压电式MEMS仿生结构矢量水声传感机理及其器件基础研究

The vector hydrophone with high sensitiveness and micro-miniature is very important to the development of sonar system. The application prospects and urgent demand of the vector hydrophone is extensive. On the basis of two-dimensional piezoresistive MEMS vector hydrophone, a new passive piezoelectric MEMS bionic vector hydrophone to detect acoustic sensing underwater is proposed, which can achieve high sensitive detection, identification and orientation for ultra-low frequency and long-distance weak signal acoustic target underwater. The research reveals the measuring pressure theory and MEMS bionic vector hydrophone sensing mechanism with four cantilever beams-mass based on the serial sensitive units of piezoelectric functional thin films. The integration manufacture method of piezoelectric MEMS bionic vector hydrophone with high dynamic detection range, low power consumption and noise, miniaturization is investigated. And the reliable method for extracting three-dimensional acoustic signal of piezoelectric MEMS bionic vector hydrophone is studied. The mathematical relationship and orientation theory of vector hydrophones on the x, y, z three-dimensional direction of underwater acoustic target is established. The technical problem of single vector hydrophone without simultaneously achieving three-dimensional orientation is solved. The project provides theory guidance and key technical support for piezoelectric MEMS bionic vector hydrophone development and application.

高灵敏微型矢量水听器应用前景广泛且需求迫切，是现代声呐系统前沿技术的重要发展方向。本项目在前期二维指向性压阻式MEMS矢量水听器研究基础上，提出一种压电式仿生MEMS无源器件基础结构的水声传感探测新方法，为实现超低频、远距离弱信号水下声目标的高灵敏探测、识别与定向提供一种新思路。系统研究揭示基于串联压电功能薄膜敏感单元的四悬臂梁－质量块纤毛仿生MEMS结构的声压信号拾取与矢量水声传感机理；实现具有高动态探测范围、低功耗和噪声低、微小型化优势的压电式MEMS仿生结构矢量水听器一体化集成制造，研究压电式MEMS仿生矢量水听器无源器件三维空间感知信号的可靠提取方法，建立矢量水听器对水声目标在x、y、z方向三维空间的指向数学关系和定向理论，解决现有单个矢量水听器不能同时实现三维空间定向的技术难题，为新型压电式MEMS仿生矢量水听器的开发应用提供基础理论指导和关键技术支持。

为解决面向水下低频、远程、多目标物体识别技术难题，结合仿生原理，本项目设计了基于压电效应的MEMS仿生结构矢量水声传感器。基于仿生学原理和压电效应提高矢量水声传感器灵敏度；并通过MEMS技术实现该无源器件的微小型化。本研究所设计传感器具有体积小、动态测试范围广、噪声低、灵敏度高等优点。通过对水声传感器的理论分析，论证本项目制作的器件的可行性。根据上述理论，设计了四悬臂梁-中心连接体结构，建立了数学模型，对其固有频率，灵敏度，应力以及刚度进行分析，并通过MATLAB、ANSYS进行仿真、分析、对比。在MEMS加工技术平台上完成器件基础芯片的制作，组装。模仿水生动物感觉器，完成仿生封装，制造出压电式MEMS仿生矢量水声传感器的模型样机。最后，自主搭建振动测试平台初步完成模型样机的灵敏度、指向性的校准实验。实验结果表明设计的水听器质量轻、体积小、具有“8”字指向性。灵敏度为-192.2dB@500Hz（0dB参考值 1V/ μPa），频带宽度为20~300Hz。100Hz时频带内指向性凹点深度大于20dB，轴向灵敏度最大值不对称性小于0.2dB；300Hz时频带内指向性凹点深度大于23.5dB，轴向灵敏度最大值不对称性小于0.8dB。