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A π-Configuration Plasmonic Dual Surface Plasmon Resonance Fiber Optic Sensor for Multi-Analyte Detection
John Ehiabhili1, Radhakrishna Prabhu1, Somasundar Kannan1
1School of Computing and Engineering Technology, Robert Gordon University, Aberdeen AB10 7GJ, UK.
Sensors (Basel, Switzerland)
|June 26, 2026
Summary
This study introduces a novel Pi (π)-configured dual surface plasmon resonance (SPR) optical fiber sensor for simultaneous multi-analyte detection. The innovative design enhances biosensing capabilities by utilizing asymmetric metallic and hybrid thin films for improved sensitivity and resolution.
Area of Science:
- Photonics and Biosensing
- Nanomaterials and Thin Film Technology
- Optical Fiber Sensor Technology
Background:
- Conventional optical fiber surface plasmon resonance (SPR) sensors offer real-time, label-free detection but are limited in multi-analyte capabilities.
- Existing designs often struggle with simultaneous detection of multiple analytes due to spectral overlap or limited resolution.
Purpose of the Study:
- To design and simulate a novel Pi (π)-configured dual SPR optical fiber sensor for enhanced simultaneous multi-analyte detection.
- To investigate the use of asymmetric metallic (Ag, Au, Cu) and hybrid (metal + TiO2) thin films for improved sensing performance.
- To achieve distinct resonance peaks with high spectral separation for multiplexed sensing applications.
Main Methods:
- Utilized a π-configuration with two opposing side-polished surfaces on an optical fiber for plasmonic excitation.
- Employed asymmetric metallic and hybrid thin films (Ag, Au, Cu, Ag-TiO2, Au-TiO2, Cu-TiO2).
- Performed numerical simulations using the finite element method (FEM) in COMSOL Multiphysics v6.3 to analyze optical properties and sensitivity.
Main Results:
- Achieved dual resonance dips with significant spectral separation (>125 nm) for all tested film configurations.
- Demonstrated high wavelength sensitivity, with Ag-TiO2 films reaching 20,000 nmRIU⁻¹ and Ag films reaching 12,600 nmRIU⁻¹.
- Confirmed resolvable dual-analyte detection with minimized crosstalk due to sufficient spectral separation.
Conclusions:
- The π-configured dual SPR optical fiber sensor design enables simultaneous multi-analyte detection with enhanced versatility.
- Optimized metallic and hybrid nanostructured films provide distinct dual peaks, high sensitivity, and improved refractive index resolution.
- This breakthrough offers potential for advanced multiplexed biosensing in medical diagnostics, environmental monitoring, and chemical detection.
