Janus球形微马达的自驱动机理研究:自扩散泳动与微气泡推进

发布时间：2018-03-12 11:46

本文选题：微纳马达　切入点：Janus微球　出处：《科学通报》2017年Z1期 　论文类型：期刊论文

【摘要】：微纳马达的研究是一个多学科交叉的新兴领域.其中,Janus微马达利用自身两面异性导致的局部梯度场而产生自驱动现象,引起了学界的普遍关注.本文主要基于目前已开展的工作并借鉴国内外的一些最新成果,以期对Janus球形微马达的物理特征给出全面的描述.针对铂-二氧化硅(Pt-SiO_2)型Janus微球在过氧化氢溶液中发生的自驱动,通过实验和数值模拟分析了其两种自驱动形式(自扩散泳动和微气泡推进)的物理机制和运动特征.直径小于5mm的Janus微球发生自扩散泳动,通过无量纲均方位移随时间的变化揭示了微球平动经历由纯布朗运动、扩散泳动到类布朗运动的过程,给出了特征时间及不同阶段的主导物理因素.位移概率分布可以表征非高斯性,并分析布朗力矩主导的旋转特性并讨论壁面限制及剪切流的影响.直径20~50mm微球可观测到微气泡推进,微球位移揭示了随气泡尺寸增长,微球经过自扩散泳、气泡生长和气泡溃灭推进3个阶段组成的周期运动.Rayleigh-Plesset(R-P)方程则揭示了依次由黏性力、表面张力及气泡周围流体压力控制下的气泡生长标度率.本文还从应用角度介绍了交变电场下,利用介电泳操控Janus微球的微穿梭输运(microshuttle)技术,并讨论了自扩散泳与自电泳差别及微气泡推进型微马达效率提高等问题.
[Abstract]:The research of micro / nano motors is a new and interdisciplinary field, in which Janus micro motors make use of the local gradient field caused by their two faces to produce self driving phenomenon. This paper is mainly based on the work that has been carried out and draws on some latest achievements at home and abroad. In order to give a comprehensive description of the physical characteristics of Janus spherical micromotors, the self-actuation of platinum-silica Pt-SiO2) Janus microspheres in hydrogen peroxide solution was studied. The physical mechanism and motion characteristics of two self-driving forms (self-diffusion swimming and micro-bubble propulsion) are analyzed by experiment and numerical simulation. Self-diffusion swimming occurs in Janus microspheres with diameter less than 5 mm. Through the change of dimensionless mean square displacement with time, it is revealed that the translational movement of microspheres has experienced the process from pure Brownian motion, diffusion swimming motion to Brownian motion. The characteristic time and the dominant physical factors in different stages are given. The rotation characteristics dominated by Brownian moment are analyzed and the effects of wall limitation and shear flow are discussed. The microbubble propulsion can be observed by the diameter of 20 ~ 50mm microspheres. The displacement of the microspheres reveals that the microspheres go through self-diffusion swimming with the increase of bubble size. The periodic motion. Rayleigh-PlessetSet R-P equation of bubble growth and bubble collapse and propulsion reveals that the viscosity force is the main component of the equation. Surface tension and bubble growth scaling rate controlled by fluid pressure around bubbles. This paper also introduces the microshuttletechnology of Janus microspheres controlled by dielectric electrophoresis under alternating electric field from the point of view of application. The difference between self diffusion and self-electrophoretic and the improvement of efficiency of micro-bubble propulsion micromotor are discussed.
【作者单位】：中国科学院力学研究所非线性力学国家重点实验室(LNM);西安建筑科技大学环境与市政工程学院;
【基金】：国家自然科学基金(11572335,11272322) 西安建筑科技大学创新团队资助
【分类号】：TB383.1

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