Park Jeong Eun, Kwon Seung Hyuk, Lu Qi, Choi Hyoung Jin, Wie Jeong Jae
Department of Organic and Nano Engineering, The Research Institute of Industrial Science, Hanyang University, Seoul, 04763, Republic of Korea.
Program in Environmental and Polymer Engineering, Inha University, Incheon, 22212, Republic of Korea.
Small. 2024 Feb;20(6):e2305272. doi: 10.1002/smll.202305272. Epub 2023 Sep 13.
The magnetomechanical actuation of micropillars is developed for the contactless manipulation of miniaturized actuators and microtextured surfaces. Anisotropic geometry of micropillars can significantly enhance the magnetic actuation compared with their isotropic counterparts by directional stress distributions. However, this strategy is not viable for triangular micropillars owing to insufficient anisotropy. In this study, a significant improvement in the magnetic actuation of triangular micropillars using composite magnetic particles is reported. A minute and optimal amount of hard magnetic gamma-ferrite nanorods are hybridized with soft magnetic iron microspheres to generate synergistic effects of magnetic coupling and percolation phenomenon on the magnetic actuation of polymer composites. The addition of 1 wt% face-centered cubic-phased gamma-ferrite nanorods suppresses the magnetic coupling interference of body-centered cubic-phased iron microspheres. Furthermore, the nanorods reduce the percolation threshold by participating in the percolation of the microspheres. A systematic compositional study on the magnetization and magnetorheological properties reveals that the coupling effect dominates the percolation effect at a low magnetic field, whereas the percolation effect governs the magnetic actuation at a high magnetic field. This hybrid approach can help in designing material constituents for effective magnetic actuators and robotic systems that can sensitively respond to an external magnetic field.
微柱的磁机械驱动技术是为实现对小型致动器和微纹理表面的非接触式操纵而开发的。与各向同性微柱相比，微柱的各向异性几何结构可通过定向应力分布显著增强磁驱动效果。然而，由于各向异性不足，这种策略对三角形微柱不可行。在本研究中，报告了使用复合磁性颗粒对三角形微柱的磁驱动性能有显著改善。将微量且最佳量的硬磁γ-铁氧体纳米棒与软磁铁微球混合，以在聚合物复合材料的磁驱动中产生磁耦合和渗流现象的协同效应。添加1 wt%的面心立方相γ-铁氧体纳米棒可抑制体心立方相铁微球的磁耦合干扰。此外，纳米棒通过参与微球的渗流降低了渗流阈值。对磁化和磁流变特性的系统成分研究表明，在低磁场下耦合效应主导渗流效应，而在高磁场下渗流效应控制磁驱动。这种混合方法有助于设计用于有效磁致动器和机器人系统的材料成分，使其能够对外部磁场做出灵敏响应。
