Visualization Of Latent Fingerprints Research Articles

Luminescence of a novel double-perovskite Sr2InSbO6:Eu3+ orange-red-emitting phosphor for white LEDs and visualization of latent fingerprints

Eu3+-activated Sr2InSbO6 (SISO) orange-red-emitting double-perovskite antimonate phosphors were realized. The emission spectrum of SISO:Eu3+ sample exhibited a strong orange-red emission band at 594 nm under 395 nm excitation. Judd-Ofelt theory analysis indicated the Eu3+ ions were in the symmetrical environment of SISO host lattice. The fabricated white light-emitting diode presents a high Ra and a good CCT. For the visualization of latent fingerprints (LFPs), the hydrophilic SISO:Eu3+ phosphor was converted into hydrophobic SISO:Eu3+@OA phosphor by coating oleic acid (OA). The SISO:Eu3+@OA phosphor could show reliable level 1–3 fluorescent images of LFPs with high contrast and resolution. The LFPs still exhibited the excellent visualization on the various substrates (glass, aluminum foil, stainless steel, compact disk, student card, and so on). These results indicate the SISO:Eu3+ products have great potential applications for WLEDs and visualization of LFPs.

Optimization of Electrochemical Visualization of Latent Fingerprints with Poly(Neutral Red) on Brass Surfaces.

This study is focused on the visualization of latent fingerprints on brass surfaces using the method of electrochemical deposition of a polymer film based on poly(neutral red) (PNR). The experiment included (i) optimization of conditions of electrochemical deposition of PNR on brass surfaces, (ii) ATR-FTIR spectroscopic characterization of PNR-modified substrates, and (iii) identification of characteristic details on visualized fingerprints on fired brass cartridges. For electrochemical visualization, it is necessary to keep in mind both kind and “story” substrates. Experimental findings showed that electrochemical visualization carried out on brass plates is a step forward before known findings described in the literature and gives simultaneously a new approach for criminalists in the fight against crime.

Surface modification of Mg2InSbO6:Eu3+ phosphors and applications for white light-emitting diodes and visualization of latent fingerprint

Due to outstanding optical characteristics of phosphors, they have recently been applied to various fields, such as solid-state lighting, forensic science, and laser technology. Herein, a series of Mg2InSbO6:xEu3+ (x = 0.005–0.25) phosphors with pure red emission were prepared via high-temperature solid-state reaction. Under near-ultraviolet 395 nm excitation, photoluminescence spectra of Mg2InSbO6:Eu3+ (MISO:Eu3+) phosphors exhibited a bright red luminescence peak at 612 nm, which is attributed to 5D0→7F2 transition of Eu3+. The thermal quenching temperature of the optimum sample exceeded 480 K, which is much higher than the working temperature of light-emitting diode (423 K). The packaged white light-emitting diode (WLED) had CIE coordinates of (0.336, 0.340) with correlated color temperature of 5322 K and color rendering index value of 90. Furthermore, the latent fingerprints (LFPs) stained with MISO:Eu3+ phosphors were visualized with level 1–3 features, but their accuracy was relatively low. Therefore, oleic acid (OA) was utilized to form a hydrophobic coating on MISO:Eu3+ powders to improve fingerprint development, and the higher accuracy of level 1–3 features was achieved, especially level 3 features. The LFPs on smooth and rough surfaces stained with MISO:Eu3+@OA phosphors were easily collected at high contrast under 395 nm light. The obtained results prove that MISO:Eu3+ and MISO:Eu3+@OA can be considered as promising red phosphors for WLED and LFP identification and provide insight into the improvement of LFP development.

Visualization of latent fingermarks on fabric using multi-metal deposition (MMD)—A preliminary study

Multi-metal deposition (MMD) is a versatile fingermarks detection technique adapted from the colloidal gold biolabeling. However, the tedious procedures of MMD makes it receive little attention compared with other methods. The aim of this study is to evaluate the efficacy of MMD technique on several common fabrics, which is considered notoriously challenging for latent fingermark detection. Four different MMD formulations were examined to process fingermarks deposited on nylon taffeta, polyester taffeta, polyester pongee and cotton sateen to determine the most suitable one and the influence of aging and water immersion were also determined through subsequent experiments. It was found that MMD I outperformed other three formulations and obtained excellent results on nylon taffeta, polyester taffeta and satin ribbon, with polyester taffeta and satin ribbon providing more than 30% of identifiable marks even for fingermarks aged over 28 days. Cotton sateen and oxford cloth failed to produce ridge details but evidence of “touch” were successfully visualized, which may contribute to further DNA extraction. Water immersion did have some observable influence on the quality of detected marks as part of the MMD reactant within fingermarks lost during immersion, but the result from nylon taffeta and satin ribbon is still satisfying with the percentage of marks scored 3 and 4 reached 30%. The result of this study confirmed the capability of MMD I in treated with fingermarks on several kinds of fabrics, and shows potential to promote this non-instrumentation dependent technique.

Aggregation induced emission based active conjugated imidazole luminogens for visualization of latent fingerprints and multiple anticounterfeiting applications

Aggregation-induced emission based organic heterocyclic luminogens bearing conjugated electronic structures showed much attention due to its excellent fluorescence in aggregation state. In this communication, a novel conjugated blue light emitting imidazole molecule is synthesized by one pot multicomponent reaction route is reported for the first time. The prepared molecule exhibits a strong fluorescence in aggregation state with exceptional properties, such as high purity, inexpensive, eco-friendly, large scale production, high photostability, etc. By considering these advantages, a new fluorescence based platform has been setup for in-situ visualization of latent fingerprints and its preservation by spray method followed by Poly(vinyl alcohol) masking. A clear and well defined fluorescence fingerprint images are noticed on variety of surfaces by revealing level 1–3 ridge features upon ultraviolet 365 nm light exposure. The dual nature of binding specificity as well as excellent fluorescence properties permits the visualization of latent fingerprints for longer durations (up to 365 days) with superior contrast, high sensitivity, efficiency, selectivity and minimal background hindrance. We further fabricated unclonable invisible security ink for various printing modes on valuable goods for protection against forging. The developed labels are displaying uniform distribution of ink and exceptional stability under various atmospheric environments. The development of long preservative information using aggregation-induced emission based luminogen opens up a new avenue in advanced forensic and data security applications.

Synthesis and photophysical behavior of fluorescent benzazole dyes and fluorescent microparticles: Their use as fingerprint developer

Novel benzazole derivatives were synthesized and their photophysical properties were determined experimentally in different types of solvents also by theoretical calculations using Density Functional Theory (DFT). The results of the theoretical computational studies were well consistent with those observed experimentally, evidencing the type of electronic transitions that occurs between the frontiers orbitals. All synthesized derivatives are highly fluorescent in the violet-green region (363–536 nm) under ultraviolet light of 365 nm with large Stokes shift due to excited state intramolecular proton transfer (ESIPT) mechanism. Furthermore, the thermogravimetric and differential thermogravimetric analysis showed their good thermal stability, with decomposition temperature up to 250 °C. The fluorescent benzazole derivative was successfully entrapped into starch-based microparticles and applied for visualization of latent fingerprints on different types of surfaces common to forensic cases (metal, plastic, paper, wood, and ceramic).

A facile construction of bifunctional core-shell magnetic fluorescent Fe3O4@YVO4:Eu3+ microspheres for latent fingerprint detection

Latent fingerprint recognition technique has received increasing attention because it helps to precisely identify human information for many applications. In this study, bifunctional core-shell magnetic fluorescent microspheres have been synthesized via a facile interface Pechini-type sol-gel method using citric acid and polyethylene glycol as chelating agent and cross-linking agent, respectively. The obtained Fe3O4@YVO4:Eu3+ microspheres possess a typical core-shell structure, large magnetization, and strong fluorescence emission. The surface morphology and roughness of the microspheres can be flexibly tuned by controlling the multistep interface deposition process and subsequent calcination temperatures. Due to their well-integrated bifunctionalities, these magnetic fluorescent microspheres show outstanding performance in the visualization of latent fingerprints on various substrates with high definition and excellent anti-interference, and therefore they have great potential for application in identity recognition.

Ultrahigh stable lead halide perovskite nanocrystals as bright fluorescent label for the visualization of latent fingerprints

Fingerprints formed by the raised papillary ridges are one of the most important markers for individual identification. However, the current visualization methods for latent fingerprints (LFPs) suffer from poor resolution, low contrast, and high toxicity. In this work, the CsPbBr3/Cs4PbBr6 nanostructured composite crystal (CsPbBr3/Cs4PbBr6 NCC) were synthesized via a simple chemical solvent-assisted method. Compared with conventional perovskites, the as-prepared CsPbBr3/Cs4PbBr6 NCC present an outstanding long-term environmental and water stability with 42% and 80% photoluminescence intensity remaining after 28 d under water and air conditions, respectively. Moreover, a special response to biomolecules from fingerprints was observed due to the hydrophobic interactions between the CsPbBr3/Cs4PbBr6 NCC surface hydrophobic ligands (oleyl amine and oleic acid) and the hydrophobic groups in the biomolecules from the human fingers. Clear LFPs images were visualized in a bright environment illuminating the prepared CsPbBr3/Cs4PbBr6 NCC powder under UV light of wavelength 365 nm. The images were also obtained on porous and non-porous surfaces such as metal, plastic, wood, glass, and paper products. These perovskite nanocrystals are expected a stable and bright luminescent labeling agent for LFPs visualization and have potential application in crime scene and personal identifications.

Ultrasensitive luminescent turn-on detection of perchlorate particulates by triggering supramolecular self-assembly of platinum(II) complex in hydrogel matrix

Onsite ultrasensitive identification of the airborne or deposited perchlorate particulates is crucial for homeland security, forensic analysis, and environment monitoring. However, few of the currently developed luminescent sensor focus on the direct and ultratrace detection of its solid particulates as the low level of analyte and the difficulty in exhaustive collection of the trace sample. Here, a general design strategy for the direct, ultrasensitive, and specific luminescent turn-on sensing of perchlorate particulates is proposed by triggering supramolecular self-assembly of cationic platinum(II) complex in a hydrogel matrix, in which the self-assembly of platinum(II) complex endows the luminescence turn-on response and the hydrogel matrix creates excellent confinement effect for terminating the diffusion of generated luminescent 1D aggregates. The proposed hydrogel-based sensor is capable to detect the airborne perchlorate particulate of 1.12 ng by naked eye and 0.11 fg by common optical microscope. Further practical sensing performances for real firecracker and buried perchlorate in soil demonstrates the excellent environmental adaptability, and the latent fingerprint visualization shows great potential for clue tracking. This study provides an inspirable strategy for designing ultrasensitive luminescent sensor for trace solid sample.

Surface functionalized inorganic phosphor by grafting organic antenna for long term preservation of latent fingerprints and data-security applications

Creative advancements are enormously sought for the advanced forensic and data security in modern era. Herein, fabrication of Bovine Serum Albumin (BSA) functionalized Gd2O3:Eu3+ (5 mol %) nanopowders dispersed in a poly(vinyl alcohol) (PVA) matrix for long term preservation and visualization of latent fingerprints, as well as printing. Efficient intramolecular energy transfers from coordinated ligand to the doped Eu3+ ions, called the antenna effect was precisely organized by grafting organic molecule, resultant to an enhanced photoluminescence emission. On this basis, the masking of PVA/Gd2O3:Eu3+ (5 mol %)@BSA solution on a latent fingerprints results a flexible transparent film; a highly stable fingerprint images with well-defined ridge characteristics was developed on the film, which enabling personal individualization. Interestingly, the followed latent fingerprints development technique was non-destructive and stored long duration up to 1 year on filtrating and non-filtrating surfaces. The same mechanism was also validated by utilized for application of PVA/Gd2O3:Eu3+ (5 mol %)@BSA nanocomposites in dip pen and intaglio printing. Hence, the prepared nanocomposites signify an competent method towards long preservative fingerprints as well as great performance for data security operations. This work endorses a prospective paradigm for luminescence enhancement and its applications in advanced forensic science.

Novel aggregation induced emission based 7-(diethylamino)-3-(4-nitrophenyl)-2H-chromen-2-one for forensic and OLEDs applications

In this report, a novel solvatochromism, aggregation induced emission (AIE) based 7-(diethylamino)-3-(4-nitrophenyl)-2H-chromen-2-one fluorescent probe (CFP) was synthesizes via one-pot multi-component reaction system under ultrasonication method. The synthesized CFP was characterized using different instrumental techniques namely, Fourier transform infrared spectroscopy (FTIR), Proton nuclear magnetic resonance spectroscopy (1H NMR), Mass spectrometer, Scanning electron microscope (SEM), Energy dispersive X-ray analysis (EDAX), Thermal gravimetric analysis (TGA), Transmission electron microscopy (TEM), UV−Vis spectrometry and Fluorescence spectrophotometer. The synthesized CFP produces red emission in solid as well as in liquid state. The synthesized CFP was investigated as a new labeling mediator for the visualization of latent fingerprints (LFPs) on the different non-porous materials surface. The obtained CIE result proves that the organic moiety was extremely helpful for the fabrication of red-light emitting diodes in the display device. The synthesized CFP will play a crucial role in visualizing the LFPs on various materials surface, organic light emitting diodes (OLEDs) and anti-counterfeiting applications.

Highly Stable, Nondestructive, and Simple Visualization of Latent Blood Fingerprints Based on Covalent Bonding Between the Fluorescent Conjugated Polymer and Proteins in Blood.

Latent blood fingerprints (LBFPs) can provide critical information of foul play and help identify the suspects at violent crime scenes. The current methods for LBFP visualization are still not satisfactory because of the low sensitivity or complicated protocol. This study demonstrates a simple and effective LBFP visualization strategy by integrating a new amphiphilic fluorescent amino-functionalized conjugated polymer with the cotton-pad developing protocol. LBFPs on various substrates are visualized by simply covering them with the polymer solution-soaked cotton pads. The images display clear fingerprint patterns, ridge details, and sweat pores, even on very challenging substrates such as painted wood and multicolored can. The gray value analysis confirms semiquantitatively the enhancement of the contrast between ridges and furrows. Even LBFPs with various contaminations or aged for more than 600 days are effectively developed and visualized. The developed fingerprint images show superior stability over long storage time and against solvent washing. Moreover, the polymer causes no degradation of DNAs in the blood, suggesting the possibility of further DNA profiling and identification after development. The mechanistic investigation suggests that the formation of positive or inverted images can be attributed to the synergistic effects from the affinity between polymer and blood, and the affinity betwen polymer and substrate, as well as the slight quenching of polymer fluorescence by blood. Furthermore, the covalent bonding between the protonated primary amino group and proteins in blood endows the stability of the developed fingerprints. The result rationalizes the molecular design of the fluorescent polymer and sheds new light on the future strategies to effective LBFP visualization in practical applications.

Sensing and sensitive visualization of latent fingerprints on various surfaces using a versatile fluorescent aggregation-induced emission-based coumarin derivative.

The marked rise in criminal activity in society has made a difficult task for forensic scientists who aim to track any crime scene effectively, therefore visualization of latent fingerprints (LFPs) plays an increasingly vital role in forensics. In the present report, a highly sensitive solvatochromism, aggregation-induced emission-based 2-(4-nitrophenyl)-3H-benzocoumarin fluorescent dye (CFD) was fabricated using an ultrasonication protocol. The fluorescence properties of the CFD were analyzed using fluorescence spectrophotometer. The CFD produced a greenish yellow emission in solid and fluid states. An in-depth visualization of LFPs showed detailed ridge patterns under normal and ultraviolet light sources (254 and 365 nm) due to the excellent chemisorption of CFD onto the ridge patterns on the finger. All three types of ridge details were visualized without any background interference when using a simple and quick powder dusting method. Results revealed that, the present fluorescent dye can be used successfully for detection of latent fingerprints (LFPs) on various nonporous substrates surfaces, in organic light-emitting diodes applications (OLEDs), and for electrochemical sensing.

Ultrasound assisted Eu3+–doped strontium titanate nanophosphors: Labeling agent useful for visualization of latent fingerprints

We have established a controllable two–step strategy involving the ultrasound dispersion of the bulk solution to synthesize low–dimensional Eu3+–doped SrTiO3 (1–5 mol%) nanostructures. The crystal structure was carefully inspected by XRD which showed good agreement with a pure cubic phase, also indicating that the dopant's incorporation did not affect the crystalline structure. Photoluminescence emission spectra consists of characteristic red emissions owing to 5D0→7Fj (j= 0,1,2,3,4) transitions of Eu3+ ions. Morphological–behavior indicates that the grains were less agglomerated with a small average particle size of 45 nm. Finally, optimized nanoparticles were further utilized for the visualization of latent fingerprints on smooth surfaces. Visualized latent fingerprint exhibits high sensitivity, high contrast, and can obtain the complete ridge details. The results reveal that well–defined ridge characteristics were visualized under daylight and UV–light, demonstrating the material's efficacy in advanced–forensic investigations and the biometric–process of finger scanning.

Green emitting rare earth Gd2O3:Tb3+ nanoparticles for rapid imaging of latent fingerprint

A series of green emitting Gd2O3:Tb3+ (Tb: 0%–10% mol) nanoparticles (NP) were synthesized using the hydrothermal method, then characterized and evaluated for latent fingerprint visualization. X-ray diffraction study (XRD) revealed a cubic structure of the nanoparticles and the total incorporation of the terbium in the Gd2O3 matrix. Field Emission-Scanning Electron Microscopy (FESEM), Energy Dispersive x-ray Spectrometry (EDX) and Transmission Electron Microscopy (TEM) were used to study the morphology and the elementary composition of the NP. Photoluminescence (PL) studies showed strong green emission around 540 nm due to the transition 5D4 → 7F5. The luminescence color of the synthesized NP was characterized by the CIE 1931 chromaticity diagram. The potential use of the NP powders for the visualization of latent fingerprint under UV irradiation was assessed on various substrates. The latent fingerprint images revealed by the Gd2O3:Tb3+ NP powders are clear enough to extract and analyze reliable fingerprint features. The fingerprint quality was evaluated using three fingerprint quality assessment metrics and by extracting and measuring the visibility of the minutiae. The experimental results show very good quality images of the latent fingerprint acquired using the Gd2O3:Tb3+ NP and yield good minutiae extraction.

Detection of latent fingerprints using luminescent Gd0.95Eu0.05PO4 nanorods

Lanthanide ions doped luminescent materials are widely studied for latent fingerprint detection. However, most of these materials are synthesized at very high temperatures and use UV C light for visualization, which is harmful to eye, skin, etc. Herein, the Gd0.95Eu0.05PO4 nanorods synthesized by a simple co-precipitation method at 185 °C were reported for latent fingerprint visualization under 395 nm light. The Gd0.95Eu0.05PO4 nanomaterial has monoclinic crystal structure and shows rod-shaped morphology. Further, these Gd0.95Eu0.05PO4 nanorods exhibit excellent photoluminescence properties and strong fuchsia emission under UV light. These nanorods have been employed for developing latent fingerprints on various porous and non-porous substrates by the powder dusting technique, which exhibits clear and well defined details with high contrast, selectivity and sensitivity under 395 nm UV light. Latent fingerprints developed after 72 h of their deposition also show clear contrast with these nanorods. Therefore, the Gd0.95Eu0.05PO4 nanorods can be used for latent fingerprint visualization applications.

Coronene diimide-based 'bowl' nanostructures as red emitters for the analysis of latent fingerprints and metal ion detection.

We report an NIR-based photoluminescent material, namely benzo-coronene diimide (CDI 2), and its use in the visualization of latent fingerprints (LFPs) and in the metal ion detection in an aqueous medium. CDI 2 exhibited nano-sized interlinked fibre structures forming ‘bowl’ shaped nanoarchitectures as red emitters with the Commission Internationale de l'Eclairage (CIE) coordinates (x, y) of (0.67, 0.33) with 100% colour purity in the solid state. CDI 2 was confirmed to be the potential candidate for the analysis of LFPs and the detection of Pd2+/Cu2+ in an aqueous medium.

The selective deprotonation of carbon quantum dots for fluorescence detection of phosphate and visualization of latent fingerprints.

We developed a water-soluble, stable and selective "turn-on" fluorescence sensing platform based on carbon quantum dots (CQDs) for rapid determination of phosphate (Pi) in aqueous solutions and for visualization of latent fingerprints on paper. The hydroxyl groups on the surface of the synthesized CQDs can be deprotonated by Pi to trigger the intramolecular charge transfer (ICT) process and the inhibition of excited-state proton transfer (ESPT), achieving a turn-on emission response. CQDs demonstrated the capability to selectively detect Pi over other common ions and biomolecules with the linear fluorescence intensity change in the range from 0 to 100 μM. Moreover, the paper sprayed with the CQD solution showed a remarkable blue emission speckle and a fingerprint upon addition of Pi solution and finger touching, respectively. Notably, the fingerprint images including level 3 details (crossover, bifurcation, termination, and island and sweat pores) are also clearly identified and distinguished, indicating their potential application in document security. We believe that the as-synthesized CQDs will provide a new tool for Pi detection in aqueous media and paper document security.

Structural, optical and photoluminescence enhancement of 2-mercaptoacetic acid capped Mn2+ doped CdS nanoparticles and their applications in efficient detection of latent fingerprints

CdS:Mn2+ nanoparticles (NPs) stabilized with 2- mercaptoacetic acid (MAA) as a capping agent at different concentrations were developed by co-precipitation method. The X-ray diffraction (XRD) measurement revealed the existence of the cubic phase for stabilized NPs. Scherer’s method, Williamson-Hall (W-H) plot and size-strain plots (SSP) were helpful in the evaluation of the crystallite size and lattice strain of formed products. Ultraviolet–Visible absorption spectroscopy was adopted for energy gap determination, where Tauc’s plots infer that the energy gap increased with the increase in MAA volume percentage. The existence of MAA capping on CdS:Mn2+ was confirmed by fourier transform infrared (FTIR) spectroscopy. The outcome of transmission electron microscopy (TEM) results indicated the presence of spherical shape particles with a typical size of 6–7 nm, which is an encouraging feature for numerous applications. Two emission peaks around 477 nm (blue) and 575 nm (yellow) were observed for MAA stabilized CdS:Mn2+ NPs concerning photoluminescence (PL) spectroscopy. The disintegration and oxidation of the samples in the form of foremost weight loss and gain were studied by thermogravimetric analysis (TGA). Visualization of latent fingerprints (LFPs) under normal light on different porous and nonporous surfaces was conducted in the presence of MAA stabilized CdS:Mn2+ NPs. The acquired emissive fingerprint powder gave superior images with high distinction and resolution connecting the ridges and space. Based on these results, MAA capped Mn2+ doped CdS NPs can be used for the recognition of LFPs in solving criminal cases.

Ratiometric chemosensor for differentiation of TNP from other NACs using distinct blue fluorescence and visualization of latent fingerprints

Paper strips coated with the red-fluorescent probeDMAS-TPdisplay a distinct blue fluorescence with 2,4,6-trinitrophenol andSiO2@DMAS-TPNPs to visualize latent fingerprints up to level 3.