Quantifying efficacy of the fiber bragg grating sensors in medical applications: a survey

Fiber Bragg grating (FBG) sensors play a decisive role in clinical decisions, where their ability to show chemical inertness, small in size, and high sensitivity makes them superior to the electric sensors for both in situ and ex vivo examinations. In recent years, different FBG sensors have been proposed for medical purposes; yet, ensuring high-resolution, accurate, and highly high-sensitive sensing under complex operating environments remains a challenge. In this paper, the different FBG-based sensors designed for biomechanics sensing, musculoskeletal sensing, non-invasive or minimally invasive surgery, tissue manipulation sensing, tissue thermal ablation sensor, tool shaping sensors, physiological sensing (respiratory sensor, heart rate sensor, blood pressure sensor, temperature sensor), and biosensors are discussed. The existing sensor designs with their respective functionalization, strengths, and limitations are discussed. The depth assessment revealed that the chirped etched FBG, phased grating FBG, TFBG, super-structured FBGs, etc., with optimal grating encapsulation or coating can be vital toward medical sensing and allied clinical decision systems. The study confirms that the use of grating encapsulation or coating can improve sensitivity; however, addressing strain and temperature compensation remains a challenge. Moreover, the use of a peak-tracking method by exploiting refractive index changes can enable accurate biosensing or allied medical sensing tasks.