Novel Capacitive Sensing System Design of a Microelectromechanical Systems Accelerometer for Gravity Measurement Applications

Zhu. Li ¹, Wen Jie Wu ¹, Pan Pan Zheng ¹, Jin Quan Liu ¹, Ji Fan ^1,2 and Liang Cheng Tu ^1,2,*

¹   MOE Key Laboratory of Fundamental Physical Quantities Measurement, School of Physic, Huazhong University of Science and Technology, Wuhan 430074, China;

²   Institute of Geophysics, Huazhong University of Science and Technology, Wuhan 430074, China

*   Correspondence: tlc@hust.edu.cn; Tel.: +86-27-8755-8394

Academic Editors: Frank Niklaus and Roy Knechtel

Received: 15 June 2016; Accepted: 26 August 2016; Published: date

Abstract: This paper presents an in-plane sandwich nano-g microelectromechanical systems (MEMS) accelerometer. The proof-mass fabrication is based on silicon etching through technology using inductive coupled plasma (ICP) etching. The capacitive detection system, which employs the area-changing sensing method, combines elementary capacitive pickup electrodes with periodic-sensing-array transducers. In order to achieve a large dynamic range with an ultrahigh resolution, the capacitive detection system employs two periodic-sensing-array transducers. Each of them can provide numbers for the signal period in the entire operating range. The suspended proof-mass is encapsulated between two glass caps, which results in a three dimensional structure. The measured resonant frequency and quality factor (Q) are 13.2 Hz and 47, respectively. The calibration response of a ±0.7 g input acceleration is presented, and the accelerometer system presents a sensitivity of 122 V/g and a noise floor of 30 ng/√Hz (at 1 Hz, and 1 atm). The bias stability for a period of 10 h is 30 μg. The device has endured a shock up to ±2.6 g, and the full scale output appears to be approximately ±1.4 g presently. This work presents a new opportunity for highly sensitive MEMS fabrication to enable future high-precision measurement applications, such as for gravity measurements.

Keywords: MEMS; three dimensional (3D); capacitive sensing system design; large dynamic range; high resolution; high-precision measurement

http://www.mdpi.com/2072-666X/7/9/167