基于SLIPS极性低压电润湿的液滴三维操控与驱动机理研究

In order to solve the problems, such as high driving voltage, detachment of hydrophobic layer and high-voltage breakdown of the dielectric layer, which exist in droplet manipulation based on electrowetting-on-solid-dielectric, this project intends to use fluoroalkyl silane-modified slippery liquid infused porous surface (FAS-SLIPS) as a whole dielectric-hydrophobic layer, by utilizing the unique polarity-dependent low-voltage electrowetting of this flexible thin-film to realize low direct current voltage (5-30V) droplet manipulation. Firstly, the change of thin-film surface microstructure (shape characteristic and redistribution of FAS single-monolayer) and the relationship between physical proprieties and electrowetting characteristic of FAS-SLIPS are studied, the FAS-SLIPS thin-film parameters with excellent electrowetting performances ( driving threshold voltage is 3V and the response speed is 20ms) are obtained. Then, the influences of the electrode (structure, size and layout) and driving voltage on droplet three-dimensional manipulation (creating, transporting, merging on inclined and declined surfaces , jumping between two surfaces) performances are studied with simulation and experiment methods, several of novel electrode structures for each manipulation functions are proposed and the driving conditions are obtained. Finally, the droplet manipulation theory model is established, and its internal driving mechanism of polarity-dependent low-voltage electrowetting is found by analyzing the thin-film characterizations. This project will provide new ideas for developing compact, low-voltage driving and high-performance droplet microfluidic devices, and also provide a theoretical foundation for its application in lab-on-chip and others.

为解决固体介质层电润湿液滴操控存在的驱动电压高、疏水层易脱落及介质层高压易击穿等问题，本项目拟以氟硅烷修饰光滑注液多孔表面（FAS-SLIPS）为介质-疏水一体层，利用该柔性薄膜特有的极性低压电润湿特性实现低电压（5-30V）液滴三维操控。研究外电压作用下薄膜界面微观结构（形貌结构、氟硅烷单分子层排布）变化规律及薄膜物理参量对电润湿特性的影响规律，获得3V低门限电压与20ms快响应的最佳薄膜参数；理论与实验结合研究电极结构（形状、尺寸与布局）、驱动电压对液滴三维操控（倾斜平面及弯曲面上的产生、运输与融合；两分离面间的弹跳）性能的影响规律，获得适合FAS-SLIPS电润湿液滴各操控功能的新型电极结构与驱动条件；建立液滴操控理论模型，结合表征揭示极性低压电润湿液滴驱动内在机理。该项目的开展将为发展低压驱动、结构紧凑、性能优异的液滴三维操控芯片提供新思路，为在芯片实验室等上的应用奠定理论基础。

基于介电润湿效应的数字微流控技术因其控制方式灵活、高效节能、结构简单及功能全面等优势，已在芯片实验室生物化学分析等应用领域引起了国内外科学界极高关注。本项目以氟硅烷修饰光滑注液多孔表面（FAS-SLIPS）为介质-疏水一体层，利用该柔性薄膜特有的极性低压电润湿特性实现数字微液滴操控。研究了SLIPS液滴动态电润湿行为，获得了外加电压、硅油粘度和油层厚度对动态电润湿行为的影响规律，建立了描述液滴在外电压作用下扩散过程的数学动力模型。研究了液滴在共面电极之间的二维操控。获得了电极结构、电压大小、极性与液滴驱动之间的关系，并实现了开放平面芯片上的多液滴操控。基于平行阵列电极结构系统实现液滴三维操控，获得了垂直方向静电力与水平方向电润湿力驱动液滴的条件，并建立了液滴垂直运动的动态传输模型。研究发现对两种力而言，液滴始终从高电位电极向低电位电极移动。该项目的顺利开展为制造快速响应、低压驱动、抗高压击穿、性能优异的新型柔性基底电润湿液滴三维操控芯片奠定基础，其在柔性电润湿显示屏、光流体器件及微全分析系统等领域均有一定实际应用价值与潜力。