The SparkFun Indoor Air Quality Sensor - SCD41, SEN55 (Qwiic) combines two excellent indoor air quality sensors, the SCD41 and SEN55 from Sensirion^™. These sensors provide a comprehensive indoor air quality sensor that measures CO₂, Volatile Organic Compounds (VOCs), particulate matter (PM1.0, 2.5, 4, and 10), temperature, and relative humidity.

The SCD41 uses Sensirion's PASens® photoacoustic measurement system, which combines narrow-band IR light and a microphone inside the sensing package to detect concentrations from 0 to 40000 ppm with high accuracy over 400-5000 ppm ±(40 ppm+5%). The SCD41 has an integrated temperature and humidity CMOS® sensor to improve accuracy. For additional accuracy, the SCD41 also accepts ambient pressure readings!

The SCD41 includes an automatic self-calibration routine to adjust to its sensing environment over a seven-day calibration period. For best results, Sensirion recommends taking continuous readings for at least one hour a day of 'fresh air' to complete the calibration period. The SCD41 also has a one-shot measurement option for an optimal reduction in power consumption.

The SEN55 environmental sensor node uses Sensirion's proprietary algorithms to provide straightforward integration into various air quality monitoring applications. The sensor measures particulates of the following size specifications: PM1, PM2.5, PM4, and PM10 from a concentration of 0 to 1,000 µg/m³. It also senses both VOC and NO^x indexes from 1 to 500 index points. It offers a robust set of control registers to take and report measurements, check the status of the module and its components, and report them all in easily digestible serial data ove I²C.

The SparkFun Qwiic Indoor Air Quality Combo Sensor takes care of all the pesky power requirements of the SEN55 and SCD41 with onboard DC voltage conversion, allowing a simple, single Qwiic connection for power and communication.

The SparkFun Qwiic Connect System is an ecosystem of I²C sensors, actuators, shields and cables that make prototyping faster and less prone to error. All Qwiic-enabled boards use a common 1mm pitch, 4-pin JST connector. This reduces the amount of required PCB space, and polarized connections mean you can’t hook it up wrong.

SparkFun Indoor Air Quality Sensor Features

• I²C Interface (Qwiic Enabled)
  • 2x Qwiic Connectors
  • 0.1"-spaced PTH header
• AP3012 - 500mA/29V 1.5MHz STEP-UP DC/DC Boost Converter
  • Used for supply voltage to SEN55

SCD41 Features

• I²C Address: 0x62
• Supply Voltage Range: 2.4-5.5V (3.3V Typ.)
• Low Current Consumption:
  • Normal Mode:
    • Max: 205mA@3.3V
    • Typ: 18mA@3.3V
  • Low Power Mode:
    • Typ: 3.5mA@3.3V
  • Single-Shot:
    • 0.5mA@3.3V
• Photoacoustic Measurement System
  • Sensirion's PASens Technology
• Integrated Temperature and Humidity Sensor
  • Sensirion's CMOSens Technology
• CO₂ Output Range: 0-40,000ppm
• CO₂ Measurement Accuracy: ±(40ppm + 5% of reading)
  • Conditions: 400-5,000ppm
• Humidity Range: 0-100%RH
• Humidity Accuracy: ±9%RH (Full Range)
• Temperature Range: -10°C-60°C
• Temperature Accuracy: ±1.5 (Full Range)

SEN55 Features

• I²C Address: 0x69
• Supply Voltage: 4.5V
• Average Supply Current: 63mA
• Max. supply current: 110mA
• Particulate Matter
  • Mass concentration precision: ±10%
  • Mass concentration range: 0 - 1000μg/m³
  • Lifetime: > 10 years
  • Particle size range: PM1.0, PM2.5, PM4 and PM10
• Temperature
  • Typ. temperature accuracy: 0.45°C
  • Operating temperature range: -10 - 50°C
  • Response time(τ63%): < 60s
• Humidity
  • Typ. relative humidity accuracy: 4.5 %RH
  • Operating relative humidity range: 0 - 90 %RH
  • Response time(τ63%): 20s
• VOC
  • Sensor output: 0-500 VOC Index
  • Measurement range: 0 - 1000ppm
  • Response time(τ63%): < 10s
  • Device-to-device var.: ±15% m.v.
  • Limit of detection: < 0.05 ppm of ethanol equivalents or < 10 % of concentration setpoint, whichever is larger
  • Switch-on time: 1h
  • On-chip humidity compensation

• Schematic
• KiCad Files
• Board Dimensions
• Datasheets
  • SCD4x
  • SEN5x
• Hookup Guide
• Qwiic Information Page
• Sensirion Arduino Core Library
• SparkFun SCD4x Arduino Library
• Sensirion SEN5x Arduino Library
• GitHub Hardware Repo