Intelligent Robotics Institute, School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China.
Soft Matter. 2019 Dec 4;15(47):9788-9796. doi: 10.1039/c9sm01966a.
Spiral configurations and helical curlings of plant tendrils and seed pods are very common in nature. Many researchers have tried to develop spirally deformable actuators to mimic these natural spirals through several approaches, such as preforming helical shapes, processing diagonal stripes and employing anisotropic organic layers. However, these methods are usually complex and time-consuming. Here, we used an efficient method to produce a highly oriented carbon nanotube (CNT) film and develop a series of spirally deformable soft actuators which perform various controllable helical actuations. The actuator consists of a CNT layer with strong anisotropy and a silicone layer. By simply adjusting the orientations of the aligned CNTs, the prepared actuators can accomplish left- or right-handed spiral deformations with different helical forms when driven by electricity. Finite element analyses and simulations were conducted to investigate the mechanism. It is confirmed that it is the anisotropic moduli of the CNT film that regulate the internal stress distributions of the actuators and lead to helical actuations. Moreover, complex actuator designs and functional applications were also carried out. A V-shaped actuator can simultaneously achieve left- and right-handed curling with large angles (630°), which vividly imitates the spiral winding of a tendril. A Y-shaped actuator performed three-dimensional movements, which can manipulate lightweight objects deftly. By virtue of easy preparation and flexible function design, the spirally deformable actuators based on the oriented CNT film will be very promising in artificial muscles and bionic soft robots.
植物卷须和豆荚的螺旋结构和螺旋卷曲在自然界中非常常见。许多研究人员试图通过几种方法来开发螺旋变形致动器以模仿这些自然螺旋，例如预成型螺旋形状、加工对角条纹和采用各向异性有机层。然而，这些方法通常很复杂且耗时。在这里，我们使用了一种有效的方法来制备高度取向的碳纳米管 (CNT) 薄膜，并开发了一系列螺旋变形软致动器，这些致动器可实现各种可控的螺旋运动。致动器由具有强各向异性的 CNT 层和硅酮层组成。通过简单地调整取向 CNT 的方向，当用电流驱动时，所制备的致动器可以完成左手或右手螺旋变形，具有不同的螺旋形式。进行了有限元分析和模拟以研究其机制。结果证实，是 CNT 薄膜的各向异性模量调节了致动器的内部应力分布，从而导致了螺旋运动。此外，还进行了复杂的致动器设计和功能应用。V 形致动器可以同时实现大角度（630°）的左右卷曲，生动地模仿了卷须的螺旋缠绕。Y 形致动器进行了三维运动，可以灵巧地操纵轻量级物体。由于易于制备和灵活的功能设计，基于取向 CNT 薄膜的螺旋变形致动器在人工肌肉和仿生软体机器人方面具有广阔的应用前景。
