Harvard researchers have married a smartphone to a metal detector to create PETALS, a low cost way to improve mine detection in third-world countries. Traditionally, locating land mines has required a carefully trained ear to distinguish deadly explosives from, say, a can. This new system removes some of the guesswork by mapping the beeps on a cell phone screen, creating a silhouette of whatever is beneath the surface. Similar results have been accomplished using acoustic sensors, but so far they've been relegated to research projects and would likely be too expensive for use where they're needed mos
