Identifying Terrorists by Smell. No, it's not Racial Profiling

Researchers at the Fraunhofer Institute for Communication, Information Processing and Ergonomics FKIE in Wachtberg, Germany, have built a prototype security system called HAMLeT, which stands for Hazardous Material Localization and Person Tracking,
that can help identify terrorists by capturing the smell of explosives.

The smell sensors sound the alarm when they detect explosive materials, alerting airport security. The sensor network will continue to “sniff out” and track down the suspect for security to apprehend.

When the sensors capture chemical molecules, oscillating crystals on the sensor chips change frequencies. Different frequencies are programmed for different substances. The sensor’s data fusion function traces the explosive’s path and ferrets out the carrier. A second sensor network is needed to track the route the individual takes; for this, the researchers have used laser scanners.

In a trial involving the German Armed Forces, researchers were able to track down five fake terrorists carrying hidden explosives. The scientists are now working to refine the prototype’s algorithms in order to reduce the false alarm rate.