谐振式微加速度计静电刚度应用分析及实验

Application Analysis and Experiment of Electrostatic Stiffness of Resonant Micro Accelerometer

静电负刚度能够调谐微机械振梁的谐振频率,但静电负刚度过大会带来谐振梁的稳定性和可靠性问题。文中介绍了静电负刚度效应在谐振加速度计中的应用,并在刚度和质量比约束条件下,推导出输出谐振频率与加载直流检测电压的非线性关系,分析传感器灵敏度、量程与直流检测电压的非线性耦合关系。流片微结构并封装开环测试表明,不同的直流检测电压对应谐振频率存在非线性静电负刚度效应,在加速度为-1g、0g、1g 3种条件下,谐振频率非线性减小,灵敏度和量程关于检测电压交叉耦合,大的检测电压和加速度会导致微机构不稳定和失效。

The electrostatic negative stiffness can tune the resonant frequency of the micromachined vibration beam,but too large electrostatic negative stiffness can affect the stability and reliability of the vibration beam.The application of electrostatic negative stiffness effect in resonant accelerometer was introduced.Under the constraint of stiffness and mass ratio,the nonlinear relationship between output resonant frequency and loaded DC detection voltage was deduced.The nonlinear coupling relationship between sensor sensitivity,range and DC detection voltage was analyzed.The results of open-loop test show that different DC detection voltages have nonlinear electrostatic negative stiffness effect on resonant frequency.Under the conditions of-1g,0g and 1g,the resonant frequency decreases nonlinearly,and the sensitivity and range are cross coupled with the detection voltage.Large detection voltage and acceleration will lead to instability and failure of the micro mechanism.