We have been testing it. It is based on SGP41, a VOC sensor, but it removes the absolute VOC value, as the manufacturer believes this value is not very meaningful because VOC represents dozens of possible combinations.
For the VOC index, 100 is used as the standard. If it exceeds 100, the air quality is considered poor. This value is relative, based on a baseline of approximately the past 24 hours, calculated by an algorithm. Therefore, its value is always an index.
It acts like a nose, sensing when something is off in the air. However, an increase in the VOC index does not necessarily mean something is wrong; it simply indicates that there are different substances in the air.This means that even eating roast duck could cause it to rise rapidly. We invite you to explore its possibilities with us.
Since temperature and humidity significantly affect VOC calculations by the sensor, we added a set of SHT30 temperature and humidity sensors to compensate for the SGP41. The image shows the difference between compensated and uncompensated readings, which appear somewhat different.
Please note that these temperatures may be inaccurate due to the high heat generated by the ESP32. However, based on our understanding of the SCD40, this should not have a significant impact on sensor calculations.
There are some excellent articles explaining its uses: