光热效应操控双重乳液的热质传输特性及界面行为

Microfluidic chip based on photothermal effect has received extensive attention due to the advantages of simple system and easy manipulation. The manipulation of double emulsion based on photothermal effect is a complex process involving flow, heat/mass transfer and interface dynamic behavior of microfluid, light propagation and photothermal effect. The heat/mass transfer characteristics, dynamic interface behavior of microfluid plays an important role in its performance. The project aims at double emulsion manipulated by the photothermal effect of laser to study the characteristics of heat and mass transfer and dynamic interface behavior coupled with the light propagation and photothermal effect using the visual and numerical investigation. Firstly, the research will be focused at the characteristics of heat transfer and Marangoni flow of double emulsion when the laser is focused at the center of double emulsion. Based on this, the characteristics of dynamic interface behavior, Marangoni flow and heat transfer induced by the photothermal effect focused at off-center of double emulsion will be investigated. At last, the dynamic interface behavior, Marangoni flow and heat/mass transfer characteristics of the interface reconstruction process caused by photothermal effect will be investigated. With the above research results, the heat/mass transfer and dynamic interface behaviors, and the impact of various design and operating parameters on the performance of photothermal effect based manipulation of double emulsion will be revealed, which will provide the guidance for optimizing the design and operation of this new technology. The outcome will also lay a solid foundation for the development of double emulsion based microfluidics.

基于光热效应的微流控芯片由于具有系统简单、易精确操控等优点，已引起人们的广泛关注。基于光热效应的双重乳液操控是一个涉及微流体的流动、传热传质、界面行为和光传播及光热效应相耦合的复杂过程，热质传输和界面行为对其性能有着重要影响。本项目以光热效应操控双重乳液为对象，围绕光热效应操控双重乳液中，耦合光传播和光热效应的热质传输特性及界面行为这一关键问题开展可视化实验和数值模拟研究。首先，研究光热效应中心加热双重乳液的传热及马兰戈尼流动特性；在此基础上，研究光热效应偏心加热双重乳液的界面行为、马兰戈尼流动及传热特性；最后，研究光热效应诱导界面重构行为、马兰戈尼流动及热质传输特性。通过上述研究，揭示光热效应操控双重乳液的热质传输特性与界面行为及各操控运行参数的影响规律。促进微流控芯片技术的发展，为微流控芯片的中的双重乳液应用开发奠定理论基础。

基于光热效应的微流控芯片具有系统简单、易精确操控等优点，得到了广泛关注。双重乳液由于独特的壳核结构在微流控芯片中具有广泛的应用前景，基于光热效应的双重乳液操控是一个涉及微流体流动、传热传质、界面行为相耦合的复杂过程，热质传输和界面行为是其功能实现和性能保障的关键。本项目提出利用光热效应来操控双重乳液，围绕着光热效应操控双重乳液中的热质传输特性和界面行为这一关键问题开展实验和数值模拟研究。首先研究了光热效应中心加热乳液的传热和马兰戈尼流动特性，获得了光热效应中心加热乳液的温度分布特性和流动规律，建立了光热效应中心加热乳液的温升表达式，并应用该表达式实现PCR的温度循环。其次，针对双重乳液的双界面相互作用，研究了微流道内双重乳液的双界面行为特性；揭示内液滴聚合诱导双重乳液的内外界面行为相互影响机理，获得内液滴聚合诱导外界面变形的表达式；明晰了双重乳液中内液滴存在对双重乳液生产特性的影响规律；揭示双重乳液内外界面聚合诱导内液滴释放的特性，发现内液滴释放存在四种释放类型——一次释放、部分释放、同侧两次释放、两侧依次释放。再次，研究了温差驱动单重乳液的迁移特性，获得了温差诱导热毛细流动驱动单重乳液迁移的影响规律。在此基础，提出利用激光光热效应诱导热毛细流动实现对双重乳液的精确操控；研究了热毛细流动诱导内液滴释放特性，发现内液滴释放存在四种释放类型；探究热毛细流动诱导双重乳液聚合特性，明晰了内液滴存在对外界重构的影响规律；模拟研究了三相不互溶双重乳液在热毛细流动驱动的双重乳液迁移特性；分析总结了光热效应诱导双重乳液界面重构、Marangoni 流动及传热传质耦合规律。项目研究促进微流控芯片技术的发展，为微流控芯片的中的双重乳液应用开发奠定理论基础。