Design and development of pressure sensor based on Fiber Bragg Grating (FBG) for ocean applications

A Fiber Bragg Grating (FBG) based sensors has been designed, fabricated and is being prototyped to measure the ocean water column pressure. To measure the pressure variation, a compact design is made by using stainless steel disks and rubber "O" rings in a closed air cavity setup. The pressure in static freshwater column ranging from 0 to 0.04 MPa was gauged, using closed air cavity setup. Also, another "T" shaped design, for testing, has been made of solid stainless-steel tube with the open-air cavity for an extended range of pressure sensing. By using an oil pressure pump and open-air cavity setup, pressure values from 0 to 0.5 MPa have been measured. In both setups same thickness of copper, stainless steel diaphragms are used to measure the pressure. Range of measurements has been carried out to test both the setups. Results indicate that the pressure sensitivity in closed air cavity setup is 24.95 nm/MPa with linearity 99.72%. In the open-air cavity, setup is 16.22 nm/MPa with linearity 99.34% is achieved. Simulation and experimental studies are performed to validate the efficacy of the designed FBG pressure sensor.