Table 3.

Key Comparison Between SPR and LSPR Based Biosensors

Category	SPR Biosensors	LSPR Biosensors
Operating Principle	Measures bulk refractive index changes over a continuous metal film using propagating surface plasmons	Relies on localized oscillations of conduction electrons in metal nanoparticles (NPs)
Sensitivity & Detection Limits	Highly sensitive, fM-pM detection range	Moderate to high sensitivity, pM-nM detection range
Fabrication Techniques	Electron Beam Lithography (EBL), Nanoimprinting (NIL), DC Sputtering, Thermal Evaporation – Requires cleanroom facilities, high-end instrumentation	Hydrothermal Synthesis, Drop Casting, Self-Assembly, Electrostatic Adsorption – Lower-cost, scalable but may affect reproducibility
Materials Used	Gold (Au) standard due to chemical inertness and conductivity; Graphene, MoS2, Perovskites used for hybrid structures	Silver (Ag) preferred for stronger plasmonic resonance but prone to oxidation; ZnO nanowires, polymer coatings (PDMS, polydopamine) enhance stability
Cost & Scalability	Expensive, complex fabrication, high operational cost; bulk optical setup limits portability	Lower-cost, highly scalable, ideal for resource-limited settings and POC applications
Application Areas	Cancer biomarker detection, Protein binding kinetics, Viral diagnostics (Dengue, HIV, EBV), Pharmaceutical research	Rapid infectious disease screening (Dengue, HIV, Prostate Cancer), Personalized medicine, Field diagnostics
Strengths	High precision, low detection limits, robust clinical diagnostics	Portable, real-time monitoring, label-free, cost-effective fabrication
Limitations	Requires bulk optical components, costly, complex fabrication	Lower batch-to-batch reproducibility, slightly less sensitive than SPR
Future Trends	Hybrid SPR-LSPR biosensors, AI-integrated spectral analysis, multiplexed biomarker detection, wearable plasmonic sensors	Flexible, miniaturized biosensors, smart diagnostics, integration with IoT for real-time monitoring