Japanese researchers have developed an odor-detecting sensor that responds to the smell of human sweat. Embedding it in an artificial cell membrane, they have developed a mobile robot mounted with the sensor that kicks into motion when detecting the smell given off by a particular substance.

Such applications may one day play a vital role in search-and-rescue operations during disasters, the researchers say.

A locomotive robot equipped with an odor sensor moved to the right when a filter paper immersed in octenol was held over its odorant sensor. Image credit: ©Shoji Takeuchi Research Group. The research team—led by Professor Shoji Takeuchi, at the University of Tokyo Institute of Industrial Science; researcher Nobuo Misawa, at Kanagawa Academy of Science and Technology; and collaborators at Sumitomo Chemical—developed the odor-detecting sensor from a membrane protein found in the antenna of mosquitoes called an olfactory receptor. While scientists in various countries have developed sensors that detect odors, these devices pale in comparison to a living creature’s organ in terms of compactness, sensitivity and selectivity in distinguishing smells, according to the researchers.

The olfactory receptor used in the current study responds only to a substance called octenol, an odor component of human sweat, which changes the membrane’s conductivity, or the ease with which electricity passes through it. A mosquito identifies human odor by detecting this change in electrical current.

The researchers installed the sensor—the membrane embedded with the mosquito protein—into a small wireless device and mounted it on a locomotive robot. They succeeded in demonstrating that when octenol is released in the air around the robot, it responds by moving.

The team aims to develop practical applications for the sensor that will help rescuers search for missing people in disasters and other situations when visual confirmation is difficult. Takeuchi adds that using the olfactory receptors of insects other than the mosquito could yield the potential for using them to detect illegal drugs and explosives.