柔性基底上悬挂支撑硬质薄膜的屈曲和后屈曲行为

Stretchability is an important property of flexible and stretchable electrons. Buckling of stiff thin films is the theoretical basis for the stretchability of flexible and stretchable electrons. At present, the commonly used method to realize the flexibility and stretchability of inorganic electrons is the interconnected island bridge structure, and the discrete thin film devices are connected through the interconnecting wires. The dispersion of thin films and the introduction of interconnecting lead to conflicts between stretchability and effective area of functional devices, and the stress between the soft substrate and the thin film also affects the electrical properties and the stability of the functional device. This project will propose a new approach to achieving inorganic electronics flexibility and stretchability. A theoretical and experimental study will be made on the buckling and post-buckling behavior of the stiff thin film suspended on a soft substrate with surface relief structure. The mechanical mechanism and influence factors of the buckling / post-buckling deformation of this structure will be revealed. Then the mechanical model of buckling / post-buckling of the stiff thin film suspended on the soft substrate will be established. And the quantitative relationship between the stretchability of the structure and the structural parameters is finally obtained. During tension / relaxation, the interface stress / strain between stiff film and soft substrate approaches zero, so this kind of structure is of great significance to the preparation of flexible and stretchable electronics and is expected to become a new flexible strategy for flexible and stretchable electronics. The research results of this project will provide the corresponding theoretical guidance for the application of stiff thin film / soft substrate system in flexible and stretchable electronics.

可延展性是柔性电子的重要特性，薄膜的屈曲是实现柔性电子可延展性的理论依据。目前实现无机电子柔性和可延展性的常用方法为互联岛桥结构，通过互连导线连接离散化的薄膜器件，而薄膜的离散以及互连导线的引入,导致延展性和功能器件的有效覆盖面积之间存在矛盾，同时柔性基底与薄膜间的应力也会影响功能器件的电性能及稳定性。本项目提出了一种实现无机电子柔性化和可延展性的新方法。针对悬挂支撑在柔性基底上硬质薄膜的屈曲和后屈曲行为进行理论和实验研究，揭示该结构屈曲/后屈曲变形的力学机理及影响因素，建立描述悬挂支撑硬质薄膜屈曲/后屈曲行为的力学模型，最终得到描述该结构延展性与结构参数的定量关系。在拉伸/松弛过程中，硬质薄膜和柔性基底之间界面应力/应变接近为零，因此该种结构对柔性电子的制备具有重要意义，有望成为柔性电子的新型柔性化策略。本项目研究结果将为薄膜/柔性基底系统在柔性电子中的应用提供相应的理论指导。

本项目开展了微结构的形状特性对电子薄膜悬挂在柔性基底上的屈曲理论研究，建立了微结构几何参数、排列间距与电子薄膜屈曲形貌(如屈曲幅值、波长)之间的关系，揭示了含三角架和梯形架表面微结构柔性基底上悬挂支撑硬质薄膜的可控屈曲和后屈曲行为机理。分析了带金字塔表面微结构基底上悬挂支撑薄膜的双向屈曲和后屈曲行为，建立了悬挂支撑薄膜的双向屈曲和后屈曲行为力学模型，得到了描述双向屈曲薄膜的屈曲幅值和最大应变与两个方向的预应变之间的定量关系。基于柔性基底的薄膜屈曲结构，设计了一种可穿戴、双向可延展微带天线，可以承受较大的拉伸、弯曲和扭转等机械变形。提出了一种新型的悬挂支撑薄膜—柱状基底系统，针对该系统分析了带微结构柱状柔性基底上悬挂硬质薄膜的周向屈曲和后屈曲行为，基于能量法建立了悬挂支撑薄膜的周向屈曲和后屈曲行为的力学理论模型，能够描述柱状薄膜的周向屈曲和后屈曲行为。所提出的这种结构在柔性医疗领域有着较好的应用前景。提出了一种新型的正n棱柱柔性基底-薄膜系统，在棱柱的多个棱柱面上同时设置微结构从而实现多个无机薄膜电子器件的同时屈曲，通过这种方法可以显著提高电子器件的面积覆盖率，有效避免整个薄膜屈曲时形成的褶皱，避免薄膜中的应变过大，同时可以保持较高的电子器件面积覆盖率。提出了一种用于监测膀胱实时活动和治疗膀胱活动不足症的可膨胀、植入式复合光、电子医疗器件，通过体外实验和有限元仿真分析了膀胱组织膨胀/收缩过程中网状结构的几何变形、应变分布和网状结构与膀胱组织接触界面间的接触压力，得到了应变参量与膀胱体积之间的关系曲线。该器件为在临床上治疗人类膀胱活动不足症提供了可能。