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February 09 Issue - Employee Monthly Magazine
Coming to an airport near you
Scientists develop machine to ID liquids
Andrei Matlashov of Applied Modern Physics places bottles of shampoo, water, and other liquids on a conveyor belt for analysis by the MagViz machine at Albuquerque International Sunport. Photo by Richard Robinson
Air travelers at Albuquerque International Sunport were just a few feet away from a remarkable new security device in December, if only they had peeked around the corner into the old Gate D area. The area, no longer in use for airline service, was transformed briefly into a security device test bed for a Los Alamos demonstration for the Department of Homeland Security and the media, plus a little "tire kicking" by the Transportation Safety Administration.
The object of their attention was MagViz, an innovation originally intended to take pictures of the brain using a new, ultra-low-field magnetic resonance imaging (MRI) system. Instead of the powerful magnet used in a traditional medical MRI, the Los Alamos device uses an ultra-low-field magnet similar in strength to the magnetic pull of the Earth--about 46 microteslas. By contrast, hospital MRI machines create a magnetic field 10,000 to 100,000 times Earth's magnetic field.
To make sense of the faint signals from the new machine's low field, the technology relies on sophisticated detectors called superconducting quantum interference devices, or SQUIDs. Whereas a hospital MRI detects spin with a sensor akin to a radio antenna, tuned to a specific set of frequencies, SQUIDs can pick up the oscillation of hydrogen or other atoms at any frequency.
Linked to a computer database, MagViz can now reliably identify some 50 liquids by their chemical fingerprints. And that's only the beginning. "That's one of the beauties of this technology," project leader Michelle Espy said. "We can add different threats as we become aware of them."
If MagViz finds a chemical designated as a threat, the machine will mark the container with a red dot on the screen. Harmless substances get a green dot, and if the machine can't identify the liquid, a yellow dot appears, indicating that further inspection is needed. As new threats emerge, "we just put them in the database and set the gate," Espy said.
The screen of the MagViz unit displays each tray of liquid or gel items, with the target materials highlighted by color according to potential risk. Photo by Richard Robinson
In MagViz's current incarnation, the entire process takes a minute, from applying the magnet to producing the image. The Homeland Security Advanced Research Project Agency at the U.S. Department of Homeland Security Science and Technology Directorate, which is supporting this project with a $5 million grant, hopes the final version eventually will be able to scan bags at a speed similar to the current security checkpoint X-ray machines.
Former project leader Robert Kraus hopes that MagViz will be helpful to security by reducing the chance that dangerous substances can make it onto airplanes, while simultaneously allowing passengers the convenience of traveling with liquids as they did before 2006. And the team is aiming for a system that allows travelers to leave everything in their bags, decreasing time spent waiting in security lines.
The project came to life about two years ago, as an interdisciplinary team of Los Alamos researchers and students coaxed fuzzy brain images from the low-field prototype. In the process of developing the brain scanner, then-project-leader Kraus and his team seized upon the idea that a versatile, low-field MRI might have applications beyond medicine. The researchers hypothesized that they might be able to distinguish between different liquids. "Different parts of the brain are all very similar in their chemical makeup," said Espy, and yet the contrast allows doctors to differentiate aspects of the brain.
Starting with commonly available substances, the team found the system to be remarkably discriminating. "If we can tell the difference between V8 juice and Coca-Cola, which are mostly water," Kraus said, "why can't we tell the difference between shampoo and a threat substance?"
Having liquids on airplanes has been an issue in air travel security since measures were implemented in 2006 to address the threat of terrorists using liquid explosives onboard aircraft. Today, the "3-1-1 rule," which requires that all carry-on liquids be kept in 3-ounce bottles in a single one-quart, zip-top bag, remains a frustration to weary travelers. A solution might well be at hand.
--Nancy Ambrosiano and John C. Cannon
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