Label-free Biosensors based on Long Period Fiber Gratings: A Review

Fiber optic label-free biosensors are currently experiencing wide diffusion, as they combine the performance of optical measurements with the advantages of optical fiber. This paper presents a comprehensive review about the design, development and testing of biosensor solutions based on in-fiber long period gratings (LPG). The attention is focused on optical transducers and methodologies allowing a significant enhancement of the sensitivity. Moreover, coating nanomaterials, biofunctionalization strategies and recognition elements providing the selectivity to the target analyte are reported in detail. The aim is to provide a detailed review concerning the state of the art about LPG-based label-free biosensors and to outline the future research trends.