The Okdo MQ135 sensor uses SnO2 sensitive material on the ground that SnO2 has low electrical conductivity in the clean air. When surrounded by the polluted air, the electrical conductivity of MQ135 sensor will increase with the increase of pollutants, and changes of electrical conductivity can be converted to corresponding output signal. You can rotate the potentiometer on the sensor to adjust the sensitivity. MQ135 has a high sensitivity to ammonia, sulfide, benzene vapor, smoke and other harmful gases.

Compatible with RJ11 6P6C OKdo TelePort Control boards and expansion shields
Suitable for aromatic compound detection including ammonia (NH3), NOx, benzene, smoke, CO2andothergases
Long stable service life with reliable fast response and recovery featur