静电负刚度微机电加速度计的两种检测模式分析

Analysis of two detection modes of electrostatic negative stiffness MEMS accelerometer

为了探索能大幅提高灵敏度的全新检测模式,针对频率检测和模态局部化检测两种检测模式的静电负刚度微机电加速度计,进行了原理分析和仿真比较。通过分析两种检测模式下加速度计的敏感、检测原理,推导出其振动方程和检测信号的理想模型。研究发现系统的耦合系数和静电力是影响灵敏度与线性度的关键因素,并对此进行了有限元仿真与分析。仿真分析结果表明基于模态局部化检测的加速度计灵敏度为4.8/g,相对灵敏度为3800000 ppm,与传统频率检测方式相比相对灵敏度提高了三个数量级。同时耦合系数与模态局部化检测的加速度计相对灵敏度呈负相关增长趋势;静电力与两者相对灵敏度呈正相关趋势。针对两种检测方式的比较和影响两种检测模式性能因素的研究,对未来提高加速度计性能和结构设计提供一定的理论支持。

In order to explore a new detection mode which can greatly improve the sensitivity,the principle analysis and simulation comparison of electrostatic negative stiffness MEMS accelerometer with two detection modes,frequency detection and mode-localization detection were conducted.By analyzing the sensitivity and detection principle of the accelerometer in two detection modes,the ideal models of the vibration equation and detection signal are derived.It is found that the coupling coefficient and the electrostatic force are the key factors affecting the sensitivity and linearity of the system,and the finite element simulation and analysis are carried out.The results show that the sensitivity of the accelerometer based on mode-localization detection is 4.8/g and the relative sensitivity is 3800000 ppm,which is three orders of magnitude higher than the traditional frequency detection mode.At the same time,the coupling coefficient is negatively correlated with the relative sensitivity of mode-localization detection,while the electrostatic force is positively correlated with the relative sensitivity of two detection modes.The comparison of the two detection methods and the researching on the factors affecting the performance of the two detection modes provide certain theoretical support for improving the performance and structural design of the accelerometer in the future.