Recognition of Latent Fingerprints and Ink-Free Printing Derived from Interfacial Segregation of Carbon Dots

Abstract

Carbon dots (CDs) have attracted increasing interest in recent years owing to their desirable properties. Despite the availability of diverse elaborate CDs, the function and application of CDs are far to be fully exploited. Here, biomass-derived carbon dots dispersed in a polymer matrix are found to behave as ink-free patterned substrates, which are demonstrated to be useful for nondestructive collection and recognition of latent fingerprints (LFPs), as well as printing. The coating of CD/poly(vinyl alcohol) solution on a LFP yields a flexible transparent film; a stable fluorescent fingerprint with clear ridge details enabling personal identification is formed on this film. Encouragingly, this method can be applied to nondestructively lift and recognize long-timely exposed LFPs from various surfaces. The mechanism for LFP collection and visualization is proposed, which should be ascribed to the interfacial segregation of CDs in the polymer matrix during the film forming process. This mechanism is further validated by and utilized for application of CD/polymer composites in relief printing, intaglio printing, and micro-trace transferring.

Green synthesis of water-soluble fluorescent carbon dots from rosemary leaves: Applications in food storage capacity, fingerprint detection, and antibacterial activity

“…The banana experiment was conducted using process similar to that in the literature. 64 PVA (25 g) and pure water (130 mL) were mixed and heated to 98 °C and magnetically stirred. Next, about 10 g of a CD aqueous solution was added.…”

Fluorescent Carbon Dots Ink for Gravure Printing

“…Highly dispersible in water CDs were easily mixed homogenously with water-based specific resins, and the final product was printed on several substrates (e.g., paper and plastic) or deposited on glass, with high homogeneity, and showed excellent photoluminescence, which remained after the evaporation of the solvent, in the solid printed material. Up to now, there are only a few reports in the literature that have used fluorescent inks for printing methods, most of them for anti-counterfeiting applications [19][20][21][22][23][24][25][26]. However, for the first time, CDs are used for the preparation of gravure printing ink.…”

The Rapid and Large‐Scale Production of Carbon Quantum Dots and their Integration with Polymers

“…CD/polymer solutions have been demonstrated to have promising applications as printable fluorescent inks for creating multicolor fluorescent patterns by direct writing, [94] photoetching, [40] silk‐screen printing, [29, 59] relief printing, [20] intaglio printing, [20] and electrodepositing technology [91] . These patterns are nearly colorless in sunlight, but emit multicolor fluorescence under UV light.…”