基于湿敏介质内部微波电磁微扰的湿度检测研究

Utilizing the microwave devices for humidity sensing can meet the requirements, such as low power consumption and simple wireless communication, of the IoT sensor terminals. However, Microwave-based humidity sensors generally suffer from low sensitivity, linearity, as well as high error rates, etc. This project researches against the mechanism of near-field electromagnetic field perturbation of the microwave humidity sensor, through combining the sweep frequency tests among the ultra-wide band range and analyzing the derivative parameters for precise modeling, which instructs the sensor design and film parameter modification therefore achieves the comprehensive promotion of microwave humidity detection performances. The main works includes: (1) Explore the mutually targeted optimization between the microwave resonators and humidity-sensing film to enhance the electromagnetic intensity, quality factor, and filling factor inside the sensitive area; (2) Analyze the multi-derived parameters under the ultra-wideband frequency sweep tests, and improve the humidity-sensing properties through optimizing these parameters and operation frequency ranges; (3) Summarize the cooperative working mechanism between the resonators and humidity-sensitive films, then establish the equivalent circuit and physical model, and finally develop a microwave humidity sensor with excellent performances. As a basic research for application, this project focuses on the study of operation mechanism, device modeling, operation frequency band and parameter analysis of the microwave humidity sensor, so as to improve the sensor performance and provide crucial references for the system construction and mechanism research of other microwave detection schemes.

采用微波器件作为湿度检测模块可满足物联网系统对传感器终端低功耗和易于对外通讯等关键需求，然而当前该类型传感器在灵敏度、线性度、误差率等多项性能指标上仍存在缺陷。本项目针对微波湿度传感器的近场电磁微扰机理展开研究，结合超宽频扫频与多衍生参数分析进行精确建模，指导传感器设计与薄膜参数调整，实现湿度检测性能的综合提升。主要工作包括：(1)探索微波谐振器与湿敏薄膜相互针对性的优化改进方案，实现敏感区域内电磁强度、品质因数和填充因数的提升；(2)研究多衍生参数在超宽频扫频下的湿度检测特征，优化衍生参数与频带选用方案以提升感湿特性；(3)探讨微波谐振器与湿敏薄膜的协同工作机理，建立等效电路和物理模型，研制一款性能优越的微波湿度传感器。本项目作为应用基础研究，通过对微波湿度传感器工作机理、器件建模、工作频带与参数分析进行研究，实现传感器性能综合提升，为其他微波类检测方案的系统构建与机理研究提供重要参考。

微波检测作为一种传统的检测手段，因其非接触和可穿透的独特优势被用于测距、测损、测距等领域。本研究对微波检测技术在新领域的应用和关键技术进行了探索，包括微波湿度传感、微波生物传感等。首先对微波检测电极进行了优化设计，提出了针对检测谐振点的构建调控方案，并对基于耦合、辐射等不同类型的敏感结构设计与工作机制进行了探索。提出了一种基于有源变容二极管方案的调频传感结构，研究了微波工作频率对检测速度、灵敏度的影响。研究了复合湿敏材料，包括高分子、金属、陶瓷等，在进行湿度检测时与微波信号的协同作用。此外，将微波检测研究进一步拓展至生物检测领域，通过构建微波阵列实现了在无适配体下的不同类型物质的区分与浓度检测，并研究了微流控技术对检测效果加强的意义。最后，面向微波检测应用，提出了一套基于PLL的微波检测电路架构，对工作模型、噪声模型等进行了充分探讨。