Micro bending beam based optical fiber grating sensors for physical and chemical measurands

We propse the application of sensors based on the intrinsic bend sensitivity of Bragg gratings inscribed in D-shaped fibers. The first example is a viscosity sensor, consisting of the D-shaped fiber with a sphere attached to the tip of the fiber. The force exerted on the sphere by the laminar flow of a fluid with unknown viscosity bends the fiber, and with this shifts the Bragg wavelength of the inscribed Bragg grating. The other one is a hydrogen senosr, which uses the influence of hydrogen on a palladium foil attached to the Bragg grating. The palladium foil, which is frictionally connected to the flat surface of the D-shaped fiber, is stretched under the influence of hydrogen and with this stretches/bends the fiber.