Multi-Material 3D-Printed Magnetic Millirobot for Quadrupedal Locomotion in Endoluminal Spaces

Abstract

Quadrupedal locomotion have advantages of a low center of gravity, broad support base, and four-legged coordination, enabling outstanding stability in complex terrains. Drawing inspiration from this, researchers have developed robots emulate such locomotion through multiple actuations controlling and structural reconfiguration. However, complex control sequences and slow tethered actuation limit their locomotion in confined endoluminal spaces. Here, we present a quadrupedal magnetic millirobot (beamrobot) fabricated via multi-material direct ink writing (DIW) for medical applications in complex endoluminal spaces. The millirobot combines a soft body with magnetic feet, enabling controlled shape-morphing and locomotion under external magnetic fields. The printing parameters are optimized. The numerical simulations and experiments validate the static deformation and dynamic locomotion modes. Experimental results demonstrate the versatility of the beamrobots, including following "U"-shaped trajectories, displaying movement in the branch vessel model, and clearing the obstruction in the vessel model. The proposed quadrupedal magnetic millirobot and hard-magnetic actuation approach open up new possibilities for the medical applications.