A millimeter-scale capsule robot driven by a piezoelectric motor in tubular environments

Abstract In this study, we propose a millimeter-scale capsule robot that can effectively swim in sub-centimeter-scale tubular environments. The capsule robot is mainly composed of a micro piezoelectric motor, a 3D printing shell, and a propeller. The piezoelectric motor rotates the propeller to push the capsule robot forward or backward swimming. The dimensions of the piezoelectric motor and the capsule robot are 2.8 mm × 2.8 mm × 30 mm and Φ 6 × 32 mm 3 , respectively. The experimental results show that the maximum rotational speed of the prototype motor is 7824 r min −1 . The maximum forward and backward velocities of the prototype robot can reach 124 mm s −1 (3.875 BL s −1 ) and 158 mm s −1 (4.9375 BL s −1 ), respectively. Combined with the flexibility of the piezoelectric actuator structure, the capsule robot can further reduce its size to meet complex pipeline environments such as human blood vessels and pipelines. This work will create new opportunities for the advancement of sophisticated and flexible actively controlled capsule robots.