Magnet-Driven Microwalker in Surface Motion Based on Frictional Anisotropy

Untethered magnet-driven microrobots play an increasingly important role in various biomedical applications. Incorporating bionic technology into microrobot design is an emerging way to improve the work efficiency of microrobots. Herein, a magnetically powered and frictional anisotropy-based microwalker that can be potentially used in in vivo nonliquid-filled environment is proposed. The microwalker is constructed by two rigid segments with an equal length of 70 mu m, connected by a rigid joint. Parallel gecko setae-like tentacles are placed at the bottom of the segments as contact feet to generate friction with the contact surface. The microwalker is integrally fabricated from biocompatible materials with 3D laser lithography based on two-photon polymerization. The microwalker can be well controlled to move in low-Reynolds (Re)-number regimes under an external oscillating magnetic field. In addition to moving in a liquid environment as existing microswimmers, the microwalker can move in surface in a nonliquid-filled environment. It can also climb the slope driven by the planar magnetic field only. Several experiments were conducted to demonstrate good motion capability of the microwalker. This study provides a new solution to microrobot design for future biomedical applications.