System for the production of a metal-organic framework (MOG)-based luminescent composition for the detection of latent fingerprints

Abstract

A system for producing a metal-organic framework (MOG)-based luminescent composition for the detection of latent fingerprints, comprising: A unit for manufacturing the composition configured to produce a luminescent composition comprising one or more metal-organic frameworks (MOFs) designed for high-contrast, non-destructive visualization of latent fingerprints on porous, semi-porous, and non-porous substrates, wherein the unit for manufacturing the composition comprises: a) a MOF scaffolding unit configured to provide MOF scaffolds selected from a group consisting of the following: Zirconium-based, zinc-based, aluminum-based or rare-earth-based frameworks with large surface area and chemical robustness; b) an integration unit for luminescent centers configured to integrate luminescent centers into or onto the MOF framework, wherein the luminescent centers are selected from a group consisting of lanthanide nodes, ligand-centered emitters, or dye-sensitized guests to achieve strong emission under UV or visible excitation; and c) a surface modification unit configured to apply surface-modifying components that promote a selective affinity for fingerprint residues while minimizing background adhesion.

Description

AREA OF INVENTION

[0001] The present disclosure relates to the field of latent fingerprint detection. In particular, the present invention relates to a system for producing a luminescent composition based on a metal-organic framework (MOG) for the detection of latent fingerprints. BACKGROUND OF THE INVENTION

[0002] Latent fingerprint (LFP) detection is a fundamental aspect of forensic identification due to the unique, persistent, and individual characteristics of fingerprint patterns. Conventional detection techniques such as powder dusting, cyanoacrylate vapor deposition, ninhydrin treatment, and small-particle reagent methods are commonly used by law enforcement agencies. However, these traditional approaches have significant limitations when applied to challenging substrates, multicolored backgrounds, or old fingerprint residues. This often results in poor contrast and reduced detection sensitivity.

[0003] The development of nanomaterials enables alternative detection strategies with increased sensitivity and customizable optical properties. Metal-organic frameworks (MOFs), consisting of metal ions or clusters bound to organic ligands, represent a class of crystalline materials characterized by exceptional performance in chemical sensing and luminescence-based detection. MOFs offer advantageous properties such as a large surface area, customizable pore sizes, and the ability to incorporate functional guest molecules, making them particularly suitable for forensic detection applications.

[0004] Current luminescence detection systems lack the combination of non-destructive visualization, high contrast under UV or visible excitation, substrate versatility, and long-term stability required for comprehensive forensic applications. Furthermore, existing systems do not offer the adjustable emission wavelengths necessary for multicolor imaging in complex forensic environments with varying background interference.

[0005] Therefore, there is a need for improved luminescent compositions that overcome the limitations of conventional fingerprint recognition methods while offering improved sensitivity, selectivity, and flexibility of use across different substrate types and environmental conditions. Summary of the invention

[0006] The present disclosure relates to a system for producing a luminescent composition based on metal-organic frameworks (MOFs) for the detection of latent fingerprints. The system comprises integrated units for MOF framework fabrication, integration of luminescent centers, and surface modification to create compositions that enable high-contrast, non-destructive visualization of latent fingerprints on various substrate types. The composition fabrication unit produces luminescent MOF materials with tunable optical properties and selective affinity for fingerprint residues while minimizing background noise.

[0007] The present disclosure aims to provide a system for producing a luminescent composition based on a metal-organic framework (MOF) for the detection of latent fingerprints. The system comprises: a composition production unit that produces a luminescent composition from one or more metal-organic frameworks (MOFs) designed for the high-contrast, non-destructive visualization of latent fingerprints on porous, semi-porous, and non-porous substrates, wherein the composition production unit comprises: a) an MOF framework unit that provides MOF frameworks selected from the group consisting of: zirconium-based frameworks, zinc-based frameworks, aluminum-based frameworks, or rare-earth-based frameworks with a large surface area and chemical robustness;b) a unit for integrating luminescent centers, which integrates luminescent centers into or onto the MOF framework, wherein the luminescent centers are selected from the group consisting of: lanthanide nodes, ligand-centered emitters, or dye-sensitized nodes to achieve strong emission upon UV or visible excitation; and c) a surface modification unit configured to apply surface-modifying components that promote selective affinity for fingerprint residues while minimizing background adhesion.

[0008] One objective of the present disclosure is to provide a system for producing a luminescent composition based on a metal-organic framework (MOG) for the detection of latent fingerprints.

[0009] Another objective of the present disclosure is to provide a system for the production of MOF-based luminescent compositions that achieve higher contrast and higher sensitivity in the detection of latent fingerprints compared to conventional visualization methods.

[0010] Another objective of the present disclosure is to enable the non-destructive visualization of fingerprints on porous, semi-porous and non-porous substrates with minimal background adhesion.

[0011] Another objective of the present disclosure is to enable adjustable emission properties for multicolor imaging applications through various strategies for integrating luminescence centers.

[0012] To further clarify the advantages and features of the present disclosure, the invention is explained in more detail with reference to specific embodiments illustrated in the accompanying drawing. This drawing merely shows typical embodiments of the invention and is therefore not to be understood as limiting its scope. The invention is described and explained more precisely and in greater detail with reference to the accompanying drawing. BRIEF DESCRIPTION OF THE FIGURE

[0013] These and other features, aspects, and advantages of the present disclosure will be better understood if the following detailed description is read with reference to the accompanying drawing, in which the same symbols consistently represent the same parts. The following applies: Fig. Figure 1 illustrates a block diagram of a system for producing a metal-organic framework (MOG)-based luminescent composition for detecting latent fingerprints according to an embodiment of the present disclosure.

[0014] Experts will also recognize that the elements in the drawing are shown for the sake of simplicity and are not necessarily to scale. For example, the flowcharts illustrate the process by highlighting the main steps to enhance understanding of the aspects of this disclosure. Furthermore, with regard to the design of the device, one or more components of the device may be represented in the drawing by conventional symbols, and the drawing may show only the specific details relevant to understanding the embodiments of this disclosure, so as not to clutter the drawing with details that are readily apparent to those skilled in the art after reading this description. DETAILED DESCRIPTION:

[0015] For a better understanding of the inventive principles, reference is made below to the embodiment shown in the drawing, which is described in specific terminology. However, this does not limit the scope of the invention. Changes and further modifications of the illustrated system, as well as further applications of the inventive principles, are possible, as would normally occur to a person skilled in the art in the field of invention.

[0016] It is clear to the person skilled in the art that the preceding general description and the following detailed description are exemplary and explanatory of the invention and are not intended as a limitation of it.

[0017] References in this specification to “an aspect”, “another aspect”, or similar expressions mean that a particular feature, structure, or property described in connection with the embodiment is included in at least one embodiment of the present disclosure. Therefore, occurrences of the expressions “in one embodiment”, “in another embodiment”, and similar expressions in this specification may all refer to the same embodiment, but need not.

[0018] The terms "includes," "include," or other variations thereof are intended to cover non-exclusive inclusion, so that a process or method that includes a list of steps may not only contain those steps but may also include other steps not expressly listed or inherent in such process or method. Likewise, the statement "includes..." in the case of one or more devices, subsystems, elements, structures, or components does not, without further limitations, preclude the existence of other devices, subsystems, elements, structures, components, or additional devices, subsystems, elements, structures, or components.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as understood by a person skilled in the art in the field of the invention. The systems, methods, and examples provided herein serve only for illustration and are not to be construed as limitations.

[0020] Embodiments of the present disclosure are described in detail below with reference to the attached drawing.

[0021] Fig. Figure 1 shows a block diagram of a system (100) for producing a metal-organic framework (MOG)-based luminescent composition for detecting latent fingerprints according to an embodiment of the present disclosure.

[0022] Referring to Fig.1 The system (100) comprises: a composition manufacturing unit (102) configured to produce a luminescent composition comprising one or more metal-organic framework compounds (MOFs) designed for high-contrast, non-destructive visualization of latent fingerprints on porous, semi-porous, and non-porous substrates, wherein the composition manufacturing unit (102) comprises: a) an MOF framework unit (104) configured to provide MOF frameworks selected from a group consisting of: zirconia-based frameworks, zinc-based frameworks, aluminum-based frameworks, or rare-earth-based frameworks with a large surface area and chemical robustness;b) a unit for integrating luminescent centers (106) configured to integrate luminescent centers into or onto the MOF framework, wherein the luminescent centers are selected from a group consisting of: lanthanide nodes, ligand-centered emitters, or dye-sensitized nodes to achieve strong emission upon UV or visible excitation; and c) a surface modification unit (108) configured to apply surface-modifying components that promote selective affinity for fingerprint residues while minimizing background adhesion.

[0023] In one embodiment, the MOF scaffold unit (104) is configured to provide UiO-66-NH2 (Zr) scaffolds for hydrolytic stability and accessible amino sites, ZIF-8 (Zn(mIm)2) scaffolds for hydrophobic pores, or Ln-MOF scaffolds in which the lanthanide ion forms part of the node.

[0024] In one embodiment, the MOF scaffold unit (104) is configured such that the particle size can be adjusted between 200 nm and 5 µm, with a d 50 from 750 nm to 1.5 µm for optimized surface coverage.

[0025] In one embodiment, the integration unit of the luminescence center (106) is configured to provide intrinsic luminescence via amino terephthalate linkers with blue-green emission, lanthanide sensitization by coordination of TbCl3·6H2O or Eu(NO3)3·6H2O for sharp emission at 545 nm or 615 nm, respectively, or gas encapsulation of dyes selected from perylene diimide, coumarin 6, or rhodamine B.

[0026] In one embodiment, the surface modification unit (108) is configured to decorate the MOF surface with a mixed monolayer comprising cationic groups for salt-rich eccrine domains, hydrophobic chains for lipid-rich domains, and hydrogen bond donors / acceptors for stabilized adhesion to aged prints.

[0027] In one embodiment, the surface modification unit (108) is configured to functionalize the MOF surface by postsynthetic modification of side amino groups with alkyl bromides, epoxides or isothiocyanates or by polymer grafting via surface-initiated ATRP.

[0028] In one embodiment, the system (100) further comprises a formulation unit (110) configured to produce dry powder formulations by mixing MOF with 2-5 wt. % pyrogenic silica as a flow agent, wet dispersions comprising 1-5 mg / ml MOF in EtOH:H2O 70:30 with 0.02 wt. % non-ionic surfactant, or aerosol formulations in propellant canisters.

[0029] The present invention overcomes the limitations of conventional methods for detecting latent fingerprints by providing a sophisticated system for producing luminescent compositions based on metal-organic frameworks. The system integrates several specialized units for producing compositions with enhanced detection capabilities and substrate diversity. The composition manufacturing unit serves as the central component and orchestrates the production of luminescent MOF materials specifically designed for forensic applications. The MOF framework unit provides the basic framework by supplying various metal-organic frameworks selected from zirconium-, zinc-, aluminum-, or rare-earth-based materials.These scaffolds are characterized by a large surface area and chemical robustness, with particle sizes carefully tuned between 200 nm and 5 µm to optimize surface coverage and penetration into the groove features of the fingerprint. Specific MOF types include UiO-66-NH2 for hydrolytic stability, ZIF-8 for hydrophobic interactions, and lanthanide-based MOFs for integrated luminescent properties. The luminescence center integration unit allows for the incorporation of various emission sources to achieve strong luminescence under UV or visible excitation. The system supports multiple strategies, including intrinsic luminescence of aminoterephthalate linkers, lanthanide sensitization with terbium or europium compounds for sharp emission lines, and gas encapsulation of organic dyes.This versatility allows for tailored optical properties adapted to specific forensic requirements and environmental conditions. Surface modification is a critical aspect of the system. The surface modification unit applies specialized components that enhance the selective affinity for fingerprint residues. The unit creates mixed monolayers of cationic groups for interaction with salt-rich eccrine components, hydrophobic chains for lipid-rich domains, and hydrogen bond donors / acceptors for the detection of aged fingerprints. Functionalization is achieved through postsynthetic modification or polymer grafting techniques to ensure stable attachment and optimal performance.

[0030] The formulation unit offers added flexibility by providing various dosage forms, including dry powders with flow agents, wet dispersions with optimized solvent ratios, and aerosol formulations for convenient application. This comprehensive approach ensures the effective use of the luminescent MOF compositions in diverse forensic scenarios and substrate requirements while maintaining detection sensitivity and ease of use.

[0031] In one implementation, MOF scaffold selection is based on a preferred scaffold, which includes: UiO-66-NH2 (Zr) due to its hydrolytic stability and accessible amino sites, ZIF-8 (Zn(mIm)2) due to its hydrophobic pores and ease of synthesis at room temperature, and Ln-MOFs where the lanthanide ion forms part of the node. The particle size can be adjusted between 200 nm and 5 µm, with smaller particles penetrating the microstructures of the ridges (level 3), while larger particles (1–3 µm) reduce the inhalation risk and dust loss. A dso of 750 nm–1.5 µm is advantageous for most surfaces.

[0032] In one implementation, the integration of the luminescence center is achieved through the use of three different approaches: intrinsic, lanthanide sensitization, and gas encapsulation. The intrinsic approach involves the use of UiO-66-NH2, an amino terephthalate linker with blue-green emission, where the introduction of scaffold defects improves the radiation pathways. The lanthanide sensitization approach involves the postsynthetic incorporation of TbCl3·6H2O or Eu(NO3)3·6H2O by coordination to defect sites or chelating side arms such as grafted 1,10-phenanthroline-5,6-dione, with the linker acting as an antenna and exhibiting sharp emission at 545 nm (Tb3). +) or 615 nm (Eu3 +)This enables long lifetimes (ms), thus facilitating time-controlled imaging. The gas encapsulation approach involves the use of dyes, including perylene diimide, coumarin 6, and rhodamine B, which enter the pores via solvent exchange. Electrostatic or size exclusion interactions prevent leaching during short rinsing cycles.

[0033] In one implementation, the system is configured to perform surface functionalization of the prepared MOF surface. To exploit the amphiphilic nature of fingerprint residues, the MOF surface is decorated with a mixed monolayer, the monolayers comprising the following: • Cationic groups (e.g. [-CH2-N + (CH3)3] Cl -) for salt-rich eccrine domains. • Hydrophobic chains (C 12 -C 16 ) for lipid-rich domains. • Hydrogen bond donors / acceptors (e.g., urea, amide) to stabilize adhesion on aged prints where oxidation alters the residue chemistry.

[0034] In one implementation, the system is configured to perform surface functionalization by postsynthetic modification (PSM) of attached amino groups with alkyl bromides, epoxides or isothiocyanates, or by polymer plugging (e.g., poly(ionic liquid) brushes) via surface-initiated ATRP.

[0035] In this implementation, three formulations are developed, including a dry powder, a wet dispersion, and an aerosol. The dry powder is prepared by mixing MOF with 2–5 wt% pyrogenic silica as a flow agent; sieving ensures uniform distribution. The wet dispersion is prepared from 1–5 mg / ml MOF in EtOH : H₂O 70:30 with 0.02 wt% nonionic surfactant (e.g., polysorbate 20). The aerosol is prepared by filling the dispersion into a blowing agent container such as HFO-1234ze and maintaining particle stability with trace amounts of PVP (≤ 0.1 wt%).

[0036] In one embodiment, the system enables the development of latent fingerprints and comprises various units and components. The system includes a dry development unit configured to preserve evidence under ambient conditions of 15–30 °C and a relative humidity of 30–70%. The dry development unit incorporates soft fiber brushes selected from squirrel, glass fiber, or magnetic rod configurations for magnetizable MOF composites. The unit allows for the gentle dispersal of powder over suspicious areas through electrostatic and hydrophobic interactions that attract particles to groove residues. The dry development unit features an excess particle removal device that removes excess particles by gentle puffs of air or tapping, while avoiding strong jets of air on delicate prints.The unit includes an illumination system that enables excitation at 365 nm or 405 nm and corresponding emission collection filters. The system also includes a wet application unit that sprays the dispersion at a shallow angle from a distance of approximately 20–30 cm, ensuring uniform distribution with residence times of 20–60 seconds. The wet application unit includes a rinsing device configured with a light ethanol rinse to remove background adsorbed particles. The unit includes a drying device that provides a gentle airflow for sample drying, as well as an imaging device, as specified in the dry development configuration. The system also includes a post-evaporation unit that performs cyanoacrylate vapor deposition to stabilize sensitive prints.The post-evaporation unit is configured to apply a MOF dispersion to positively charged surfaces of polymerized CAF residues. The unit enables the attraction of MOF particles, resulting in bright luminescence without the need for additional dyes. The system also includes a multicolor imaging unit, which... 3+ for green emission on colored substrates with a red background, EU 3+ It is used for red emission on green-tinted substrates or blue-emitting, dye-loaded MOFs on warm backgrounds. The multicolor imaging unit includes ratiometric particle equipment that incorporates internal normalization by Tb. 3+ / Eu 3+Combinations are possible, with the G / R ratio mapping equipment configured to determine burr thickness or aging state. An imaging and recording unit of the system is configured for use with portable lamps with 254 nm, 365 nm, or 405 nm excitation and DSLR or smartphone camera equipment with attachable bandpass filters. The imaging unit includes time-delayed imaging equipment configured for pulsed UV excitation with acquisition capabilities after a 50–200 µs delay to suppress short-lived background fluorescence.

[0037] The present invention provides a system for the production of luminescent compositions based on metal-organic framework compounds (MOF) using a one-pot solvothermal process employing trivalent lanthanide centers (Tb). 3+ , Eu 3+) and a rigid π-conjugated dicarboxylate linker. Powder X-ray diffraction (PXRD) confirmed phase purity with no residual precursor peaks. SEM / TEM showed uniform, nearly spherical crystallites (400–900 nm, CV ~12%), and BET analysis revealed surface areas of 620–760 m². 2 G -1 , which corresponds to a micro- / mesoporous texture. EDS and ICP confirmed a homogeneous metal distribution and stoichiometry, while TGA showed stability up to ~330 °C.

[0038] Photoluminescence spectra under near-UV excitation (365–395 nm) showed sharp lanthanide emissions (⁵D⁴→⁷F⁻J for Tb, ⁵D⁰→⁷F⁻J for Eu) with quantum yields of 38–47% (Tb) and 31–39% (Eu). Co-doping with 5–10 mol% secondary lanthanides allowed for tuning of the emission color without loss of brightness. Long lifetimes (Tb: 0.8–1.3 ms; Eu: 0.4–0.7 ms) enabled time-controlled imaging. The antenna effect was confirmed by ligand absorption (~310–340 nm) and near-complete ligand quenching. The emission was stable under varying humidity (20–80% relative humidity) and at a pH of 5–9.

[0039] Optimization with pyrogenic silica (30 wt%) and trace amounts of nonionic surfactants (0.05 wt%, HLB 12-14) improved flowability, reduced agglomeration, and increased edge-to-background contrast. The mixture retained its hydrophobicity (contact angle ~98°) for lipid adhesion, while the surfactant improved wetting of eccrine residues.

[0040] Latent fingerprints on various substrates (glass, metal, ceramic, adhesive tape, varnished wood, polymer banknotes, polyethylene, copy paper) were developed by brushing and imaged under 365 / 395 nm excitation using long-pass filters. Both Tb- and Eu-based powders produced high-contrast, sharp burr patterns with low background. Quantitatively, the contrast-to-noise ratios were 8.6 ± 2.1 (Tb) and 7.9 ± 1.8 (Eu), exceeding those of commercially available fluorescent powders (5.2 ± 1.6). Level 2 features were consistently visible, and Level 3 pores were resolved in approximately 74% of prints on non-porous substrates. Inter-operator reproducibility was high (ICC = 0.87).

[0041] Aging studies showed forensically usable prints on non-porous surfaces for up to 30 days (~65% CNR retention), with reduced retention on porous substrates (-40% after 30 days). Heat treatment (60 °C, 2 h) caused a fluorescence loss of approximately 10% but preserved the burr details; water rinsing partially removed particles, but prints remained legible. On dust / soil-contaminated prints, the MOF showed burr details in 68% of cases, surpassing commercial powders (43%). On multi-colored backgrounds, the Tb / Eu co-doping enabled ratiometric channel selection, thus reducing spectral overlap.

[0042] The substrate-specific findings included: • Non-porous: High fidelity reproduction, with Eu-rich formulations that are superior on anodized aluminum. • Adhesive tape: strong burr contrast with minimal adhesive background. • Porous substrates: successful, but varying; pre-moistening improved clarity. • Low-energy plastics: The optimized formulation resulted in legible prints in 72% of cases compared to 49% for the benchmarks.

[0043] Compatibility tests showed DNA recovery from smeared fingerprints with only 8-12% yield loss, without significant allele loss. Subsequent ninhydrin treatment on paper was not affected by residual MOF.

[0044] Time-controlled imaging (20-50 µs delay, 1-3 ms gate) suppressed substrate autofluorescence and improved the CNR by 25-40%. Multispectral acquisition further improved the contrast; co-doped samples allowed switching of the emission channels (green / red) with identical excitation.

[0045] Mechanistically, selective adhesion is based on (i) the matching of surface energy and capillarity, (ii) the adsorption of LFP components to guest structures and framework structures, and (iii) the insensitivity of the 4f-4f transitions of the lanthanides to the environment.

[0046] Lift tests confirmed successful transfer to gelatin lifters and adhesive films with stable fluorescence for at least four weeks (<10% PL loss).

[0047] Practical studies confirmed free-flowing powders with minimal inhalation risk (particle size >300 nm), stable packaging, and easy handling with standard brushes and UV-A lamps. Comparative studies showed better CNR and pore recovery than commercially available fluorescent powders, faster application than CA vapor deposition, and suitability as a rapid triage tool on porous substrates.

[0048] In one embodiment, the latent fingerprint development composition exhibits one or more limitations, including reduced robustness on aged porous prints (> 1 month), slight background blurring on highly porous paper, and dependence on UV-A excitation. Advantages include anti-caking agents, red-shifted linkers for 405–450 nm excitation, and surface modifications for residual type selectivity. The latent fingerprint development composition demonstrated high-contrast fingerprint recovery on various substrates, resistance to aging and environmental stresses, imaging flexibility (time windowing and multispectral switching), workflow compatibility with DNA and chemical reagents, and practical field application.

[0049] The drawing and the preceding description show examples of embodiments. Those skilled in the art will recognize that one or more of the described elements can be combined to form a single functional element. Alternatively, certain elements can be divided into several functional elements. Elements of one embodiment can be added to another embodiment. For example, the sequence of the processes described here can be changed and is not limited to the manner described here. Furthermore, the actions of a flowchart need not be implemented in the sequence shown; nor does it necessarily have to be performed by all actions. Actions that are not dependent on other actions can also be performed in parallel with the other actions. The scope of the embodiments is in no way limited by these specific examples.Numerous variations are possible, whether explicitly stated in the specification or not, such as differences in structure, dimensions, and material usage. The range of embodiments is at least as broad as specified in the following claims.

[0050] Advantages, further benefits, and problem solutions have been described above with reference to specific embodiments. However, the advantages, benefits, problem solutions, and all components that can lead to an advantage, benefit, or solution occurring or becoming more apparent are not to be construed as critical, necessary, or essential features or components of individual or all claims. REFERENCES 100 A system for the production of a metal-organic framework (MOG) based luminescent composition for the detection of latent fingerprints. 102 Composition preparation unit 104 MOF scaffolding unit 106 Luminescence Center - Integration Unit 108 Surface Modification Unit 110 formulation unit

Claims

[1] A system for producing a metal-organic framework (MOG) based luminescent composition for the detection of latent fingerprints, comprising: A unit for manufacturing the composition configured to produce a luminescent composition comprising one or more metal-organic frameworks (MOFs) designed for high-contrast, non-destructive visualization of latent fingerprints on porous, semi-porous, and non-porous substrates, wherein the unit for manufacturing the composition comprises: a) a MOF scaffolding unit configured to provide MOF scaffolds selected from a group consisting of the following: Zirconium-based, zinc-based, aluminum-based or rare-earth-based frameworks with large surface area and chemical robustness; b) an integration unit for luminescent centers configured to integrate luminescent centers into or onto the MOF framework, wherein the luminescent centers are selected from a group consisting of lanthanide nodes, ligand-centered emitters, or dye-sensitized guests to achieve strong emission under UV or visible excitation; and c) a surface modification unit configured to apply surface-modifying components that promote a selective affinity for fingerprint residues while minimizing background adhesion. [2] System according to claim 1, wherein the MOF scaffold unit is configured to provide UiO-66-NH2 (Zr) scaffolds for hydrolytic stability and accessible amino sites, ZIF-8 (Zn(mIm)2) scaffolds for hydrophobic pores or Ln-MOF scaffolds in which the lanthanide ion forms part of the node. [3] System according to claim 1, wherein the MOF scaffold unit is configured such that the particle size can be adjusted between 200 nm and 5 µm, with a d 50 from 750 nm to 1.5 µm for optimized surface coverage. [4] System according to claim 1, wherein the integration unit of the luminescence center is configured to provide intrinsic luminescence by means of amino terephthalate linkers with blue-green emission, lanthanide sensitization by coordination of TbCl₃·6H₂O or Eu(NO₃)₃·6H₂O for sharp emission at 545 nm or 615 nm respectively, or gas encapsulation of dyes selected from perylene diimide, coumarin 6, or rhodamine B. [5] System according to claim 1, wherein the surface modification unit is configured to decorate the MOF surface with a mixed monolayer comprising cationic groups for salt-rich eccrine domains, hydrophobic chains for lipid-rich domains and hydrogen bond donors / acceptors for stabilized adhesion to aged prints. [6] System according to claim 1, wherein the surface modification unit is configured to functionalize the MOF surface by postsynthetic modification of side amino groups with alkyl bromides, epoxides or isothiocyanates or by polymer grafting via surface-initiated ATRP. [7] System according to claim 1, further comprising a formulation unit configured to produce dry powder formulations by mixing MOF with 2 to 5 wt. % pyrogenic silica as a flow agent, wet dispersions comprising 1 to 5 mg / ml MOF in EtOH:H2O 70:30 with 0.02 wt. % non-ionic surfactant, or aerosol formulations in propellant canisters.

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