Inline and continuous gas monitoring in gastrointestinal tract models with carbon nanotube-based chemiresistive sensors

Abstract In-vitro simulators of the human gastrointestinal (GI) tract are remarkable technological platforms for studying the impact of food on the gut microbiota, enabling continuous and real-time monitoring of key biomarkers. In these systems, comprehensive real-time monitoring of gaseous biomarkers is required with a cost-effective approach, which has been challenging to perform experimentally to date. In this work, we demonstrate the integration and in-line use of carbon nanotube (CNT)-based chemiresitive gas sensors coated with a thin polydimethylsiloxane (PDMS) membrane for the continuous monitoring of gases within the Simulator of the Human Microbial Ecosystem (SHIME®). The findings demonstrate the ability of the gas sensor to continuously monitor the different phases of gas production in this harsh, anaerobic, highly humid, and acidic environment for a long exposure time (16 h) without saturation. Our findings thus provide a successful sensor platform for monitoring gaseous biomarkers in real time in an in-vitro system such as SHIME®.