FLIPPER would be impressed. Dolphin clicks have inspired the development of a cheap, coin-sized radar gadget that can sense hidden electronics. The device could be used to find covert surveillance bugs, bomb triggers or timers – even if they are hidden in large piles of clutter or garbage.
While watching a nature show, acoustics engineer Timothy Leighton of the University of Southampton, UK, wondered why dolphins blow clouds of bubbles from their blowholes to corral fish. Surely, he thought, these "bubble nets" must reflect sonar clicks and wreck the dolphin's ability to locate their prey? "Even the best man-made sonar couldn't distinguish between the fish and bubbles," he says. "There had to be something else going on."
By experimenting with different forms of acoustic signals, he found that a large pulse followed by a small one could reflect sound waves in such a way as to allow fish and bubbles to be easily distinguished. "We built a sonar that did this and took it out to sea and it worked beautifully," Leighton says, though he adds that he isn't sure this is how dolphins detect their prey.
The same technique should also work with radio waves, so Leighton built a prototype radar and tested it. He found it could tell the difference between a wide range of materials (Proceedings of the Royal Society A, DOI: 10.1098/rspa.2013.0512).
The radar is small – about 2 centimetres across – and Leighton says it can be built for just €2. "If you have bombs hidden in roadside rubbish like plastic bags, wood scrap, bike wheels and drinks cans it distinguishes the interesting devices – those containing metal wires and semiconductors – so you might pinpoint a bomb circuit for instance," he says.
It could also be used after an earthquake to locate people buried in rubble by seeking their iPods or phones.
"This advanced radar shows promise," says Gary Kemp, programme director at Cambridge Consultants in the UK. Any technology that increases the probability of detecting improvised explosive devices or buried casualties will undoubtedly save lives, he says. "Evolution has once again sparked ideas for remarkable innovation."
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