Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093, USA.
Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093, USA.
Sci Robot. 2021 Aug 25;6(57). doi: 10.1126/scirobotics.abi9704.
Fibers capable of generating axial contraction are commonly seen in nature and engineering applications. Despite the broad applications of fiber actuators, it is still very challenging to fabricate fiber actuators with combined large actuation strain, fast response speed, and high power density. Here, we report the fabrication of a liquid crystal elastomer (LCE) microfiber actuators using a facile electrospinning technique. Owing to the extremely small size of the LCE microfibers, they can generate large actuation strain (~60 percent) with a fast response speed (<0.2 second) and a high power density (400 watts per kilogram), resulting from the nematic-isotropic phase transition of liquid crystal mesogens. Moreover, no performance degradation is detected in the LCE microfibers after 10 cycles of loading and unloading with the maximum strain of 20 percent at high temperature (90 degree Celsius). The small diameter of the LCE microfiber also results in a self-oscillatory behavior in a steady temperature field. In addition, with a polydopamine coating layer, the actuation of the electrospun LCE microfiber can be precisely and remotely controlled by a near-infrared laser through photothermal effect. Using the electrospun LCE microfiber actuator, we have successfully constructed a microtweezer, a microrobot, and a light-powered microfluidic pump.
能够产生轴向收缩的纤维在自然界和工程应用中很常见。尽管纤维致动器有广泛的应用，但制造具有综合大致动应变、快速响应速度和高功率密度的纤维致动器仍然非常具有挑战性。在这里，我们报告了使用简便的静电纺丝技术制造液晶弹性体（LCE）微纤维致动器。由于 LCE 微纤维的极小尺寸，它们可以在快速响应速度（<0.2 秒）和高功率密度（400 瓦/千克）下产生大的致动应变（~60%），这是由于液晶介晶的向列-各向同性相转变。此外，在高温（90 摄氏度）下以 20%的最大应变进行 10 次加载和卸载循环后，LCE 微纤维没有检测到性能下降。LCE 微纤维的小直径也导致在稳定温度场中产生自振荡行为。此外，通过聚多巴胺涂层，通过光热效应，电纺 LCE 微纤维的致动可以通过近红外激光进行精确和远程控制。使用电纺 LCE 微纤维致动器，我们成功构建了微镊子、微型机器人和光动力微流泵。
