Abstract: Commercialized capsule-type endoscopes move passively by peristaltic waves (and gravity), which makes it difficult for doctors to diagnose the areas of interest more thoroughly and actively. To resolve this problem of passivity, it is necessary to find a special locomotion principle, which fits the gastrointestinal (GI) tract. In this paper, a legged locomotive mechanism with shape memory alloy (SMA) actuation based on the peristaltic principle is proposed, and then the structure of the locomotion mechanism is introduced. Based on the preliminary results, the design, modeling, and fabrication of an SMA microactuation concept for application in an endoscopic capsule are given, as well as the SMA spring and legged component design, which is the core section of the system design. We used the pseudo-rigid-body model (PRBM) to analyze nonlinear and large deflections of the SMA legged component. Thus, a prototype endoscope with an SMA spring and six legged components was designed and fabricated. It is 15 mm in diameter and 33 mm in total length, with a hollow space to house other parts needed for endoscopy such as a camera, a radio frequency (RF) module, and sensors. During testing, the locomotive mechanism was effective in a plastic tube environment.

Key words: Capsular endoscopy, Shape memory alloy (SMA), Microactuation, Locomotion

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