Skip to main content

Research Repository

Advanced Search

Nile red-dye based analysis of synthetic fibres for forensic applications.

Devalla, Sandhya; Joseph, Osheen; Prabhu, Radhakrishna


Sandhya Devalla

Osheen Joseph


Henri Bouma

Robert J. Stokes

Yitzhak Yitzhaky


Forensic evaluation of crime scenes normally involves examination of textile fibers, to find out the association between an individual and a crime scene, or between a suspect and a victim. The forensic samples normally include a mix of various types, sizes (micro to nano - scale) and shapes of natural and synthetic fibers, which are very difficult to differentiate/identify. Various sophisticated analytical instruments are being used to carry out the examination of these fibers. They involve various microscopy and spectroscopy based techniques, most of which are very complex and highly sensitive. Further, they may require a series of sample preparation steps to get high selectivity and are highly time consuming. Here we report a fluorescence microscopy based synthetic (plastic) fiber detection method using Nile Red (NR) dye, which provides high selectivity for synthetic fibers. The methodology involves the use of NR dye which selectively stains the fibers collected on filter papers following separation from samples/soils and water. The selectivity of NR towards the fibers is due to their non-polar property. Binding with NR makes the fibers fluoresce when viewed under a fluorescence microscope. This selectivity of NR for fibers makes the identification of fibers lot easier and less timeconsuming in forensic samples when compared to the more commonly used optical microscopy (where the presence of naturally-occurring substances of similar size can result in more errors). The paper will discuss optimisation of various parameters and method validation for detection of synthetic fibers and microplastics from soil samples. As an example, our method has shown to provide distinct clarity for the analysis of microfibers. The potential for the application of the method for faster forensics analysis will be discussed.

Start Date Sep 9, 2019
Publication Date Oct 7, 2019
Publisher Society of Photo-optical Instrumentation Engineers
Volume 11166
Series Title Proceedings of SPIE
Series ISSN 0277-786X
ISBN 9781510630352; 9781510630369
Institution Citation DEVALLA, S., JOSEPH, O. and PRABHU, R. 2019. Nile red-dye based analysis of synthetic fibres for forensic applications. In Bouma, H., Prabhu, R., Stokes, R.J. and Yitzhaky, Y. (eds.) Proceedings of the 3rd Counterterrorism, crime fighting, forensics, and surveillance technologies conference 2019: co-located with the Society of Photo-Optical Instrumentation Engineers (SPIE) Security and defence 2019 conference, 9-12 September 2019, Strasbourg, France. Proceedings of the SPIE, 11166. Bellingham, WA: SPIE [online], article ID 111660Y. Available from:
Keywords Forensic science; Luminescence; Microscopy; Error analysis; Microscopes; Optical filters; Optical microscopy; Spectroscopes


You might also like

Downloadable Citations