The U.S. military wanted to investigate the potential of "insect reconnaissance," so University of New Mexico chemical engineer C. Jeffrey Brinker answered the call.

The initial idea was to maintain honeybee colonies and analyze the nectar and pollen that foraging bees brought back to the hive, looking for traces of explosives, toxins or bioweapons.

Then Brinker and his colleagues pursued the notion of mounting tiny chips on the backs of honeybees and cockroaches. That was six or seven years ago, he said.

Sensors on the chips would flash bright green when the bugs encountered dangerous agents, Brinker said Wednesday in Denver at the annual meeting of the American Physical Society.

For various reasons, the Defense Advanced Research Projects Agency, the main research-and-development arm of the Defense Department, pulled the plug on Brinker's bug funding in 2002.

But he has continued to pursue the idea of "microbe-based biosensors," using individual living cells embedded in ultrathin, glasslike films. The microscopic cells - Brinker started with yeast cells and later tried various bacteria - are surrounded by fats to seal in water and provide nutrients.

"I was trying to make a self-contained, self-sustaining environment for the cell," he said. The cells can survive for weeks or months.

Brinker and his colleagues genetically altered the cells so they fluoresce when they encounter traces of toxins, explosives, or pathogens such as anthrax.

A million of the living cells could be placed on a chip less than half an inch square. Cells on a single chip could detect a variety of hazardous substances, Brinker said. Reservoir water could be monitored for contaminants by coating countless beads with the cell-based sensors, then running water over the beads and checking them under a microscope for bright-green fluorescence.

More than 7,000 physicists are in Denver this week for the American Physical Society's annual meeting.