Smoldering Fire Detection Using Low-Power Capacitive MEMS Hydrogen Sensor for Future Fire Alarm

In this paper, we demonstrate detection of a smoldering fire by using a low-power hydrogen sensor. To detect the low levels of hydrogen gas generated by smoldering fires, a capacitive MEMS hydrogen sensor with a microheater was proposed. The microheater improved hydrogen sensitivity on the order of ppm by accelerating the oxide desorption at the sensing film surface. Low thermal capacity and high thermal resistance structure enabled localized heating of the sensitive film at a highspeed of 1 ms, thereby achieving sub-mW low power consumption by intermittent sensing operation. The fabricated hydrogen sensor was installed in a small wireless module and placed on the ceiling 3 meters from the cotton fire source. Our hydrogen sensor successfully detected 66 ppm hydrogen generated by the smoldering fire, and also detected the elimination of hydrogen by exhaust.