Method for showing potential fingerprint traces

Abstract

The invention discloses a method for showing a potential fingerprint trace. The method for showing the potential fingerprint mark comprises the following steps of: aligning a mist outlet of an atomizer filled with a rhodamine 6G solution to an object with the potential fingerprint mark for atomizing, and exciting by using a light source to generate fluorescence after the atomization is finished. According to the showing method, the rhodamine 6G solution is atomized into fog drops through the atomization technology, the fog drops are adsorbed on fingerprint streakline substances, contrast is generated, showing of potential fingerprint traces can be directly achieved, extra reagents and conditions are not needed, operation is easy, the needed showing time can be greatly shortened, and the method is suitable for popularization and application. And meanwhile, the method is suitable for non-permeable objects, permeable objects and semi-permeable objects.

Description

Technical Field

[0001] The invention relates to a method for revealing latent fingerprint traces, belonging to the field of fingerprint revealing in forensic science. Background Art

[0002] Fingerprint inspection technology is one of the key technologies for biological individual identification. Fingerprints left at the crime scene are often latent and cannot be identified by the naked eye. Physical, chemical or biological methods are needed to reveal the fingerprints. The fingerprints at the crime scene include latent fingerprints on non-permeable, semi-permeable, and permeable objects. This also determines the diversity of methods for revealing latent fingerprints. At present, powder brushing, "502" glue, vacuum coating and other methods are usually selected for fingerprints on non-permeable objects. Ninhydrin, DFO and indole are usually selected for latent fingerprints on permeable objects. Among the conventional revealing methods currently used, each method is limited to one type of object and requires special equipment and a certain amount of operation time. In particular, the discovery and extraction of fingerprints during on-site investigations are subject to certain restrictions.

[0003] "502" glue is a colorless liquid that is volatile and easy to polymerize into a solid. It is a commonly used adhesive, and its main component is ethyl α-cyanoacrylate. Since ethyl α-cyanoacrylate has strong electron-withdrawing groups - cyano and ester groups, it can be induced to polymerize under the initiation of trace amounts of water, weak bases and other anions to form solid polymers, thereby revealing fingerprints. Rhodamine 6G, as a fluorescent dye, has good fluorescence quantum yield and light stability. It is usually used as a laser medium and fluorescent tracer and is widely used in cosmetics, food, textiles and pharmaceutical processes. In the field of fingerprint visualization, since Rhodamine 6G can be adsorbed on the fingerprint lines after 502 glue fumigation, the fingerprints after "502" fumigation are usually smeared and rinsed with Rhodamine 6G solution to achieve dyeing treatment, which can solve the problem of weak contrast of fingerprints on light-colored non-permeable objects after 502 glue visualization to a certain extent, and can improve the contrast. However, the application of Rhodamine 6G in the field of fingerprint visualization is limited to this. It undoubtedly still relies on the adsorption between α-cyanoacrylate and fingerprint residues after polymerization. The "502" glue fumigation fingerprint is usually carried out in a relatively closed space by heating and volatilizing the air to fill with α-cyanoacrylate monomers. The operation is relatively cumbersome. In addition, the current "502" glue + Rhodamine 6G visualization method is mainly used for non-permeable light-colored objects, and "502" glue is more likely to undergo polymerization on material objects with smooth surfaces and linear structures. It also has a certain visualization effect on sweat latent fingerprints on some semi-permeable objects, but the effect is limited. More importantly, this method cannot be applied to permeable objects. After the "502" glue is revealed, although it can be enhanced by applying and rinsing with Rhodamine 6G solution to achieve the effect of increasing contrast, the operation is also cumbersome and there is a risk of damaging the fingerprint again. Therefore, directly utilizing the fluorescence properties of Rhodamine 6G to develop a relatively safe, easy-to-operate, and applicable method for revealing fingerprints on a variety of objects remains a technical problem that needs to be solved urgently. Summary of the invention

[0004] The purpose of the present invention is to provide a method for revealing latent fingerprint traces. The method can directly realize the revealing of latent fingerprint traces by atomizing a rhodamine 6G solution into droplets using atomization technology and interacting with the fingerprint of an object. No additional reagents and conditions are required, the operation is simple, and the required revealing time can be greatly shortened. The method is also applicable to non-permeable objects, permeable objects and semi-permeable objects.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention provides a method for revealing latent fingerprint traces, comprising the following steps:

[0007] Aim the atomizer outlet containing Rhodamine 6G solution at the object with potential fingerprints to atomize, and after atomization, use a light source to excite to produce fluorescence.

[0008] In the above method for revealing latent fingerprints, the solvent of the Rhodamine 6G solution is an organic solvent, preferably anhydrous ethanol or anhydrous methanol.

[0009] In the above method for revealing latent fingerprints, the concentration of the Rhodamine 6G solution is 0.25-5 g / L.

[0010] In the above method for revealing latent fingerprint traces, the atomizer includes any one of an ultrasonic atomizer, a compression atomizer, and a mesh atomizer;

[0011] The specifications of the atomizer are as follows: the diameter of the droplets is 1 to 100 μm; as an example, the proportion of droplets with a diameter of ≤5 μm is greater than 60%, and the median diameter of the mist particles is 5 μm±25%.

[0012] In the above method for revealing latent fingerprint traces, the spray rate of the atomizer is ≥ 0.2 mL / min;

[0013] In the atomization step, the distance between the atomization outlet and the object is 3 cm to 10 cm, and the atomization time is 3 s to 20 s.

[0014] In the above method for revealing latent fingerprint traces, the object is any one of an impermeable object, a permeable object and a semi-permeable object.

[0015] In the above method for revealing latent fingerprint traces, the atomization is carried out in an environment with a temperature of 5 to 40° C. and a relative humidity of less than 80%.

[0016] In the above method for revealing latent fingerprint traces, the wavelength of the light source is 530nm.

[0017] In the above method for visualizing latent fingerprints, the fingerprints are visualized under a 571 nm filter.

[0018] In the above method for revealing latent fingerprint traces, the fingerprint is a finger print or a palm print.

[0019] Due to the application of the above technical solution, the present invention has the following advantages compared with the existing display technology:

[0020] (1) In the development method of the present invention, rhodamine 6G is used as the material component of the development reagent, and anhydrous ethanol is selected as the dissolving reagent of the development reagent. The components are few in number, the solvent properties are stable, the preparation is simple, and it is safe and environmentally friendly.

[0021] (2) Atomization technology is to turn the reagent into fine droplets. The principle is to use high-frequency electronic oscillation and high-frequency resonance of the atomizer to break up the liquid molecular structure or pass the solution through a metal mesh to produce a natural and elegant mist, without heating or adding any chemical reagents. The visualization method of the present invention uses atomization technology to atomize the rhodamine 6G solution into droplets, which interact with the object fingerprint. The fingerprint traces can be directly visualized at room temperature without the need for additional reagents and conditions. The operation is simple and the required visualization time can be greatly shortened.

[0022] (3) The visualization method of the present invention is applicable to non-permeable objects, permeable objects, and semi-permeable objects at the same time, and has strong fluorescence brightness and good visualization effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The results of different operation methods of Rhodamine 6G in Example 1 of the present invention for revealing sweat latent fingerprints on a plastic bag are shown, namely, micro-grid atomization method (A), spray method (B), drop method (C), and immersion method (D).

[0024] Figure 2 These are the visualization effects of sweat latent fingerprints using the visualization methods of 502 glue fumigation + rhodamine 6G staining (A) and rhodamine 6G micro-mesh atomization technology (B) in Example 2 of the present invention.

[0025] Figure 3 This is a diagram showing the effect of revealing sweat latent fingerprints using different dye spray methods in Example 3 of the present invention.

[0026] Figure 4 These are the effects of Rhodamine 6G in different solvents on LFP on plastic bags in Example 4 of the present invention, wherein the solvents are ethanol (A), methanol (B), petroleum ether (C) and ethyl acetate (D).

[0027] Figure 5 This is a diagram showing the effect of latent fingerprints on stainless steel in Example 5 of the present invention.

[0028] Figure 6 This is a diagram showing the effect of latent fingerprints on plastic in Example 6 of the present invention.

[0029] Figure 7 This is a diagram showing the effect of latent fingerprints on A4 paper in Example 7 of the present invention.

[0030] Figure 8 This is a diagram showing the effect of latent fingerprints of sweat on hard cardboard in Example 8 of the present invention.

[0031] Fig. 9 This is a diagram showing the effect of latent fingerprints on leather in Example 9 of the present invention. DETAILED DESCRIPTION

[0032] As described in the background art, Rhodamine 6G is a fluorescent dye. When displaying fingerprints, it is usually dyed after the "502" smoked fingerprints to solve the problem of weak contrast after the fingerprints on the light-colored object are developed by 502 glue. This is because when the finger touches the object, the secreted substances on the fingerprint will be transferred to the surface of the object, forming a latent fingerprint that is invisible to the naked eye. The vapor volatilized by cyanoacrylate can undergo polymerization reaction on the fingerprint to generate a white polymer, so that the invisible fingerprint traces left on the surface of the object are revealed. The ethyl cyanoacrylate polymer has a three-dimensional porous structure, and the dye molecules are easily captured and adsorbed by the polymer. The optical properties of the dye can increase the contrast between the fingerprint and the background, thereby achieving the purpose of enhancing the fingerprint. It can be seen that the display effect of Rhodamine 6G on the fingerprint traces in the prior art depends on the adsorption of the dye by the ethyl cyanoacrylate polymer itself. The current "502" glue + Rhodamine 6G dyeing display method is cumbersome to operate and has limited applicable objects. To this end, the inventor accidentally discovered in the course of practice that the use of rhodamine 6G alone to atomize and visualize fingerprints can directly visualize fingerprints by exciting fluorescence, and has a wide range of applicability.

[0033] Based on this, the present invention provides a method for revealing latent fingerprint traces, comprising the following steps: aiming the mist outlet of an atomizer filled with rhodamine 6G solution at an object of latent fingerprint traces for atomization, and after atomization, exciting with a light source to generate fluorescence.

[0034] Regarding the processing method and dye type, in the embodiments of the present invention, the inventors compared the display effects of different operation methods such as drop development method, immersion method, spray method, micro-grid atomization method and dyes such as rhodamine 6G, amino black 10B, methyl violet and acid yellow on handprint traces. The results showed that only by using rhodamine 6G and micro-grid atomization method can the color of handprint traces be realized, and the color development effect is equivalent to the effect of "502" glue fumigation + rhodamine 6G dyeing treatment, and there is no background interference. This may be because the atomization technology can change the liquid rhodamine 6G solution into a fine mist, and the fine mist rhodamine 6G solution can be evenly adsorbed on the handprint line material, and then can excite fluorescence.

[0035] Regarding the choice of solvent, in practice, the inventors have tried different types of solvents for Rhodamine 6G. In the embodiments of the present invention, the inventors compared the development effects of different organic solvents such as ethanol, methanol, petroleum ether and ethyl acetate. The results showed that ethanol or methanol was the best solvent for development. Therefore, in the method of the present invention, the solvent of Rhodamine 6G is an organic solvent, preferably anhydrous ethanol or anhydrous methanol. Considering the hazards to the experimenters and the environment, the present invention further investigates the development of different objects with ethanol as the solvent. In an optional embodiment, the concentration of the Rhodamine 6G solution is 0.25-5 g / L, such as 0.5 g / L.

[0036] According to the present invention, unlike the spraying method of a spray pot (the diameter of the droplets is about several hundred microns or even larger), the atomizer can atomize the solution into micron-sized aerosol particles. In the present invention, the atomizer includes any one of an ultrasonic atomizer, a compression atomizer and a mesh atomizer. As an example, the atomizer is a mesh atomizer, and the mesh atomizer can be a device that arbitrarily utilizes high-frequency resonant oscillation to atomize the solution through a mesh into micron-sized particles. Optionally, it can be driven by a certain frequency oscillation of the circuit to make the piezoelectric ceramic transducer resonate and oscillate, thereby driving the metal mesh to oscillate at high speed, so that the solution passes through many tiny mesh holes on the metal mesh and is quickly ejected to form countless tiny atomized particles. Preferably, the specifications of the atomizer are as follows: the droplet diameter is 1 to 100 μm. As an example, the proportion of droplets with a diameter of ≤5 μm is >60%, and the median diameter of the mist particles is 5 μm ± 25%. Among them, the median particle size of the mist particles is measured with 0.9% physiological saline at a temperature of 25±3°C and a humidity of 60%±15%RH. The equivalent volume particle size distribution curve of the mist particles measured under this condition is used to obtain the proportion of droplets with a diameter of ≤5μm. When in use, the mist outlet of the nebulizer is aimed at the object with potential fingerprints for atomization, and the spray rate is ≥0.2mL / min (such as 0.2mL / min). During atomization, the fingerprint material is fully contacted with the atomization agent, which can usually be completed within 3s to 20s (such as 3 seconds). The distance between the mist outlet and the object can be appropriately adjusted within 3cm to 10cm, such as 3cm to 5cm, 3cm or 5cm. Optionally, the nebulizer is a medical nebulizer, such as a mesh nebulizer (micro-mesh nebulizer) with an oscillation frequency of 120KHz±10%. In the embodiment of the present invention, the atomizer is a micro-mesh atomizer YS34E of Kangheng Medical. When in use, the atomizer outlet is aimed at the object with potential fingerprint traces, and the atomizer is started for atomization.

[0037] According to the present invention, in the present invention, the object can be any one of an impermeable object, a permeable object, and a semi-permeable object. According to the definition in "GA / T144-2018 Forensic Science Fingerprint Professional Terminology", the object itself is distinguished according to its ability to absorb liquid. Among them, the impermeable object includes but is not limited to stainless steel, plastic and other objects that do not absorb liquid, the semi-permeable object includes but is not limited to leather, hard cardboard and other media that are permeable between the two objects; the permeable object includes but is not limited to A4 paper and other objects that can quickly absorb liquid.

[0038] According to the present invention, the atomization is carried out in an environment with a temperature of 5 to 40°C and a relative humidity of less than 80%. In the present invention, the term "relative humidity" is represented by RH (Relative Humidity), which refers to the ratio of the actual water vapor pressure in the air to the saturated water vapor pressure at the current temperature. It reflects the degree of air away from saturated air and represents the ratio of the absolute humidity in the air to the saturated absolute humidity at the same temperature and pressure. It is a percentage value, that is, it refers to the mass ratio of water vapor contained in a certain wet air to the mass ratio of water vapor contained in saturated air at the same temperature and pressure. During the operation, those skilled in the art can determine it according to the environment (geographic location, season) in which the experiment is located. For example, in the embodiment of the present invention, the temperature is 24°C and the relative humidity is 30%, but the present invention is by no means limited to this. As long as the appropriate conditions are met, the atomized reagent can be adsorbed on the grain line.

[0039] According to the present invention, the wavelength of the light source is determined according to the fluorescence excitation wavelength of rhodamine, such as 530nm. The handprint trace can be specifically displayed under a filter, and the filter can be determined according to the fluorescence color, such as using a 571nm filter to observe the handprint trace. The handprint can be a finger print or a palm print.

[0040] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0041] The methods used in the following examples, unless otherwise specified, are all conventional methods, carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial sources.

[0042] The sources of the materials in the following examples are as follows:

[0043] Rhodamine 6G (AR, 95%, MW: 479.01, C 28 H 31 N 2 O 3 Cl), Aladdin;

[0044] Ethanol (absolute ethanol) (analytical grade, AR, C 2 H 6 O, FW46.07), Shanghai test.

[0045] The sources of the instruments in the following embodiments are as follows:

[0046] Nebulizer (YS34E Kangheng Medical), the median diameter of the mist particles is 5μm±25%, the spray rate is ≥0.2mL / min, and the operating frequency is 120KHz±10%.

[0047] The photographing and observation equipment was DCS-4 (Foster & Freeman, Ltd).

[0048] Example 1: Comparison of different treatment methods for latent handprints on white plastic bags

[0049] With anhydrous ethanol as solvent, 0.5g / L rhodamine 6G solution was prepared as a developing agent. With a white plastic bag as the object, according to the simulated on-site environment, volunteers' hands were not treated in any way, and handprints (fingerprints) were directly pressed under natural conditions and left for 5 hours at a temperature of 24°C and a relative humidity of 30%.

[0050] The "four-point method" was used to compare the display effects of four operating methods (drip method, immersion method, spray method, and micro-mesh atomization method) on white plastic bags.

[0051] The immersion method refers to directly immersing the sample in the solution of the developing reagent for 1-3 minutes;

[0052] The drop developing method involves using a rubber-tipped dropper to place one or two drops of solution on areas where fingerprints may be present, and using absorbent paper to remove excess developing solution from the edge of the object;

[0053] The spray method refers to using a spray bottle to spray the developing reagent in atomized form on the surface of the trace-bearing object;

[0054] The microgrid atomization method refers to the use of micro-voltage braking to generate pressure-free, low-flow micron-sized Rhodamine 6G droplets to the surface of the object, that is, the mist outlet of the atomizer containing Rhodamine 6G solution is aimed at the surface of the object for atomization, the distance between the mist outlet and the object is 3 cm, and the atomization time is 3 s.

[0055] When there is obvious stain residue on the surface of the object, it needs to be rinsed with distilled water. After the operation is completed, place it in the handprint enhancement DCS-4 system, adjust the camera and excitation light source parameters, and shoot and fix it through the 571nm filter under the excitation of the 530nm light source. The specific effect is as follows Figure 1 As shown. Figure 1 It can be seen that the fingerprint lines displayed by the micro-mesh atomization method are the clearest, with strong fluorescent brightness and good display effect.

[0056] Example 2: Comparison of 502 glue fumigation + rhodamine 6G dyeing and rhodamine 6G atomization

[0057] With anhydrous ethanol as solvent, 0.5g / L rhodamine 6G solution was prepared as a developing agent. With a white plastic bag as the object, according to the simulated on-site environment, volunteers' hands were not treated in any way, and handprints (fingerprints) were directly pressed under natural conditions and left for 5 hours at a temperature of 24°C and a relative humidity of 30%.

[0058] Rhodamine 6G microgrid atomization ( Figure 2 B) The operation is as follows: the mist outlet of the atomizer containing the Rhodamine 6G solution is directed toward the surface of the object for atomization, the distance between the mist outlet and the object is 3 cm, after atomization for 3 seconds, it is excited with a 530 nm light source and observed with a 571 nm filter.

[0059] 502 fumigation method + rhodamine 6G staining ( Figure 2 The operation of A) is as follows: after the 502 fumigation, use a cotton ball with rhodamine 6G solution to smear it on the surface of the handprint object, and finally rinse it with running distilled water and dry it.

[0060] The experimental results are compared as Figure 2 As shown. Figure 2 It can be seen that the fingerprints after 502 glue fumigation can be further enhanced by Rhodamine 6G, but the background has traces of smearing, which has a certain impact on the visualization effect. It was unexpectedly discovered that fingerprints can be visualized by direct atomization of Rhodamine 6G, and the visualization effect is good, which is equivalent to the visualization effect of 502 fumigation method + Rhodamine 6G staining treatment, or even better than the former.

[0061] Example 3: Comparison of the appearance of different dyes

[0062] Rhodamine 6G (excitation with 530nm light source, observation with 571nm filter): Use anhydrous ethanol as solvent to prepare 0.5g / L Rhodamine 6G solution.

[0063] Amido black 10B (no fluorescence when observed with the naked eye): Use anhydrous ethanol as solvent to prepare 0.6 g / L Amido black 10B solution, and follow the same steps as above.

[0064] Methyl violet (observed with the naked eye, no fluorescence): Use anhydrous ethanol as solvent to prepare 0.4 g / L methyl violet solution, and the subsequent steps are the same as above.

[0065] Acid yellow (excitation with 440mm light source, observation with 529mm filter): Use anhydrous ethanol as solvent to prepare 0.4g / L acid yellow solution. The subsequent operation steps are the same as above.

[0066] Using a white plastic bag as the object, according to the simulated on-site environment, volunteers did not do any treatment on their hands, and directly pressed their handprints (fingerprints) under natural conditions and left them for 5 hours at a temperature of 24°C and a relative humidity of 30%. Then, spray bottles containing the above dye solutions were aimed at the surface of the object for atomization. After atomization for 3 seconds, natural light and fluorescence of different bands were used for observation. The comparison results are shown in the figure. Figure 3 shown.

[0067] Depend on Figure 3 It can be seen that, unexpectedly, fingerprints can be revealed by direct spraying only when the dye is Rhodamine 6G.

[0068] Example 4: Comparison of the appearance of Rhodamine 6G solutions in different solvents

[0069] In order to explore the effect of different solvents on the visualization effect of Rhodamine 6G, ethanol, methanol, petroleum ether and ethyl acetate were used as solvents to prepare 0.5g / L Rhodamine 6G solution. The "four-point method" experiment was used to compare and explore the visualization effect of the above four solvent formulas on the fingerprints on the surface of plastic bags. The specific steps are as follows:

[0070] Taking plastic bags as the object, according to the simulated on-site environment, volunteers' hands were not treated in any way and directly printed handprints (fingerprints) under natural conditions and left for 5 hours at a temperature of 24°C and a relative humidity of 30%. Then, the mist outlet of the nebulizer containing the Rhodamine 6G solution in the above-mentioned different solvents was aimed at the surface of the object for atomization. The distance between the mist outlet and the object was 3 cm. After atomization for 3 seconds, it was excited with a 530nm light source and observed with a 571nm filter.

[0071] The effect is as follows Figure 4 (A: ethanol, B: methanol, C: petroleum ether, D: ethyl acetate). The results show that the four different solvents all give good results in the process of fingerprint visualization on the surface of plastic bags, and the formula with ethanol or methanol as solvent has the best effect. A comprehensive analysis of the effects of the four solvents on the visualization of fingerprints on the surface of the trace-bearing object shows that ethanol is relatively less toxic and less harmful to the experimenters and the environment during the fingerprint visualization process, and finally anhydrous ethanol is determined to be the best solvent.

[0072] Example 5: Display of latent fingerprints on stainless steel

[0073] With anhydrous ethanol as solvent, 0.5g / L Rhodamine 6G solution was prepared. With ordinary stainless steel as the object, according to the simulated on-site environment, volunteers did not do any treatment on their hands, and directly pressed handprints (fingerprints) under natural conditions, and left them for 5 hours at a temperature of 24°C and a relative humidity of 30%. Then, the mist outlet of the atomizer containing the Rhodamine 6G solution was aimed at the surface of the object for atomization. The distance between the mist outlet and the object was 5cm. After atomization for 3s, it was immediately excited with a 530nm light source and observed with a 571nm filter, and fluorescent handprints could be seen. After taking pictures and observation, the results are as follows Figure 5 shown.

[0074] Example 6: Display of latent fingerprints on plastic

[0075] With anhydrous ethanol as solvent, 0.5g / L Rhodamine 6G solution was prepared. With ordinary plastic bottles as objects, according to the simulated on-site environment, volunteers did not do any treatment on their hands, and directly pressed handprints (fingerprints) under natural conditions, and left them for 5 hours at a temperature of 24°C and a relative humidity of 30%. Then, the atomizer containing the Rhodamine 6G solution was aimed at the surface of the object for atomization, and the distance between the mist outlet and the object was 5cm. After atomization for 3s, it was immediately excited with a 530nm light source and observed with a 571nm filter, and fluorescent handprints could be seen. After taking pictures and observing, the results are as follows Figure 6 shown.

[0076] Example 7: Display of latent handprints on A4 paper

[0077] With anhydrous ethanol as solvent, 0.5g / L Rhodamine 6G solution was prepared. With ordinary A4 paper as the object, according to the simulated on-site environment, volunteers did not do any treatment on their hands, and directly pressed handprints (fingerprints) under natural conditions, and left them for 5 hours at a temperature of 24°C and a relative humidity of 30%. Then, the mist outlet of the atomizer containing the Rhodamine 6G solution was aimed at the surface of the object for atomization. The distance between the mist outlet and the object was 3cm. After atomization for 10s, it was immediately excited with a 530nm light source and observed with a 571nm filter, and fluorescent handprints could be seen. After taking pictures and observation, the results are as follows Figure 7 shown.

[0078] Example 8: Display of latent fingerprints on cardboard

[0079] With anhydrous ethanol as solvent, 0.5g / L Rhodamine 6G solution was prepared. With white cardboard as the object, according to the simulated on-site environment, volunteers did not do any treatment on their hands, and directly pressed handprints (fingerprints) under natural conditions, and left them for 5 hours at a temperature of 24°C and a relative humidity of 30%. Then, the mist outlet of the atomizer containing the Rhodamine 6G solution was aimed at the surface of the object for atomization. The distance between the mist outlet and the object was 3cm. After atomization for 10s, it was immediately excited with a 530nm light source and observed with a 571nm filter, and fluorescent handprints could be seen. After taking pictures and observation, the results are as follows Figure 8 shown.

[0080] Example 9: Display of latent fingerprints on leather

[0081] With anhydrous ethanol as solvent, 0.5g / L Rhodamine 6G solution was prepared. With ordinary black leather as the object, according to the simulated on-site environment, volunteers did not make any treatment on their hands, and directly pressed handprints (fingerprints) under natural conditions, and left them for 5 hours at a temperature of 24°C and a relative humidity of 30%. Then, the mist outlet of the atomizer containing the Rhodamine 6G solution was aimed at the surface of the object for atomization. The distance between the mist outlet and the object was 3cm. After atomization for 10s, it was immediately excited with a 530nm light source and observed with a 571nm filter, and fluorescent handprints could be seen. After taking pictures and observation, the results are as follows Fig. 9 shown.

[0082] It can be seen from Examples 5 to 9 that the visualization method of the present invention is applicable to non-permeable objects, permeable objects, and semi-permeable objects.

[0083] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, can implement the present invention in a wider range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that the present invention can be further improved. In a word, according to the principle of the present invention, the application is intended to include any changes, uses or improvements to the present invention, including departing from the disclosed scope in the application and the changes made with conventional techniques known in the art.

Claims

1. A method for revealing latent fingerprint traces, characterized in that: The steps include: Aim the atomizer outlet containing Rhodamine 6G solution at the object with potential fingerprints to atomize, and after atomization, use a light source to excite to produce fluorescence.

2. The method for revealing latent fingerprint traces according to claim 1, characterized in that: The solvent of the Rhodamine 6G solution is an organic solvent, preferably anhydrous ethanol or anhydrous methanol.

3. The method for revealing latent fingerprint traces according to any one of claims 1-2, characterized in that: The concentration of the rhodamine 6G solution is 0.25-5 g / L.

4. The method for revealing latent fingerprint traces according to any one of claims 1 to 3, characterized in that: The nebulizer includes any one of an ultrasonic nebulizer, a compression nebulizer and a mesh nebulizer; The specifications of the atomizer are as follows: the diameter of the droplets is 1 to 100 μm; preferably, the proportion of droplets with a diameter of ≤5 μm is greater than 60%, and the median diameter of the mist particles is 5 μm±25%.

5. The method for revealing latent fingerprint traces according to any one of claims 1 to 4, characterized in that: The spray rate of the nebulizer is ≥ 0.2 mL / min; In the atomization step, the distance between the atomization outlet and the object is 3 cm to 10 cm, and the atomization time is 3 s to 20 s.

6. The method for revealing latent fingerprint traces according to any one of claims 1 to 5, characterized in that: The guest is any one of an impermeable guest, a permeable guest, and a semi-permeable guest.

7. The method for revealing latent fingerprint traces according to any one of claims 1 to 6, characterized in that: The atomization is carried out in an environment with a temperature of 5-40° C. and a relative humidity of less than 80%.

8. The method for revealing latent fingerprint traces according to any one of claims 1 to 7, characterized in that: The wavelength of the light source is 530 nm.

9. The method for revealing latent fingerprint traces according to any one of claims 1 to 8, characterized in that: The fingerprints were visualized under a 571 nm filter.

10. The method for revealing latent fingerprint traces according to any one of claims 1 to 9, characterized in that: The handprint is a finger print or a palm print.

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