A fiber bragg grating pressure sensor with temperature compensation based on diaphragm-cantilever structure

Pressure sensors are essential devices for pressure measurement and safety evaluation in modern industrial production and engineering application. According to the FBG sensing technology, this paper presents and studies a FBG pressure sensor that uses a diaphragm and a cantilever as a sensing unit. Two FBGs of this sensor are bonded on the top and bottom surfaces of the cantilever, respectively, and the center wavelength shift difference between the two FBGs is used as a measuring signal, thus improving the pressure measuring sensitivity and avoiding any effect of temperature cross-sensitivity. The measuring principle of this sensor is introduced, and the diaphragm structure of the sensor is analyzed through theoretical calculation and finite element analysis. Experimental results indicate that this sensor has a sensitivity of 339.956 pm/MPa and a linear fitting coefficient of 99.997% in the pressure range from 0 to 10 MPa, and the maximum pressure measuring error caused in the temperature range from 5 to 70 °C is 0.93%, so the temperature compensation effects are remarkable. Such a FBG pressure sensor can be extensively used for quasi-distributed long-term online monitoring of the static or dynamic pressure of liquid or gas in industrial production.