The pressing need to find better ways to detect WMD agents continues to attract new ideas. In two recent developments, existing technologies devised for other purposes have been adapted for these more sobering uses.

In the first, the U.S. Army has asked scientists at the Massachuesetts Institute of Technology's Lincoln Laboratory to see if the same Doppler radar used to generate those colorful weather pictures seen on TV can be employed to provide early warning of biological and chemical agents used in terrorist attacks.

The sensitive system is ideal for detecting the structure and movement of storms. Doppler radar uses a saucer-shaped dish to sweep local space, sending a directed pulse of energy into the sky. When that energy encounters raindrops, for instance, a small part of the energy bounces back to be picked up and processed by computers. The resulting data map reveals the number and size of raindrops and their velocity toward or away from the dish.

Lincoln Laboratory wants to use existing Doppler radar towers that it helped design to provide automatic alerts of dangerous wind shear conditions, in effect piggybacking an early warning system for chemical or biological agents disseminated by airplanes. The towers are at 45 major airports.

The U.S. Army's Homeland Defense Chemical Biological Umbrella program conducted the first of a series of tests two years ago to prove the concept. Last year, Lincoln Laboratory was enlisted to develop software that would scan Doppler data for something with a profile different from snow, rain, insects or other natural phenomena.

In one test, a Cessna crop duster disseminated water mixed with antifreeze at an altitude of about 1,200 feet using specific release rates and aircraft speeds. In another, a harmless ground-up clay was dispersed to simulate particulate spores like anthrax.

“From a radar detection viewpoint, water or clay are quite similar in appearance to biological or chemical warfare agents,” said Lincoln Laboratory group leader Mark E. Weber. The challenge will be to create software that can point to a plume that looks different enough from natural elements to warrant suspicion.

A prototype of the detection system will be tested this spring on a non-operational Federal Aviation Administration radar tower in Oklahoma City. If successful, the army intends to equip a number of additional towers around the country with this capability.

In another technological adaptation, the ability to analyze and defend against new biological agents may become a reality with enhancements to an existing device developed at Vanderbilt University to monitor the metabolism of living cells in near real-time.

“So far, we've been lucky that terrorists have only used well-known biological agents like anthrax and sarin gas,” said David Cliffel, Vanderbilt assistant professor of chemistry. “But how will we respond if one of these groups uses recent advances in genetic engineering to produce a new, unknown agent?”

Cliffel said one answer is Vanderbilt's four-channel microphysiometer, a modification of an existing commercial device called the Cytosensor from Molecular Devices of Sunnyvale, Calif., that measures changes in acidity in a small chamber holding between 100,000 and one million cells.

The Vanderbilt team added three additional sensors so that the machine can simultaneously chart minute-by-minute variations in the concentrations of oxygen, glucose and lactic acid, in addition to pH levels — an important modification because the basic metabolism of a cell involves consuming oxygen and glucose and producing lactic and carbonic acid.

As a result, monitoring variations in these four chemicals allows researchers to quickly assess the impact that exposure to different chemicals has on the activity and health of relatively small groups of cells.

Cliffel envisions having a microphysiometer with an array of chambers, one of them containing heart cells, another containing kidney cells, another nerve cells, and so on.

“Then, when an unknown agent is pumped into all these chambers, we quickly will be able to determine exactly which part of the body it attacks, and the response of the affected cells will provide us with important clues about the manner of its attack,” Cliffel said.

Because of its potential application for bioterrorism and chemical warfare, the development of the device has been funded by the Defense Advance Research Projects Agency.