Label-Free Chemical Imaging of Latent Fingerprints with Stimulated Raman Scattering Microscopy

Abstract

Fingerprints have long been the gold standard for personal identification in forensic investigations. Methods for cultivating and enhancing the visualization of latent fingerprints (LFPs) are continuously evolving. One important challenge is to identify suspicious chemicals present in fingerprint residues, which requires chemical imaging capability. Recently, vibrational spectroscopy has shown that LFP analysis through tape-lift, Raman mapping, and multivariate data analysis presents a useful tool for forensic investigation. However, there are still major difficulties in terms of acquisition speed, poor spatial resolution, and lack of sensitivity. This paper demonstrates the feasibility of stimulated Raman scattering microscopy to quickly and easily extract LFP patterns from different substrates. Contrary to what has been reported, no obvious fingerprint degradation or lipid diffusion is observed with either glass or stainless steel substrate. Importantly, we demonstrate that trace exogenous chemicals can be detected in fingerprints. We further demonstrate an improvement in directly acquiring a LFP pattern lifted from tape by spectrally removing signals from tape.

Denoising of stimulated Raman scattering microscopy images via deep learning

“…SRS images were acquired using a homebuilt SRS microscope as described previously [29][30][31] and as shown in Fig. 1.…”

Broadband hyperspectral stimulated Raman scattering microscopy with a parabolic fiber amplifier source

“…Additionally, the spectral resolution of most current systems is limited to ~20-25 cm −1 [46,47]. While these capabilities are often sufficient for imaging in the high wavenumber region (2800-3050 cm −1 ), they are insufficient for imaging in the fingerprint region (700-1800 cm −1 ).…”

Recent Trends in Fluorescent Organic Materials for Latent Fingerprint Imaging

“…Nowadays, many methods exist as standard methods for the development of the LFPs on common substrates in routine forensic practice (Ezhilmaran and Adhiyaman, 2017 ; Lennard, 2020 ), but there are still some situations that it is difficult or impossible to recover LFPs for forensic investigators. The ongoing research is being directed at improved sensitivity, universality, convenience, and efficiency via the optimization of existing methods or new approaches, such as spectroscopy, mass spectrometry, immuno-labeling, and nanoparticles based approaches (Nakamura et al, 2015 ; Zhao et al, 2016 ; Figueroa et al, 2017 ; O'Neill et al, 2018 ; Kolhatkar et al, 2019 ; Bodelón and Pastoriza-Santos, 2020 ; Li et al, 2020 ).…”