Endoluminal Motion Recognition of a Magnetically-Guided Capsule Endoscope Based on Capsule-Tissue Interaction Force

Abstract

A magnetically-guided capsule endoscope, embedding flexible force sensors, is designed to measure the capsule-tissue interaction force. The flexible force sensor is composed of eight force-sensitive elements surrounding the internal permanent magnet (IPM). The control of interaction force acting on the intestinal wall can reduce patient’s discomfort and maintain the magnetic coupling between the external permanent magnet (EPM) and the IPM during capsule navigation. A flexible force sensor can achieve this control. In particular, by analyzing the signals of the force sensitive elements, we propose a method to recognize the status of the motion of the magnetic capsule, and provide corresponding formulas to evaluate whether the magnetic capsule follows the motion of the external driving magnet. Accuracy of the motion recognition in Ex Vivo tests reached 94% when the EPM was translated along the longitudinal axis. In addition, a method is proposed to realign the EPM and the IPM before the loss of their magnetic coupling. Its translational error, rotational error, and runtime are 7.04 ± 0.71 mm, 3.13 ± 0.47∘, and 11.4 ± 0.39 s, respectively. Finally, a control strategy is proposed to prevent the magnetic capsule endoscope from losing control during the magnetically-guided capsule colonoscopy.

Current Engineering Developments for Robotic Systems in Flexible Endoscopy

“…However, the proposed method can only be applied to limited scenarios where external forces are exerted at the tip of the endoscope alone, with no external loads on the endoscope backbone. Zhang et al 56 developed a flexible tactile sensor (shown in Figure 5) to estimate exerted forces on surrounding tissues, employing a sensor composed of piezoresistive elements placed on a flexible printed circuit. Originally developed for a tethered capsule endoscope to monitor forces exerted on the colonic mucosa, the compliance of the sensor renders it suitable for soft continuum endoscopes.…”

Medical Robotics: Opportunities in China

“…Due to the high dietary risk in the Chinese population, there is great demand for digestive tract endoscopy. Hence, capsule endoscopic robots have attracted extensive attention because they can easily enable comfortable examinations (122,123). In 2016, NaviCam, a magnetically driven capsule endoscopic robot, was developed by ANKON Technology Company and approved by the CFDA.…”