Application of Fluorescent Carbon Nanoelectronic Materials in Combining Partial Differential Equations for Fingerprint Development and Its Image Enhancement

Fluorescent developers play a crucial role when dealing with objects with complex patterns or color interference against their background due to their excellent photoluminescent properties. In recent years, fluorescent nanoelectronic materials have emerged as a novel class of fluorescent materials for fingerprint development research. Here, carbon quantum dots (CQDs) are synthesized using an electrochemical method and utilized as fluorescent nanoelectronic materials in combination with gold nanoparticles (AuNPs) to form a composite (Au/CQDs). The photoelectric properties of Au/CQDs are verified, and a precursor solution for Au/CQDs is prepared using the Wessling method. After the addition of a surfactant and subsequent elimination processes, an Au/CQDs fluorescent nanocolloidal solution is obtained. This solution is applied for the development of visible fingerprints and latent fingerprints on adhesive surfaces. The resulting development images are subjected to enhancement processes such as sharpening, smoothing, and noise reduction using partial differential equations to improve their visual quality. In experiments, under light exposure, Au/CQDs exhibit a higher conversion rate with cyclohexane compared to conditions without light. In the Au/NPs system, the fluorescence of CQDs is effectively quenched due to the rapid electron transfer process within the Au/CQDs system. Moreover, the electrode modified with Au/CQDs shows significantly improved efficiency in decomposing H2O2 compared to conditions without light exposure. After the development with Au/CQDs nanoparticle colloid solution, bright fingerprint patterns are visible under ultraviolet light. As the age of the fingerprint increases, the developed fingerprint has a higher resolution than fresh fingerprints. Image enhancement through partial differential equations results in satisfactory sharp edges and smooth contours in the images.