Papers by Author: Guang Bei Li

Abstract: A closed-loop control system designed for a SOI-MEMS resonant accelerometer is proposed in this paper. The sensor chip was developed by silicon-direct-bonding SOI wafer (10+2+290 um) with MEMS fabrication technology. Z-axis acceleration is differentially detected by using two H-style vibrating beams through a frequency shift caused by the inertial force acting as bending stress loading. The electromagnetically excitation and detection is adopted to make the closed-loop control of the sensor easier. The whole closed-loop control system designed for the accelerometer mainly consists of amplifier, automatic gain control (AGC) circuit, buffer and phase shifter. Testing results show that the accelerometer with the closed-loop system can work stable at the frequency of 58.958 kHz when 1g z-axis acceleration is applied which is consistent with the open-loop testing.

Abstract: Petroleum prospecting and early warning of some geological disaster increasingly depend on the accelerometers which can detect vibrate of frequency below 1Hz, but it’s embarrassing that accelerometers based on Si or SiO2 structure make an awful performance in this frequency range. Electrochemical accelerometers were developed in 1990s. With fluidics to be inertial mass, electrochemical accelerometer not only show an excellent property in low frequency, but also has a wide dynamic range. However, traditional fabrication process of electrochemical accelerometer is rather complex and can’t eliminate the noise due to the inconsistency and asymmetry of electrodes. To solve these problems, a scheme based on MEMS is proposed here, including design, fabrication and package. Properties of electrochemical accelerometer (EAM) are tested in two conditions at last.

Abstract: An electrochemical seismic sensor (ECSS), which consists of interdigital electrodes immersed in electrolyte solution, based on MEMS technology is studied theoretically and experimentally in the paper. The output current of the sensor is employed to measure the ground motion. The device has a small size, simple design and fabrication process with low cost. Preliminary test results show that the novel electrochemical seismic sensor has satisfactory characteristics.