Integration of pH Sensing in Open-Source Bioreactor

Integration of pH Sensing in Open-Source Bioreactor

Abstrakt

Current cultivation of microorganisms utilizes modern, semi-automated platforms with various sensors monitoring the whole process. One of the examples is Chi.Bio, an open-source bioreactor, originally developed as a small and affordable platform for in situ cultivation [1]. Unfortunately, its measuring capacity is limited to mostly optical and thermal sensors. Some of the basic and useful parameters, including pH, are not available in commercially available setup. In our study, we expanded Chi.Bio’s capacity for a pH measurement allowing continuous monitoring with a commonly available pH probe. Our approach builds on recently published work by Denton et al. (2024) [2]. However, we introduced numerous hardware and software modificat ions to both, the original Chi.Bio system and the augmentation by Denton et al. The project began as a breadboard prototype that combined the original bioreactor hardware with an Atlas Scientific Embedded pH Circuit, an Arduino Nano, and a Mikroe pH Click board. This basic hardware setup was used to develop and improve the software components, implemented in Python, HTML, and JavaScript. The final assembly, however, eliminated the need for any additional microcontroller, and the integration of a voltage transformer reduced the pH-electrode hardware to a compact 5 × 5 cm low-cost module with a single connection cable to the bioreactor. The resulting setup was tested in a simple two-day in vitro experiment based on E. coli cultivation, evaluating the relationship between sample optical density (used as a proxy for cell number) and externally modified pH achieved by gradual additions of 30% NaOH. During the experiment, five additions of lye were performed (10, 20, 30, 80, and 200 μL). Each addition resulted in a stepwise pH increase accompanied by a moderate decrease in optical density. Results showed that the pH module can be reliably used for experimental purposes. It provides stable readings, is easy to handle, and allows straightforward retrieval of pH data directly from the data table after the experiment. Thus, our custom-made Chi.Bio platform now supports real-time pH monitoring in a small-scale, low-cost setup, and represents a perfect platform to integrate additional sensors in our future work.

Current cultivation of microorganisms utilizes modern, semi-automated platforms with various sensors monitoring the whole process. One of the examples is Chi.Bio, an open-source bioreactor, originally developed as a small and affordable platform for in situ cultivation [1]. Unfortunately, its measuring capacity is limited to mostly optical and thermal sensors. Some of the basic and useful parameters, including pH, are not available in commercially available setup. In our study, we expanded Chi.Bio’s capacity for a pH measurement allowing continuous monitoring with a commonly available pH probe. Our approach builds on recently published work by Denton et al. (2024) [2]. However, we introduced numerous hardware and software modificat ions to both, the original Chi.Bio system and the augmentation by Denton et al. The project began as a breadboard prototype that combined the original bioreactor hardware with an Atlas Scientific Embedded pH Circuit, an Arduino Nano, and a Mikroe pH Click board. This basic hardware setup was used to develop and improve the software components, implemented in Python, HTML, and JavaScript. The final assembly, however, eliminated the need for any additional microcontroller, and the integration of a voltage transformer reduced the pH-electrode hardware to a compact 5 × 5 cm low-cost module with a single connection cable to the bioreactor. The resulting setup was tested in a simple two-day in vitro experiment based on E. coli cultivation, evaluating the relationship between sample optical density (used as a proxy for cell number) and externally modified pH achieved by gradual additions of 30% NaOH. During the experiment, five additions of lye were performed (10, 20, 30, 80, and 200 μL). Each addition resulted in a stepwise pH increase accompanied by a moderate decrease in optical density. Results showed that the pH module can be reliably used for experimental purposes. It provides stable readings, is easy to handle, and allows straightforward retrieval of pH data directly from the data table after the experiment. Thus, our custom-made Chi.Bio platform now supports real-time pH monitoring in a small-scale, low-cost setup, and represents a perfect platform to integrate additional sensors in our future work.

Chi.Bio bioreactor, pH sensing module, hardware and software modification, Real-time microbial cultivation monitoring, optical density–pH correlation

Chi.Bio bioreactor, pH sensing module, hardware and software modification, Real-time microbial cultivation monitoring, optical density–pH correlation

ALEKSANDRENKO, B.; SÚKENÍK, M.; SEDLÁŘ, K.

27.11.2025

Vysoké učení technické v Brně

Brno

978-80-214-6388-2

Studentská odborná konference CHEMIE JE ŽIVOT 27—11— 2025 sborník abstraktů

35

35

91

https://www.fch.vut.cz/vav/konference/sok/vystupy/sok-2025-sbornikabstraktu-pdf-p321225