However, what if there were a low-cost "electronic nose" that was even better at detecting those things, providing us with an earlier warning? That's what's being developed at Germany's Karlsruhe Institute of Technology.
Part of the university's "smelldect" project, the prototype device is just a few centimeters in size, and incorporates a sensor chip connected to multiple individual sensors – each of those sensors is in turn made up of an array of tin oxide nanowires, which have a very high electrical resistance.
When the device is being used, however, that resistance is temporarily lowered by irradiating the wires using an ultraviolet LED that's built into the sensor housing. Once the airborne molecules that make up an odor settle on the nanowires, that resistance decreases further. By noting the specific amount of decreases in resistance, on specific sensors, the device is able to establish a pattern for the odor. It then compares that pattern to those for various known odors, which have already been programmed into it, and within seconds lets the user know if it finds a match.