Digital SGP40 VOC (Volatile Organic Compounds) Gas Sensor for Easy Integration Into Air Treatment Devices and Air Quality Monitors, I2C Bus Compatible with Raspberry Pi/STM32

The packaging was good, no damage at all and works really well. In my opinion, it's very accurate. Especially the temperature as I have things around the house to compare it to. The included connectors makes it so easy to get started, now I want all of my sensors this way! I am very happy with this vendor, Waveshare, I'll buy from them again. They are trustworthy in my opinion and I feel like it was money well spent and not wasted.

The seller contacted me shortly after my review was posted. They apologized and gave me a working link to the page containing full instructions and specifications. Very accommodating customer service. I did get what I paid for!!

This is a decent VOC sensor. It is important to note, however, that you will not get direct measurements of concentrations. The output of the device is a value with little meaning; it is "proportional to the logarithm of the resistance of the MOx material" of the sensor. This means that a big drop in the raw value is associated with a decrease in air quality, but the amount is not intuitive. To this end, Sensirion provides an algorithm for converting the raw output to a "VOC index," which is still not directly associated with a concentration. This index is supposed to be fixed at 100 for the background gas concentration, which varies by environment, and provides a comparison with "the sensor's recent history"; in effect, this sensor can only ever provide relative measures of air quality, not actual concentration-equivalents. This would be useful for, say, detecting an extreme event, but not for accurate monitoring over a long period of time.I do have some concerns about the longevity of the online guide for the software. There are several dependencies that seem to exist on third-party websites that are not affiliated with the sensor's manufacturer. As of June 2023, the instructions do still work, but I fully expect that some of the dependencies will be unavailable or outdated in a few years. Ideally, I'd like to see a description of what the dependencies are used for, and possibly a bundled version with build instructions if the licenses allow for it.

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