Magnetic Capsule for Stable Collection of Large GI Tract Microbiome Samples

The gut microbiome is an important indicator and determinant of human health, but current methods to sample intestinal contents are insufficient. Robotic sampling capsules hold the unique potential to sample contents in a non-invasive manner for safe study and diagnosis, but suffer from low sampling volume and poor sealing robustness. We introduce a new tetherless magnetically actuated capsule designed for noninvasive sampling of GI liquid digesta for study. The design uniquely maximizes sampling volume efficiency, utilizing 52 % of its space (290 mg) for the sample, compared to roughly 10 % in previous magnetic hinge designs. Controlled by low strength magnetic fields, the capsule operates without onboard control circuits, enabling sampling anywhere along the GI tract. Strong magnetic sealing forces (2.8 N) prevent leakage or contamination of the sample. The capsule's compact size (8 mm diameter, 11 mm length) is similar to existing FDA approved GI capsules, allowing safe transit through the body. It features a wide opening angle of 144 degrees, and stays closed for low fields to avoid accidental opening (the hinge snaps open to 83 % of its maximum opening angle within an increment of just 2 mT of the last closed point). The capsule's robust design withstands GI pressures (roughly 10 kPa).