微尺度下锥形微操作探针表面液滴形成的研究

摘要

基于液滴的转移方法可实现微操作任务中微对象的拾取，锥形操作探针则常作为一种毛细力微操作执行工具。主要研究在空气冷凝模式下锥形探针端面的液滴形成。建立了微液滴形成的数学模型，主要包括初始液滴的形成、液滴的合并和液滴的移动，研究了影响操作液滴的关键参数，分析表明：过冷度决定最小液滴半径。对单液滴的生长机制进行理论分析，并通过数值求解的方法模拟了锥形操作探针端面的液滴形成。搭建实验测试平台，实验研究了微尺度下锥形微操作探针端面的液滴形成。实验结果表明：在空气冷凝模式下，操作探针端面能够形成微液滴。经过初始液滴的形成，液滴的合并和移动等过程最终可形成稳定的微液滴，且不同锥顶角下液滴的形成呈现多样化。%The liquid droplet is usually adopted as the vehicle to pick micro-objects during micromanipula-tion tasks,and the conical manipulation probe is constantly employed as the capillary micromanipulation tool. We focus on investigations on water droplet on conical micromanipulation probe during air-cooled condensation. Mathematical models of microdroplet formation,including initial droplet formation,droplets coalescence and droplets motion,were established to analyze critical parameters.Parameter of the degree of subcooling that dominates the minimum radius and the growth rate of individual droplet was theoretically characterized.Ac-cordingly,the process of droplet formation on a conical probe was simulated based on mathematical modeling. Subsequently,extensive experiments,with the assistance of a customized cooling module,were conducted to in-vestigate the droplet formation on conical probes.The experimental results indicate that microdroplets formed on the conical probe during air-cooled condensation.A stable droplet was obtained via initial droplet formation, droplets coalescence and droplets motion.Droplet formation is various because of implementations of conical probe with varied apex angles and shapes,which directly influence the microdroplet formation.