基于激光诱导的微/小物体气-液界面表面张力驱动机理研究

The principle of laser-induced surface tension driven locomotion of micro/mini objects at gas-liquid interfaces possesses great potential application prospect in various research areas such as micro-operation, experiments in physical chemistry and bioengineering, due to the advantages of low damage and pollution, high efficiency, and easy to realize selective manipulation of single objects both in macro and micro scales. Presently, there is still lack of quantitative understanding of the underlining mechanism of laser-induced surface tension driven locomotion and the relevant scale effects. This research focuses on this issue by combing theoretical, numerical and experimental methods, and the object size of from sub-centimeter scale to sub-millimeter scale is considered. First, mathematical models for the forces caused by laser-induced surface tension difference and thermos-capillary convection are established respectively with numerical simulation methods, and both the surface tension effects and influence of object size on the liquid-object interactions are investigated. Then, dynamical models are built to analyze the liquid-surface motion of objects, and mathematical models are established for the laser-induced surface tension driven locomotion of micro/mini objects at gas-liquid interfaces. Finally, experiments on the gas-liquid motion of different-material objects with different size are carried out to validate the mathematical models. This research will provide both theoretical basis and technology supports for the development of multi-scale gas-liquid-interface manipulation techniques in future.

基于激光诱导的微/小物体气-液界面表面张力驱动，具有非接触式损伤与污染小、易实现选择性目标与跨尺度宏微驱动、驱动效率高等优点，在微操作、化学物理实验、生物工程等领域具有广阔的应用前景。针对目前在激光诱导作用下的表面张力作用机制、物体液面运动规律以及受物体尺度的影响等方面缺乏定量认识的问题，本项目面向亚厘米级至亚毫米级尺度物体，综合理论、数值与实验方法，致力于阐明激光诱导作用下的物体气-液界面运动机理：基于数值模拟方法，建立激光诱导作用下的表面张力差、热毛细对流对物体作用计算模型，揭示表面张力作用机制及其受物体尺度的影响规律；基于动力学建模分析，揭示不同尺度物体的液面运动规律，建立基于激光诱导的微/小物体气-液界面表面张力驱动计算模型；通过开展不同材料、尺度物体在不同液面上的激光诱导运动实验，对理论计算模型进行验证，为今后开发基于激光诱导的跨尺度气-液界面宏微操作技术奠定理论基础和技术支撑。

快速发展的材料、生物、化工等技术，对同一环境下实现操作对象及操作尺度多样化的功能需求不断增加，开展低损伤高效的跨尺度微操作技术研究具有重要意义。本研究基于Marangoni及光热效应，综合理论、数值与实验方法，开展了基于激光诱导的微/小物体气－液界面表面张力驱动机理研究，分析了激光照射下的物体-液体间多种作用力及其耦合机制，推导建立了理论模型，得到了光斑属性、物体材料及尺度、流体介质等因素的影响规律，提出了利用环形激光光斑在液面诱导环形势阱，借助表面张力实现微小物体液面捕获及操作的新方法，并研制出了试验原理样机，实现了手动、自动液面微操作。该方法相比光镊技术，将操作力及尺度拓展至毫牛及毫米级，可实现微米级到毫米级的跨尺度微操作，为开发低损伤高效的液面跨尺度微操作技术与搭建“Lab on liquid film”、“Lab on droplet”等开辟了新的思路，在微操作、微组装、化学物理实验以及生物工程等领域具有广阔的应用前景。