Step-by-step methodology for building a capsule to sample small intestine content

Abstract

Background Research on the intestinal microbiome has been hindered by limited access to intestinal content. Recently, a few capsule prototypes have demonstrated their potential for sampling intestinal material. However, access to these capsules is restricted because most of them are not yet commercially available. Pigs offer significant potential to inform human research due to the many physiological similarities between the two species. However, the unique features of pig anatomy have made it difficult to conduct research using swallowable solid devices. This article provides a detailed account of the manufacturing process and composition of a capsule, along with all the necessary steps for successfully sampling small intestine content in pigs. Results The capsule moves passively through the digestive tract, relying solely on intestinal peristalsis for propulsion. Engineered to open when it encounters a pH level greater than 6, the upper part dissolves, allowing intestinal fluids to enter. This triggers a plunger to expand, drawing luminal content into the storage chamber. Once the plunger mechanism is fully extended the capsule is automatically sealed. The capsule has a size 0 hard capsule and consists of two main components: a dissolvable exterior with an enteric coating and a 3D-printed bottom part. The printing files of the 3D-printed bottom part are provided for replication. In vitro testing shows that the capsule can withstand two hours in an acidic medium and successfully samples within an hour of being transferred to a neutral medium. When tested in vivo in pigs, the capsule successfully collected intestinal content from the upper and middle sections of the small intestine, depending on the size of the pig. Conclusions This article provides essential details for the rapid development of a cost-effective tool that has been already validated for non-invasive sampling of small intestine content in pigs. By providing access to the exact production steps and printing files, this article empowers others to innovate and expand upon this foundational work. This open-source approach opens up new avenues for intestinal research, making it more accessible and adaptable for a wide range of studies in both animal and human models.