Inchworm-Like Biomimetic Magnetic-Driven Robotic Shell for Capsule Endoscope in a Tubular Environment

As a vital tool for diagnosing intestinal diseases, wireless capsule endoscopy traditionally relies on passive movement through intestinal peristalsis. To address the limitations of passive locomotion, we introduce a novel inchworm-like biomimetic magnetic-driven robotic shell that enhances active locomotion capabilities within complex tubular environments. This innovative design employs a magnetic torsion spring for dynamic extension and contraction movements, which can be controlled via an external magnetic field. In addition, the shell is equipped with flexible bristles, facilitating a differential friction effect that significantly augments its inchworm-like crawling motion. Force and torque analysis have been conducted in detail to optimize the design and functionality. A prototype with a diameter of 16 mm and a length of 31.3 mm was developed and integrated with a commercial capsule endoscope for rigorous testing. Experimental evaluations across various setups, including phantoms, in vitro porcine intestines, and in vivo intestinal experiment. The results demonstrated the shell is capable to effectively pass through the tubular environments. The capsule robot achieved an average speed of 2.63 mm/s in the in vitro intestinal experiment and 2.7 mm/s in the in vivo intestinal experiment.