Airvalent CO2 monitors.

https://airvalent.com/

Exciting to see how small these are getting, similar size to apple airpods case. Looking forward to seeing this tech ~1-3 versions from now, where air quality monitoring can just be part of a smartwatch.

The sensor itself is quite small (but not yet flat enough to be in a watch...), the bulk of it is the controller board/bluetooth/screen/battery.

Could probably do a small keychain thing though.

Good read: https://forum.breathesafeair.com/t/photoacoustic-co2-sensor-accuracy-scd40-scd41/20/

Sounds like they lose some effectiveness as temperature changes (vs the Aranet4 sensor), and I bet as elevation changes too (since they rely on pressure in a chamber).

A doodler and computerer. I like permissive/permissionless open source, smart contracts, p2p systems, room-scale VR, and NixOS.

shazow.net

Currently: WhatsABI

The sensor itself, if anyone is curious: https://sensirion.com/products/catalog/SCD41

The Aranet4 sensor for comparison: https://senseair.com/product/sunrise/