Advanced Optical Sensing Techniques for Biomolecular Detection in the Human Body: Principles, Technologies, and...

Optical biosensing technologies have become viable platforms for biomolecular detection, providing rapid and sensitive analysis of a wide range of biological targets such as proteins, nucleic acids, and metabolites. The principles, technological advances, and clinical potential of key optical sensing modalities such as surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS), fluorescence, and interferometric sensors are critically reviewed. Although these methods have made important breakthroughs in label-free detection, real-time monitoring, and dimension reduction, many are limited by the requirement of controlled laboratory environments, complicated instrumentation, and high fabrication costs. The more recent discoveries in nanophotonics, 2D materials, and integration on a microscale have improved signal stability and device portability, which help to narrow the divide between the real-world implementation of point-of-care (PoC) diagnostics. Automated data interpretation and constant healthcare monitoring are further supported by the inclusion of artificial intelligence (AI) and the Internet of Medical Things (IoMT). Instead of an alleged technological revolution, the current review concentrates on the gradual advances in optical biosensing in the path of clinically valid, affordable, and non-invasive biomolecular diagnostics.