Robotic capsule for sampling gut microbiota : design, development and evaluation : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Palmerston North, New Zealand

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Massey University
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In this research, a pill-sized robotic capsule was developed that can collect gut microbiota both from the gut lumen (capsule surroundings) and intestinal wall (mucosa layer). Initially, the peristaltic forces exerted on the robotic capsule inside the gut were quantified so the working environment of the capsule could be understood. Secondly, a unique sampling mechanism was developed that could gently scrape the content from the gut lining and could provide a full length assessment of microbiota after capsule retrieval. Thirdly, the design of shape memory alloy (SMA) spring actuator was realised that could apply sufficient force to overcome peristaltic and frictional forces for sample collection at the target-site. Furthermore, an actuation system was devised by tackling the high-drain current requirement of SMAs. Fourthly, a sealing mechanism was developed to secure the collected sample from cross contamination and to assure successful encapsulation. Fifthly, the robotic capsule was rigorously tested in various in vitro simulators replicating the gut environment and a dedicated gut simulator that mimicked the in-vivo environment to ensure successful and safe travel of the capsule along the gastrointestinal tract. Finally, an in vitro experimental setup that kept an intestine alive for 6 hours was used to optimise the sample collection process. The robotic capsule collected sufficient quantities of sample (more than 100 µL) for microbiota analysis from living intestines of three animal species (pig, sheep and cow) during the trials. The study of gut microbiota is gaining increasing attention due to its direct impact on human health. Gut microbiota can provide comprehensive information about the health of a host, and it can help in the early diagnosis of diseases like cancer, diabetes, obesity, etc. The robotic capsule prototype, developed in this work, has a potential to become a vital apparatus for clinicians and scientists to sample human and animal gut in the future.
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Robotics, Robotics in medicine, Gastrointestinal system, Microbiology, Sampling