Seropill: Novel Minimally Invasive Ingestible Capsule for Serotonin Sensing in the GI Tract

This paper reports the first serotonin (5-HT) sensing ingestible capsule allowing minimally invasive real-time in vivo detection of luminally released serotonin in the gastrointestinal (GI) tract. The system utilizes a surface-mounted sensor with an Au-carbon nanotube (CNT) working electrode, Au counter electrode, and Ag/AgCl reference electrode. The capsule uses previously reported electronics packaged in a 3D-printed ASA shell to perform cyclic voltammetry, allowing the detection and quantification of local serotonin concentration with a dynamic range of 2-10 µM. This device marks a step toward wireless ingestible systems for real-time evaluation of gastrointestinal microbiome metabolites in vivo.