Resonance-based design of wireless magnetic capsule for effective sampling of microbiome in gastrointestinal tract

Abstract

This paper proposes a wireless magnetic capsule for effectively sampling the microbiome in the human gastrointestinal tract. Existing magnetically actuated sampling capsules suffer from limited actuation distance, which require a large magnetic field at least 14 mT for actuation. The capsule proposed in this work reduces the required magnetic field to 6 mT using a resonance-based design. This novel capsule contains two rotatable actuation magnets (AMs), whereby the attractive force between the two magnets increases in proportion to their angle, resulting in a magnetic spring whose stiffness can be tuned in the design process. To enable contamination free preparation of the sampling space, sealing magnets are attached to covers to lock the capsule during GI-tract passage. The capsule opening mechanism is simulated using a physics-based model of the capsule actuation based on the magnetic spring design. According to the simulation results, a capsule with a size similar to that of existing ingestible capsules (length and height of 26 mm and 12.4 mm, respectively) is designed. The prototyped capsule comprises biocompatible materials, and its sampling and sealing ability are verified using a digestive material model. Results suggest that the capsule can enable effective sampling in the human gastrointestinal tract, with increased actuation distances.