WHEN it comes to finding hidden explosives, the self-propelled detection system known as a sniffer dog has no equal. But sniffer dogs have to be trained, and that is a delicate process. In particular, the trace levels of explosive vapour involved are so low (because dogs’ noses are so sensitive) that accidental contamination of supposedly residue-free “control” samples is a serious possibility. That confuses the animal and slows down its training. Things would therefore go more smoothly if a trainer could find out instantly whether a sample had indeed been compromised by traces of explosive, so that he could tell whether a dog’s reaction to a supposed blank was justified.
This is no theoretical risk. When Ta-Hsuan Ong of the Massachusetts Institute of Technology monitored one such training session he found that six out of 68 controls were contaminated—and that one out of 28 supposedly “live” samples had no explosive residue. Dr Ong thinks, however, that he has a…Continue reading