Improved Sensitivity of Localized Surface Plasmon Resonance Transducers Using Reflection Measurements

Area of Science:

• * Nanophotonics and Plasmonics
• * Surface Science and Engineering
• * Optical Sensing Technologies

Background:

• * Localized Surface Plasmon Resonance (LSPR) is a phenomenon exploited in optical biosensors.
• * Refractive Index Sensitivity (RIS) quantifies the LSPR transducer's performance.
• * Gold nanoparticles (Au NPs) are commonly used LSPR transducer materials.

Purpose of the Study:

• * To investigate and compare the Refractive Index Sensitivity (RIS) of gold nanoparticulate films.
• * To evaluate the influence of measurement mode (transmission vs. reflection) on RIS.
• * To determine the optimal configuration for enhanced LSPR sensing.

Main Methods:

• * Fabrication of gold island films via evaporation and annealing.
• * Immobilization of gold nanoparticle (Au NP) films.
• * Measurement of LSPR spectra in solvents with varying refractive indices (RI).
• * Quantification of RIS based on wavelength shifts in transmission and reflection modes.

Main Results:

• * Both evaporated/annealed and immobilized Au NP films exhibit LSPR.
• * Refractive Index Sensitivity (RIS) was successfully measured in both transmission and reflection modes.
• * RIS was found to be significantly higher when measured in reflection mode compared to transmission mode.

Conclusions:

• * Reflection mode measurements offer superior Refractive Index Sensitivity (RIS) for LSPR transducers.
• * The choice of measurement mode critically impacts the performance of LSPR-based sensors.
• * Utilizing reflection mode can lead to more sensitive and effective refractive index sensing applications.