18 results about "Latent fingerprint" patented technology

The invention relates to a method for displaying latent fingerprints based on nanosecond laser preparation and oxide film transfer. Belongs to the field of latent fingerprint development. The method comprises the following steps that a transparent material is attached to metal, nanosecond laser penetrates through the transparent material and irradiates the surface of the metal through multi-line scanning, the metal is subjected to phase change, generated metal oxide molten particles are attached to the surface of the transparent material, and a compact metal oxide layer is formed. The oxide layer is arranged above the latent fingerprint, and after laser multi-line scanning, the oxide film and the transparent material interface form a high-voltage area. Through heat conduction, the oxide attached to the latent fingerprint is heated to be subjected to phase change, is driven by high pressure to be transferred to the surface of the fingerprint, is in contact with a latent fingerprint sample at a relatively low temperature and then deposits to push the molten mass to the surface of the latent fingerprint, and the molten mass deposits to form a film. But as skin secretions are attached to the ridge line, the deposition capacity of a molten mass is weak, the contrast ratio of the skin secretions and the molten mass is enhanced, and fingerprints appear. The method has the advantages of simplicity in operation, no pollution, low cost and the like. The method has potential application prospects in the criminal investigation field.

The invention discloses a wet latent fingerprint identification method and system based on a humidity self-adaptive optical storage device, a terminal and a medium, and the method comprises the steps: obtaining an original wet latent fingerprint image, and converting the original wet latent fingerprint image into an ultraviolet pulse sequence adaptive to the optical response characteristics of the humidity self-adaptive optical storage device; a reservoir array is built based on a humidity self-adaptive optical storage device, an ultraviolet light pulse sequence is received based on the reservoir array, and a current amplitude signal matched with a corresponding pixel fingerprint feature is output based on humidity adjustable and self-adaptive characteristics of the humidity self-adaptive optical storage device. Outputting a feature vector bearing the core feature of the wet latent fingerprint based on the current amplitude signal; and inputting the feature vector into a neural network for fingerprint identification, and outputting a fingerprint identification result based on a readout layer of the neural network. According to the invention, the core problems of low identification precision in a high-humidity environment, high delay of a traditional system and high energy consumption are effectively solved, and the efficiency and reliability of wet latent fingerprint identification are remarkably improved.

The invention relates to the technical field of forensic science criminal affairs, in particular to the field of special laboratory trace inspection, and more particularly relates to a reagent appearance fingerprint temperature control method applied to paper. A reagent appearing fingerprint temperature control method applied to paper is characterized by comprising the following steps that S1, an experiment is conducted in the same experiment environment; s2, taking indandione as a fingerprint appearing reagent, and dividing the fingerprint appearing reagent into a group A; ninhydrin is used as a fingerprint development reagent and is divided into a group B; s3, respectively carrying out the group A experiment and the group B experiment, gradually raising the temperature to carry out a fingerprint showing experiment in a short time when the experiment setting requirement is met, and judging the fingerprint showing effect, and recording the optimal baking temperature interval and the corresponding time; and S4, aiming at an experiment result, when a fingerprint display effect picture is obtained, performing standard photographing on the fingerprint, so that under a normal observation distance, pixel points cannot be distinguished by naked eyes, and potential fingerprints can be completely displayed and are regarded as clear and complete.

The application discloses a preparation method of biomass fluorescent carbon dot nanomaterials, which is prepared from natural plant ophiopogon japonicus leaves by a solvent thermal method to obtain fluorescent carbon quantum dots dispersed in a solution, and dried to obtain solid fluorescent powder. A fingerprint brush is used to take a small amount of fluorescent carbon dot nanomaterial powder to brush and develop latent fingerprints on different objects, and clear fingerprint detail features can be observed under ultraviolet light, and the method is suitable for fingerprint identification. The biomass fluorescent carbon dot nanomaterials are mainly prepared from natural plants, have simple preparation process, low manufacturing cost, convenient operation, environmental protection, non-toxicity, small harm to operators, good latent fingerprint development effect on different object surfaces, and are suitable for industrialized production and conventional fingerprint development work, and not only have a great driving effect on the development of fingerprint development technology, but also have great practical application value.

This invention discloses a method, system, terminal, and medium for wet latent fingerprint recognition based on a humidity-adaptive optical storage device. The method includes: acquiring an original wet latent fingerprint image; converting the original wet latent fingerprint image into an ultraviolet light pulse sequence adapted to the optical response characteristics of the humidity-adaptive optical storage device; constructing a reservoir array based on the humidity-adaptive optical storage device; receiving the ultraviolet light pulse sequence based on the reservoir array; outputting a current amplitude signal matching the fingerprint features of the corresponding pixel based on the humidity-adaptive optical storage device's adjustable and adaptive characteristics; and outputting a feature vector carrying the core features of the wet latent fingerprint based on the current amplitude signal; inputting the feature vector into a neural network for fingerprint recognition; and outputting the fingerprint recognition result based on the readout layer of the neural network. This invention effectively solves the core problems of low recognition accuracy, high latency, and high energy consumption in high humidity environments, significantly improving the efficiency and reliability of wet latent fingerprint recognition.

This invention discloses BODIPY dyes, their preparation methods, and their applications in latent fingerprint recognition. The invention prepares four BODIPY dyes with different structures and emission colors, all exhibiting high fluorescence quantum yields (over 55% absolute fluorescence quantum yield) and excellent lipophilicity. Using a spray method, latent fingerprints on different substrates can be efficiently and conveniently detected within 10 seconds. Furthermore, the detection solution demonstrates excellent stability, can be stored for up to 30 days, and achieves a color change from green to red through modulation. This modulation effectively addresses complex background colors, ensuring optimal latent fingerprint detection results under various color backgrounds.

This invention provides a protein-targeting bifunctional blue developing agent. Commercially available Prussian blue (Tianjin Zhonglian CAS: 14038-43-8) is used, with water as the solvent and benzalkonium chloride as the dispersant, and is ultrasonically dissolved to form a 4% (w / w) Prussian blue aqueous solution. It can be used to develop latent fingerprints or blood fingerprints containing grease on a sample using methods such as drop casting, spraying, and immersion. Under ambient light, the fingerprint turns blue under the action of the developing solution. This invention is applicable to most non-permeable samples and some semi-permeable samples. The dye formulation provided by this invention has low cost, simple preparation, rapid color development, easy operation, and is environmentally friendly. It can broaden new methods for fingerprint development in criminal investigations.

The invention provides a double-state emission fluorescent dye and a preparation method and application thereof in fingerprint development, the fluorescent dye comprises a triphenylamine group as an electron donor and a 2, 7-naphthyridine group as an electron acceptor, and the triphenylamine group and the 2, 7-naphthyridine group are connected through a pi conjugated structure. The fluorescent dye prepared by the invention has the characteristic of double-state emission, the preparation raw materials are easy to obtain, the process is simple and convenient, the prepared dye is good in stability, and specific structural design is carried out aiming at a fingerprint development application scene, so that the dye can be efficiently combined with finger secretions, the anti-interference capability is strong, and the fluorescent dye can be effectively applied to the field of latent fingerprint identification.

The invention discloses an N-arylindole AIE molecule as well as a preparation method and application thereof, and belongs to the field of organic small molecule photo-thermal materials. The problems that an existing organic fluorescent material is long in synthetic route, part of fluorescent molecules contain pyridine structural units, DNA information extraction in fingerprint remaining biological residues is interfered, fluorescence in an aggregation state is weak, DNA information extraction in fingerprint remaining biological residues is interfered, the biological residues easily cause chemical damage, feature integrity is affected, and the like are solved. And during imaging, background interference is easily caused, and high-contrast and high-resolution visualization of three-level features of the fingerprints is difficult to realize. The chemical general formula of the N-arylindole AIE molecule is shown in the specification. The preparation method comprises the following steps: mixing indole, a catalyst and an anhydrous organic solvent, then adding halogenated aromatic hydrocarbon or halogenated aryl nitrile, and continuously stirring; the invention is applied to latent fingerprint development, biological imaging, fluorescent probes or sensors.

The application discloses water-soluble organic fluorescent molecules, a preparation method thereof and application thereof in fingerprint detection, belongs to the field of criminal investigation science, and the obtained molecules all have good latent fingerprint developing effect. Three kinds of water-soluble organic fluorescent molecules prepared by the application have the structural formula: the molecules are designed into organic salts, the water solubility of the molecules is increased, the detection environment is more green, the TTC-1 and TTC-2 molecules both have the aggregation-induced emission (AIE) property, the light emission is stronger, and the latent fingerprint developing is more favorable. The fluorescent molecules have excellent light emission property, good solubility and fast enrichment speed of the fingerprint, and can be accurate to the tertiary structure of the fingerprint, the image of the fingerprint is clear, and the resolution is high.

The invention discloses a potential fingerprint display method based on graphite paper transfer and electrochemical luminescence, and belongs to the technical field of analytical chemistry, forensic medicine and potential fingerprint display. According to the method, luminescent molecules and a co-reactant react in the area, not covered by fingerprints, of the surface of a graphite paper working electrode to generate electrochemical luminescence, so that high-contrast fingerprint lines are displayed, and the first-level to third-level structures of the fingerprints can be clearly observed. According to the method, potential fingerprints on the surface of a porous permeable object are shown by using an electrochemical luminescence technology. Meanwhile, the graphite paper has good adsorption capacity on fingerprint residues, so that the method can be used for extracting and imaging potential fingerprints on the surfaces of various objects. The method combines a near-zero background electrochemiluminescence imaging technology and a flexible graphite paper transfer material, the operation process is simple and convenient, and imaging is rapid. In addition, the method can avoid display effect inconsistency caused by significant difference of personal sweat secretions, and is superior to methods such as physical developing agents and the like.

This invention discloses a fingerprint development reagent based on natural AIE compounds and precipitated silica, its preparation method, and its application, belonging to the field of forensic identification technology. The reagent is a particulate suspension comprising precipitated silica, natural AIE compounds, a surfactant, and a solvent. During preparation, the surfactant is dissolved in the solvent, the natural AIE compound is added and dissolved, and then precipitated silica is added in batches with stirring to obtain a uniform and stable suspension. This invention uses naturally derived AIE active substances, which are non-toxic, environmentally friendly, and low-cost, avoiding the biotoxicity and complex preparation process of traditional synthetic dyes. It also effectively solves the problems of dust pollution and poor compatibility with moist objects in powder development methods. It achieves high-contrast, high-definition fluorescence development of latent fingerprints on both dry and moist, non-permeable surfaces. The preparation process is simple and controllable, easy to scale up, and has good application prospects in rapid on-site detection fields such as criminal investigation and forensic identification.

The invention discloses an organic fluorescent material with AIE performance and a preparation method and application thereof, and belongs to the technical field of AIE materials.The AIE material with water solubility is prepared by modifying the structure of AIE micromolecules, latent fingerprint development under a soaking method can be achieved by means of the AIE performance, and the AIE performance is improved. Due to the water solubility, the aqueous solution of the material can be developed by using an ultrasonic atomizer through a spraying method; in addition, a layered double hydroxide (LDHs) loading strategy is utilized, aggregation of AIE molecules on a solid-phase interface is promoted through electrostatic interaction, and effective development of porous material fingerprints through a powder method is achieved; the organic fluorescent material with AIE performance prepared by the invention can realize optimal latent fingerprint detection in different scenes by using a soaking method, a spraying method and a powder spraying method.

The invention relates to the technical field of organic materials, and particularly discloses an organic compound with an aggregation-induced emission effect and a preparation method and application thereof. The novel boron difluoride compound with the aggregation-induced emission characteristic is synthesized, when the novel boron difluoride compound is used as a latent fingerprint developing agent, all three levels of fingerprint feature details can be shown through the hydrophobic interaction between the compound and oleic acid secreted by sweat, and therefore the latent fingerprint developing agent can be used for developing the latent fingerprint developing agent. The stability, old fingerprint extraction capability and hydrophobicity of the compounds lay a foundation for potential application of the compounds in the fields of forensic chemistry and criminal investigation, and the problem that in the prior art, an imaging mechanism between the boron difluoride compound and the LFPs is not clear is effectively solved.

This invention provides an organic conjugated polymer fluorescent material for developing latent fingerprints in blood, its preparation method, and its applications, relating to the field of conjugated polymer technology. The structural formula of the organic conjugated polymer of this invention is as follows: wherein Ar is or R1 is H, a C1-C16 alkyl group, a C1-C16 alkoxy group, or a C1-C16 alkylthiol group; R2 is H or a C1-C16 alkyl group; x is 0 or 0.01; and n is a natural number from 1 to 300. The polymer of this invention exhibits high sensitivity, superior development performance, and strong anti-interference capabilities.

The invention provides a latent fingerprint developing method which comprises the following steps: (1) preparing a deep-eutectic solvent: adding choline chloride into ethylene glycol, heating and stirring to obtain the deep-eutectic solvent; (2) a plating solution is prepared, specifically, copper salt is taken and added into the eutectic solvent to be stirred and dissolved, then a complexing agent is added, stirring continues to be conducted, and the plating solution is obtained; (3) copper immersion plating: immersing the latent fingerprint object into a plating solution for deposition reaction; and (4) drying: washing and drying the latent fingerprint object after the deposition reaction, so that clear fingerprints can be directly observed under natural light. The method is simple and easy to operate, the showing effect is good, fingerprints are clear and visible, the characteristics are obvious, the integrity is good, and the plating solution is simple in component, environmentally friendly and low in cost.

The invention provides a modified ferroferric oxide material as well as a preparation method and application thereof. The modified ferroferric oxide material comprises a specific structure of a ferroferric oxide core, a polydopamine layer and a carbon layer, the ferroferric oxide core has a specific specific surface area, the polydopamine layer and the carbon layer comprise hydroxyl and carbon-carbon double bonds, and the modified ferroferric oxide material has specific porosity, pore diameter and specific surface area. When being applied to on-site trace inspection, the device is high in adsorption capacity, and can detect latent fingerprints which are left for as long as 45 days; the application object range is wide, and the method is suitable for traces on semi-permeable and permeable surfaces of wood boards, aluminum foils and the like and traces on the surfaces of adhesive objects such as adhesive tapes and the like; the modified ferroferric oxide material is high in stability and can still be normally used after being stored for 60 days; in addition, the method has the advantages of low biotoxicity, recyclability and the like.