Report Explores Automated Dye Molecule Extraction

A new technical report, "Microfluidic System for Automated Dye Molecule Extraction and Detection for Forensic Fiber Identification," has been made available by NIJ through the National Criminal Justice Reference Service.


The report—written by Thomas Dow, David Hinks, Kenneth Garrard, Alexander Sohn, Stephen Furst, Min Li, Sean Gunning, and Nelson Vinueza—discusses automated processes for extracting dyes for fiber identification.

From the abstract:

Due to the quantity of textile materials in the environment, there is a high probability of fiber transfer during the commission of a crime. As a result, identification of fiber samples often plays a critical role in criminal investigations.

In a typical case, a sample of known origin must be compared to an evidence sample to determine if both could have the same origin.

A wide variety of techniques are available to test this hypothesis beginning with non-destructive visual comparison of characteristics, such as material, color, diameter, cross-sectional shape, birefringence, refractive index and fluorescence. One way to add additional specificity is to identify the dyes used to color the fabric. Such an analysis is more sensitive, but because it destroys the evidence, must be efficient and use a small sample.

The two major goals of this project were to produce a microfluidic device capable of automated extraction of dye from fibers and to design the components to provide optimum performance.

Automating processes such as fiber analysis and making them more repeatable and reliable has the potential to pay dividends in the search for a more equitable and thorough justice system with fewer false convictions and more successful prosecutions.

This research effort was split between chemists in Textile Chemistry and engineers and computer scientists in the Precision Engineering Center. The textile focus was to find the optimum extraction conditions for hundreds of fabrics and dye combinations. On the other hand, the Precision Engineering Center developed an automated device that used these conditions to extract the dye from a minute fabric sample.

One conclusion that can be taken from this project is that automated lab on a chip devices using timed flow control, heating, and convective evaporation on a microliter scale can operate successfully and consistently. It has also been shown that these automated systems can be used for trace sample detection purposes.

The technology has potential for use in any process that requires small scale extraction of molecules from solid materials. To provide a more general use, the capabilities of the system can be expanded to provide multiple solvents.

You can download the full paper here.

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