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.This work was supported by the ATLAS project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 813782.This work was also part of the CISAS (MIUR-CNR) project, funded by the Italian Ministry of University and Research.Peer ReviewedPostprint (author's final draft