With millions of unexploded land mines and bombs left scattered around the world from various conflicts, there is a humanitarian need for a low-cost technology that can locate these threats to civilians. Researchers at the University of California in San Diego have demonstrated a TNT sensor made of nanowires that may fit the bill.

The sensor comprises silicon nanowires coated with a polymer that luminesces under ultraviolet light unless it comes in contact with TNT molecules or picric acid, another explosive. By monitoring quenching of the luminescence, the researchers detected TNT at 4 ppb in air and 50 ppb in seawater, and picric acid at 6 ppb in seawater.