 The chemiresistive material they investigated was copper phthalocyanine, and they demonstrated that its resistivity decreased in the presence of ammonia vapour at room temperature.In recent years chemiresistor technology has been used to develop promising sensors for many applications, including conductive polymer sensors for secondhand smoke, carbon nanotube sensors for gaseous ammonia, and metal oxide sensors for hydrogen gas.The ability of chemiresistors to provide accurate real-time information about the environment through small devices that require minimal electricity makes them an appealing addition to the internet of things.