Fabrication of Liquid Crystal Elastomer Fibers for Actuators, Artificial Muscles and Soft Robots

Liquid crystal elastomer (LCE) is cross-linked network formed by coupling liquid crystal mesogens and polymeric chains. Due to the phase transition of liquid crystals under external stimuli such as heat, light, electricity, magnetic field and chemicals, LCE exhibits anisotropic optical and mechanical properties. Due to its large, reversible deformation and inherent soft elasticity, it has become an excellent material for constructing actuators, artificial muscles and soft robots.<br/>This talk will first introduce the fabrication of LCE fibers developed by the research group, including dry spinning, melt spinning, template method and rotational 3D printing. It will also explicate how to obtain solid and hollow fibers, control their size, structure and liquid crystal orientation. Finally, soft actuators constructed based on LCE fibers achieving various functions are demonstrated. For example, (i) LCE fibers can simulate pumping function of heart muscles and ball shooting of human triceps muscles. (ii) LCE fibers with programmed alignment enriched responsive modes of LCE actuators and have achieved not only common shrinkage and bending deformations, but also developed complex deformations such as elongation, torsion and rotation. (iii) Incorporating liquid metal into LCE fibers can integrate sensing and actuating in a single fiber with a simple design, function as Delta Robot. (iv) Additive manufacturing of LCE actuators based on knitting technology can bring about advanced geometry, integrated multi-functions and efficient recyclability. The porous structure and soft elasticity of LCE knitted actuators will facilitate the development of ergonomic and comfortable wearable devices. Knitted LCE actuators incorporated with other functional fibers and smart textiles can act as a deformable, multifunctional platform.<br/>The above works provide new design concepts for constructing new type of simple, intelligent, and miniaturized soft robots. It can be envisioned that LCE fibers can be potentially applied in fields such as wearable devices, including motion assistance and human computer interactions.<br/><br/>[1] J. Sun, W. Liao, Z. Yang. Additive Manufacturing of Liquid Crystal Elastomer Actuators based on Spinning and Knitting Technology. <i>Adv. Mater.</i> <b>2023</b>,<i> 35</i>, 2302706.<br/>[2] W. Liao, Z. Yang. 3D Printing Programmable Liquid Crystal Elastomer Soft Pneumatic Actuators. <i>Mater. Horiz. </i><b>2023</b>,<i> 10</i>, 576.<br/>[3] Y. Wang, J. Sun, W. Liao, Z. Yang. Liquid Crystal Elastomer Twist Fibers towards Rotating Microengines. <i>Adv. Mater. </i><b>2022</b>,<i> 34</i>, 2107840.<br/>[4] W. Liao, Z. Yang. The Integration of Sensing and Actuating based on a Simple Design Fiber Actuator towards Intelligent Soft Robots. <i>Adv. Mater. Technol. </i><b>2022</b>,<i> 7</i>, 2101260.<br/>[5] Y. Wang,<b>^†</b> W. Liao,<b>^†</b> J. Sun, R. Nandi, Z. Yang. Bioinspired Construction of Artificial Cardiac Muscles Based on Liquid Crystal Elastomer Fibers. <i>Adv. Mater. Technol. </i><b>2022</b>,<i> 7</i>, 2100934.<br/>[6] J. Sun, Y. Wang, W. Liao, Z. Yang. UltraFast, High-Contractile Electrothermal-Driven Liquid Crystal Elastomer Fibers towards Artificial Muscles. <i>Small </i><b>2021</b>,<i> 17</i>, 2103700.