Identification of Forensic Fabrics Using a Portable Raman Spectrometer

Significance of the Topic

Raman spectroscopy offers high selectivity, non-destructive analysis, and minimal sample preparation for rapid identification of forensic fibers.

Objectives and Study Overview

This study evaluated the performance of a portable Raman spectrometer in identifying six undyed fabric types commonly encountered at crime scenes.

Methodology and Instrumentation

• Tested fabrics: diacetate, bleached cotton, polyester, polyamide (nylon), acrylic, wool
• Instrument: B&W Tek i-Raman EX portable Raman spectrometer with 1064 nm laser excitation
• Accessory: Raman Video Micro-Sampling System with 20× objective and fiber optic probe holder
• Software: BWID Standard Raman ID for library creation and hit quality index (HQI)-based matching

Main Results and Discussion

• Diacetate, bleached cotton, polyamide, and acrylic were unambiguously identified with HQI ≥ 80 based on distinct Raman signatures.
• Polyester and wool exhibited similar spectra; differentiation relied on protein-specific bands.
• Wool was distinguished by an amide I band at 1653 cm⁻¹ and a disulfide S–S band at 523 cm⁻¹ associated with keratin.

Benefits and Practical Applications

• Enables rapid on-site and laboratory analysis within minutes.
• Non-destructive testing preserves valuable forensic samples.
• Eliminates sample preparation, reducing contamination risk and analysis time.

Future Trends and Opportunities

• Expanding spectral libraries for broader textile and fiber databases.
• Integrating portable Raman devices into automated crime scene workflows.
• Applying advanced chemometric methods to improve discrimination of complex mixtures.
• Exploring multi-wavelength Raman approaches to detect dyes and additives.

Conclusion

Portable Raman spectroscopy proves to be a powerful tool for forensic fabric analysis, offering rapid, accurate, and non-destructive identification of fibers in both field and laboratory settings.

Instrumentation Used

• B&W Tek i-Raman EX portable Raman spectrometer (1064 nm excitation)
• BWID Standard Raman ID Software for library generation and identification
• Raman Video Micro-Sampling System with 20× objective and fiber optic probe holder

References

1. Li-Ling Cho. Identification of textile fiber by Raman microspectroscopy. J Forensic Science. 2007;6(1):55-62.