Electrochemical Sensor for Ingestible Capsule-Based In-Vivo Detection of Hydrogen Sulfide

We present the fabrication and validation of a thin, flexible electrochemical sensor module for real-time capsule-based detection of hydrogen sulfide (H
2
S) in the gastrointestinal (GI) tract. This work advances ingestible gas sensor design using a nafion solid-state electrolyte and Au electrode to selectively monitor trace physiological H
2
S concentrations within a linear range of 0.9-9 ppm. Pretreatment parameters to optimize nafion conductivity and hydration retention were investigated. Selectivity from known interference gases and operation in humid conditions was compared to a commercial SPEC-H
2
S sensor. The sensor was integrated with a previously reported ingestible capsule to perform amperometric measurements, providing the framework for non-invasive, in-vivo monitoring of gaseous biomarkers in the GI tract.