表皮微流控芯片的防塌顶结构优化及液样收集可控设计

As a new member of microfluidics, epifluidics (EFs) is one of the future trends in wearable devices. Optimal design of EFs is indispensable for wearable microfluidic devices. An optimal design of epifluidic structures is critical to the high reliability and performance of wearable microfluidic devices. Unfortunately, the existing design strategies for stability of the EF structures are empirical, and the investigation on sample collection is rarely reported. How to optimize EF structures and develop some new sampling technologies in a convenient and effective way, has been a major concern of academia. In this project, we will employ continuum mechanical theory and microfluidic mechanical models (capillary imbibition inverse calculation, surface thermodynamic analysis etc.) as well as finite element analysis to investigate the mechanism of the instability of epifluidic structure and propose a roof collapse analytic criterion, further evaluate the column-support mechanism and obtain the sampling parameters in EFs. Moreover, we will reduce adhesion of the microfluidic wall to prevent the collapse of EFs by constructing the hierarchical and special wettable surface, and explore a facile and controllable sampling approaches in EFs based on a local capillary-driven effect. The results will establish the relationship among the technical parameters and required function - deformation energy, work of adhesion and critical bursting pressure - stability and sampling of EFs. Our project will provide an essential theoretical and experimental perspective to forecast the epifluidics for future high-performance and comfortable wearable devices.

表皮微流控作为一种新兴的微流控技术，已成为可穿戴设备领域的前沿。开发高可靠性、多功能可穿戴微流控设备离不开表皮微流控芯片(EFs)的优化设计，即要求其具有稳定力学结构和高效集样功能。目前，人们仅依靠经验方法来解决EFs中常见塌陷等失稳问题，其可控集样研究则刚刚起步。如何优化稳定EFs结构、发展新型集样技术已成为学术界新问题。本项目拟在理论上采用连续介质力学和微流控相关理论(毛细吸入反问题等)，并佐以有限元模拟来揭示微腔体结构变形规律、提出塌顶分析判据、设置合理增强方案、获取集样参数等。同时，拟从实验上构筑特殊润湿性腔壁使其塌陷后可恢复，利用屈曲引导褶皱、局域毛细驱动效应等实现目标样在封闭腔体中无阀控制和无泵驱动。旨在建立前期工艺/后期功能需求—变形能、黏附功及突破压力阈值等—结构稳定性/定时定量集样等关系，为EFs实用化提供理论和实验依据，为设计新一代面向健康医疗的可穿戴设备提供新思路。

表皮微流控作为一种新兴的微流控技术，已成为可穿戴设备领域的研究前沿。开发高可靠性、多功能可穿戴微流控设备离不开其结构的优化设计，即要求具有稳定力学结构和高效集样功能。本项目采用能量法结合板壳理论分析了表皮微流控芯片的自塌顶失稳问题，提出了包括液体过充、支柱增强、特殊浸润腔壁构筑等在内的结构稳定策略。结合凸优化理论，进一步分析了芯片中任意形状腔体的结构稳定性，获得了一个无量纲参数—标准黏附功(包括了腔体相关的材料和几何参数)，经实验验证后提出了普适的稳定性判据。为了实现芯片的高效集样功能，本项目还发展了时间次序集样、脱水提醒等非电学皮肤贴合类器件。结合微流体力学理论(毛细流动力学、表面热力学等)优化器件结构，得到了可行的微流控芯片布局(单疏水阀结合单开口腔室、十字阀触发双层腔等)。此外，基于表面特殊浸润性调控，本项目还实现了器件表面与液体相互作用或内部各类液体流动行为的操控，开发了水合环境中使用的皮肤可贴合应变传感器。这些工作为表皮微流控芯片的个性化健康医疗应用提供了重要的理论基础及实验依据。