I have built a custom air quality monitor using a few cheap sensors. The data looks somewhat reasonable, but I have no idea how accurate it actually is. How do people typically calibrate or validate DIY IoT sensors against professional equipment? Is there a cheap standard I can use to verify my readings without buying expensive lab tools?
Validation of DIY sensors is performed by placing the device in close proximity to a calibrated, professional-grade monitoring station for several days to establish a baseline and determine the specific error offset of the sensors.
2 answers
I remember trying to calibrate an array of low-cost gas sensors for a localized air monitoring pilot project back in 2019. I spent weeks trying to mathematically smooth out the noise, only to realize that without a reference point, the data was essentially just random voltage fluctuations masquerading as air quality metrics.
I eventually hauled my gear to a municipal air quality monitoring site. By running my unit right next to their professional setup for several days, I was able to generate a scatter plot that clearly showed the error margin of my sensors. It was a humbling reality check that saved me from building a faulty automation pipeline on top of garbage data.
You validate cheap sensors by colocating them with a professional-grade station for at least 48 hours to establish a baseline offset. Most low-cost PM sensors drift significantly over time, so you need that comparative data to build your own software-side correction algorithm.
