Photothermally Reconfigurable Shape Memory Magnetic Cilia
Photothermally Reconfigurable Shape Memory Magnetic Cilia
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DOI：
10.1002/admt.202000147
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发表时间：
2020-03
影响因子：
6.8
通讯作者：
Jessica A.‐C. Liu;B. Evans;J. B. Tracy
中科院分区：
文献类型：
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作者：
Jessica A.‐C. Liu;B. Evans;J. B. Tracy
刺激响应聚合物对微致动器很有吸引力，因为它们可以很容易地小型化和远程致动，从而实现不受约束的操作。在这项工作中，磁性铁微粒分散在热塑性聚氨酯形状记忆聚合物基体和形成人工，磁性纤毛通过溶剂浇铸在垂直磁场中的两个永磁体之间的差距。通过施加的磁场对准的微粒的磁矩的相互作用驱动磁性纤毛沿着场方向的自组装。由此产生的磁性纤毛可使用光和磁场作为远程刺激来重新配置。通过组合磁致动和光热加热获得的临时形状可以通过关闭光和磁场来锁定。随后，在没有磁场的情况下打开光驱动永久形状的恢复。永久形状也可以在通过施加机械约束和高温退火制备纤毛之后重新编程。空间控制的驱动证明通过施加到阵列的磁性纤毛的光学图案转移的掩模。一个理论模型的开发用于预测形状记忆磁性纤毛的响应，并阐明所观察到的现象背后的物理机制，使纤毛系统的设计和优化的特定应用。
Stimulus‐responsive polymers are attractive for microactuators because they can be easily miniaturized and remotely actuated, enabling untethered operation. In this work, magnetic Fe microparticles are dispersed in a thermoplastic polyurethane shape memory polymer matrix and formed into artificial, magnetic cilia by solvent casting within the vertical magnetic field in the gap between two permanent magnets. Interactions of the magnetic moments of the microparticles, aligned by the applied magnetic field, drive self‐assembly of magnetic cilia along the field direction. The resulting magnetic cilia are reconfigurable using light and magnetic fields as remote stimuli. Temporary shapes obtained through combined magnetic actuation and photothermal heating can be locked by switching off the light and magnetic field. Subsequently turning on the light without the magnetic field drives recovery of the permanent shape. The permanent shape can also be reprogrammed after preparing the cilia by applying mechanical constraints and annealing at high temperature. Spatially controlled actuation is demonstrated by applying a mask for optical pattern transfer into the array of magnetic cilia. A theoretical model is developed for predicting the response of shape memory magnetic cilia and elucidates physical mechanisms behind observed phenomena, enabling the design and optimization of ciliary systems for specific applications.