水凝胶中可变形金属纳米网络的双电层电容式声响应特性及其低频水声检测性能研究

The development of flexible pressure sensor in underwater low frequency acoustic detection and acoustic stealth is in urgent need which calls for novel mechanism and new material. In this project, a novel mechanism that deformable metal nano-network electrodes patterned on the surface of hydrogel films can induce the capacitance change of electric double layer (EDL) is first proposed, and the stealth flexible acoustic detector based on this mechanism are designed. Hydrogel, which have perfect match with water environment with negligible acoustic impedance, is used as substrate. Patterned deformable nanonetwork electrode is directly "planted" into the surface layer of hydrogel films.By sensitively responding the deformation of the metal nano-network electrodes under pressure, capacitor change can be induced via changing the EDL area on the nano-network electrodes. Accordingly, flexible acoustic stealth hydrogel-based acoustic detector can be constructed by responding the signal of capacitor change. The response characteristics of the hydrogel devices will be forecasted through the establishment of vibration model of deformable nanonetwork electrode under pressure loading with different frequency, and be optimized via accurately controlling the nano-/micro- multi-scale structures of the deformable nanonetwork electrodes. By further studying the mechanism of the signal transmission and transformation in hydrogel devices, the relationship between acoustic detecting ability and the microstructure and surface pattern of deformable nanonetwork electrodes, as well as physical and chemical properties of hydrogels will be finally revealed. The research will provide novel mechanism, new materials and technology for developing flexible stealth acoustic detector which is suitable for low frequency acoustic detection.

柔性压力传感器在水声低频检测和声学隐身方面的发展急需新机理和新材料的突破。本课题首次提出并阐明“种植”于水凝胶表层的图案化、可变形金属纳米粒子网络电极诱导双电层电容变化新机理，以及基于此原理设计构筑低频水声隐身探测器。以与水环境几乎完美匹配、无声阻抗界面的柔性水凝胶薄膜为基体，研究直接在其表层“种植”图案化金属纳米粒子网络电极的独创技术，通过灵敏地感应外界载荷引起的金属纳米粒子网络电极的变形，改变其形成双电层的面积，诱导电容值的改变，以此作为响应信号设计构筑可探测低频水声的水凝胶双电层电容探测器。建立可变形金属纳米粒子网络电极在不同频率载荷下的振动模型，并通过纳米-微米多尺度结构的精确调控预测、优化水凝胶器件的水声响应特性，阐明其电学信号的传导与转化机制，揭示纳米粒子的形貌和尺寸、图案化结构、水凝胶的性能与水声检测之间的构效关系。为柔性声学隐身低频水声检测提供新机理、新材料

水下声场中低频声信号的探测成为目前海洋声学领域最为关注的问题之一。本课题提出并阐明“种植”于水凝胶表层的图案化、可变形金属纳米粒子网络电极诱导双电层电容变化新机理，以及基于此原理设计构筑低频水声隐身探测器。研究在水凝胶表层“种植”图案化金属纳米粒子网络电极的独创技术，通过灵敏地感应外界载荷引起的金属纳米粒子网络电极的变形，改变其形成双电层（EDL）的面积，诱导电容值的改变，以此作为响应信号设计构筑可探测低频水声的水凝胶双电层电容探测器。分析水凝胶中树枝状银纳米结构的可控制备、对水凝胶物理化学性质影响，构建基于树枝状银纳米结构复合水凝胶的柔性压力传感器及水听器，揭示水凝胶水下声波传感器对声波频率、振幅与方向、频率扫描及响应相位的影响，以及盐离子浓度对声波探测响应灵敏度的影响。与商用水听器相比，该水凝胶水声探测器在小于60赫兹时具有明显更高的信号强度，为低频水声探测奠定了基础。为了克服水凝胶中水分易挥发和电解，导致器件的使用寿命和工作稳定性下降等问题，以不易挥发的具有良好导电性的离子液体代替水为溶剂，设计制备具有金字塔微结构的离子液体凝胶，构建三明治结构压力传感器，并捕捉电极-离子液体凝胶界面EDL的变化监测水下声波。分析了该水听器在直流和交流电工作模式下凝胶的压缩模量对水听器性能的影响、离子液体凝胶水听器对声波的响应、以及对声波频率的响应和工作寿命。与商用水听器相比，该类凝胶水听器对低频声波具有更好的响应信号，最高可相差约60dB，并且对水下声波具有很好的方向辨识性，填补了基于压电陶瓷的声音导航测距（声纳）的性能空白。此外，为了提高柔性器件的寿命和性能稳定性，研发了具有高韧性、快速自恢性能、抗冲击等性能的高强水凝胶，及具有自愈合、自粘附、高拉伸和有宽温度工作区间的纳米复合离子液体凝胶，为水下声波检测器件的发展提供高性能凝胶材料奠定基础。