Characterization of electrochemically visualized latent fingerprints

Abstract This work presents an electrochemical approach to the visualization of fingerprints on brass cartridges with the aim of characterizing how visualization using polyphenazine dyes affects latent fingerprints. After visualization using cyclic voltammetry and chronoamperometry, the individual layers (substrate/fingerprint/polymer film) and their interfaces were characterized profilometrically, spectroscopically by Fourier transform infrared spectroscopy (FT-IR) and via scanning electron microscopy (SEM). The morphology and surface quality observed by SEM revealed the size of the particles formed from both electrochemically deposited polymer films. Profilometry showed the homogeneity and surface roughness of the deposited layers. It was found that poly(toluidine blue) forms a thinner homogeneous layer with better adhesion to the brass substrate than the poly(neutral red) film. Based on the FT-IR spectra, it can be concluded that the polymer films of the dyes were deposited on the surface of the substrates as a result of the observed changes and band intensities belonging to the mono- and polymer forms of neutral red and toluidine blue, respectively. The electrochemical visualization method proved to be effective, gentle, and relatively fast. Graphical Abstract