中文摘要：

本文推导了双层声波导结构乐甫波传感器的频散方程和质量敏感度。首先，根据连续边界条件求解声波波动方程，并推导双层声波导结构下乐甫波传播的频散方程；然后根据微扰理论推导乐甫波传感器的质量敏感度。文中并最后给出基于ST-90°X石英基片的乐甫波传感器的算例分析。基片表面依次覆盖二氧化硅和金两层声波导，根据上述推导式子计算出乐甫波相速度及质量敏感度随着声波导层厚度变化的特性。结果表明：声波导层厚度增加时，乐甫波相速度减小，乐甫波模式增多，控制波导层厚度可以获得单一的乐甫波模式；选择波导层的厚度，乐甫波传感器可获得最大质量敏感度。

英文摘要：

The paper investigates love wave behavior and mass sensitivity in a double- waveguide Love wave sensor. Firstly, general mechanical displacement and a dispersion equation are derived by solving elastic field equations with continuity boundary condition. Then the mass sensitivity is obtained by combing perturbation theory. An analysis of ST- 90°X/SiO2/Gold structure Love wave sensor is presented. The properties of love wave phase velocity and mass sensitivity are calculated when the thickness of waveguide layers change. The theoretical results show that phase velocity decreases and the number of modes increases as the thickness of the waveguide increases. Furthermore, the sensor can achieve the largest mass sensitivity with a particular waveguide thickness by controlling the thickness of the waveguides.