Sensirion SFA30 & SFA40: Advanced Formaldehyde Sensors for Indoor Air Quality
Making formaldehyde detection easy with highly selective and stable electrochemical sensors.
Introduction to Formaldehyde
Formaldehyde is a common indoor pollutant found in wooden furniture, flooring, paints, and cosmetics. It acts as an irritant to the respiratory system and a potential carcinogen, posing health risks even at very low concentrations. Sensirion has developed the SFA30 and SFA40 sensors to address the challenge of detecting these low levels of formaldehyde, offering high sensitivity and selectivity that accurately identify formaldehyde even in the presence of other volatile organic compounds (VOCs).
Sensirion's in-house calibration and testing infrastructure ensures an efficient process. Each sensor is individually calibrated and tested at their Swiss headquarters, guaranteeing quality and precision.
Principle of Electrochemical Measurement
Sensirion's formaldehyde sensors utilize an amperometric electrochemical measurement principle, achieving minimal cross-sensitivity and excellent long-term stability. Formaldehyde is decomposed at the working electrode, generating a current flow between the working and counter electrodes, which is proportional to the formaldehyde concentration. Through Sensirion's unique chemical properties, the sensor selectively detects only formaldehyde, distinguishing it from other VOCs.
An electrochemical cell diagram illustrating the measurement principle. It features a membrane, a working electrode, electrolyte, and a counter electrode. Formaldehyde (HCHO) enters the cell. Within the electrolyte, it reacts, producing carbon dioxide (CO2) and water (H2O). The process involves the movement of ions and electrons, indicated by + symbols, generating a measurable current flow [current-flow] which is proportional to the formaldehyde concentration.
SFA30 Formaldehyde Sensor
The SFA30 is a digital formaldehyde sensor that meets requirements set by WHO, GB/T, WELL, and ASHRAE standards, enabling easy integration. Based on electrochemical measurement, the SFA30 exhibits very low cross-sensitivity to other VOCs such as ethanol. The integrated temperature and humidity sensor allows for on-chip signal compensation. The patented dry-electrode technology effectively overcomes the limitations of liquid electrolyte evaporation, ensuring superior stability and a lifespan of over 6 years.
Features
- Patented dry-electrode technology with excellent long-term stability and a lifespan of 6+ years.
- Integrated temperature/humidity sensor for compensation (temperature/humidity output also available).
- Low cross-sensitivity to other VOCs.
- Factory-calibrated module for ease of use and reliable formaldehyde measurement under real-world conditions.
Applications
- Air purifiers
- Indoor air quality monitors
- Air conditioners
SFA30 Evaluation Kit (SEK-SFA30)
The evaluation kit includes:
- SPS30 × 1 unit
- UART-USB adapter cable (2m) × 1 piece
- Jumper wire set × 1 set
SFA40 Formaldehyde Sensor
The SFA40 is the world's smallest electrochemical formaldehyde sensor, measuring just 10 × 13 × 2.4 mm³. This compact size opens up new possibilities for applications. The sensor, built upon an integrated electrochemical cell and a dedicated ASIC, offers a digital output with outstanding selectivity and accuracy. Its exceptionally low power consumption makes it ideal for seamless integration into air purifiers, indoor air quality monitors, and air conditioners.
Features
- 10 × 13 × 2.4 mm³ small footprint, enabling space-efficient design-ins.
- Ultra-low power consumption of 80 µA (lower modes are under development).
- Patented dry-electrode technology with excellent long-term stability.
- Low cross-sensitivity to other VOCs for reliable formaldehyde measurement under real-world conditions.
- Factory-calibrated module for ease of use and calibration throughout its lifespan.
Applications
- Air purifiers
- Indoor air quality monitors
- Compact, portable, non-rechargeable battery-powered formaldehyde monitors
- Air conditioners
Technical Specifications
| Parameter | SFA30 | SFA40 |
|---|---|---|
| Measurement Range (ppb) | 0 ~ 1000 | 0 ~ 1000 |
| Size | 46 × 24 × 5.5 mm³ | 13 × 10 × 2.4 mm³ |
| Sensor Output | Formaldehyde Concentration (ppb, RH, T) | Formaldehyde Concentration (ppb) |
| Ethanol Cross-Sensitivity | < 0.5% | < 0.3% |
| Detection Limit (ppb) | < 20 | < 20 |
| Lifespan | 6+ years | (Implied similar, not explicitly stated for SFA40 in this row) |
| Supply Voltage | 3.15 ~ 5.5 V | 1.62 ~ 3.6 V |
| Supply Current (Avg) | 1000 µA | 80 µA @ 2 Hz |
| Supply Current (Max) | 5 mA | 2 mA |
| Interface | I2C, UART | I2C |
| IAQ Standards Compliance | GB/T, WELL, ASHRAE, WHO | GB/T, WELL, ASHRAE, WHO |
| Standard Accuracy (% RH) | 2.5 | N/A |
| Operating Range (% RH) | 10 ~ 90 | N/A |
| Operating Temperature (°C) | 0.2 | N/A |
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