Long period fiber grating-based biosensing: Recent trends and future perspectives

Decades have passed since the first demonstration of a long-period fiber grating (LPFG) and its practical application for sensors, and, in this period, manufacturing techniques, sensitivity enhancement strategies and measurement methodologies have undergone a huge development. Despite the high level of knowledge and the very high number of publications, a step forward in the creation of an integrated tool based on LPFGs and with a high level of Technology Readiness Level has yet to be achieved. The driving force of the present review is to evidence those recent manuscripts that in some way could open up new lines of research in this field with the aim of approaching this breakthrough. An introductory part is also dedicated to the description of the basic concepts and conventional sensitivity enhancement strategies. A final discussion on possible future trends is reported in the concluding section.