Near Infrared-to-Near Infrared Upconversion Nanocrystals for Latent Fingerprint Development

Abstract

The advantages of near infrared (NIR)-to-visible upconversion nanoparticles (UCNP) for latent fingerprint development have been previously documented. In the present study, the use of NIR-to-NIR UCNP, composed of β-NaYF4:2%Tm, 48%Yb, is evaluated for latent fingerprint analysis. Here, 976 nm illumination is used to generate 800 nm luminescent fingerprint images. NIR-to-NIR UCNP are demonstrated to have significant advantages over NIR-to-visible UCNP in developing latent fingerprints. NIR-to-NIR UCNP are significantly brighter than NIR-to-green β-NaYF4:2%Er, 18%Yb UCNP of comparable size, so that lower irradiance is required to obtain high-quality images. The increased brightness is due mainly to the much higher internal quantum yield of the NIR-to-NIR UCNP at the irradiance levels used for imaging. Imaging at 800 nm often significantly reduces the background interference from substrates with complex printed patterns because many inks do not absorb appreciably at 800 nm. In most instances, imaging can be performed in full room lighting without significant degradation of the image because modern lighting produces very little output in the NIR. Using β-NaYF4:2%Tm, 48%Yb@NaYF4 core–shell nanoparticles, fingerprints can be imaged easily using excitation irradiance levels below 100 mW·cm–2. The intrinsic quantum yields of the NIR-to-NIR upconversion are estimated for the nanomaterials used in this study at typical irradiance levels used here to image fingerprints. It is shown that the method for processing as-synthesized UCNP into powders has significant impact on the effective particle size in fingerprint development and on how the particles coat the fingerprint residue. The method demonstrated here produces fingerprint images of high resolution, as evidenced by the high number of minutiae which can be identified.

2021 National Institute of Justice Forensic Science Research and Development Symposium

“…Travis W. Over the past 3 years, our research group has been focusing on using upconverting nanoparticles (UCNPs, β-NaYF4:Yb/Tm) to develop fingerprints. This effort was successful with oleic acid-capped near-infrared (NIR)-emitting UCNPs (Baride et al, 2019). More recently, we have been focused on developing a system for reading fingerprints with UCNPs and for altering the UCNP surface such that DNA within the fingerprint can be captured and examined.…”

Lanthanide-Doped Upconversion Nanomaterials: Recent Advances and Applications

“…For effective fingerprint imaging in full room light, NIR-to-NIR UCNP can be used, which is significantly brighter than NIR-to-visible UCNP (Figure 7). Images obtained at 800 nm suffer less from the background signal noise interference on substrates; this is because numerous inks cannot absorb at the 800 nm emission wavelength of NIR-to-NIR UCNP 60 .…”

“…Figure 7. Latent fingerprints developed with NIR-to-NIR (top row) and NIR-to-visible (bottom row) UCNP60 . Images reproduced from the references with permission.…”

Efficiency of Thermally Activated Delayed Fluorescence Sensitized Triplet Upconversion Doubled in Three‐Component System

“…This process has been utilized in varied applications such as forensic and in situ biological imaging, temperature and mechanical stress sensing, as well as solar energy generation. [ 1–5 ] TTA‐UC has gained great attention because it can proceed efficiently at low threshold intensities of incident incoherent light at or below 100 mW cm −2 . [ 1,6,7 ] This phenomenon was first discovered in single molecules of anthracene and phenanthrene as early as 1962, [ 8 ] continued research has produced increasingly efficient TTA‐UC systems and revealed the ease of tuning optical properties in multicomponent systems.…”