Active Multiple-Sampling Capsule for Gut Microbiome

It is well known that the gut microbiome performs necessary physiological functions for the host organism, such as preventing infection from various pathogens, promoting the immune system's maturation, participating in nutrition absorption and metabolism processes, and promoting anticancer functions. To understand the relationship between the gut microbiome and host, multiple microbial samplings and analyses from certain locations in the gastrointestinal (GI) tract are necessary. However, ingestible sampling capsules, previously designed for gut-microbiome sampling, rely on the peristaltic motion of the intestine and can perform sampling only once, when the capsule body is submerged in the gut fluid. In this article, we propose an active multiple-sampling capsule that can be actively moved (by an external magnetic field) to specific locations in the GI tract and collects multiple gut-microbe-containing intestinal fluid samples. In particular, because the proposed capsule includes three microchannels, three inlet ports, and a small permanent magnet (for alignment), it can perform selective sampling with minimal cross-contamination, by allowing the capsule to move to the target location and aligning the inlet port of one of the three microchannels downwards. Through basic performance tests, we evaluate the locomotive and microbial-sampling performances of the proposed capsule (locomotion accuracy: ∼1.39°; inlet-port alignment accuracy: ∼1.48°; maximum suction flow rate: 22.3 μL/min); furthermore, through phantom and ex vivo tests, we verify the feasibility of the proposed capsule. We confirm that the proposed active multiple-sampling capsule can be moved to the desired target locations in the GI tract and can collect ∼45 μL gut-microbe-containing intestinal fluid thereat; furthermore, it can perform up to three samplings with minimal cross-contamination. In the future, we expect the proposed capsule to be implemented in medical research, to understand the gut microbiome's role in the human body (via the collection and analysis of these microbiomes) and to diagnose various human diseases.