Gravity: SFA40 Formaldehyde (HCHO) Sensor

The DFRobot Gravity: SFA40 Formaldehyde (HCHO) Sensor is a laboratory-grade, highly selective electrochemical gas sensor designed to tackle the biggest issue in indoor air quality monitoring: false alarms. Powered by Sensirion’s cutting-edge SFA40 solid-state electrochemical cell, this compact breakout board precisely tracks trace levels of formaldehyde while ignoring common household interference from cleaning products, alcohol, and perfumes.

Whether you are building a smart HVAC system, engineering an automated air purifier, or creating a DIY wellness monitor, the SFA40 provides stable, calibrated, and highly accurate indoor environmental data.

Key Features

🚫 Zero False Alarms (Anti-Interference Technology)

Traditional gas sensors often spike if someone applies hand sanitizer, peels an orange, or sprays perfume nearby. The SFA40 features unique electrode chemistry that delivers an ethanol cross-sensitivity of less than 0.3%. When your system detects a spike, you can be certain it’s tracking genuine formaldehyde, not background household odors.

🔬 Laboratory-Grade Sensitivity

Formaldehyde can cause respiratory irritation and long-term health risks at incredibly minor thresholds. This module offers a ultra-low detection limit of 20 ppb (parts per billion) across a wide 0 to 1000 ppb measurement range. It effortlessly captures the minor, slow off-gassing emitted by new furniture, wood-based floorings, and paints.

🌡️ On-Board Climate Compensation

Fluctuations in ambient temperature and humidity can alter electrochemical readings. DFRobot has integrated an onboard Sensirion SHT4x sensor alongside the SFA40 element. This automatically applies real-time environmental compensation directly to the HCHO data stream, while also providing individual, highly accurate temperature and humidity outputs to your microcontroller.

🔌 Plug-and-Play Gravity Interface

Equipped with DFRobot’s signature 4-pin Gravity I2C interface, wiring this sensor to development platforms like Arduino, ESP32, or Raspberry Pi takes seconds. It features wide 3.3V to 5V power compatibility and pulls a remarkably low average operating current of just 80 µA, making it ideal for battery-powered or portable monitoring stations.

Technical Specifications

Target Applications

• Smart Home Ventilation: Automatically trigger HVAC exhaust fans or open windows when formaldehyde levels exceed safety limits (typically greater than 80 ppb).

• Intelligent Air Purifiers: Conserve filter life and save energy by engaging heavy-duty VOC/HCHO filtration only when harmful gases are actively detected.

• Health & Safety Dataloggers: Create portable, handheld meters to check air quality inside newly renovated buildings, offices, or new vehicle interiors.

What’s In The Box:

• 1 DFRobot Gravity: SFA40 Formaldehyde (HCHO) Sensor Module

• 1 Gravity 4-Pin I2C/UART Sensor Cable