The metal detector has received a dolphin-inspired upgrade. A new technique distinguishes electronic gadgets from other metals, potentially aiding first responders and law enforcement agents.
Inspired by the way dolphins hunt fish by lassoing them with strings of bubbles, physicist and engineer Timothy Leighton of the University of Southampton in England builds sonar devices that differentiate between underwater bubbles and objects such as fish and naval mines (SN: 8/25/12, p. 12). The key is emitting two nearly identical sound pulses; by comparing the pulses that return, Leighton can separate bubbles, which scatter sound, from objects that reflect it.
Now Leighton has applied the same concept to radio waves, or radar, which can detect metal. He emitted dual pulses at an aluminum plate, a rusted clamp and an electric circuit. The circuit scattered radio waves in a predictable way, so Leighton could easily identify the pulses that had struck the circuit, he and his team report October 22 in the Proceedings of the Royal Society A.
Similar circuits appear in cell phones and eavesdropping devices, Leighton says, so the technique could be used to locate survivors of an avalanche or building collapse and to determine whether a room is bugged.
