A Novel Micromachined Z-axis Torsional Accelerometer Based on the Tunneling Magnetoresistive Effect

Abstract

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/Hz0.5 along the z-axis sensitive direction.

Acceleration Sensors: Sensing Mechanisms, Emerging Fabrication Strategies, Materials, and Applications

“…In this structure, a minute displacement of the permanent magnetic film due to displacement of inner proof mass can change the magnetic field and be detected by the differential tunneling magnetoresistive sensors. The sensitivity of the device is 1.7 mV/ g ; Figure c shows the structure of the device, and Figure d shows the SEM image of the fabricated device …”

“…Copyright 2019 MDPI. (c) Structure of the device and (d) SEM image of the fabricated device by Yang et al Reproduced with permission from ref . Copyright 2020 MDPI.…”

“…The sensitivity of the device is 1.7 mV/g; Figure 6c shows the structure of the device, and Figure 6d shows the SEM image of the fabricated device. 55 Electrostatic/Electromagnetic Accelerometers. Research on electrostatic and electromagnetic accelerometers is growing day by day due to their minimal heating and low energy loss.…”

Silicon-Based Zipper Photonic Crystal Cavity Optomechanical System for Accelerometers

“…As one of the basic inertial devices, accelerometers are widely used in military and civilian fields such as industrial automation, robotics, aerospace, automobiles, consumer electronics, and earthquake recording. There are already various accelerometers with different working principles, including piezoresistive [1][2][3][4], capacitive [5][6][7], resonant [8][9][10][11], optical [12][13][14], etc. Traditional piezoresistive and capacitive accelerometers use pressure or displacement caused by external acceleration to convert changes in electrical parameters through structural design to achieve acceleration measurements.…”