Product Description
The MQ-138 Gas Sensor Module is a highly sensitive, low-cost solution for detecting formaldehyde (HCHO), volatile organic compounds (VOCs), and other harmful gases in indoor and industrial environments. Manufactured by Winsen Electronics, the MQ-138 uses a SnO₂ (tin dioxide) semiconductor sensing material, which changes conductivity in response to the presence of organic vapors.
With excellent sensitivity to toluene, acetone, alcohol, methanol, hydrogen, and other organic gases, this module is widely used in air quality monitoring, VOC gas alarms, industrial leakage detection, and portable air detectors. It features an alarm signal light for instant gas detection feedback, making it a practical choice for both professional and DIY air monitoring applications.
Technical Specifications
Model: MQ-138
Sensor Type: Semiconductor gas sensor
Encapsulation: Bakelite with metal cap
Target Gases: Formaldehyde (HCHO), toluene, acetone, alcohol, methanol, hydrogen, and organic vapors
Detection Range: 5 – 500 ppm
Loop Voltage (Vc): ≤ 24V DC
Heater Voltage (Vh): 5.0V ± 0.1V (AC or DC)
Heater Resistance (Rh): 29Ω ± 3Ω (room temperature)
Heater Consumption (Ph): ≤ 900 mW
Load Resistance (RL): Adjustable
Sensitivity (S): Rs (in air) / Rs (in 50 ppm toluene) ≥ 2
Output Voltage (△Vs): ≥ 0.5V (in 50 ppm toluene)
Concentration Slope (α): ≤ 0.6 (R200ppm / R50ppm toluene)
Standard Test Conditions: 20℃ ± 2℃, 55% ± 5% RH
Operating Circuit: Vc 5.0V ± 0.1V; Vh 5.0V ± 0.1V
Preheat Time: > 48 hours
Key Features
High sensitivity to formaldehyde (HCHO) and volatile organic compounds (VOCs)
Reliable detection of toluene, acetone, alcohol, methanol, hydrogen, and other gases
Low-cost solution for multi-gas monitoring applications
Adjustable load resistance for calibration flexibility
Alarm signal light for real-time detection feedback
Suitable for both domestic and industrial applications
Applications
Indoor air quality monitoring systems
VOC gas alarms for households and workplaces
Industrial gas leakage alarms and safety systems
Portable VOC/formaldehyde detectors
Environmental monitoring and IoT-based sensor networks
Package Includes
Why Choose This Sensor?
The MQ-138 module combines sensitivity, reliability, and affordability in a compact design. With its ability to detect a wide range of harmful gases and provide real-time feedback, it is an excellent choice for developers, makers, and engineers building air quality monitoring and safety systems.
Monitor air quality and detect harmful VOCs effectively with the MQ-138 Gas Sensor Module – a reliable, affordable, and versatile solution for clean and safe environments.
