Non-destructive enhancement of latent fingerprints on stainless steel surfaces by electrochemiluminescence

Abstract

Visualization and detection of latent fingerprints (LFPs) on metal surfaces are of highly practical importance, e.g., in identifying gun cartridges. We report herein the visualization of LFPs on stainless steel surfaces by electrochemiluminescence (ECL). Since organic residues, such as fatty acids, in the fingerprint deposit make the underlying surface electrochemically inert or less active, an ECL reaction occurs only on the metal portions untouched by the fingertip, hence generating a negative image of the fingerprint. The popular ECL reaction solution, consisting of ruthenium(ii) tris(2,2'-bipyridyl) and tri-n-propylamine, was used for this imaging purpose. Factors, including the applied potential and the concentration of ECL luminophore, as well as the stability of ECL negative images, were investigated to achieve a satisfactory visualization enhancement. This imaging approach is simple, rapid, non-invasive, and no pre-treatment either on the background or on the fingerprint itself is needed. It constitutes a powerful tool for visualizing LFPs on metal surfaces. This method was also demonstrated to be suitable for enhancing LFPs collected from various surfaces.

Exposing latent fingermarks on problematic metal surfaces using time of flight secondary ion mass spectroscopy

“…Xu et al [29] have also proposed a technique for the visual enhancement of sebaceous latent fingermarks by electrochemiluminescence (ECL) which gave a satisfactory visual contrast. In addition to this, scanning electrochemical microscopy (SECM) [30], scanning Kelvin microprobe [31,32] and electrostatic deposition [24,25] techniques have also been reported to visualise identifiable latent fingermarks on metal surfaces.…”

Advances in the development and component recognition of latent fingerprints

“…Recently, our group developed an electrochemiluminescence (ECL) imaging method for visualizing LFPs by the spatially selective control of the location of ECL generation (Figure 1), using Ru(bpy) 3 2 [46] or rubrene [47] as the ECL luminophore. This method is particularly useful in visualizing LFPs on metal surfaces, e.g., stainless steel [48], that are often found in felony cases. Recently, Tan et al [49] demonstrated the visualization of oily LFPs and in situ detection of TNT in fingerprints by using an ECL-based image-contrast technology on the surface of porous silicon.…”

Future prospects of luminescent nanomaterial based security inks: from synthesis to anti-counterfeiting applications

“…In electrochemiluminescence, the light 45 emitting species are formed near the electrode surface which offers approach for imaging electrochemical or biosensing events. 330 In their study, they produced a negative image of fingerprint using electrochemiluminescence. Fig.…”