Materials Science and Engineering Program , University of California, San Diego , La Jolla , California 92093 , United States.
Department of Civil Engineering , Anhui Jianzhu University , Hefei , Anhui 230601 , China.
ACS Appl Mater Interfaces. 2018 Aug 1;10(30):25689-25696. doi: 10.1021/acsami.8b07563. Epub 2018 Jul 23.
Specially arranged external stimuli or carefully designed geometry are often essential for realizing continuous autonomous motion of active structures without self-carried power. As a consequence, it is usually very challenging to further integrate those structures as active building blocks into a system with a complex form and multiple functions. In this letter, we report an autonomous motion of a surprisingly simple setup: a cylindrical elastomer rod on a flat hot surface or under homogeneous illumination of visible light. We further show that the rod can roll continuously without any sign of a pause after 6 h, if an obstacle is put in front of it. We demonstrate that such nonintuitive autonomous rolling results from a combination of large thermal actuation of the elastomer and heat transfer between the rod and its surroundings. Quantitative predictions of the rolling speed from the developed thermomechanics model agree reasonably well with experimental measurements. Using the autonomous rolling rods as main building blocks, we further design and fabricate a light-powered vehicle and a thermally powered conveyor for mass transport in both air and water environments.
特别设计的外部刺激或精心设计的几何形状通常对于实现无自携动力的主动结构的连续自主运动至关重要。因此，通常非常具有挑战性的是，将这些结构进一步集成作为主动构建块到具有复杂形式和多种功能的系统中。在这封信中，我们报告了一个非常简单的设置的自主运动：一个圆柱形的弹性体棒在一个平坦的热表面上或在可见光的均匀照射下。我们进一步表明，如果在它前面放置一个障碍物，棒可以在 6 小时后继续连续滚动，没有任何停顿的迹象。我们证明，这种非直观的自主滚动是由于弹性体的大热致动和棒与其周围环境之间的热传递的组合产生的。从开发的热机械模型得出的滚动速度的定量预测与实验测量相当吻合。使用自主滚动棒作为主要构建块，我们进一步设计和制造了一个光动力车辆和一个热动力输送机，用于在空气和水环境中的质量运输。
