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In this paper, we propose a spectrally-resolved titanium dioxide waveguide resonant sensor, modified with a perovskite film. The sensor consists of a prism (N-FK51A), gold (Au), hybrid organic–inorganic halide perovskites, and titanium dioxide layers. The thickness of each layer and the incident angle were optimized based on the Fresnel equations. The refractive index sensitivity of the sensor increased by 32.1% and the figure of merit improved by 60.0% after optimizing the thickness of each layer. The optimized sensor was applied to detect five types of cancer biomarkers (Basal, HeLa, Jurkat, PC12, and MDA-MB-231). Simulation results at an incident angle of 14° demonstrate that the sensor shows excellent performance for the proposed cancer biomarkers, with resonance wavelength shifts ranging from 26 to 44 nm due to differences in the refractive indices between normal cell and cancer cell. These results indicate that the perovskite-modified sensor offers superior sensitivity compared to conventional sensors without the perovskite structure. This enhancement significantly improves the detection performance across various cancer biomarkers. Additionally, by replacing the dense titanium dioxide film with a nanoporous structure in the waveguide layer, which also acts as a biochemical molecule enrichment layer, the detection sensitivity for low-concentration small molecules in solution can be further enhanced. The adsorption sensitivity for small molecules is 90 nm per unit volume fraction. [ABSTRACT FROM AUTHOR]

The apparent enhancement of spectral resolution is one of the attractive features of two-dimensional correlation spectroscopy (2D-COS). Highly overlapped adjacent bands often encountered in one-dimensional spectra may be effectively differentiated and identified by spreading peaks along the second dimension. This differentiating feature or selectivity is especially prominent in asynchronous spectra, where even a slight difference in the variation patterns of overlapped bands in response to a given perturbation results in the generation of cross-peaks. While cross-peaks in asynchronous spectra can identify signals originating from different moieties or bands, they do not effectively specify which regions of spectra actually share the same molecular origin. Overreliance on asynchronous spectra alone risks the potential false negative assessment or lack of sufficient specificity, leading to the failure of classifying signals into a reasonable set of component groups. The combined use of synchronous and asynchronous spectra coupled with the scaling techniques, elimination of anti-correlated negative synchronous peaks, and a robust line shape narrowing method provides a means to achieve both selectivity and specificity for resolution-enhancement of 2D-COS. [ABSTRACT FROM AUTHOR]