Developed by researchers in the UK, metabolite sensors detect ammonia and carbon dioxide produced by victims when they breathe, sweat and urinate. They are sensitive and let rescuers detect small amounts of these compounds in the air pockets of a collapsed building.
Rescue dogs also detect these metabolites but the sensor technology is better. Dogs, like people are limited physically. They get hungry, tired and distracted. And the search itself can be dangerous to both the animal and its handler. Sensors, well, they just keep processing data without stopping for food or water until they die from battery depletion. [Australian Geographic]