Latent Fingermarks Enhancement in Deep Eutectic Solvent by Co-electrodepositing Silver and Copper Particles on Metallic Substrates

A facile and rapid method for visualizing latent fingermarks (LFMs) on various commonly encountered metallic substrates has been first developed in deep eutectic solvent by utilizing spatially selective co-electrochemical deposition of silver and copper particles. This strategy exploited the LFM residua as an insulating mask and the silver and copper particles were only deposited onto the bare surfaces and the valleys between the papillary ridges on the substrates. As a result, a high contrast negative visualization of LFM that can clearly provide clear ridge minutiae details of the LFMs was obtained under the optimized conditions of electrochemical deposition (applied potential, deposition time and the concentration and ratio of electroplating solution), which demonstrated a promising tool in routine forensic application.