Printing ferromagnetic domains for untethered fast-transforming soft materials
Printing ferromagnetic domains for untethered fast-transforming soft materials
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DOI：
10.1038/s41586-018-0185-0
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发表时间：
2018-06-14
期刊：
影响因子：
64.8
通讯作者：
Zhao, Xuanhe
中科院分区：
文献类型：
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作者：
Kim, Yoonho;Yuk, Hyunwoo;Zhao, Xuanhe
能够响应于诸如光、热、溶剂、电场和磁场的刺激而在三维（3D）形状之间转换的软材料在诸如柔性电子（1，2）、软机器人（3，4）和生物医学（5-7）的不同领域中有应用。特别是，磁场为生物医学应用提供了一种安全有效的操作方法，这通常需要在封闭和受限的空间中进行远程驱动（8-10）。随着磁场控制的进步，磁响应软材料也从嵌入离散磁体（12）或将磁性颗粒（13）结合到软化合物中发展到在聚合物片材（14，15）中产生不均匀的磁化分布。在这里，我们报告了软材料中编程铁磁畴的3D打印，通过磁致动实现复杂3D形状之间的快速转换。我们的方法是基于含有铁磁微粒的弹性体复合材料的直接墨水书写（16）。通过在打印时向分配喷嘴施加磁场（17），我们使颗粒沿着所施加的场重新取向，以将图案化的磁极性赋予打印的细丝。这种方法使我们能够在复杂的3D打印软材料中对铁磁畴进行编程，从而实现一系列以前无法实现的转换模式，例如具有负泊松比的机械超材料的远程控制拉胀行为。我们具有编程铁磁畴的印刷软材料的致动速度和功率密度比现有的3D打印活性材料大几个数量级。我们进一步展示了从复杂的形状变化中获得的各种功能，包括可重新配置的软电子器件，可以跳跃的机械超材料和爬行，滚动，捕捉快速移动的物体和运输药物剂量的软机器人。
Soft materials capable of transforming between three-dimensional (3D) shapes in response to stimuli such as light, heat, solvent, electric and magnetic fields have applications in diverse areas such as flexible electronics(1,2), soft robotics(3,4) and biomedicine(5-7). In particular, magnetic fields offer a safe and effective manipulation method for biomedical applications, which typically require remote actuation in enclosed and confined spaces(8-10). With advances in magnetic field control11, magnetically responsive soft materials have also evolved from embedding discrete magnets(12) or incorporating magnetic particles(13) into soft compounds to generating nonuniform magnetization profiles in polymeric sheets(14,15). Here we report 3D printing of programmed ferromagnetic domains in soft materials that enable fast transformations between complex 3D shapes via magnetic actuation. Our approach is based on direct ink writing(16) of an elastomer composite containing ferromagnetic microparticles. By applying a magnetic field to the dispensing nozzle while printing(17), we reorient particles along the applied field to impart patterned magnetic polarity to printed filaments. This method allows us to program ferromagnetic domains in complex 3D-printed soft materials, enabling a set of previously inaccessible modes of transformation, such as remotely controlled auxetic behaviours of mechanical metamaterials with negative Poisson's ratios. The actuation speed and power density of our printed soft materials with programmed ferromagnetic domains are orders of magnitude greater than existing 3D-printed active materials. We further demonstrate diverse functions derived from complex shape changes, including reconfigurable soft electronics, a mechanical metamaterial that can jump and a soft robot that crawls, rolls, catches fast-moving objects and transports a pharmaceutical dose.