Liquid crystal elastomers (LCEs) are a class of stimuli-responsive polymers that undergo reversible shape-change in response to environmental changes. The shape change of LCEs can be programmed during processing by orienting the liquid crystal phase prior to crosslinking. The suite of processing techniques that has been developed has resulted in a myriad of LCEs with different shape-changing behavior and mechanical properties. Aligning LCEs via mechanical straining yields large uniaxial actuators capable of a moderate force output. Magnetic fields are utilized to control the alignment within LCE microstructures. The generation of out-of-plane deformations such as bending, twisting, and coning is enabled by surface alignment techniques within thin films. 4D printing processes have emerged that enable the fabrication of centimeter-scale, 3D LCE structures with a complex alignment. The processing technique also determines, to a large extent, the potential applications of the LCE. For example, 4D printing enables the fabrication of LCE actuators capable of replicating the forces generated by human muscles. Employing surface alignment techniques, LCE films can be designed for use as coatings or as substrates for stretchable electronics. The growth of new processes and strategies opens and strengthens the path for LCEs to be applicable within biomedical device designs.

中文翻译：

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液晶弹性体的加工进步为生物医学应用开辟了道路

液晶弹性体 (LCE) 是一类刺激响应聚合物，可响应环境变化而发生可逆的形状变化。通过在交联之前定向液晶相，可以在加工过程中对 LCE 的形状变化进行编程。已开发的一套加工技术产生了无数具有不同形状变化行为和机械性能的 LCE。通过机械应变对齐 LCE 产生能够输出中等力的大型单轴致动器。磁场用于控制 LCE 微结构内的排列。通过薄膜内的表面对齐技术，可以产生平面外变形，例如弯曲、扭曲和锥形。4D 打印工艺已经出现，可以制造厘米级、具有复杂对齐的 3D LCE 结构。处理技术也在很大程度上决定了 LCE 的潜在应用。例如，4D 打印能够制造能够复制人体肌肉产生的力的 LCE 执行器。采用表面对齐技术，LCE 薄膜可设计用作涂层或可拉伸电子设备的基板。新流程和策略的发展开辟并加强了 LCE 在生物医学设备设计中适用的途径。LCE 薄膜可设计用作涂层或可拉伸电子产品的基材。新流程和策略的发展开辟并加强了 LCE 在生物医学设备设计中的适用路径。LCE 薄膜可设计用作涂层或可拉伸电子产品的基材。新流程和策略的发展开辟并加强了 LCE 在生物医学设备设计中适用的途径。