Plasmonic Sensing Techniques in Optical Biosensors

Plasmonic sensing harnesses collective oscillations of electrons at metal–dielectric interfaces to detect minute changes in the local refractive index induced by molecular binding events. The most established approach, surface plasmon resonance (SPR), typically employs a prism-coupled metal film in a Kretschmann configuration to excite propagating surface plasmons, yielding real-time, label-free analysis of biomolecular interactions. Advances in nanofabrication have given rise to grating-coupled SPR, nanostructured surfaces and metallic nanoparticles that support localized surface plasmon resonances (LSPR). These structures concentrate electromagnetic fields into subwavelength volumes, boosting sensitivity and enabling miniaturisation into lab-on-a-chip formats. Dispersion engineering of plasmonic nanogratings, phase-interrogation schemes and integration with microfluidic platforms have further enhanced resolution, multiplexing and throughput. Applications span from clinical diagnostics and drug discovery to environmental monitoring and food safety, where rapid, low-cost, high-sensitivity detection is paramount. Emerging trends include hybrid plasmonic–photonic architectures, integration with complementary optical modalities and development of portable, user-friendly devices for point-of-care testing.

Research from Nature Portfolio

Recent studies have demonstrated that dispersion engineering of plasmonic nanogratings can quadruple the quality factor of SPR sensors compared with conventional prism-based systems. By tailoring grating periodicity and absorptive elements adjacent to the metal film, these devices achieve enhanced field localisation and a negligible resonance wavelength shift across variable incident angles. In parallel, large-scale topographically patterned metal films fabricated via combined nanoimprint and soft-lithography techniques have enabled perpendicular transmission SPR sensing. These high-throughput nanostructures exhibit sharp resonances with full-width at half-maximum of around 15 nm and one-order-of-magnitude improvements in optical transmission. Integration with microfluidic channels has validated real-time, label-free monitoring of protein–protein interactions, paving the way for robust, instrument-free biosensing platforms.

Research from all publishers

A comprehensive review of SPR-based biodetection systems has synthesised recent progress in sensor chip materials, nanostructure integration and hybrid detection schemes. It emphasises innovations in multiplexed assay formats, cost-effective fabrication and device miniaturisation for point-of-care applications, as well as the extension of plasmonic sensing to environmental toxin analysis. Separately, optimisation of silver-based grating couplers on silicon-oxide substrates has yielded stable, long-term plasmonic structures. Through combined theoretical modelling and experimental validation, these grating sensors achieve high sensitivity over a biologically relevant refractive index range (1.32–1.46) with values approaching 129° per refractive index unit. This work underscores the role of precise structural parameter tuning in enhancing reliability and analytical performance.

Plasmonic Sensing Techniques in Optical Biosensors publication trend

The graph below shows the total number of articles in plasmonic sensing techniques in optical biosensors across all publications each year (not limited to Nature Index journals).

Technical terms

Surface Plason Resonance (SPR): Resonant excitation of delocalised electron oscillations at a metal–dielectric interface, sensitive to refractive index changes.

Localized Surface Plason Resonance (LSPR): Confinement of plasmonic oscillations within metal nanoparticles or nanostructures, leading to intense local electromagnetic fields.

Kretschmann configuration: A prism-coupled geometry in which light undergoes total internal reflection to excite surface plasmons on an adjacent metal film.

Nanograting: A periodic arrangement of metallic or dielectric lines at the nanoscale, used to couple light into surface plasmons or manipulate dispersion.

Refractive Index Unit (RIU): A dimensionless measure of refractive index change, used to quantify sensor sensitivity.

References

1. Dispersion engineering with plasmonic nano structures for enhanced surface plasmon resonance sensing. Scientific Reports (2018).
2. Topographically Engineered Large Scale Nanostructures for Plasmonic Biosensing. Scientific Reports (2016).
3. Grating-Coupled Surface Plasmon Resonance (GC-SPR) Optimization for Phase-Interrogation Biosensing in a Microfluidic Chamber. Sensors (2018).
4. Surface Plasmon Resonance-Based Biodetection Systems: Principles, Progress and Applications—A Comprehensive Review. Biosensors (2025).
5. Optimizing Stability and Performance of Silver-Based Grating Structures for Surface Plasmon Resonance Sensors. Sensors (2023).