信号增强型薄膜体声波重金属离子传感器研究

In recent years, it is very important to real-time detect the heavy metal ions with high sensitivity. In order to enhance the detection signal, this project seeks to design a new film bulk acoustic resonator and nanocomposite sensitive film. The main research contents are as follows: (1) Study the effect of different orientations of the ZnO piezoelectric films on the acoustic wave mode. Try to improve the electromechanical coupling coefficient of the shear wave mode in order to reduce the sensor's damping in the liquid environment. (2) Design Bragg reflector to limit the acoustic energy between the electrodes and the piezoelectric film, which is used to enhance the sensor response signal. (3) Design thioglycolic acid modified tellurium Cadmium nanospheres as the sensitive film. The quality of electrode surface is amplified by a three-layer structure of nano-composite. The amplified signal was tested and verified. (4) Project applicants have extensive experience in sensor development. If we can successfully build a high-sensitivity sensor for rapid detection of heavy metal ions, it will lay a theoretical and technical foundation for effectively alleviating heavy metal pollution and developing new environmental monitoring sensors.

近年来各类重金属污染事件频发，实现对其高灵敏度实时检测十分重要。为了增强水环境中重金属离子传感器的检测信号，本项目力求设计新的薄膜体声波传感器，并以此为基础结合纳米复合物敏感膜制作新型重金属离子传感器。具体研究内容如下：（1）研究ZnO压电薄膜的不同晶粒取向对体声波模式的影响，增强剪切波模式机电耦合系数，减小传感器在液态环境中的工作阻尼；（2）设计布拉格反射栅，将声波能量最大化地限制在由上下电极及压电薄膜组成的压电振荡堆中，增强传感器响应信号；（3）设计基于巯基乙酸修饰的碲化镉纳米球作为敏感膜，与重金属离子形成汉堡包结构，放大电极表面的质量变化，该放大信号被实验测试和验证；（4）构建快速检测重金属离子的高灵敏度传感器，为有效缓解重金属污染和研制出新型环境监测传感器奠定理论和技术基础。

为了增强水环境中重金属离子传感器的检测信号，本项目设计剪切波模式薄膜体声波传感器，结合纳米复合敏感膜制作重金属离子传感器。具体研究内容如下：（1）建立了FBAR剪切波模式理论模型，分析了不同c轴ZnO倾斜角下声波的声速和有效机电耦合系数，发现在43°时ZnO压电薄膜只激发剪切波模式体声波。（2）建立了接触液体FBAR的Mason模型，c轴取向FBAR的Q值在空气中为846.89，而在水中为1.627，下降了两个数量级。在c轴倾斜角为43°，即剪切波模式FBAR时Q值最大，损耗最小。当剪切波接触液体时，谐振频率与液体的粘度和密度呈现特有的函数关系，与Kanazawa-Gordon理论一致。（3）采用磁控溅射制备了ZnO压电薄膜，并用XRD和SEM进行表征，发现通过调整倾斜目标方向角可使ZnO薄膜做到c轴倾斜角为13.1°。（4）设计并制作了FBAR，并用矢量网络分析仪进行测试分析FBAR的S参数和史密斯圆图。（5）制备了重金属离子敏感膜并在体声波器件上进行测试，通过TGA修饰的CdTe纳米球，用于信号的放大，增加器件的检测灵敏度。修饰后的体声波谐振对铅离子、镉离子和铜离子三种重金属离子的检测极限分别为0.096，0.089和0.189 μg/L。