Formaldehyde sensor: SFA30
Formaldehyde sensing made easy
Formaldehyde is a commonly encountered indoor pollutant that can have long-term negative health effects even at concentrations as low as 0.000008 %. The SFA30, Sensirion’s digital formaldehyde sensor, offers best-in-class detection of this substance and can be easily integrated into air purifiers, demand-controlled ventilation systems and indoor air-quality monitors.
Based on Sensirion’s electrochemical technology, the sensor is tailored to sense levels of formaldehyde in the parts-per-billion (ppb) region, which is important to human health, and has a unique output accuracy when exposed to omnipresent volatile organic compounds (VOCs). The sensor has excellent long-term stability and durability, in addition to its ability to give accurate humidity and temperature readings, which combine to produce a fully temperature/humidity-compensated and factory-calibrated formaldehyde concentration output. Moreover, as with other Sensirion environmental sensors, its selectable digital UART and I2C interface options, standard electrical connector and versatile mounting options enable easy integration into the final device.
Key benefits of Sensirion’s formaldehyde technology
1. Relevant range
Formaldehyde is a frequently encountered indoor pollutant due to numerous common sources of the chemical inside buildings, such as off-gassing from plywood furnishings and flooring, burning candles, cooking on a gas stove and smoking. According to the WHO, long-term exposure to formaldehyde concentrations as low as 10s of ppb can lead to adverse health effects, such as respiratory system irritations, chest pains and bronchitis. Therefore, the WHO limit for 30-minute average formaldehyde exposure is set to 80 ppb. Knowing the indoor formaldehyde concentration is the first step towards reducing exposure below the recommended levels. However, until now, monitoring these low concentrations has been a challenge: Traditional precise measuring methods require local sampling and remote analysis in a specialized laboratory instrument, while online monitors based on traditional electrochemical sensors suffer from their cross-sensitivity to other VOCs, making reliable formaldehyde measurements in the ppb range difficult.
To overcome this, Sensirion’s formaldehyde technology is optimized for low concentration detection in the ppb range, even in the most challenging household environments. The sensors are able to compensate for variations in temperature and relative humidity and uniquely retain the formaldehyde-specific signal output despite the presence of other typical household volatile organic compounds, e.g., ethanol.
2. Avoiding false positives
Typical causes of false-positive sensor readings include a large offset in the absence of formaldehyde, as well as high cross-sensitivity to volatile organic compounds and signal variability due to environmental conditions. These trigger air purifiers to work even in the absence of formaldehyde or when insignificant formaldehyde concentrations are present, reducing the lifespan of the devices. Sensirion’s formaldehyde sensor is equipped with an integrated relative humidity sensor and a specially designed algorithm to compensate for the environmental effects, e.g. temperature and relative humidity. Moreover, its unique design ensures excellent selectivity to formaldehyde even in the presence of other gasses, such as ethanol.
According to the Council of Gas Detection and Environmental Monitoring (CoGDEM), three key processes limit the lifetime of electrochemical sensors: catalyst degradation, electrolyte leakage and electrolyte evaporation. Indeed, liquid electrolytes are particularly susceptible to evaporation or drying out at high temperatures and in dry ambient conditions. In contrast, Sensirion’s anti-dry technology ensures long-lasting sensor stability with a six-year Lifetime.
Features and applications
|Name||Sensor output||Formaldehyde accuracy||Supply voltage range||Interface||Size (LxWxH) mm||Datasheet||Buy|
|SFA30||Formaldehyde concentration in ppb,|
Relative humidity in %,
Temperature in °C
|±20 ppb or ±20% of measured value,|
whichever is larger
|3.3 V or 5.0 V (3.15 - 5.5 V)||I2C / UART||46 x 24 x 5.5 mm3||Download|
Technology and benefits
|Electrochemical cell with anti-dry technology||Excellent long-term stability and six-year service lifetime|
|Integrated SHT humidity and temperature sensor||On-board RH and T compensation, additional RH and T output|
|Uniquely low cross-sensitivity to other VOCs||Reliable Formaldehyde measurements in real-life conditions|
|Fully factory-calibrated module||Easy to use and life-time calibrated|
Start evaluating the SFA30 today
The SEK-SFA30 evaluation kit has been designed to easily evaluate the performance of Sensirion’s SFA30 formaldehyde sensor. In addition to the SFA30 sensor module, the SEK-SFA30 comes with a UART-USB cable for a plug-and-play connection to a PC and evaluation of the sensor using Sensirion’s easy-to-use SEK-ControlCenter viewer software. A seven-pin jumper wire cable is also provided to connect the sensor to prototyping platforms such as Arduino or RaspberryPi.
More information (documentation, drivers, tutorials, etc.) can be found here:
Compile your own environmental sensing evaluation kit at: www.sensirion.com/sek