微流控器件仿生密封机理研究

The micro surface structure of several aquatic plants and animals, such as Salvinia molesta, are studied as bionic prototype and a novel sealing method in micro scale based on the interface system founded by the bio-inspired micro structure and the gas/liquid or liquid/liquid interface is proposed. With the investigation of influence of the bio-inspired micro structure on the stability of the gas/liquid and liquid/liquid interface in flow, the bearing modes and mechanism of stability of the interface are reveled. Effects of the geometries, wettability and the elasticity of the micro structure are studied. Then the instability of the interface subjected to several kinds of loads, including the pressure differential, the shear, and so on, is investigated to reveal the condition of instability and the styles of failure. On this basis, the physical model of the dynamic behavior of the interface is build, and the bearing capability of the bionic interface is evaluated. The design theory of the bio-inspired seal is proposed. In addition, the drag , heat and mass exchange capability of the microfluidic device with the newly designed bio-inspired seal are studied. A comprehensive design method are finally build taking all of the factors mentioned into account. Ultimately, the mechanism of the dynamic behavior of the gas/liquid and liquid/liquid interfaced affected by the bionic micro structure is clarified and the bio-inspired seal is developed. The results could serves as the theoretical basis and technical manners to solve the problem concerning the dynamic sealing of microfluidic devices.

本课题以槐叶萍等水生动植物为原型，提出利用仿生表面微结构与气/液或液/液界面共同构筑功能界面系统以实现微尺度的动态密封。通过研究流动状态下仿生微结构的几何形状、亲疏水性、变形能力等性状的各种组合对气/液和液/液界面稳定性的影响，揭示界面的承载模式和稳定机制；研究压差、流动剪切等外部载荷及其变化模式对界面失稳过程的影响以及界面的失效模式，建立界面失稳的判定方法；在此基础上，建立界面体系动态行为的数理模型，并对仿生功能界面系统的承载能力进行预测和验证，进而构筑面向微流控器件的仿生密封，并阐明其工作原理；同时，研究仿生密封对微流动的影响，分析气/液、液/液功能界面作用下器件的介质阻力、传热和传质特性，提出仿生密封的综合设计方法。最终，通过项目研究，揭示仿生仿生微结构作用下气/液、液/液界面的演变机理，建立仿生密封的设计理论，为解决微流控器件动态密封等问题提供有效的理论和技术。

本课题以槐叶萍、跳虫等动植物为原型，提出了基于仿生表面微结构与流体界面效应的微尺度“动态”密封技术。首先，以槐叶萍和跳虫为仿生原型，分别分析和提取出其调控流体界面的生物特征结构，并通过软光刻和表面修饰方法制备出仿生微结构，从而成功开发了用于微通道的仿生密封微结构；同时，构建了微流仿生密封的多尺度耦合仿真模型。在此基础上，设计了仿生密封承载机理和影响因素分析测试平台，并通过试验研究了在恒定工况条件下仿生微结构的特性对气/液、液/液界面影响；揭示了仿生微结构作用下的界面承载机理，给出了预测仿生界面系统行为的方法。第二，研究了微通道内的流动压差、流动剪切等不同载荷作用下，气/液、液/液界面的失稳条件和失效模式，探明了影响气/液和液/液界面稳定性的主要因素及其作用规律；测试了流体种类、输入方式和仿生界面系统亲疏水性能差异对仿生密封系统承载能力和失效机制的影响，提出了仿生界面系统稳态条件和失稳判据。第三，建立了面向微流控器件的仿生密封设计和制备方法，研究了仿生密封的工作特性，分析仿生密封对微通道内流场、密封界面质能传输行为等因素的影响，并进一步探明其影响机制，提出了微流控器件仿生密封结构的设计准则，并建立了仿生密封的综合性能设计和调控方法。基于该方法，分别面向“人工肺”、“快速止血”和“抗凝织构”等应用需求设计了仿生密封结构，并完成了原理验证。本研究开发了面向微尺度流动的仿生密封结构，揭示了仿生微结构作用下气/液、液/液界面的演变机理，建立仿生密封的设计理论，为解决微流控器件“动态”密封问题提供了理论和技术支持，有效拓展了微流控芯片在高效质能交换场景的应用。