Abstract

Nanophotonic biosensors have evolved from surface plasmon resonance systems into a broad class of platforms that includes localized plasmonic nanostructures, surface-enhanced Raman spectroscopy, metasurfaces, and metamaterial-enabled biosensors. However, the field continues to be characterized primarily by device-level metrics, such as sensitivity, linewidth, quality factor, and limit of detection, which do not fully capture practical performance in biological environments.

In this work, we argue that nanophotonic biosensing should instead be understood as a system-level process of information transfer. To formalize this perspective, we introduce a four-layer framework based on Mode, Interface, Measurement, and Decision (MIMD). Using this framework, we reinterpret representative advances across major nanophotonic biosensing platforms and show that progress depends not only on stronger optical enhancement, but also on improved coordination across the entire sensing chain.

We further propose that the next stage of the field should be guided by layered sensing architectures that integrate robust linear transduction with nonlinear or inelastic channels to achieve molecular specificity and dynamic characterization.