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A method for displaying latent fingerprints on the surface of different hydrophilic and hydrophobic materials

A water-based material and latent fingerprint technology, which is applied in the field of fingerprint identification, can solve the problems of inapplicable latent fingerprint display and popularization and application of methods, unsatisfactory secondary structure display effect, and lack of latent fingerprint display ability, so as to achieve fast and easy display. Popularization, excellent effect

Inactive Publication Date: 2018-01-16
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional display method has the following disadvantages: reagents and other items are harmful to the operator's body; the display effect is not obvious enough, generally only the primary structure of the fingerprint can be displayed, and the secondary structure display effect is not ideal; it has certain damage to the latent fingerprint. It is not capable of displaying latent fingerprints on some difficult objects; it can only display a single image of positive or negative images
However, these fingerprint display technologies usually require expensive precision instruments and special skill training, and are not suitable for the popular application of latent fingerprint display and methods at crime scenes

Method used

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  • A method for displaying latent fingerprints on the surface of different hydrophilic and hydrophobic materials
  • A method for displaying latent fingerprints on the surface of different hydrophilic and hydrophobic materials
  • A method for displaying latent fingerprints on the surface of different hydrophilic and hydrophobic materials

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Taking the appearance of latent fingerprints on the surface of PVDF film as an example, the specific operation has the following steps:

[0024] (1) Cut the PVDF membrane with scissors into a size of 1.5×2cm, and place it in a plastic petri dish scrubbed with ethanol for use;

[0025] (2) Gently press the oil latent fingerprint on the surface of the PVDF film object to obtain the oil latent fingerprint-PVDF film;

[0026] (3) Configure CTAB solution and CNTs diluent;

[0027] (4) Drop the CTAB solution onto the surface of the latent fingerprint substrate and react for 10 minutes to obtain the oil latent fingerprint-PVDF film-CTAB;

[0028] (5) Immerse the positively charged oil latent fingerprint-PVDF film-CTAB obtained in step (4) in the CNTs diluent, react for 5 minutes, and rinse with ultrapure water after taking it out. Under natural light, you can directly use the naked eye Observe clear fingerprints; place the displayed oil latent fingerprint-PVDF film-CTAB-CNTs on a horiz...

Embodiment 2

[0030] Taking the appearance of latent fingerprints on the surface of NC film as an example, the specific operation has the following steps:

[0031] (1) Cut the NC film into a size of 1.5×2cm with scissors, and place it in a plastic petri dish scrubbed with ethanol for use;

[0032] (2) Gently press the oil latent fingerprint on the surface of the NC film object to obtain the oil latent fingerprint-NC film;

[0033] (3) Configure CTAB solution and CNTs diluent;

[0034] (4) Drop the CTAB solution onto the surface of the latent fingerprint substrate and react for 10 minutes to obtain the oil latent fingerprint-NC film-CTAB;

[0035] (5) Immerse the positively charged oil latent fingerprint-NC film-CTAB obtained in step (4) in the CNTs diluent, react for 10 minutes, rinse with ultrapure water after taking it out, and use the naked eye directly under natural light. Observe clear fingerprints; place the displayed oil latent fingerprint-NC film-CTAB-CNTs on a horizontal object, and take a ...

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Abstract

The invention discloses a method for displaying latent fingerprints on the front and back surfaces of different hydrophilic and hydrophobic materials, which belongs to the technical field of fingerprint identification. In this method, the latent fingerprints printed on the surface of different hydrophilic and hydrophobic materials are immersed in positively charged CTAB solution and negatively charged CNTs diluent successively, and are visualized by using the principle of hydrophilicity and hydrophobicity and electrostatic adsorption. Compared with the existing chemical deposition and small particle suspension technologies, the present invention can realize the positive and negative visualization of latent fingerprints according to the hydrophilicity and hydrophobicity of the substrate material, and is suitable for displaying latent fingerprints on the surface of various common semi-permeable and permeable objects , and the operation is simple, the raw materials are environmentally friendly and easy to obtain, the process is fast, the repeatability is good, and it does not need large-scale instruments, which can be used for on-site detection of latent fingerprints.

Description

Technical field [0001] The invention belongs to the technical field of fingerprint identification, and relates to the use of negatively charged carbon nanotubes (CNTs) diluent and cetyltrimethylammonium bromide (CTAB) solution on the surface of different hydrophilic and hydrophobic materials (PVDF film, NC film) And fingerprint tape, etc.) to reveal latent fingerprints. Background technique [0002] Fingerprints, also known as handprints. Due to multiple factors such as genetic material, skin tissue structure, pathology, and trauma, the specificity, diversity and stability of fingerprint lines are determined by the characteristics of different people, constant lifelong and leaving marks on touch. At the crime scene, common fingerprints are divided into three categories: obvious patterns, formed patterns and latent fingerprints. Latent fingerprints are not easy to find visually. They are the most common type of fingerprints at the crime scene and are the research object in this a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): A61B5/1172
Inventor 张美芹奥宁李小龙区云韵
Owner UNIV OF SCI & TECH BEIJING
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