Electronics-free soft robotic minitablet for on-demand gastric molecular sensing and diagnostics in vivo

Real-time biomarker sensing and molecular sampling in the stomach can transform how gastrointestinal disorders are diagnosed and managed-yet integrating both capabilities into a single ingestible platform remains a formidable challenge. Existing devices often struggle with size constraints, limited functionality, and the mechanical mismatch between soft, biocompatible materials and rigid electronics. Here, we present SeroTab, an electronics-free soft robotic minitablet that combines real-time pH sensing with on-demand gastric fluid sampling in vivo. Inspired by the gliding motion of penguins through viscous environments, SeroTab features a magnetically actuated, curvature-adaptive body that enables autonomous navigation through complex anatomical geometries to specific gastric regions. Upon reaching its target, a shape memory polymer actuator-triggered wirelessly via radio frequency heating-draws gastric fluid into an internal reservoir (up to 35 microliters). A pH-sensitive hydrogel within the chamber, embedded with biocompatible metal disks, enables ultrasound-based pH readout across a physiologically relevant range (pH 2 to 7) and preserves the sample for untargeted metabolomic profiling. In vivo studies in animal models demonstrate SeroTab's ability to detect pharmacologically induced pH changes (ΔpH = 4, from 2 to 6) and metabolic shifts (42 detected metabolites) following omeprazole administration. By uniting soft robotics, responsive materials, and wireless actuation, SeroTab paves the way for minimally invasive, outpatient-compatible diagnostics that can advance early screening and streamline clinical decision-making.