Robotic Actuation Module Toward a Subepithelial Serotonin-Sensing Ingestible Capsule

This manuscript reports the successful demonstration of a cam and follower (CnF) mechanism for reversible actuation of a microneedle (MN)-based electrochemical biosensor for the detection of subepithelial serotonin (5-hydroxytryptamine, 5-HT) in the gastrointestinal (GI) tract. We successfully integrated our previously developed biosensor [1] with a meso-scale electromechanical actuator to create a module for real-time quantification of subepithelial-5-HT. This module addresses the need to drive the biosensor into the subepithelial space from an ingestible capsule to investigate the role of 5-HT in the gut-brain axis (GBA). The CnF mechanism actuates the sensor into the GI wall with 3.85 mN of force to perform electrochemical 5-HT measurements and retracts into the capsule shell for subsequent deployment. This work demonstrates a realistic method for accessing subepithelial 5-HT from a capsule device and is a significant step toward establishing a new paradigm for studying 5-HT dynamics.