A Self-Driven Superlubricated Capsule Enabled by a Chemical-Fluidic-Mechanical Cascade for Effective Gastric Fluid Sampling.

Gastrointestinal fluid sampling plays a pivotal role in early detection of gastrointestinal diseases, yet conventional methods are invasive, uncomfortable, and susceptible to sample contamination. Here, we developed a self-driven superlubricated capsule (GFSCap) that achieved autonomous gastric fluid sampling and sealing. A chemical-fluidic-mechanical cascade was implemented, in which dissolution of a trigger film opened the sampling pathway, while a mechanically precompressed collector facilitated fluid uptake. Subsequently, hydrogel swelling drove a piston to close the sampling channels and retain the collected sample. Furthermore, the capsule surface was modified with a superlubricated copolymer, which substantially reduced interfacial friction and cell adhesion. Under in vitro conditions, the GFSCap collected approximately 230 mg of simulated gastric fluid within 30 min, while the proof-of-concept in vivo experiment in an anesthetized pig yielded approximately 127 mg of native gastric fluid. Simulated esophageal retrieval experiments showed that the sealed capsule retained most of the collected sample. Additionally, DNA recovery remained above 93.8% after exposure to individual GFSCap material extracts and reached 98.7% after exposure to combined material extracts, supporting the compatibility of the GFSCap material system with representative downstream nucleic acid analysis. Overall, the GFSCap provided a self-driven platform integrating gastric fluid sampling, sealing, lubrication, and controllable retrieval.