Fiber Bragg grating evanescent wave sensors for chemical and biological applications

While Fiber Bragg Grating (FBG) sensors continue to act as valuable sensing platforms specially when physical parameters have to be measured in single or multipoint configuration, great efforts have been focused in the last decade to convey the great advantages of FBG technology towards the development of new devices and components employable in modern chemical and biological applications. Since the first attempt carried out in 1996 by Meltz et al., many sensing schemes have been proposed based on the evanescent wave effect arising from the surrounding refractive index sensitization of the final device by tailoring either the grating structure or the host fiber. In this chapter, we review the main advances in the area of FBG evanescent wave sensors, with particular emphasis on principles of operation, technological developments, overall performances and discussing in details perspectives and challenges that lie ahead.