梯形变截面悬臂梁式质量传感器设计与分析

Design and analysis of high resolution mass sensor incorporating grooved trapezoidal cantilever

谐振式微质量传感器的灵敏度取决于弹性元件的几何尺寸和结构形式。单纯依靠结构尺寸微型化方法已难以满足传感器工程实用性的要求,因而需要探索新的改善传感器性能的方法。在保证传感器外形尺寸不变的基础上,提出通过改变弹性梁的表面形状(梯形)和截面构型(槽型)来进一步提升传感器灵敏度的新方法,建立了基于槽型变截面弹性梁的传感器灵敏度分析模型,分析了影响传感器灵敏度的关键设计因素,得到了结构设计参数、自振频率及灵敏度之间的关系表达式。仿真结果表明,在相同外形尺寸参数下,矩形截面悬臂梁传感器的自振频率和质量检测灵敏度为1 254.2 Hz和9.8×103Hz/g,槽型变截面悬臂梁传感器的自振频率和灵敏度为1 776.1 Hz和38.0×103Hz/g。相对于矩形截面梁传感器,灵敏度提高了287.8%,从而验证了提出的灵敏度提升方法的有效性和可行性。

The sensitivity of resonant cantilever sensor depends on the cantilever geometric dimensions and structure con- figuration. The micromation method only depending on structure dimension change can hardly fulfill the requirement of sensor engineering practicability,and a new method for improving the sensor performance is needed. Different from tradi- tional dimension reducing method for improving the mass detection sensitivity with M/NEMS technology,on the basis of keeping the external dimension of the sensor unchanged through changing , in this paper, a new sensitivity improving method is proposed both the surface shape and cross-section of the cantilever,and a novel piezoelectric resonant mass sensor is proposed by employing gyooved trapezoidal cantilever as the key elastic element. The sensitivity analytical model of the sensor based on the grooved beam with varied cross-section is established. The key design factors influencing sensor sensi- tivity is analyzed ,and the relationship expression between the structure design parameters and the natural frequency as well as sensitivity of the sensor is obtained. The numerical simulation and experimental results show that the natural frequency and sensitivity of the grooved varying cross-section cantilever sensor is 1 776.1 Hz and 38.0 ×10^3 Hz/g,respectively ;and the natural frequency and sensitivity of the rectangular cross-section cantilever sensor is 1 254.2 Hz and 9.8 × 10^3 Hz/g, respectively. The sensitivity of the grooved varying cross-section cantilever sensor is nearly 287.8% better than that of the rectangular cross-section sensor under the same geometric dimension parameter condition. Finally ,the good consistency be- tween the numerical simulation and experimental results verifies the feasibility of the proposed sensitivity improving method.