U.S. patent application number 14/520455 was filed with the patent office on 2015-10-08 for method of producing nanoparticle taggants for explosive precursors.
The applicant listed for this patent is The Johns Hopkins University. Invention is credited to John M. Brupbacher, Lisa A. Kelly, Jennifer L. Sample, Morgana M. Trexler, Dajie Zhang.
Application Number | 20150283846 14/520455 |
Document ID | / |
Family ID | 47677723 |
Filed Date | 2015-10-08 |
United States Patent
Application |
20150283846 |
Kind Code |
A1 |
Trexler; Morgana M. ; et
al. |
October 8, 2015 |
METHOD OF PRODUCING NANOPARTICLE TAGGANTS FOR EXPLOSIVE
PRECURSORS
Abstract
A method includes producing an article having a substrate with a
plurality of independent taggant layers that each include metal
oxide nanocrystals doped with at least one Lanthanide element. Each
taggant layer includes metal oxide nanocrystals doped with a
different Lanthanide element than each other taggant layer.
Inventors: |
Trexler; Morgana M.;
(Baltimore, MD) ; Zhang; Dajie; (Baltimore,
MD) ; Kelly; Lisa A.; (Ellicott City, MD) ;
Sample; Jennifer L.; (Bethesda, MD) ; Brupbacher;
John M.; (Baltimore, MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The Johns Hopkins University |
Baltimore |
MD |
US |
|
|
Family ID: |
47677723 |
Appl. No.: |
14/520455 |
Filed: |
October 22, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13566074 |
Aug 3, 2012 |
8895158 |
|
|
14520455 |
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61522035 |
Aug 10, 2011 |
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Current U.S.
Class: |
216/83 |
Current CPC
Class: |
B42D 2035/34 20130101;
Y10T 428/31692 20150401; B42D 25/30 20141001; Y10T 428/31587
20150401; B42D 25/29 20141001; C06B 23/008 20130101; Y10T 428/31609
20150401; C23F 1/00 20130101; Y10T 428/31601 20150401; B41M 3/144
20130101; C23F 4/04 20130101 |
International
Class: |
B42D 25/30 20060101
B42D025/30; C23F 1/00 20060101 C23F001/00; B41M 3/14 20060101
B41M003/14 |
Goverment Interests
STATEMENT OF GOVERNMENTAL INTEREST
[0002] This invention was made with government support under
contract number N00014-05-1-0856 awarded by the Office of Naval
Research (ONR). The government has certain rights in the invention.
Claims
1. A method for the production of a nanoparticle taggant, the
method comprising: creating a printing mold by polishing a
composite of metal and micron fibers to a substantially flat
surface and etching away a portion of the metal from the composite
to expose at least a portion of the micron fibers; applying a
fluorescent ink to the printing mold, said fluorescent ink having
increased intensities in fluorescence and comprising: zirconium
oxide nanocrystals doped in a Lanthanide element; and annealed
metal oxide nanocrystals; and transferring the fluorescent ink from
the printing mold to a substrate.
2. The method of claim 1, wherein the micron fibers comprise
alumina carbide, silicone carbide, titanium carbide, or
combinations thereof.
3. The method of claim 1, wherein a molar concentration of the
Lanthanide element to the metal oxide nanocrystals is between about
3% and about 5%.
4. The method of claim 1, further comprising annealing the annealed
metal oxide nanocrystals at temperatures from about 500.degree. C.
to about 1300.degree. C.
5. The method of claim 1, wherein the annealed metal oxide
nanocrystals comprise a first group of annealed metal oxide
nanocrystals and a second group of annealed metal oxide
nanocrystals, wherein the method further comprises: annealing the
first group of annealed metal oxide nanocrystals at a first
annealing temperature; and annealing the second group of annealed
metal oxide nanocrystals at a second annealing temperature, and the
first annealing temperature is different than the second annealing
temperature.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of co-pending U.S. patent
application Ser. No. 13/566,074, filed Aug. 3, 2012, which claims
priority to and the benefit of prior-filed U.S. Provisional
Application No. 61/522,035, filed on Aug. 10, 2011, now expired,
the entire contents of each of which are hereby incorporated herein
by reference.
BACKGROUND
[0003] Example embodiments generally relate to nanoparticle
taggants and, more particularly, relate to methods for constructing
nanoparticle taggants for application to substrates.
[0004] The issues of authentication and counterfeit deterrence can
be important in many contexts. Bills of currency, stock and bond
certificates, credit cards, passports, driver licenses, as well as
many other legal documents all must be reliably authentic to be
useful. Museums and art galleries face such challenges when
authenticating works of art. Additionally, consumer products and
other articles of manufacturing, such as pharmaceuticals, books,
movies, software, etc., are frequently the subject of
counterfeiting in the form of "pirated" versions or
"knock-offs."
[0005] A wide variety of attempts have been made to limit the
likelihood of counterfeiting. Most such attempts tend to
incorporate a unique identifier, or taggant, into the potentially
counterfeited item. For example, some have utilized fluorescent
compounds as identifiers for these items. Fluorescence occurs when
a material is irradiated with electromagnetic radiation and at
least some is absorbed. The emitted fluorescence can then be read
by suitable means to ensure authenticity.
BRIEF SUMMARY
[0006] Exemplary embodiments of the present invention include an
article having a substrate with a plurality of independent taggant
layers that each include metal oxide nanocrystals that are doped
with at least one Lanthanide element, wherein each taggant layer
includes metal oxide nanocrystals that are doped with a different
Lanthanide element than each other taggant layer.
[0007] In addition, exemplary embodiments of the present invention
include an article having a substrate with a plurality of
independent taggant layers that each include metal oxide
nanocrystals that are doped with at least one Lanthanide element,
wherein each taggant layer includes metal oxide nanocrystals that
are doped at a different molar concentration than each other
taggant layer.
[0008] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrates one or more
embodiments of the invention and, together with the description,
serves to explain the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Having thus described exemplary embodiments of the invention
in general terms, reference will now be made to the accompanying
drawings, which are not necessarily drawn to scale, and
wherein:
[0010] FIG. 1 illustrates a side view of a nanoparticle taggant in
accordance with an example embodiment of the present invention;
and
[0011] FIG. 2 illustrates a side view of a nanoparticle taggant in
accordance with another example embodiment of the present
invention.
[0012] Repeat use of reference characters in the present
specification and drawings is intended to represent same or
analogous features or elements in exemplary embodiments of the
invention.
DETAILED DESCRIPTION
[0013] Some example embodiments now will be described more fully
hereinafter with reference to the accompanying drawings, in which
some, but not all example embodiments are shown. Indeed, the
examples described and pictured herein should not be construed as
being limiting as to the scope, applicability or configuration of
the present disclosure. Rather, these example embodiments are
provided so that this disclosure will satisfy applicable legal
requirements. Like reference numerals refer to like elements
throughout.
[0014] Exemplary embodiments of the present invention relate
generally to nanoparticle taggants for application to various
substrates. As indicated above, taggants, based on their unique
codes, can be used for the authentication of products and
documents, as well as used by brand owners and governments to
authenticate commonly counterfeited items. FIG. 1 illustrates a
side view of a nanoparticle taggant 100 in accordance with an
embodiment of the present invention. As shown, nanoparticle taggant
100 includes a base substrate layer 110, a nanoparticle layer 120,
and a transparent top coating 130.
[0015] The base substrate layer 110 may include any material for
which the application of a nanoparticle taggant is desired. For
example, base substrate layer 110 may include various types of
metals, plastics and polymers, or paper for use in conjunction with
one or more example embodiments of the present invention. By way of
example, in certain embodiments of the invention, base substrate
layer 110 may be constructed of paper to aid in the authentication
of currency. In additional embodiments, base substrate layer 110
may be constructed of various polymers, including high density
polyethylene, for use as labels for pharmaceuticals or other items
that require authentication. The user's specifications will dictate
the necessary material utilized for the base substrate layer
110.
[0016] The nanoparticle layer 120 of one or more example
embodiments of the present invention provides the unique and
non-reproducible or "finger-print" like pattern used for
authentication. The materials utilized for the construction of
nanoparticle layer 120 have unique fluorescent behaviors that, when
excited by a laser, emit fluorescent signals that may be detected
by either a spectrofluorometer or by fluorescence microscopy.
Accordingly, nanoparticle layer 120 may be constructed of any
materials known in the art to produce such unique fluorescent
behavior.
[0017] For example, in some embodiments, nanoparticle layer 120 may
be created from doped metal oxide nanocrystals. Such nanocrystals
include a metal oxide and a dopant comprised of one or more rare
earth elements. In embodiments of the present invention, suitable
metal oxides may include yttrium oxide, zirconium oxide, zinc
oxide, copper oxide, gadolinium oxide, praseodymium oxide,
lanthanum oxide, and combinations thereof. In addition, the dopant
material may include elements from the Lanthanide series (elements
58-71) of the periodic table. Such suitable dopants include, but
are not limited to, europium (Eu), cerium (Ce), neodymium (Nd),
samarium (Sm), terbium (Tb), gadolinium (Gd), holmium (Ho), thulium
(Tm), an oxide thereof, and combinations thereof.
[0018] Any method known in the art may be utilized for the
production of the doped metal oxide nanocrystals. For example, in
some embodiments, a sol-gel process may be utilized where carbon
black may be optionally used as a template in the synthesis.
Further, in additional embodiments, an organometallic reaction may
be utilized.
[0019] The dopant materials are incorporated into the doped metal
oxide nanocrystals in a sufficient amount to permit the doped metal
oxide nanocrystals to be put to practical use in fluorescence
detection as described herein. An insufficient amount may comprise
either too little dopant, which would fail to emit sufficient
detectable fluorescence, or too much dopant, which would cause
reduced fluorescence due to concentration quenching. Accordingly,
in such embodiments where doped metal oxide nanocrystals are
utilized, the molar amount of the dopant material may range from
about 1% to about 10%. In additional embodiments, the molar amount
of the dopant material may range from about 3% to about 5%.
Applicants have found that variations in dopant concentrations may
alter measured characteristics of the nanoparticle materials with
either a spectrofluorometer or a fluorescence microscope, leading
to greater efficiency as a taggant. The particular use of one or
more example embodiments of the present invention may dictate the
necessary atomic concentration utilized.
[0020] Following their preparation, the doped metal oxide
nanocrystals may be annealed. Through such annealing process, the
particle size of the doped metal oxide nanocrystals may be
increased. In particular, Applicants have found that increases in
annealing temperatures have lead to increased intensities in
fluorescence. Such variations in fluorescence, based on the
annealing temperatures, accordingly, may aid in the authentication
processes discussed herein by providing a user with additional
options in creating a unique taggant. In embodiments of the present
invention where the doped metal oxide nanocrystals are annealed,
such annealing may be accomplished at temperatures, in some
embodiments, ranging from about 500.degree. C. to about
1300.degree. C. In additional embodiments, the doped metal oxide
nanocrystals may be annealed at temperatures ranging from about
650.degree. C. to about 1100.degree. C.
[0021] After the materials utilized within the nanoparticle layer
120 have been prepared, any known method in the art may be utilized
for nanoparticle layer's 120 application to base substrate layer
110. For example, in some embodiments, nanoparticle layer 120 may
be sprayed onto base substrate layer 110. In such embodiments, the
doped metal oxide nanocrystals may be in slurry form prior to their
application by spraying. In another embodiment, the doped metal
oxide nanocrystals may be in a powered form and applied in a
"sprinkling" manner over base layer substrate layer 110. The user's
specifications will dictate the necessary application process
utilized.
[0022] Following the application of nanoparticle layer 120,
transparent top coating 130 may be applied to nanoparticle layer
120, opposite base substrate layer 110, as shown in FIG. 1.
Transparent top coating 130 allows for the protection of the
materials utilized in nanoparticle layer 120, yet is made of a
transparent material such that the fluorescence displayed by the
components of nanoparticle layer 120 may be seen. Transparent top
coating 130 may be constructed of any polymer that provides a
substantially clear coating and does not negatively affect the
fluorescent properties exhibited by the nanoparticle layer 120.
Suitable materials for use as transparent top coating may include,
but are not limited to, high density and low density polyethylene,
polypropylene, polyurethane and mixtures thereof. The particular
material utilized for transparent top coating may be based on the
user's specifications.
[0023] Utilizing the example embodiment described above, one or
more example embodiments of the present invention further
contemplate associated methods for providing nanoparticle taggant
100 with unique codes or "fingerprint" like structures for
authentication of various items, including currency and labels for
various products. One such method may include constructing
nanoparticle layer 120 with doped metal oxide nanocrystals having
various atomic ratios. As discussed herein, such alterations in
atomic ratios may be accomplished by varying molar concentrations
of dopant materials within nanoparticle layer 120, and/or by
providing doped metal oxide nanocrystals that utilize various
dopants. As mentioned above, variations in such categories will
provide measured results with numerous "codes", as readings from a
spectrofluorometer or a fluorescence microscope will include
various wavelength readings, various intensity readings, and unique
color fluorescent imaging. Depending on the user's choices for
varying atomic ratios within the parameters described above, a
unique nanoparticle taggant 100, based on readings from the
spectrofluorometer and/or a fluorescence microscope, may be created
that is not easily reproducible. Accordingly, once such taggant has
been created, the readings produced may be stored, and optionally
indexed, for later review of authentic materials by comparing the
stored nanoparticle taggant 100 with the item in question.
[0024] Another method, which may be used alone or in conjunction
with the above-described method, for providing nanoparticle taggant
100 with unique codes may be based on the application of
nanoparticle layer 120 to base layer substrate 110. In many
instances, nanoparticle layer 120 may not completely cover base
layer substrate 110 through the spraying, "sprinkling", or other
suitable application method. As such, base layer substrate 110 will
include unique designs that can be viewed based on the presence of
the above-described fluorescent materials of nanoparticle layer
120, or the absence of such materials and the remaining visible
areas of base layer substrate 110. Because such application process
of nanoparticle layer 120 is random as to its adhesion to base
substrate layer 110, the presence or absence of nanoparticle layer
120 will be unique and non-reproducible for each application.
Accordingly, once such taggant has been created, the readings
produced may be stored, and optionally indexed, for later review of
authentic materials by comparing the stored nanoparticle taggant
100 with the item in question.
[0025] FIG. 2 illustrates a side view of a nanoparticle taggant 200
in accordance with another example embodiment of the present
invention. As shown in the figure, nanoparticle taggant 200 is
constructed of a base substrate layer 210, and an authentication
layer 220. As further shown in the figure, authentication layer 220
includes taggant layers 230. As with the example embodiment
described above, nanoparticle taggant 230 may be used for the
authentication of products and documents, as well as being used by
brand owners and governments to authenticate commonly counterfeited
items. As such, base substrate layer 210 may be constructed and
selected in the same manner as base substrate layer 110.
[0026] As shown in FIG. 2, authentication layer 230 includes
multiple taggant layers 230. Taggant layers 230 provide
nanoparticle taggant 200 with the unique code for authenticating
certain items by creating a "barcode-like" design that is not
easily reproducible and can be viewed by a spectrofluorometer
and/or a fluorescence microscope. Taggant layers 230 may be
constructed of various polymers and/or glass including, but not
limited to, high density and low density polyethylene,
polypropylene, polyurethane and mixtures thereof, with varying
thicknesses from about 0.01 .mu.m to about 10 .mu.m. In addition,
although nanoparticle taggant 200 is shown with four taggant layers
230, any number of taggant layers may be utilized, for example,
two, three, four, five, and six or more taggant layers 230 may be
used in association with nanoparticle taggant 200. As will be
appreciated by those skilled in the art, the addition of more
taggant layers may allow the user to provide an even more unique
taggant, accordingly, the user's preferences will dictate the
discussed variations of taggant layers 230.
[0027] To provide taggant layers 230 with their unique codes,
taggant layers 230 further include materials known in the art to
produce the unique fluorescent behavior as exhibited by
nanoparticle layer 120 of the example embodiment described above.
Suitable materials for taggant layers include those mentioned
above, as well as their method of production, dopant
concentrations, etc. In addition, the fluorescent materials may
also be applied to taggant layers 230 by the use of any suitable
techniques, including, but not limited to, spraying, "sprinkling"
from a powered form and doping.
[0028] Utilizing the example embodiment described above, additional
embodiments of the present invention further include associated
methods for utilizing nanoparticle taggant 200. One such method may
include constructing each taggant layer 230 with doped metal oxide
nanocrystals having various atomic ratios by, as indicated above,
varying molar concentrations of dopant materials within each
taggant layer, and/or by providing doped metal oxide nanocrystals
on each taggant that utilize various dopants. As such, each taggant
layer 230 will have a unique reading from a spectrofluorometer
and/or a fluorescence microscope. Accordingly, the combination of
readings from all taggant layers will be unique and not easily
reproducible. After which, the readings produced may be stored, and
optionally indexed, for later review of authentic materials by
comparing the stored nanoparticle taggant 200 with the item in
question.
[0029] Another method, which may be used alone or in conjunction
with the above-described method, for providing nanoparticle taggant
200 with unique codes may be based on the application of the
fluorescent material to taggant layers 230. As discussed with the
example embodiment described above, the fluorescent materials may
not completely cover taggant layers 230 through spraying,
"sprinkling", or other suitable application method. As such,
taggant layers 230 will include unique designs that can be viewed
based on the presence of the above-described fluorescent materials,
or the absence of such materials and the remaining visible areas of
taggant layers 230. Because such application process of fluorescent
materials is random as to its adhesion to taggant layers 230, the
presence or absence of such fluorescent materials will be unique
and non-reproducible for each application. Again, the use of
multiple taggant layers 230 may aid in creating an even more unique
taggant, as additional patterns of fluorescent materials may be
present. Again, once nanoparticle taggant 200 has been created, the
readings produced may be stored, and optionally indexed, for later
review of authentic materials by comparing the stored nanoparticle
taggant 200 with the item in question.
[0030] Yet another example embodiment includes a mold and
fluorescent ink for the production of a taggant. In such
embodiments, a mold may be fabricated from the composite of micron
fibers and metal. Suitable micron fibers for use in one or more
example embodiments of the present invention may include, but are
not limited to, alumina carbide, silicone carbide, titanium
carbide, combinations thereof and others, where the fibers include
a diameter from about 1 to about 20 microns in diameter, or from
about 5 to about 10 microns in diameter. In addition, the metal
utilized in one or more example embodiments of the present
invention for the construction of the mold may include aluminum,
nickel, tin, lead, zinc, combinations thereof, and others. Once a
suitable composite is selected, the composite may be polished by
any suitable means to arrive at a substantially flat surface. After
which, a portion of the composite may be etched away, by any
suitable means, such that a portion of the micron fibers are
exposed. The random orientations of the remaining micron fibers
form a suitable mold that is not easily reproducible and is
suitable for use as a taggant.
[0031] The fluorescent ink utilized in the example embodiment
described above may be constructed from any of the doped metal
oxide nanocrystals mentioned above. The ink may be created by the
doped metal oxide nanocrystals' dispersion in a water bath that may
include surfactants, for example, abietic acid, diglyceride and
others, as well as other stabilizing agents, including, but not
limited to acetic acid, formic acid, uric acid, and others. Once a
fluorescent ink has been created, it may be placed within the mold
for transferring the fluorescent ink to a substrate like those
contemplated for base substrate layers 110 and 210 as discussed
above. In addition, after the ink has been transferred to the
substrate, a transparent top coating, like that contemplated with
respect to the example embodiment described above, may be applied
to the ink. Such transparent top coating may aid in maintaining the
orientation of the ink in the molded configuration.
[0032] Utilizing the example embodiment described above, the
present invention further includes associated methods for utilizing
the mold and fluorescent inks as a taggant. As indicated above, the
uniqueness of the mold allows for the imprint of ink to a suitable
substrate to be utilized in a method of authenticating an item.
Accordingly, after the ink has been transferred to a suitable
substrate, the unique design on the ink may be stored and
optionally indexed, for later review of authentic materials by
comparing the stored design with the item in question.
[0033] In addition, another suitable method that can be utilized
together with the above-described method or independently, includes
constructing the fluorescent ink with doped metal oxide
nanocrystals having various atomic ratios. As indicated above, this
may be accomplished by varying molar concentrations of dopant
materials within the ink and/or by providing doped metal oxide
nanocrystals that utilize various dopants. As such, the fluorescent
ink printed to the substrate will have a unique reading from a
spectrofluorometer and/or a fluorescence microscope. After which,
the readings produced may be stored, and optionally indexed, for
later review of authentic materials by comparing the stored design
with the item in question.
[0034] Many modifications and other embodiments of the inventions
set forth herein will come to mind to one skilled in the art to
which these inventions pertain having the benefit of the teachings
presented in the foregoing descriptions and the associated
drawings. Therefore, it is to be understood that the inventions are
not to be limited to the specific embodiments disclosed and that
modifications and other embodiments are intended to be included
within the scope of the appended claims. Moreover, although the
foregoing descriptions and the associated drawings describe
exemplary embodiments in the context of certain exemplary
combinations of elements and/or functions, it should be appreciated
that different combinations of elements and/or functions may be
provided by alternative embodiments without departing from the
scope of the appended claims. In this regard, for example,
different combinations of elements and/or functions than those
explicitly described above are also contemplated as may be set
forth in some of the appended claims. In cases where advantages,
benefits or solutions to problems are described herein, it should
be appreciated that such advantages, benefits and/or solutions may
be applicable to some example embodiments, but not necessarily all
example embodiments. Thus, any advantages, benefits or solutions
described herein should not be thought of as being critical,
required or essential to all embodiments or to that which is
claimed herein. Although specific terms are employed herein, they
are used in a generic and descriptive sense only and not for
purposes of limitation.
* * * * *