Cattle methane causes 18% of current global warming. CowBell Labs is creating a wearable “nose ring” device for monitoring methane from cow breath. Such a device will enable accurate reporting of methane emissions from cows in their normal environment, supporting data-driven abatement interventions.
CowBell Labs contracted Mosaic Design Labs to develop a product design concept for a battery-powered wearable device and evaluate a range of commercial methane and CO2 sensors that could be used in such a device.
As part of this work, Mosaic built a portable, briefcase-style instrument that could be deployed to dairy farms to collect measurements of cow breath emissions and evaluate design parameters for a wearable device. This briefcase system included a gas sampling intake pump and mass flow controller connected in series with an array of gas sensors (compact NDIR CH4/CO2 sensor, temperature/humidity/pressure sensors, and a gold-standard TDLAS CH4 sensor).
The system was designed with flexibility in mind so that sensors could easily be swapped in and out as different options were evaluated. The entire system was battery powered and build around a Raspberry Pi with a Touchscreen UI. All software was developed in Python. Data recording could be initiated from the touchscreen, which also provided a live graph of CH4/CO2 concentration. With a built-in Wifi router, researchers could easily log into the briefcase with a laptop and access a Jupyter Lab server which included pre-built scripts for data analysis and visualization. The software was developed in Python with an HTML5 frontend using Eel, an efficient stack for rapid embedded UI development.
The team also built a custom test chamber which delivered controlled amounts of gasses via mass flow controllers. We characterized seven different CH4 and three different CO2 sensors using this system, comparing different classes of sensor technologies (NDIR, Pellistor, Electrochemical, Chemiresistive, and MEMS). The team also developed a wearable halter for breath sampling and successfully recorded methane emissions from live dairy cows.
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