Design of a Versatile Microrobot for Cargo Delivery

Mobile untethered magnetic microgrippers can actively select targets for transportation in enclosed environments, which has significant implications for on-chip microparticle manipulation, biopsy, and assisted reproduction. Nevertheless, current magnetic microgrippers require complex fabrication processes and additional stimuli and are only applicable for targets larger than 0.3 mm in size. This article presents an articulated versatile microgripper, which relies solely on magnetic fields to achieve capture-release and transportation tasks and can be mass-produced based on direct laser writing technology. The proposed microrobot consists of two partially magnetized claws and relies on wall adhesion and friction to achieve relative motion between magnetized and nonmagnetized claws. Three biomimetic locomotion modes, including bird-beak-inspired opening and closing, armadillo-inspired rolling, and inchworm-inspired crawling, are developed for cargo delivery tasks. The influence of fabrication and structural parameters on mobility and capture capability are analyzed. Motion performance under different scenarios is investigated to characterize the relationship between velocity and magnetic field rotation/ oscillation frequency. Cargo capture-release experiments are further performed to demonstrate that targets above 0.04 mm can be captured.