Design And Process Research Of MEMS Bionic Vector Underwater Acoustic Sensor

With the development of the acoustic stealth technique, the noise-lever radiated by underwater moving targets becomes lower and lower. This is the new challenge for noise measurement technology, and particularly for the low frequency long-range detection. The application of vector hydrophone endows several advantages for detection of submarines through array technology,and the technology associated with vector hydrophone becomes a very important investigative aspect in underwater acoustic field. Nowadays following topics have been attached importance to researches about design of vector hydrophones:(1) High sensitivity;(2) Ultra-low-frequency detection;(3) Miniaturization of vector hydrophone;(4) Self-noise control.Above problems require development of new sensor technology based on MEMS technology and be finally solved in sonar design with the help of microsystem integrated technology. In this thesis design & production of vector hydrophone by means of theory of piezoresistive effect and MEMS technology had been proposed, it is desirable that the application of piezoresistive effect may improve the low-frequency sensitivity of vector hydrophone as well as its miniaturization.According to the MEMS technology, a new type MEMS bionic underwater acoustic sensor has been presented, which is based on the piezoresistive effect of the superlattice membrane, and the sensor structure has been fabricated with MEMS process. It expect to improve the low-frequency sensitivity with the high sensitivity piezoresistive effect of superlattice membrane, to detect low frequency acoustic signal with the bionic and acoustic principle of cylinder, to miniaturized the sensor with MEMS technology.According to the auditory principle of fish's stereocilium, a novel silicon based micromachined bionic vector underwater acoustic sensor has been presented. The principle of bionics and hydroacoustics about vector underwater acoustic sensor has been discussed. The distribution of stress on the beam has been performed with FEM (Finite Element Method) simulator. The fabrication has been discussed. The vector direction of the sensor has been measured in acoustic research institute and 715 institute. As the result shows, that the sensor has'8 shape'vector direction, and the sensitivity is up to -200dB.Theoretical analysis and experimental results indicate that it is feasible to use this kind of bionic vector underwater acoustic sensor for detecting submarine sound. Applying the hearing bionic principle of stereocilia to the submarine sound detection domain will develop a new direction for the research on high performance underwater acoustic sensor.The innovation of this paper is: a) The design of the sensor structure is present for the first time based on the auditory principle of fish's stereocilium, so the structure is novel, b) the sensitive unit of the sensor is based on the piezoresistive effect of superlattice membrane, so the principle is new, c) The fabrication of the sensor is based on the MEMS technology, so the manufacture is new. So the research work of this paper is innovative, and paving a road for the design of new sensor.