A π-Configuration Plasmonic Dual Surface Plasmon Resonance Fiber Optic Sensor for Multi-Analyte Detection
Year: 2026
Type: article
Abstract: Although optical fibre-based surface plasmon resonance (SPR) sensors have revolutionized real-time, label-free biosensing, conventional designs suffer from limited multi-analyte detection capabilities. This study utilizes the novel Pi (π)-configured dual-SPR optical fibre sensor with two opposing side-polished surfaces, enabling plasmonic excitation for simultaneous multi-analyte detection. The proposed sensor leverages asymmetric metallic thin films such as Ag, Au, Cu and hybrid configurations (metal + TiO₂) to generate two distinct resonance peaks, significantly enhancing detection versatility. Numerical simulations using finite element method in COMSOL Multiphysics v6.3 demonstrate that the π-configuration achieves dual resonance dips at 982 nm and 1276 nm for Ag and Ag-TiO₂ films, 1040 nm and 1317 nm for Au and Au-TiO₂ films, and 977 nm and 1249 nm for Cu and Cu-TiO₂ films respectively for an analyte refractive index of 1.42. A peak spec-tral separation >125 nm was achieved for all the sensors for a refractive index range of 1.37 – 1.42, ensuring that the two dips are resolvable since the change in SPR wavelength is greater than or equal to the full width at half maximum, preserving dual-analyte capability and minimizing potential crosstalk. Results indicate that the π-configured dual-SPR sensor utilizing silver and silver-TiO2 sensing layers had the highest wavelength sensitivity of 12,600 nmRIU-1 and 20,000 nmRIU-1 respectively, slightly outperforming its gold and cop-per counterpart. The optimized metallic and hybrid nanostructured films ensures dual distinct peaks with high sensitivity, while maximizing refractive index resolution. This work presents the design of a π-configured SPR-based optical fibre sensor utilizing dielectric and multi-metallic thin films, thereby offering a breakthrough in multiplexed biosensing for applications in medical diagnostics, environmental monitoring, and chemical detection.
Source: Sensors
DOI: 10.3390/s26123902
Institution: Robert Gordon University
Language: English
Topic: Advanced Fiber Optic Sensors
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,137
OpenAlex ID: W7165146019
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