The MQ-7 Gas Sensor Module is a semiconductor-based gas detection module specifically designed to detect carbon monoxide (CO) gas. It is widely used in gas leakage alarms, safety systems, air quality monitoring, and educational electronics projects. The sensor operates using a heated tin dioxide (SnO₂) sensing element whose resistance changes in the presence of carbon monoxide, enabling reliable detection when properly calibrated.
Core Sensor Specifications
• Sensor Type: Semiconductor gas sensor
• Sensor Model: MQ-7
• Target Gas: Carbon Monoxide (CO)
• Detection Principle: Resistance variation due to gas concentration
Electrical & Interface
• Operating Voltage: 5 V DC
• Heater Requirement: Cyclic heating (high and low temperature phases)
• Output Type: Analog and Digital (module dependent)
• Interface Pins: VCC, GND, AO, DO
• Sensitivity Control: Onboard potentiometer for digital output threshold
Performance Characteristics
• High sensitivity to carbon monoxide
• Good selectivity compared to other MQ sensors
• Stable output after proper warm-up and cycling
• Suitable for continuous safety monitoring
Physical Characteristics
• Module Type: PCB-mounted gas sensor module
• Sensor Element: SnO₂ metal oxide semiconductor
• Protective Cover: Stainless steel mesh cap
• Compact and durable construction
Compatibility
• Arduino Uno / Nano / Mega
• ESP8266 / ESP32
• Raspberry Pi (with external ADC)
• Gas alarm and safety systems
• IoT-based air quality monitoring devices
Key Advantages
• Optimized for carbon monoxide detection
• Simple analog and digital interfacing
• Widely available and cost-effective
• Suitable for safety and educational applications
Technical Insights
• Requires alternating heater voltage for accurate CO detection
• Initial burn-in time improves sensor stability
• Analog output recommended for precise measurement
• Affected by temperature and humidity variations
Applications
• Carbon monoxide detectors
• Gas leakage and safety alarms
• Industrial safety systems
• Air quality monitoring
• DIY and educational electronics projects
Pro Tip
• Follow recommended heater cycling method
• Allow sufficient preheating before readings
• Calibrate using known CO levels if accuracy is critical
• Use averaging to reduce noise in analog readings
Package Includes
• 1 × MQ-7 Gas Sensor Module