Wang Shiyu, Li Shucong, Zhao Wenchang, Zhou Ying, Wang Liqiu, Aizenberg Joanna, Zhu Pingan
Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China.
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
Lab Chip. 2024 Aug 20;24(17):4073-4084. doi: 10.1039/d4lc00369a.
Microactuators, capable of executing tasks typically repetitive, hazardous, or impossible for humans, hold great promise across fields such as precision medicine, environmental remediation, and swarm intelligence. However, intricate motions of microactuators normally require high complexity in design, making it increasingly challenging to realize at small scales using existing fabrication techniques. Taking inspiration from the hierarchical-anisotropy principle found in nature, we program liquid crystalline elastomer (LCE) microactuators with multimodal actuation tailored to their molecular, shape, and architectural anisotropies at (sub)nanometer, micrometer, and (sub)millimeter scales, respectively. Our strategy enables diverse deformations with individual LCE microstructures, including expanding, contracting, twisting, bending, and unwinding, as well as re-programmable shape transformations of assembled LCE architectures with negative Poisson's ratios, locally adjustable actuation, and changing from two-dimensional (2D) to three-dimensional (3D) structures. Furthermore, we design tetrahedral microactuators with well-controlled mobility and precise manipulation of both solids and liquids in various environments. This study provides a paradigm shift in the development of microactuators, unlocking a vast array of complexities achievable through manipulation at each hierarchical level of anisotropy.
微致动器能够执行通常对人类来说重复、危险或不可能完成的任务，在精准医学、环境修复和群体智能等领域具有巨大潜力。然而，微致动器的复杂运动通常需要高度复杂的设计，这使得使用现有制造技术在小尺度上实现变得越来越具有挑战性。从自然界中发现的层级各向异性原理中获得灵感，我们分别针对液晶弹性体（LCE）微致动器在（亚）纳米、微米和（亚）毫米尺度上的分子、形状和结构各向异性，对其进行多模态驱动编程。我们的策略能够使单个LCE微结构实现多种变形，包括膨胀、收缩、扭曲、弯曲和展开，以及具有负泊松比、局部可调驱动并能从二维（2D）转变为三维（3D）结构的组装LCE架构的可重新编程形状变换。此外，我们设计了具有良好可控移动性且能在各种环境中对固体和液体进行精确操纵的四面体微致动器。这项研究为微致动器的发展带来了范式转变，开启了通过在各层级各向异性水平上进行操纵可实现的大量复杂性。
