AirGradient Forum

Compatibility of formaldehyde sensor (Sensirion SFA40) with AirGradient One Indoor Monitor

Greetings,

Recently purchased a DIY indoor AirGradient One after seeing online reviews and I’m pretty happy with it overall. Easy to assemble etc. (although the bottom stand was a bit tight once it locked in and one stand nearly snapped when I tried to remove it to adjust something inside the case).

Only issue is that one reason for the purchase was to measure formaldehyde (HCHO/CH2O), and unfortunately the product doesn’t seem able to do that at present. However, AirGradient seemed a bit more reputable than run-of-the-mill sensors, and I like the extensibility and open-source support the company and product has.

Looking through some older topics on this, the Sensirion SFA30 sensor was mentioned for measuring formaldehyde, but it seems to have been recently deprecated in favor of their SFA40 sensor. I don’t know much about these circuit boards and the software, but squinting at some pictures of the sensor, it seems to have four pins at the back, just like the VOC sensor the AirGradient One shipped with.

Would anyone happen to know if this sensor can fit into the the current VOC sensor “socket”? And since this measures in ppb rather than the 0-500 index which AirGradient One uses for VOC, would there be any changes in the firmware required?

If it’s plug-and-play or “plug and play and flash some new firmware”, it should be easy enough for me to set up. Anything more complicated than that (e.g. editing code) might be a little challenging, though…

Thanks!

Hi @Quic! We haven’t tested the SFA40 yet but from what I see I don’t think it is compatible with the current version of the AirGradient ONE. We are working on a redesign of the AirGradient ONE and trying to make it more modular so more sensors could be added as needed. I will share this with the engineer we have working on the redesign so this can be taken into consideration.

Thanks a lot for the feedback!