Innovations in Biometric Identification: Role of Nanomaterials

To provide a setting for crime investigation that is admissible evidence in courts, the fingerprint detection method is essential. It is constructive for collecting information from weapon materials and conducting investigations at crime scenes. When perspiration from finger pores comes into contact with the skin, fingerprints are created. Sweat leaves behind unseen imprints, such as fingerprint ridge patterns. The latent fingerprint refers to the fingerprint's intangible character. Sweat from growing eccrine, sebaceous, and apocrine glands in the palm, head, and nose is the source of latent fingerprint detection. When minerals and organic components are present, sweat leaves the most residue on the pores of the fingers.

Powdering, vacuum metal deposition, and small particle reagents have all been used physically for fingerprint detection, if we are talking about analytical techniques to enhance latent fingerprint detection. Other compounds that have been used to enhance fingerprint detection include iodine, cyanoacrylate, and multi-metallic deposition. These materials are physical and chemical methods. To enhance the quality to obtain better photos and make latent fingerprint detection easier.

Digital devices used for fingerprint detection include fingerprint scanners and advanced nanotechnology devices designed to protect against phishing and account takeover fraud. Our research investigated various optical methods, including adsorption, UV-Vis spectroscopy, fluorescence spectroscopy, diffusion, and electrochemical methods, for detecting latent fingerprints. Additionally, lipid and amino acid derivatives have been identified as key components in latent fingerprint detection using thin-layer chromatography. Previous studies have focused on the development of latent fingerprints using solid-state ninhydrin on both porous and non-porous substrate surfaces. Ninhydrin and ink were applied to fingerprint residues on paper with the addition of acetone to minimise masking effects. Conversely, water-insoluble materials have been utilised in latent fingerprint detection through physical methods.

Nanomaterials are essential in fingerprint detection because of the electrostatic interactions with residues from fingertips, which consist of amino acids, fatty acids, and minute particles of silver waste.

In photographic processes, image developers help create visuals from photographs. Redox reagents, such as iron salts, can cause oxidation and discolouration in images. Typically, latent fingerprint images appear as dark grey photographs, resulting from the reaction between metallic silver particles and the lipids and fatty acids present in fingerprint residue. 

Detection powders made with silver are cost-effective and have good adhesive properties, making them effective for latent fingerprint detection. Silver particles adhere to the sweat and oily substances in the fingerprint ridges as fine powders. However, silver ink solutions are not ideal for latent fingerprint detection because they are expensive and require sophisticated equipment.

Silver nanoparticles (Ag NPs) are promising materials for developing latent fingerprint residues. During fingerprint detection, silver is converted into silver nanoparticles using iron salt as an oxidant, resulting in clear images on porous surfaces due to the oxidation and reduction processes involved. These nanoparticles exhibit grey and dark colours on the porous substrate. Gold nanoparticles (Au NPs) are also utilised for detection, with nanostructures showing promising potential in this area. NPs offer distinct advantages, such as selectivity, enhanced contrast, and high sensitivity. Metal nanoparticle solutions containing +ve and negatively charged ions can be easily deposited on substrate finger residues, leading to efficient oxidation. Au NPs demonstrate significant properties, including selectivity, sensitivity, stability, and long-term inertness for fingerprint detection. Additionally, TiO2 NPs powder shows excellent performance on black adhesive tape and has been employed in various suspensions and surfactants for fingerprint detection. Notable analytical techniques used to characterise TiO2 NPs include X-ray fluorescence (XRF), transmission electron microscopy (TEM), and laser particle sizing.

Table 1: Literature survey 

Year	Citation (short)	Method / Material	Surfaces / Use cases	Key result / metric (if reported)	Notes / significance
2020	Wang et al., JACS (2020). American Chemical Society Publications	Real-time fluorescence imaging for latent prints	Multiple non-porous surfaces	Rapid in-situ fluorescence visualization; demonstrated portable capture	Early demonstration of fluorescence methods for point-of-origin capture.
2022	Wang et al., RSC Adv. (2022) — Carbon dots for LFPs. RSC Publishing	Carbon dots (high QY fluorescent CDs)	Common non-porous and some porous substrates	Fast, bright emission; good contrast on complex backgrounds	Carbon dots: low-toxicity, water-dispersion and tuneable fluorescence.
2023	Assis et al., WIREs Forensic Sci. (2023) — review on nanomaterials. Wiley Online Library	Review — Au/Ag NPs, MMD, nanotech	Broad	Comprehensive review of metal NP deposition and nanomaterial approaches	Shows trend toward multifunctional nanoparticles and metal deposition techniques.
2023	Pinna et al., Sci. Reports (2023) — optically stimulated luminescence. ScienceDirect	Optically stimulated luminescence (OSL) imaging	Thin plastics, tape, foil, glass	Enhanced visualization on tricky plastics and adhesive surfaces	Optical/photonic methods help where powders/chemicals fail.
2023	Yu et al., Sensors/Review on fingerprint sensors (2023). PMC	Review — acquisition tech (optical, capacitive, ultrasonic)	Acquisition hardware (sensors)	Surveyed mechanism improvements and contactless trends	Important for forensic capture & mass-deployed biometric systems.
2023	Kothadiya et al., (2023) — liveness detection review. PMC	Liveness detection methods (anti-spoofing)	Biometric systems (authentication)	Improvements in sensor + ML pipelines for liveness checks	Liveness prevents bypassing biometric systems; affects field capture.
2024	Ruan et al., JACS (2024) — jellyfish GFP chromophore probes. American Chemical Society Publications	GFP-chromophore based fluorescent dyes (LFP-Yellow/LFP-Red)	Broad: porous and non-porous; rough surfaces	Visualize LFPs within ~10 seconds with portable system; water-soluble & low toxicity	High-impact: fast, biocompatible, preserves DNA; portable capture demonstrated.
2024	Alves et al., (2024) — Ag nanoparticle electrodeposition for LFPs. ScienceDirect	Silver nanoparticle electrodeposition on metal surfaces	Metal substrates (stainless steel, brass)	Strong contrast on metal — improved ridge detail	Targeted approach for metal evidence (tools, shells, etc.).
2024	Grover et al., Egyptian J Forensic Sci. (2024) — carbon dots review. SpringerOpen	Review — carbon dots for latent fingermarks	Broad	Summarizes CD syntheses, functionalization and forensic demonstrations	Carbon dots emerging as versatile, low-toxicity reagents.
2024	MCM-41 + chitosan + dansyl glycine fluorescent nanoparticle (univ. reports/press 2024). Phys.org+1	Porous silica (MCM-41) core functionalized nanoparticles	Complex and patterned backgrounds	Good adhesion to residues; high fluorescence contrast	Example of engineered nanoparticle to overcome patterned background issues.
2024	Singh et al., JFS / Forensic Sci. (2024) — nanomaterial developments. Lippincott Journals	Review / study on various nanomaterials for LFP development	Broad	Nanomaterials can reveal pores & minutiae; better fidelity on aged prints	Practical guidance for incorporating NPs in labs.
2024	Multiple media/reports summarizing bio-dyes & green approaches (2024). Phys.org+1	Biocompatible fluorescent sprays (GFP derivatives)	Field use; portable visualization	Rapid, water-based, preserves downstream DNA analysis	Trend toward safer, environmentally friendly reagents.
2025	Jain (2025) — rare-earth based and organic fluorophores reviews. ScienceDirect+1	Reviews — rare-earth, organic fluorophores	Broad	Survey of recent fluorophores and their applied techniques	Indicates continuing R&D into tailored fluorophores for LFPs.
2025	Mokal et al. (2025) — deep learning fingerprint classification. ScienceDirect	Deep learning for fingerprint classification/analysis	Biometric databases, behavior analysis	Automated models improving classification and matching	ML & DL increasingly integrated for both identification and image enhancement.
2024–25	Multiple comparative studies on traditional vs modern methods (2024–2025). Forensic Science Journal+1	Powder, ninhydrin, Oil Red O, Nile Red, nanoparticle/fluorophore methods	Porous / non-porous / challenging backgrounds	New reagents (silica gel G, dyes, NPs) often outperform traditional methods on difficult substrates	Many comparative studies recommend hybrid workflows (chemical + nano + optical).

Future Prospects

The integration of nanomaterials with artificial intelligence (AI) and machine learning has the potential to create more adaptive and intelligent biometric systems.

The development of eco-friendly nanomaterials will help address concerns about toxicity.

There is an opportunity to expand into multimodal biometrics by combining fingerprint, iris, DNA, and biochemical markers to achieve nearly foolproof identification.

Conclusion

Nanomaterials are revolutionising the field of biometric identification. By enhancing sensitivity, accuracy, and versatility, they pave the way for a new era of security systems that are not only more difficult to deceive but also more inclusive and reliable. As research advances, the fusion of nanotechnology with biometrics promises to make our digital and physical environments safer than ever. With accuracy and versatility, they pave the way for a new era of security systems that are not only more difficult to deceive but also more inclusive and reliable. As research advances, the fusion of nanotechnology with biometrics promises to make our digital and physical environments safer than ever. With accuracy and versatility, they pave the way for a new era of security systems that are not only more difficult to deceive but also more inclusive and reliable. As research advances, the fusion of nanotechnology with biometrics promises to make our digital and physical environments safer than ever. With accuracy and versatility, they pave the way for a new era of security systems that are not only more difficult to deceive but also more inclusive and reliable. As research advances, the fusion of nanotechnology with biometrics promises to make our digital and physical environments safer than ever. Accuracy and versatility pave the way for a new era of security systems that are not only more difficult to deceive but also more inclusive and reliable. As research advances, the fusion of nanotechnology with biometrics promises to make our digital and physical environments safer than ever. Accuracy and versatility pave the way for a new era of security systems that are not only more difficult to deceive but also more inclusive and reliable. As research advances, the fusion of nanotechnology with biometrics promises to make our digital and physical environments safer than ever.