Ikea VINDRIKTNING Air quality sensor HOW IT WORKS 

i'm a bit late, but the infrared led could be a ambiant light sensor, i have the same model at home, and the brightness of the leds adjust automatically to the brighness of the room. not sur why your unit wasn't doing it tho

I always wondering how the brightness of the indicator change. Thanks for your tear down, that infrared sensors work just as the light sensor in our phone, but it won’t change for your room light but the sun light! You can hit that sensor with a remoter to see it change brightness

6:14 Air quality numbers are in μg/m³. So 0-35 means 0 μg/m³ - 35 μg/m³

tnx

Hack it 👍 it's already been connected to esp32 by others...

Hahahahahahhahaha! Cannot blame you for you may not be familiar how that really works. I was yelling in my head "WHY!". HAHAHAHAHAHAHAH! I thought you knew how it works since you are into electronics and it is an electronics part. 1) The said "soot" is not soot. It is vaporised wax. It settles on surfaces, hence the sensor is fundamentally stuck with solidified/condensed wax. The sensor could have been permanently blocked with that wax. Vaporised wax is rather heavy, it cannot stay suspended in the air for that long relative to that smoke from a match. 2) That LED thing makes up the opto-sensor thing identical to that in mouse and in anything which needs counting. It is also used to measure bacterial growth or spores by optical density.