WO2014084853A1

WO2014084853A1 - Magnetothermal fibers

Info

Publication number: WO2014084853A1
Application number: PCT/US2012/067346
Authority: WO
Inventors: Vincenzo Casasanta Iii; Aya Seike
Original assignee: Empire Technology Development Llc
Priority date: 2012-11-30
Filing date: 2012-11-30
Publication date: 2014-06-05

Abstract

Magnetothermal fibers are described. The fibers include magnetic particles that are configured to produce heat in a time-varying magnetic field. A detectable tag for an article of manufacture is described. The tag includes fibers having magnetic particles configured to produce heat when exposed to a time-varying magnetic field. Methods for making magnetothermal fibers and detectable tags having magnetothermal fibers are described.

Description

MAGNETOTHERMAL FIBERS

BACKGROUND

[0001] Counterfeiting is widespread in retail goods such as clothes, shoes, and accessories. Magnetic security tags are used by many retailers to ensure the security of some original, expensive products. However, one of the methods used by manufacturers of counterfeit products is to use identifier tags for the counterfeit products that are identical to the original product. Thus, if such a counterfeit product reaches the retailers, it is likely that the retailers may not realize the counterfeit nature of the product. In such cases, even magnetic security tags are not useful. Unique and difficult to duplicate identifier tags are therefore desired.

SUMMARY

[0002] This disclosure is not limited to the particular systems, devices and methods described, as these may vary. The terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope.

[0003] As used in this document, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art. Nothing in this disclosure is to be construed as an admission that the embodiments described in this disclosure are not entitled to antedate such disclosure by virtue of prior invention. As used in this document, the term "comprising" means "including, but not limited to." [0004] In some embodiments, a fiber having magnetic particles is described. The magnetic particles are configured to produce heat when exposed to time-varying magnetic field.

[0005] In some embodiments, a detectable tag for an article of manufacture is described. The tag may be made from fibers having magnetic particles that are configured to produce heat when exposed to a time-varying magnetic field.

[0006] In some embodiments, a method of making fibers having magnetic particles is described. The method may include contacting a plurality of fibers with a binder or an adhesive, and contacting magnetic particles with the binder or the adhesive.

[0007] In some embodiments, a method for making fibers having magnetic particles may include melting a starting material to form a melt, contacting the magnetic particles with the melt and drawing fibers from the melt. The starting material may include polyamides, polyimides, polyolefin, polyester, acrylic, polyvinyl chloride, polyvinyl alcohol, polyurethane, polyurethane-polyurea, acrylonitrile, polybenzimidazole, poly(p-phenylene- 2,6-benzobisoxazole), or a combination thereof.

[0008] In some embodiments, a method of identifying an article of manufacture including fibers having magnetic particles is described. The method may include exposing the article of manufacture to a time-varying magnetic field, imaging the article of manufacture using an infrared camera, and identifying the article of manufacture based on an infrared pattern sensed by the infrared camera.

[0009] In some embodiments, a system for identifying an article of manufacture having a pattern comprising fibers having magnetic particles configured to produce heat in a time-varying magnetic field is described. The system may include a magnet configured to produce a time-varying magnetic field having a magnetic field magnitude of at least 1000 gauss, and an infrared camera configured to sense temperature differences within the pattern. BRIEF DESCRIPTION OF DRAWINGS

[0010] In the present disclosure, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be used, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

[0011] Figure 1 depicts an illustrative schematic of a detectable tag made from fibers having magnetic particles.

[0012] Figure 2A depicts an illustrative schematic of a detectable tag made from fibers having magnetic particles in presence of a time-varying magnetic field.

[0013] Figure 2B depicts an illustrative schematic of a detectable tag made from fibers having magnetic particles in presence of a time-varying magnetic field as seen by an infrared camera.

DETAILED DESCRIPTION

[0014] Described herein are structures and methods of making the structures, that may be used in making identifier tags for articles of manufacture. Also described are methods of identifying articles of manufacture using such identifier tags. As such, some structures may include one or more fibers having magnetic particles that are configured to produce heat when exposed to a time-varying magnetic field. Typical structures may include fibers having magnetic particles woven into particular patterns. In general, such patterns may be indistinguishable under normal conditions and normal lighting. However, when articles of manufacture having such patterns are exposed to a time-varying magnetic field, the heat produced by the magnetic particles may render the patterns visible by emission of infrared light or heat.

[0015] As used herein, the term "particle" refers to a particle that has an average size of greater than or equal to about 1 nanometer (nm) and less than or equal to about 10 micrometer (μιη). Examples of sizes of particles include, but are not limited to, 1 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 125 nm, 150 nm, 175 nm, 200 nm, 225 nm, 250 nm, 275 nm, 300 nm, 325 nm, 350 nm, 375 nm, 400 nm, 425 nm, 450 nm, 475 nm, 500 nm, 525 nm, 550 nm, 575 nm, 600 nm, 625 nm, 650 nm, 675 nm, 700 nm, 725 nm, 750 nm, 775 nm, 800 nm, 825 nm, 850 nm, 875 nm, 900 nm, 925 nm, 950 nm, 975 nm, 1 μιη, 2 μιη, 3 μιη, 4 μιη, 5 μιη, 6 μιη, 7 μιη, 8 μιη, 9 μιη, 10 μιη, or any value in a range between any two of these values.

[0016] As used herein, the term "magnetic particles" refers to particles of materials having magnetic properties. Such materials may be ferromagnetic, ferrimagnetic, or superparamagnetic. Ferromagnetic materials are materials having unpaired electrons and intrinsic electron magnetic moment having a tendency to be parallel to each other to maintain a lower energy state. Thus, ferromagnetic materials tend to have an intrinsic magnetic moment that is maintained even when an applied magnetic field is removed. Examples of ferromagnetic materials include, but are not limited to, iron, cobalt, nickel, gadolinium, dysprosium, alloys thereof, europium oxide, ferric oxide, and the like. Ferrimagnetic materials are materials having neighboring pairs of electron spins pointing in opposite directions, but having an intrinsic magnetization. The intrinsic magnetization of ferrimagnetic materials stems from optimal geometrical arrangement allowed by their crystal structure. Examples of ferrimagnetic materials include, but are not limited to, ferrites, yttrium aluminum garnet, and the like. A superparamagnet or a superparamagnetic material refers to a ferromagnet or a ferrimagnet that is sufficiently small so as to act like a single magnetic spin that is subject to Brownian motion. As a result, superparamagnets respond to magnetic fields similar to paramagnets with a significantly larger magnitude.

[0017] Magnetic particles of various embodiments may exhibit a magnetothermal effect. As used herein, the term "magnetothermal effect" refers to a production of heat in the presence of a time-varying magnetic field. As used herein, the term "time-varying magnetic field" refers to a magnetic field having a magnitude that varies with time and/or having a direction that changes with time. In various embodiments, the magnetic field may have a wave-form such as, for example, a sine wave, a biased sine wave, a sawtooth wave, a step signal, a triangular wave, a rectangular wave, an arbitrary waveform signal, and the like, or any combination thereof, and may have any frequency. In various embodiments, amplitude, phase and/or frequency of the time-varying magnetic field may be determined depending on the particular use. Mechanisms underlying the magnetothermal effect typically include hysteresis loss, Neel relaxation, or Brownian relaxation depending on the particular type of magnetic particles used in particular embodiments. Larger magnetic particles (typically, having average size greater than about 30 nm), may contain multiple magnetic domains each having a separate magnetization direction. When a time-varying magnetic field is applied, domains with magnetization directions aligning with the applied field elongate and domains with magnetization directions not aligned with the applied field contract. Because this leads to displacement of domain boundaries, increasing and decreasing magnetization curves do not coincide. This leads to loss of energy as heat and is commonly referred to as hysteresis loss. For magnetic particles that are small enough to have a single magnetic domain (superparamagnetic particles), a time-varying magnetic field causes magnetic moments to rotate and overcome an anisotropy energy barrier so that the magnetic orientation may be aligned with the applied field. When such particles relax back to equilibrium via Neel relaxation, the energy is lost as heat. In various embodiments, magnetic particles may be disposed on a fiber, thereby restricting their Brownian motion. As such, in certain embodiments, the magnetothermal effect, in various embodiments, may be generally dominated by hysteresis loss and Neel relaxation. Heat generated by magnetic particles via

Neel relaxation can be determined by using Rosensweig's model as:

P = πμ₀χ₀Η² J - (Eq. 1)

where P is the power generated with magnetic particles having a volume V, anisotropy K_u, magnetic susceptibility χ₀, and magnetic moment μ₀ are exposed to a time-varying magnetic field of intensity H and frequency f. k is the Boltzmann constant, τ₀= 10⁹ seconds, and T is the temperature.

[0018] In some embodiments, fibers having magnetic particles are described. The magnetic particles are configured to produce heat in a time-varying magnetic field. As used herein, the term "fiber" refers to any natural or synthetic fiber known in the art. In some embodiments, the fibers may include animal derived fibers such as, for example, those containing keratin, collagen, fibroin, spider silk, and the like, or a combination thereof. In some embodiments, the fibers may include plant derived fibers such as, for example, those containing lignin, cellulose, and the like, or a combination thereof. In certain embodiments, the fibers may be synthetic fibers made from materials including, but not limited to, glass, carbon, carbon nanotubes, polyamides, polyimides, polyolefin, polyester, acrylic, polyvinyl chloride, polyvinyl alcohol, polyurethane, polyurethane-polyurea, acrylonitrile, polybenzimidazole, poly(p-phenylene-2,6-benzobisoxazole), and the like, or a combination thereof. In various embodiments, the fibers may further include, for example, a binder or an adhesive coating. [0019] In various embodiments, particles of any magnetic material may be used. In some embodiments, the magnetic particles may include ferromagnetic or ferrimagnetic materials such as, for example, iron, nickel, cobalt, samarium, neodymium, gadolinium, alnico, samarium-cobalt, neodymium-iron-boron, yttrium-cobalt, manganese-zinc ferrite, nickel-zinc ferrite, strontium ferrite, barium ferrite, cobalt ferrite, iron (III) oxide, iron (II, III) oxide, yttrium iron garnet, or any a combination thereof. The magnetic particles may be, in various embodiments, of any average size known in the art such as, for example, about 1 nm, about 5 nm, about 10 nm, about 20 nm, about 30 nm, about 50 nm, about 100 nm, about 150 nm, about 200 nm, about 300 nm, about 500 nm, about 750 nm, about 1000 nm, about 2 μιη, about 3 μιη, about 4 μιη, about 5 μιη, about 6 μιη, about 7 μιη, about 8 μιη, about 9 μιη, about 10 μιη, or any value in a range between any two of these values.

[0020] In Eq. 1 above, magnetic susceptibility, χ₀, and magnetic moment, μ₀, are material properties that determine the heat produced by the particles when exposed to a magnetic field of a given magnitude. Anisotropy, K_u, and particle volume, V, depend on the particle size and shape. As such, the magnitude of the magnetic field required to produce a desired temperature change may be determined by a skilled artisan by appropriately choosing the size, shape and material of the particles. Likewise, if the magnitude of the magnetic field available is known, the size, shape and material of the particles may be suitably selected to produce a desired temperature change. In fibers of various embodiments, magnetic particles may produce a desired temperature change when exposed to a time-varying magnetic field. In some embodiments, the magnetic field may vary by at least about 1000 gauss.

[0021] The fibers having magnetic particles may be used for any suitable purpose. Various embodiments describe a detectable tag for an article of manufacture. The detectable tag may have fibers having magnetic particles configured to produce heat when exposed to a time-varying magnetic field. In some embodiments, the detectable tag may also include fibers not having magnetic particles (unmodified fibers). As such unmodified fibers may not produce any heat when exposed to a time-varying magnetic field.

[0022] Figure 1 depicts an illustrative schematic of a detectable tag made from fibers having magnetic particles. In certain embodiments, fibers having magnetic particles 102 are arranged in a pattern 100. The pattern 100 may include unmodified fibers 101. In various embodiments, the fibers having magnetic particles 102 and unmodified fibers 101 may be interwoven to form a pattern such as, for example, a barcode, a QR code, a fractal, a logo, one or more alphabets, one or more numerals, a geometric shape, and the like, or a combination thereof that conveys particular information. In some embodiments, the fibers having magnetic particles 102 may include magnetic particles of different sizes or materials so as to produce different temperature changes when exposed to a time-varying magnetic field. In such embodiments, the different fibers having magnetic particles 102 may be arranged to produce, for example, a temperature gradient or a contour map that may convey particular information.

[0023] The information conveyed by the pattern 100 may include, but is not limited to, a manufacturer, a date of manufacture, a serial number, a country of origin, materials of manufacture, directions for care, and the like, or a combination thereof. As such, this information may be used for any purpose. In some embodiments, the information is used for authenticating the article of manufacture associated with the detectable tag. In various embodiments, the article of manufacture associated with the detectable tag may be, for example, a garment, a shoe, an item of luggage, a piece of jewelry, a piece of art, a carpet, a printed circuit board, an automobile part, and the like, or a combination thereof.

[0024] In some embodiments, a detectable tag may include unmodified fibers 101 with one or more fiber materials and/or fibers having magnetic particles 102 having one or more fiber materials, one or more magnetic materials, or one or more particle sizes. For example, a detectable tag may include a pattern made using silk fibers having magnetic particles. Some fibers may have iron particles and some fibers may have cobalt particles. The pattern may additionally include unmodified silk fibers. When such a pattern is exposed to a time-varying magnetic field, the pattern may have three different temperatures which may be imaged using, for example, an infrared camera.

[0025] In various embodiments, the fibers having magnetic particles and/or the unmodified fibers may be naturally derived fibers such as, for example, animal or plant derived fibers. In some embodiments, the fibers may contain proteins and/or polypeptides such as, for example, keratin, collagen, fibroin, spider silk, and the like, or combinations thereof. Illustrative examples of sources for animal derived fibers include, but are not limited to, alpaca, angora, byssus, camel hair, cashmere, catgut, chiengora, guanaco, llama, mohair, pashmina, quiviut, rabbit, silk, sinew, spider silk, wool, yak, and the like. In some embodiments, the fibers may contain, for example, lignin, cellulose, or combinations thereof. Illustrative examples of sources for plant derived fibers include, but are not limited to, abaca, bagasse, bamboo, coir, cotton, flax, hemp, jute, kapok, kenaf, pina, raffia, ramie, sisal, tree- bark, wood, or combinations thereof. In some embodiments, the fibers may be synthetically formed fibers including naturally occurring materials such as, for example, art silk, lyocell rayon, modal rayon, rayon, triacetate, or combinations thereof.

[0026] In certain embodiments, the fibers having magnetic particles and/or the unmodified fibers may be synthetic fibers containing, for example, glass, carbon, carbon nanotubes, polyamides, polyimides, polyolefin, polyester, acrylic, polyvinyl chloride, polyvinyl alcohol, polyurethane, polyurethane-polyurea, acrylonitrile, polybenzimidazole, poly(p-phenylene-2,6-benzobisoxazole), and the like, or combinations thereof. In some embodiments, the unmodified fibers and/or the fibers having magnetic particles may be blends of natural and synthetic fibers. The fibers having magnetic particles may, in some embodiments, further include a binder and/or an adhesive for binding the magnetic particles to the fibers, for binding the fibers to a matrix, or for binding the fibers to each other.

[0027] The detectable tags of various embodiments may be used for any suitable purpose known in the art. In some embodiments, the detectable tags may be used for identifying and authenticating articles of manufacture. For example, the detectable tags may be associated with articles including, but not limited to, dresses, blouses, tunics, skirts, shorts, shawls, scarfs, suits, vests, shirts, pants, ties, jackets, sweaters, cardigans, footwear, purses, handbags, wallets, linens, rugs, carpets, beddings, curtains, comforters, blankets, and/or the like. In some embodiments, the detectable tags may be associated with articles used in sports and recreation such as, for example, parachutes, sails, gliders, kites, diving suits, ropes, and/or the like. In various embodiments, the detectable tags may be incorporated within the particular articles they are associated with and may not be visible under normal light conditions. In certain embodiments, for example, a detectable tag may be in the form of a logo of the manufacturer. When such a tag is exposed to a suitable time-varying magnetic field, the magnetic particles produce heat allowing the logo to be visualized using, for example, an infrared camera. As such, detectable tags of various embodiments may be used for distinguishing genuine articles having such tags from a particular manufacturer from counterfeit articles or knock-offs not having such tags.

[0028] Embodiments are further directed to systems and methods for identifying an article of manufacture including fibers having magnetic particles. In some embodiments, the fibers having magnetic particles may form a detectable tag that is associated with the article of manufacture. In certain embodiments, the detectable tag includes a pattern made from fibers having magnetic particles and unmodified particles in the form of, for example, a barcode, a QR code, a fractal, a logo, one or more alphabets, one or more numerals, a geometric shape, and the like, or a combination thereof that conveys particular information. As described herein, in certain embodiments, the pattern may include fibers containing one or more fiber materials, one or more magnetic materials, and/or one or more particle shapes and/or sizes, or the unmodified fibers of one or more fiber materials.

[0029] In some embodiments, a method of identifying an article of manufacture may include exposing the article of manufacture to a time-varying magnetic field, imaging the article of manufacture using an infrared camera, and identifying the article of manufacture based on an infrared pattern sensed by the infrared camera. Figures 2A and 2B depict an illustrative schematic of a detectable tag made from fibers having magnetic particles in the presence of a time-varying magnetic field as seen by an infrared camera. As shown in Figure 2B the detectable tag 201 shows a pattern 202 when imaged by an infrared camera as defined by the fibers having magnetic particles when the detectable tag 201 is exposed to a time- varying magnetic field.

[0030] In various embodiments, the time-varying magnetic field may be generated by, for example, an electromagnet, a solenoid, an induction coil, an oscillating permanent magnet, and the like, or any combination thereof. As described herein the time-varying magnetic field, depending on the magnitude of the magnetic field and the frequency, may heat the magnetic particles of the detectable tag 201, thereby increasing the temperature of the fibers having the magnetic particles. As such, when imaged by an infrared camera, in a time-varying magnetic field the fibers having magnetic particles can be distinguished from unmodified fibers. In general, the intensity of an image obtained from an infrared camera depends on the temperature. As such, a detectable tag having magnetic particles of different magnetic materials, different combinations of those magnetic materials, different arrangement or different particle sizes and/or shapes may be distinguished by their respective intensities when imaged by an infrared camera even when exposed to the same time -varying magnetic field. In some embodiments, the detectable tag 201 may include patterns having unmodified fibers and/or fibers having magnetic particles with one or more magnetic materials, one or more particle sizes, or one or more particle shapes. In certain embodiments, the unmodified fiber and/or the fibers having magnetic particles in a detectable tag 201 may be of one or more materials.

[0031] Further embodiments are directed to systems for identifying articles of manufacture. In some embodiments, a system for identifying an article of manufacture having a pattern may include a magnet configured to produce a time-varying magnetic field having a magnetic field of magnitude of at least about 1000 gauss, and an infrared camera. The pattern may include fibers having magnetic particles configured to produce heat when exposed to a time-varying magnetic field. The infrared camera may be used for sensing the temperature differences within the pattern produced on exposure to the magnetic field. In various embodiments, the system may include a display device attached to the infrared camera for displaying the pattern sensed by the infrared camera. In certain embodiments, the pattern may include unmodified fibers and/or fibers having magnetic particles having one or more magnetic materials, one or more particle shapes, and/or one or more particle sizes. In some embodiments, the unmodified fibers and/or the fibers having magnetic particles may be of one or more fiber materials described herein.

[0032] The fibers having magnetic particles of various embodiments may be made by any method. In some embodiments, a method of making fibers having magnetic particles may include contacting one or more fibers with a binder and/or an adhesive, and contacting magnetic particles with the one or more fibers having the binder and/or the adhesive. The one or more fibers may be of any material known in the art including natural fibers, synthetic fibers, or blends thereof. The magnetic particles may be of any magnetic material known in the art such as, for example, ferromagnetic materials or ferrimagnetic materials. The particles of various embodiments may have an average size of, for example, about 1 nm, about 5 nm, about 10 nm, about 20 nm, about 30 nm, about 50 nm, about 100 nm, about 150 nm, about 200 nm, about 300 nm, about 500 nm, about 750 nm, about 1000 nm, about 2 μιη, about 3 μιη, about 4 μιη, about 5 μιη, about 6 μιη, about 7 μιη, about 8 μιη, about 9 μιη, about 10 μιη, or any value in a range between any two of these values.

[0033] The binder and/or the adhesive may be contacted with the one or more fibers by any method known in the art. For example, in some embodiments, contacting the one or more fibers with a binder and/or an adhesive may include pulling the one or more fibers through a binder and/or an adhesive solution or mixture. In certain embodiments, the binder and/or the adhesive may be aerosolized and sprayed on the one or more fibers. In some embodiments, for example, a roll or a bobbin having the one or more fibers may be immersed in a mixture or solution of the binder and/or the adhesive for a suitable period of time. The excess binder and/or adhesive may be removed, and the roll or bobbin may be dried and/or annealed. Likewise, the magnetic particles may be contacted with the one or more fibers having the binder and/or the adhesive by any method known in the art. In some embodiments, the magnetic particles may be suspended in a non-reacting liquid, aerosolized, and sprayed on the one or more fibers having the binder and/or the adhesive. In certain embodiments, the magnetic particles may be sprayed on the one or more fibers having the binder and/or the adhesive as a powder. In particular embodiments, the one or more fibers having the binder and/or adhesive may be immersed in a powder or a suspension, and the one or more fibers dried and/or annealed.

[0034] In some embodiments a method of making fibers having magnetic particles may include melting a starting material to form a melt, contacting the magnetic particles with the melt, and drawing fibers from the melt. The starting material may include polyamides, polyimides, polyolefin, polyester, acrylic, polyvinyl chloride, polyvinyl alcohol, polyurethane, polyurethane-polyurea, acrylonitrile, polybenzimidazole, poly(p-phenylene- 2,6-benzobisoxazole), and the like, or a combination thereof.

[0035] In various embodiments, melting the starting material may include heating the starting material to a temperature of about 100 °C to about 450 °C depending on the particular starting material.

[0036] The magnetic particles may be of any magnetic material known in the art and of any size known in the art, or as described herein. In some embodiments, contacting the magnetic particles with the melt may include adding the magnetic particles to the melt, stirring the magnetic particles in to the melt, and/or flowing the melt through a layer of magnetic particles. In various embodiments, it may be desirable to have the magnetic particles homogenously dispersed within the melt. As such, contacting the magnetic particles with the melt may, in some embodiments, further include steps such as, for example, maintaining the temperature of the melt, heating the melt to further increase the temperature, agitating the melt, and the like, or a combination thereof.

EXAMPLES

Example 1 : Nylon fibers with magnetite particles

[0037] Nylon 6,6 is heated to a temperature of about 260 °C to form a nylon 6,6 melt. Magnetite (Fe₃0₄) particles having an average size of about 30 nm are added to the melt and mixed so as to homogenously distribute the particles in the melt. Fibers are extruded from the particle mixed melt and rolled on to spindles for future use.

Example 2: Detectable tag using nylon fibers

[0038] Nylon 6,6 fibers and magnetic nylon 6,6 fibers of Example 1 are woven together to form a barcode where the dark portion of the barcode is made of magnetic nylon 6,6 fibers of Example 1 and the light portion of the barcode is made of nylon 6,6. The barcode is arranged such that the color-inverse of the barcode encodes a Universal Product Code (UPC) for a particular product. The barcode is not visually detectable by eye under normal lighting conditions.

Example 3 : Identifying an article of clothing having a magnetic detectable tag

[0039] The detectable tag of Example 2 is attached to an article of clothing (e.g. a jacket, a shirt, a dress, a suit, pants, etc.). When the article of clothing is exposed to a time- varying magnetic field having a magnitude of about 1.5 kilogauss (kG), the magnetic nylon 6,6 fibers produce heat such that the dark portion of the barcode is hotter than the light portion of the barcode. When viewed through an infrared camera, the hotter (dark portion) areas of the barcode glow and appear bright, whereas the light portions of the barcode appear dark. This barcode is read by a barcode scanner to decode a UPC encoded by the infrared image. Without the magnetic field, the magnetic nylon 6,6 and nylon 6,6 in the detectable tag are identical and indistinguishable under normal light as well as infrared light.

Example 4: Authenticating an handbag having a magnetic tag

[0040] A detectable tag in the form of a brand logo made from polyester fibers having nickel particles (average size about 50 nm) and unmodified polyester fibers is incorporated in the inner lining of a handbag. The logo is not visually detectable under normal lighting conditions. A shipment of handbags is intercepted at a country's border as part of an anti-counterfeiting campaign. Each bag in the shipment is exposed to an AC magnetic field having a magnitude of about 1.5 kG and visualized through an infrared camera. Genuine bags having a logo visible through the infrared camera are allowed to be imported (authenticated) while bags without the logo are destroyed. Example 5: Authenticating a carpet having a magnetic tag

[0041] A detectable tag similar to the one in Example 4 is incorporated into a carpet. The tag is not visible under normal light conditions, but a genuine carpet can be distinguished from a counterfeit by exposing the carpet to an AC magnetic field having a magnitude of about 1.5 kG and visualizing through an infrared camera. A carpet with a tag visible through the infrared camera is genuine whereas a carpet without a tag is counterfeit.

[0042] The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent methods and apparatuses within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds, compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0043] With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

[0044] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., " a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., " a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

[0045] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0046] As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and a combination of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as "up to," "at least," and the like include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1-3 cells refers to groups having 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers to groups having 1, 2, 3, 4, or 5 cells, and so forth.

[0047] Various of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art, each of which is also intended to be encompassed by the disclosed embodiments.

Claims

CLAIMS What is claimed is:

1. A fiber comprising magnetic particles configured to produce heat when exposed to a time-varying magnetic field.

2. The fiber of claim 1, wherein the magnetic particles have a diameter of about 1 nm to about 10 μιη.

3. The fiber of claim 1 , wherein the magnetic particles comprise ferromagnetic materials, ferrimagnetic materials, or superparamagnetic materials.

4. The fiber of claim 1, wherein the magnetic particles comprise iron, nickel, cobalt, samarium, neodymium, gadolinium, alnico, samarium-cobalt, neodymium-iron-boron, yttrium-cobalt, manganese-zinc ferrite, nickel-zinc ferrite, strontium ferrite, barium ferrite, cobalt ferrite, iron (III) oxide, iron (II, III) oxide, yttrium iron garnet, or any a combination thereof.

5. The fiber of claim 1, further comprising naturally occurring fibers, animal derived fibers, plant derived fibers, or a combination thereof.

6. The fiber of claim 1, further comprising polypeptides, keratin, collagen, fibroin, spider silk, or a combination thereof.

7. The fiber of claim 1, further comprising cellulose, lignin, or a combination thereof.

8. The fiber of claim 1, further comprising polyamides, polyimides, polyolefin, polyester, acrylic, polyvinyl chloride, polyvinyl alcohol, polyurethane, polyurethane- polyurea, acrylonitrile, polybenzimidazole, poly(p-phenylene-2,6-benzobisoxazole), or a combination thereof.

9. The fiber of claim 1, further comprising glass, carbon, or carbon nanotubes.

10. The fiber of claim 1, further comprising a binder or an adhesive coating.

1 1. The fiber of claim 1 , wherein the magnetic field has a magnitude of at least about 1000 gauss.

12. A detectable tag for an article of manufacture, the tag comprising fibers having magnetic particles configured to produce heat when exposed to a time-varying magnetic field.

13. The detectable tag of claim 12, wherein the fibers having magnetic particles are arranged in a pattern.

14. The detectable tag of claim 13, wherein the pattern identifies one or more of a manufacturer, a manufacture date, a serial number, materials of manufacture, and a country of origin.

15. The detectable tag of claim 13, wherein the pattern is identified by an infrared camera.

16. The detectable tag of claim 12, wherein the fibers comprise naturally occurring fibers, animal derived fibers, plant derived fibers, or a combination thereof.

17. The detectable tag of claim 12, wherein the fibers comprise polypeptides, keratin, collagen, fibroin, spider silk, or a combination thereof.

18. The detectable tag of claim 12, wherein the fibers comprise cellulose, lignin, or a combination thereof.

19. The detectable tag of claim 12, wherein the fibers comprise polyamides, polyimides, polyolefin, polyester, acrylic, polyvinyl chloride, polyvinyl alcohol, polyurethane, polyurethane-polyurea, acrylonitrile, polybenzimidazole, poly(p-phenylene- 2,6-benzobisoxazole), or a combination thereof.

20. The detectable tag of claim 12, wherein the fibers comprise glass, carbon, carbon nanotubes, or a combination thereof.

21. The detectable tag of claim 12, wherein the fibers comprise at least one binder or at least one adhesive coating.

22. The detectable tag of claim 12, wherein the magnetic particles comprise ferromagnetic materials, ferrimagnetic materials, or superparamagnetic materials.

23. The detectable tag of claim 12, wherein the magnetic field has a magnitude of at least about 1000 gauss.

24. A method of making fibers having magnetic particles, the method comprising: contacting a plurality of fibers with a binder, an adhesive, or both; and contacting magnetic particles with the binder, the adhesive, or both.

25. The method of claim 24, wherein contacting magnetic particles comprises spraying an aerosol comprising magnetic particles on the plurality of fibers.

26. The method of claim 24, wherein the magnetic particles comprise ferromagnetic materials, ferrimagnetic materials, or superparamagnetic materials.

27. The method of claim 24, wherein the magnetic particles are configured to produce heat when exposed to a time-varying magnetic field.

28. A method for making fibers having magnetic particles, the method comprising: melting a starting material to form a melt;

contacting the magnetic particles with the melt; and

drawing fibers from the melt,

wherein the starting material comprises polyamides, polyimides, polyolefin, polyester, acrylic, polyvinyl chloride, polyvinyl alcohol, polyurethane, polyurethane- polyurea, acrylonitrile, polybenzimidazole, poly(p-phenylene-2,6-benzobisoxazole), or a combination thereof.

29. The method of claim 28, wherein contacting the magnetic particles with the melt comprises mixing the magnetic particles in the melt.

30. The method of claim 28, wherein the magnetic particles comprise ferromagnetic materials, ferrimagnetic materials, or superparamagnetic materials.

31. The method of claim 28, wherein the magnetic particles are configured to produce heat when exposed to a time-varying magnetic field.

32. A method of identifying an article of manufacture comprising fibers having magnetic particles, the method comprising: exposing the article of manufacture to a time-varying magnetic field;

imaging the article of manufacture using an infrared camera; and identifying the article of manufacture based on an infrared pattern sensed by the infrared camera.

33. The method of claim 32, wherein the magnetic particles are configured to produce heat when exposed to a time-varying magnetic field.

34. The method of claim 32, wherein the magnetic field has a magnitude of at least about 1000 gauss.

35. The method of claim 32, wherein the magnetic particles comprise ferromagnetic materials, ferrimagnetic materials, or superparamagnetic materials.

36. The method of claim 32, wherein identifying the article of manufacture is based on identifying one or more of a manufacturer, a manufacture date, a serial number, a production date, and a country of origin.

37. The method of claim 32 wherein the fibers comprise naturally occurring fibers, animal derived fibers, plant derived fibers, or a combination thereof.

38. The method of claim 32, wherein the fibers comprise polypeptides, keratin, collagen, fibroin, spider silk, or a combination thereof.

39. The method of claim 32, wherein the fibers comprise cellulose, lignin, or combination thereof.

40. The method of claim 32, wherein the fibers comprise polyamides, polyimides, polyolefin, polyester, acrylic, polyvinyl chloride, polyvinyl alcohol, polyurethane, polyurethane-polyurea, acrylonitrile, polybenzimidazole, poly(p-phenylene-2,6- benzobisoxazole), or a combination thereof.

41. The method of claim 32, wherein the fibers comprise glass, carbon, or carbon nanotubes.

42. A system for identifying an article of manufacture having a pattern comprising fibers having magnetic particles configured to produce heat in a time-varying magnetic field, the system comprising: a magnet configured to produce a time-varying magnetic field having a magnetic field magnitude of at least about 1000 gauss; and

an infrared camera configured to sense temperature differences within the pattern to identify information associated with the article of manufacture.