From the article: America can breathe easy. Well, easier. Since 9/11, researchers in government labs around the country have been hard at work improving our ability to detect deadly airborne substances that terrorists might use to attack urban centers.

In Chicago's Argonne National Laboratory, a Department of Energy research facility, scientists believe they have made a significant advance in identifying nasty pathogens such as anthrax, ricin or botulism that terrorists might release into an environment. The technology can also be used by doctors to diagnose sick patients without having to wait for a lab to send back the results of a blood test or a cheek swab.

Argonne's breakthrough, called the "biochip," starts with a slide covered in thousands of tiny polymer gel droplets. Each droplet is about 100 microns in diameter, the width of a human hair, and is designed to target a specific pathogen. Billions of "probes" consisting of DNA strands, proteins, peptides or antibodies are inserted into every droplet. A smallpox droplet, for example, will have only smallpox probes.