Xu Tianqi, Zhang Jiachen, Salehizadeh Mohammad, Onaizah Onaizah, Diller Eric
Department of Mechanical and Industrial Engineering, Microrobotics Laboratory, University of Toronto, 5 King's College Rd., Toronto, Ontario M5S 3G8, Canada.
Sci Robot. 2019 Apr 24;4(29). doi: 10.1126/scirobotics.aav4494.
Flexible magnetic small-scale robots use patterned magnetization to achieve fast transformation into complex three-dimensional (3D) shapes and thereby achieve locomotion capabilities and functions. These capabilities address current challenges for microrobots in drug delivery, object manipulation, and minimally invasive procedures. However, possible microrobot designs are limited by the existing methods for patterning magnetic particles in flexible materials. Here, we report a method for patterning hard magnetic microparticles in an elastomer matrix. This method, based on ultraviolet (UV) lithography, uses controlled reorientation of magnetic particles and selective exposure to UV light to encode magnetic particles in planar materials with arbitrary 3D orientation with a geometrical feature size as small as 100 micrometers. Multiple planar microrobots with various sizes, different geometries, and arbitrary magnetization profiles can be fabricated from a single precursor in one process. Moreover, a 3D magnetization profile allows higher-order and multi-axis bending, large-angle bending, and combined bending and torsion in one sheet of polymer, creating previously unachievable shape changes and microrobotic locomotion mechanisms such as multi-arm power grasping and multi-legged paddle crawling. A physics-based model is also presented as a design tool to predict the shape changes under magnetic actuation.
柔性磁性小型机器人利用图案化磁化实现快速转变为复杂的三维（3D）形状，从而获得运动能力和功能。这些能力解决了当前微型机器人在药物递送、物体操作和微创手术方面面临的挑战。然而，现有的在柔性材料中对磁性颗粒进行图案化的方法限制了可能的微型机器人设计。在此，我们报告了一种在弹性体基质中对硬磁性微粒进行图案化的方法。该方法基于紫外（UV）光刻技术，利用磁性颗粒的可控重新定向和对紫外光的选择性曝光，将具有任意3D取向且几何特征尺寸小至100微米的磁性颗粒编码到平面材料中。在一个过程中，可以从单一前驱体制备出多个具有不同尺寸、不同几何形状和任意磁化分布的平面微型机器人。此外，3D磁化分布允许在一片聚合物中实现高阶和多轴弯曲、大角度弯曲以及弯曲和扭转的组合，从而产生以前无法实现的形状变化和微型机器人运动机制，如多臂强力抓取和多腿桨式爬行。还提出了一个基于物理的模型作为设计工具，以预测磁驱动下的形状变化。
