ks0047 keyestudio MQ135 air quality sensor module HD

http://www.amazon.com/dp/B0176BGS6U MQ135 adopts SnO2 as its gas sensitive material because SnO2 has low electrical conductivity in the clean air. So when surrounded by polluted air, the electrical conductivity of MQ135 will increase with the increase of pollutants, and the change in electrical conductivity can be converted to corresponding output signal.