Research On Temperature Characteristics And Compensation Method Of MEMS Vector Hydrophone

With the continuous expansion of the application range of hydroacoustics,underwater information acquisition and transmission technology occupies an increasingly important position.In the face of complex marine environment,whether it is seabed mapping,military anti-submarine communication,or underwater acoustic communication,hydrophones are the most basic and widely used sensors.The MEMS vector hydrophone is designed based on the piezoresistive effect of semiconductor materials,and has the advantages of high sensitivity,wide frequency band,small volume,etc.However,the sensor has a very high sensitivity to temperature,and its output will occur when affected by temperature.temperature drift.In practical engineering applications,MEMS vector hydrophones are often used in working environments with different temperatures,and the sensitivity drift will affect the measurement accuracy.Therefore,it is of great significance to study the temperature characteristics of MEMS vector hydrophones and perform temperature compensation.In this paper,the mechanical model of the MEMS vector hydrophone is firstly established,and the stress-strain analysis and frequency characteristic analysis of its sensitive structure are carried out.Then the influence of temperature on MEMS vector hydrophone is analyzed in principle.Including: the effect of temperature on the resistivity of the varistor in the sensitive structure;the relationship between the piezoresistive coefficient and the doping concentration and temperature;the influence of the packaging stress of the sensor during the preparation process;the relationship between the thermal expansion coefficient and temperature of different materials for preparing the sensor;the relationship between Young’s modulus,sound speed and temperature,etc.Based on the above theoretical analysis,the sensor model was established using COMSOL software,and the current-solid heat transfer multiphysics coupling simulation analysis was carried out.It was concluded that the sensitivity of the MEMS vector hydrophone decreased with the increase of temperature.On the basis of theoretical analysis and simulation,the temperature characteristic test scheme of MEMS vector hydrophone is designed and the test system is built.The sensitivity test experiments of scalar hydrophone and vector hydrophone are carried out in the water environment of 0-40℃.The trend of sensitivity with temperature was verified.After multifrequency test and single-frequency repeated test,the general law that the sensitivity of MEMS vector hydrophone is affected by ambient temperature is obtained: within the experimentally designed temperature range,as the temperature increases,the sensitivity of MEMS vector hydrophone increases.The overall sensitivity shows a decreasing trend,and the variation is within 1.8d B,which is basically consistent with the theoretical and simulation analysis results.Finally,according to the temperature characteristic of the MEMS vector hydrophone sensitivity,a temperature compensation method is designed to improve the measurement accuracy of the sensor.After comparative analysis of hardware compensation and algorithm compensation,it is finally determined to use the least squares method combined with spline interpolation for temperature compensation.Through compensation,it is concluded that in a wide temperature range,the sensitivity of the MEMS vector hydrophone is highly coincident with the sensitivity curve at room temperature,which reduces the influence of temperature drift.The influence of sensor temperature drift on the measurement results lays the foundation for the engineering application of MEMS vector hydrophones.