Modeling of Hydrogel Coated Fiber Bragg Grating pHSensor

This paper present the modeling and simulation ofthe hydrogel coated FBG for pH sensor application. Thehydrogel swelling was modeled by using Poisson-Nernst-Planckequation and mechanical equilibrium equation. The simulationwas done by assuming that the hydrogel was coated on unetchedfiber and etched fiber. The strain induced at the fiber core wasanalyzed using finite element method. It was found that at theregion near the jacketed fiber, the strain is distributednonuniformly. The non uniform area for etched fiber is shorterthan that of unetched fiber. The Bragg wavelength shift due tostrain of the etched fiber is much larger than that of theunetched fiber.