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Design and Investigation of a Wireless Robotic Capsule System for Facilitating Gastrointestinal Sensor Implantation
Recently, medical capsules (MCs) have evolved from pure diagnosis devices to multipurpose medical capsule robotic (MCR) systems. Several research groups are investigating the feasibility of performing drug delivery, biopsy, sensor implantation, and minimally invasive surgery in the gastrointestinal (GI) tract with MCs. A GI sensor implantation capsule robot (GSICR) was invented to implant biosensors, which could enable long-term monitoring of in vivo body parameters (temperature, pH, pressure, etc.) for obtaining better clinical outcomes. Reliable capsule localization and locomotion solutions could improve current MC technology. An understanding of capsule-tissue interaction could provide physiology reference for refining the design of MCRs. For example, the contact pressure between a capsule and the small intestine could be used to estimate the friction experienced by an active capsule. In this study, several MC prototypes for measuring the contact pressure between the capsule and the small intestine were developed. Two pressure sensors were deployed to measure and differentiate the contact pressure and the small intestine intraluminal pressure. After in vitro calibration and validation, these prototypes were tested in live animal models. The measured pressure signals were analyzed in the time and frequency domains. A mathematical model was presented to describe the physiological factors influencing the contact pressure. Besides the contraction of the small intestine tissue, the respiration, heartbeat, and weight of surrounding tissue also influence the contact pressure. Current capsule localization methods based on radio frequency (RF) signals, magnetic fields, X-rays, etc. need external sensors/devices, while pH-based localization only provides general information (e.g., the GI organ the capsule resides in). Based on a simplified model of the capsule’s motion in the small intestine, a self-contained capsule localization method was presented and a capsule prototype integrated with an inertia measurement unit (IMU) and an optical sensor was developed. After calibration and validation, the capsule’s localization ability was tested by tracking linear, curved and random paths. The result shows the self-contained localization method could be used to track the capsule’s position. Moreover, the capsule tracked its position in a fresh small intestine sample.
Li, Pengbo, "Design and Investigation of a Wireless Robotic Capsule System for Facilitating Gastrointestinal Sensor Implantation" (2017). ETD collection for University of Nebraska - Lincoln. AAI10269726.