Research On MEMS Piezoresistive Pressure Sensor With Static Pressure Head And Constant Temperature Control

In recent years,the demand for MEMS piezoresistive pressure sensors has increased,and their performance requirements have become higher and higher.Conventional piezoresistive pressure sensors on the market generally do not have both high sensitivity and high linearity,and are susceptible to environmental temperature and wind speed.Exactly based on this kind of situation,this study focuses on designing a higher performance MEMS piezoresistive pressure sensor measurement system with static pressure head and constant temperature control.Firstly,a MEMS pressure sensor with L-shaped structure is designed.The sensor introduces a convex varistors and four L-shaped peninsula structures by partially etching the SOI silicon film,which takes into account high sensitivity and low nonlinearity error.The sensitivity of the pressure sensor was simulated and analyzed by ANSYS finite element software,and the sensor structure and material property parameters were determined.According to the results of simulation optimization,the MEMS process flow was designed and the processing and packaging of the pressure sensor chip was completed.Secondly,the static head model is constructed.The influence of wind speed and altitude on the static pressure effect is simulated by CFD simulation software FLUENT.The optimal structure of the static pressure head is determined according to the CFD simulation results.The static pressure head was fabricated by 3D printing technology and the wind speed test was completed.The experimental results were compared with the simulation results and the output data without static pressure head.The results show that the designed static presssure head device has a good static pressure effect.Then,a hardware measurement system is designed for the processed pressure sensor chip.The system uses S5PV210 microprocessor as the core component to realize the functions of signal acquisition and data management,PID constant temperature control,etc.The least square algorithm is used to compensate the nonlinear error and hysteresis error of the data collected by the pressure sensor.The real-time display and transmission of data isaccomplished through a graphical interface written in QT.Finally,the experiment tests are carried out on the constant temperature control system and the packaged MEMS piezoresistive pressure sensor.The experimental results reveal that the temperature error of the constant temperature control system designed in this research is less than ±0.5°C in the temperature range of-40°C to 50°C,which can effectively weaken the temperature drift phenomenon.At room temperature,the sensitivity of the MEMS silicon piezoresistive pressure sensor is 0.056 mV/(V·kPa)and the nonlinear error is 1.12% in the range of 0kPa~105kPa.The overall error of the pressure sensor after compensation by the least squares method is less than 0.24%FS.In the temperature range of-40°C~50°C,the sensitivity of the pressure sensor under constant temperature control is0.059mV/(V·kPa),the nonlinear error is 1.05%,and the overall error after algorithm compensation is 0.16%FS when the full scale is 120 kPa.The above results proves that the static pressure head and constant temperature control system designed in this work have certain reference significance for improving the measurement accuracy of piezoresistive pressure sensors.