lower than competing efforts.

Dark matter is widely thought to be a kind of massive elementary particle that interacts weakly with ordinary matter. Physicists refer to these particles as WIMPS, for weakly interacting massive particles. The XENON researchers used a dark-matter detector known as XENON100 -- an instrumented vat filled with over 100 pounds of liquid xenon -- as a target for these WIMPs, which are thought to be streaming constantly through the solar system and Earth.

And while the XENON100 experiment found no dark matter signal in 100 days of testing, the researchers' newly calculated upper limits on the mass of WIMPs and the probability of their interacting with other particles are the best in the world, said UCLA physics professor Katsushi Arisaka, a member of the international collaboration.

XENON100 looks for a primary flash of light that occurs when a particle bounces off a xenon atom inside the detector and a secondary flash when an electron knocked free from a xenon atom by a collision is accelerated toward the top of the device by an electric field, said UCLA physics researcher Hanguo Wang, who works closely with Arisaka. With this configuration, a WIMP will generate a signal fundamentally different from that of cosmic radiation or emission from the equipment itself, making it possible to identify background readings that could be mistaken for a positive detection, he said.

Even though the experiment did not detect a WIMP, the progress sets the stage for an ambitious next-generation project called XENON1T, which will use a much larger, one-ton liquid xenon instrument with highly specialized light-detectors developed at UCLA that make it 100 times more sensitive than XENON100, said David Cline, a UCLA professor of physics and founder of UCLA's dark matter group.

The search for dark matter

Ordinary matter, which makes up the stars, planets, gas and dust in our galaxy, emits or reflects light that can be observed using telescopes on Earth or in space. However, the effect of dark matter, according to several theories, can be observed only indirectly by the gravitational force exerted on the more visible portions of the galaxy around us, Cline said.

Despite the differences between ordinary and dark matter, cosmologists believe the two have been linked since the beginning of the universe, with dark matter playing a key role in the coalescing of particles into stars, galaxies and other large-scale structures after the Big Bang.

Though dark matter exerts a tangible force on the galaxy as a whole, individual WIMPs have proved far more difficult to detect. Because these particles interact only very weakly with normal matter, the small signal that might come from a WIMP detection above ground would be drowned out by the cosmic radiation that constantly bombards Earth's surface, Cline said.

To eliminate the majority of this background noise, the XENON100 experiment is buried beneath almost one mile of rock in the Gran Sasso lab, the largest underground facility of its kind in the world. While dark matter particles can travel easily through the vast expanse of stone and pass through the detector, only the most energetic particles from space are able to follow, Arisaka said.

Next steps

Because the XENON100 experiment is shielded by large amounts of rock, as well as by several tons of copper, lead and water, the largest source of background detections is actually the radiation coming from the instrument itself, Arisaka said.

In an effort to address this issue, Arisaka and Wang, working in collaboration with Hamamatsu Photonics in Japan, have developed the Quartz Photon Intensifying Detector (QUPID), a new light-detector technology that emits no radiation. The XENON group hopes to incorporate this breakthrough technology into the future XENON1T experiment.

"We have developed a detector to be used in future experiments based on new photon-detector technology," Wang said."We invented, tested and demonstrated its operation in liquid xenon in our laboratory at UCLA."

In addition to Arisaka, Cline and Wang, UCLA's XENON group includes postdoctoral scholars Emilija Pantic and Paolo Beltrame and graduate students Artin Teymourian and Kevin Lung. Two students, Ethan Brown and Michael Lam, received doctorates last year through this experiment.

Elena Aprile, a professor of physics at Columbia University, is the XENON collaboration's principal investigator and spokesperson.

The XENON collaboration consists of 60 scientists from 14 institutions in the U.S. (UCLA, Columbia University, Rice University); China (Shanghai Jiao Tong University); France (Subatech Nantes); Germany (Max-Planck-Institut Heidelberg, Johannes Gutenberg University Mainz, Willhelms Universität Münster); Israel (Weizmann Institute of Science); Italy (Laboratori Nazionali del Gran Sasso, INFN e Università di Bologna); the Netherlands (Nikhef Amsterdam); Portugal (Universidade de Coimbra); and Switzerland (Universität Zürich).

XENON100 is supported by its collaborating institutions and federally funded by the National Science Foundation and the U.S. Department of Energy, as well as by the Swiss National Foundation; France's Institut national de physique des particules et de physique nucléaire and La Région des Pays de la Loire; Germany's Max-Planck-Society and Deutsche Forschungsgemeinschaft; Israel's German-Israeli Minerva Gesellschaft and GIF; the Netherlands' FOM; Portugal's Fundação para a Ciência e Tecnologia; Italy's Instituto Nazionale di Fisica Nucleare; and China's STCSM.

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Better Lasers for Optical Communications

"All indications are that this technology could be useful at both industrial and scientific levels," explains Eli Kapon, head of EPFL's Laboratory of Physics of Nanostructures. More than fifteen years of research were required to arrive at this result, work that"has caused many headaches and demanded significant investment."

To obtain the right wavelength, the EPFL researchers adapted the lasers' size. In parallel, the EMPA scientists designed a nanometer-scale grating for the emitter in order to control the light's polarization. They were able to achieve this feat by vaporizing long molecules containing gold atoms with a straw-like tool operating above the lasers. Using an electron microscope, they were able to arrange and attach gold particles to the surface of each laser with extreme precision. Thus deposited, the grating serves as a filter for polarizing the light, much like the lenses of sunglasses are used to polarize sunlight.

Industrial and scientific advantages

This technique, developed in collaboration with EMPA, has many advantages. It allows a high-speed throughput of several gigabits a second with reduced transmission errors. The lasers involved are energy-efficient, consuming up to ten times less than their traditional counterparts, thanks to their small size. The technique is very precise and efficient, due to the use of the electron microscope.

"This progress is very satisfying," adds Kapon, who also outlines some possible applications."These kinds of lasers are also useful for studying and detecting gases using spectroscopic methods. We will thus make gains in precision by improving detector sensitivity."

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Battery-Less Chemical Detector Developed

The device overcomes the power requirement of traditional sensors and is simple, highly sensitive and can detect various molecules quickly. Its development could be the first step in making an easily deployable chemical sensor for the battlefield.

The Lab's Yinmin"Morris" Wang and colleagues Daniel Aberg, Paul Erhart, Nipun Misra, Aleksandr Noy and Alex Hamza, along with collaborators from the University of Shanghai for Science and Technology, have fabricated the first-generation battery-less detectors that use one-dimensional semiconductor nanowires.

The nanosensors take advantage of a unique interaction between chemical species and semiconductor nanowire surfaces that stimulate an electrical charge between the two ends of nanowires or between the exposed and unexposed nanowires.

The group tested the battery-less sensors with different types of platforms -- zinc-oxide and silicon -- using ethanol solvent as a testing agent.

In the zinc-oxide sensor the team found there was a change in the electric voltage between the two ends of nanowires when a small amount of ethanol was placed on the detector.

"The rise of the electric signal is almost instantaneous and decays slowly as the ethanol evaporates," Wang said.

However, when the team placed a small amount of a hexane solvent on the device, little electric voltage was seen,"indicating that the nanosensor selectively responds to different types of solvent molecules," Wang said.

The team used more than 15 different types of organic solvents and saw different voltages for each solvent."This trait makes it possible for our nanosensors to detect different types of chemical species and their concentration levels," Wang said.

The response to different solvents was somewhat similar when the team tested the silicon nanosensors. However, the voltage decay as the solvent evaporated was drastically different from the zinc-oxide sensors."The results indicate that it is possible to extend the battery-less sensing platform to randomly aligned semiconductor nanowire systems," Wang said.

The team's next step is to test the sensors with more complex molecules such as those from explosives and biological systems.

The research appears on the inside front cover of the Jan. 4 issue ofAdvanced Materials.

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Invisibility Cloaks and More: Force of Acoustical Waves Tapped for Metamaterials

Metamaterials are artificial materials that are engineered to have properties not found in nature. These materials usually gain their unusual properties -- such as negative refraction that enables subwavelength focusing, negative bulk modulus, and band gaps -- from structure rather than composition.

By creating an inexpensive bench-top technique, as described in the American Institute of Physics' journalReview of Scientific Instruments, Los Alamos National Lab (LANL) researchers are making these highly desirable metamaterials more accessible.

Their technique harnesses an acoustical wave force, which causes nano-sized particles to cluster in periodic patterns in a host fluid that is later solidified, explains Farid Mitri, a Director's Fellow, and member of the Sensors& Electrochemical Devices, Acoustics& Sensors Technology Team, at LANL.

"The periodicity of the pattern formed is tunable and almost any kind of particle material can be used, including: metal, insulator, semiconductor, piezoelectric, hollow or gas-filled sphere, nanotubes and nanowires," he elaborates.

The entire process of structure formation is very fast and takes anywhere from 10 seconds to 5 minutes. Mitri and colleagues believe this technique can be easily adapted for large-scale manufacturing and holds the potential to become a platform technology for the creation of a new class of materials with extensive flexibility in terms of periodicity (mm to nm) and the variety of materialsthat can be used.

"This new class of acoustically engineered materials can lead to the discovery of many emergent phenomena, understanding novel mechanisms for the control of material properties, and hybrid metamaterials," says Mitri.

Applications of the technology, to name only a few, include: invisibility cloaks to hide objects from radar and sonar detection, sub-wavelength focusing for production of high-resolution lenses for microscopes and medical ultrasound/optical imaging probes, miniature directional antennas, development of novel anisotropic semiconducting metamaterials for the construction of effective electromagnetic devices, biological scaffolding for tissue engineering, light guide, and a variety of sensors.

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New Nanomaterial Can Detect and Neutralize Explosives

"This stuff is going to be used anywhere terrorist explosives are used, including battlefields, airports, and subways," said study leader Allen Apblett, Ph.D."It's going to save lives."

The material is a type of ink made of tiny metallic oxide nanoparticles -- so small that 50,000 could fit inside the diameter of a single human hair. The ink changes color, from dark blue to pale yellow or clear, in the presence of explosives. It also changes from a metallic conductor to a non-conducting material, making electronic sensing also possible.

This color-change feature allows the material to work as a sensor for quickly detecting the presence of vapors produced by explosives, Apblett said. Soldiers or firefighters could wear the sensors as badges on their uniforms or use them as paper-based test strips. Airports, subways and other facilities could use the sensors as part of stationary monitoring devices. The sensors could even be engineered into jewelry and cell phones, the scientist added.

The same color-changing material can also serve as an explosives neutralizer. Firefighters and bomb squad technicians could spray the ink onto bombs or suspicious packages until the color change indicates that the devices are no longer a threat, Apblett said. Technicians could also dump the explosives into vats containing the ink to neutralize them.

Apblett notes that authorities are concerned about peroxide-based explosives, made from hydrogen peroxide, which are easy to make and set off. These explosives first drew public attention in 2001, when thwarted"shoe bomber" Richard Reid tried to use one such substance as the detonator onboard a commercial airliner. In particular, they are concerned about a substance called triacetone triperoxide, or TATP, sometimes used in suicide vests and improvised explosive devices that have claimed such a toll among troops and civilians. However, current methods of detecting this explosive are ineffective, allowing the material to easily escape detection at airports and other locations.

The new ink provides a quick way to detect and test these explosives, which might be hidden in clothing, food, and beverages. The ink contains nanoparticles of a compound of molybdenum, a metal used in a wide variety of applications including missile and aircraft parts. The dark blue ink reacts with the peroxide explosives and turns yellow or clear.

When used as an electronic sensor, the highly-sensitive material is capable of detecting TATP vapors at levels as low as a 50 parts per million, equivalent to a few drops of the vapor in a small room, within 30 seconds. The same chemical reaction allows the materials to serve as an explosives neutralizer. In lab studies, the scientists showed that they could add the material to TATP or HMTD and make them nonexplosive.

"This does a really good job of neutralizing terrorists' explosives," said Apblett, a chemist at Oklahoma State University in Stillwater, Okla."I'm excited to see it moving from the lab to the real world."

The material can also improve safety at laboratories that use explosive chemicals. Recently, Apblett developed pellets containing the ink that can be added to laboratory solvents to prevent the build-up of levels of dangerous peroxides, which can cause accidental explosions. The color-changing feature allows the users of the solvents know that they are safe.

Apblett and colleagues founded a company called Xplosafe to develop and market the material. They hope to see the explosive detecting ink used in airports in as little as a year.

The scientists acknowledge funding from Memorial Institute for the Prevention of Terrorism, the National Science Foundation, Oklahoma Center for the Advancement of Science and Technology, Xplosafe, and Oklahoma State University.

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