May 23, 2003 

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Secret Sensor (video)
March 27, 2003

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Interviewees: Terry Michalske and Jeffrey Brinker, Sandia National Laboratories.

Video is 1 min 17 sec long. Please be patient while it loads enough to start playing.

Produced by Ann Marie Cunningham

Copyright © ScienCentral, Inc., with additional footage from NBC News.

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The Role of Sensing & Sensors - Sandia Technology

Nanotechnology research for homeland security and national defense also goes on at MIT’s Institute for Soldier Nanotechnology and Florida State University

If you worry about war coming home, in the form of bombs or bioterror, there are some high-tech defenses in place. One is an extremely efficient sensor in our airports and subway stations.

As this ScienCentral News video reports, the new device is particularly sensitive to hidden explosives or chemical weapons like nerve gas, thanks to a special component that was inspired by tumbleweed.

Rolling Homeland Security

Around Sandia National Laboratories and the University of New Mexico in Albuquerque, where senior scientist and professor C. Jeffrey Brinker develops new materials, the windy late-winter months can choke paths and gardens with tumbleweed. Brinker was struggling to clear piles of the rolling irritant off his lawn, when he realized that while tumbleweed takes up a great deal of room, it is actually mostly open space, with very little solid material. “If you look at a tumbleweed,” he says, “you see that it’s almost all surface. There’s not very much meat; it’s almost all bone.” He decided to try to make a glass-based material that was just as open, or porous, but on an extremely tiny scale, the molecular level.

Brinker, who now keeps a big tumbleweed hanging from his office ceiling, came up with a “tumbleweed in a beaker”--an extremely thin, honeycomb-like film. Like tumbleweed, the film is made up almost entirely of pores. Brinker refers to the film’s pores as “nanopores” because their diameter is only a few nanometers, the size of several atoms.

The new film’s nanopores are not only incredibly tiny, but very close together--which means that they can trap and concentrate gas molecules very easily. At Sandia’s Center for Integrated Nanotechnologies, director Terry Michalske saw that Brinker’s nanoporous film could become the heart of a new, more efficient sensor. According to Michalske, soldiers in the field during the 1991 Gulf War were equipped with sensors that tended to sound an alert “every time someone lit a cigarette or fired up a diesel engine.” On battlefields and at home, sensors had to be very sensitive, but also extremely discriminating, alerting their users only to real threats.

At the center that Michalske oversees, Brinker’s film was incorporated into a brand new sensor no larger than a cell phone. These sensors are now in domestic airports and subway train stations, though their exact locations are secret. In relatively confined spaces, like station corridors or airport security checkpoints, where the air is more concentrated, the new sensor can pick up all gases exuding from clothing, suitcases or backpacks. Inside the sensor, gas molecules collect in the film’s nanopores. Under the film, a metal strip heats up, releasing the molecules into a miniature detector for instantaneous analysis. The whole process can tell whether a traveler is carrying something dangerous in less than a second.

Overseas, Brinker’s inspiration from tumbleweed has rolled into the current Gulf War. According to Michalske, sensors that carry Brinker’s film are also flying on drones in Iraq, on the lookout for chemical weapons.

Their work, which has been published in the journals Nature and Science, was supported by the National Science Foundation, the Department of Energy, and the Defense Advanced Research Projects Agency.

by Ann Marie Cunningham

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