Li Qi, Liang Tengfei, Ye Wenjing
Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong.
Phys Rev E Stat Nonlin Soft Matter Phys. 2014 Sep;90(3):033009. doi: 10.1103/PhysRevE.90.033009. Epub 2014 Sep 16.
Thermally induced mechanical loading has been shown to have significant effects on micro- and nano-objects immersed in a gas with a nonuniform temperature field. While the majority of existing studies and related applications focus on forces, we investigate the torque, and thus the rotational motion, produced by such a mechanism. Our study has found that a torque can be induced if the configuration of the system is asymmetric. In addition, both the magnitude and the direction of the torque depend highly on the system configuration, indicating the possibility of manipulating the rotational motion via geometrical design. Based on this feature, two types of rotational micromotor that are of practical importance, namely pendulum motor and unidirectional motor, are designed. The magnitude of the torque at Kn=0.5 can reach to around 2nN×μm for a rectangular microbeam with a length of 100μm.
热致机械载荷已被证明对浸没在具有非均匀温度场的气体中的微纳物体有显著影响。虽然现有的大多数研究和相关应用都集中在力上，但我们研究了这种机制产生的扭矩，进而研究了旋转运动。我们的研究发现，如果系统配置不对称，就会产生扭矩。此外，扭矩的大小和方向都高度依赖于系统配置，这表明通过几何设计来操纵旋转运动是可能的。基于这一特性，设计了两种具有实际重要性的旋转微电机，即摆式电机和单向电机。对于长度为100μm的矩形微梁，在Kn = 0.5时扭矩大小可达到约2nN×μm。
