Researchers in Germany have developed a sensor for smartphones, or even robots, that can be taught different scents based on specific signal patterns. The “Smelldect” program can sniff out everything from spoiled foods to potential air hazards, even acting as a smoke alarm.
According to researchers at the Karlsruhe Institute of Technology (KIT) in Germany, the electronic nose only is a few centimeters in size. It contains the electronics needed, including the technology to evaluate the gases.
The "nose" consists of a sensor chip equipped with nanowires made of tin dioxide on many individual sensors. The chip calculates specific signal patterns from the resistance changes of the individual sensors. These depend on the molecules in ambient air, differ for the different scents and, hence, are characteristic and recognizable. If a specific patterns has been taught to the chip before, the sensor can identify the scent within seconds.
The sensor chip can be used for various purposes: In the household for the control of ambient air or as smoke alarm, during shopping to find out how fresh the fish or meat is, or even as a nose of a robot.
"The difficulty consists in the fact that a scent does not always remain the same. For instance, the smell of a rose in the sun differs from that of a rose in rain," Dr. Martin Sommer says. "Currently, we are training the electronic nose for specific uses which can be chosen universally however."
The scientists of KIT want to develop a low-cost sensor for the mass market.
"In the future, the electronic nose might be incorporated into all electric devices in order to prevent cable fires. Or it can be used in smartphones. When going shopping, everybody might be accompanied by his/her own highly sensitive electronic nose," Sommer says.