Optimization Design And Implementation Of MEMS Vector Hydrophone

MEMS bionic vector hydrophone plays an important role in underwater detection due to its features,including,vector property,low cost,rigid installation and so on.However,there are still some problems in practical application,such as left-right ambiguity of vector hydrophone in underwater positioning and significant reduction of sensitivity of hydrophone after packaging.In this paper,based on the existing research results of MEMS bionic vector hydrophone,the sound pressure-particle vibration velocity composite MEMS vector hydrophone,which can improve the sensitivity and positioning ability of MEMS hydrophone under the premise of ensuring a certain working bandwidth,is designed and tested for the sake of solving above problems.Firstly,the bionic principle,hydroacoustic vibration pickup principle and sensing principle of cilium microstructure are briefly introduced in this paper.Then,the mechanical model of MEMS cilium microstructure is optimized,and the final expression formula is obtained by establishing a two-degree of freedom mechanical model to theoretically analyze the stress on the cross-beam and the natural frequency of the microstructure.Next,a numerical interval of the structural parameters is obtained,which can improve the sensitivity and working bandwidth simultaneously.Through comparing the results of mechanical model analysis,fluid-solid interaction analysis and experimental verification,it can be concluded that this numerical interval can effectively solve the current problem of the contradictive relationship between sensitivity and working bandwidth of MEMS vector hydrophone.Secondly,the structure optimized is designed.In order to improve the sensitivity of hydrophone under the condition of ensuring a certain working bandwidth,two microstructure models of vector hydrophone is proposed.And the finite element simulation software is used to carry out parameters optimization function,statics analysis,modal analysis and fluid-structure interaction analysis as well as the final structure dimension is obtained.Thirdly,the shell packaging of hydrophone is designed.To solve the problem of decreased sensitivity of hydrophone after packaging,the packaging method of loose blue nitrile butadiene sound-transparent cap is selected and acoustic simulation is carried out.To solve the problem of left-right ambiguity of previous vector hydrophone in positioning,sound pressure-vibration velocity composite hydrophone shell,which has two structures(discrete structure and integrated structure),is designed.The packaging fabrication of composite MEMS hydrophone is finally completed.Finally,based on the above optimized content,the test of composite MEMS bionic vector hydrophone,which includes sensitivity test,directivity test and pressure-resisting test,is completed by the method of comparison calibration.In addition,the sensitivity and directivity curves of the composite MEMS bionic vector hydrophone are obtained as well as the feasibility of the composite shell is proved.