The Research Of A Piezoelectric Micro-Pressure Sensor For Temperature Compensation

The rapid development of global intelligent process put forward higher requirements to the research and development of a new generation micro sensor system,especially,the research and development of high accuracy high sensitivity micro sensor has become increasingly urgent and important.In recent years,piezoelectric materials have developed rapidly and been used widely,especially in the semiconductor industry.Based on the piezoelectric effect and inverse piezoelectric effect,piezoelectric materials can be used as a sensing element or drive components.Piezoelectric pressure sensor is widely used in the bridge health monitoring,health monitoring,aerospace,cars,ships and etc.However,the instability of polarization intensity of piezoelectric material affected by the temperature have an impact on the accuracy and sensitivity when it as a sensing element.Currently the research of temperature characteristic of piezoelectric sensor as well as temperature compensation method for the piezoelectric sensors is still in the phase of studying.Usually based on the experimental calibration results in advance,using look-up table method to determine the output of piezoelectric pressure sensor in different temperature,this method requires a lot of time,which severely limits the using range of piezoelectric materials.Therefore,this paper proposes a piezoelectric micro-pressure sensor which can realize the temperature compensation,and the temperature characteristic is studied,finally a simple temperature compensation method based on the thermistor is proposed.Firstly,the piezoelectric micro-pressure sensor based on the silicon cup type structure was designed,a fixed circular piezoelectric film as a sensing unit measure the outside pressure,and the temperature compensation method based on the thermistor was proposed.According to the small-deflection theory of thin plates and the piezoelectric equation,the mathematical model of the output of the sensor is established.The influence of film radius and thickness of sensor on its output is analyzed through the software COMSOL Multiphysics to optimize the structure and size of sensor.Through the modal analysis,to determine the sensor working frequency range.Designing sensor testing circuit and test platform,through the experimental to test temperature characteristics of piezoelectric pressure sensor.First,the material parameters of piezoelectric thin film were measured,such as resistance and capacitance,which were analyzed in different temperature.Second,testing sensor structure,analyzing the sensor output in different temperature with elevated pressure.At last,obtaining its performance index according to the experimental results,the sensitivity,accuracy,linearity and the frequency response.According to the experiment results,analyzing the influence of temperature on the sensor performance,temperature compensation method was proposed according to the characteristics that the thermistor resistance changes over temperature.The change of the thermistor resistance was applied to the output of the sensor through the circuit design to achieve the temperature compensation.This compensation method avoided error from the temperature measurement in the process of the look-up table,improved the precision of the sensor.Through experimental to test the output of sensor in elevated temperature with compensation circuit,to validate the feasibility of compensation method.