The SCD-40 breakout is perfect for indoor/outdoor air quality and CO2 measurements. It has a range of 400~2000 ppm with an accuracy of +-(50 ppm + 5% of reading). The SCD-40 is a photoacoustic true CO2 sensor that will tell you the CO2 PPM (parts-per-million) composition of ambient air. This sensor can run from 3.3 to 5V but it’s more important for it to have a quiet power supply with low ripple, than any particular voltage. For that reason we’ve added a 3.3V regulator and level shifters: when connecting to a 5V microcontroller like an Arduino UNO the 5V supply is often shared with other electronic components that add noise. The onboard regulator will keep the voltage nice and quiet. For advanced hackers, they can cut/solder the back traces to change whether the regulator is enabled and what I2C logic level is desired.
SCD-40 Specifications

Photoacoustic CO2 sensor technology

Integrated temperature and humidity sensor

Measurement range: 400 ppm 2000 ppm

Accuracy: +-(50 ppm + 5 % of reading)

Current consumption: 17 mA (meas. rate = 5 s) / 0.5 mA (meas. rate = 5 min)

Fully calibrated and linearized

I2C digital interface address 0x61

Dimensions: 25.5mm x 22.8mm x 7.7mm
Weight: 2.8g

STEMMA QT / Qwiic 4-pin 1mm Pitch White Female Connector Cable 150mm Long – Both Sidecan be purchased seperately.
Resources
User guide

FAQs:

Q: What is the measurement range of the SCD-40 for CO2?
A: The SCD-40 can measure CO2 concentrations in the range of 400 to 2,000 ppm (parts per million).
Q: How accurate is the SCD-40 in measuring CO2, temperature, and humidity?
A: The sensor boasts high accuracy, with CO2 readings within (30 ppm + 3%), temperature readings within 0.2C, and humidity readings within 2% RH.
Q: What communication interface does the SCD-40 use?
A: The SCD-40 communicates via I2C, a common communication protocol used in many electronic devices.
Q: Is the SCD-40 suitable for outdoor use?
A: While the sensor can measure a wide range of environmental conditions, it’s designed for indoor use. The optimal operating range is 0 to 50C and 0 to 95% relative humidity.
Q: What applications can I use the SCD-40 for?
A: The SCD-40 is ideal for a variety of applications where accurate CO2, temperature, and humidity readings are needed. Some examples include:

Indoor air quality monitoring
HVAC systems
Smart home devices
Building automation
Agricultural and industrial monitoring