SCD40 Photoacoustic NDIR CO₂ Sensor Breakout Module

A professional-grade carbon dioxide sensor module, compact enough to be nearly coin-sized.

Unlike low-cost “eCO₂” sensors that estimate CO₂ levels based on volatile organic compounds (VOCs), the SCD40 uses advanced photoacoustic non-dispersive infrared (NDIR) technology to physically measure CO₂ molecules. This ready-to-use breakout module includes an onboard voltage regulator and pull-up resistors, allowing you to easily connect it to Arduino, ESP32, or Raspberry Pi projects.

✅ Key Features

• True NDIR CO₂ sensing — no guessing, no chemical degradation
• Ultra-compact design — smaller than a sugar cube
• I2C interface with fixed address: 0x62
• Integrated temperature and humidity sensor
• Automatic Self-Calibration (ASC) — no manual maintenance required
• 5V tolerant / 3.3V–5V power input — breadboard-friendly

📊 Technical Specifications

🛠️ Applications

• Smart thermostats and ventilation control
• Indoor air quality monitoring
• COVID / health-related ventilation and aerosol risk indicators
• Plant grow rooms and terrariums, up to 2,000 ppm
• Portable and battery-powered air quality wearable devices

🔌 Wiring and Installation

Header pins are included but require soldering.

Library: Sensirion I2C SCD4x, available through the Arduino Library Manager.

⚠️ Do not cover the small white filter on top of the silver can — this is the air inlet.

⚙️ Important Notes

Automatic Self-Calibration (ASC) is enabled by default. It assumes that the lowest CO₂ reading over a 7-day period corresponds to fresh air at 400 ppm. Manual calibration is also supported.

Photoacoustic sensing technology uses sound waves. Avoid installing the module near motors, buzzers, or vibrating components.

Designed for indoor use. Outdoor humidity, condensation, or rain may damage the sensor.

For ESP32 projects, 3.3V operation is recommended, even though the module can tolerate 5V power input.

📦 What’s Included

• 1 × SCD40 CO₂ Sensor Breakout Module
• 1 × 4-pin straight header, unsoldered

❓ FAQ

Q: What is the difference between SCD40 and SCD41?
A: The SCD40 supports a measurement range of 400–2,000 ppm. The SCD41 supports measurements up to 5,000 ppm and includes a low-power single-shot measurement mode. This page is for the SCD40.

Q: Is this a bare chip or a module?
A: It is a breakout module — fully assembled with PCB, voltage regulator, and resistors.

Q: Can it measure temperature and humidity?
A: Yes. The built-in SHT4x-class sensor provides accurate temperature and humidity readings.

Q: What is the I2C address?
A: The fixed I2C address is 0x62.

Q: Can I use it with a 5V Arduino?
A: Yes, the module supports 5V power input. For long-term reliability, 3.3V I2C logic levels or a logic level shifter are recommended.

Q: Why do I see small ripples on my power supply?
A: This is normal. The sensor performs internal pulsed measurements, which may cause minor voltage fluctuations on sensitive power rails.

📄 Datasheet and Library

• Sensirion SCD4x Arduino Library, available through the Arduino Library Manager
• Full datasheet available upon request