MQ135 Air Quality Sensor Module – NH3 NOx CO2 Detection

The MQ135 Air Quality Sensor Module is a semiconductor gas detection module designed for indoor air quality monitoring and environmental measurement systems. It utilizes an SnO2 sensing element with stable sensitivity to NH3, NOx, CO2, benzene vapor, and smoke. Operating at 5V DC, the module provides both analog and digital TTL outputs with an adjustable threshold potentiometer for flexible integration. Built for reliable long-term operation, it ensures consistent response and recovery characteristics. Suitable for air quality stations, embedded control systems, and educational development platforms.