Indeed, sensors can take lessons from some real noses. Sandia scientists are assisting a company called Nomadics in Stillwater, Okla., in developing a chemical sniffer. Trying to emulate what dogs do when they inhale and exhale near the ground, the sniffer stirs up dirt particles, sucks them in, and electrostatically traps them. Traces of explosives that stick to the particles can then be identified. Only minor fractions are found in vapor.
Soil concentrates the substances so that they can be analyzed more easily.
O rganisms that can be added to soil also play a part in explosives detection. When certain bacteria ingest organic molecules, they turn on the production of regulatory proteins. In this way, glowing bacteria signal the presence of the explosive in the environment. Burlage is presenting the results of this project at the Third International Symposium on Technology and the Mine Problem to be held at the Naval Postgraduate School in Monterey, Calif., next week. Later this year, the group will test the bacteria on a small simulated minefield, spraying the plot of land with the bacteria and waiting 3 hours for them to produce the glowing proteins.