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.
Highlights
Colorectal cancer (CRC) has caused more than 880 thousand deaths in 2018, ranking the second most deadly and third most common cancer worldwide [1,2]
An external permanent magnet is installed on the end-effector of a robotic manipulator, and an internal permanent magnet is embedded inside the endoscopic capsule
Due to the complex structure of the human large intestine and asynchronous motion of the external permanent magnet (EPM) and the internal permanent magnet (IPM), the maneuverability of the magnetic capsule is inevitably restricted during a colonoscopy
Summary
Colorectal cancer (CRC) has caused more than 880 thousand deaths in 2018, ranking the second most deadly and third most common cancer worldwide [1,2]. Using the magnetic localization method, IMU, and dipole model, researchers can control the magnetic force along the opposite direction of gravity, and use a control strategy that, by counteracting gravity, achieves magnetic levitation of the capsule endoscope [24] They attain 19.5% of contact with the colon wall in experiments performed on a colonoscope training simulator. We design a magnetically-guided capsule endoscope with flexible force sensors Through these sensors, the interaction force that the internal permanent magnet applied on the intestinal wall is measured to avoid intestinal injury and the loss of magnetic coupling during colonoscopy.
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