U-Bent Fiber Optic Plasmonic Sensors: Fundamentals, Applications, Challenges, and Future Directions

Plasmonic fiber optic sensors have garnered immense interest in the past two decades owing to their inherent structural, functional, and operational benefits. In particular, U-bent fiber optic sensors with their high evanescent wave absorbance sensitivity offer a unique advantage of efficient monitoring of the optical extinction properties of the plasmonic nanoparticles for the development of a variety of sensing applications. This chapter describes the fundamentals of sensing in the LSPR-based U-bent fiber optic probes. Various factors affecting the performance of plasmonic U-bent probes such as nanoparticle size, shape, geometrical design, and other fiber parameters are discussed in detail. In addition, this chapter provides in-depth coverage of various sensing strategies developed for U-bent plasmonic fiber optic sensor and their applications towards a variety of chemicals and biosensors. Although these plasmonic sensors could achieve the detection limit down to the attomolar levels of the analyte, concerted efforts are needed towards the translation and commercialization of U-bent plasmonic fiber optic sensors to devise a low-cost, field-deployable, point-of-care diagnostic system.