Yang Bo, Gao Xiaoyong, Li Cheng
School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China.
Key Laboratory of Micro-Inertial Instrument and Advanced Navigation Technology, Ministry of Education, Nanjing 210096, China.
Micromachines (Basel). 2020 Apr 17;11(4):422. doi: 10.3390/mi11040422.
A novel micromachined z-axis torsional accelerometer based on the tunneling magnetoresistive effect is presented in this paper. The plane main structure bonded with permanent magnetic film is driven to twist under the action of inertial acceleration, which results in the opposite variation of the magnetic field intensity. The variation of the magnetic field is measured by two differential tunneling magnetoresistive sensors arranged on the top substrate respectively. Electrostatic feedback electrodes plated on the bottom substrate are used to revert the plane main structure to an equilibrium state and realize the closed-loop detection of acceleration. A modal simulation of the micromachined z-axis tunneling magnetoresistive accelerometer was implemented to verify the theoretical formula and the structural optimization. Simultaneously, the characteristics of the magnetic field were analyzed to optimize the layout of the tunneling magnetoresistance accelerometer by finite element simulation. The plane main structure, fabricated with the process of standard deep dry silicon on glass (DDSOG), had dimensions of 8000 μm (length) × 8000 μm (width) × 120μm (height). A prototype of the micromachined z-axis tunneling magnetoresistive accelerometer was produced by micro-assembly of the plane main structure with the tunneling magnetoresistive sensors. The experiment results demonstrate that the prototype has a maximal sensitivity of 1.7 mV/g and an acceleration resolution of 128 μg/Hz along the z-axis sensitive direction.
本文提出了一种基于隧穿磁阻效应的新型微机械z轴扭转加速度计。与永磁膜结合的平面主体结构在惯性加速度作用下被驱动扭转，导致磁场强度产生相反变化。磁场变化由分别布置在顶部基板上的两个差分隧穿磁阻传感器测量。镀在底部基板上的静电反馈电极用于使平面主体结构恢复到平衡状态，并实现加速度的闭环检测。对微机械z轴隧穿磁阻加速度计进行了模态仿真，以验证理论公式并进行结构优化。同时，通过有限元仿真分析磁场特性，以优化隧穿磁阻加速度计的布局。采用标准玻璃上深干法刻蚀硅（DDSOG）工艺制造的平面主体结构，尺寸为8000μm（长）×8000μm（宽）×120μm（高）。通过将平面主体结构与隧穿磁阻传感器进行微组装，制作了微机械z轴隧穿磁阻加速度计的原型。实验结果表明，该原型在z轴敏感方向上的最大灵敏度为1.7mV/g，加速度分辨率为128μg/Hz。
