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A Tiny Trampoline To Gauge Magnetism


Developments to Watch

A TINY TRAMPOLINE TO GAUGE MAGNETISM

EXOTIC METAL ALLOYS and other new materials could be the keys to powerful new computer chips and other electronic devices. But it helps if scientists can first determine the materials' magnetic properties. One way is to expose a sample to a massive magnetic force 1 million times that of the earth's magnetic field. Scientists create this force with a pulse of electricity that lasts one-hundredth of a second. There's just one problem: Measurements are difficult because the field disappears so quickly.

Physicist David J. Bishop and his colleagues at Lucent Technologies Inc.'s Bell Laboratories have an ingenious solution for split-second magnetic measurement. Following the principle that "fleas are faster than elephants," as Bishop puts it, his team designed a tiny trampoline just 300 microns across--about three times wider than a human hair (picture). Anchored by four springs, the trampoline's net is stretched just above a fixed electrical plate.

In the center of the trampoline, the researchers put a one-microgram speck of material. When they flick the switch on the magnet, the sample is pulled toward the plate. The amount of movement indicates the sample's degree of magnetization, Bishop says. "The trampoline is so small that it can move in the same time scale as the magnetic force." In April, Bishop proved the device works by testing the magnetization of a superconductor with properties that are already known. The results are described in the May 1 issue of Science.EDITED BY NEIL GROSSReturn to top

HEY, KIDS--LET'S BUILD A LEGO ROBOT

LEGO FANS WILL SOON PLUNGE into the realm of robotics. In October, the Danish toymaker will launch Lego Mindstorms, which pairs its familiar colored plastic bricks with chips and electronic sensors.

Inspired by research at Massachusetts Institute of Technology's Media Laboratory, the new Mindstorms kits will be priced at $219. Each will contain a motor, batteries, and a microprocessor-enhanced brick called an RCX--as well as the usual blocks, wheels, and gears. Children will be able to program robots to perform specific functions, such as scampering into the corner of a room when a light is turned on or navigating an obstacle course. Budding programmers will write rules for their robots on a PC, using simple drag-and-drop icons. Then, they'll transfer the programs into the RCX brick through an infrared link. Unlike earlier computer-enhanced Lego robots, Mindstorms creations will be wireless and autonomous. And kids will be able to share ideas and download each other's RCX programs at a Lego Web site.EDITED BY NEIL GROSSReturn to top

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GIVING EXPLOSIVES A `SIGNATURE'

MORE THAN 20 YEARS AGO, chemists in the U.S. figured out how to tag batches of explosives with unique, multicolored plastic particles. The idea was to help police track terrorists, but it never caught on: The mixtures may not perform exactly like the original chemicals.

Chemical startup Isonics Corp. of San Jose, Calif., thinks "taggants" make sense, but plastic is the wrong solution. President and founder James E. Alexander says the best approach is to replace some of the elements in explosives with their stable (nonradioactive) isotopes. These are synthetic and naturally occurring twins of such atoms as hydrogen, carbon, nitrogen, and oxygen--the key ingredients in most explosives. Alone and in combination, isotopes behave exactly like their more common atomic twins. But when examined with high-powered imaging tools, such as magnetic resonance imaging, different batches of stable isotope-laced chemicals--or their explosive residues--would display unique signatures.

Isonics isn't the first company to explore stable isotope tagging. The technique has been used to help gasoline companies track their products. But Alexander thinks Isonics will have a cost advantage, thanks to high-volume production techniques obtained through a partnership with the Institute of Stable Isotopes in Tbilisi, Georgia. The institute used to provide the Soviet nuclear-weapons program with isotope expertise, including techniques for enriching uranium.EDITED BY NEIL GROSSReturn to top


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