The MQ-3 Gas Sensor Module is a semiconductor-based alcohol detection sensor designed to sense ethanol vapors in the air. It is commonly used in breath analyzers, alcohol detection systems, safety devices, and educational electronics projects. The sensor works by changing its internal resistance when exposed to alcohol gas, providing both analog and digital outputs for flexible integration with microcontrollers.
Core Sensor Specifications
• Sensor Type: Semiconductor alcohol gas sensor
• Sensor Model: MQ-3
• Target Gas: Alcohol (ethanol)
• Detection Principle: Change in resistance due to gas concentration
Electrical & Interface
• Operating Voltage: 5 V DC
• Heater Voltage: 5 V DC
• Output Type: Analog and Digital (module dependent)
• Interface Pins: VCC, GND, AO, DO
• Sensitivity Control: Onboard potentiometer for digital threshold
Performance Characteristics
• High sensitivity to alcohol vapors
• Fast response after warm-up
• Stable output for continuous monitoring
• Requires calibration for consistent readings
Physical Characteristics
• Module Type: PCB-mounted gas sensor module
• Sensor Element: SnO₂ metal oxide semiconductor
• Protective Cap: Stainless steel mesh
• Compact and durable design
Compatibility
• Arduino Uno / Nano / Mega
• ESP8266 / ESP32
• Raspberry Pi (with ADC)
• Breath analyzer systems
• Embedded safety and monitoring devices
Key Advantages
• Specifically tuned for alcohol detection
• Simple analog and digital interfacing
• Widely used and well documented
• Cost-effective sensing solution
Technical Insights
• Requires preheating time before stable operation
• Readings affected by temperature and humidity
• Analog output preferred for concentration estimation
• Not selective for specific alcohol types beyond ethanol
Applications
• Breath alcohol testers
• Drunk-driving detection systems
• Industrial alcohol monitoring
• Safety and alert systems
• Educational and DIY electronics projects
Pro Tip
• Allow sufficient burn-in time for accurate sensing
• Calibrate using known alcohol concentration
• Use analog output for better resolution
• Avoid exposure to corrosive gases
Package Includes
• 1 × MQ-3 Gas Sensor Module