Recent Advances in Sensor Applications of Microstructured Optical Fibers: A Review

The collection and interpretation of environmental data in a reliable and secure manner is of undeniable importance for the enhancement of healthcare quality and the mitigation of ecological risks associated with human activities. In pursuit of this objective, optical fibers have been utilized for several decades as a means of providing more flexible, compact, and cost-effective sensing platforms. Furthermore, the advent of technologies, such as the laser, improved fabrication processes, and 3-D printing, has made it possible to engrave microstructures into optical fiber cores, resulting in a significant enhancement in sensitivity without compromising portability and compactness. The development of microstructured optical fibers (MOFs) has transformed the domain of optical sensing, as their distinctive capacity to confine and manipulate light surpasses that of conventional fibers. Their diverse structural configurations, encompassing fiber Bragg gratings (FBGs), photonic crystal fibers (PCFs), and tapered fibers, offer enhanced sensitivity and adaptability, rendering them invaluable in diverse applications. This review offers a comprehensive overview of recent advances in MOF technologies, emphasizing significant innovations in fiber design and fabrication and their influence on sensor performance over the past year. It is intended to serve as a comprehensive introductory resource for researchers and engineers, delineating the latest trends, technological advantages, and future directions in the rapidly evolving field of MOF-based sensors. Moreover, particular emphasis is placed on specific MOF types, including hollow-core and anti-resonant fibers (ARFs), which have demonstrated considerable potential in environmental monitoring, biomedical sensing, and industrial applications. Additionally, this review encompasses the advancement of emerging structures, such as D-shaped and multicore fibers, which continue to challenge the limits of fiber-based sensors.