The sourdough bread craze from the start of the pandemic lockdowns has led to a lot of delicious crusty loaves, but also this ingenious device: a peanut butter jar equipped with a Raspberry Pi and e-ink screen, that measures the CO2 levels of your sourdough starter - or indeed anything that ferments in a jar - to let you know when it's just right for baking.
The brainchild of artist and maker Noah Feehan, who blogs at hi-hi-hi.com, the e-Ink Starter Monitor displays the last three hours of CO2 production, and how much the sourdough has risen by in the same time period, and is the result of two years of bubbly-dough observation and experimentation.
Entirely built into the lid of the fermentation jar, the assembly uses a fan to pull a constant stream of air from within the jar past its CO2 sensor - an Adafruit SCD-30 - while the height of the sourdough in the jar is measured using an Adafruit VL6180X Time of Flight Distance Ranging Sensor, both connected to a custom PCB (sadly a surfboard rather than the more appropriate breadboard). The CO2 sensor also measures temperature, which Feehan uses to tell whether the jar has been put in the fridge - turning off the Wi-Fi if it has to preserve battery power. The LilyGo e-ink screen displays CO2 levels and starter height for the last three hours, its built-in ESP32 Wi-Fi and Bluetooth module taking care of wireless communication.
For more fine-grained statistics, the jar can pass its data to a Raspberry Pi Zero W over the MQTT (Message Queuing Telemetry Transport) protocol, which can also log the data for more than three hours to pick up longer-term trends.
Feehan hints in his post that he’s doing work on zero-g fermentation with MIT, so this could be just the first step toward delicious, tangy sourdough being produced in space.
Visit our list of Best Raspberry Pi Projects for more cool creations from the Pi community.