FBG-Based Liquid Pressure Sensor for Distributed Measurement With a Single Channel in Liquid Environment

In this paper, a novel immersion liquid pressure sensor based on the fiber Bragg grating (FBG)is introduced. Two FBGs are encapsulated in polymer in different forms, according to the deformation principle of the polymer under special constraints which is immersed in liquid, we can get the information of pressure in the liquid. Due to the use of a new packaging method, the proposed sensor can achieve distributed measurement on a single axis, which is difficult for liquid pressure sensor based on FBG to realize and is important for the measurement of pressure in special liquid environments. The sensing principle and mathematical model analysis of the sensor were first introduced and its sensing characteristics were analyzed by numerical simulation and the finite element simulation. The experimental result shows that the sensitivity of two sensors are 51.296 pm/MPa and 46.117 pm/MPa, it is consistent with the theoretical value within the working range of 0~15.5 MPa. The temperature compensation scheme is also considered in the designed sensor. Through the temperature calibration experiment, it is shown that the maximum average difference value is only 4.887 pm at a wide working temperature range 0~44.8° during the measurement.