WO2017114572A1

WO2017114572A1 - Security tag with laser-cut particles of biological origin

Info

Publication number: WO2017114572A1
Application number: PCT/EP2015/081407
Authority: WO
Inventors: Danica PAVLOVIC; Vladimir LAZOVIC; Aleksandar KRMPOT; Mihailo RABASOVIC; Dejan Pantelic
Original assignee: Institute Of Physics Belgrade, University Of Belgrade
Priority date: 2015-12-30
Filing date: 2015-12-30
Publication date: 2017-07-06

Abstract

The invention is directed to a security device individualized by permanently attaching precut and arranged particles of biological origin, possessing large variability of optical effects and complexity of internal structure. The shape of precut particles and their arrangement is chosen to maximize variability and complexity, while having durability, tamper sensitivity, micron size thickness, and capability to store the information using additional processing. A security tag, comprising a transparent substrate (6); an arrangement of processed biological particles (9) in a specific pattern which is attached to the substrate (6); and a transparent superstrate (10), having a recess (11), and adhering to the substrate (6) and enclosing the biological particles (9); as well as a method to manufacture said tag, suitable for visual, machine and forensic inspection, are disclosed.

Description

Security tag with laser-cut particles of biological origin

Field of Invention

The present invention relates to security tags for identification and authentication of goods, articles and documents. Background of Invention

Optically variable devices (OVD) are a common protective element on various types of documents (e.g. identity cards, passports, visas, bank cards) - see the book "Optical Document Security", ed. by R. L. Van Renesse, Artech House, (1998). Holograms and other diffractive elements are mainly used, because their protective value is based on complexity of micron and submicron structures. Manufacturing is a complicated and expensive process whose final result is a master hologram - a single, unique prototype. To make protection commercially acceptable, the master hologram is copied and multiplied, resulting in a replica shim used for embossing into a plastic foil, which is then integrated into a document using a hot tool. The final result is a series of documents possessing exactly the same protective OVD. This is a significant drawback, because, if the OVD is counterfeited, a large number of fake documents can be manufactured.

As a result, there is ongoing research for a simple and affordable, document individualization method. This makes counterfeit much harder, because each and every document has to be copied individually, i.e. large scale production of false documents becomes impossible. However, the trivial individualization by simply printing numbers will not work, because it is too simple and affordable, if using modern printing technologies (e.g. laser printing). Therefore the individualization-bearing features must possess a significant amount of complexity together with strong, unrepeatable, individual properties. They have to be comparable in its uniqueness with biometric characteristics, such as: fingerprints, iris and retina pattern, but significantly more complex and miniscule. Currently used OVD security methods are not well suited for individualization (fingerprinting), as this will significantly increase the production prices.

Attempts to obtain "fingerprint" documents are based on the idea of physical one-way functions (alternatively called physically unclonable functions, as in C. Boehm, M. Hofer, "Physically unclonable functions in theory and practice", Springer, 2013) - which are physical devices simple to manufacture, yet extremely difficult to reverse engineer and copy. Random structures can be highly significant for document security, because they offer simple and cheap production, almost impossible re-origination and unique features. It was proposed to tag documents with randomly dispersed objects such as metal, fluorescent or optical fibers (van Renesse book, and references therein).

Natural fibrous structure of paper-based substrates was used (J. D. R. Buchanan, R. P. Cowburn, A-V.Jausovec, D. Petit, P. Seem, G. Xiong, D. Atkinson, K. Fenton, D. A. Allwood, M. T. Bryan, "'Fingerprinting' documents and packaging", Nature 436, (2005) 475). Laser beam was scattered from the paper surface and its statistics was observed and recorded. This however requires a large scale scanning of the document surface which is a slow process, and paper structure may be strongly affected by printing and everyday usage.

Yet another technique was described in R. Pappu, B. Recht, J. Taylor, N. Gershenfeld, "Physical One- Way Functions," Science 297, (2002) 2026 -2030, where mesoscopic scattering from disordered array of plastic spheres embedded in a transparent substrate was used to construct physical one-way function. The response of the system strongly depends on the illumination direction, again producing unique individual characteristics. The proposed method is limited by the physical requirements for the mesoscopic scattering, resulting in a 10 mm x 10 mm sized tag, with 2.5 mm thickness, which is unsuitable for the modern plastic card technology. Furthermore, the dimension of scattering particles is rather large - 500 - 800 μπι in diameter, with 100 μπι average spacing - resulting in a bulky system which can be reverse engineered by techniques like micro-tomography.

In addition to randomization techniques, artificial aperiodic or quasiperiodic markings are used for document security purposes, with the aim to further increase the complexity of protective features making them less susceptible to counterfeiting. A method is described in US20150302677, 2015, E. Mueller, "Non-periodic tiling document security element", in which a macroscopic, two-dimensional quasi-crystalline tiling pattern is printed on a document.

It is a common knowledge that certain natural characteristic of living creatures are essentially complex and hard to reproduce. This was first realized by Benjamin Franklin who used this for document protection (Farley Grubb, "Benjamin Franklin and the birth of the paper money economy", Essay based on March 30. 2006 lecture, published by Federal Reserve Bank of Philadelphia). He made casts of plant leaves (correctly recognizing the uniqueness of their venation) and used them to print the first dollar bills. Due to further technological advancements, Franklin's method became obsolete, and was replaced with different printing techniques, such as: intaglio, guilloche, watermark, holograms, etc.

WO 2007031077 (Al) 3/2007, C. Hamm-Dubischar, "Inorganic marking particles for characterizing products for proof of authenticity method for production and us thereof and DE10238506 Al, 3/2004, H. Rauhe, "Producing information-bearing micro-particulate mixtures involves defining code that can be implemented using natural or subsequently applied particle characteristics selected from e.g. morphology", disclose an idea for document protection which uses natural complexity of inorganic shells of aquatic organism (like diatoms and radiolarians) according to characteristics of their surfaces. The practicing method is, however, not disclosed. Another problem is that the optical effects are not very pronounced, and the complexity can be observed only at the sub-wavelength levels, using electron microscopy. Technique for estimating the degree of complexity was not described, either. Variation among the specimens of the same species is rather small. In that respect, the method can be used only for the forensic level of document authentication.

Recently, there was a significant amount of research aimed at using the principles of optics in nature for document protection (J. Sun, B. Bhushanand J. Tong, "Structural coloration in nature", RSC Adv. 3, (2013) 14862-14889, and B. Yoon, J. Lee, I. S. Park, S. Jeon, J. Lee, J-

M. Kim, "Recent functional material based approaches to prevent and detect counterfeiting", J.

Mater. Chem. C 1, (2013) 2388 - 2403). Variability of biological structures was also observed

(L. P. Biro and J-P.Vigneron, "Photonic nanoarchitectures in butterflies and beetles: valuable sources for bioinspiration", Laser Photonics Rev.5, (2011) 27-51). Biotemplating was used to manufacture butterfly scale-like structures using metals (S.Sotiropoulou, Y. Sierra-Sastre, S. S.

Mark, and C. A. Batt, "Biotemplated Nanostructured Materials", Chem. Mater. 20, (2008) 821-

834).

In addition to utilization of the unmodified biological particles, it is possible to use modified ones. The modification of the biological particles enable achievements of different criteria in document security such as: improved security, facilitated forensic, more difficult counterfeiting, self advertising, logo imprint, aesthetics, etc. Biological particles of microscopic sizes can be modified in various manners in order to meet aforementioned criteria. Precise cutting the biological specimens at microscopic level using a laser beam is described in US 8535876 B2 (2013), Wesner, "Laser micro dissection method and device for laser micro dissection". It is possible to use other, for instance mechanical methods for micro cutting and shaping, but laser beams are in principle more convenient and especially ultrafast laser pulses due to precise cutting lines and lack of melted parts of the material. The biological particles can be modified in other manners except cutting, like photo damage or permanent photo bleaching. Since chitin, the main building block of the arthropodes, exhibits strong fluorescence when irradiated with blue or soft UV light, it is possible to bleach particles made of chitin. (M. Rabasovic et al. "Nonlinear microscopy of chitin and chitinous structures: a case study of two cave-dwelling insects",/. Biomed. Opt. 20, (2015) 016010).

The randomized systems described above must be machine-inspected, based on radiation scattering with consequent optical or microwave detection (in the case of metal inclusions). Recorded pattern is encrypted and stored in a central repository or on the document itself. Public key encryption method is used, as described in the report: Counterfeit deterrent features for the next generation currency design", Committee on Next-Generation Currency Design, National Materials Advisory Board, Commission on Engineering and Technical Systems, National Research Council, Publication NMAB-472, (1993), Section: Random Pattern/Encryption Counterfeit-Deterrence Concept, pg. 74 - 75, and Appendix E: "Methods for authentication of unique random patterns", pg. 117 - 119. The technique is based on two keys: a secret one, used for encryption, and a public one, used for decryption.

All the methods use a complexity of natural structures, but their variability remained completely unused in the context of document protection. Document variability was rather attained by randomly dispersing particle- or thread-like entities across the document. Summary of the Invention

The problem solved by the present invention is individualization of security tags. This is done by permanently attaching an arrangement of biological particles with pronounced individuality that are modified in the manner of cutting, permanent bleaching, scribing and/or stacking. The invention is directed to a security tag, comprising: a transparent substrate; an arrangement of processed biological particles in a specific pattern which is attached to the substrate; and a transparent superstrate, having a recess, and adhering to the substrate and enclosing the biological particles.

Preferably, the biological particles are obtained from dead, non-decomposable, tissues.

More preferably, the biological particles are selected from scales, hairs or bristles ofLepidoptera, Trichoptera, Coleoptera and Aranea or wings of Hymenoptera. In a preferred embodiment of the invention, the processing of the biological particles is done by cutting them in predefined shapes, preferably by using a laser beam.

The arrangement of processed biological particles may preferably be further processed.

In one embodiment of the present invention, the further processing of the arrangement of processed biological particles is done by permanently bleaching out the natural autofluorescence of the biological particles in a predefined pattern, bearing personal or other information, using actinic radiation. The actinic radiation may be laser or non-laser radiation.

In another embodiment of the invention, the further processing of the arrangement of processed biological particles is done by artificially dyeing the biological particles with fluorescent dyes, and permanently bleaching out the artificial fluorescence of the dyed particles in a predefined pattern bearing personal or other information, using actinic radiation. The actinic radiation may again be laser or non-laser radiation.

More preferably, the arrangement of processed biological particles is defined according to a predetermined periodic, quasi-periodic, aperiodic or irregular pattern. In one specific embodiment of the invention, the biological particles are cut in a gear shape, and positioned on cylindrically cut particles in a shaft shape, and the cylindrically shaped particles are strongly attached to the tag surface using a strong adhesive, while the gear shaped biological particles are not adhesively bonded to the tag surface, thus producing a freely moveable, interlocked, micromechanical iridescent system. In one preferred embodiment, the arrangement of processed biological particles is defined by a bar-code pattern.

It is also preferred that the arrangement of processed biological particles is inscribed with additional information by laser ablation.

In one embodiment of the present invention, the transparent substrate comprises a transparent adhesive layer on its lower surface, which preferably is of the pressure-sensitive or hot printing type. In a preferred embodiment of the invention, the biological particles possess a grating-like diffracting structure.

Preferably, the inscribed information bears personal data, such as silhouette, fingerprint, retinal pattern image and/or numerical information such as a bar- or QR-code. The invention preferably envisages that the arrangement of processed biological particles is inscribed with alternating bleached, ablated or untreated spots, in arbitrary order forming the numbers coded in ternary system.

Furthermore, the invention is directed to the use of a security tag according to the invention for identification and authentication of goods, articles and documents. The invention is also directed to a method of manufacturing a security tag according to a preferred embodiment, wherein a laser beam with average intensity 0.002 - 2 kW/cm at the focal area of the laser beam is used to bleach the biological particles. Finally, the invention is directed to a method of manufacturing a security tag according to another preferred embodiment, wherein ultra-short laser pulses of a duration of less than lps and an average intensity in the range of 0.2 - 1000 kW/cm" at the focal area of the laser beam are used to cut the biological particles.

There are several criteria which must be simultaneously fulfilled in order to give a unique fingerprint, usable for document protection purposes. Biological particles are selected according to variability of optical effects (interference, diffraction, fluorescence, scattering), internal complexity of their structure, fragility, capability of being easily and reproducibly processed by a laser beam, non-degradability and thinness.

A resulting tag containing biological nano- and microstructures is a unique and unrepeatable protective device. Organisms and tissues are chosen such that the observed optical effects are strongly localized, variable, and individual and the result of interference, diffraction, fluorescence and scattering from complicated three-dimensional structures. Additionally, tissues are chosen to be durable, with permanent optical properties and capable of being transferred and processed before, during or after attachment to the substrate. Biological particles are permanently attached to the substrate, usually by using a strong adhesive. As a result, the tag cannot be disassembled without permanently destructing its optical properties.

Brief Description of Drawings Fig. 1 : Optical image of an individual butterfly scale, where the strong, local, variability of iridescence can be observed.

Fig. 2: Scanning electron microscope image of the butterfly scale, where the complexity of its internal structure can be seen.

Fig. 3: A natural biological particle is cut into predefined shapes, which are further arranged in tiling (e.g. jigsaw and Penrose type) or non-repeating (e.g. tangram type) patterns.

Fig. 4: A security tag presented in two orthogonal projections. Fig. 5: A security tag with an array of patches where precut biological particles are arranged and attached.

Fig. 6: A security tag with an array of patches where precut biological particles are arranged, attached, and, overtly and covertly, inscribed.

Fig. 7: A security tag with an arrangement of precut biological particles, which contain bits of information inscribed as bleached, ablated and untreated areas.

Fig. 8: A security tag with an arrangement of precut biological particles whose iridescence depends on the orientation of the light sources.

Fig. 9: A security tag with an arrangement of precut biological particles positioned in a rectangular grid, defining a bar-code.

Fig. 10: A security tag with biological particles precut in a gear shape and attached to the surface, such that a moveable gear system is constructied.

Detailed Description of the Invention

In cooperation with the attached drawings, the technical contents and detailed embodiments of the present invention are described hereinafter, however, not limiting its scope of protection which is exclusively defined by the claims. Any equivalent variation and modification made according to the appended claims is to be covered by their scope of protection.

The tag manufacturing process starts with selecting appropriate biological particles according to several criteria, described in the following text.

The first criterion for biological particle selection is according to variability of optical properties across their surface (near-field) or in the far-field of the scattered radiation. Detected optical properties include optical field amplitude and phase, field vorticity, reflection and transmission spectral distribution, overall biological particle shape, moire pattern, polarization pattern, iridescence, diffraction, and fluorescence. The second selection criterion is the underlying complexity of biological particle structure, which has to span the range from nanometer to micron-size features, intricately distributed in three-dimensions. The third criterion is their fragility, necessary for tamper sensitivity. The fourth criterion is the non-degradability of the structure, at least within the validity period of the document. The fifth criterion is the thinness of the structures such that they can be easily used for security tag production or integrated within existing OVDs, whose thickness is of the order of several tens of microns. The selection process requires fulfillment of all five criteria.

Preferred biological particles, in the literature named scales, are those which can be found in or on the cuticle of various insects. There is a general ground-plan of theseparticles, with the details significantly depending on the species. They are self-contained (Fig. 1), plate-like or cylindrical, having a wall of submicron thickness, which encloses the internal volume. Inside the particle, a number of features may exist, such as nano-pillars, photonic crystals, fluorescent nano-particles. One or both external surfaces are patterned with the grating-like ridges and cross- ridges (Fig. 2). Ridges have a lamellar structure, similar to the Bragg grating. The main constituent is chitin, a biological polysaccharide insoluble in water and many other solvents. They are permanent remnants of individual cells, and may endure without changing their optical properties for long periods - it is known that dried insects like butterflies may survive for decades in entomological collections. Iridescence, diffraction pattern or fluorescence of individual particles may strongly vary across the surface (of the order of 50 x 150 μπι ), as can be seen in Fig. 1. Thickness is of the order of few microns, resulting in fragility of the whole structure, which is stable enough to be transferred to the substrate during security tag production or transferred and adhered to the existing OVD's substrate.

More specifically, preferred biological particles are scales, hairs or bristles of Lepidoptera, Trichoptera, Coleoptera or Araneae. Preferred Lepidoptera species are those possessing silver spots or patches, but are not limited to them. Examples of species are: Issoria lathonia, Argyrophorus argenteus, Dione moneta, Dione juno, Agraulis vanillae. Other preferred Lepidoptera species are selected amongst Microlepidoptera, Rhopalocera (butterflies) or Heterocera (moths) exhibiting structural coloration, such as: Diachrysia chrysitis, Macdunnoughia confusa, Autographa gamma, Jordanita globulariae, Callophrys rubi, Apatura iris, Apatura ilia, Aglais io. Preferred Coleoptera species are (but not limited to them): Hoplia coeruela, Pseudomyagrus waterhousei, Lamprocyphus augustus, Hypera diversipunctata, Prosopocera lactator, Cyphus hancocki, Entimus imperialis, Sphingnotus mirabilis, Hoplia argentea, some species of Curculionidae and Collembolae families. Preferred Trichoptera species, but not limited to them, are: Pseudoleptocerus chirindensis, Phylloicus abdominalis, Nectopsyche punctata, Banyallarga vicaria, Hesperophylax designates, Polycentropus flavomaculatus, Mystacides azurea, Mystacides longicornis, Anthripsodes albifrons, Limnephilus binotatus. Preferred Araneae species are those possessing scales on their cuticle, but not limited to them, such as: Maratus volans, Maratus splendens, Phidippus audax, Pamphobeteus antinuous, Cyriopagopus lividum.

The tag manufacturing proceeds with precutting natural biological particles, described above, into required shapes. Preferably, referring to Fig. 3, an individual, unmodified, Lepidoptera scale 1 is removed from the wing and cut into a number of even smaller, shaped particles 2. As an alternative, hairs, scales or bristles of Coleoptera, Araneae and Trichoptera are used in the same manner. As another alternative, a Hymenoptera wing is precut into a number of even smaller, shaped, particles.

Particles are precut to enable tiled or irregular arrangements. Preferred tiling arrangements are periodic (e.g. jigsaw pattern 3 in Fig. 3) and quasi-periodic (e.g. Penrose tiling pattern 4 in Fig. 3), see the book B. Griinbaum, G. C. Shephard, Tilings and patterns, W.H. Freeman, 1990. Preferred non-tiled arrangements of precut particles are those which are not capable of tessellating (covering without gaps) a surface (e.g. tangram pattern 5 in Fig. 3).

The precut particles are transferred and attached to the surface of the tag substrate in a stack or in a predefined arrangement using micromanipulation techniques (as described in "Robotic microassembly", Ed. By M. Gauthier and S. Regnier, (2010) Johh Willey and Sons).

The particles are cut in a predefined pattern by a laser beam. Preferably, a beam from an ultrafast laser is introduced in a system with a computer-controlled galvanometer-mirror scanner, which is used to angularly deflect the beam according to programmed trajectory. The beam is then expanded and focused to the tag with biological particles, using a microscope objective. The laser wavelength, scanning speed and power are chosen such that cutting or engraving or bleaching is enabled. The obtained tag can be used independently, or it can be permanently attached to an existing OVD on the document. Only a subset of attached particles might be used for authentication purposes, while the rest is there as a distraction, which makes counterfeit harder, as a counterfeiter would not know which particles are used for authentication. Biological particles which possess different optical properties on their front and rear side are used to produce security features which can be read from both sides in perfect alignment (see-through register).

Reference is made to Fig. 4 which presents two orthogonal views of one embodiment of the security tag of the present invention. It is composed of a substrate 6, having an adhesive layer 7 at its lower surface, which can be activated either by heat, light or pressure in order to integrate the tag with the article, good or document. The upper surface of the substrate 6 comprises a small patch of adhesive 8, whose surface is just large enough to receive precut biological particles 9. They are permanently attached onto the adhesive patch 8 in a predefined pattern (periodic, quasiperiodic, aperiodic or irregular).

The attached biological particles 9 are covered with a superstrate 10, having a recess 11 large enough to contain and enclose the attached biological particles 9, without touching their upper surfaces. The lower surface of the superstrate 10 is covered with a transparent layer of heat or pressure activated adhesive 12, such that the recess 11 is left without adhesive layer. Superstrate 10 and substrate 6 are attached to each other and sealed by an adhesive layer 12, such that they enclose the attached biological particles 9.

Additional marks 13, 14 and 15, whose dimensions are smaller than 200 μπι, may be incorporated into the substrate 6. The marks are used as reference points and attached biological particles are put in pre-defined positions, with respect to said reference points.

In another embodiment (Fig. 5), the security tag of the present invention is designed and manufactured to have an unspecified number of small patches of adhesive 16, 17, 18, 19 and 20, whose surface is just large enough to each receive precut biological particles 9 arranged in a pattern. The patches are placed in an orderly manner, corresponding to certain symmetry, as in Fig. 5. The width and height of the patches is preferably within the range of 150 μπι - 1000 μπι. Precut biological particles of Lepidoptera, Trichoptera, Coleoptera, Araneae or Hymenoptera are attached to each patch in a predefined arrangement. The patches are either filled with precut biological particles from the single species, or from precut biological particles from several different species. The substrate with precut and arranged biological particles is covered with a transparent superstrate having recesses exactly matching the positions of the patches. A thin layer of a transparent adhesive is placed on the bottom side of a cover, without covering the recesses. This layer is used to seal the precut biological particles between the substrate and the superstrate.

In a further embodiment, depicted in Fig. 6, a security tag is disclosed where the natural autofluorescence of precut and arranged biological particles 9 is permanently bleached out in a predefined pattern. In this way the precut and arranged biological particles are covertly inscribed with a secret code or personal information (e.g. text, numbers, image, barcode). The pattern is, for example, inscribed by a scanning sub-picosecond laser beam that induces two-photon absorption at the focal point. The laser wavelength is in the range 650-1050 nm, and its intensity is in the range 0.002 - 2 kW/cm", at the focal area of the laser beam. Exact value of the intensity depends on the scanning speed and the size of the focal spot, too. The laser beam is focused using a high numerical aperture microscopic objective and scanned using galvo-scanning mirrors, as previously described.

In an alternative embodiment the precut and arranged biological particles are dyed with fluorescent dye prior to the inscription. Information can be inscribed before or after the encapsulation of the precut and arranged biological particles on the security tag.

In yet another embodiment of the present invention, portions of the precut and arranged biological particles are ablated in a predefined pattern, as illustrated in Fig. 6. In this way the scales are overtly inscribed with a secret code or personal information (e.g. text, numbers, image, barcode). The pattern is, for example, inscribed by a scanning sub-picosecond laser beam that ablates material in the focal point. The laser wavelength is in the range 650-1050 nm and the intensity is in the range 0.2 -1000 kW/cm . The laser beam is focused using a high numerical aperture microscopic objective and scanned using galvo-scanning mirrors, as previously described. In yet another embodiment of the present invention (depicted in Fig. 7), a tag contains precut and arranged biological particles 21 which are inscribed with, either bleached 22, ablated 23 or untreated 24 spots, in arbitrary order forming the numbers coded in the ternary system. This enables more data to be stored on the same area compared to the binary system. In a further embodiment, biological particles, which possess diffraction grating-like structures, are selected. As a consequence, their iridescence depends on the illumination direction, with respect to the grating orientation. They are precut by taking care of mutual orientation between the cut shape and the grating. After arranging and attaching precut biological particles on the tag surface, iridescence pattern strongly depends on the illumination direction, as shown in Fig. 8. If an arrangement of precut particles (e.g. tangram as in Fig. 8 A) is illuminated from the lightsource 25, only particles a, b, c reflect light iridescently. If the same arrangement of precut particles (Fig. 8B) is illuminated from the light source 26, only precut particle d reflects light iridescently. Finally, If the same arrangement of precut particles (Fig. 8C) is illuminated from the lightsource 27, only particles e,f, g reflect light iridescently. In yet another embodiment depicted in Fig. 9, precut biological particles are arranged and attached in a regular, rectangular grid within the adhesive patch 28 of a tag. Grid occupancy defines a binary encoding of information, where any occupied position, such as 29 in Fig. 9, designates binary 1, and any unoccupied position, such as 30 in Fig. 9, defines binary 0. In that sense, they represent a one- or two-dimensional iridescent bar-code. In the next embodiment depicted in Fig. 10, iridescent biological particles are cut in a gear shape 31, 32. Shafts 33 and 34 (which can be made from biological particles, too, but can also be made from different material) are firmly attached to the tag surface 35 using, locally applied adhesive. Gears 31 and 32 are put on the shafts 33 and 34, respectively, without using any adhesive layer on the tag surface 35, and thus arranged in an interlocked position as to produce a micromechanical moveable system.

Claims

1. A security tag, comprising: a transparent substrate (6); an arrangement of processed biological particles (9) in a specific pattern which is attached to the substrate (6); and a transparent superstate (10), having a recess (11), and adhering to the substrate (6) and enclosing the biological particles (9).

2. The security tag according to claim 1 , wherein the biological particles (9) are obtained from dead, non-decomposable, tissues.

3. The security tag according to claim 2, wherein the biological particles (9) are selected from scales, hairs or bristles of Lepidoptera, Trichoptera, Coleoptera and Aranea or wings of Hymenoptera.

4. The security tag according to any of the preceding claims, wherein the processing of the biological particles (9) is done by cutting them in predefined shapes.

5. The security tag according to claim 4, wherein the cutting is done by using a laser beam.

6. The security tag according to any of the preceding claims, wherein the arrangement of processed biological particles (9) is further processed.

7. The security tag according to claim 6, wherein the further processing of the arrangement of processed biological particles (9) is done by permanently bleaching out the natural autofluorescence of the biological particles (9) in a predefined pattern, bearing personal or other information, using actinic radiation.

8. The security tag according to claim 6, wherein the further processing of the arrangement of processed biological particles (9) is done by artificially dyeing the biological particles (9) with fluorescent dyes, and permanently bleaching out the artificial fluorescence of the dyed particles (9), in a predefined pattern bearing personal or other information, using actinic radiation.

9. The security tag according to any of the preceding claims, where the arrangement of processed biological particles (9) is defined according to a predetermined periodic, quasi- periodic, aperiodic or irregular pattern.

10. The security tag according to claims 4 to 9, wherein the biological particles (9) are cut in a gear shape (31,32), and positioned on cylindrically cut particles in a shaft shape (33,34), and the cylindrically shaped particles (33,34) are strongly attached to the tag surface (35) using a strong adhesive, while the gear shaped biological particles (31, 32) are not adhesively bonded to the tag surface, thus producing a freely moveable, interlocked, micromechanical iridescent system.

11. The security tag according to any of the preceding claims, wherein the arrangement of processed biological particles (9) is defined by a bar-code pattern.

12. The security tag according to any of the preceding claims, wherein the arrangement of processed biological particles (9) is inscribed with additional information by laser ablation.

13. The security tag according to any of the preceding claims, wherein the transparent substrate (6) comprises a transparent adhesive layer (7) on its lower surface.

14. The security tag according to claim 13, wherein the transparent adhesive layer (7) is of the pressure-sensitive, hot printing or light activating type.

15. The security tag according to any of the preceding claims, wherein the biological particles (9) possess a grating-like diffracting structure.

16. The security tag according to any of claims 7 to 10, or 12 wherein the, covertly or overtly inscribed, information bears personal data, such as silhouette, fingerprint, retinal pattern image.

17. The security tag according to any of claims 7 to 10, or 12 wherein the, covertly or overtly, inscribed information bears numerical information such as a bar- or QR-code.

18. The security tag according to any of claims 7 to 10, or 12 wherein the arrangement of processed biological particles (9) is inscribed with alternating bleached, ablated or untreated spots, in arbitrary order forming the numbers coded in ternary system.

19. Use of a security tag according to any of the preceding claims for identification and authentication of goods, articles and documents.

20. A method of manufacturing a security tag according to claim 7 or 8, wherein a laser beam with average intensity 0.002 - 2 kW/cm at the focal area of the laser beam is used to bleach the biological particles.

21. A method of manufacturing a security tag according to claim 5, wherein ultra-short laser pulses of a duration of less than lps and an average intensity in the range of 0.2 - 1000 kW/cm at the focal area of the laser beam are used to cut the biological particles.