Inchworm-Like Microrobot for Capsule Endoscope

The conventional endoscopes generate pains and discomfort to patients due to the stiffness of their body and cannot reach to small intestines. Therefore, the wireless capsule-type endoscope, M2A, has been developed. However, commercialized capsule-type endoscopes move passively by peristaltic waves (and the gravity), which has limitation for doctors to diagnose more thoroughly and actively. In order to solve this problem, a locomotive mechanism is proposed for wireless capsule-type endoscopes. Based on the tests of various actuators, spring-type SMA actuators are selected as micro actuators for capsule endoscopes. Thus, two-way linear actuators using a pair of SMA springs are developed based on a static analysis on them. Moreover, a simple and effective clamping device is developed based on biomimetic approach. A prototype endoscope with four pairs of SMA springs and four clampers was developed. It is 13 mm in diameter and 33mm in total length, with a hollow space of 7.6 mm in diameter to comprise endoscope components such as a camera, and communication module, sensors, and a battery. A sequential control of the four actuation modules improves the efficiency of locomotion up to four times. For feasibility test of proposed locomotive mechanism, a series of experiments were carried out including in-vitro tests. Based on results of the experiments, we conclude that the proposed locomotive mechanism is effective to be used for micro capsule-type endoscopes