Development of artificial latent fingerprint solution using a novel lipid composition and printing

Latent fingerprint research requires reproducible test materials that realistically mimic natural prints for the evaluation of development techniques. This study presents a novel artificial latent fingerprint solution that incorporates lipid components derived from the human body, simulating the composition of natural sweat and sebum, and combines them with traditional amino acid-based solutions. To improve solubility of non-polar lipid molecules, a 1:1 (v/v) mixture of n-hexane and isopropyl alcohol was used as the solvent, and the solution was loaded into printer cartridges to deposit standardized fingerprint-sized images on A4 paper, OHP film, and thermal paper. Development was carried out using established reagents, including ninhydrin, 1,2-indandione (1,2-IND), oil red O (ORO), and nile red (NR) for porous substrates; cyanoacrylate (CA) fuming with basic yellow 40 (BY 40), black, and fluorescent powders for nonporous substrates; and ThermaNin^®, 1,2-IND + polyvinylpyrrolidone (1,2-IND + PVP), ORO, and NR for thermal paper. The artificial prints showed broad compatibility across porous, nonporous, and thermal surfaces. Clear ridge detail and identifiable minutiae were consistently observed with most reagents, although NR exhibited limited fluorescence. All developed prints were identical, ensuring reproducibility for controlled testing. These findings demonstrate that the proposed solution provides a realistic and standardized tool for forensic validation of fingerprint development methods, including challenging substrates such as thermal paper.