This is no mean feat, since the device must pick out the one "stinky" smell denoting danger from many benign ones. It requires enormously complex and precise differentiation and filtering capabilities.
別以為這是雕蟲小技，試想，要在各種氣味混雜、濃度飄忽不定的情況中獨「嗅」一味，需要多麼精密複雜的辨識及篩選功力！