This Air Quality Monitor Plugs Directly Into Wall Outlets

Mike Rankin built this handy CO2 level monitor with a very cool feature: the ability to plug directly into wall wart USB chargers.

If your home is anything like mine, then every available horizontal surface has one or two devices resting on it. That leaves little room for setting down car keys or chopping carrots. But I’m willing to bet that your walls have plenty of free space around shin level where the electrical outlets reside. Wouldn’t it be nice if your devices could live there? This compact air quality monitor designed by Mike Rankin can, thanks to its cable-free male USB-C plug.

This device’s purpose is to monitor, record, and communicate indoor CO2 levels. It displays that information on a nice little screen, along with a graph of recent data to show spikes and other anomalies. And as an IoT (Internet of Things) device with a built-in Wi-Fi adapter, it can send its collected data over the local network to the cloud for storage and more robust analysis.

But this device’s best feature is the male USB-C plug mounted at a right-angle on the back of the PCB. That lets the user plug the device directly into a standard wall wart USB charger—no cable necessary. It can monitor CO2 levels while it remains out of the way near the ground, instead of taking up valuable horizontal surface real estate.

In addition to the display, that PCB contains two important components: an ESP32-S3 microcontroller and the CO2 sensor. That sensor also mounts at a right angle, which lets it sit next to the wall charger to keep the entire package as compact as possible. A few buttons let the user interact with the device.

This is a pretty niche device that few people need, but Rankin’s design is very appealing and the USB plug attachment style would work well on many other types of devices.

Cameron Coward
Writer for Hackster News. Proud husband and dog dad. Maker and serial hobbyist.
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