Mike Rankin's Desktop Air Quality Monitor Packs a Square PCB Into a Round Housing

Housed in a 3D-printed chassis with plenty of room for expansion, this desktop air quality sensor makes the most of a small footprint.

Maker Mike Rankin has put together an air quality monitor with a difference: its custom-designed 3D-printed housing uses a round display, rather than the more usual rectangular format, to show total volatile organic compounds (TVOC) and carbon dioxide concentration, temperature, and humidity data.

"This project is an Arduino[-compatible Espressif] ESP32 based CO₂ sensor using a 1.28" round display," Rankin writes of the neat desktop gadget. "So far I've used OLED and TFT displays in square and rectangular shapes so this was an excuse to try a round one. I see this as an evolving project since the capacitive touch display is not used and there is plenty of room in the enclosure for other items."

That enclosure is a 3D-printed housing designed specifically for the project. A custom-designed controller board with an Espressif ESP32 Pico-D4 chip at its heart sits at the bottom, with access to the USB Type-C port for power and programming provided via a cutout in the case, while the 1.28" color display is mounted at the front.

"The 3D-printed enclosure is a friction fit with one screw holding the board in place," Rankin notes of the housing's design and assembly. "A fair amount of pressure is need to insert and remove the USB connector so this should help keep everything in place."

The board itself includes a chip antenna for wireless connectivity from the ESP32's integrated radio, a Texas Instruments HDC1080DMBT temperature and humidity sensor, and a Sensirion SGP30 air quality sensor capable of reading total volatile organic compound (TVOC) and equivalent carbon dioxide (eCO₂) concentration.

Design files and source code for both the board and enclosure are available on Rankin's GitHub repository under an unspecified open source license.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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