U.S. patent application number 13/777034 was filed with the patent office on 2013-09-12 for anodized titanium devices and related methods.
The applicant listed for this patent is John Disegi. Invention is credited to John Disegi.
Application Number | 20130233717 13/777034 |
Document ID | / |
Family ID | 47843439 |
Filed Date | 2013-09-12 |
United States Patent
Application |
20130233717 |
Kind Code |
A1 |
Disegi; John |
September 12, 2013 |
Anodized Titanium Devices and Related Methods
Abstract
The present disclosure provides, inter alia, devices that
include a film of antimicrobial titanium oxide. This film may be
anatase phase and may be of sufficient thickness to confer a
visually perceptible color on the devices. The devices may be
implants, supports, or even fasteners. Also provided are methods of
fabricating such devices, as well as kits that feature the
disclosed devices.
Inventors: |
Disegi; John; (West Chester,
PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Disegi; John |
West Chester |
PA |
US |
|
|
Family ID: |
47843439 |
Appl. No.: |
13/777034 |
Filed: |
February 26, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61606152 |
Mar 2, 2012 |
|
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|
Current U.S.
Class: |
205/50 ;
205/322 |
Current CPC
Class: |
C25D 11/26 20130101;
C25D 7/00 20130101; A61L 31/022 20130101; A61L 31/16 20130101; A61L
2300/404 20130101; A61L 2400/18 20130101; A61L 2300/102
20130101 |
Class at
Publication: |
205/50 ;
205/322 |
International
Class: |
C25D 11/26 20060101
C25D011/26; C25D 7/00 20060101 C25D007/00 |
Claims
1. A medical device, comprising: a substrate comprising titanium
and a titanium oxide film surmounting at least a portion of the
titanium, at least a portion of the titanium oxide film being
anatase phase, and the titanium oxide film being of such a
thickness so as to impart a visually perceptible color to the
medical device.
2. The medical device of claim 1, wherein the substrate comprises
essentially pure titanium.
3. The medical device of claim 1, wherein the substrate comprises a
titanium alloy.
4. The medical device of claim 1, further comprising a core
underlying the substrate.
5. The medical device of claim 4, wherein the core comprises a
polymer.
6. The medical device of claim 1, wherein the titanium oxide film
is characterized as anodized.
7. The medical device of claim 1, wherein the thickness of the
titanium oxide film is in the range of from about 20 nm to about
500 nm.
8. The medical device of claim 1, wherein the medical device is
configured as an implant, a needle, a catheter, or any combination
thereof.
9. The medical device of claim 8, wherein the medical device is
configured as an implant.
10. The medical device of claim 1, wherein the film comprises more
than about 95% anatase titanium oxide.
11. The medical device of claim 1, wherein the substrate comprises
an admixture of a polymer and titanium.
12. A method of processing a medical device, comprising: contacting
a substrate material comprising titanium with an electrolyte;
anodizing the substrate material so as to give rise to film of
titanium oxide surmounting at least a portion of the substrate
material
13. The method of claim 12, wherein the electrolyte comprises an
acid.
14. The method of claim 13, wherein the acid is between about 0.5 M
to about 7.0 M.
15. The method of claim 14, wherein the acid comprises sulfuric
acid.
16. The method of claim 12, wherein the titanium oxide film has a
thickness in the range of from about 20 nm to about 500 nm.
17. The method of claim 12, further comprising exposing the film to
illumination having a wavelength in the range of between about 350
nm to about 380 nm.
18. A kit, comprising: first and second devices, each of the
devices having at least one surface that is at least partially
surmounted by a film of titanium oxide, that is at least partially
anatase in phase and that confers a visually perceptible color on
the devices, and the first and second devices differing in at least
one other physical characteristic.
19. The kit of claim 18, wherein the first and second devices
differ in visually perceptible color.
20. The kit of claim 18, further comprising a source of light being
operable to emit light of a wavelength and intensity sufficient to
cause the titanium dioxide to exhibit a biocidal effect upon
irradiation with light from the light source.
21. The kit of claim 18, further comprising a removable package
that is essentially transparent to ultraviolet light, the first,
second, or both devices being disposed within the removable
package.
22. The kit of claim 20, wherein the light comprises a wavelength
of between about 350 nm and about 380 nm.
Description
RELATED APPLICATION
[0001] The present application claims priority to U.S. application
61/606,152, "Anodized Titanium Devices and Related Methods," filed
Mar. 2, 2012, the entirety of which application is incorporated
herein by reference for any and all purposes.
TECHNICAL FIELD
[0002] The present disclosure relates to the field of biomechanical
implants and to the field of anodized metals.
BACKGROUND
[0003] Because of its high strength, low weight, and corrosion
resistance, titanium has application to various medical implant
applications. Because unwanted microbial growth is a concern in
medical implant technology, some have attempted to construct
titanium implants that feature titanium oxide coatings. Such
coatings, however, suffer from poor adhesion to the underlying
implant structure, are prone to delamination, and are also
associated with a significant reduction in fatigue strength.
Accordingly, there is a long-felt need in the art for titanium
implant structures that have antimicrobial properties that do not
suffer from the drawbacks of titanium oxide coated implant
materials. There is also a related need in the field for related
methods of fabricating such implants.
SUMMARY
[0004] This disclosure presents, inter alia, methods to produce and
activate an antimicrobial oxide surface on titanium implants. As
discussed further herein, electrochemical anodization parameters
such as waveform and electrolyte may be controlled to produce an
anatase titanium oxide surface morphology. Such morphology is
particularly useful in antimicrobial applications as compared to
rutile, brookite, or amorphous titanium oxide surface
structures.
[0005] The surface oxide film may be heat treated to transform the
surface structure or to optimize the percentage (%) anatase in the
surface film. Anatase titanium oxide demonstrates antimicrobial
properties when activated under specific photocatalytic conditions.
Antimicrobial activation of the anatase titanium oxide can occur in
the near ultraviolet wavelength of 350 to 380 nm to create reactive
oxygen species and hydroxyl radicals that provide antimicrobial
properties. The titanium implant may be activated before the
titanium implant is packaged or, alternatively, may be packaged in
the operating room before implantation using a suitable light
source.
[0006] A further advantage of the disclosed methods and implants is
the ability to provide color coded titanium implants. This color
coding may be used to construct an implant system (e.g.,
color-coded by size, shape, by application, or even by patient
type) that also features antimicrobial properties when activated.
The anodized film may be thin (in the nanometer range), and because
the film is produced by electrochemical oxidation, the anatase film
is extremely adherent, durable, and exhibits negligible reduction
in fatigue strength for the implant.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The summary, as well as the following detailed description,
is further understood when read in conjunction with the appended
drawings. For the purpose of illustrating the invention, there are
shown in the drawings exemplary embodiments of the invention;
however, the invention is not limited to the specific methods,
compositions, and devices disclosed. In addition, the drawings are
not necessarily drawn to scale or proportion. In the drawings:
[0008] FIG. 1 illustrates the x-ray crystallography spectrum for an
exemplary anatase-phase material according to the present
disclosure, showing the anatase phase present in the material;
[0009] FIG. 2 illustrates an exemplary setup for fabricating an
anatase film on the surface of a titanium substrate;
[0010] FIG. 3 illustrates several colored anatase samples according
to the present disclosure;
[0011] FIG. 4 illustrates an additional composite image of the
different voltage levels we tested in a 0.5 molar sulfuric acid
bath with a square wave (DC);
[0012] FIG. 5 illustrates x-ray diffraction data for the samples of
FIG. 4, with the anatase peak labeled;
[0013] FIG. 6 presents the same x-ray diffraction data with the
rutile peak labeled;
[0014] FIG. 7 illustrates a composite image of samples tested in a
0.94 molar sulfuric acid bath (square wave DC);
[0015] FIG. 8 presents x-ray diffraction data from the samples of
FIG. 7 with the anatase peak labeled; and
[0016] FIG. 9 presents x-ray diffraction data from sputter-coated
materials as compared to a sample (top graph) according to the
present disclosure, with the anatase peak in the topmost sample
labeled.
[0017] FIG. 10 presents an SEM image showing the natural forming
oxide of titanium;
[0018] FIG. 11 presents an SEM image showing the titanium oxide
after pickling in an exemplary nitric-hydrofluoric acid
solution;
[0019] FIG. 12 presents a comparatively low magnification SEM image
of a gold anodized titanium sample tested in 0.5 M H2SO4;
[0020] FIG. 13 presents a comparatively higher magnification SEM
image of a gold anodized titanium sample tested in 0.5 M H2SO4;
[0021] FIG. 14 presents a higher magnification SEM image of a gold
anodized titanium sample tested in 0.5 M H2SO4;
[0022] FIG. 15 presents a low magnification SEM image of a gold
anodized titanium sample tested in 2 M H2SO4;
[0023] FIG. 16 presents a high magnification SEM image of a gold
anodized titanium sample tested in 2 M H2SO4;
[0024] FIG. 17 presents a high magnification SEM image of a gold
anodized titanium sample tested in 2 M H2SO4;
[0025] FIG. 18 presents a low magnification SEM image of a green
anodized titanium sample tested in 0.94 M H2SO4;
[0026] FIG. 19 presents a high magnification SEM image of a green
anodized titanium sample tested in 0.94 M H2SO4;
[0027] FIG. 20 presents a high magnification SEM image of a green
anodized titanium sample tested in 0.94 M H2SO4;
[0028] FIG. 21 presents a low reproduction SEM image obtained with
the EBSD detector showing the area being scanned of the 0.94 M
green anodized titanium;
[0029] FIG. 22 presents a grain orientation map and associated
inverse pole figure map for the 0.94 M green anodized titanium;
[0030] FIG. 23 presents an EBSD image showing the crystalline
phases detected and associated area fractions for the 0.94 M green
anodized titanium;
[0031] FIG. 24 presents an x-Ray diffraction scan of a green
anodized titanium sample tested in 2 M H2SO4;
[0032] FIG. 25 presents a low magnification SEM image of a green
anodized titanium sample tested in 2 M H2SO4;
[0033] FIG. 26 presents a high magnification SEM image of a green
anodized titanium sample tested in 2 M H2SO4;
[0034] FIG. 27 presents a high magnification SEM image of a green
anodized titanium sample tested in 2 M H2SO4;
[0035] FIG. 28 presents an SEM image obtained with the EBSD
detector showing the area being scanned of the 2 M green anodized
titanium;
[0036] FIG. 29 presents an EBSD image showing the grain
orientations and associated inverse pole figure map for the 2 M
green anodized titanium;
[0037] FIG. 30 presents an EBSD image showing the crystalline
phases detected and associated area fractions for the 2 M green
anodized titanium; and
[0038] FIG. 31 presents an x-Ray diffraction scan of a green
anodized titanium sample tested in 2 M H2SO4.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0039] The present disclosure may be understood more readily by
reference to the following detailed description taken in connection
with the accompanying figures and examples, which form a part of
this disclosure. It is to be understood that this disclosure is not
limited to the specific devices, methods, applications, conditions
or parameters described and/or shown herein, and that the
terminology used herein is for the purpose of describing particular
embodiments by way of example only and is not intended to be
limiting. Also, as used in the specification including the appended
claims, the singular forms "a," "an," and "the" include the plural,
and reference to a particular numerical value includes at least
that particular value, unless the context clearly dictates
otherwise. The term "plurality", as used herein, means more than
one. When a range of values is expressed, another embodiment
includes from the one particular value and/or to the other
particular value. Similarly, when values are expressed as
approximations, by use of the antecedent "approximately" or
"about," it will be understood that the particular value forms
another embodiment. All ranges are inclusive and combinable, and
all documents cited herein are incorporated by reference in their
entireties for any and all purposes.
[0040] It is to be appreciated that certain features of the
disclosure which are, for clarity, described herein in the context
of separate embodiments, may also be provided in combination in a
single embodiment. Conversely, various features of the disclosure
that are, for brevity, described in the context of a single
embodiment, may also be provided separately or in any
subcombination. Further, reference to values stated in ranges
include each and every value within that range.
[0041] In a first aspect, the present disclosure provides medical
devices. These devices may be configured as, e.g., implants,
supports, fasteners, and the like.
[0042] The medical devices suitably first include a substrate
comprising titanium. The substrate may be solid titanium (e.g., a
solid titanium rod, sheet, plate, and the like), but may also
include a titanium coating or shell associated with a core
material. As one example, the device may include a core that is
surmounted by a titanium (pure, alloy, or even composite) coating.
The titanium coating may be bonded to the core or mechanically
affixed or otherwise interlocked with the core. A device according
to the present disclosure may feature an exterior that has a region
of titanium, titanium alloy, or of titanium composite, and another
region that is free of titanium. Such devices are suitable for
applications where the titanium-bearing portion is implanted into a
subject's body, and the non-titanium bearing portion lies outside
of the subject.
[0043] The core may be polymeric or other material (e.g., metal)
that is adaptable to use in medical implants. Exemplary polymers
include PEEK, PEKK, UHMWPE, poyphenylsulfone, HDPE, PCU, and the
like. PE, PP, and PC may also be used.
[0044] The devices suitably include a titanium oxide film that
surmounts at least a portion of the titanium of the device, with at
least a portion of the titanium oxide film suitably being anatase
phase. The film may be anodized in form. The titanium oxide film is
suitably of such a thickness so as to impart a visually perceptible
color to the medical device.
[0045] The substrate may, as described above be essentially pure
titanium. The substrate may be solid titanium (e.g., a solid rod,
plate, or platelet). Alternatively, the substrate may comprise a
titanium alloy. Virtually any implantable titanium alloys may be
used in the disclosed devices. A partial, nonexhaustive listing of
such alloys includes, e.g., Ti6Al7Nb, Ti6Al4V, Ti6Al4V ELI, Ti15Mo,
Ti13Nb13Zr, Ti3Al2.5V, and Ti12Mo6Zr2Fe. The implantable alloys may
be anodized and will suitably contain a % of anatase in the mixed
oxide film. For example, an anodized Ti6Al7Nb substrate is
comprised of titanium oxide plus aluminum oxide plus niobium oxide
and will contain less anatase than a pure titanium substrate. The
specific anodizing parameters required to produce an anatase
titanium oxide structure will also vary for each alloy and will
affect the amount of anatase that is present in the mixed oxide
film. The devices may feature apertures (smooth or threaded) to
facilitate installation of the devices into a subject. For example,
a support plate used to support a broken long bone implant may
feature smooth apertures at either end, through which screws or
other fasteners may be installed to fix the plate to the long bone.
The fasteners themselves may, as described elsewhere herein,
feature anatase regions according to the present disclosure so as
to render the fasteners antimicrobial. The fasteners may also
feature a color that matches that of the support plate so as to
indicate to the user that the fasteners are adapted for use with
the plate.
[0046] The thickness of the film may vary, depending on the needs
of the user and the desired color profile. The thickness is
suitably in the range of from about range of 20 nm to about 500 nm,
or from 100 nm to about 400 nm, or even from about 130 nm to about
275 nm. These thicknesses enable the production of devices that
exhibit colors of, e.g., gold, rose red, purple, aqua, and green,
among others. Other colors, such as bronze, brown, dark purple,
blue, light blue, green-gray, and light green may also be produced
by modulating the thickness of the anatase coating.
[0047] A device according to the present disclosure may include a
first region that features a film of one thickness and another
region that features a film of another thickness. In this way, a
device may include two or more regions that feature different
colors. This may be used so as to inform the user as to the
alignment of the device when in use. For example, a device may be
configured to have a blue distal region and a green proximal
region. The disclosed devices may also be configured such that a
colored region on an implant (e.g., blue) coordinate with the
fasteners (blue screws, nails, etc.) that are to be used with that
implant.
[0048] The devices may be configured to serve in a variety of
applications. In some embodiments, the devices are adapted to serve
as implants. The implants may be suitable for long bone implant
purposes or for implantation as other bones. The implants may be
configured as plates, strips, ribbons, or the like. Alternatively,
the implants may be configured as needles, catheters, cannulas, or
even as other instruments such as scoops, rasps, and the like.
Implant configurations are considered especially suitable, as such
configurations are capable of taking advantage of the antimicrobial
characteristics of the disclosed materials. The disclosed devices
may also be applied as total joints (hips, wrists, shoulders,
ankles, knees, spinal disc prostheses, arthoplasty devices, and the
like). The disclosed devices may also be applied as plates, screws,
pins, intramedullary nails, neurological implants, mandibular
implants, mid-face implants, spinal rods, spinal clamps,
intervertebral cages, and the like.
[0049] The films of the disclosed devices suitably comprise a
content that is suitably more than 95% anatase for commercially
pure ("CP") titanium. The film may be more than about 5%, 15%, 25%,
35%, 45%, 55%, 65%, 75%, 85 A anatase phase. In embodiments where
titanium alloys are used, the device film may be less than 95%
anatase, depending on the composition of the mixed oxide film
composition after anodizing. In certain embodiments, the titanium
oxide film includes greater than 95% anatase and less than about 5%
rutile phase. Without being bound to any single theory, the anatase
titanium oxide film can be described as a cohesive single-phase
oxide that exhibits a distinct crystallographic X-Ray structure, as
shown in FIG. 1, which figure illustrates the anatase phase present
in a sample according to the present disclosure.
[0050] The substrate may, in some embodiments, be a mixture of a
polymer and titanium. Such composites may include a polymer
composition combined with titanium or titanium alloy. The polymer
component of the substrate may be a single polymer (e.g., PEEK), or
multiple polymers (e.g., PEEK and PP) or even a copolymer. The
substrate may comprise a mixture of titanium bodies (particles,
flakes, and the like) dispersed within or on the bulk of a polymer
or other matrix. The film may be integral to the device.
[0051] Also provided are methods of fabricating medical devices.
These methods suitably include contacting a substrate material
comprising titanium with an electrolyte and anodizing the substrate
material by exposing the substrate material to a voltage so as to
give rise to film of titanium oxide surmounting at least a portion
of the substrate material.
[0052] The applied voltage is suitably in the range of from about
25 V to about 400 V, or from about 50 V to about 350 V, or from
about 200 V to about 250 V. The voltage may be applied in
intervals. The voltage may increase over time, or may be applied at
a constant level. The voltage may be increased over time. The
increase may be linear, exponential, or step-wise. The voltage may
also have a sine waveform, square waveform, triangle, or sawtooth
waveform.
[0053] In one exemplary embodiment, devices were fabricated using a
DC rectifier. The voltage was applied with a 10 volt incremental
increase every 10 seconds. A programmable square wave waveform was
used, with an on-time of 1-5 micro seconds and an off time 99
microseconds. The electrolyte used was a 0.94 M sulfuric acid with
a bath pH of about 0.15 at room temperature. Other suitable
electrolytes investigated were 0.5M sulfuric acid (pH 0.30), 0.94 M
sulfuric acid (pH 0.15), and 2.0 M sulfuric acid (pH -0.30). 6.0 M
sulfuric acid is also a suitable electrolyte, as such an
electrolyte is capable of producing a comparatively high percentage
of anatase in the color anodized film. Electrolytes--e.g., sulfuric
acid--at from about 0.3 M to about 7.0 M or even 9.0 M (e.g., 2.8
M, 3.8 M, 5.6 M, and 6.0 M) are considered especially suitable for
the disclosed techniques.
[0054] The electrolyte may be a salt solution, or an acid solution.
Various salts (sodium chloride, calcium chloride, and the like) may
be used. Various acids may be used in the electrolyte, such as
acetic, citric, nitric, sulfuric, and other acids may be used. An
electrolyte may, for example, comprise a mixture of ACS grade
nitric acid (67-70%) and distilled water.
[0055] The user may clean or otherwise pretreat ("pickle") the
titanium before processing, as desired. A variety of methods may be
used to clean the titanium. For example, one may clean the titanium
by scrubbing or brushing with a wire or other brush. Grinding, draw
filing, and acid picking may also be used. Various combinations of
nitric acid plus hydorfluoric acid may be used as long as the
volume % nitric acid to volume % hydrofluoric acid ratio is greater
than 10:1 to minimize the occurrence of hydrogen embrittlement. One
may also use a water rinse to remove acid, followed by a hot water
rinse to facilitate drying. Another exemplary pretreatment can be a
nitric acid-hydrofluoric acid solution (e.g., 20:2 ratio) Immersion
in nitric-hydrofluoric acid solution is used to clean and activate
the titanium surface before electrolytic anodization. The ratio of
nitric acid to hydrofluoric acid may be adjusted so as to avoid
hydrogen pickup in the titanium material. A nitric acid to
hydrofluoric acid ratio of minimum ca. 10 to 1 to minimize hydrogen
absorption during acid treatment is recognized in ASTM B600
Standard Guide for Descaling and Cleaning Titanium and Titanium
Alloy Surfaces.
[0056] A user may also apply an activation process to configure the
titanium film for antimicrobial activity. Without being bound to
any single theory, anatase activation may be effected by the near
ultraviolet wavelength of 350 to 380 nanometers so as to create
reactive oxygen species and hydroxyl radical that provide
antimicrobial properties.
[0057] In one exemplary embodiment, titanium implants or coupons
are cleaned in an alkaline bath or detergent to remove oil, cutting
fluid, and other loose surface contaminants The implants are then
immersed in a nitric acid-hydrofluoric acid pre-treatment solution
(e.g., 20:2 ratio). Implants are then placed in a titanium basket
or a clamping device in contact with a copper bus bar that
connected to a DC rectifier power supply, as illustrated in FIG. 2.
The clamped implant or basket was immersed in a 0.94 M sulfuric
acid electrolyte and the voltage was increased in 10 volt
incremental increase every 10 seconds.
[0058] As shown in FIG. 2, a power supply may be connected through
the negative lead (anode) to conductive (e.g., copper) bars running
across the short lengths (side to side) of the anodizing bath to
carbon counter electrodes. The exemplary negative lead shown here
is split into two cables for this setup with two carbon counter
electrodes on each anode copper bar. The power supply is also
connected through the positive (cathode) lead to a copper bar that
runs across the length of the anodizing bath as shown in FIG. 2.
The positive lead is connected directly to the cathode copper bar
and the samples are in turn connected through a metallic clamp, and
the samples are then suspended in the electrolyte.
[0059] The carbon counter electrodes are spaced out evenly from one
another in order to give the most efficient anode to cathode area
in the electrolyte (the most efficient flow of electrons in
solution). Alternatively, the positive lead from the power supply
could be connected to the cathode bar(s) and the negative lead
connected to the anode bar(s). The power (voltage and amperage) of
the power supply, number and spacing of counter electrodes, and
number of cathode bars would depend on the size of the anodizing
bath.
[0060] Processed titanium coupons are shown in FIG. 3. At the upper
left of the figure, a coupon with a yellow-gold color is shown.
This coupon was produced by processing at 75 V. The second coupon
from the upper left exhibited a pink-rose color, and was processed
at 85 V. The third coupon from the upper left exhibited a violet
color, which coupon was processed at 95 V. The coupon fourth from
the upper left (processed at 105 V) exhibited an aqua blue color.
The coupons in the lower row, from left to right respectively,
exhibited blue (115 V), blue-green (125 V), medium green (150 V),
green (200 V), and light green (300 V) colors.
[0061] The foregoing samples were produced using a waveform with a
time increment step size of 10 seconds and a voltage step size of
5, 10 or 20V; other voltage steps of from 0.01 V to 50 V are also
suitable. The voltage step size was limited to the inputs on the
current power supply which had only 15 steps available; this should
not be understood as limiting the present disclosure in any way.
Thus, the final voltages of 150V and less were increased at 10V
every 10 seconds and final voltages of >150V are stepped up at
20V every 10 seconds. Also any final voltage not an integer of 10
had a 5V end step for 10 seconds. For example, a final voltage of
70V would have a recipe of 10V 10 sec, 20V 10 sec, 30V 10 sec, 40V
10 sec, 50V 10 sec, 60V 10 sec, and 70V 10 sec. A 75V final voltage
would have a recipe of 10V 10 sec, 20V 10 sec, 30V 10 sec, 40V 10
sec, 50V 10 sec, 60V 10 sec, 70V 10 sec, and 75V 10 sec. Another
example is for a final voltage of 200V which is 20V 10 sec, 40V 10
sec, 60V 10 sec, 80V 10 sec, 100V 10 sec, 120V 10 sec, 140V 10 sec,
160V 10 sec, 180V 10 sec, and 200V 10 sec. The 10 second durations
of these voltages is not limiting, as voltages may be applied for
from about 0.01 seconds to about 10, about 20, about 30, about 60,
about 120, about 300, or even about 500 seconds.
[0062] The output color is related to the thickness of the surface
oxide created. The oxide layer created depends on the final voltage
applied, the area of the sample exposed to the electrolyte (current
density, A/cm.sup.2), and also sample surface condition. Current
for the exemplary system was set at 10 amps and the area suspended
in the electrolyte was constant for all samples. Further, all
samples were prepared for anodization using the same techniques
previously described. Therefore, the only variable that changed
color (oxide thickness) was the final applied voltage. Without
being bound to any particular theory, exposure time at the final
voltage may noe necessarily change (purple to green for example)
the final color of the surface oxide and will be in the range of
the corresponding thickness values given in the following table,
which table relates exemplary surface oxide thicknesses (given in
nm) to surface color appearance: [0063] Bronze: 10-25 [0064] Brown:
25-40 [0065] Dark Purple : 40-50 [0066] Blue: 50-65 [0067] Light
Blue: 75-100 [0068] Green Gray: 100-115 [0069] Light Green: 110-125
[0070] Gold: 135-150 [0071] Rose Red: 150-165 [0072] Purple:
160-200 [0073] Aqua: 230-250 [0074] Green: 250-275
[0075] Additional, exemplary samples are shown in FIG. 4. The
samples in that figure were as follows: 70V (yellow-green), 90V
(pink-rose), 110V (blue), 115 (blue-violet), 120V (green), 130V
(green), 140V (medium green).
[0076] FIG. 5 presents x-ray diffraction spectra for the samples
shown in FIG. 4. As shown in the figure, each of the samples
presents a characteristic anatase peak at a two-theta value of
about 25.25 degrees. FIG. 6 presents x-ray diffraction data for the
samples shown in FIG. 4 and FIG. 5, with the location of the
characteristic rutile peak (not present in the samples)
labeled.
[0077] FIG. 7 illustrates a composite image of samples tested in a
0.94 molar sulfuric acid bath, processed with a square wave voltage
and a DC rectifier. The samples 70V (green-yellow), 90V
(pink-rose), and 105V (blue-rose) exhibit color that varied
according to the processing conditions for the samples.
[0078] FIG. 8 presents x-ray diffraction data from the samples of
FIG. 7. The anatase peak for the samples is labeled--as shown in
the figure, each sample exhibits an anatase peak. FIG. 9 presents a
x-ray diffraction data for materials according to the present
disclosure (uppermost chart) that exhibit a purplish color that is
essentially equivalent to the color of vacuum sputter-coated
materials (lower charts) which do not contain anatase in the
colored oxide film. The sputter-coating may not in all cases
demonstrate antimicrobial properties after light activation, as
sputter-coated film does not contain an anatase peak.
[0079] The present disclosure also provides kits. The disclosed
kits suitably include first and a second devices, each of the
devices having at least one surface that is at least partially
surmounted by a film of titanium oxide, that is at least partially
anatase in phase and that confers a visually perceptible color on
the devices, the first and second devices differing in visually
perceptible color and in at least one other physical
characteristic.
[0080] As one example, a kit may include multiple implants
featuring different colors. For example, the largest implant in the
kit may feature a green color, and the smallest implant may feature
a gold color. The colors may also be used to distinguish between
implants that differ in some other physical characteristic. For
example, a kit may include a gold-colored implant adapted for use
as a humerus implant, and a rose-colored implant adapted for use as
a radius implant. The kits may also include color-coded anchors,
nails, or screws that match or approximate the color of the devices
with which they are intended to cooperate. Alternatively, fasteners
may be color-coded by size, e.g., fasteners of 5 mm diameter are
gold-colored, and fasteners of 10 mm diameter are rose-colored.
[0081] The kit may also, in some embodiments, include a source of
that is operable to emit light of a wavelength and intensity
sufficient to cause the titanium dioxide to exhibit a biocidal
effect upon irradiation with light from the light source. This
light source may be a lamp, a laser, or similar. One exemplary
light source is the TL 20W/05 UV lamp from Phillips Co., Holland,
operating at about 360 nanometers. The near ultraviolet (NUV)
wavelength occurs primarily between 300 nm to 400 nm and the
preferred activation wavelength is from about 350 nm to about 380
nm. Fluorescent black lights coated with specific phosphers on the
inside of the tube may also be used, such as but not limited to,
europium doped strontium flouroborate or europium doped strontium
borate (368 nm-371 nm emission peak) and lead-doped barium silicate
(350 nm-353 nm emission peak). Other ultraviolet wavelengths
outside of the preferred anatase activation range such as
ultraviolet A (UVA) at 315 nm-400 nm, ultraviolet B (UVB) at 280
nm-315 nm, and middle ultraviolet (MUV) at 200 nm-300 nm may be
used. Antimicrobial activation may, in some embodiments, be tuned
as a function of light exposure. Other UV arc lamps such as xenon,
deuterium, mercury-xenon, and metal-halide provide a continuous
emission spectra and are not effective anatase activation sources.
The kits may include a removable package that is suitably
essentially transparent to ultraviolet light. The first, second, or
both devices are suitably disposed within the removable package.
The package may be a bag, a box, and the like. The kit may be
disposed in a suitcase, box, or other container. As described
elsewhere herein, the devices may be exposed to illumination to
activate them before being sealed into a package or sealed into a
kit.
[0082] The user suitably illuminates the implant or other device
before implantation, although the devices may be illuminated after
installation. Illumination and activation may also be effected
after the device is fabricated, or even after the device is
packaged. In this way, the fabricator may package the devices in a
sterile package (e.g., a bag or box) and then illuminate the device
to render it antimicrobial while within the sterile package. In
this way, the device may remain sterile until the user removes the
package in preparation for device installation. The devices may,
alternatively, be illuminated first and then sterilized when in a
package or sterilized and then packaged.
[0083] Additional Disclosure
[0084] The following is illustrative examples that are exemplary
only and do not serve to limit the scope of the present disclosure.
The X-Ray diffraction data generated from some tests show that
anatase may form close to the oxide thickness associated with a
gold color. In some cases, higher levels, other than green-gray and
gray, of crystalline anatase and/or rutile is associated with the
oxide thickness associated with a green color. For this reason,
gold and green anodized samples were chosen as additional test
samples.
[0085] Samples were tilted to an angle of 60-70.degree. in order to
detect the surface morphologies using scanning electron microscopy
(SEM). Observation of the tilted oxide showed different areas of
surface roughness that cannot be distinguished when the samples are
flat. Electron backscattered diffraction (EBSD) was used on two
green anodized samples to determine if there was a crystalline
difference in the different areas observed and the presence and
distribution of the crystalline phases if present. In order to
establish baseline information, one half of a titanium sample was
pickled (nitric-hydrolfluoric solution for 30 seconds) and the
other half remained the natural forming surface oxide. SEM images
of the natural surface are shown in FIG. 10 and the pickled surface
in FIG. 11. FIG. 10 shows a roughened surface from the as rolled
titanium sheet, while FIG. 11 shows a less roughened surface and
etching of the grain boundaries.
[0086] FIGS. 12-14 show the surface oxide of a gold anodized
titanium sample tested in 0.5 M sulfuric acid. The low
magnification SEM image (FIG. 11) shows a distribution of light and
dark colored areas without any discernible surface roughness or
morphological differences. FIG. 12 shows a higher magnification
(1000.times.) of the same area. No surface difference can be
distinguished between the darker and lighter areas and is
comparable to the nitric-hydrofluoric pickled surface (FIG. 11).
FIG. 14 shows an even higher magnification (5000.times.) in which
the lighter surface area has some micro porosity forming while the
dark area appears to remain smooth. The X-Ray diffraction data did
not show any peak intensities for anatase or rutile, indicating
that the surface is amorphous or the crystalline areas present have
a small intensity that cannot be distinguished from the
background.
[0087] FIGS. 15-17 show the surface oxide of a gold anodized
titanium sample tested in 2 M sulfuric acid. FIG. 15 is a low
magnification SEM image that shows a distribution of light and dark
colored areas comparable to the 0.5 M gold sample (FIG. 12). FIG.
16 is a higher magnification (1000.times.) image that shows a few
titanium grains with little to no discernible surface morphology
difference between the dark and lighter areas. However, a higher
magnification (5000.times.) of the same area shown in FIG. 17 shows
the lighter area to have a more mirco porous surface morphology
compared to the smooth dark area. This morphology difference is
similar to that shown in FIG. 14 (high magnification 0.5 M gold
sample) but seems to cover more of the surface. Again, no anatase
or rutile peaks were found in the x-ray diffraction data for this
sample.
[0088] FIGS. 18-20 show the surface oxide of a green anodized
titanium sample tested in 0.94 M sulfuric acid. The low
magnification SEM image (FIG. 18) shows a distribution of light and
dark colored grains without any discernible surface roughness
differences. FIG. 19 shows a higher magnification (1000.times.) of
the same area. A surface roughness and morphology difference can be
clearly seen between the darker smooth areas in the middle of the
image compared to the lighter areas around the periphery. FIG. 20
shows an even higher magnification (5000.times.) in which the
texture differences can be distinguished as boundaries between
smooth flat areas and porous rougher areas. EBSD was used to
evaluate the boundary seen in FIG. 20 at an approximate
magnification of 15,000.times.. The high magnification was needed
to distinguish the very small anatase and rutile grains.
[0089] EBSD data is given in FIGS. 21-23. FIG. 21 shows the SEM
representation of the area being scanned. FIG. 22 is a grain
orientation map which shows the division of the amorphous and
crystalline regions of the area scanned shown in FIG. 21. Comparing
FIGS. 21 and 22, the boundary between the smooth area and porous
area can be distinguished as the boundary between the crystalline
phase and amorphous phase. Furthermore, the different grain
orientations found in the anatase and rutile crystalline area shows
that the crystalline oxide is formed by many small different
crystals formed on a single titanium grain. FIG. 23 shows the
distribution of the crystalline phases. Anatase was found to be the
more prominent crystalline phase, as was to be expected from the
XRD data (FIG. 24). It should be understood that with EBSD testing
the absence of the detection of a crystalline phase does not
necessarily mean that the area is amorphous. Accordingly, the
porous texture seen in FIGS. 20 and 21 is, without being bound to
any particular theory, likely a highly crystalline area of anatase
and rutile.
[0090] FIGS. 25-27 show the surface oxide of a green anodized
titanium sample tested in 2.0 M sulfuric acid. The low
magnification SEM image (FIG. 25) shows a distribution of light and
dark colored grains without any discernible surface texture
differences similar to the 0.94 M green sample shown in FIG. 21.
FIG. 26 shows a higher magnification (1000.times.) of the same
area. The texture difference seen in the 0.94 M green sample cannot
be as clearly seen in FIG. 26. A higher magnification (5000.times.)
image in FIG. 27 shows that the boundaries that were evident in
FIG. 20 (0.94 M) are not as apparent in the 2.0 M sample. Further
inspection shows that the textured areas still have micro porosity
that is not found on the smooth areas. EBSD was used to evaluate a
representative area at an approximate magnification of
15,000.times..
[0091] EBSD data is given in FIGS. 28-30. FIG. 28 shows the SEM
representation of the area being scanned. FIG. 29 shows the
amorphous and crystalline regions of the area scanned. Comparing
FIGS. 28 and 29, there is no distinguishable boundary between the
amorphous and crystalline areas of the surface oxide. The different
grain orientations found in the crystalline area may show that the
crystalline oxide is formed by many small different textured
crystals. FIG. 30 shows the distribution of the crystalline phases.
Anatase was found to be the more prominent crystalline phase
compared to rutile.
[0092] Comparing the SEM images for the gold anodized samples, the
higher magnification images show a higher degree of the micro
porosity surfaces for the 2 M compared to the 0.5 M sample. Without
being bound to any particular theory, these areas may be the
beginning of a crystalline oxide area being formed. The SEM and
EBSD data from the 0.94 M and 2.0 M green samples shows a
preliminary trend that as the molarity increases the confluence of
the crystalline phase also increases. Comparing the X-Ray
diffraction scans for both samples (FIGS. 24 and 31) indicates that
the anatase peak heights for both samples are very similar. Without
being bound to any particular theory, this may be an indicator that
the crystalline phases (anatase and rutile) levels are similar for
each thickness (color) but the confluence of the oxide may be
influenced by the molarity of the anodization bath.
* * * * *