MQ138 Formaldehyde Sensor Breakout with Qwiic

The MQ138 Formaldehyde Sensor Breakout detects formaldehyde and other volatile organic compounds (VOCs) over a convenient Qwiic connection.

Protect your place from dangerous organic compounds with the MQ138 Formaldehyde Sensor. Formaldehyde, benzene, toluene, and acetone are invisible health hazards commonly found in new furniture, building materials, paints, and cleaning products - but now you can detect them before they become a problem.

Perfect for indoor air quality monitoring, smart home safety systems, and industrial hygiene applications, this intelligent sensor features an onboard microcontroller for accurate, calibrated readings through the convenient Qwiic interface. Engineered with an integrated microcontroller, this sensor delivers pre-calibrated readings through the Qwiic interface, eliminating analogue signal processing and calibration requirements.

Please note that you will have to use our Arduino library for the project to ensure correct communication with the onboard microcontroller. Don't worry, using our documentation, you should find it easy to get started.

The digital output provides reliable, consistent measurements while the Qwiic system enables tool-free connection to all Soldered development boards and others which support the Qwiic/STEMMA-QT interface. The 3.3V operation with onboard regulation ensures compatibility with modern microcontroller systems, while four mounting holes enable secure installation in monitoring applications.

This sensor is ideal for detecting formaldehyde levels in new homes, furniture, and workplace safety monitoring. The LED indicator provides immediate visual feedback when harmful VOC levels are detected. Allow an initial heat-up period (48 hours first run and then each consecutive run 5 mins heat up time) for optimal accuracy.

The sensor provides relative concentration readings perfect for trend monitoring and threshold detection. Ideal for triggering ventilation systems or safety alerts. Four mounting holes enable permanent installation in HVAC systems, indoor air quality monitors, or portable testing devices. Compatible with Arduino, Raspberry Pi, and ESP32 through the Qwiic interface.

Includes documentation and example code for immediate implementation in air quality monitoring projects. Custom selectable I2C address via onboard switch ensures compatibility with existing projects.

View our full range of Soldered Electronics products here.

Features

• Detects formaldehyde, benzene, toluene, and acetone
• Integrated onboard microcontroller with pre-calibrated readings
• Qwiic interface for tool-free connection
• Digital output with LED indicator for VOC level feedback
• 3.3V operation with onboard regulation
• Compatible with Arduino, Raspberry Pi, and ESP32
• Selectable I2C address via onboard switch
• Four mounting holes for secure installation
• Provides relative concentration readings for trend monitoring
• 5-minute heat-up time per operation (48 hours for initial use)
• Includes documentation and example code
• Ideal for indoor air quality monitoring and smart home safety
• ATTiny404 microcontroller onboard
• Qwiic connectors

Specifications

• Dimensions: 54 x 22mm

Resources

• Full product documentation
• Pinout drawing
• Hardware details
• Arduino library documentation
• Open source hardware files
• Getting started with Arduino
• Arduino library

Package Contents

• 1x Benzene, Toluene, Acetone, Formaldehyde Sensor MQ138 Breakout with Qwiic