疏水表面冷凝的毛细力微操作液滴动态分配

Dynamic distribution of capillary microdroplet using water condensation on hydrophobic surface

摘要:

为实现毛细力操作液滴获取，提出基于疏水表面冷凝的毛细力微操作液滴分配方法，研究微对象转移进程中(拾取-释放)所需的操作液滴条件. 针对操作液滴分配任务，建立液桥拉伸进程中的模型. 基于VOF(volume of fluid)方法，建立平面-平面、平面-球面配置模式下的动态模型，分析操作液滴的动态获取过程. 仿真结果表明：接触角和提升速度均对辅助液滴的获取率和断裂距离起到重要作用，液滴趋向于接触角小的端面，提升速度可促使液滴在两平面均分. 液桥体积对辅助液滴获取率的影响较小，液桥断裂距离与液桥体积成正比变化. 实验研究了平面-平面、平面-球面配置下的操作液滴动态分配进程，验证了所提出方法的可行性.

Abstract:

A microdroplet distribution method based on water condensation on hydrophobic surface is presented to obtain micromanipulation droplet for capillary gripping. Accordingly, the droplet condition required in micro-objects transfer (pick-and-place) is investigated. Model of liquid bridge stretching is established during microdroplet dispensing. Two configurations (plane-plane, plane-sphere) of dynamic liquid bridge is modeled using VOF (Volume of Fluid) method to analyze the acquisition process of capillary micromanipulation droplet. Simulation results demonstrate that the contact angle and drawing velocity have a significant influence on the acquisition fraction of auxiliary droplet and rupture distance. The initial liquid bridge moves toward the surface with small contact angle after the formed liquid bridge rupture. Micromanipulation probes with big drawing velocity enable manipulation droplet to split on two surfaces equally. The impact of droplet volume on the acquisition fraction of auxiliary droplet is relatively small, but is proportional to the rupture distance. Configurations (plane-plane, plane-sphere) of dynamic liquid bridge are experimental investigated to verify feasibility of the proposed method.