基于几何反弹簧结构的高分辨率MEMS加速度计

High-resolution MEMS Accelerometer Based on Geometric Anti-spring Structure

为了提高MEMS加速度计分辨率和灵敏度,提出并设计了一种基于几何反弹簧原理的新型MEMS加速度计结构。拟采用静电力将加速度计静态工作点设置在梁低刚度位置来提高灵敏度。首先通过理论计算和有限元仿真,分析了几何反弹簧结构实现准零刚度的原理,并优化了关键几何参数;其次基于免划片SOI工艺完成了MEMS芯片制作;最后搭建了开环测试电路进行测试验证。测试结果表明:施加25 V偏置电压后,加速度计灵敏度从46.3 mV/g提高至51.1 mV/g,线性度为0.99%。验证了静电偏置几何反弹簧结构通过降低刚度系数来提高加速度计的灵敏度的可行性。

A new MEMS accelerometer based on geometric anti-spring principle was presented and designed to improve the resolution and sensitivity.The static working point of the accelerometer was set at the position of low stiffness of the beam by electrical force to improve sensitivity.Firstly,the principle of realizing quasi-zero stiffness of geometric anti-spring principle was analyzed and the key geometric parameters were optimized through theoretical calculation and finite element simulation.Secondly,MEMS chips were fabricated based on a dicing free SOI process.Finally,an open loop test circuit was built for testing and verification.The test results show that the sensitivity of accelerometer increased from 46.3 mV/gto 51.1 mV/g with a linearity of 0.99%[KG*9]after applied a 25 V bias voltage.This verified the feasibility of improving the sensitivity of accelerometer through reducing the stiffness coefficient of the electrostatic bias geometric anti-spring structure.