Optically readable physical unclonable function

Abstract

A method of making an optically readable PDF coating composition is provided that includes increasing the entropy of the coating composition by adding an optically readable material and an optional solvent to at least two portions of the coating composition and then combining the portions of the coating composition.

Description

Technical Field

[0001] The present invention generally relates to an optically readable Physical Unclonable Function (PUF), a method of making an optically readable PUF, and an article comprising an optically readable PUF. Background Art

[0002] It is often necessary to prove or deny the authenticity of an object or similar object. This may be necessary for security purposes, for example, to allow or prevent access to certain functions associated with the object, or simply to allow the user or consumer of the object to be sure that they are using an authentic object. It is understandable that such authenticity testing has applications in the fields of anti-counterfeiting, security, etc.

[0003] In order to be able to prove that an object is a genuine object, or in other words, to verify the authenticity of an object, the object may be provided with a unique identifier in one form or another. "Unique" does not necessarily mean that it is impossible for another object to have the same identifier, but that it is statistically extremely unlikely, or in other words, that the identifier is difficult to discover accidentally by guessing or simple trial and error. Exactly the same "uniqueness" may also be used for other purposes, such as highly targeted marketing or data collection on the object or the user or consumer of the object.

[0004] For example, a unique identifier may take the form of or be derived from a physically (sometimes called physically) unclonable function (PUF). This may be in the form of a device or other component whose characteristics depend on slight variations in construction or manufacturing or the like, but which can still be used to provide a unique identifier. For example, in a large array of memory cells, a certain number of memory cells may be defective, and the number or arrangement of defective cells will vary for different arrays produced. So this is a simple example of a unique identifier. Another example might be, for example, the capacitance or resistance of an electronic component, based on the thickness of the layers within the component or the extent of those layers, etc. Due to manufacturing tolerances, each component is likely to have a slightly different structure and therefore slightly different and unique electrical characteristics.

[0005] The unique identifier need not necessarily be based on electrical principles. For example, the physical unclonable function may be detected or otherwise visually challenged in order to determine the unique identifier. For example, providing one or more optical emitters on the object may, as described above, produce a unique overall emission spectrum or pattern, again providing a readable unique identifier.

[0006] Traditionally, the generation of unique identifiers and / or the related use of physical unclonable functions are based on macroscopic effects. However, it has recently been proposed to merge quantum mechanical effects into the generation of unique identifiers. In these newer examples, for example, electronic components (e.g., resonant tunneling diodes) that exhibit quantum mechanical constraints can be used as physical unclonable functions based on quantum mechanics. The electrical properties of such devices or structures and the unique identifiers in this manner are based on the principles of quantum mechanics. Similarly, optically based physical unclonable functions may be based on the emission spectra of quantum dots, two-dimensional materials, or the like located on an object. In both cases, it may be extremely difficult or even impossible to physically replicate security elements (e.g., as or including physical unclonable functions) based on quantum mechanical effects. So much so that the unique identifier provided by such an element may not be circumvented, and certainly not circumvented within any practical time frame. Summary of the invention

[0007] An exemplary object or exemplary embodiment of the present invention is to at least partially overcome or circumvent one or more disadvantages of the prior art (whether pointed out herein or elsewhere), or at least provide a viable alternative.

[0008] According to the present invention, there is provided a product and a method as described in the accompanying claims. Further features of the invention will be apparent from the dependent claims and the following description.

[0009] According to a first aspect of the present invention, there is provided a method of making an optically readable PUF coating composition, the method comprising increasing the entropy of the coating composition by adding a first optically readable material to the coating composition.

[0010] By "optically readable PUF coating composition" is meant a composition that, when applied to a substrate, provides an optically readable PUF (i.e., a physically unclonable function). An optically readable PUF can be used to provide an optically verifiable unique identifier. The properties of an optically readable PUF may depend on subtle variations in structure or manufacturing or the like.

[0011] By "entropy" is meant the degree of randomness or non-uniformity of the distribution of components in a coating composition. Entropy can be measured by the uniformity of an optically readable PUF prepared from an optically readable PUF coating composition, as described in the Examples.

[0012] The method of the first aspect advantageously provides an optically readable PUF coating composition comprising a random, non-uniform distribution of optically readable material. This can provide an optically readable PUF with improved properties, such as uniqueness and readability, while maintaining the coating properties of the coating composition. The method of the first aspect is surprising because it is generally desirable to have a coating composition with minimal entropy.

[0013] The method of the first aspect may also allow the production of optically readable PUFs that do not necessarily rely on quantum mechanical effects. Thus, optically readable PUF coating compositions may be produced more cheaply or more easily using widely available starting materials.

[0014] Prior to the addition of the optically readable material, the coating composition would not properly provide an optically readable PUF when applied to a substrate. For example, the coating composition may be free or substantially free of the first optically readable material. By "substantially free," we mean that the coating composition includes no more than a trace amount of the first optically readable material.

[0015] The coating composition may include a solvent. The solvent may include a polar solvent and / or a non-polar solvent. Preferably, the solvent includes a polar solvent. The solvent may include an organic solvent and / or an inorganic solvent. The solvent may include a mixture of an organic solvent and an inorganic solvent (such as water). Preferably, the solvent includes an organic solvent. The organic solvent suitably includes a polar organic compound with 6 or less carbon atoms. The organic solvent may include an alcohol and / or a ketone. Suitable examples of organic solvents include ethanol, propanol, isopropanol and acetone. Ethanol is preferred.

[0016] The coating composition suitably includes a polymer. The polymer can act as a binder to allow the coating composition and any other ingredients in the composition to adhere to the substrate and form a coating. The polymer can be a liquid. Alternatively, in embodiments where the coating composition includes a solvent, the polymer can be dissolved in the solvent.

[0017] The coating composition can be curable (e.g., when the coating composition includes a liquid polymer) or air-dryable (e.g., when the coating composition includes a polymer dissolved in a solvent). The coating composition can be heat-curable, UV-curable, air-curable, or chemically cured. So-called "chemical curing" refers to curing the coating composition by mixing a curing agent into the composition. Suitably, the curing agent is mixed into the coating composition before the composition is applied to the substrate. Preferably, the coating composition is UV-curable.

[0018] The coating composition is suitably a paint. The so-called "paint" refers to a coating composition that forms a transparent coating. The use of paint as a coating composition makes it easier to read the optically readable PUF obtained when the optically readable PUF coating composition provided by the method of the first aspect is applied to a substrate. The first optically readable material is advantageously more visible in the transparent coating.

[0019] The paint may be curable or air-dryable. The paint may be heat-curable, UV-curable, air-curable or chemically curable. Preferably, the paint is UV-curable.

[0020] The first optically readable material may include any suitable material that can be detected optically. The first optically readable material may include quantum dots, quantum wires, thin sheets or layers of substantially two-dimensional materials, metal nanoparticles, colored compounds and / or fluorescent compounds. Preferably, the first optically readable material includes quantum dots, quantum wires, thin sheets or layers of substantially two-dimensional materials, metal nanoparticles and / or fluorescent compounds. The first optically readable material may emit electromagnetic radiation of a single wavelength, or the first optically readable material may emit electromagnetic radiation of different wavelengths, for example, electromagnetic radiation of wavelengths corresponding to changes in the band gap of the first optically readable material. Therefore, the first optically readable material may be an emitter of electromagnetic radiation, or in other words, may be a material that is configured to or is generally capable of emitting electromagnetic radiation when excited (for example, by exciting electromagnetic radiation).

[0021] In some embodiments, the first optically readable material comprises quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, and / or metallic nanoparticles. The first optically readable material may comprise a plurality of quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, and / or metallic nanoparticles.

[0022] By "substantially two-dimensional material" is meant a material having a thickness of a few nanometers or less, for example, such that the movement of electrons in and out of the two-dimensional plane is governed by quantum mechanical effects.

[0023] In some embodiments, the first optically readable material comprises a colored compound. By "colored compound" is meant a compound that absorbs electromagnetic radiation in the visible spectrum, for example, a compound having a wavelength from 400 nm to 700 nm.

[0024] In some embodiments, the first optically readable material comprises a fluorescent compound.A fluorescent compound is an emitter of electromagnetic radiation, or in other words, a compound capable of emitting electromagnetic radiation when excited (eg, by exciting electromagnetic radiation).

[0025] Fluorescent compounds may include small molecules. Fluorescent compounds suitably include polyunsaturated compounds, for example, polyaromatic compounds. Suitable examples of fluorescent compounds include rhodamine dyes, cyanine dyes, phthalocyanine dyes, porphyrin dyes and quinacridones. Rhodamine dyes and cyanine dyes are preferred. Rhodamine dyes may be selected from rhodamine 6G, rhodamine 123 and / or rhodamine B. Cyanine dyes may be selected from Cy2, Cy3, Cy3.5, Cy5, C5.5, Cy7 and / or Cy7.5.

[0026] Based on the total volume of the optically readable PUF coating composition, the first optically readable material can be added to the coating composition in an amount of from 0.1 mg / mL to 15 mg / mL (such as from 0.5 mg / mL to 10 mg / mL, such as from 1 mg / mL to 5 mg / mL). Based on the total weight of the optically readable PUF coating composition, the first optically readable material can be added to the coating composition in an amount of from 0.01 wt% to 1.5 wt% (such as from 0.05 wt% to 1.0 wt%, such as 0.08 wt% to 0.4 wt%).

[0027] Suitably, the first optically readable material is poorly soluble or insoluble in the coating composition. At a temperature of 20° C. and a pressure of 100 kPa, the first optically readable material may have a solubility in the coating composition of less than 100 mg / mL, such as less than 50 mg / mL, such as less than 10 mg / mL, for example less than 1 mg / mL. Advantageously, when the first optically readable material is poorly soluble or insoluble in the coating composition, adding the first optically readable material to the coating composition may result in aggregation or agglomeration of the first optically readable material.

[0028] The method of the first aspect suitably comprises dispersing the first optically readable material non-uniformly in the coating composition. The resulting coating composition suitably comprises a non-uniformly distributed first optically readable material. For example, the resulting coating composition may comprise clusters or aggregates of the first optically readable material. The first optically readable material may be mixed into the coating composition, but not to the extent that the first optically readable material is uniformly distributed.

[0029] The method of the first aspect may include adding the first optically readable material to a coating composition that does not contain a solvent. In other words, the first optically readable material is not mixed with a solvent before being added to the coating composition. This helps ensure that the first optically readable material is non-uniformly distributed in the coating composition.

[0030] The method of the first aspect may further comprise mixing the second optically readable material with a solvent to form a mixture, and adding the mixture to the coating composition.

[0031] The second optically readable material may comprise any suitable material that can be detected optically. The second optically readable material may comprise quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, metal nanoparticles, colored compounds and / or fluorescent compounds. Preferably, the second optically readable material comprises quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, metal nanoparticles and / or fluorescent compounds. The second optically readable material may emit radiation of a single wavelength, or the second optically readable material may emit radiation of different wavelengths, for example, radiation of wavelengths corresponding to a change in the band gap of the second optically readable material. Thus, the second optically readable material may be an emitter of electromagnetic radiation, or in other words, may be a material that is configured to or is generally capable of emitting electromagnetic radiation when excited (e.g., by exciting electromagnetic radiation).

[0032] In some embodiments, the second optically readable material comprises quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, and / or metallic nanoparticles. The second optically readable material may comprise a plurality of quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, and / or metallic nanoparticles.

[0033] In some embodiments, the second optically readable material comprises a colored compound.

[0034] In some embodiments, the second optically readable material comprises a fluorescent compound.A fluorescent compound is an emitter of electromagnetic radiation, or in other words, a compound that is capable of emitting electromagnetic radiation when excited (eg, by exciting electromagnetic radiation).

[0035] Fluorescent compounds may include small molecules. Fluorescent compounds suitably include polyunsaturated compounds, such as polyaromatic compounds. Suitable examples of fluorescent compounds include rhodamine dyes, cyanine dyes, phthalocyanine dyes, porphyrin dyes and quinacridones. Rhodamine dyes and cyanine dyes are preferred. Rhodamine dyes may be selected from rhodamine 6G, rhodamine 123 and / or rhodamine B. Cyanine dyes may be selected from Cy2, Cy3, Cy3.5, Cy5, C5.5, Cy7 and / or Cy7.5.

[0036] The first optically readable material and the second optically readable material may be the same or different. Preferably, the first optically readable material is different from the second optically readable material. When the first optically readable material and the second optically readable material are the same, in the optically readable PUF coating composition, the first optically readable material and the second optically readable material have appropriate optical distinction. For example, differences in the chemical environment in which the optically readable material is located (e.g., the medium in which the optically readable material is dispersed) can result in differences in emission.

[0037] Suitably, the first optically readable material and / or the second optically readable material comprises quantum dots, quantum wires, sheets or layers of substantially two-dimensional material, metallic nanoparticles and / or fluorescent compounds.

[0038] Preferably, the first optically readable material and / or the second optically readable material comprises a fluorescent compound. The fluorescent compound may comprise a small molecule. The fluorescent compound suitably comprises a polyunsaturated compound, such as a polyaromatic compound. Suitable examples of fluorescent compounds include rhodamine dyes, cyanine dyes, phthalocyanine dyes, porphyrin dyes and quinacridones. Rhodamine dyes and cyanine dyes are preferred. Rhodamine dyes may be selected from rhodamine 6G, rhodamine 123 and / or rhodamine B. Cyanine dyes may be selected from Cy2, Cy3, Cy3.5, Cy5, C5.5, Cy7 and / or Cy7.5.

[0039] Suitably, the second optically readable material is poorly soluble or insoluble in the coating composition. At a temperature of 20° C. and a pressure of 100 kPa, the second optically readable material may have a solubility in the coating composition of less than 100 mg / mL, such as less than 50 mg / mL, such as less than 10 mg / mL, for example less than 1 mg / mL. Advantageously, the second optically readable material is added to the solvent before being added to the coating composition, so that the second optically readable material is evenly distributed in the coating composition.

[0040] The solvent mixed with the second optically readable material may include a polar solvent and / or a non-polar solvent. Preferably, the solvent includes a polar solvent. The solvent may include an organic solvent and / or an inorganic solvent. The solvent may include a mixture of an organic solvent and an inorganic solvent (such as water). Preferably, the solvent includes an organic solvent. The organic solvent suitably includes a polar organic compound having 6 or less carbon atoms. The organic solvent may include an alcohol and / or a ketone. Suitable examples of organic solvents include ethanol, propanol, isopropanol and acetone. Ethanol is preferred.

[0041] The second optically readable material is soluble in the solvent. At a temperature of 20° C. and a pressure of 100 kPa, the second optically readable material may have a solubility of at least 1 mg / mL in the solvent, such as at least 10 mg / mL, such as at least 50 mg / mL, for example at least 100 mg / mL. The mixture of the second optically readable material and the solvent is suitably a solution.

[0042] The second optically readable material and the solvent may be homogeneously mixed. The second optically readable material homogeneously mixed in the solvent may advantageously provide a homogeneous background emission for the optically readable PUF coating composition.

[0043] The second optically readable material may be added to the solvent in an amount from 10 mg / mL to 500 mg / mL, such as from 50 mg / mL to 200 mg / mL, such as from 80 mg / mL to 150 mg / mL, based on the total volume of the mixture.

[0044] The method of the first aspect may comprise adding a third optically readable material to a mixture of the second optically readable material and a solvent, and adding the mixture to the coating composition.

[0045] The third optically readable material may comprise any suitable material that can be detected optically. The third optically readable material may comprise quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, metal nanoparticles, colored compounds and / or fluorescent compounds. Preferably, the third optically readable material comprises quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, metal nanoparticles and / or fluorescent compounds. The third optically readable material may emit radiation of a single wavelength, or the third optically readable material may emit radiation of different wavelengths, for example, radiation of wavelengths corresponding to a change in the band gap of the third optically readable material. Thus, the third optically readable material may be an emitter of electromagnetic radiation, or in other words, may be a material that is configured to or is generally capable of emitting electromagnetic radiation when excited (e.g., by exciting electromagnetic radiation).

[0046] In some embodiments, the third optically readable material comprises quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, and / or metallic nanoparticles. The third optically readable material may comprise a plurality of quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, and / or metallic nanoparticles.

[0047] In some embodiments, the third optically readable material comprises a colored compound.

[0048] In some embodiments, the third optically readable material comprises a fluorescent compound.A fluorescent compound is an emitter of electromagnetic radiation, or in other words, a compound that is capable of emitting electromagnetic radiation when excited (eg, by exciting electromagnetic radiation).

[0049] Fluorescent compounds may include small molecules. Fluorescent compounds suitably include polyunsaturated compounds, such as polyaromatic compounds. Suitable examples of fluorescent compounds include rhodamine dyes, cyanine dyes, phthalocyanine dyes, porphyrin dyes and quinacridones. Rhodamine dyes and cyanine dyes are preferred. Rhodamine dyes may be selected from rhodamine 6G, rhodamine 123 and / or rhodamine B. Cyanine dyes may be selected from Cy2, Cy3, Cy3.5, Cy5, C5.5, Cy7 and / or Cy7.5.

[0050] The third optically readable material may be poorly soluble in the solvent or insoluble in the solvent. At a temperature of 20° C. and a pressure of 100 kPa, the second optically readable material may have a solubility in the solvent of less than 100 mg / mL, such as less than 50 mg / mL, such as less than 10 mg / mL, for example less than 1 mg / mL. The mixture of the second optically readable material, the third optically readable material and the solvent is suitably a suspension of the third optically readable material.

[0051] The third optically readable material and the solvent may be uniformly mixed. The third optically readable material uniformly mixed in the solvent may advantageously provide a uniform background emission for the optically readable PUF coating composition.

[0052] The third optically readable material may be added to the solvent in an amount from 10 mg / mL to 500 mg / mL, such as from 50 mg / mL to 200 mg / mL, such as from 80 mg / mL to 150 mg / mL, based on the total volume of the mixture.

[0053] Preferably, in embodiments where a third optically readable material is added, the second optically readable material is soluble in the solvent, while the third optically readable material is insoluble or poorly soluble in the solvent. The physical interaction between the second optically readable material and the third optically readable material advantageously allows the third optically readable material to be uniformly dispersed in the mixture, for example by allowing the third optically readable material to dissolve in the mixture.

[0054] The mixture can be added to the coating composition so that the second optically readable material (and the third optically readable material if present) is present in an amount of from 0.1 mg / mL to 15 mg / mL (such as from 0.5 mg / mL to 10 mg / mL, such as from 1 mg / mL to 5 mg / mL) based on the total volume of the optically readable PUF coating composition. The mixture can be added to the coating composition so that the second optically readable material (and the third optically readable material if present) is present in an amount of from 0.01 wt% to 1.5 wt% (such as from 0.05 wt% to 1.0 wt%, such as from 0.08 wt% to 0.4 wt%) based on the total weight of the optically readable PUF coating composition.

[0055] The method of the first aspect suitably comprises intimately mixing the mixture and the coating composition.

[0056] In the method of the first aspect, the first optically readable material may be added to the coating composition before the mixture comprising the second optically readable material, the third optically readable material (if present) and the solvent. Alternatively, the mixture comprising the second optically readable material, the third optically readable material (if present) and the solvent may be added to the coating composition before the first optically readable material is added.

[0057] The method of the first aspect may comprise increasing the entropy of the coating composition by adding an optically readable material and optionally a solvent to at least two parts of the coating composition and then combining the parts of the coating composition.

[0058] Preparing at least two separate parts of the coating composition and then combining them together advantageously allows the uniformity of the optically readable material in each part to be adjusted independently. For example, one part of the coating composition may include a non-uniform distribution of optically readable material, while another part of the coating composition may include a uniform distribution of optically readable material. Thus, the non-uniform distribution may advantageously be unaffected by the preparation of the uniform distribution.

[0059] The optically readable material suitably comprises at least a first optically readable material as defined herein. The optically readable material may comprise two or more optically readable materials. The optically readable material may also comprise a second optically readable material and / or a third optically readable material as defined herein. For example, the optically readable material may comprise a first optically readable material and a second optically readable material; a first optically readable material and a third optically readable material; or a first optically readable material, a second optically readable material, and a third optically readable material.

[0060] Preferably, each part of the coating composition is different. Suitably, different optically readable materials or combinations of optically readable materials may be added to each part. For example, a first optically readable material may be added to a first part of the coating composition, and a second optically readable material may be added to a second part of the coating composition. A third optically readable material may be added to a third part of the coating composition, or a third optically readable material may be added to a second part of the coating composition comprising a second optically readable material.

[0061] The solvent may be added to one or more parts of the coating composition. Preferably, the solvent is mixed with the optically readable material before being added to a part of the coating composition. In some embodiments, each optically readable material is mixed with a solvent before being added to a part of the coating composition. In some embodiments, no optically readable material is mixed with a solvent. In some embodiments, some optically readable materials are mixed with a solvent before being added to a part of the coating composition, while some optically readable materials are not mixed with a solvent. For example, a first optically readable material is mixed with a solvent before being added to a part of the coating composition, and the first optically readable material can be added to a second part of the coating composition without being mixed with a solvent in advance.

[0062] Preferably, the first optically readable material is not mixed with a solvent prior to being added to the first part of the coating composition. Preferably, the second optically readable material is mixed with a solvent prior to being added to the second part of the coating composition. Preferably, the third optically readable material is not mixed with a solvent prior to being added to the second part or the third part of the coating composition.

[0063] If two or more optically readable materials are added to a portion of the coating composition, the solvent is mixed with one of the optically readable materials before being added to the coating mixture, and the other optically readable materials can be added to a portion of the coating composition without prior mixing with the solvent. For example, a second optically readable material can be mixed with a solvent before being added to a second portion of the coating composition, and a third optically readable material can be added to the second portion of the coating composition without prior mixing with a solvent.

[0064] The solvent mixed with the optically readable material before being added to a part of the coating composition can include a polar solvent and / or a non-polar solvent. Preferably, the solvent includes a polar solvent. The solvent can include an organic solvent and / or an inorganic solvent. The solvent can include a mixture of an organic solvent and an inorganic solvent (such as water). Preferably, the solvent includes an organic solvent. The organic solvent suitably includes a polar organic compound with 6 or less carbon atoms. The organic solvent can include alcohols and / or ketones. Suitable examples of organic solvents include ethanol, propanol, isopropanol and acetone. Ethanol is preferred.

[0065] The parts of the coating composition may be combined by mixing.

[0066] In some embodiments, the first optically readable material and the mixture comprising the second optically readable material, the third optically readable material (if present) and the solvent can be added to separate parts of the coating composition, and then the separate parts are combined. One advantage of doing so is that the second optically readable material and the third optically readable material (if present) can be uniformly mixed into the coating composition without affecting the non-uniform distribution of the first optically readable material in the coating composition.

[0067] The method of the first aspect may include:

[0068] (a) providing a first part and a second part of a coating composition;

[0069] (b) adding a first optically readable material to the first part of the coating composition;

[0070] (c) adding a second optically readable material to the solvent to form a mixture;

[0071] (d) adding the mixture to the second part of the coating composition;

[0072] (e) combining the first part and the second part of the coating composition.

[0073] The first part and the second part can be combined by mixing. They can be combined in any suitable ratio. The first part and the second part can be combined in a volume ratio of from 1:10 to 10:1 (such as from 1:5 to 5:1, such as from 1:5 to 1:1).

[0074] According to a second aspect of the present invention, there is provided a method of producing an optically readable PUF, comprising producing an optically readable PUF coating composition according to the method of the first aspect, and applying the optically readable PUF coating composition to a substrate.

[0075] The method of the second aspect may further comprise drying or curing the optically readable PUF coating composition.

[0076] According to a third aspect of the present invention, there is provided an optically readable PUF coating composition produced according to the method of the first aspect.

[0077] According to a fourth aspect of the present invention, there is provided an optically readable PUF produced according to the method of the second aspect.

[0078] An optically readable PUF may be used as a security element.An optically readable PUF may include alignment marks to allow an optical reader to use the marks to correct for scale, perspective, and any transformations (eg, mirroring) that may be employed as part of the reading of the PUF.

[0079] A "unique" identification, such as a serial number, can be printed near the optically readable PUF to further authenticate the PUF.

[0080] According to a fifth aspect of the present invention, there is provided an article comprising a layer, the layer providing a primary function, wherein the layer comprises an optically readable PUF, the optically readable PUF providing a secondary function enabling authentication of the article.

[0081] The article of the fifth aspect comprises a functional layer with an integrated optically readable PUF. This advantageously simplifies the manufacture of the article, as the functional layer and the optically readable PUF can be prepared in a single step, rather than requiring the optically readable PUF to be applied to the functional layer in a separate step (e.g., as a stick-on label).

[0082] The primary function may be to improve the performance of an item. For example, the primary function may be to improve the strength, durability, appearance, surface texture, taste and / or smell of an item.

[0083] The item may be any item that can benefit from the authentication functionality provided by an optically readable PUF. The item may be selected from machine or equipment parts, clothing, footwear, accessories, bags, food, artwork, electronic components, certificates, ID cards, consumables, gemstones, pharmaceuticals, tax stamps, currency, packaging and labels. For example, the item may be branded clothing and an optically readable PUF may authenticate it as authentic. For another example, the item may be a tablet and a PUF may verify that the tablet is authentic.

[0084] In one embodiment, the article is a food or medicine and the layer is edible. Suitably, the layer is digestible and non-toxic.

[0085] The optically readable PUF is suitably present in substantially the entire layer. This may allow any part of the layer to be used to authenticate an item. Suitably, at least 95% (such as at least 98%, such as at least 99%) of the surface area of ​​the layer comprises the optically readable PUF. Preferably, 100% of the surface area of ​​the layer comprises the optically readable PUF.

[0086] The layer suitably forms a major surface of the article. The layer may form at least 10%, such as at least 30%, such as at least 50% of the surface area of ​​the article. The layer may form 100% of the surface area of ​​the article. In one embodiment, the article is a food or a medicine and the layer forms 100% of the surface area of ​​the article.

[0087] A portion of a layer including at least a portion of an optically readable PUF may be designated as an optically readable area. This may help improve the reliability of readings of the optically readable PUF, as readings from different portions of the layer may not be comparable. The layer may include alignment marks to allow an optical reader to use the marks to correct for scale, perspective, and any transformations (e.g., mirroring) that may be employed as part of the reading of the PUF.

[0088] A "unique" identification, such as a serial number, can be printed near the optically readable area to further authenticate the PUF.

[0089] The layer suitably comprises a polymer. The polymer may act as an adhesive, allowing the layer to adhere to the article.

[0090] The optically readable PUF suitably comprises an optically readable material.The optically readable material may be distributed non-homogeneously in the optically readable PUF.

[0091] The optically readable material may include any suitable material that can be detected optically. The optically readable material may include quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, metal nanoparticles, colored compounds and / or fluorescent compounds. Preferably, the optically readable material includes quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, metal nanoparticles and / or fluorescent compounds. The optically readable material may emit radiation of a single wavelength, or the optically readable material may emit radiation of different wavelengths, for example, radiation of wavelengths corresponding to changes in the band gap of the optically readable material. Thus, the optically readable material may be an emitter of electromagnetic radiation, or in other words, may be a material that is configured to or is generally capable of emitting electromagnetic radiation when excited (for example, by exciting electromagnetic radiation).

[0092] In some embodiments, the optically readable material comprises quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, and / or metallic nanoparticles. The optically readable material may comprise a plurality of quantum dots, quantum wires, sheets or layers of substantially two-dimensional materials, and / or metallic nanoparticles.

[0093] In some embodiments, the optically readable material includes a colored compound.

[0094] In some embodiments, the optically readable material includes a fluorescent compound. The fluorescent compound may include a small molecule. The fluorescent compound suitably includes a polyunsaturated compound, such as a polyaromatic compound. Suitable examples of fluorescent compounds include rhodamine dyes, cyanine dyes, phthalocyanine dyes, porphyrin dyes and quinacridones. Rhodamine dyes and cyanine dyes are preferred. Rhodamine dyes may be selected from rhodamine 6G, rhodamine 123 and / or rhodamine B. Cyanine dyes may be selected from Cy2, Cy3, Cy3.5, Cy5, C5.5, Cy7 and / or Cy7.5.

[0095] Suitably, the layer has been applied in a single step.

[0096] In some embodiments, the optically readable PUF is as defined in the fourth aspect of the present invention.

[0097] According to a sixth aspect of the present invention, there is provided a method of manufacturing an article according to any one of the preceding claims, the method comprising providing a layer for the article, wherein the layer provides a primary function, and wherein the layer comprises an optically readable PUF, the optically readable PUF providing a secondary function capable of authenticating the article.

[0098] Suitable features of the article, layer and optically readable PUF are as described in the fifth aspect.

[0099] Providing the article with a layer may comprise applying a coating composition to a substrate. The coating composition may be dried or cured. The coating composition may comprise the optically readable PUF coating composition of the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0100] For a better understanding of the invention, and in order to show how embodiments of the invention may be implemented, reference will now be made, by way of example, to the accompanying drawings, in which:

[0101] FIG. 1( a ) depicts a flash photograph of a label formed from ink A, and FIG. 1( b ) depicts a flash photograph of a label formed from ink C, wherein ink C is an optically readable PUF according to the fourth aspect of the present invention;

[0102] Figure 2(a) depicts a logo created from a tag formed from ink A, and Figure 2(b) depicts a logo created from a tag formed from ink C, wherein ink C is an optically readable PUF according to the fourth aspect of the present invention;

[0103] Figure 3 schematically depicts a general method associated with the method of the first aspect of the invention;

[0104] Figure 4 Schematically depicting different methods associated with example embodiments;

[0105] Figure 5 schematically depicts a general method associated with the method of the second aspect of the invention;

[0106] Figure 6 schematically depicts an article according to a fifth aspect of the invention;

[0107] Figure 7 The general method associated with the method of the sixth aspect of the invention is schematically depicted. DETAILED DESCRIPTION

[0108] definition

[0109] Inter-Hamming distance (inter-HD): The number of bits that differ between two identifiers extracted from two different tags divided by the total number of bits in the identifier. The ideal value is 0.5.

[0110] Intra-Hamming distance (intra-HD): The number of bits that differ between two identifiers extracted from the same tag divided by the total number of bits in the identifier.

[0111] Uniformity: The ratio of 0s to 1s in the logo. The ideal value is 0.5.

[0112] Degrees of Freedom (DOF): The maximum number of bits required to fully unambiguously identify an object. A high DOF is desirable.

[0113] Decidability: A measure of the separation of the distributions of inter- and intra-Hamming distances. High decidability is desirable.

[0114] Example 1

[0115] Rhodamine 6G was dispersed in ethanol to form a 100 mg / ml solution. 25 μl of this solution was added to the UV curing lacquer and mixed for 15 minutes using a mixing head at 400 RPM to form Ink A including Rhodamine 6G at a concentration of 2.5 mg / ml.

[0116] Rhodamine B was added directly to the UV curing lacquer and mixed using a mixing head at 400 RPM for 5 minutes to form Ink B including Rhodamine B at a concentration of 2.5 mg / ml.

[0117] Ink B was mixed with ink A at a volume ratio of 1:3 for 5 minutes using a mixing head with a rotation speed of 400 RPM to form ink C.

[0118] Example 2

[0119] Rhodamine 6G was added directly to the UV curing lacquer and mixed using a mixing head at 400 RPM for 5 minutes to form Ink A including Rhodamine 6G at a concentration of 0.1 mg / ml.

[0120] Rhodamine 6G was dispersed in ethanol to form a 100 mg / ml solution. 50 mg of quinacridone was mixed with 1 ml of the solution to form a mixture comprising 2 parts of rhodamine 6G to 1 part of quinacridone by weight.

[0121] This mixture was added to Ink A and mixed using a mixing head at 500 RPM for 15 minutes to form Ink B.

[0122] Example 3

[0123] Ink A and Ink C from Example 1 were separately applied to a substrate and cured for 60 seconds using a mercury vapor UV lamp to form a label.

[0124] The emission from the tags was measured by flash photographing the tags using a smartphone camera. The photograph is shown in Figure 1. Background emission from uniformly dispersed Rhodamine 6G is visible across the entirety of the tags formed by Ink A (Figure 1(a)) and Ink C (Figure 1(b)). Spots of non-uniformly dispersed Rhodamine B are visible in the tag formed by Ink C.

[0125] The logos are created using the image of each tag as the source. These logos are shown in Figure 2. Figure 2(a) corresponds to ink A and Figure 2(b) corresponds to ink C.

[0126] The performance indexes of the two logos in Figure 2 are shown in the following table:

[0127] Ink A C Inter-slice-HD (mean, standard deviation): 0.476,0.015 0.488,0.005 On-chip - HD (mean, standard deviation) 0.406,0.028 0.383,0.025 Uniformity 0.65 0.49 Degree of freedom (bit) 1100 1468 Decidability 3.78 5.67

[0128] Inter-chip-HD values ​​were generated by comparing multiple labels generated for each type (A and C). Ink C generally exhibited superior performance indices compared to Ink A.

[0129] Detailed Description of Example Embodiments

[0130] Figure 3 A method for making an optically readable PUF coating composition is schematically depicted. First, a coating composition is provided (a). A first optically readable material is added to the coating composition (b). A second optically readable material and a solvent are mixed to form a mixture (c). The mixture is added to the coating composition (d).

[0131] Figure 4 A preferred method of making an optically readable PUF coating composition is schematically depicted. First, a coating composition (a1) is provided in a first part, and a coating composition (a2) is provided in a second part. A first optically readable material is added to the first part of the coating composition (b). A second optically readable material is added to a solvent to form a mixture (c). The mixture is added to the second part of the coating composition (d). The first and second parts of the coating composition are combined (e).

[0132] Figure 5 A method for producing an optically readable PUF is schematically depicted. First, a coating composition is provided (a). A first optically readable material is added to the coating composition (b). A second optically readable material and a solvent are mixed to form a mixture (c). The mixture is added to the coating composition (d). After steps (b) and (d), which may be performed in any order, the coating composition is applied to a substrate (f). The coating composition may be dried or cured after being applied to the substrate (g).

[0133] Figure 6 An article 10 according to a fifth aspect of the invention is schematically depicted. The article 10 comprises a layer 20, the layer 20 providing a primary function, wherein the layer 20 comprises an optically readable PUF, the optically readable PUF providing a secondary function of being able to authenticate the article. A portion of the layer 20 comprising at least a portion of the optically readable PUF may be designated as an optically readable area 30.

[0134] Figure 7A method of manufacturing an article is schematically depicted. The article is provided with a layer (h), wherein the layer provides a primary functionality, and wherein the layer comprises an optically readable PUF providing a secondary functionality enabling authentication of the article.

[0135] While certain preferred embodiments have been shown and described, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the appended claims.

[0136] Attention should be paid to all documents and materials related to the present application filed concurrently with or prior to the present specification, as well as documents and materials disclosed for public inspection with the present specification, the contents of all these documents and materials are incorporated herein by reference.

[0137] All features disclosed in this specification (including any accompanying claims, abstract and drawings) and / or all steps of any method or process so disclosed may be combined in any combination, unless at least some of the features and / or steps are mutually exclusive combinations.

[0138] Unless expressly stated otherwise, each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose. Therefore, unless expressly stated otherwise, each feature disclosed is only one example in a general series of equivalent or similar features.

[0139] The invention is not limited to the details of the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification (including any attached claims, abstract and drawings), or any novel step or any novel combination of steps in any disclosed method or process.

Claims

1. A method of making an optically readable PUF coating composition, the method comprising increasing the entropy of the coating composition by adding a first optically readable material to the coating composition.

2. The method according to claim 1, wherein: The coating composition is a paint.

3. A method according to any preceding claim, comprising dispersing the first optically readable material non-homogeneously in the coating composition.

4. A method according to any one of the preceding claims, wherein: The first optically readable material comprises a fluorescent compound.

5. The method according to claim 4, wherein: The fluorescent compound includes rhodamine dye, cyanine dye, phthalocyanine dye, porphyrin dye and / or quinacridone.

6. The method of any one of the preceding claims, further comprising mixing a second optically readable material and a solvent to form a mixture, and adding the mixture to the coating composition.

7. The method of claim 6, comprising uniformly mixing the second optically readable material and the solvent.

8. The method according to claim 6 or 7, wherein: The solvent includes alcohol and / or ketone.

9. A method according to any one of the preceding claims, comprising: The entropy of the coating composition is increased by adding an optically readable material and optionally a solvent to at least two parts of the coating composition and then combining the parts of the coating composition.

10. The method according to any one of the preceding claims, comprising the steps of: (a) providing a first part and a second part of a coating composition; (b) adding a first optically readable material to the first part of the coating composition; (c) adding a second optically readable material to the solvent to form a mixture; (d) adding the mixture to the second part of the coating composition; (e) combining the first part and the second part of the coating composition.

11. A method for producing an optically readable PUF, comprising: An optically readable PUF coating composition is produced according to the method of any one of the preceding claims and applied to a surface.

12. The method of claim 11, further comprising drying or curing the optically readable PUF coating composition.

13. An optically readable PUF coating composition produced according to the method of any one of claims 1 to 10.

14. An optically readable PUF produced according to the method of claim 11 or 12.

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