Study On Optical MEMS Pressure And Temperature Sensors Based On Wavelength Demodulation

Optical fiber MEMS sensor not only has the advantages of small volume, strong function, high sensitivity and easy mass production of MEMS sensor, but also possesses the characteristics of optical sensors of ideal transmission frequency bandwidth, large dynamic measurement range and easy to form distributed measurement network. The design, fabrication and test method of optical fiber Fabry-Perot MEMS pressure sensor are focused on,and a new type of optical fiber MEMS temperature sensor is presented.An optical MEMS micro-pressure sensor is designed. The influence of the diaphragm thickness on the deflection of the pressure sensitive membrane is discussed. On this basis,the fiber optic pressure sensor of the mesa structure is designed,and the mechanical model of the mesa diaphragm is established. The influence of the diaphragm thickness and the height of the mesa on the sensor performance is analyzed. The mechanical properties of mesa diaphragm are simulated by the finite element analysis software ANSYS. The effect of the cavity depth on the sensor performance is discussed.Considering the actual structure of the sensor,the formula of pressure sensitive diaphragm deflection under thermal stress is established. The influence of the thickness and radius of the pressure sensitive diaphragm and the thickness of the glass tube on the deflection have been discussed by using the control variable method.The results of the ANSYS simulation are modified by the Levenberg-Marquardt algorithm. The formula for the pressure sensitive film in the case of the solid structure with the glass ring has been obtained.The fabrication process of the sensor is studied, and the pressure test system is built to carry out the performance test. The method of extracting and processing the experimental data is discussed in detail. The cavity length, according to the spectral data extracted from ENLIGHT , is calculated by the peak demodulation method of bimodal tracing. The test results of linearity and sensitivity performance of the prepared sensor samples have been given.A new optical fiber Fabry-Perot MEMS temperature sensor based on bimetallic effect is designed and fabricated. The mechanical model of the sensor is studied,the sensitivity of the sensor is discussed, the bimetallic material is determined, and the rationality of the model is verified by finite element software ANSYS. The experimental test system is established and the temperature sensor has been tested.Which can provide some reference value for studying the temperature compensation of silicon-based pressure sensor.