Fe₃O₄/RhB Nanocomposite as a Dry Magnetic Powder for Fingerprint Detection

Abstrak

The increasing crime rate in Indonesia highlights the need for reliable forensic technologies, particularly for latent fingerprint identification. Conventional dusting powders often exhibit low contrast, limited durability, and potential risks of damaging evidence, especially on porous or complex surfaces. This study aimed to synthesize and characterize an Fe₃O₄/Rhodamine B (RhB) nanocomposite and evaluate its potential as a dry magnetic powder for latent fingerprint detection. Fe₃O₄ was extracted from natural iron sand and combined with RhB through a hydrothermal method. The resulting material was characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). FTIR analysis confirmed the characteristic functional groups and interactions between Fe₃O₄ and RhB. XRD revealed a cubic magnetite spinel structure, with the lattice parameter decreasing from 8.394 Å to 8.373 Å following composite formation. SEM analysis showed agglomerated particles with an average size of 91.58 nm and relatively uniform RhB distribution. Practical testing demonstrated that the Fe₃O₄/RhB nanocomposite produced magenta-colored fingerprints with enhanced contrast, enabling clearer visualization of ridges, valleys, bifurcations, and terminations than pure Fe₃O₄. These findings indicate that the nanocomposite has potential as an effective magnetic dusting powder for latent fingerprint detection in forensic investigations.