Combining Adafruit’s CCS811 gas sensor with a Circuit Playground Express and two NeoPixel Sticks we can quickly put together a mask that displays our breath attributes. This setup will monitor temperature, carbon dioxide and total volatile organic compounds. The complete tutorial is available here. The sensor is easy to work with using it’s I2C interface and pre-calibrated ranges. A mask is an ideal wearable as it provides a place to house the electronics as well as an option for continuous monitoring as it is a hands free device that could be adapted for exercise or sleep. The gas sensors TVOC monitoring can be used as an indicator of ketosis as it will detect acetone levels on the breath which is a by-product of producing ketones. CO2 levels can also be a helpful indicator of how much glucose is being burned versus fats.
In this example we are making use of Adafruit’s Circuit Playground Express to connect to the gas sensor and NeoPixel Sticks. This controller is easy to adhere to fabric, program and has ten built-in neopixels which are used to display breath temperature. One NeoPixel stick will show CO2 output (pink) the other will show total volatile organic compounds (blue).
When connecting to the Circuit Playground Express’s Console we can see detailed readings to get an idea of our actual co2, volatile compounds and temperature.
The circuit is minimal and can be assembled using Adafruit 1/4 size perma proto board. A li-poly battery can be used to power this circuit through the JST connector or a micro USB cable can be connected to a USB power source. The Circuit Python code is available here. Full tutorial here.