1：Experimental Design and Method Selection:

TiO2 thin films were deposited using a modified spray pyrolysis technique with varying precursor concentrations (0.075 M, 0.1 M, 0.125 M) of titanium trichloride solution. Other parameters like deposition temperature (350 °C), spray time (20 min), and nozzle-to-substrate distance (30 cm) were kept constant. Films were annealed at 500 °C for 2 hours for oxidation and crystallization.

2：075 M, 1 M, 125 M) of titanium trichloride solution. Other parameters like deposition temperature (350 °C), spray time (20 min), and nozzle-to-substrate distance (30 cm) were kept constant. Films were annealed at 500 °C for 2 hours for oxidation and crystallization. Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Glass substrates were used for deposition. Precursor solutions were prepared by diluting standard TiCl3 solution (Sigma Aldrich) in double-distilled water.

3：List of Experimental Equipment and Materials:

Equipment includes a spray pyrolysis setup, BRUKER D8 ADVANCE diffractometer for XRD, JEOL-540LV microscope for SEM, UV–vis spectrophotometer for optical studies, and MEXTECH M288CTHW humidity meter for sensing measurements. Materials include TiCl3 solution, glass substrates, and distilled water.

4：Experimental Procedures and Operational Workflow:

Films were deposited by spraying precursor solutions onto heated substrates, followed by annealing. Structural analysis was done via XRD, surface morphology via SEM, optical properties via UV–vis spectroscopy, and humidity sensing by measuring resistance changes with relative humidity.

5：Data Analysis Methods:

Crystallite size, microstrain, dislocation density, and texture coefficient were calculated from XRD data using Scherrer formula and other relationships. Band gap was determined from UV–vis spectra. Sensitivity, response time, and recovery time were calculated from resistance measurements.