Institute of Robotics and Intelligent Systems, ETH Zurich, Zurich, CH-8092, Switzerland.
Robotics Engineering Department, Daegu Gyeongbuk Institute of Science and Technology (DGIST), 711-873, Daegu, South Korea.
Small. 2019 Apr;15(16):e1805006. doi: 10.1002/smll.201805006. Epub 2019 Mar 4.
Biocompatibility and high responsiveness to magnetic fields are fundamental requisites to translate magnetic small-scale robots into clinical applications. The magnetic element iron exhibits the highest saturation magnetization and magnetic susceptibility while exhibiting excellent biocompatibility characteristics. Here, a process to reliably fabricate iron microrobots by means of template-assisted electrodeposition in 3D-printed micromolds is presented. The 3D molds are fabricated using a modified two-photon absorption configuration, which overcomes previous limitations such as the use of transparent substrates, low writing speeds, and limited depth of field. By optimizing the geometrical parameters of the 3D molds, metallic structures with complex features can be fabricated. Fe microrollers and microswimmers are realized that demonstrate motion at ≈20 body lengths per second, perform 3D motion in viscous environments, and overcome higher flow velocities than those of "conventional 3D printed helical microswimmers." The cytotoxicity of these microrobots is assessed by culturing them with human colorectal cancer (HCT116) cells for four days, demonstrating their good biocompatibility characteristics. Finally, preliminary results regarding the degradation of iron structures in simulated gastric acid liquid are provided.
生物相容性和对磁场的高响应性是将磁性微型机器人转化为临床应用的基本要求。磁性元素铁表现出最高的饱和磁化强度和磁化率，同时表现出优异的生物相容性特征。在这里，提出了一种通过 3D 打印微模具中的模板辅助电沉积可靠地制造铁微机器人的方法。3D 模具是使用改进的双光子吸收配置制造的，该配置克服了以前的限制，例如使用透明基板、低写入速度和有限的景深。通过优化 3D 模具的几何参数，可以制造具有复杂特征的金属结构。实现了 Fe 微滚轮和微游泳者，它们以 ≈20 个体长/秒的速度运动，在粘性环境中进行 3D 运动，并克服了高于“传统 3D 打印螺旋微游泳者”的流速。通过将这些微机器人与人结肠癌细胞（HCT116）共培养四天来评估它们的细胞毒性，证明了它们良好的生物相容性特征。最后，提供了关于模拟胃酸液体中铁结构降解的初步结果。
