MEMS加速度计作为MEMS应用领域中最早开始研究的传感器之一,是一种微型的机电设备,它可以感知物体在多个轴上的加速度分量。如今,基于微电子机械的加速度计已被广泛应用于太空测量、惯性导航、消费电子、汽车电子和地质勘探等各个领域,其重量往往只有几毫克重,足迹肉眼不可见。本文综述了MEMS加速度计的发展历史,重点介绍了早期油阻尼压阻式微加速度计和空气阻尼电容式微加速度计的结构和原理,并分析了近年MEMS加速度计的发展趋势与应用。
As one of the earliest sensors in the field of MEMS application, MEMS accelerometer is a micro electromechanical device, which can sense the acceleration components of objects on multiple axes. Today, accelerometers based on microelectronics and machinery have been widely used in space measurement, inertial navigation, consumer electronics, automotive electronics, geological exploration and other fields. Their weight is often only a few milligrams and their footprints are invisible to the naked eye. This paper summarizes the development history of MEMS accelerome-ters, focuses on the structure and principle of early oil damping piezoresistive micro accelerometers and air damping capacitive micro accelerometers, and analyzes the development trend and application of MEMS accelerometers in recent years.
Research on the Development and Application of MEMS Accelerometer
Zhen Zhen, Hong Zhu
School of Mechano-Electronic Engineering, Xidian University, Xi’an Shaanxi
Received: Jan. 29th, 2022; accepted: Mar. 7th, 2022; published: Mar. 14th, 2022
ABSTRACT
As one of the earliest sensors in the field of MEMS application, MEMS accelerometer is a micro electromechanical device, which can sense the acceleration components of objects on multiple axes. Today, accelerometers based on microelectronics and machinery have been widely used in space measurement, inertial navigation, consumer electronics, automotive electronics, geological exploration and other fields. Their weight is often only a few milligrams and their footprints are invisible to the naked eye. This paper summarizes the development history of MEMS accelerometers, focuses on the structure and principle of early oil damping piezoresistive micro accelerometers and air damping capacitive micro accelerometers, and analyzes the development trend and application of MEMS accelerometers in recent years.
由于传统的单臂梁结构的加速度传感器横向效应较大,不同机构开始展开采用不同的结构来减小加速度传感器的横向灵敏度。2000年,美国的Aaron Partridge等人设计了一种横向侧壁敏感的压阻式加速度计,通过斜向离子注入技术在梁侧边注入淡硼压阻该传感器的灵敏度有3 mV/g,固有频率为700 Hz [11]。2013年我国的张永平教授及其团队设计了一款三轴压阻式加速度传感器,该传感器采用四边四固支梁结构,在每根梁的根部都用三组惠斯顿电桥测量X,Y,Z三轴加速度,图3为该加速度计的基本原理示意图,其中 R 1 ~ R 4 组成了X轴的惠斯顿电桥, R 5 ~ R 8 组成了Y轴的惠斯顿电桥, R 9 ~ R 16 组成了Z轴的惠斯顿电桥,三组惠斯顿电桥构成三个电阻器分别测量X,Y,Z三轴加速度,故而每组桥只需负责自己方向的加速度分量,每个桥只需对自己的给定方向敏感,大大减小了加速度计的横向效应,,这种结构的加速度计将各轴横向灵敏度之间的影响控制在5%以下 [12]。
其中 C 0 表示初始电容大小, Δ d 则为可移动极板移动的距离。综上可以得到加速度和电容之间的变化关系为:
a = d 0 w 0 2 2 C 0 Δ C (17)
当 Δ d 远小于 d 0 时,w远小于 w 0 ,MEMS微加速度计可以实现从 Δ a 到 Δ C 的转变,且加速度大小与差分电容变化量近似为线性关系,经后续电路转换测量后达到检测加速度的效果。
图5中描述了一个早期具有空气阻尼器功能的电容型硅加速度计 [16],该加速度计采用玻璃–硅–玻璃三明治式结构,作为惯性质量和电容器极板的活动板由一个或二个悬臂梁所支承,当加速度信号输入时,就会导致感应器内的检测电容出现变化,而利用接口电路检测电容的改变就可以得到输入速率的大小。当时该加速度计的模拟输出信号为5 V/g,横向灵敏度低于0.4%,整体组件的大小为33 mm × 15 mm × 5 mm。
图5. 电容式微传感器结构 [16]
由于传统加速度计结构及检测电路中寄生电容的影响,加速度计的稳定性无法得到保证,1988年Huang S. M等人研制了一种精确时序的电荷充放电电路,该电路利用时序对电荷充放电达到精准控制,大大减小了寄生电容的影响,提高了整个加速度计系统的抗干扰能力 [17]。2007年党丽辉等人发现加速度计自身的结构会影响分辨率、线性度、稳定性、灵敏度等性能指标,并得出了梳齿式MMA具有灵敏度高、稳定性好、结构简单等优点的结论 [18]。2020年,牛昊彬等人针对小型化加速度计的需求设计了了一款全硅梳齿电容式MEMS加速度计,加速度计采用“日”字型的结构方案,检测模块和施力模块电容采用变间隙梳齿构成,测试结果表明,该加速度计的稳定性优于100 μg,灵敏度约为80 mV/g,稳定性良好,且该加速度记得封装尺寸只有4 mm × 4 mm × 0.85 mm,尺寸非常小 [19]。后来,随着国防科技等的迅速发展,单轴微加速度计已经不能满足各行业的需求,双轴和三轴微加速度计的研究也慢慢展开步伐,2005年,Chae等人提出了一种三轴微加速度计,该加速度计由三个单独的单轴加速度计组成其测量的电容灵敏度达到了2.9 pF/g [20]。由于Z轴加速度计结构独特的面外运动方式,在参与MEMS加速度计的单片三轴集成化时,需要对Z轴进行单独设计。2018年,Mohammed等人提出了一种采用扭摆式结构的高动态范围的混合梁Z轴电容式加速度计,该加速度计利用扭转梁两侧质量不平衡的特点,使得Z轴在感性加速度变化时,让质量块与顶部固定极点间形成差动电容变化,可以有效提高加速度计的动态范围,实现更好的检测灵敏度,其电容灵敏度达到了12 fF/g [21]。
甄 真,朱 红. MEMS加速度计的发展和应用的研究Research on the Development and Application of MEMS Accelerometer[J]. 仪器与设备, 2022, 10(01): 1-10. https://doi.org/10.12677/IaE.2022.101001
参考文献ReferencesRoylance, L.M. and Angell, J.B. (1979) A Batch-Fabricated Silicon Accelerometer. IEEE Transactions on Electron Devices, 26, 1911-1917. <br>https://doi.org/10.1109/T-ED.1979.19795Kuehnel, W. and Sherman, S. (1994) A Surface Micromachined Silicon Accelerometer with On-Chip Detection Circuitry. Sensors & Actuators A, 45, 7-16. <br>https://doi.org/10.1016/0924-4247(94)00815-9Monajemi, P. and Ayazi, F. (2006) Design Optimiza-tion and Implementation of a Microgravity Capacitive HARPSS Accelerometer. IEEE Sensors Journal, 6, 39-46. <br>https://doi.org/10.1109/JSEN.2005.854134Qu, H., Fang, D. and Xie, H. (2008) A Monolithic CMOS-MEMS 3-Axis Accelerometer with a Low-Noise, Low-Power Dual-Chopper Amplifier. IEEE Sensor Journal, 8, 1511-1518.
<br>https://doi.org/10.1109/JSEN.2008.923582Krishnamoorthy, U., Iii, R., Bogart, G.R., et al. (2008) In-Plane MEMS-Based Nano-g Accelerometer with Sub-Wavelength Optical Resonant Sensor. Sensors & Actuators A: Physical, 145-146, 283-290.
<br>https://doi.org/10.1016/j.sna.2008.03.017Seok, S., Kim, H. and Chun, K. (2004) An Inertial-Grade Laterally-Driven MEMS Differential Resonant Accelerometer. Proceedings of IEEE Sensors, 2, 654-657.白凤蕊. 新型一体式石英振梁加速度计研究[D]: [硕士学位论文]. 南京: 东南大学, 2016.Lima, V., Cabral, J., Kuhlmann, B., et al. (2020) Small-Size MEMS Accelerometer Encapsulated in Vacuum Using Sigma-Delta Modulation. 2020 IEEE International Symposium on Inertial Sensors and Systems (INERTIAL), Piscataway, 23-26 March 2020, 1-4. <br>https://doi.org/10.1109/INERTIAL48129.2020.9090096Gattere, G., Rizzini, F. and Dall’Oglio, C. (2020) Antistiction Recoil Accelerometer. 2020 IEEE International Symposium on Inertial Sensors and Systems (INERTIAL), Piscataway, 23-26 March 2020, 1-4.
<br>https://doi.org/10.1109/INERTIAL48129.2020.9090055Mutoh, M., Iyoda, M., Fujita, K., et al. (1990) Development of Integrated Semiconductor-Type Acceleration. IEEE Workshop on Electronic Applications in Transportation, Dearborn, 18-19 October 1990, 35-38.Partridge, A., Reynolds, J.K., Chui, B.W., et al. (2000) A High-Performance Planar Piezoresistive Accelerometer. Journal of Microelectromechanical Systems, 9, 58-66. <br>https://doi.org/10.1109/84.825778Zhang, Y.P., He, C.D., Yu, J.Q., et al. (2013) An Integrated MEMS Piezoresistive Tri-Axis Accelerometer. Journal of Semiconductors, 34, Article ID: 104009. <br>https://doi.org/10.1088/1674-4926/34/10/104009Roy, A.L., Sarkar, H. and Dutta, A. (2014) A 11igh Precision S01 MEMS-CMOS+49 Piezoresistive Accelerometer. Sensors and Actuators A: Physical, 210, 77-85. <br>https://doi.org/10.1016/j.sna.2014.01.036Liu, F., Gao, S., Niu, S., et al. (2018) Optimal Design of High-g MEMS Piezoresistive Accelerometer Based on Timoshenko Beam Theory. Microsystem Technologies, 24, 855-858. <br>https://doi.org/10.1007/s00542-017-3585-4Jia, C., Mao, Q., Luo, G., et al. (2020) Novel High-Performance Piezoresistive Shock Accelerometer for Ultra-High-g Measurement Utilizing Self-Support Sensing Beams. Review of Scientific Instruments, 91, Article ID: 085001.
<br>https://doi.org/10.1063/5.0008451Rudolf, F., Jornod, A., Bergqvist, J., et al. (1990) Precision Accel-erometers with μg Resolution. Sensors & Actuators A Physical, 21, 297-302. <br>https://doi.org/10.1016/0924-4247(90)85059-DHuang, S.M., Stott, A.L., Green, R.G., et al. (1988) Electronic Transducers for Industrial Measurement of Low Value Capacitances. Journal of Physics E Scientific In-struments, 21, 242. <br>https://doi.org/10.1088/0022-3735/21/3/001党丽辉, 胡雪梅. 电容式加速度计的表头结构设计与分析[J]. 昆明冶金高等专科学校学报, 2007, 23(5): 29-32.牛昊彬, 孙国良, 王帅民, 等. 圆片级封装全硅梳齿电容式MEMS加速度计设计[J]. 中国惯性技术学报, 2020(5): 672-676.Chae, J., Kulah, H. and Najafi, K. (2005) A Monolithic Three-Axis Micro-g Micromachined Silicon Capacitive Accelerometer. Journal of Microelectromechanical Systems, 14, 235-242.
<br>https://doi.org/10.1109/JMEMS.2004.839347Mohammed, Z., Elfadel, I.M. and Rasras, M. (2018) High Dynamic Range Z-Axis Hybrid Spring MEMS Capacitive Accelerometer. 20th Symposium on Design, Test, In-tegration and Packaging of MEMS and MOEMS, DTIP, Roma, 22-25 May 2018, 1-4. <br>https://doi.org/10.1109/DTIP.2018.8394219薛连莉, 翟峻仪, 葛悦涛. 2020年国外惯性技术发展与回顾[J]. 导航定位于授时, 2021, 8(3): 59-67.卞玉民, 胡英杰, 李博, 等. MEMS惯性传感器现状与发展趋势[J]. 计测技术, 2019, 39(4): 50-56.王庆敏, 苏木标, 刘玉红, 等. MEMS加速度传感器在桥梁横向动位移监测中的应用[C]. 2007’中国仪器仪表与测控技术交流大会论文集(二). 2007: 352-355.鲁鹏威, 贾方秀, 郄剑文. 基于MEMS的帕金森病人体姿态分类监测系统[J]. 现代电子技术, 2017(16): 169-172+177.岳鹏, 史震, 王剑, 等. 基于MEMS加速度计的无陀螺惯导系统[J]. 中国惯性技术学报, 2011(2): 30-34.沈玉芃, 杨文钰, 朱鹤, 等. 2020年国外惯性技术的发展与展望[J]. 飞航导弹, 2021(4): 6.