Modeling and Analysis of Temperature-Compensated Fiber Bragg Grating Sensor Based on Flexure Hinge Beam and Diaphragm for Low-Pressure Detection

Pressure determination is an essential measure for safety assessment in modern applications. Conventional methods for measuring pressure have been replaced by fiber Bragg grating (FBG) sensors owing to inherent benefits. However, enhancing pressure sensitivity at the low-pressure range (< 10 kPa) is still a challenge for FBG sensors. Low pressure fails to induce significant strain on FBG, reducing the sensor's sensitivity. Therefore, a sensitizing mechanism must be incorporated into the sensor design along with a proper selection of materials. This paper presents mathematical modeling and simulation analysis of an FBG pressure sensor that uses a circular diaphragm and a flexure hinge-based beam made of acrylonitrile butadiene styrene as a sensing mechanism unit. A cascaded FBG is fixed on the notch surface of the flexure hinge beam which provides the measuring signal is based on Bragg wavelength. The sensor also eliminates the effect of temperature cross-sensitivity using cascade FBG. This mechanical configuration amplifies the low pressure to strain on the FBG. This design has the advantage of high sensitivity, compact size and high linearity. Here, the analysis of circular diaphragm and circular flexure hinge-based beam structure through finite element analysis and theoretical calculation has been carried out. Comparative analysis with the stainless steel sensor indicates the sensitivity of 80 pm/kPa for the ABS sensor which is 16 times greater than that of the stainless steel sensor. Such a sensor can be widely used for low-pressure measurements such as gas and oil pipelines, aircraft wall pressure, and heating, ventilation and air-conditioning.