Fluorescent Development Reagent for Porous Carrier Trace Evidence
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Solution Overview
Problem
Current methods for collecting and analyzing biological trace evidence, such as fingerprints on porous carriers like fabrics, face challenges due to discontinuous lines and breakpoints, making it difficult to identify suspects accurately, and DNA extraction from non-obvious traces is labor-intensive and inefficient.
Innovation Solution
A method using a biological fluorescent development reagent with a specific formulation of indanedione, ethyl acetate, glycerol, pure alcohol, and petroleum ether, applied to porous carriers, followed by controlled drying and irradiation with a laser of specific wavelength and illuminance, to develop and extract biological trace evidence, including fingerprints and handprints, allowing for accurate DNA information extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional fingerprint development methods are used on porous carriers like fabrics, then the fingerprint can be developed, but the lines become discontinuous with breakpoints, reducing identification accuracy
Solution Approach 1:
The patent changes the chemical parameters of the development reagent by using indanedione as the active ingredient combined with specific solvents (ethyl acetate, glycerol, pure alcohol, and petroleum ether) in precise proportions. This chemical parameter change enables continuous fingerprint line development on porous carriers, resolving the discontinuity issue and improving identification accuracy.
Solution Approach 2:
The patent creates a composite development reagent system combining indanedione with multiple solvents (ethyl acetate, glycerol, pure alcohol, and petroleum ether) in specific ratios. This composite material approach enhances the reagent's ability to penetrate porous carriers while maintaining fingerprint line continuity, thereby improving both measurement precision and reliability.
2Difficulty of detecting and measuring
If blue light illumination is used to check DNA at the crime scene, then obvious traces like blood can be identified, but the workload becomes huge and non-obvious traces are difficult to find
Solution Approach 1:
The patent uses fluorescence technology to induce color changes in biological traces. The indanedione-based reagent reacts with amino acids in biological materials to produce fluorescent compounds that emit visible light under laser illumination. This color/fluorescence change makes both obvious and non-obvious traces detectable, reducing investigation workload while maintaining high trace visibility.
Solution Approach 2:
The patent replaces the manual blue light inspection method with an automated fluorescent development system using laser illumination and optical filters. This substitution eliminates the need for manual examination of each trace, dramatically improving productivity while enhancing the detection of non-obvious traces through the specific fluorescent reaction.
3Productivity
If fingerprint photos from fabrics are compared with database fingerprints, then suspects can be screened, but many false suspects appear or no suspects are found, making evidence collection difficult
Solution Approach 1:
The patent improves fingerprint matching accuracy by changing the development parameters to produce continuous, high-contrast fingerprint lines on porous carriers. The optimized reagent formulation and controlled drying conditions (temperature and humidity parameters) ensure that fingerprint details are preserved with high fidelity, enabling accurate database matching and reducing false positives or negatives.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables targeted extraction of physical evidence, reducing the workload and difficulty in obtaining evidence, improving investigation efficiency by producing clear and accurate biological trace evidence from porous carriers, such as fabrics, and facilitating the identification of suspects.
Implementation Method 1
using a biological fluorescent development reagent to process a porous carrier so as to develop biological trace evidence on the porous carrier
Implementation Method 2
a raw material formulation of the biological fluorescent development reagent is, in percent by weight: 0.01% - 0.5% of indanedione, 4% - 10% of ethyl acetate, 0.5% - 1.5% of glycerol, 5% - 15.5% of pure alcohol, and 73.5% - 90% of petroleum ether
Implementation Method 3
irradiating the dried porous carrier with a laser having a wavelength of 532 nm and a full width at half-maximum of less than 1 nm, controlling a surface of the porous carrier with an illuminance of over 300,000 lux
Implementation Method 4
irradiating the dried porous carrier with a laser having a wavelength of 532 nm and a full width at half-maximum of less than 1 nm
Implementation Method 5
using a cut-off filter under 540 nm to develop the biological trace evidence on the porous carrier
Implementation Method 6
drying the porous carrier in an environment having a relative humidity of less than 40% at a temperature of 50 °C - 120 °C
Data Source
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AI summary
A method for developing and extracting biological trace evidence comprises the following steps: (1) using a biological fluorescent development reagent to process a porous carrier so as to develop biological trace evidence on the porous carrier, wherein a raw material formulation of the biological fluorescent development reagent is, in percent by weight: 0.01% - 0.5% of indanedione, 4% - 10% of ethyl acetate, 0.5% - 1.5% of glycerol, 5% - 15.5% of pure alcohol, and 73.5% - 90% of petroleum ether; and (2) extracting the biological trace evidence to obtain DNA information of the biological trace evidence. In the method, a biological fluorescent development reagent is used to develop biological trace evidence, and then DNA information of the biological trace evidence is extracted, and the extracted DNA is compared and screened to finally find a suspect. For crime investigators who need to extract DNA evidence, the method enables targeted extraction of physical evidence, thereby greatly reducing workload, and furthermore, the method can also be used to develop and extract obscure or trace evidence, such as a fingerprint on a garment, thereby greatly improving investigation efficiency.