高灵敏度是微质量传感器准确探测细菌、病毒和气体等物质的关键指标。虽然借助微型化的高阶模态梁振动可以有效提升探测灵敏度, 但微尺度效应也降低了传感器的抗环境干扰能力。因此, 如何在特定尺度约束下提升高阶模态传感器的灵敏度已成为谐振式微传感器设计的前沿问题。本文在研究弹性梁几何构型、压电层尺寸与有效质量分布对振动模态影响关系的基础上, 建立了压电驱动多阶梯梁式微质量传感器的灵敏度分析模型, 以传感器灵敏度提升最大为目标, 建立了高阶振动模态下悬臂梁几何构型优化设计模型, 得到了在不同振动模态下具有最高灵敏度的悬臂梁构型, 使同尺寸传感器的灵敏度提升了10.0~15.0倍。考虑驱动位置与制造成本约束, 设计并研制了具有六阶梯梁结构的高阶模态微质量传感器。实验结果表明, 总长度为17.6 mm的六阶梯梁微质量传感器的灵敏度为18.8×104 Hz/g, 考虑制造误差的影响, 其二阶模态灵敏度为同尺寸等截面梁传感器的10.0倍, 较一阶模态同尺寸传感器灵敏度提升了19.8倍, 从而验证了所提出的高阶模态微质量传感器灵敏度提升方法的有效性和可行性。

High sensitivity serves as the key indicator for micro-mass sensor to accurately detect substances such as bacteria, virus and gases etc. In spite of the fact that the detection sensitivity can be improved by vibration of miniaturized high order mode micro-cantilever, the micro-size effect, at the same time, lowers anti-jamming capability of the sensor. Hence, how to improve the sensitivity of high-order mode sensor under special size constraint has been leading edge problem for sensor design. In this paper, based on the impacts of cantilever configuration, piezoelectric layer size and effective mass distribution on the vibration mode, a sensitivity analysis mode for piezoelectric driving multi-stepped micro-mass sensor was established; and, with sensor sensitivity improvement as the goal, a optimization design model for cantilever configuration in high-order mode was created, thus obtaining a cantilever structure with the highest sensitivity in different vibration modes, which helped achieve a sensitivity improvement of 10.0~15.0 times in sensor of different sizes. Considering the constraint of driving position and manufacturing cost, a high-order mode micro-mass sensor with six-step cantilever structure was designed and developed. The results show that sensitivity of the micro-mass sensor with six-step cantilever structure (overall length: 17.6 mm) is 18.8×104 Hz/g. Taking the impact of manufacturing error into consideration, its sensitivity under second-order mode is 10.0 times higher than that of the sensor with cantilever structure of the same size and cross section, with an improvement of 19.8 times compared with sensor of the same size under first-order mode. In this way, effectiveness and feasibility of the method for sensitivity improvement of high-order mode micro-mass sensor are verified.