Universidad Politécnica de Madrid
“A Self-Referenced Refractive Index Sensor Based on Gold Nanoislands”

CEMDATIC's researchers have published a new article presenting an innovative structure that can be employed as a refractive index sensor

We report on a self-referenced refractive index optical sensor based on Au nanoislands.
The device consists of a random distribution of Au nanoislands formed by dewetting on a planar
SiO2/metal Fabry–Pérot cavity. Experimental and theoretical studies of the reflectance of this
configuration reveal that its spectral response results from a combination of two resonances: a localized
surface plasmon resonance (LSPR) associated to the Au nanoislands and the lowest-order
anti-symmetric resonance of the Fabry–Pérot cavity. When the device is immersed in different fluids,
the LSPR contribution provides high sensitivity to refractive index variations of the fluid, whereas
those refractive index changes have little impact on the Fabry–Pérot resonance wavelength, allowing
its use as a reference signal. The self-referenced sensor exhibits a spectral sensitivity of 212 nm/RIU
(RIU: refractive index unit), which is larger than those of similar structures, and an intensity sensitivity
of 4.9 RIU􀀀1. The proposed chip-based architecture and the low cost and simplicity of the Au
nanoisland synthesis procedure make the demonstrated sensor a promising self-referenced plasmonic
sensor for compact biosensing optical platforms based on reflection mode operation.

Full article: https://doi.org/10.3390/s23010066