Advancements and challenges in photonic crystal fibre- based sensors for biomedical applications

Photonic Crystal Fibres (PCFs) have emerged as an essential innovation in current sensor technology due to its outstanding capacity to regulate light and enhance light-matter interaction, resulting in highly sensitive and customisable detection for a wide range of biomedical applications. This paper provides a clear understanding of the fundamentals underlying photonic crystals (PhC) and PCF structures, including their augmentation via surface plasmon resonance (SPR) and the important design parameters influencing sensitivity, confinement, and fabrication feasibility. It also discusses current advances in chemical, physical, refractive index (RI), bacterial, environmental, gas, and biological sensing, backed up with case studies that show the adaptability of PCF-based sensors. Special emphasis is placed on biomedical applications, where PCFs have helped to develop high-resolution imaging, label-free biomarker detection, and precise monitoring of cancer, glucose levels, and other blood parameters. Despite these advancements, significant difficulties remain to the widespread deployment of PCF sensors, including fabrication difficulty, long-term stability issues, biocompatibility concerns, and commercialisation barriers. Looking ahead, the assessment highlights intriguing opportunities in hybrid photonic-plasmonic designs, microfluidic integration, improved materials, and the use of artificial intelligence for data analysis. Overall, the insights given demonstrate the considerable potential of PCF-based sensors to evolve into dependable, scalable tools that can significantly advance future biomedical diagnostic technologies.