Nanocrystal taggants
First Claim
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1. A method of encoding and authenticating a nanocrystal spectral code, the method comprising:
- providing a composition comprising a population of nanocrystals that emit light when excited, the population comprising two or more different subsets of nanocrystals wherein each subset comprises a plurality of quantum dots of the same size and/or the same composition;
determining one or more optical properties of the composition when excited with one or more select excitation wavelengths to encode a unique spectral code for the composition, the unique spectral code comprising at least one optical property defined by the interaction of optical properties of at least two of the two or more different subsets of nanocrystals, wherein the interaction comprises an interaction between the emission frequency of at least the first said subset and the emission frequency of at least the second said subset;
tagging at least a first object with the composition;
exciting the first object and/or a second tagged object with the one or more select excitation wavelengths;
detecting emission wavelengths emitted from the composition of nanocrystals on the first and/or second tagged object; and
determining whether the first or second tagged object has the unique spectral code;
wherein said step of determining one or more optical properties occurs before said tagging step, and said tagging step occurs before said step of determining whether the object is tagged with the spectral code.
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Abstract
The compositions, methods and systems of the invention provide nanocrystal taggants for unobtrusive monitoring of objects. Objects can be tagged with nanocrystal taggant compositions for detection of informative invisible emissions on illumination with appropriate excitation wavelengths. Authentication schemes are also provided that takes advantage of the unique emission and absorption characteristics of nanocrystals to create a unique spectral code that is far more difficult to decode and replicate than those previously employed.
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Citations
21 Claims
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1. A method of encoding and authenticating a nanocrystal spectral code, the method comprising:
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providing a composition comprising a population of nanocrystals that emit light when excited, the population comprising two or more different subsets of nanocrystals wherein each subset comprises a plurality of quantum dots of the same size and/or the same composition; determining one or more optical properties of the composition when excited with one or more select excitation wavelengths to encode a unique spectral code for the composition, the unique spectral code comprising at least one optical property defined by the interaction of optical properties of at least two of the two or more different subsets of nanocrystals, wherein the interaction comprises an interaction between the emission frequency of at least the first said subset and the emission frequency of at least the second said subset; tagging at least a first object with the composition; exciting the first object and/or a second tagged object with the one or more select excitation wavelengths; detecting emission wavelengths emitted from the composition of nanocrystals on the first and/or second tagged object; and determining whether the first or second tagged object has the unique spectral code; wherein said step of determining one or more optical properties occurs before said tagging step, and said tagging step occurs before said step of determining whether the object is tagged with the spectral code. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of encoding and authenticating a nanocrystal spectral code, the method comprising:
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providing a composition comprising a population of nanocrystals that emit light when excited, the population comprising two or more different subsets of nanocrystals wherein each subset comprises a plurality of quantum dots of the same size and/or the same composition; determining one or more optical properties of the composition when excited with one or more select excitation wavelengths to encode a unique spectral code for the composition, the unique spectral code comprising a first emission wavelength of a first nanocrystal subset and a second emission wavelength of a second nanocrystal subset, wherein the first and second emission wavelengths are the same; tagging at least a first object with the composition; exciting the first object and/or a second tagged object with the one or more select excitation wavelengths; detecting one or more emission wavelengths and the corresponding emission intensity of light emitted from the composition of nanocrystals on the first and/or second tagged object; and determining whether the first and/or second tagged object has the unique spectral code; wherein said step of determining one or more optical properties occurs before said tagging step, and said tagging step occurs before said step of determining whether the object is tagged with the spectral code.
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Specification