KS0047 keyestudio MQ135 Air Quality Sensor

1. Introduction

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.

MQ135 has a high sensitivity to Ammonia, sulfide, benzene vapor, smoke and other harmful gas.

It can detect various harmful gases, making it a cost-effective choice suitable for multiple applications.

2. Specification

  • Product model: MQ135

  • Product type: Semiconductor gas sensor

  • Target gas: Ammonia; methylbenzene; hydrogen

  • Ÿ Standard circuit: Loop voltage Vc ≤24V DC

  • Heater voltage: VH 5.0V±0.2V AC or DC

  • Load resistance: Adjustable RL

  • Heater power consumption: PH ≤900mW

  • Sensitivity: S Rs(in air)/Rs(100ppmNH3)≥5

  • Concentration slope: α ≤0.6 (R100ppm/R50ppm NH3)

  • Standard testing temperature/humidity: 20℃±2℃/65%±5%RH

  • Standard testing circuit: Vc:5.0V±0.1V; VH: 5.0V±0.1V

  • Preheating time: ≧48H

3. Connection Diagram

4. Sample Code

Download code：Code

void setup() 
{
  Serial.begin(9600);
}

void loop() 
{
  int sensorValue = analogRead(A0);
  Serial.println(sensorValue, DEC);
}

5. Result

Open the Serial monitor to check the pollution index of the air surrounds you:

image-20251226095107603