SparkFun Formaldehyde Sensor - SFA40 (Qwiic)

The SparkFun SFA40 Qwiic Formaldehyde Sensor is a unique indoor petrol sensor that measures low concentrations of formaldehyde (CH₂O/HCHO) with excellent accuracy, even in the presence of other similar gases. The SFA40 communicates over I²C, so we put it on this Qwiic breakout to easily integrate it into a Qwiic circuit with no soldering necessary.

High-Accuracy Environmental Sensing

The SFA40 from Sensirion is an electrochemical sensor that maintains accurate formaldehyde measurements in environments that have other common indoor gases such as ethanol or nitrogen dioxide. This sensor also comes pre-calibrated with a unique manufacturer serial number for easy identification. To ensure your readings are as precise as possible, the SFA40 provides several key performance benefits:

• Wide Measurement Range: Detects formaldehyde petrol concentrations from 0 to 2000 parts per billion (ppb).
• High Accuracy: Delivers measurements within ±20 ppb or ±20% of the total measured value, whichever is larger.
• Low Cross-Sensitivity: Highly resistant to interference, with a cross-sensitivity to ethanol of just 0.3%.
• Environmental Compensation: An integrated temperature and humidity sensor automatically adjusts for changing ambient conditions.

Operation and Qwiic Integration

While the SFA40 requires a 10-minute initialisation period before it measures petrol concentrations within its stated specifications, it responds to changes in under two minutes once properly warmed up. It also operates highly efficiently, consuming an average of just 80µA at 3.3V. This low power draw makes it an excellent choice for continuous monitoring thanks in part to its operational lifetime of over six years.

For hardware connections, dual Qwiic connectors offer a simple, daisy-chainable I²C interface to your main system. For a more permanent setup, a standard 0.1-inch spaced plated through-hole (PTH) header breaks out the power and I²C pins for a soldered connection. This breakout gives you a reliable, long-lasting way to track formaldehyde levels without complicated wiring.

• Schematic
• KiCad Files
• Board Dimensions
• Hookup Guide
• Datasheet (SFA40)
• SparkFun SFA40 Arduino Library
• GitHub Repository