Fig. 2: Gold nanoparticle-based plasmonic chip utilized in the pre-diagnostic platform.

A Realization of plasmonic chips based on nanoparticle immobilization on a glass substrate using a synthesis and chemical modification method. B Experimentally obtained plasmonic resonance supported by the synthesized gold nanoparticles (T = Optical transmission). The inset in the figure shows the photograph of a plasmonic chip. C Cross-sectional electric field profile calculated at the plasmonic resonance. D Electric field profile calculated at z = z’ (highlighted with a white dashed line in Fig. 2C) along the xy-plane. The figure displays the propagation (k) and polarization (E) directions of the incident light source. E Schematic illustration of the constituent elements of the chip-preparation apparatus. F Photograph of the chip-preparation apparatus with a glass slide sandwiched inside. G SEM image of the gold nanoparticles bounded on the glass surface. H Zeta Sizer results demonstrating particle distributions based on diameter. Figure inset shows the substrate surface covered with gold particle (highlighted with green), demonstrating a 66.33% coverage ratio. I Variations within the resonance wavelength (λ, left) and the linewidth (full-width half-maximum - FWHM, middle) of the transmission resonance supported by n = 50 plasmonic chips with different surface coverage ratios (right). The box plot represents the interquartile ranges, and the black squares are the average values of the data. J Variations in the spectral position (λ, black) and the linewidth (orange) of n = 10 plasmonic chips over a 24-month period. In the figure, squares correspond to the mean values and the error bars represent double the standard deviation.