封闭型与开放型集成的数字微流控芯片中液滴驱动机制与操控研究

In electric-field-mediated digital microfluidics (DMF), there are two distinct architectures - closed systems using parallel-plate electrodes and open systems using coplanar electrodes fabricated on an open substrate. Many envisioned chemical and biological processes in Micro-Total-Analysis-Systems (μTAS) require the combination of both closed and open systems and the ability to move the droplets back and forth between the two. Previous study on closed-and-open integrated DMF systems is quite limited to water droplets under low frequency electric-field actuation. In this project, we provide general theoretical and experimental studies on droplet actuation in such integrated DMF systems. Gibbs surface energy modeling and the method of force balance analysis will be used to investigate droplet actuation mechanism during its transport through the interface between closed and open sections. On-chip droplet actuation will be demonstrated to test the theoretical predictions. To optimize the chip design, we use a beveled edge at the closed and open interface to facilitate droplet detachment, and develop an integrated chip with separable open sections. High-performance oleophobic surfaces will be fabricated and used in integrated DMF chips for simultaneous actuation of both water and oil droplets. The theoretical modeling and experimental results in this project will be helpful to improve our understanding of the integrated DMF chip in its actuation mechanism and actuation performances. This study is of important significances to further applications of integrated DMF chips in multifunctional complex μTAS systems.

基于电场驱动的数字微流控（Digital Microfluidics，简称DMF）芯片有封闭型和开放型两种基本构型，多功能自动化芯片微全分析系统的发展要求新型DMF芯片兼具这两种芯片构型的优点。以往对这种封闭区开放区集成芯片的研究局限于水滴在低频电场下的驱动，不具有普适性。本项目针对集成芯片上的液滴驱动与控制开展通用性的深入研究。通过建立普适性的力学分析模型和吉布斯表面能模型，探讨各种液滴在封闭区开放区界面上的驱动机制。实验研究液滴的片上运动特性，验证理论模型的结果。优化芯片设计，利用倒角界面减小液滴的粘附效应，研究开放区可分离的接触式集成芯片。制备疏油表面，开发可用于水油液滴共片驱动的集成芯片。本项目对多种液滴在集成芯片上驱动控制的理论和实验研究，将有助于增进液滴驱动机制的理解，提高集成芯片中液滴驱动可靠性，促进集成芯片在自动控制的多功能微全分析系统中的应用。

本研究针对传统数字微流控芯片的各自分立的两种基本构型——平行双基板的封闭型和平面单基板的开放型，研究统一两种构型的集成化芯片，以综合这两种芯片构型的优点，使数字微流控芯片更好的适应多功能自动化芯片微全分析系统的发展要求。本研究的重点是集成芯片上的液滴驱动与控制，特别是开展液滴在集成芯片界面通过性上的深入研究。通过建立液滴在不同构型和界面位置上的吉布斯表面能模型，考察液滴在界面上运动中的体系表面能变化，分析液滴的运动趋势和稳定位置。建立了液滴在界面运动过程中的普适性力学分析模型，根据液滴的受力平衡确定液滴穿过封闭区开放区界面的驱动条件。实验研究了液滴的片上运动特性，验证了理论模型的结果。对于芯片结构进行了优化设计，利用倒角界面减小液滴的粘附效应。本研究开创性的研究了油滴在集成芯片上的运动特性，通过制备疏油表面，开发了油滴在集成芯片上稳定驱动方法。本研究所开展的对于多种液滴在集成芯片上驱动控制的理论和实验研究，揭示了液滴在集成芯片界面上的驱动机制，提高了集成芯片中液滴驱动可靠性。本研究的结果拓宽了数字微流控芯片的应用范围，增进了数字微流控芯片的驱动自动化程度，对推动数字微流控技术在生物传感、医学检测等领域的应用有重要意义。