Actuation and locomotion of MR-LF. (A) A magnetic robot with localized flexibility (MR-LF) navigating through a biological lumen. Rotation of the actuator dipole induces the body bending used for locomotion. (B) Image of fingers holding the fabricated MR-LF. Scale bar: 10 mm. (C) Cross-section illustrations of MR-DF and MR-LF compared to the ingestible PillCam™ SB 3 capsule endoscopy device. MR-DF: magnetic robot with distributed flexibility. (D) Schematic of the experiment setup. A robot in a confined channel is actuated by a rotating actuator magnet at a distance ya relative to the robot’s initial position (x = 0, y = 0). (E) Illustrations (left) and side-view image compositions (right) of an MR-DF (top) and an MR-LF (bottom), both having a mass of 2.55 g. Images demonstrate similar locomotion at ya = 11 cm with time and step number labels and a displacement scale below. (F) Comparison of the initial speed (average speed of the first ten steps) of an MR-DF (black data) with an MR-LF (red data), both having a mass of 2.55 g. Boxes show the 25-75% range, whiskers indicate min-max, and markers indicate mean (n = 5).