Abstract: Aiming at the demand of high-precision water pressure measurement in wells, this paper designed a high-sensitivity fiber Bragg grating pressure sensor based on the pressure sensing characteristics of bellows and a cantilever beam-based lever amplification structure. The axial structure of the bellows under pressure is amplified by the lever structure connected by the hinge to the axial strain of the FBG to achieve high-precision measurement of pressure. The mechanical model of the mechanical structure of the sensor is established. The mathematical expression of the wavelength change and pressure of the FBG in the sensor is derived. The pressure sensitivity of the sensor is simulated by the finite element method. The simulated and experimental pressure sensitivities of the sensor are 14.8 pm/kPa and 14.1 pm/kPa, respectively, which are in good agreement. The pressure sensor can accurately measure a certain range of pressure, and by changing the lever arm length parameter, the sensitivity can be changed and the measuring range can be adjusted.

Key words: bellow, fiber Bragg grating, pressure sensor, finite element, simulation