Plasmonic Fiber Bragg Grating Sensor for Health Monitoring Applications: Review on Fiber Structures, Material Properties, and Deposition Techniques

For years, technologies in monitoring diseases and sickness for early stages detection have been actively developed. Previously, fiber Bragg Grating (FBG) has been widely used for strain, pressure and temperature sensing. Recently, this type of fiber optics has broadened its application in health monitoring field including cancer and various types of viruses’ detection. The combination of surface plasmon resonance (SPR) and propagating cladding modes created by FBG has proved able to enhance the strength of evanescent field in which consequentially increase the sensitivity of FBG sensor. This study reviews the utilization of plasmonic fiber Bragg Grating (FBG) in the health monitoring field in recent years by considering the types of FBG, plasmonic materials, metal deposition techniques and their current applications. In health monitoring application, plasmonic tilted FBG (TFBG) displayed impressive sensing ability resulted from the transmitted light coupling into backward cladding combine with the excitation of surface plasmon polaritons compared to the conventional FBG. These applications include cancer diagnosis, glucose detection, protein detection and respiratory problem. Gold with thicknesses between 30 nm and 50 nm is the most preferable noble metal to generate SPR due to its non-oxidized and chemically stable properties compared to other noble metals. Sputtering has become the most extensively used technique for metal film deposition on FBG because of its ability to create excellent film's adhesion and good thickness uniformity compared to dip coating and spin coating. In conclusion, FBG based SPR sensor technology exhibits bright potential for health monitoring applications due to its simple working procedure, high sensitivity and uncomplicated fabrication process.