U.S. patent application number 16/327210 was filed with the patent office on 2019-06-27 for colored vitreous enamel composition for electrosurgical tool.
The applicant listed for this patent is Medtronic Advanced Energy LLC. Invention is credited to Xiaoming CHENG, Zahedul HUQ, William X. SIOPES, JR..
Application Number | 20190192213 16/327210 |
Document ID | / |
Family ID | 60570229 |
Filed Date | 2019-06-27 |
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United States Patent
Application |
20190192213 |
Kind Code |
A1 |
CHENG; Xiaoming ; et
al. |
June 27, 2019 |
COLORED VITREOUS ENAMEL COMPOSITION FOR ELECTROSURGICAL TOOL
Abstract
A colored (viz., not black) vitreous enamel coating for an
electrosurgical metal cutting blade provides heat-resistant,
durable blade coloration and facilitates differentiation or
discrimination between, or identification of, different blades.
Different colors may be employed on different blade shapes in an
array of blades, on blades used for different surgical procedures,
or on blades used on different tissue types. The color may be
applied to a portion of a blade to denote an edge or other feature.
The color may preferentially absorb the primarily blue-trued light
emitted by an electrosurgery plasma and preferentially reflect
light of other hues; make the blade more visible against
surrounding tissues; or discourage reflection of visible or other
light (e.g., infrared radiation) in colors that might interfere
with markers, sensors or other instruments designed to measure
light emitted by or passing through nearby tissue such as by
transillumination.
Inventors: |
CHENG; Xiaoming; (Keller,
TX) ; SIOPES, JR.; William X.; (Tyngsborough, MA)
; HUQ; Zahedul; (Keller, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Medtronic Advanced Energy LLC |
Minneapolis |
MN |
US |
|
|
Family ID: |
60570229 |
Appl. No.: |
16/327210 |
Filed: |
November 14, 2017 |
PCT Filed: |
November 14, 2017 |
PCT NO: |
PCT/US2017/061623 |
371 Date: |
February 21, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62421895 |
Nov 14, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C03C 10/0036 20130101;
A61B 2018/00607 20130101; A61B 18/14 20130101; A61B 18/148
20130101; A61B 2018/00107 20130101; A61B 2018/00083 20130101; C03C
3/066 20130101; C03C 8/04 20130101; C03C 2204/00 20130101; C03C
10/0054 20130101; A61B 2018/126 20130101; C03C 10/00 20130101; C03C
3/093 20130101; A61B 18/1206 20130101; A61L 31/14 20130101; C03C
4/16 20130101; A61B 18/1402 20130101; C03C 8/02 20130101; C03C 8/14
20130101; A61B 2018/1253 20130101; A61B 2018/1412 20130101; A61L
31/026 20130101; A61B 2018/00125 20130101; A61B 2018/00148
20130101; A61B 2018/1415 20130101; C03C 3/064 20130101; C03C 4/02
20130101; A61B 2018/00601 20130101; C03C 3/091 20130101; C03C 8/16
20130101 |
International
Class: |
A61B 18/14 20060101
A61B018/14; A61B 18/12 20060101 A61B018/12; C03C 3/066 20060101
C03C003/066; C03C 3/091 20060101 C03C003/091; C03C 8/14 20060101
C03C008/14 |
Claims
1. An article comprising: (a) an electrosurgical cutting blade
comprising a metal electrode, and (b) a colored vitreous enamel
coating on at least a portion of the metal electrode.
2. (canceled)
3. (canceled)
4. (canceled)
5. (canceled)
6. (canceled)
7. (canceled)
8. The article according to of claim 1, wherein the vitreous enamel
coating has a white coloration.
9. The article of claim 1, wherein the vitreous enamel coating has
a red, green or blue coloration.
10. The article of claim 1, wherein the vitreous enamel coating has
a color that preferentially absorbs light emitted by an
electrosurgery plasma and preferentially reflects light of other
hues.
11. The article of claim 1, wherein the vitreous enamel coating has
a color that enhances visibility of the blade against nearby
tissue.
12. The article of claim 1, wherein the vitreous enamel coating has
a color that discourages reflection of visible or other light in
colors that might interfere with markers, sensors or other
instruments that measure light emitted by or passing through nearby
tissue.
13. The article of claim 1, wherein the colored vitreous enamel is
an amorphous glass composition.
14. The article of claim 1, wherein the colored vitreous enamel is
a glass-ceramic composition having a crystalline phase.
15. The article of claim 1, wherein the colored vitreous enamel
comprises an aluminoborosilicate glass.
16. The article of claim 1, wherein the colored vitreous enamel
coating contains a refractory inorganic pigment that imparts such
color to the coating.
17. The article of claim 1, wherein the colored vitreous enamel
coating contains a non-infrared-absorptive colored inorganic
pigment.
18. The article of claim 1, wherein the colored vitreous enamel
coating is made from a glass frit that contains a colorant that
becomes part of the glass and imparts such color to the
coating.
19. The article of claim 1, wherein the colored vitreous enamel
coating contains a crystalline phase that imparts such color to the
coating.
20. The article of claim 1, wherein the colored vitreous enamel
coating contains at least 20 volume percent of a crystalline
phase.
21. (canceled)
22. An article according to claim 1, coating according to claim 2
or method according to claim 3 or claim 4, The article according to
of claim 1, wherein the colored vitreous enamel coating contains
sufficient colored pigment or colorant, or has sufficient
crystallinity, so that the metal electrode is not visible through
the coating under typical indoor illumination.
23. The article of claim 1, wherein the colored vitreous enamel
coating contains sufficient colored pigment or colorant, or has
sufficient crystallinity, so that a specular second surface
reflection from the metal electrode is not visible through the
coating during plasma operation.
24. The article according to claim 1, wherein the vitreous enamel
is formed from a glass frit comprising, as molar percentages:
TABLE-US-00002 SiO.sub.2 30-50%, B.sub.2O.sub.3 0.5-15%,
Al.sub.2O.sub.3 0.5-10%, SrO 5-30%, CaO 5-30%, and ZnO 0.5-20%.
25. The article according to claim 1, wherein the vitreous enamel
is formed from a glass frit comprising SiO.sub.2, B.sub.2O.sub.3,
Al.sub.2O.sub.3, and optionally one or more of SrO, BaO, CaO, MgO,
ZnO, Na.sub.2O, K.sub.2O or a combination thereof.
26. (canceled)
27. The article according to claim 1, wherein the metal electrode
is titanium, tantalum, molybdenum, tungsten, stainless steel, or an
alloy thereof.
28. The article of claim 1, further comprising an insulated handle
attached to the electrosurgical cutting blade and housing at least
one conductor that can connect the metal electrode to a
radiofrequency energy power supply.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 62/421,895 filed Nov. 14, 2016 and entitled
"ENAMEL COMPOSITION FOR ELECTROSURGICAL TOOL", the disclosure of
which is incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] This invention relates to vitreous enamel compositions for
coating electrosurgical cutting blades, and to the coated blades
and methods for their manufacture and use.
BACKGROUND
[0003] Certain electrosurgical cutting equipment utilizes plasma
energy to dissect tissue and coagulate blood vessels while
producing minimal collateral damage to surrounding tissue. The
cutting blade designed for the electrosurgical application often
employs an insulating layer on a portion of the cutting blade to
prevent energy from dispersing onto the bulk surface of the blade.
Additionally, the insulating layer typically defines an uninsulated
cutting edge (viz., an exposed electrode). The cutting edge, upon
the introduction of a certain pattern of radiofrequency (RF)
waveform, creates a substantially uniform and focused electrical
field that upon contact with the cells in tissue forms a
plasma-mediated discharge.
[0004] Despite improvements, there remains a need for even better
vitreous enamel coatings for electrosurgical cutting blades. Such
vitreous enamel coatings are disclosed and claimed herein.
SUMMARY
[0005] Conventional electrosurgical devices are available with
blades having a variety of shapes and configurations to facilitate
their use on particular tissues or in particular surgical
procedures. The blades themselves can be rather small, and careful
inspection may be needed to distinguish between them.
[0006] Some electrosurgical blades include an organic coating layer
(e.g., of polytetrafluoroethylene (PTFE), polyurethane or silicone
resin) disposed over the blade substrate, For example,
electrosurgical blades available from Megadyne traditionally employ
a green-tinted opaque PTFE coating, with the same shade of green
being employed on all blades. The green coating has been made the
subject a Trademark Registration No. 2021699. A uniform color may
be used to identify the blade supplier, but does not differentiate
between different blade shapes. Also, an organic coating may burn
off during use, and may produce odors, smoke or volatile products
of degradation or combustion that may be objectionable to a
surgeon, other operator or other personnel in the operating
theater.
[0007] Electrosurgical blades available from Medtronic
traditionally employ a translucent black vitreous enamel coating,
with a typical coating thickness of about 100 .mu.m. Based on an
understanding that black does not represent a color, these blades
do not have a colored vitreous enamel coating. Typically, the
degree of translucency is such that the underlying metal substrate,
including grinding or polishing marks, can be seen through the
coating. During use, light emitted by the plasma discharge may pass
through the coating, strike the polished metal substrate, and be
specularly reflected back through the coating. Depending on a
nearby individual's angle of view, a specular second surface
reflection from the underlying substrate may represent an
objectionable source of glare.
[0008] Light penetrating a translucent vitreous enamel coating may
also heat up the underlying metal substrate. Although some heating
is inevitably part of the plasma discharge process, and although
temperatures may reach as high as 800.degree. C. at the cutting
edge, it nonetheless is desirable to avoid excessive heating in
order to prolong blade life and reduce deterioration of the
vitreous enamel or other insulative coating.
[0009] Vitreous enamel coatings may be formed from a glass fit that
is melted atop a metal substrate and optionally heat processed to
alter the physical properties, crystallinity or other
characteristics of the resulting vitreous enamel. In some
embodiments, the coating is delivered onto the metal substrate
through a slurry which is formed by combining glass frit powders,
binder, and solvent. The binder and solvent can be initially burned
off in a burn-out process and the coating subsequently fired at
elevated temperatures to form the vitreous enamel insulating layer
on the metal substrate.
[0010] Although color has not traditionally been deliberately
imparted to vitreous enamel coatings for electrosurgical blades,
coloration (e.g., prominent coloration) may be imparted to such
coatings by employing additives or steps that result in selective
absorption or scattering of specific visible wavelengths. The
components of the glass fit and processing conditions are desirably
selected to achieve a desired color and opacity.
[0011] The present invention thus provides in one aspect an article
comprising: [0012] (a) an electrosurgical cutting blade comprising
a metal electrode, and [0013] (b) a colored vitreous enamel coating
on at least a portion of the metal electrode.
[0014] The invention provides in another aspect a vitreous enamel
coating comprising a colored glass formed from glass frit, wherein
the coating is disposed on a metal electrode for an electrosurgical
cutting blade.
[0015] The invention provides in yet another aspect a method
comprising providing a colored vitreous enamel precursor, applying
the vitreous enamel precursor onto at least a portion of a metal
electrode suitable for use as an electrosurgical cutting blade, and
firing the vitreous enamel precursor to form a colored vitreous
enamel coating. In an embodiment, different vitreous enamel colors
are employed on different blade types or blade shapes in an array
of blades, or on blades used for different surgical procedures or
on different tissue types, in order to facilitate easier
discrimination between blades, procedures or tissues. In another
embodiment, the same color is used on all blades in an array of
blades from a particular manufacturer, and the color serves as a
heat-resistant durable source identifier for products from that
manufacturer.
[0016] The electrosurgical cutting blade with its colored vitreous
enamel insulating layer may be connected to a power source on an
electrosurgical generator. The invention thus provides in another
aspect a method comprising intermittently supplying radiofrequency
energy to an electrosurgical cutting blade having a colored
vitreous enamel coating to create a plasma-mediated discharge.
[0017] In some embodiments of the above-described article, coating
and methods, the vitreous enamel coating contains sufficient
colored pigment or colorant, or has sufficient crystallinity, so
that the underlying metal electrode is not visible through the
coating under typical indoor illumination. In additional
embodiments, the vitreous enamel coating contains sufficient
colored pigment or colorant, or has sufficient crystallinity, so
that a specular second surface reflection from the underlying metal
electrode is not visible through the coating during plasma
operation.
[0018] In some embodiments of the above-described article, coating
and methods, the vitreous enamel coating includes a
non-infrared-absorptive (e.g., infrared-reflective) colored
inorganic pigment. Such pigments may reduce or discourage
undesirable heating caused by absorption of infrared energy emitted
by the plasma.
[0019] In some embodiments of the above-described article, coating
and methods, the chosen color may be a color other than white.
White coatings tend to have good infrared rejection, especially if
made using titanium dioxide, but may also exhibit objectionable
glare. In some embodiments the coating is a primary color (such as
a red, green or blue color in an additive RGB color space). In some
embodiments, the coating has a color other than white. In some
embodiments, the coating has a color (e.g., yellow or orange) that
preferentially absorbs the primarily blue-hued light emitted by the
plasma and preferentially reflects light of other hues. In some
embodiments, the coating has a color (e.g., lime green, or
fluorescent yellow) that enhances visibility of the blade against
nearby tissue, In some embodiments, the coating has a color that
discourages reflection of visible or other light (e.g., infrared
radiation) in colors that might interfere with Markers, sensors or
other instruments designed to measure light emitted by or passing
through nearby tissue, e.g., by transillumination.
[0020] The above summary of the present invention is not intended
to describe each disclosed embodiment or every implementation of
the present invention. The description that follows more
particularly exemplifies illustrative embodiments. In several
places throughout the application, guidance is provided through
lists of examples, which can be used in various combinations. In
each instance, the recited list serves only as a representative
group and should not be interpreted as an exclusive list.
[0021] The details of one or more embodiments of the invention are
set forth in the description below. Other features, objects, and
advantages of the invention will be apparent from the description,
drawing, and from the claims.
BRIEF DESCRIPTION OF THE DRAWING
[0022] In the accompanying Drawing, FIG. 1 is a perspective view of
an electrosurgical cutting tool;
[0023] FIG. 2 is an orthogonal side view of a vitreous
enamel-coated electrosurgical cutting blade;
[0024] FIG. 3 is a cross-sectional schematic view of an edge
portion of an electrosurgical cutting blade with a pigmented
colored vitreous enamel coating;
[0025] FIG. 4 is a cross-sectional schematic view of an edge
portion of an electrosurgical cutting blade with an opaque colored
vitreous enamel coating;
[0026] FIG. 5 is a cross-sectional schematic view of a portion of a
coated electrosurgical cutting blade illustrating specular and
diffuse reflection;
[0027] FIG. 6 is a schematic of one embodiment of a process for
forming a vitreous enamel coating on an electrosurgical cutting
blade; and
[0028] FIG. 7 is a scanning electron microscope (SEM) image showing
the crystalline structure of the vitreous enamel coating prepared
in Example 5.
[0029] Like reference symbols in the various figures of the Drawing
indicate like elements. The elements in FIG. 1 and FIG. 3 through
FIG. 5 are not to scale.
Selected Definitions
[0030] Unless otherwise specified, the following terms as used
herein have the meanings provided below.
[0031] As used herein, "a," "an," "the," "at least one," and "one
or more" are used interchangeably. Thus, for example, a coating
composition that comprises "a" pigment can be interpreted to mean
that the coating composition includes "one or more" pigments.
[0032] The term "amorphous" means a solid composition that lacks
the order present in crystalline structures.
[0033] The terms "coefficient of thermal expansion" or "CTE"
describes a thermomechanical property of a material and its ability
to expand in size as the temperature is raised. For purposes of
this disclosure, the CTE value is measured in accordance with ASTM
E228-17, Standard Test Method for Linear Thermal Expansion of Solid
Materials with a Push-Rod Dilatometer. The test heating rate is
5.degree. C./min and the temperature range is from room temperature
to about 1000.degree. C. Those of ordinary skill in the art will
recognize that the vitreous enamel is not tested after it is coated
onto the metal electrode but rather the fired glass frit comprising
the vitreous enamel is tested and corresponds to the CTE value of
the vitreous enamel after coating and firing.
[0034] The terms "color" and "colored" mean having a hue (e.g., a
primary color such red green or blue in an RGB additive color
system, or a hue made by mixing two or more such primary colors) or
a white coloration, but does not include a black coloration.
[0035] The term "crystalline" refers to a solid material that
possesses a highly ordered or arranged structure, may in some
circumstances form a crystal lattice, and may in some circumstances
be opaque.
[0036] The terms "electrosurgical cutting tool" or "electrosurgical
cutting blade" generally refer to the electrosurgical equipment use
of plasma energy to dissect tissue or coagulate blood vessels while
producing minimal collateral damage to surrounding tissue.
[0037] The terms "enamel" or "vitreous enamel" describe a
transparent, semitransparent or opaque glassy substance applied to
metallic or other hard surfaces, and capable of serving as a
dielectric or insulating layer for an electrosurgical cutting
blade.
[0038] The term "glass-ceramic" refers to a vitreous enamel
composition that includes both an amorphous phase and a crystalline
phase.
[0039] The term "glass frit" means the basic materials, often in
particulate form, that may be wholly fused, for making glass or
vitreous enamel.
[0040] The term "metal substrate" refers the metal electrode of an
electrosurgical cutting tool that forms the cutting blade and
provides a base upon which the vitreous enamel is applied.
[0041] The term "opaque" refers to a glass that reflects rather
than refracts light in a wavelength range of interest (typically
but not in all cases the visible light range from 400 to 700
nm).
[0042] The terms "preferred" and "preferably" refer to embodiments
of the invention that may afford certain benefits, under certain
circumstances. However, other embodiments may also be preferred,
under the same or other circumstances. Furthermore, the recitation
of one or more preferred embodiments does not imply that other
embodiments are not useful, and is not intended to exclude other
embodiments from the scope of the invention.
[0043] The recitation of numerical ranges by endpoints includes all
numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5,
2, 2.75, 3, 3.80, 4, 5, etc.). Furthermore, disclosure of a range
includes disclosure of all subranges included within the broader
range (e.g., 1 to 5 discloses 1 to 4, 1.5 to 4.5, 1 to 2,
etc.).
DETAILED DESCRIPTION
[0044] As mentioned above, color has not traditionally been
deliberately imparted to vitreous enamel coatings for
electrosurgical blades. Color may however be imparted to such
coatings by employing additives or steps that result in selective
absorption or scattering of specific visible wavelengths. For
example, inorganic light-absorbing or light-reflecting pigment
particles having one or more colors may be dispersed into a glass.
This may be done in a variety of ways, including adding the pigment
particles to a glass frit from which a vitreous enamel will be
prepared. In another embodiment, the pigment particles may be added
to a slurry containing separately prepared milled glass particles
together with a binder and optional solvent, followed by subjecting
the slurry to a binder burnout step to remove the binder and
optional solvent, followed by a firing step to form the vitreous
enamel. The pigment particles desirably are more refractory than
the glass so that they do not react with the glass during firing.
The pigment particles may be used to impart color to a translucent
or opalescent vitreous enamel. At a sufficiently high loading
level, the pigment particles may provide an opaque vitreous
enamel.
[0045] Color may also be imparted to a vitreous enamel by adding to
the glass frit one or more colorants (e.g., certain metal oxides)
that become a part of the glass and cause absorption of energy in a
wavelength range of interest (e.g., the visible light range).
Without intending to be bound by theory, such absorption may
facilitate transition of electrons from an unfilled d or f orbital
of lower energy to one of higher energy upon exposure of the
vitreous enamel to energy in the desired wavelength range.
[0046] Color may also be imparted to a vitreous enamel by selecting
suitable frit ingredients or suitably processing the molten enamel
so as to form a visibly distinct crystalline phase that desired
wavelengths of light, resulting in a colored appearance, or
scatters all wavelengths of visible light, resulting in a white or
off-white colored appearance.
[0047] If desired, the various approaches outlined above may be
combined. For example, a variety of inorganic pigment particles and
colorants may be combined with one another or with crystallization
to obtain additional colors, and if desired increased opacity.
[0048] FIG. 1 depicts an embodiment of an electrosurgical cutting
device 10. Device 10 includes an insulated handle 12 with hand
(e.g., finger) grip ridges 13 as shown on the lower part thereof.
This portion is intended to be held in the surgeon's hand (not
shown in FIG. 1). Two control buttons 14, 16 activate electric
switches (not shown in FIG. 1) which are provided for respectively
selecting cutting or coagulation regimes. The rear portion 18 is
for balance and for housing at least one cable 19 that may
terminate in a conventional electrical connector (not shown in FIG.
1) for connection to a lead, leads or mating connector of a
radiofrequency energy power supply (not shown in FIG. 1). The
dimensions of the device of FIG. 1 are such that it is comfortably
held in a hand, yet small enough for surgery for the intended
application. The working end of the device of FIG. 1 includes at
its distal end an electrosurgical cutting blade 20. Electrosurgical
cutting blade 20 includes a metal substrate or electrode 21 housed
in an intermediate portion or shaft 22. Intermediate portion 22
provides an insulated support that holds and extends the distal end
of electrosurgical cutting blade 20 at an appropriate surgical
viewing and cutting or coagulating distance from the surgeon's
hand. The exposed distal portion of electrosurgical cutting blade
20 includes a colored vitreous enamel insulative coating 24. A
non-limiting embodiment of an exemplary electrosurgical device is
disclosed in U.S. Pat. No. 8,414,572 B2, herein incorporated by
reference in its entirety.
[0049] As depicted in FIG. 1, device 10 has a single, flattened
blade 20 fixedly mounted in intermediate portion 22. As will be
appreciated by persons having ordinary skill in the art, the
disclosed electrosurgical device may have a variety of other blade
shapes and blade configurations, including blades with square
edged, slant-edged, cylindrical, needle-like, bent, bendable or
telescoping features. The disclosed electrosurgical device may be a
monopolar device such as is shown in FIG. 1, or a bipolar device
with two or more electrodes as may be used in some forms of
electrosurgery.
[0050] In operation, the steps involved for cutting or otherwise
operating on (e.g., coagulating) tissue with an electrosurgical
device such as device 10 of FIG. 1 generally include contacting the
tissue with a plasma generating electrode and applying an electric
signal, having in some cases a low duty-cycle RF waveform, to the
electrode. The signal causes the formation of a plasma discharge
along the electrode between the electrode edge and the tissue and
this plasma performs the tissue cutting or other operation.
[0051] The actual nature of the applied electrical signals which
are suitable to create the desired plasma effect is well known in
the field. For instance, in one embodiment the applied signal is an
RF signal having a frequency in the range of 100 KHz to 10 MHz.
Typically this energy is applied in the form of bursts of pulses.
Each burst typically has a duration in the range of 10 microseconds
to 1 millisecond. The individual pulses in each burst typically
each have a duration of 0.1 to 10 microseconds with an interval
therebetween of 0.1 to 10 microseconds. The actual pulses are
typically square waves and bi-phasic, that is alternating positive
and negative amplitudes. Generally the interval between pulses must
be shorter than a lifetime of the plasma vapor cavity in order to
maintain the cavity and the plasma regime during each pulse burst.
In one embodiment the bursts are separated by a duration of at
least one millisecond.
[0052] The energy is delivered to the functional edge of the device
through an electrosurgical cutting blade. FIG. 2 is an orthogonal
side view of one embodiment of an electrosurgical cutting blade 20.
The electrosurgical cutting blade 20 includes a metal electrode or
substrate 22 at least a portion of which is coated with a colored,
opaque vitreous enamel coating 24. An exposed edge 26 of the metal
substrate 22, upon the introduction of radiofrequency energy, is
capable of creating a substantially uniform and enhanced electrical
field that upon contact with the cells in tissue forms the plasma
medium. The vitreous enamel coating 24 functions as a
non-conductive surface and thereby limits the formation of the
plasma medium to the defined edge 26.
[0053] The chosen vitreous enamel coating coloration can serve one
or more of a variety of functions, including identifying the blade
manufacturer, making it easier for surgeons or other personnel to
distinguish between different blades in an array of blades,
identifying blades for use with particular surgical procedures or
for use on particular tissues, making the blade more visible
against nearby tissue or nearby fluids, absorbing light emitted by
a nearby plasma-mediated discharge, reducing second surface
reflections from an underlying metal electrode substrate, reducing
glare caused by specular reflection from the plasma. mediated
discharge or lights in the operating field, and discouraging
reflection of visible or other light (e.g., infrared radiation) in
colors that might interfere with markers, sensors or other
instruments designed to measure light emitted by or passing through
nearby tissue, e.g., by transillumination.
[0054] FIG. 3 is a cross-sectional schematic view of an edge
portion of a vitreous enamel-coated electrosurgical cutting blade
30. Blade 30 includes metal electrode substrate 32, colored
vitreous enamel coating 34 containing refractory inorganic oxide
pigment particles 35, and edge 36. Coating 34 may be amorphous or
crystalline, but contains sufficient particles 35 so that coating
34 has a perceptible coloration.
[0055] Due to surface tension and other factors during application
or firing of the frit from which coating 34 is made, coating 34
typically will have a reduced thickness near edge 36. In some
embodiments, edge 36 may be exposed following firing. If desired, a
mechanical impact, abrasive, electrical energy, acid etching or
other measures may be used to remove a portion of, or to discourage
the formation of, coating 34 proximate edge 36, thereby resulting
in a region with reduced thickness or no coating at all proximate
edge 36. Such reduced thickness or exposed edge provides a
localized reduction in the breakdown voltage strength of coating 36
and helps promotes initial plasma formation and plasma maintenance
proximate edge 36 when electromagnetic energy is applied to metal
electrode 32.
[0056] In a preferred embodiment, coating 34 has a distinctive,
easily perceptible coloration and a non-transparent (e.g., opaquely
pigmented) appearance. In a further preferred embodiment, coating
34 contains sufficient pigment particles 35 so that substrate 32 is
not visible through portions of coating 34 that are remote from
edge 36 (viz., portions that are not adjacent to edge 36 and
consequently do not have a reduced thickness) under normal indoor
illumination. In another further preferred embodiment, coating 34
contains sufficient pigment particles 35 so that substrate 32 is
not visible through such remote portions of coating 34 under the
illumination provided by the plasma mediated discharge or under
typical operating theater illumination. The pigment particles 35 in
coating 34 consequently preferably reduce or eliminate unwanted
second surface specular reflection of light traveling through
(viz., into and out of) coating 34. Such light is instead
preferentially absorbed or scattered (e.g., via diffuse reflection)
by the pigment particles 35.
[0057] Coloration like that discussed above in connection with FIG.
3 may also be provided by adding to the glass frit one or more
colorants (e.g., certain metal oxides) that become a part of the
glass and cause absorption of energy in a wavelength range of
interest (e.g., the visible light range). Such additives may be
used in place of or in addition to the inorganic pigment particles
35, and when used by themselves may provide colors and a color
gamut different from that available through the use of the
inorganic pigment particles by themselves.
[0058] FIG. 4 is a cross-sectional schematic view of an edge
portion of a vitreous enamel-coated electrosurgical cutting blade
40. Blade 40 includes metal electrode substrate 42, colored
vitreous enamel coating 44, and edge 46. Blade 40 is similar to
blade 30 in FIG. 3, and its coating 44 may contain pigment
particles (not shown in FIG. 4, but like particles 35 if present),
but coating 44 also contains sufficient crystallinity so that
coating 44 has a perceptible coloration (e.g., a white or off-white
coloration). In a preferred embodiment, coating 44 has a
distinctive, easily perceptible coloration and a non-transparent
(e.g., opaque) appearance. In a further preferred embodiment,
coating 44 contains sufficient crystallinity so that substrate 42
is not visible through portions of coating 44 that are remote from
edge 46 under normal indoor illumination. In another further
preferred embodiment, coating 44 contains sufficient crystallinity
so that substrate 42 is not visible through such remote portions of
coating 44 under the illumination provided by the plasma mediated
discharge or under typical operating theater illumination. The
crystallinity in coating 44 consequently preferably reduces or
eliminates unwanted second surface specular reflection of light
traveling through (viz., into and out of) coating 44. Such light is
instead preferentially absorbed or scattered (e.g., via diffuse
reflection) by the presence of a crystalline phase or phases within
coating 44.
[0059] FIG. 5 is a cross-sectional schematic view of three portions
of a coated electrosurgical cutting blade 50. Blade 50 is shown on
the left of FIG. 5 with an uncoated metal substrate portion 52a
having exposed upper and lower metal surfaces 51a and 53a,
respectively; in the center of FIG. 5 with a coated metal substrate
portion 52b having on its lower surface 51b and upper surface 53b
an unfilled transparent or translucent layer of vitreous enamel
coating 54b; and on the right of FIG. 5 with metal substrate
portion 52c having on its lower surface 51c and upper surface 53c
an opaque layer of vitreous enamel coating 54c filled with
refractory inorganic particles 55 that impart color to layer 54c
and scatter light. Different coatings are shown on substrate
portions 52b and 52c. In a typical vitreous enamel coated
electrosurgical blade, there may be an uncoated distal section like
portion 52a, and a proximal portion bearing a vitreous enamel
coating. Often the coating will be the same throughout, but this is
not required. Different coatings, different-colored coatings, or a
combination of colored and uncolored (e.g., black or transparent)
coatings may be used on different portions of the blade. For
example, in an asymmetric blade having a single sharpened edge, a
distinctive colored or uncolored coating may be applied to regions
remote from the edge, and a different distinctive colored or
uncolored coating may be applied to a region encompassing the edge,
so as to assist the surgeon in readily identifying the edge
location.
[0060] Incident light ray I.sub.1 is shown striking the upper
surface 53a of substrate portion 52a at a 60.degree. angle with
respect to perpendicular (normal) dashed line N.sub.1, and
undergoing specular reflection as reflected ray R.sub.1 travelling
away from upper surface 53a at a similar 60.degree. angle. Because
the surface of an electrosurgical cutting blade is typically ground
flat and may be highly polished, the reflected ray R.sub.1 will
typically be nearly as intense and nearly as focused as incident
ray I.sub.1.
[0061] Incident light ray I.sub.2 is shown striking the upper
surface of vitreous enamel coating 54b on substrate portion 52b at
a 60.degree. angle, undergoing refraction through coating 54b,
striking and being specularly reflected away from upper surface
53b, passing back through coating 54b and emerging at a 60.degree.
angle from the upper surface of coating 54b as specular reflected
light ray R.sub.2. As was the case for rays I.sub.1 and R.sub.1,
reflected ray R.sub.2 may be nearly as intense and nearly as
focused as incident ray I.sub.2.
[0062] Incident light ray I.sub.3 is shown striking the upper
surface of vitreous enamel coating 54c on substrate portion 52c at
a 60.degree. angle. Due to the presence of refractory inorganic
pigment particles 55 in coating 54c, incident ray I.sub.3 is
diffusely reflected away from coating 54c as reflected rays
R.sub.n. Reflected rays R.sub.n will present a less intense,
unfocused appearance and exhibit much less glare than reflected
rays R.sub.2 and R.sub.3.
[0063] The disclosed electrosurgical cutting blade includes a metal
electrode that provides electrical connectivity to the power source
and offers (or may be altered to offer) an exposed edge to enable
the formation of plasma. Non-limiting examples of metals suitable
to form electrodes include titanium, tantalum, molybdenum,
tungsten, stainless steel, or alloys thereof. In some embodiments,
the metal electrode can be cut or stamped from metal substrates.
Secondary process steps such as etching, grinding or polishing may
also be used on blades intended for use in certain surgical
applications. The dimensions and shape of the metal electrode may
also vary to accommodate different surgical applications. The metal
electrode in some preferred embodiments possesses a CTE value from
about 6, 8 or 10.times.10.sup.-6/.degree. C. up to about 11, 12, or
16.times.10.sup.-6/.degree. C.
[0064] The vitreous enamel may comprise a variety of glass or
glass-ceramic materials. The selection of suitable glass or
glass-ceramic materials will depend on several factors including,
but not limited to, the end use surgical application, nearby
illumination, blade design, expected temperatures during plasma
formation, power voltage of the RF generator, water content of the
tissue, and nature and extent of bonding to the metal substrate. In
certain aspects, the glass or glass-ceramic composition may be
selected to achieve a softening temperature that is near or
preferably above the temperatures realized during plasma formation.
For example, the softening temperature of a glass or glass-ceramic
composition may be at least 500.degree. C., at least 600.degree. C.
or at least 700.degree. C. A softening temperature of at least
500.degree. C. may in some circumstances enhance the durability of
the glass. By increasing the softening temperature, the glass may
withstand higher temperatures without softening and flowing during
use.
[0065] The vitreous enamel may be created through the combination
of various compounds to form certain types of glass. One embodiment
includes the formation of an aluminoborosilicate glass with at
least SiO.sub.2, B.sub.2O.sub.3 and Al.sub.2O.sub.3 compounds. In a
preferred aluminoborosilicate glass embodiment, the glass frit
includes one or more alkaline earth oxides. Preferred such alkaline
earth oxides include magnesium oxide (MgO), calcium oxide (CaO),
strontium oxide (SrO) and barium oxide (BaO). Higher molecular
weight alkaline earth oxides tend to provide higher CTE values. SrO
is an especially preferred alkaline earth oxide for use in the
disclosed alumninoborosilicate glasses.
[0066] As mentioned above, color can be imparted to the vitreous
enamel in a variety of ways. For example, a variety of refractive
inorganic pigments may be added to the disclosed vitreous enamel to
provide coloration, light scattering, and in preferred embodiments
an opaque coating. Exemplary such pigments include materials that
may be classified as ceramic or refractory pigments, and which may
contain elements such as cobalt (Co), chromium (Cr), copper (Cu),
iron (Fe) and manganese (Mn). Exemplary commercially available
pigments include BAYFERROX.TM., BAYOXIDE.TM., COLORTHERM.TM. and
LANXESS.TM. pigments from BASF, titanium dioxide pigments from
DowDuPont, chromic oxide pigments from Elementis, phosphate
ceramics from the ICL Group, and mineral-based pigments from Prince
Minerals GmbH. The chosen pigment should be biocompatible, and
consequently should avoid the use of potentially toxic metals
(e.g., lead, cadmium and other materials that will be familiar to
persons having ordinary skill in the art) and their oxides. In a
preferred embodiment, the pigment is a non-infrared absorptive
pigment. Exemplary such pigments include single or mixed metal
oxides formed from a variety of metals, e.g., from aluminum,
antimony, bismuth, boron, chromium, cobalt, gallium, indium, iron,
lanthanum, lithium, magnesium, manganese, molybdenum, neodymium,
nickel, niobium, silicon, tin, titanium, vanadium or zinc.
Exemplary metal oxides include Cr.sub.2O.sub.3, Al.sub.2O.sub.3,
V.sub.2O.sub.3, Ga.sub.2O.sub.3, Fe.sub.2O.sub.3, Mn.sub.2O.sub.3,
TiO.sub.2, Ti.sub.2O.sub.3, In.sub.2O.sub.3, TiBO.sub.3,
NiTiO.sub.3, MgTiO.sub.3, CoTIO.sub.3, ZnTiO.sub.3, FeTiO.sub.3,
MnTiO.sub.3, CrBO.sub.3, NiCrO.sub.3, FeBO.sub.3, FeMoO.sub.3,
FeSn(BO.sub.3).sub.2, AlBO.sub.3, Mg.sub.3Al.sub.2Si.sub.3O.sub.12,
NdAlO.sub.3, LaAlO.sub.3, MnSnO.sub.3, LiNbO.sub.3, LaCoO.sub.3,
MgSiO.sub.3, ZnSiO.sub.3 and Mn(Sb, Fe)O.sub.3. The metal oxide may
have a corundum-hematite crystal lattice structure as described in
U.S. Pat. No. 6,454,848 B2, or may be a host component having a
corundum-hematite crystalline structure which contains as a guest
component one or more elements selected from aluminum, antimony,
bismuth, boron, chromium, cobalt, gallium, indium, iron, lanthanum,
lithium, magnesium, manganese, molybdenum, neodymium, nickel,
niobium, silicon, tin, vanadium and zinc. A variety of
non-infrared-absorptive pigments are commercially available,
including mixed metal oxide pigments such as those supplied by
Ferro Corporation (Cleveland, Ohio) under the COOL COLORS.TM. and
ECLIPSE.TM. trademarks, for example V-778 COOL COLORS IR Black,
V-780 COOL COLORS IR Black, V-799 COOL COLORS IR Black, 10201
ECLIPSE Black, 10202 ECLIPSE Black and 10203 ECLIPSE Black; mixed
metal oxide pigments such as those supplied by Shepherd Color
Company (Cincinnati, Ohio) under the ARTIC.TM. trademark, for
example ARTIC Black 376, ARTIC Black 10C909, ARTIC Black 411 and
ARTIC Black 30C940; and mixed metal oxide pigments such as those
supplied by Tomatec America, Inc. (Florence, Ky.) under the numbers
42-707A and 707V710. The black pigments listed above, if used
alone, would not be expected to provide a colored vitreous enamel
coating. However, black pigments may be combined with colored
pigments to obtain darkened shades. The selection of a particular
pigment may depend in part upon the softening temperature of the
vitreous enamel and the heat stability of the individual pigment.
Not all pigments will have sufficient heat resistance to be used
with all glass frits or with all glass powder firing steps.
Sufficient pigment should be used to provide the desired degree of
coloration while maintaining adequate processability and final
properties in the vitreous enamel. Based on the final weight of the
vitreous enamel, the vitreous enamel may for example contain at
least about 0.1, at least about 0.2, at least about 0.5, at least
about 1, at least about 5 or at least about 10 weight % pigment,
and up to about 50, up to about 40, up to about 30 or up to about
20 weight % pigment.
[0067] As mentioned above, one or more colorants that become a part
of the glass and cause absorption of energy in a wavelength range
of interest may be added to the glass frit to provide coloration,
light scattering, and in preferred embodiments an opaque coating in
the final vitreous enamel. A variety of such colorants may be
employed, and will be familiar to persons having ordinary skill in
the glassmaking art. Exemplary colorants include many transition
metals and lanthanides and their oxides. For example, Co.sup.2+ ion
absorbs light at wavelengths of about 500 to 700 nm and reflects
blue light. Consequently, addition of cobalt oxide to the frit will
impart a blue coloration to the vitreous enamel. Iron(II) oxide or
chromium oxide may be employed to obtain bluish-green or green
coloration. In borosilicate glasses rich in boron, sulfur imparts a
blue color, and with calcium yields a deep yellow color. Manganese
can be added to provide an amethyst or violet coloration,
especially in the presence of sodium via formation of sodium
permanganate. Copper oxide may be employed to obtain turquoise
coloration. Nickel oxides may be used at various concentrations to
obtain blue, violet, or black glass. Chromium oxide may be employed
to obtain dark green or black coloration. Sufficient colorant
should be used to provide the desired degree of coloration while
maintaining adequate frit processability. Based on the final weight
of the vitreous enamel, the vitreous enamel may for example contain
at least about 0.1, at least about 0.2, at least about 0.5 or at
least about 1 weight % colorant, and up to about 30, up to about
20, up to about 10 or up to about 5 weight % colorant.
[0068] As mentioned above, color may also be imparted to a vitreous
enamel by selecting suitable flit ingredients or suitably
processing the molten enamel so as to form a visibly distinct
crystalline phase that scatters all wavelengths of light, resulting
in a white or off-white colored appearance. If color is imparted to
the vitreous enamel using other measures such as pigments or
colorants as discussed above, then crystallinity is not necessary
and the vitreous enamel composition may be an amorphous glass.
However, in other embodiments the vitreous enamel composition
includes a crystalline phase or additives that represent a
crystalline phase. For example, the vitreous enamel may include a
glass-ceramic composition. Glass-ceramic compositions may possess a
crystalline phase along with the amorphous glass. The crystallinity
of the vitreous enamel upon firing and formation may beneficially
enhance the opacity and light-scattering or absorption behavior of
the vitreous enamel. Non-limiting examples of crystalline phases
include Ca.sub.2ZnSi.sub.2O.sub.7 (hardystonite) car
Sr.sub.2SiO.sub.4. Other combinations of compounds, such as
nucleating agents, may be included in a glass frit and fired to
create a glass-ceramic composition with at least a partial
crystallinity that beneficially impacts the thermomechanical
properties of the vitreous enamel-coated electrosurgical cutting
blade. Crystallinity may also be imparted by adding to the glass
frit one or more separate crystalline glass additives such as
SIL-CEL.TM. 43 glass micro cellular fillers (from Silbrico
Corporation, Hodkins, Ill.), FILLITE.TM. 100 ceramic spherical
particles (from Trelleborg Fillite Inc., Norcross, Ga.),
SPHERICEL.TM. hollow glass spheres (from Potter Industries Inc.,
Valley Forge, Pa.), 3M ceramic microspheres including grades G-200,
G-400, G-600, G-800, W-210, W-410, and W-610 (from 3M, St. Paul,
Minn.) or 3M hollow microspheres including 3M Performance Additives
iM30K (also from 3M). Not all such crystalline glass additives will
have sufficient heat resistance to be used with all glass fits.
Sufficient crystallinity should be imparted to the vitreous enamel,
or sufficient crystalline glass additive should be added to the
glass fit, to provide the desired degree of coloration while
maintaining adequate frit processability. When a crystalline glass
additive is employed, and based on the final weight of the vitreous
enamel, the vitreous enamel may for example contain at least about
0.1, at least about 0.2, at least about 0.5, at least about 1, at
least about 5 or at least about 10 weight % crystalline glass
additive, and up to about 50, up to about 40, up to about 30 or up
to about 20 weight % crystalline glass additive. Expressed on a
volume basis, the glass used to prepare the vitreous enamel
preferably contains at least about 10, at least about 15, at least
about 20, at least about 30, at least about 40, at least about 50
or at least about 60 volume percent crystalline phase(s).
[0069] The chosen glass compositions may include other compounds to
impart or enhance certain features or characteristics such as glass
transition temperature (Tg), nucleation, water resistance, diffuse
reflection characteristics, CTE and dielectric properties. For
example, the glass may include additives to impart to the glass a
desired CTE as described in copending Application Serial No.
(attorney docket no. 4944.280WO01) filed even date herewith, or
ingredients to reduce specular reflection characteristics and
increase diffuse reflection characteristics as described in
copending Application Serial No. (attorney docket no. 4944.280WO03)
filed even date herewith. Exemplary and non-limiting examples of
other compounds that may be components of a glass frit to form the
vitreous enamel include the alkaline earth oxides mentioned above,
zinc oxide, magnesium oxide, sodium oxide, and potassium oxide.
Such compounds may optionally be included in the glass frit at
molar percentages ranging on a molar percentage from a trace, 0.1%,
1%, 2%, 5% or 10% up to about 5%, 10%, 15% 20%, 30% or 40%. The
frit desirably excludes materials that would not be biocompatible,
for example lead or other toxic metals and their oxides. Exemplary
glass hits and glasses include those from suppliers such as Elan
Technology, Ferro Corporation, Mo-Sci Corporation and Schott AG. In
a preferred embodiment, and before taking into account the addition
of refractory pigments, colorants or crystalline glass additives as
discussed above, a glass frit having the following compounds and
molar percentages may be well suited for forming a vitreous enamel
on an electrosurgical cutting blade: SiO.sub.2 30-50%,
B.sub.2O.sub.3 0.5-15%, Al.sub.2O.sub.3 0.5-10%, SrO 5-30%, CaO
5-30%, and ZnO 0.5-20%.
[0070] Without being bound by theory, it is believed that the
components in the disclosed vitreous enamel fit and vitreous enamel
coating offer various attributes. For example, the function of each
component in the glass composition may provide or offer certain
features to the resulting enamel, The Si.sub.2O helps form the
glass network. Modifiers such as alkali and alkaline earth oxides
may increase the CTE value and potentially decrease the glass
transition temperature. Al.sub.2O.sub.3 may modify the
crystallization rate. Minor additives such as TiO.sub.2 and
ZrO.sub.2 may act as nucleating agents. B.sub.2O.sub.3 may modify
the extent and rate of crystallization and improve wetting of the
glass to the metal substrate. B.sub.2O.sub.3 may also increase the
vitreous enamel CTE. High CTE partially crystallizing systems may
for example also include one or both of SrO and BaO. In some
embodiments the vitreous enamel has a CTE of about
6.times.10.sup.-6/.degree. C.; to about 16.times.10.sup.-6/.degree.
C. and more preferably about 10.times.10.sup.-6/.degree. C. to
about 12.times.10.sup.-6/.degree. C. The dielectric strength of the
vitreous enamel coatings may vary and in preferred embodiments may
be greater than about 20.000, about 30,000 or about 40,000 volts/mm
(about 508, about 762 or about 1016 volts/mil) as measured using
ASTM D149-09.
[0071] FIG. 6 is an illustration of one embodiment of a process 60
suitable for forming a vitreous enamel coating on an
electrosurgical cutting blade from a glass frit. The frit may be
separately-supplied or may be manually prepared just prior to use.
Glass melting step 62 is typically performed by mixing and melting
the frit components (including any refractory pigments, colorants
or crystalline glass additives) in a furnace and quenching 64 the
melt to form a solidified glass material. The resulting glass
material is then milled 66 to a desired particle size that will
support coating and formation of a vitreous enamel on the metal
substrate. Those of ordinary skill in the art will recognize that
particle size may have an impact on the properties of the resulting
vitreous enamel. In certain embodiments, the particles may have a
d.sub.90 value between about 20 and about 50 .mu.m (viz., 90 vol. %
of the particles may in such embodiments have an average diameter
below about 20 to below about 50 .mu.m). In an optional wet coating
step, a slurry 68 is prepared to facilitate the coating 70 of glass
powder onto the metal substrate. The slurry may for example be
prepared by dispersing the glass particles in a binder and carrier.
The carrier can be any suitable solvent that is capable of
maintaining a stable dispersion and a suitable viscosity for
coating. Non-limiting examples of suitable carriers include mineral
oil, ethanol, terpineol or combinations thereof. The binder
enhances wet out and coating of the metal substrate during the
coating process. Non-limiting examples of suitable binders include
polyvinyl butyral, polyvinyl alcohol, and ethyl cellulose.
Alternatively, the coating may be applied using a dry coating
process, thereby alleviating the need for slurry formation. In any
event, a variety of coating processes 70 may be employed.
Non-limiting examples include electrophoretic deposition, dip
coating, roll coating, spray coating or other similar application
processes. The coating is preferably applied at a thickness
sufficient to obtain a vitreous enamel coating that, after firing,
will not unduly degrade during plasma formation and preferably will
not suffer the defects that arise when using conventional vitreous
enamel coatings. In a preferred embodiment, the metal substrate is
coated to a vitreous achieve enamel coating thickness of about 75
.mu.m to about 100 .mu.m. In certain aspects in wet coating
processes, the viscosity of the slurry may be controlled to address
the coating thickness. Additionally, the coating is preferably
applied in a manner that provides an exposed or only thinly-coated
cutting edge. The edge may as discussed in connection with FIG. 3
be manually exposed by removing a portion of the vitreous enamel
coating. The selection of a particular coating process may be
dependent on various factors, including the metal substrate, the
size and geometry of the cutting blade, and the type of glass frit,
among others. Those of ordinary skill in the art will be capable of
matching a particular coating process to achieve a desired enamel
thickness on an electrosurgical cutting blade.
[0072] When using the slurry making step 68 and wet coating step 70
shown in FIG. 6, the binder and solvent are typically removed in a
binder burn-out step 72. The electrosurgical cutting blade may be
heated to a temperature and for a time sufficient to drive off any
binder and solvent from the glass powder. The duration and
temperature for this process may vary depending on the solvent or
binder composition. In some embodiments, the temperature ranges up
to about 500.degree. C. for a time up to about 60 minutes. After
this process, the remaining coating has green strength and ready
for glass firing to form a vitreous enamel.
[0073] The glass firing process 74 encompasses ramping up the
furnace temperature to the glass's firing temperature for a limited
time to form the vitreous enamel, fuse it to the substrate, and
anneal the final coating. Optionally, certain embodiments may allow
for the formation of a crystalline phase 76. The firing generally
takes place above 700.degree. C. and in some embodiments above
750.degree. C., or even above 800 .degree. C. The duration of the
firing process and the time the coated substrate is held at
temperature may for example vary depending upon the glass
composition, coating thickness, type of metal substrate, blade
shape and size, and other factors. Additionally, the let-down
temperature may vary and may be staggered to enable solidification,
annealing and stress relief. In certain embodiments, the annealing
temperature is established at or above the Tg value for the
selected vitreous enamel composition. The resulting vitreous
enamel-coated electrosurgical cutting blade may for example be very
similar in appearance to the embodiment shown in 2.
EXAMPLES
Examples 1 and 2
[0074] Colored vitreous enamel coatings on electrosurgical blades
were prepared by combining ground glass, refractory inorganic
pigments obtained, from Prince Minerals, a solvent and dispersant
in the amounts shown below in Table 1. The resulting mixtures were
ball milled for about two hours to ensure an appropriate level of
dispersion. The binder amount shown in Table 1 was added to the
mixture and ball milled for about 4 hours to create a slurry. The
viscosity of each slurry was measured using a Brookfield DV2T (LV)
viscometer and spindle SC4-18/13R, and maintained above 1500 cp at
0.2 rpm. Each slurry was applied onto 420 stainless steel
electrosurgical cutting blades using a dipping process. After the
slurry coating was applied, the coated blades were subjected to
burnout at About 600.degree. C. for more than 60 minutes and
subsequent firing at a temperature greater than 800.degree. C. for
more than 10 minutes. Upon the slow ramp down of the temperature to
room temperature, the vitreous enamel-coated electrosurgical blades
were visually inspected and photographed. Well-coated blades with
distinctive blue (Example 1) and green. (Example 2) coloration were
obtained. The blades could easily be distinguished from one another
based on the vitreous enamel color alone.
TABLE-US-00001 TABLE 1 Example 1, Example 2, Ingredient wt. % wt. %
Sr--Ca--Zn--Al--B--Si 55.1 55.1 alkaline earth aluminoborosilicate
glass powder P4055 blue pigment 5.0 P4020 green pigment 5.0
Toluene/ethanol solvent mixture 16.2 16.2 Triethyl phosphate
dispersant 1.1 1.1 Ethyl cellulose binder 22.6 22.6 Total 100
100
Example 3
[0075] A Sr--Ca--Zn--Al--B--Si alkaline earth aluminoborosilicate
glass like that employed in Examples 1 and 2 was prepared, but the
initial frit was modified by adding 2.36 wt. % cobalt oxide.
Following melting of the frit and grinding of the resulting glass
to form glass powder, a vitreous enamel-coated electrosurgical
blade was prepared using the method of Example 1 but without
addition of the refractory blue inorganic pigment. A well-coated
blade with a distinctive blue coloration like that obtained in
Example 1 was obtained.
Example 4
[0076] Coated blades with an even more intense coloration could be
obtained by using the blue glass prepared in Example 3 as the glass
powder in the blue-pigmented Example 1 slurry or green-pigmented
Example 2 slurry.
Example 5
[0077] Following the glass melting step, the glass employed in
Examples 1 and 2 was fired at 800.degree. C., 830.degree. C.,
850.degree. C. and 870.degree. C. for 15 minutes at each of these
temperatures. This produced a glass having two crystalline phases
that scattered light at all visible wavelengths. A vitreous
enamel-coated electrosurgical blade was prepared using the method
of Example 1 but without addition of the refractory blue inorganic
pigment. A well-coated blade with a distinctive white coloration
was obtained. FIG. 7 is an SEM image showing the crystalline
structure of the vitreous enamel coating.
[0078] Although specific embodiments have been illustrated and
described herein for purposes of description of the preferred
embodiments, it will be appreciated by those of ordinary skill in
the art that a wide variety of alternate or equivalent
implementations calculated to achieve the same purposes may be
substituted for the specific embodiments Shown and described
without departing from the scope of the present invention. This
application is intended to cover any adaptations or variations of
the preferred embodiments discussed herein. Therefore, it is
manifestly intended that this invention be limited only by the
claims and the equivalents thereof.
* * * * *