High‑Surface‑Sensitive Self‑Referenced Plasmonic Sensor Based on Au Nanoislands

Resumen

We present a self-referenced plasmonic sensor with a high surface sensitivity based on Au nanoislands synthesized by thermaldewetting on a planar SiO2/metal bilayer deposited on a Si chip. The optical device displays two spectral features in reflection: a Fabry-Perot resonance due to the SiO2/metal bilayer and a localized surface plasmon resonance (LSPR) associated with the Au nanoislands, serving as a reference and sensing signal, respectively. Surface sensitivity was investigated through the study of bovine serum albumin protein adsorption. The device exhibited a surface sensitivity of 0.2 nm/(ng/cm2), an order of magnitude greater than other plasmonic devices based on Au nanoislands. The device response was theoretically modeled using rigorous coupled-wave analysis (RCWA) simulations, which showed strong agreement with the experimental results and provided design guidelines for further sensitivity improvement. The combination of high surface sensitivity, chip-based architecture, cost-effectiveness, and a straightforward Au nanostructure synthesis procedure positions this device as a promising self-referenced plasmonic sensor for biosensing applications.