Study On The Over-load Protection And Compensation Of The Temperature Draft Of The High Accuracy MEMS Silicon Differential Pressure Sensor

Silicon micro pressure sensor is one of the major study fields of micro electro mechanical system. And it is wildly applied in all kinds of areas, especially in vehicle industry, aerospace, industry control, environment monitor and measure, biomedical and so on.The character of over- load protection of pressure sensor is a key performance index. The sickness component of the structure of the pressure sensor is the silicon membrane which is usually designed as the sensitive unit, and the silicon membrane will be of plastic deformation or even break down if the loaded pressure is far bigger than the span of the measure pressure. It can be found that the traditional pressure sensor can’t fit the requirement of the character of over-load protection in the rigorous application environment just like the petrochemical industry and aerospace.In order to enhance the capacity of over- load protection, a new structure of sensor is designed which contains three diaphragms. And the crinkle diaphragm will contact the shaped body to protect the whole sensor in case of the over- load. The advantages of the method are simple, low cost, reliable, easy to serialization and so on. Additionally, the compensation of temperature draft error is one of the difficulties of high accuracy pressure sensor, and it is studied in this paper.The paper study on the character of over-load protection of pressure sensor and the principle of the over- load protection of the three diaphragms structure is advanced. Basing on the research of the deformation character of the circle diaphragm which including the pre-stress, the structural sizes of the differential sensor are designed and optimized. The deformation of diaphragm is simulated by the ANSYS software; the trial of the maximal deflection the diaphragm is done; the calculation method of how to obtain the theoretical over- load pressure is described. And the test results of the actual over- load pressure in case of the indoor temperature confirm the validity of the design of sensor.Additionally, basing on the analysis of the component of the temperature draft error, a new algorithm of the compensation of temperature draft error is proposed which including the least square method and the BP neutral network method. And the main process of the algorithm is to derive the function of the compensation coefficient which is referring to the measured pressure and the environment temperature, so that the output signal ca n be modified by the micro chip.