As the sensitivity of a piezoelectric mass sensor directly depends on the structural frequency variation induced by the mass added. This paper proposes a structure designing method for improving the measuring sensitivity of the mass sensor by using a structure which consists of a symmetrical trough (Ⅰ-shaped cross-section) cantilever and piezoelectric films. Then, we design and fabricate a novel piezoelectric resonance micro-mass sensor. Considering the influences of the section shape, natural frequency and the vibration mode on the sensitivity, an analytical model is established for analyzing the frequency variation caused by the micro particles. With the same geometric parameters, the simulation and experiments are performed for the sensors with the I-shaped cross-section cantilever and the rectangular section cantilever. It shows that the first order natural frequency of the Ⅰ-shape cross-section cantilever is 1 851 Hz, and that of the rectangular section cantilever is 1 610 Hz. Moreover, corresponding sensor sensitivities are 3. 12 × 104 and 1. 5× 104 Hz/g, respectively, and the former is twice of the latter. The method is feasible and effective for improving the measuring precision of mass sensors.%压电式微质量传感器的测试精度直接依赖于结构频率对质量变化的灵敏程度.本文利用对称槽型梁和压电薄膜组成的对称敏感结构,提出了一种提高传感器灵敏度的结构设计方法,并设计了一种高精度谐振式微质量传感器.建立了结构频率变化对吸附质量敏感性的分析模型,并研究了槽型截面参数、自振频率及振动模态对灵敏度的影响.与矩形截面结构进行了仿真与实验对比,结果表明,相同几何尺寸参数下,槽型截面悬臂梁的一阶自振频率为1 851 Hz,矩形截面悬臂梁的一阶自振频率为1 610 Hz,相应的传感器灵敏度则分别为3.12×104 Hz/g和1.5×104 Hz/g,前者是后者的2倍.该项设计为提高微质量传感器灵敏度提供了一种新思路.
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