石墨烯薄膜应变传感机理及其面向复杂曲面变形探测的应用研究

Graphene has been widely chosen as the sensitive material for flexible strain sensors, due to its unique two-dimensional (2D) structural characteristics, defect-regulated electronic properties and multi-dimensional spatial adaptability. Nonetheless, graphene synthesized in different routes varies greatly in terms of internal structures. Besides, the electromechanical coupling phenomenon is influenced by many factors, which is complex without a universal theoretical explanation. Therefore, the performance of graphene-based strain sensors is hard to improve. This project aims to explore the signal acquisition and transformation mechanism of macroscopic graphene film as the sensitive materials of strain sensors. In addition, we will design and fabricate flexible strain sensing arrays with high sensitivity, optimal spatial adaptability, low response time and high spatial resolution. In order to explore the strain sensing mechanism, firstly, this project plans to use the self-assembly and structural regulation of graphene to reveal the correspondence between the microscopic and macroscopic topology of graphene and its electromechanical coupling property. Secondly, we will focus on the influence of interface interaction between graphene and elastic substrate, as well as the elastic modulus of substrate, on the sensor performance, and reveal the important role of interface and substrate. The research of these mechanisms benefits the optimization of the strain sensing performance of graphene-based strain sensors, thus eventually provides the theoretical foundation to prepare a graphene film which meets the performance targets of this project. On the other hand, the structural design and fabrication of flexible strain sensing arrays could pave the way for the practical application of graphene-based strain sensors.

石墨烯，具有独特的二维结构、受缺陷调控的电学特性及多维度空间适应性，成为柔性应变传感器强有力的候选敏感材料。然而，不同制备条件获得的石墨烯内部结构差异较大，受多参数影响，其力电耦合现象较为复杂，尚未形成统一的理论解释，限制了传感性能的提升。本项目旨在探究宏观尺度石墨烯薄膜作为应变敏感材料对信号获取与转换的机制，设计并制备具有高灵敏度、优空间适应性、快响应时间、高空间分辨率等优势的柔性阵列应变传感器件。对于机理探究，首先从自组装与结构调控着手，揭示石墨烯多晶结构微观变形、宏观拓扑结构与其力电耦合性能的对应关系；其次着重研究石墨烯与弹性衬底的界面相互作用、衬底弹性模量对传感性能的影响规律，揭示界面及衬底的重要作用。深入探究传感机理，为挖掘和优化传感性能，并筛选出满足项目指标要求的石墨烯结构及其制备工艺提供理论依据。柔性阵列应变传感器件的结构设计与工艺实现也为石墨烯走向实际应用提供实践依据。

近年来，特征尺寸在纳米尺度的二维材料石墨烯被认为是极具应用潜力的、具有超高灵敏度的、适应复杂曲面变形的柔性应变传感器的重要实现方式之一。然而，将纳米尺度的石墨烯组装成宏观尺度的敏感薄膜，需要跨越至少6个数量级，其力电耦合行为受自组装结构及其表界面相互作用的影响，尚未形成统一的理论解释，严重制约了石墨烯应变传感器件的实际应用。本课题通过界面自组装工艺获得宏观尺度的石墨烯薄膜，其微观上呈现片层堆叠紧密排列的特点。创新地把石墨烯片层内部，及其与衬底之间的界面结合强度作为关键参数，研究其对石墨烯断裂及变形模式的影响，阐明片层间滑移-断裂之间的协同关系，从而指导器件性能的调控。本课题主要研究石墨烯毗邻片层及其与衬底之间的界面结合强度调控策略；结合电镜观察和计算仿真，深入研究界面结合对石墨烯层间滑动模式、裂纹的生成模式和对渗流网络演变的影响机制；探索界面结合与传感特性之间的对应关系；开发适应复杂曲面的石墨烯薄膜界面自组装方法；在此基础上制备了柔性应变传感器件及其阵列，实现了高灵敏度、大量程、优空间适应性、快响应时间、高空间分辨率、耐刮擦、低迟滞等能力优势；最终将其应用于可穿戴式人类运动监测中。