Laerke.Eu: An Online Pressure Sensor System for Monitoring Gas Consumption and Formation in Vials

Lærke is a pressure sensor system developed by DTU Biosustain in collaboration with FabLab RUC, designed for real-time, non-invasive monitoring of pressure changes in vial experiments.<br/><br/>It provides continuous online data acquisition, enabling high-frequency measurements without the disturbances, leakage, and contamination risks associated with manual sampling methods, especially critical in anaerobic microbial studies. The system facilitates detailed, high-resolution analyses of gas production and consumption in biological and chemical processes. Specifically suited for studies on microbial consumption of syngas, H₂/CO₂, methane production, and CO₂ formation during fermentation by yeast or other microorganisms, Lærke can be integrated with online optical density (OD) measurements. This provides insights into the relationship between biomass growth and gas dynamics in small-scale vial setups, indicating shifts between liquid or gas metabolism.<br/><br/>Each Lærke unit comprises a Wi-Fi-enabled microprocessor connected to a number of precision pressure sensors on a custom-designed printed circuit board (PCB), each fitted with sterile, replaceable needles. Pressure data is sampled and stored locally, accessible via Wi-Fi, or transmitted to a server for immediate visualization and analysis. The system operates within a pressure range of 0–30 bar, with a resolution of 0.2 mbar. All collected data is stored in CSV format for post-experiment manual analysis. We have applied the system to measure syngas and H₂/CO₂ consumption rates, yeast and other CO₂-producing fermentations, as well as biogas production rates.<br/><br/>Lærke provides a high-resolution, cost-effective solution for gas kinetics, lag phases, and closing carbon balances in small-scale vial-based experiments. It serves as an affordable, simple, and robust alternative to larger bioreactors equipped with online mass spectrometry.<br/><br/>This work is part of the Fermentation-Based Biomanufacturing initiative (FBM), funded by the Novo Nordisk Foundation (grant number: NNF17SA0031362).