Wirelessly Powered Ingestible Capsule for Optical Stimulation of the Gastrointestinal Tract in Rodents

Abstract

Optogenetics enables cell-specific activation and inhibition of neurons. The gut contains intricate networks of enteric and central neurons, but in vivo investigation is difficult due to its motile and harsh environment. This work reports an ingestible electronic capsule for non-invasive optical gut stimulation (ICOPS) in rodents. ICOPS is wirelessly powered via a transmitter coil, delivered by oral gavage, and excreted safely without obstruction within 20 h. The device integrates a micro-light-emitting diode (µLED) operating at 470 nm—a standard wavelength for channelrhodopsin-2 activation—together with a 460-turn ferrite-core coil and a shunt capacitor. Optimized circuits enable efficient power transfer at low frequencies (45–140 kHz), addressing weak coupling and misalignment. ICOPS operates effectively up to 14 cm longitudinally, 9 cm laterally, and at 75° rotation relative to the magnetic field. Specific absorption rate (SAR) analysis confirms exposure within safe occupational limits at 6 A and 45/63 kHz. In vivo validation using an in vivo imaging system (IVIS) and micro-computed tomography (µCT) confirms functionality and safety. ICOPS is the first rodent-scale ingestible capsule fabricated entirely in-house using 3D printing, without the need for cleanroom facilities, providing a compact, scalable platform for non-invasive optogenetic modulation of enteric circuits.