Multilayered structures and uses thereof in security markings

Patent metadata

Field	Value
Publication number	US-11194094-B2
Application number	US-201916441982-A
Country	US
Kind code	B2
Filing date	Jun 14, 2019
Priority date	Nov 5, 2018
Publication date	Dec 7, 2021
Grant date	Dec 7, 2021

Abstract

A security marking has a physically unclonable function (PUF) wherein the PUF includes a disordered multilayer photonic crystal structure having an electromagnetic transmission and/or reflection spectrum and/or spectra upon receipt of electromagnetic radiation within a photonic bandgap region of the structure that is unique to the structure.

First claim

Having described the invention, the following is claimed:

1. A method of providing a physical object with a security marking, the method comprising:
multilayer coextruding one or more polymer materials to form disordered and/or non-uniform polymer layers and multiplying the disordered and/or non-uniform polymer layers to form a film that has a randomness defined by disorder and/or non-uniformity within the film that results from the multilayer coextrusion and multiplying processes;
adding the film to an object to be marked, the film having an electromagnetic transmission and/or reflection spectrum and/or spectra upon receipt of electromagnetic radiation within a photonic bandgap region of the film that is unique to the film;
applying electromagnetic radiation to the film;
detecting electromagnetic radiation spectrum and/or spectra of the electromagnetic radiation transmitted through and/or reflected from the film; and
converting the electromagnetic transmission and/or reflection spectrum and/or spectra to a signal that is indicative of the film.

2. The method of claim 1 , wherein the converting step comprises determining from the electromagnetic transmission and/or reflection spectrum and/or spectra at least one of:
the position of one or more characteristic features within the spectrum and/or spectra;
one or more statistical measures characterizing the spectrum and/or spectra; or
one or more quantized spectral values of the spectrum and/or spectra.

3. The method of claim 2 , wherein the converting step comprises a binary question of whether or not the spectrum shows a peak within a spectral region over a defined wavelength.

4. The method of claim 1 , further comprising validating the signal by comparing a characteristic of the signal with a characteristic of a signal obtained from a previous measurement.

5. The method of claim 1 , wherein the film includes polymer layers with dissimilar indices of refraction.

6. The method of claim 1 , wherein the multilayer coextrusion and multiplying processes produce a plurality of first polymer layers of a first polymer material and second polymer layers of a second polymer material that are stacked.

7. The method of claim 6 , wherein the first polymer layers and the second polymer layers are randomly stacked and/or the thicknesses of at least some of the plurality of the first polymer layers or the second polymer layers varies between the first polymer layers and the second polymer layers.

8. The method of claim 6 , wherein at least one of the plurality of the first polymer layers or the second polymer layers includes a light absorbing dye.

9. The method of claim 6 , wherein at least one of the plurality of the first polymer layers or the second polymer layers further comprise an organic or inorganic material designed to affect the refractive index of the film.

10. The method of claim 6 , wherein the film comprises about 4 to about 500,000 first polymer layers and second polymer layers.

11. The method of claim 10 , wherein the first polymer layers and the second polymer layers have thicknesses of about 5 nm to about 1 μm.

12. The method of claim 1 , the film comprising a multilayer polymer film.

13. The method of claim 1 , wherein the film added to the object includes a shape memory material that is capable of undergoing at least one environmentally induced shape transition from a temporary shape to a permanent shape after addition of the film to the object, the shape memory material having a first electromagnetic transmission and/or reflection spectrum and/or spectra at the temporary shape and a differing second electromagnetic transmission and/or reflection spectrum and/or spectra at the permanent shape.

14. The method of claim 1 , further comprising providing at least one additional optical security feature on or within the film, the optical feature being recognizable in incident light.

15. The method of claim 14 , wherein the at least one additional optical feature includes a security print, a UV or IR print, a microprint, a layer containing optically variable pigment, a refractive element, a diffractive element, an anisotropic matt structure, a relief hologram, a volume hologram, a zero-order diffraction structure, semi-reflective element, or a thin-film layer element.

16. The method of claim 14 , wherein the at least one additional optical feature includes at least one transmissive diffraction structure which displays different color changing effects when the marking is tilted and/or turned.

17. The method of claim 14 , wherein the object comprises at least one of a bank note, a cheque, a bond, a bank card, a credit card, a cheque card, a currency, a money card, an identification item, an identity item, an access item, an item for granting a permission, an identification card, an identity card, a driving license, a personalized item, a passport, a product, a branded product, a consumer product, a pharmaceutical product, a health product, a nutritional product, a digital content on a data carrier, a software product on a data carrier, a document, a paper document, a security document, a personalized document, a certificate, a share certificate, a certificate of indebtedness, a contract, an insurance policy, a testament, a component, a hardware component, an electronic component, a computer chip, a book, a handbook, a postage stamp, a parking ticket, a transportation ticket, or a ticket for admission to an event.

18. The method of claim 1 , wherein the disordered and/or non-uniform layers are formed by varying polymer layer thicknesses during the multilayer coextrusion and multiplying processes.

19. The method of claim 18 , wherein the polymer layer thicknesses are varied during the multilayer coextrusion and multiplying processes by varying an exit die, using uneven multipliers, and/or using uneven polymer layer multiplication.

20. The method of claim 19 , wherein the polymer layer thicknesses are varied by varying a split ratio of the uneven multipliers or an arrangement of the uneven multipliers.

Assignees

• Univ Case Western Reserve

Inventors

• Baer Eric
• Olah Andy
• Li Zhenpeng
• Hore Michael
• Zhang Cong

Classifications

• H04L9/3278

  using physically unclonable functions [PUF] · CPC title

• G02B6/1225 Primary

  comprising photonic band-gap structures or photonic lattices · CPC title

• G09C1/00 Primary

  Apparatus or methods whereby a given sequence of signs, e.g. an intelligible text, is transformed into an unintelligible sequence of signs by transposing the signs or groups of signs or by replacing them by others according to a predetermined system (cryptographic typewriters G09C3/00) · CPC title

• G02B6/02347

  Longitudinal structures arranged to form a regular periodic lattice, e.g. triangular, square, honeycomb unit cell repeated throughout cladding · CPC title

• H01S5/11

  Comprising a photonic bandgap structure · CPC title