MEMS based Geophones and Seismometers

Abstract The recent development of Micro-Electro-Mechanical System (MEMS) technology has provided new methods for researchers to design and fabricate seismometers and geophones in small scale which will enable seismic sensors achieve higher sensitivity with a larger frequency band when compared with traditional instruments. In this paper, we review the development of various types of MEMS based geophones and seismometers by dividing them into two types according to the state of inertial mass (liquid or solid type). Within all types of seismic sensors, emphasis has been put on the highly sensitive electrochemical sensors and the frequently used capacitive seismic sensors. The working principles, detailed fabrication processes, as well as the advantages or limitations are also summarized. Moreover, the levelling system assembled with the seismic sensors is also included in this review. They are added to help seismometers work properly when tilted. Since MEMS fabrication technology with small mass also brings magnified intrinsic noise to the seismic sensors, self-noise issues and some possible modifications on structures or signal processing circuits to reduce this noise are discussed.