The objective of the present work is to allow noninvasive sampling of microbiota, until now, surgery is still needed to collect intestinal liquid samples. Given the recent developments of endoscopic capsules and their added value for the diagnosis and the treatment of gastrointestinal pathologies, the paper is focused on the design of a microbiota sampling capsule. The device has to offer an efficient collection of intestinal liquid and at the same time to protect it from any contamination as the device navigates out of the human body. To ensure this and safety at the same time, a passive capsule is developed based on a bistable mechanical structure actuated by an expanding foam that itself collects the intestinal fluid. The device is developed using additive manufacturing. It is shown that the process is compatible with the production of the complete capsule with biocompatible material, while ensuring the presence of bistability for capsule closing. In-vitro trials validate the operating mode of the capsule. This work represents a significant step toward the creation of simple and yet efficient tools to better understand microbiota impact and future pathology detection.