Design of a magnetic actuation system for a microbiota-collection ingestible capsule

Minimally invasive wireless devices, allowing the sampling of gut's bacteria, are needed for a longitudinal understanding of the role of the microbiota on the human health. Herein, we present a novel magnetic actuation system fitting inside a 11.5 x 30.5 mm wireless ingestible capsule. Lacking any electronic components, the capsule robot is designed for the collection of microbiota's samples through mechanical brushing. Wireless activation and in situ sampling are enabled by an external permanent magnetic source. This component, when approaching the capsule, progressively allows: (1) the adhesion of the device to the mucosa, (2) the exposure of the brushes, and (3) the sampling by multiple rotations. Numerical and analytical models were developed for dimensioning the system, and were validated by benchtop experiments.