Ni Ke, Peng Qi, Gao Enlai, Wang Kun, Shao Qian, Huang Houbing, Xue Longjian, Wang Zhengzhi
Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan, Hubei 430072, China.
Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China.
ACS Nano. 2021 Mar 23;15(3):4747-4758. doi: 10.1021/acsnano.0c09298. Epub 2021 Feb 22.
Stimuli-responsive micro/nanostructures that exhibit not only programmable but also reprogrammable actuation behaviors are highly desirable for various advanced engineering applications (.., anticounterfeiting, information encoding, dynamic imaging and display, microrobotics, ) but yet to be realized with state-of-the-art technologies. Here we report a concept and a corresponding experimental technique for core-shell magnetic micropillars enabling simultaneously programmable and reprogrammable actuations using a simple magnetic field. The micropillars are composed of elastomeric hollow shells for shaping encapsulated with liquid magnetic nanocomposite resin cores for actuating. The spatial distribution of the magnetic nanoparticles inside the resin channels can be dynamically modulated within individual micropillars, which consequently regulates the magnetomechanical responses of the pillars upon actuation (bending deformation varied near 1 order of magnitude under the same actuation field). We demonstrate that the micropillars with contrasting bending responses can be configured in an arbitrary spatial pattern by direct magnetic writing, and the written pattern can then be easily magnetically erased to facilitate next-round rewriting and reconfiguration. This reprogrammable actuation capability of the micropillars is further demonstrated by their potential applications for rewritable paper and recyclable displays, where various microscale characteristics can be controlled to dynamically appear and disappear at the same or different locations of one single micropillar array. The core-shell magnetic micropillars reported here provide a universal prototype for reprogrammable responsive micro/nanostructures through rational design and facile fabrication from conventional materials.
对于各种先进工程应用（如防伪、信息编码、动态成像与显示、微型机器人技术等）而言，不仅具有可编程而且具有可重新编程驱动行为的刺激响应性微/纳米结构是非常理想的，但利用现有技术尚未实现。在此，我们报告了一种概念及相应的实验技术，用于核壳磁性微柱，其能够使用简单磁场同时实现可编程和可重新编程的驱动。这些微柱由用于成型的弹性体空心壳和用于驱动的液体磁性纳米复合树脂芯组成。树脂通道内磁性纳米颗粒的空间分布可在单个微柱内动态调制，从而在驱动时调节微柱的磁机械响应（在相同驱动场下弯曲变形变化近1个数量级）。我们证明，具有对比弯曲响应的微柱可通过直接磁写入以任意空间模式配置，然后可轻松擦除写入的图案以利于下一轮重写和重新配置。微柱的这种可重新编程驱动能力通过其在可重写纸张和可回收显示器方面的潜在应用得到进一步证明，其中各种微尺度特征可被控制在单个微柱阵列的相同或不同位置动态出现和消失。本文报道的核壳磁性微柱通过合理设计和使用常规材料的简便制造方法，为可重新编程的响应性微/纳米结构提供了一个通用原型。
