Synthesis, properties, and forensic applications of titanium dioxide nanoparticles in latent fingerprint development

Fingerprints are major evidence that helps establish a link between a crime and its perpetrator. There are multiple techniques available for developing latent fingerprints, and recent studies show that nanoparticles are among the best methods due to their excellent properties and surface area. In this study, Titanium dioxide nanoparticles (TiO₂ NPs) were synthesized using the sol-gel technique. Characterization of the NPs was performed using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy. Fingerprints were developed on 10 different surfaces, including ceramic, wood, paper, plastic, cardboard, glass, fiber, aluminum foil, thermocol, and metal. The synthesized TiO₂ nanopowder produced clearly identifiable prints on all substrates examined. Fingerprints on the glass surface had the highest clarity, whereas on the ceramic surface, they had the lowest. The clarity percentage ranged from 60% to 100%. The results showed an average clarity of 90.83% on non-porous surfaces, 70.00% on porous surfaces, and 95.00% on the semi-porous surface (paper). Clarity was scored independently by three fingerprint examiners against a predefined clarity index, and the reported values represent the mean of these assessments pooled across aging intervals of 1 h, 1 day, and 5 days. The efficiency of various nanoparticles used to develop fingerprints has also been compared with that of TiO₂ nanoparticles. The particle morphology and size of the synthesized TiO₂ NPs, together with substrate porosity, are proposed as the factors governing adhesion to fingerprint residues and the resulting quality of ridge-detail development, consistent with trends reported for other nanoparticle powders.