Bomb detector inspired by dolphin sonar

New Scientist : By studying dolphins blowing bubbles, acoustics engineer Timothy Leighton of the University of Southampton in the UK has come up with a device to detect explosives and electronics. While watching a nature show, Leighton observed dolphins blowing a cloud of bubbles to encircle fish like a net; he wondered how the animals’ echolocation could distinguish between the bubbles and the fish. Leighton used radio waves to send twin pulses, a large one followed by a smaller one—just as dolphins do. He found that the technique allowed him to distinguish among a wide range of different materials. The small, lightweight device he developed, which is inexpensive to produce and requires no batteries, could have a variety of uses besides bomb detection, including looking for people buried after an earthquake by searching for their iPods or cellphones.