In order to keep his 3D printing filaments from degrading, Dr. Scott M. Baker purchased a number of PrintDry containers off of Amazon. While expensive, they seal so tightly that they can pull a small vacuum, ensuring that moisture doesn’t enter your storage container, and the desiccant used to keep things dry can do its job. Unfortunately, he found that while most can maintain a vacuum with a little bit of work, many lose vacuum quickly without a little attention.
Not satisfied with his filament only possibly being protected, Dr. Baker got to work creating a humidity, pressure, and temperature monitor for each of his sealed canisters. His first prototype featured an ePaper display, but between the limits of the ATmega328 microcontroller that he was using, power concerns, and a relatively high price per unit, he decided to rethink things and go wireless.
His final design employs a BME280 sensor, an ATtiny85 for processing, and an SYN115 module for RF data transmission. Info is received by a Raspberry Pi 4 via an RTL-SDR dongle, allowing him to track each filament container individually on a Prometheus database, then display it on a Grafana GUI .
This even lets him detect when a certain filament container was opened based on vacuum levels, or compare the performance of vacuum sealed containers versus normal containers without a vacuum applied. Code for the build is available on GitHub, and a detailed explanation is found in the video below.