1：Experimental Design and Method Selection:

The study involved preparing a porous silicon sample with a radial gradient in rugate reflectance band wavelength and two surface chemistries (methylated and oxidized). Hyperspectral and color imaging were used to monitor changes during vapor dosing with various solvents at different concentrations. Methods included electrochemical etching, surface modification, and multivariate data analysis.

2：Sample Selection and Data Sources:

A silicon wafer (Siltronix, B doped) was used to fabricate porous silicon samples. Solvent vapors (acetone, ethanol, heptane, 2-propanol, toluene) were generated at specified concentrations.

3：List of Experimental Equipment and Materials:

Equipment included a PAR EG&G Model 173 potentiostat/galvanostat, Tektronix AFG3021 function generator, KSL-1100X-S muffle furnace, Philips XL30S FEG SEM, Perkin Elmer Spectrum Two FT-IR spectrometer, KSV Cam 100 tensiometer, QICAM camera with Varispec LCTF, Point Gray Research Flea 2G and Flea 2-03S2M cameras, and an in-house vapor dosing system. Materials included HF, ethanol, iodomethane, polystyrene, and various solvents.

4：Experimental Procedures and Operational Workflow:

Porous silicon was prepared via electrochemical etching with a sinusoidal current. Surface modification involved thermal oxidation and electrochemical methylation. Hyperspectral and RGB images were collected during vapor dosing cycles, with data processed using Matlab for wavelength and hue analysis.

5：Data Analysis Methods:

Data were analyzed using principal component analysis (PCA) and linear discriminant analysis (LDA) in Matlab to discriminate between solvents and concentrations based on wavelength shifts and hue changes.