Electrosurgical electrode and method of manufacturing same

Abstract

An electrosurgical device coated an epoxy modified rigid silicone powder coating. This coating is applied to the surfaces of an electrosurgical device minimize the build-up of charred tissue (i.e., eschar) on the surfaces of the electrosurgical device.

Description

BACKGROUND

Electrosurgery refers to surgical procedures that pass high frequency, alternating electrical current through body tissues to cut or coagulate the tissues. Electrosurgical instruments or tools such as electrosurgical electrodes are used in these surgical operations to cut, coagulate and cauterize the tissue of a patient. The electrodes conduct the high frequency alternating electrical current from a generator to the patient to perform these operations. The generator is the source of the electricity for the surgical procedure. Because standard electrical current alternates at a frequency of sixty cycles per second (60 Hz), which could cause excessive neuromuscular stimulation and possibly electrocution if used, the generator takes sixty cycle current and increases the frequency to over 300,000 cycles per second (300,000 Hz). At this frequency, the electrical energy can pass through the patient with minimal neuromuscular stimulation and no risk of electrocution. Additionally, the generators are able to produce a variety of electrical waveforms. A constant waveform, which produces heat very rapidly, is generally used to vaporize or cut body tissue. An intermittent waveform produces less heat and is generally used to coagulate body tissue. Several different waveforms may used in an electrosurgical procedure to achieve different effects.

As described above, electrosurgical electrodes are used to cut or coagulate the body tissue in an electrosurgical procedure. Many sizes and shapes of electrosurgical electrodes such as blades, scalpels, needles, wire forms, balls and probes are available. Most electrosurgical electrodes are made of metal, typically stainless steel. Generally, a portion of the electrode is sheathed or encapsulated with an insulative material such as a plastic material. The electrodes are typically inserted into and connected to a handpiece for manipulating the electrode during surgery.

The working surface of the electrosurgical electrode or the exposed end of the electrode is not encapsulated with plastic or any type of electrically insulative material. The working surface generates heat and therefore is subject to high temperatures during use. The high temperature causes the body tissues to tend to stick to the working surface of the electrode. Specifically, the elevated temperature of the electrode causes charred tissue, commonly called “eschar,” to adhere or stick to the working surface of the electrode. The buildup of tissue or eschar on the working surface of the electrode negatively affects the performance of the electrode during surgery. In particular, a buildup of tissue on the electrode reduces the transfer of energy to and from the electrode which decreases the cutting effectiveness of the electrode. Additionally, the tissue buildup may obscure the vision of the surgeon and therefore make it more difficult to perform the surgery.

As a result, efforts are made during surgery to keep the working surface of the electrode clean. Such cleaning methods include rubbing, brushing or scraping the electrode surface against a scouring pad or other suitable cleaning device. The continuous cleaning of the surface of the electrode, however, prolongs the surgical procedure which is not desirable. Therefore, the surgeon is left with the options of replacing the electrode during surgery, accepting reduced performance of the electrode, or expending valuable time and energy in an attempt to thoroughly clean the surface of the electrode with an abrasive pad. If the surgeon must clean the surface of the electrode with an abrasive pad, as while scouring the coated surface of the blade, the surgeon must spend additional time and attention to not damage or wear through the protective coating.

One method used to solve the problem of tissue or eschar buildup on the surface of the electrode is to coat the surface of the electrode with a non-stick or surface release coating. The non-stick or release coating minimizes the sticking or adherence of the tissue on the surface of the electrode and enables the built up tissue to be removed more easily and efficiently from the surface.

Several different types of non-stick coatings have been used or suggested for application to electrosurgical electrodes. Some of the different non-stick coatings or materials include fluorinated hydrocarbon materials, polytetrafluoroethylene, perfluoro-alkoxy, flexible silicone elastomers, ceramic composites, paralyene silane polymers and other suitable non-stick coatings. Different methods exist for applying the non-stick coating to the surface of the electrosurgical electrodes. However, the non-stick or release coatings have varying degrees of electrically insulative qualities, and therefore, may change and/or impair the electrical conductivity of the surface of the electrodes. Some of such coatings are thinner (due to their inherent technical limitations and/or cost of production reasons) and thus posses less than optimum electrical and/or insulative properties. Other coatings provide discontinuous protection of the underlying metal blade and may contain micro fractures, holes and/or “holidays.” It should be appreciated that coating areas of reduced thickness and areas wherein the coating is missing alter the electrical insulative or surface characteristics of the electrical energy emitted from the surface of the coating, thus affecting the quality and consistency of the use of the blade. Such altered electrical insulative properties present an erratic and potential inconsistent function of the use of the electrosurgical device as a surgical tool.

Moreover, certain of these non-stick coatings, particularly the flouropolymers, may break down and emit harmful byproducts as the coated portion or portions of the electrosurgical electrode are heated to temperatures above 500° F. (260° C.). In addition to breaking down at temperatures above 500° F. (260° C.), as certain of these non-stick coatings approach 500° F. (260° C.), micro-fractures or fissures in the coating surface take place. These micro-fractures provide additional areas for eschar or carbonized organic matter to adhere to the electrosurgical device. As the coating breaks down due to thermal overheating of specific areas of the blade, particularly the edges and tip of the blade, the electrical insulative quality of the original coating is diminished and eventually destroyed. Accordingly, the user will need to change the electrical settings of the electrical generator or need to change to a new blade to achieve consistent end use results.

Another issue associated with surgical instruments such as electrosurgical electrodes is the cleanliness of the working surface and other surfaces of the electrode as the electrode contacts tissue and other parts of the body. The tissue or eschar buildup on the working surface of the electrode creates an environment where bacteria and other harmful organisms may cultivate and be introduced into the body during the surgical process. Furthermore, any gaps between the plastic sheath and the electrode or any fractures, fissures or other defects in the plastic sheath enables bacteria and other organisms to get underneath the plastic sheath and also into and grow in the fractures, fissures and defects or other interstices in the plastic sheath. This warm environment also promotes organism and bacteria growth. This further promotes the growth of the bacteria and the harmful organisms which may migrate to the surface of the electrode or to the patient. Bacteria forming on the eschar which in turn enters a patient's body during a surgical procedure can cause significant difficulties and complications for the patient after the surgical procedure is complete. As a result, minimizing the buildup of tissue or eschar and thus minimizing the growth of bacteria and other organisms on the electrode surface (and between the insulating sheath and the electrode shaft) is desirable to enable the electrode to be used multiple times to minimize and/or prevent infections or other related complications from developing in a patient following surgery.

Accordingly, there is a need for an improved electrosurgical device such as a single use or multi-use electrosurgical electrode and method of manufacturing same which minimizes the buildup of tissue on the substrate or working surface of the electrode during storage, use or pauses in the use of the electrode. Additionally, there is a need for an improved electrosurgical device which has superior easy-to-clean characteristics if the user desires to or must clean the electrosurgical device for multiple uses and/or store the previously used blades for future uses.

SUMMARY

The present disclosure relates in general to an electrosurgical electrode, and, specifically to an electrosurgical electrode coated with a specifically formulated epoxy modified rigid silicone powder non-stick coating and a method of manufacturing the same.

In one embodiment, an epoxy modified rigid silicone powder non-stick coating is applied to an electrosurgical device such as an electrosurgical blade, knife, wire, ball or other shape. In one embodiment, the electrosurgical device includes an electrode including a conductive substrate or conductive material where at least a portion of the electrode is encapsulated in a substantially electrically insulative material such as plastic, a handle connected to one end of the electrode and electrical conductors which are attached inside the handle to conduct electricity from an electrical source and deliver or transfer the electrical energy to the electrode. In one embodiment, the electrode conducts electrical energy to generate heat and cut, coagulate and/or cauterize tissue during a surgical procedure.

In one embodiment, the epoxy modified rigid silicone powder coating is applied uniformly and evenly to the surface or surfaces of the electrode to completely coat the exposed distal end or portion and a portion of the plastic encapsulated portion of the electrosurgical device. The epoxy modified rigid silicone powder has both high temperature capabilities and non-stick properties. The high temperature resistance of the epoxy modified rigid silicone powder enables the electrosurgical electrode to be heated to temperatures above which other non-stick coatings may break down and emit harmful byproducts. Accordingly, after multiple uses, the epoxy modified rigid silicone powder coating retains its hardness, surface toughness and non-stick properties on the electrode and the buildup of tissue or eschar on the working surface of the electrode is reduced or prevented.

In one embodiment, the electrosurgical device is coated with a silicone powder coating that is modified with an epoxy, which when applied to the electrosurgical device, forms a rigid or relatively hard silicone non-stick coating. In one embodiment, the epoxy modified rigid silicone powder coating includes a solid silicone resin and a polysiloxane additive. The silicone resin may be selected from the group including a phenyl polysiloxane powder resin, a methyl polysiloxane powder resin, a methyl phenyl siloxane powder resin, a phenyl silicone powder, a methyl phenyl silicone and a phenyl alkyl polysiloxane powder resin. The siloxane additive may be selected from the group including a methyl alkyl polysiloxane, a dimethyl polysiloxane and a methyl phenyl siloxane. It should be appreciated that any suitable epoxy or organic resin base combined with a suitable silicone powder with high temperature capabilities and non-stick properties (and possibly further modified with suitable organic materials and resins) may be implemented to advance or improve the end use high temperature and non stick properties of the disclosed powder coating technology.

In one embodiment, the epoxy modified rigid silicone powder coating includes:

(a) SY-430 in the range of about 40% to about 60% parts per weight of the powder coating;

(b) Wollastonite in the range of about 20% to about 40% parts per weight of the powder coating;

(c) ECN 9699 in the range of about 5% to about 15% parts per weight of the powder coating;

(d) Modarez MSL in the range of about 3% to about 7% parts per weight of the powder coating;

(e) HT 9690 in the range of about 0.5% to about 3% parts per weight of the powder coating; and

(f) Modaflow III in the range of about 0.5% to about 3% parts per weight of the powder coating.

In this embodiment, SY-430 is a resin made by Wacker-Chemie GmbH of Munich, Germany. According to the manufacturer, this product is a solvent-free hydroxyl functional solid phenyl silicone resin delivered in flake form.

Wollastonite is a naturally occurring calcium metasilicate (i.e., CaSiO₃). The particular Wollastonite product used in this embodiment is made by Nyco of Willsboro, N.Y., and is identified by that company as NYAD® 400 Wollastonite. According to the manufacturer, the deposit of calcium metasilicate came from Nyco's deposit in Lewis, Essex County, N.Y.

The ECN (“epoxy cresol novolac”) 9699 is an epoxy cresol novalac resin made by Ciba-Geigy. According to the manufacturer, this novolac epoxy resin is derived from an ortho cresolformaldehyde novolac which is then reacted with epichlorohydrin to form a polyepoxide.

The Modarez MSL is made by Synthron, Inc., Morganton, N.C. According to the manufacturer, this component is a 60% active powder version of the methyl alkyl polysiloxane for powder coatings.

The HT 9690 is a curing agent made by Ciba-Geigy. According to the manufacturer, this curing agent is an o-cresol novolac resin (hydroxyl-type).

The Modaflow® Powder III is made by the Chemical Group of Monsanto Company, St. Louis, Mo. This powder is an acrylate copolymer. According to the manufacturer, this powder is a resin modifier.

In alternative embodiments, in addition to the components described above, the epoxy modified rigid silicone powder coating may also include one or more the following pigments:

Micro-Mica C-300 in the range of about 0% to about 10% parts per weight of the powder coating;

(ii) Ferro F-6331 in the range of about 0% to about 10% parts per weight of the powder coating;

(I) Silvet 320-205 in the range of about 0% to about 6% parts per weight of the powder coating; and

(iv) Ferro UMB-5008 Blue in the range of about 0% to about 10% parts per weight of the powder coating.

In this embodiment, the Micro-Mica® C-3000 is an ultra-fine air micronized functional pigment consisting of pure muscovite mica distributed by Kraft Chemical Co. of Melrose Park, Ill.

The Ferro F-6331 is made by Ferro Corporation, Cleveland Ohio. It is a high temperature calcination of coprecipitated compound with manganese-copper-iron. According to the manufacturer, F-6331 is a black inorganic pigment. The CAS Number is 68186-94-7.

The Silvet 320-205 is made by Silberline World Headquarters of Tamaqua, Pa. It is a silvet pigment. According to the manufacturer, 320-205 is a small particle size bright leafing aluminum pigment based on cornflake geometry.

The Ferro UMB-5008 Blue is made by Ferro Corporation, Cleveland Ohio. It is an untramarine Blue inorganic pigment.

In one embodiment, the epoxy modified rigid silicone powder particles in the coating enable the electrosurgical device to reach a desired temperature quicker than conventional electrosurgical devices because the formulation of the rigid epoxy/silicone powder coating can be formulated with special pigments and additives to increase the thermal conductivity of the coated electrode surface compared to conventional polytetrafluoroethylene (PTFE) or elastomeric silicone coated electrode surfaces. As a result, electricity, electrical energy or heat is more effectively controlled and efficiently conducted or transferred to the electrode surface. Moreover, compared to elastomeric silicone coatings, in one embodiment, the epoxy modified rigid silicone powder may be ground to a finer mesh size for purposes of applying a thinner coating, thereby improving the thermal conductivity and coating flexibility without resulting in pinholes or fissures in the coating. In another embodiment, a thicker coating of the epoxy modified rigid silicone powder is applied to the electrosurgical device. Depending on the specific end use characteristics desired, such a thicker coating may be achieved by either formulating and manufacturing different particle sizes of the powder coating or through suitable coating application techniques.

In one aspect of this embodiment, the amount and density of epoxy modified rigid silicone powder particles (and additives, if any, used in a particular formulation) applied to the surfaces of the electrode is increased or decreased based on the desired electrical and heat conductivity of the electrosurgical device. The electrical and thermal conductivity can be altered when more epoxy modified rigid silicone powder particles are included in the coating, when less epoxy modified rigid silicone powder particles are included in the coating or when special pigments or additives are used to enhance one or more specific characteristics to further optimize the desired end use of the device. Additionally, the density and particle size of the epoxy modified rigid silicone powder particles applied to the surface of the electrode may be adjusted to increase or decrease the electrical conductivity. When the electrical conductivity of the electrode is increased, the temperature of the surface of the electrode is changed. This enables the coating mixture to be adjusted to optimize the desired end use of the device.

It should be appreciated that one or more combinations of different shaped epoxy modified rigid silicone powder particles may be used on the working surface of the electrosurgical electrode. Additionally, the density or thickness ranges of the epoxy modified rigid silicone powder particles may vary depending on the design specifications of an end product or final product. The density or distribution of the epoxy modified rigid silicone powder particles may vary from covering or adhering to approximately ten percent of the surface of the electrosurgical electrode to approximately sixty percent or more of the surface. Similarly, the density of the epoxy modified rigid silicone powder particles may vary depending on the end use criteria.

In another embodiment, one or more additional epoxy modified rigid silicone powder layers are applied to the first or primary epoxy modified rigid silicone powder layer applied to the surface of the electrosurgical device to meet specific design specifications or coating requirements of a manufacturer. The additional bonding material layers may be the same or different than the first epoxy modified rigid silicone powder layer and are applied to the first rigid silicone powder layer until a predetermined thickness is achieved. Additionally, different materials may be added to the bonding material layer or layers, based on specific design specifications. In another embodiment, different liquid bonding agents may be introduced to the top of the first layer of the epoxy modified rigid silicone powder before a second layer of the epoxy modified rigid silicone powder is attached to the first layer. This process may be repeated to build thicker layers of epoxy modified rigid silicone powder on all or a selective or individual portion of an electrosurgical device.

In one embodiment, prior to applying the epoxy modified rigid silicone powder to one or more surfaces of the electrosurgical device, the electrosurgical electrode is positioned on a support. Initially, the surface of the electrosurgical electrode is cleaned with a cleaner to remove impurities which may be present on the surface of the electrosurgical electrode. The cleaner such as a solvent may be manually applied or mechanically applied to the electrosurgical electrode. In one embodiment, grit blasting or sandblasting is used to clean the surface of the electrosurgical electrode. Alternatively, the electrosurgical electrode may be pre-cleaned or the method may be performed in a “clean room” where the cleaned part is manufactured and the step is not necessary. In another embodiment, the electrode is heated to a temperature, depending on the metal alloy of the electrode, in excess of 700° F. (371° C.) for a period of time sufficient to thermally degrade surface impurities. In another embodiment, the electrosurgical device may be cleaned in a batch or bulk cleaning method, thereby cleaning all of the surfaces of the electrosurgical device.

In one embodiment, the epoxy modified rigid silicone powder has self-adhesive properties. In this embodiment, when applied to the surfaces of the electrosurgical device, the epoxy modified rigid silicone powder particles will adhere. Thus, in this embodiment, no bonding layer is necessary to be applied to the electrode.

In another embodiment, the epoxy modified rigid silicone powder particles must be affixed to one or more surfaces of the electrosurgical device using one or more wet bonding materials. In this embodiment, after the surface of the electrosurgical electrode is cleaned, a layer of a wet bonding material such as a primer is applied to one or more surfaces of the electrosurgical device. The layer of wet bonding material is preferably applied uniformly so as to avoid forming a thick layer, which is thicker than what is necessary or required, and avoid drippings which may detract from the bonding ability to the electrosurgical device.

In one embodiment, the bonding material layer may be formulated to improve the bonding capabilities of the subsequent epoxy modified rigid silicone powder coating layer or layers applied to the surface of the electrosurgical electrode. In this embodiment, the wet bonding material may include one or more additives which change or enhance one or more characteristics of the wet bonding material. For example, in one embodiment, the wet bonding material includes an ultraviolet light cure resin to semi or fully cure the bonding layer. In another embodiment, the wet bonding material includes an electron beam cure resin. It should also be appreciated that the bonding material may be any suitable bonding material or agent. For example, a thin layer of any suitable epoxy may be utilized as the bonding layer to coat the surface of the electrode prior to the application of the epoxy modified rigid silicone powder.

In one embodiment, while the bonding material layer is still wet, a single layer of epoxy modified rigid silicone powder is sprayed over the wet bonding material. In one embodiment, a substantially uniform layer of epoxy modified rigid silicone powder is applied to the wet bonding material. The epoxy modified rigid silicone powder particles adhere to the wet surface area of the bonding material in an even manner. In this embodiment, when the wet bonding material is completely coated with one layer of the uniform epoxy modified rigid silicone powder mixture of particles, additional epoxy modified rigid silicone powder particles cannot stick to the bonding material layer because the insulative qualities of the adhered epoxy modified rigid silicone powder particles attached to the bonding material layer act as a barrier to other particles attaching to the wet bonding material layer. Therefore, the epoxy modified rigid silicone powder particles do not build up or form an uneven surface area on the surface of the electrosurgical electrode. Additionally, the wet bonding material layer may be a thick layer where the uniform epoxy modified rigid silicone powder particles sink into and are completely covered by the wet bonding material layer. In another embodiment, the wet bonding material layer is a substantially thin layer on the surface of the electrosurgical device and a substantial portion of the epoxy modified rigid silicone powder particles are exposed on the wet bonding material layer.

In another embodiment, an electrostatic, tribo-charged or opposite electrostatic charged powder spray method is used to apply the epoxy modified rigid silicone powder particles to either a dry electrosurgical device or an electrostatic device coated with the wet bonding adhesion promoting material. In one embodiment, the wet bonding agent is from the epoxy resin family. The electrostatically charged particle powder spray enables an operator to better control the application uniformity of the epoxy modified rigid silicone powder particles and thereby enhance the uniformity, density and application of the epoxy modified rigid silicone powder particles to the wet bonding material on the electrosurgical device. It should be appreciated that the epoxy modified rigid silicone powder particles may have one or more surface characteristics altered to allow for more efficient electrostatic, tribo-charged or opposite electrostatic charged powder spray techniques to be used to apply the epoxy modified rigid silicone powder particles to an electrosurgical device.

Moreover, the above-described “tribo-charge” application technique alters the edge coverage thickness of the applied powder based on any design requirements which require a more uniformly applied epoxy modified silicone nonstick powder to all surfaces of the device, whether the configuration has sharp or round edges. This technique results in optimizing the different edge coverage thicknesses of the applied epoxy modified rigid silicone powder, whether the electrosurgical device is a blade, ball, wire or a different shape.

It should be appreciated that an electrosurgical device manufactured with an epoxy modified rigid silicone powder coating exhibits improved uniformity of coating thickness and coverage of the critical edge or tip characteristics. In one embodiment, due at least in part to the “Farraday” effect of applying increased amounts of coatings to a sharp corner or edge, electrostatically applied epoxy modified rigid silicone powder particles are more easily applied to and attach to the thin or sharp edges of the electrosurgical device. In this embodiment, by altering the electrostatic powder coating equipment or techniques of application, such as by changing the power settings, waveforms and/or other electrical characteristics of the application equipment, the edges of the electrosurgical device are selectively more or less heavily coated with the epoxy modified rigid silicone powder.

After the epoxy modified rigid silicone powder coatings are applied to the surfaces of the electrode, the coatings are cured in a suitable device, such as an oven or furnace, or by using a suitable curing method or process. The curing process hardens the coatings and promotes the adherence of the coatings to the electrode. The coated electrode, therefore, minimizes the build up of eschar on the surfaces of the coated electrosurgical device.

In one embodiment, in addition to the epoxy modified rigid silicone powder particles, a plurality of anti-microbial particles such as silver, silver ceramic, silver oxide or silver compounds or any suitably anti-microbial agent are applied to one or more of the surfaces of the electrosurgical device to reduce and kill bacteria and other potential germs that may be located on the surface(s) of the electrosurgical device. In one aspect of this embodiment, the anti-microbial particles are interspersed with the epoxy modified rigid silicone powder particles and a layer of anti-microbial material is applied to the electrosurgical device along with the epoxy modified rigid silicone powder particles. The above process can be repeated as necessary to maintain the effectiveness of the anti-microbial surface. The addition of the anti-microbial material tends to kill bacteria or other harmful organisms that contact the surface of the electrode during and after the surgical procedure. This coated electrode may be used multiple times in different surgical procedures without requiring sterilization (even though sterilization is preferred) because the anti-microbial particles are capable of killing the bacteria and other harmful organisms which contact the surfaces of the electrode. The coated electrosurgical device therefore minimizes or reduces the chance of infections or other complications in the body after the surgical procedure is complete.

It is therefore an advantage of the present apparatus and method to provide an epoxy modified rigid silicone powder coating to the surface of an electrosurgical device to prevent the build up of tissue on the device.

A further advantage of the present apparatus and method is to provide a epoxy modified rigid silicone powder coating to the surface of an electrosurgical device to enable the device to be used multiple times in different surgical procedures.

Another advantage of the present apparatus and method is to provide an electrosurgical device that is coated with a epoxy modified rigid silicone powder to enable the device to be heated to temperatures at which other non-stick coatings break down and lose their non-stick properties, wherein in the process of decomposing, such other non-stick coatings generate toxic and noxious gasses and harmful airborne particles.

Another advantage of the present apparatus and method is to provide an electrosurgical device coated with a powder coating which includes a silicone resin and siloxane additive without any fluoropolymers.

Additional features and advantages of the present apparatus and method are described in and will be apparent from, the following Detailed Description and the Figures.

BRIEF DESCRIPTION OF THE FIGURES

The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the U.S. Patent and Trademark Office upon request and payment of the necessary fee.

FIG. 1 is a front perspective view of one embodiment of a coated electrosurgical instrument.

FIG. 2A is a cross-section view of the embodiment of FIG. 1 taken generally along the line 2A-2A.

FIG. 2B is a cross-section view of the embodiment of FIG. 1 taken generally along the line 2B-2B.

FIG. 3A is a cross-section view of another embodiment of the electrosurgical instrument of FIG. 1 taken generally along the line 3A-3A where a primer or base coating is applied to the surfaces of the instrument.

FIG. 3B is a cross-section view illustrating the embodiment of FIG. 3A, including a layer of epoxy modified rigid silicone powder particles.

FIG. 3C is a cross-section view of FIG. 3B, including a top coating applied to the layer of epoxy modified rigid silicone powder particles.

FIG. 3D is a cross-section view of the embodiment of FIG. 3C taken generally along the line 3D-3D.

FIGS. 4A and 4B are color photographs illustrating stages of degradation of an electrosurgical device coated with polytetrafluoroethylene compared to an electrosurgical device coated with an epoxy modified rigid silicone powder.

FIGS. 5 to 8 are color photographs illustrating the results of a comparative wear test between laparoscopic blades coated with PTFE DuPont Teflon and laparoscopic blades coated with epoxy modified rigid silicone powder particles.

FIGS. 9 to 12 are color photographs illustrating the results of a comparative “liver cutting test” between laparoscopic blades coated with PTFE DuPont Teflon and laparoscopic blades coated with epoxy modified rigid silicone powder particles.

FIGS. 13 and 14 are color photographs illustrating the results of a surgical gauze pad wiping after a comparative “liver cutting test” between laparoscopic blades coated with PTFE DuPont Teflon and laparoscopic blades coated with epoxy modified rigid silicone powder particles.

FIG. 15A is a table (shown as Table 1) illustrating the results of a total of 50 test blades, organized into groups of five blades, which were “pull” tested to determine the average weight loss.

FIG. 15B is a graph (shown as Graph 1) illustrating the results of the total of 50 test blades, organized into groups of five blades, which were “pull” tested to determine the average weight loss of Table 1.

FIG. 16A is a table (shown as Table 2) illustrating the average wear (in inches) of the 851-204 Teflon®-coated blade and the rigid epoxy silicone material coated blade after fifty withdrawals through the scratch pad.

FIG. 16B is a graph (shown as Graph 2) illustrating the average wear (in inches) of the 851-204 Teflon®-coated blade and the rigid epoxy silicone material coated blade after fifty withdrawals through the scratch pad of Table 2.

FIG. 17 is a table (shown as Table 3) illustrating the results of a comparative “liver cutting test” (i.e., a simulated medical procedure) which showed the eschar buildup on the 851-204 Teflon®-coated blade after the test and the eschar buildup on the rigid epoxy silicone material coated blade after the test.

DETAILED DESCRIPTION

Referring now to FIG. 1, one embodiment is illustrated where a coating of epoxy modified rigid silicone powder is applied to an electrosurgical device such as an electrosurgical instrument, blade or knife 100. In this embodiment, the coated electrosurgical instrument 100 includes an electrode 102 and a holding device such as handle 104 or other suitable holding device which is connected to the electrode 102 and enables the electrode to be manipulated in a surgical procedure. The electrode includes a conductive substrate or conductive material which enables the electrode to conduct electrical energy or electricity. In one embodiment, a portion of the electrode 102 is coated, encapsulated or over-molded with an electrically insulative material 103 such as a suitable plastic. The coated electrode 102 includes a distal end or working end 106 and a proximal end or connection end 107 which may be bare metal and is not coated with any coating material. The exposed distal end 106 of the electrode is used to cut, coagulate and/or cauterize tissue in a body during a surgical procedure. Specifically, electrical energy such as electricity is transferred from a suitable electrical source through suitable wiring to electrical conductors (not shown) inside the handle 104. The electrical energy is then transferred from the conductors (not shown) in the handle 104 to the proximal end 107 of the electrode 102, which is electrically connected to the conductors in the handle, and energizes the electrode 102. Once energized, the electrical and thermal energy produced by the electrically charged electrode generates an elevated temperature which enables the distal end 106 of the electrode to cut, coagulate and/or cauterize tissue in a body.

In one embodiment, an epoxy modified rigid silicone powder coating is evenly applied to the entire surface of the electrode to minimize the buildup of tissue or eschar on the working surface of the electrode. The epoxy modified rigid silicone powder coating has high temperature capabilities (i.e., a melting temperature of approximately 900° F. (482° C.)) and non-stick properties such that the electrosurgical electrode may be heated to temperatures above which other fluoropolymer based non-stick coatings may break down and emit harmful and toxic ganeous byproducts. Accordingly, the rigid silicone coating minimizes the buildup of tissue or eschar on the surface of the electrode by minimizing the adherence of the tissue on the surface of the electrode. Specifically, the epoxy modified rigid silicone powder coating forms a non-stick surface which reduces or prevents eschar from adhering to the surface coated with the epoxy modified rigid silicone powder. This enables a user such as a surgeon to continue a surgical procedure without having to continuously clean, scrape or brush off adhered charred tissue from the surface of the electrode.

In one embodiment, the epoxy modified rigid silicone powder coating includes a silicone resin and a polysiloxane additive. The silicone resins may be selected from the group including a phenyl polysiloxane powder resin, a methyl polysiloxane powder resin, a methyl phenyl polysiloxane powder resin, a phenyl alkyl polysiloxane powder resin, a methyl phenyl polysiloxane powder resin, a phenyl silicone powder and a methyl phenyl silicone. The siloxane additive includes a polysiloxane additive selected from the group consisting of a methyl alkyl polysiloxane, a dimethyl polysiloxane and a methyl phenyl siloxane. It should be appreciated that any suitable epoxy modified rigid silicone powder with high temperature capabilities and non-stick properties may be implemented.

In one embodiment, the polysiloxane additive is between about 0.5% to about 10% parts per weight of the powder coating. In one embodiment, the silicone resin is from about 5% to 75% parts per weight of the powder coating. In another embodiment, the powder coating includes epoxy cresol novolac. In this embodiment, the epoxy cresol novolac is from about 1% to about 50% parts per weight of the powder coating. In another embodiment, the powder coating includes o-cresol novolac. In this embodiment, the o-cresol novolac is from about 1% to about 40% parts per weight of the powder coating. In another embodiment, the powder coating includes a solid bisphenol-A/epichlorohydrin epoxy resin. In this embodiment, solid bisphenol-A/epichlorohydrin epoxy resin is from about 1% to about 50% parts per weight of the powder coating.

In one embodiment, the epoxy modified rigid silicone powder coating includes:

(a) SY-430 in the range of about 40% to about 60% parts per weight of the powder coating;

(b) Wollastonite in the range of about 20% to about 40% parts per weight of the powder coating;

(c) ECN 9699 in the range of about 5% to about 15% parts per weight of the powder coating;

(d) Modarez MSL in the range of about 3% to about 7% parts per weight of the powder coating;

(e) HT 9690 in the range of about 0.5% to about 3% parts per weight of the powder coating; and

Modaflow® Powder III in the range of about 0.5% to about 3% parts per weight of the powder coating.

In this embodiment, SY-430 is a resin made by Wacker-Chemie GmbH of Munich, Germany. According to the manufacturer, this product is a solvent-free hydroxyl functional solid phenyl silicone resin delivered in flake form.

Wollastonite is a naturally occurring calcium metasilicate (i.e., CaSiO₃). The particular Wollastonite product used in this embodiment is made by Nyco of Willsboro, N.Y., and is identified by that company as NYAD® 400 Wollastonite. According to the manufacturer, the deposit of calcium metasilicate came from Nyco's deposit in Lewis, Essex County, N.Y.

The ECN (“epoxy cresol novolac”) 9699 is an epoxy cresol novalac resin made by Ciba-Geigy. According to the manufacturer, this novolac epoxy resin is derived from an ortho cresolformaldehyde novolac which is then reacted with epichlorohydrin to form a polyepoxide.

The Modarez MSL is made by Synthron, Inc., Morganton, N.C. According to the manufacturer, this component is a 60% active powder version of the methyl alkyl polysiloxane for powder coatings.

The HT 9690 is a curing agent made by Ciba-Geigy. According to the manufacturer, this curing agent is an o-cresol novolac resin (hydroxyl-type).

The Modaflow® Powder III is made by the Chemical Group of Monsanto Company, St. Louis, Mo. This powder is an acrylate copolymer. According to the manufacturer, this powder is a resin modifier.

In alternative embodiments, in addition to the components described above, the epoxy modified rigid silicone powder coating may also include one or more the following pigments:

(i) Micro-Mica C-300 in the range of about 0% to about 10% parts per weight of the powder coating;

(ii) Ferro F-6331 in the range of about 0% to about 10% parts per weight of the powder coating;

(I) Silvet 320-205 in the range of about 0% to about 6% parts per weight of the powder coating; and

(iv) Ferro UMB-5008 Blue in the range of about 0% to about 10% parts per weight of the powder coating.

In this embodiment, the Micro-Mica® C-3000 is an ultra-fine air micronized functional pigment consisting of pure muscovite mica distributed by Kraft Chemical Co. of Melrose Park, Ill.

The Ferro F-6331 is made by Ferro Corporation, Cleveland Ohio. It is a high temperature calcination of coprecipitated compound with manganese-copper-iron. According to the manufacturer, F-6331 is a black inorganic pigment. The CAS Number is 68186-94-7.

The Silvet 320-205 is made by Silberline World Headquarters of Tamaqua, Pa. It is a silvet pigment. According to the manufacturer, 320-205 is a small particle size bright leafing aluminum pigment based on cornflake geometry.

The Ferro UMB-5008 Blue is made by Ferro Corporation, Cleveland Ohio. It is an untramarine Blue inorganic pigment.

It should be appreciated that in addition to or as a substitution for any of the pigments described above, any suitable pigment may be implemented in accordance with the epoxy modified rigid silicone powder coated electrosurgical device disclosed herein. In another alternative embodiment, hydroxyl functional methyl phenyl polysiloxane may be used in place of the SY-430 described above.

In one specific, designated embodiment, the epoxy modified rigid silicone powder coating includes:

(a) about 50% parts per weight of SY-430;

(b) about 23.5% parts per weight of Wollastonite;

(c) about 10% parts per weight of ECN 9699;

(d) about 5% parts per weight of Micro-Mica® C-3000;

(e) about 5% parts per weight of Modarez MSL;

(f) about 4% parts per weight of Ferro F-6331;

(g) about 1.5% parts per weight of HT 9690; and

(h) about 1% parts per weight of Modaflow® Powder III.

It should be appreciated that the epoxy modified rigid silicone powder coating may include any suitable or equivalent chemical composition, including the chemical compositions described in U.S. Pat. No. 5,691,067 (which relates to powder coatings for cookware and bake ware and not an electrosurgical electrode) which is incorporated herein by reference.

In one alternative embodiment, the epoxy modified rigid silicone powder coating includes C.I. Pigment 50 green in the range of about 1% to about 15% parts per weight of the powder coating. In this embodiment, the C.I. Pigment 50 green is a green pigment produced by The Shepherd Color Company, Cincinnati, Ohio. The C. I. Pigment 50 green is a complex inorganic colored pigment manufactured from crystals of metal oxide and is Food Contact Approved. In another alternative embodiment, the epoxy modified silicone powder coating includes a blending in about 1-15% by weight of TiO2 (titanium dioxide) as a white pigment in combination with green pigment, Ferro Geode V-11633 within a range of from 1 to 15% by weight of Green Ferro Geode V-11633 pigment.

As the properly formulated and/or reformulated epoxy modified rigid silicone coating has an optimized or altered electrical conductivity, the epoxy modified rigid silicone powder particles applied to the surface of the electrode more evenly distributes the temperature and electrical energy transferred to the electrode while increasing the electrical conductivity of the electrode. The increase and relatively even distribution of electrical energy or electricity to the electrode enables the electrode to minimize “hot spots” or portions of the electrode which have a higher temperature due a disproportionate or non-uniform distribution of the electrical energy to the electrode. As a result, a surgeon can make more precise cuts or coagulate or cauterize discrete or specific parts of the tissue in the body with more accuracy. This improves the surgical procedure and also minimizes the time of the surgical procedure. The amount of or density of the epoxy modified rigid silicone powder particles or compounds included in the coating can be adjusted to increase or decrease the conductivity of the coating applied to the surface of the electrode. In another embodiment, electrically conductive pigments may be blended into the formulation to further enhance electrical energy transmission from the electrode thru the rigid silicone coating.

In one embodiment, the size of the epoxy modified rigid silicone powder particles may be changed as desired to accommodate different technical and coating requirements or specifications. In one embodiment, the epoxy modified rigid silicone powder particles include at least one relatively large particle and at least one relatively small particle. In another embodiment, the epoxy modified rigid silicone powder particles range in size such as from a sub-micron to approximately 125-150 microns. the epoxy modified rigid silicone particle layers are substantially spherical particles, which creates a softer, less abrasive surface on the electrosurgical device.

In another embodiment, the uniform particle layer includes different sized epoxy modified rigid silicone powder particles applied to the surface of the electrosurgical device. In one example, hard abrasion resistant larger size particles and smaller electrically conductive particles are applied to create an abrasion resistant and electrically conductive surface of the electrosurgical device. It should be appreciated that any suitably sized and shaped epoxy modified rigid silicone powder particles may be applied to the surface of the substrate.

In one embodiment, prior to applying the epoxy modified rigid silicone powder to one or more surfaces of the electrosurgical device, the electrosurgical electrode is positioned on a support. Initially, the surface of the electrosurgical electrode is cleaned with a cleaner to remove impurities which may be present on the surface of the electrosurgical electrode. The cleaner such as a solvent may be manually applied or mechanically applied to the electrosurgical electrode. In one embodiment, grit blasting or sandblasting is used to clean the surface of the electrosurgical electrode. In one alternative embodiment, rather than grit blasting, an ultrasonic liquid cleaner is used to clean the electrosurgical electrode. In this embodiment, the ultrasonic liquid cleaner strips a microscopic layer off the top surface of the electrode. In another embodiment, the electrosurgical electrode may be thermally cleaned by heating the electrode to a temperature, depending on the metal alloy of the electrode, in excess of 700° F. (371° C.) for a period of time sufficient to thermally degrade surface impurities. In another alternative embodiment, the electrosurgical electrode may be pre-cleaned or the method may be performed in a “clean room” where the cleaned part is manufactured and this cleaning step is not necessary. In another embodiment, the electrosurgical device may be cleaned in a batch or bulk cleaning method, thereby cleaning all of the surfaces of the electrosurgical device.

In one embodiment, the epoxy modified silicone powder coating mixture formulation has self-adhesive properties. In this embodiment, when applied to the surfaces of the electrosurgical device, the epoxy modified rigid silicone powder particles will adhere. Thus, in this embodiment, no bonding layer is necessary to be applied to the electrode after the electrode is cleaned. In another embodiment, a silane coupling agent which is only a few molecules thick is used prior to the application of the epoxy modified rigid silicone powder. In this embodiment, the silane coupling or adhesion promoting agent remains wet on the electrode surface, the dry epoxy modified rigid silicone powder is applied directly to it and the electrode is cured once. One or more suitable powder topcoats may then be applied to the cured electrode, with or without suitable liquid coupling or bonding agents.

In one embodiment, a very thin liquid epoxy-based material is applied to the electrosurgical device after the electrode surface is cleaned but prior to the application of the epoxy modified rigid silicone powder particles. In another embodiment, prior to the application of the epoxy modified rigid silicone powder particles, a very thin liquid epoxy-based material is applied to the cleaned electrode surface and the electrode surface is semi-dried or semi-cured. The liquid layer of epoxy remains wet during the application of the dry powder particles. These embodiments provide increased adhesion of the epoxy modified rigid silicone powder particles to the electrosurgical device by creating a linking or bonding agent between the electrosurgical device and the subsequently applied epoxy modified rigid silicone powder particles.

In an alternative embodiment, the liquid epoxy-based material includes one or more colored pigments, such as a red pigment color or a yellow pigment color. The subsequently applied epoxy modified rigid silicone powder particles include a different colored pigment, such as a black pigment color. In this embodiment, as a surgeon sanded the blade with a scratch pad (in order to remove the adhered eschar) and eventually wore thru the epoxy modified rigid silicone powder topcoat (i.e., the black colored layer), the surgeon would see the underlying red colored layer and thus be notified that it was time to change the blade as the non-stick layer is at least partially worn off or worn thru.

In another embodiment, the epoxy modified rigid silicone powder particles must be affixed to one or more surfaces of the electrosurgical device using one or more bonding materials. In this embodiment, after the electrosurgical device is cleaned or is clean, a layer of a substantially wet bonding material is applied to the electrosurgical device. The bonding material provides a wet or moist surface for the subsequent substantially uniform rigid silicone particle layer to adhere to. The wet bonding material may be any suitable bonding material, which meets the specific design specifications of the particular electrosurgical device. In one embodiment, it is important that the bonding material remain wet prior to the application of the rigid silicone particle layer so that the epoxy modified rigid silicone powder particles stick to or adhere to the wet bonding material. In this embodiment, a single layer of substantially uniform epoxy modified rigid silicone powder particles are applied or powder sprayed onto the wet bonding material layer until the wet bonding material layer is completely coated with the dry uniform particles and a desired thickness is achieved. The thickness of the coatings or coating layers is dependent on the specifications for the particular product, the amount of bonding material applied and the size and shape of the epoxy modified rigid silicone powder particles. It should be further appreciated that the epoxy modified rigid silicone powder particles may be applied to the electrosurgical device utilizing any of the processes described in published U.S. Patent Application No. 2004/0116792 which is incorporated herein by reference.

It should be appreciated that due to the manner that PTFE is applied to a blade (i.e., via one or more liquid coatings), a PTFE coated blade includes a number of small holes in the PTFE coating. Such holes or inconsistencies may disrupt the non-stick characteristics of a PTFE coated blade. On the other hand, because the epoxy modified rigid silicone powder particles are applied, as described above, as a dry powder, a greater portion of the coating adheres to the blade and no small holes are present in the coating. It should be further appreciated that a thicker layer of coating may be applied to an epoxy modified rigid silicone coated blade than a PTFE coated blade at substantially the same cost. That is, PTFE can only be applied to a certain level of thickness because any thickness over that level and the PTFE coating develops “mud” cracks. On the other hand, epoxy modified rigid silicone is mechanically stronger than PTFE and thus a thicker layer of epoxy modified rigid silicone may be applied to a blade without cracking. It should also be appreciated that the epoxy modified rigid silicone composition described above is recyclable.

In one embodiment, the epoxy modified rigid silicone powder particles are sprayed or applied onto the wet bonding material as a single substantially uniform and substantially even layer which adheres to the sticky or wet surface of the bonding material. In another embodiment, the electrosurgical device is electrically grounded using a suitable grounding method. Electrically grounding the electrosurgical device thereby grounds the wet bonding material layer, which is formulated to include solvents and/or liquids that conduct electrical energy. The substantially uniform epoxy modified rigid silicone powder particle layer has or will have an opposite electrical charge to that of the bonding material layer and therefore is electrically or electrostatically attracted to the wet bonding material layer as the epoxy modified rigid silicone powder particles are applied to that layer. In a further embodiment, an applicator such as a sifter or electrostatic fluidized bed is used to uniformly apply the epoxy modified rigid silicone powder particles to the wet bonding material layer. The sifter is similar to a conventional flour sifter or a drum sifter and is used in certain applications depending on the required application of the uniform particles. The electrostatic fluidized bed contains a porous membrane made of porous polyethylene or any suitable electrically non-conductive material which allows the aeration of the powder with pressurized air that is charged to approximately 60,000 volts with a metal grid under the porous membrane, thereby charging the epoxy modified rigid silicone powder particles. Charging the epoxy modified rigid silicone powder particles cause the particle to adhere to the grounded electrosurgical device placed above or in the fluidized bed.

After the substantially uniform epoxy modified rigid silicone particle layer is applied to the wet bonding material layer, the layer is cured to strengthen the bond between the uniform rigid silicone particle layer and the wet primer layer on the surface of electrosurgical device. The curing process may be performed by heating the layers at a predetermined temperature or temperatures, air-drying the layers or by utilizing any suitable internal or external curing process. When the substantially uniform epoxy modified rigid silicone powder particle layer has completed adhered or bonded to the bonding material layer, a suitable coating layer may be applied to the uniform epoxy modified rigid silicone powder particle layer. In this embodiment, the epoxy modified rigid silicone powder coating may be undercured in an oven or suitable device, thus creating a semi-cured layer to which subsequent liquid or epoxy modified rigid silicone powder layers may be attached with a final cure which will consolidate the multiple layers. The coating may be any suitable coating such as a topcoat or final coat material. Examples include corrosive or abrasive resistant coatings, non-stick coatings or low friction coatings, anti-microbial coatings and electrically insulative or conductive coatings or combinations thereof. It should be appreciated that areas of the electrosurgical device in which epoxy modified rigid silicone powder is not required can be vacuumed or mechanically wiped from the electrosurgical device prior to the oven curing of the coating. This saves much production time and further reduces production costs.

In one embodiment, the metal electrosurgical blade or device is heated to a temperature in excess of 500° F. (260° C.) using induction heating or other suitable heating methods. A portion of the electrosurgical device that is to be powder coated is immersed into a non-electrostatic fluidized bed up to the point where the coating is not required and held there for a period of time between one half second to approximately 10 seconds. A layer of epoxy modified rigid silicone powder particles will adhere to the portion of the electrosurgical device that has been immersed into the fluidized bed of the powder. The electrosurgical blade or device is then placed into a fixture or onto a conveyor device and passed through a heating chamber to finish cure the layer of epoxy modified rigid silicone powder particles. It should be appreciated that this technique reduces the amount of masking or fixturing required for powder spraying the same type of parts, particularly if the parts have complex shapes and/or blind cavities or recesses.

FIGS. 2A and 2B illustrate one embodiment of the electrosurgical blade 100 of FIG. 1 wherein a single even layer of epoxy modified rigid silicone powder particles 112 with self-adhesive properties is applied directly to the surface of the electrode 102 without the use of any bonding material layer. The electrode 102 includes major surfaces 108 and minor surfaces 110. The rigid silicone particle coating is uniformly and evenly applied to the major surfaces 108 and minor surfaces 110 of the electrode as shown in FIG. 2A. In this embodiment, the rigid silicone coating enables the electricity or electrical energy to be evenly conducted and displaced across the surfaces of the electrode. This provides substantial benefits in a surgical process by minimizing the buildup of tissue or eschar on the surface of the electrode thus reducing surgical time and possibly minimizing the likelihood of complications arising during surgery.

FIGS. 3A, 3B and 3C illustrate another embodiment of the electrosurgical blade 100 of FIG. 1 wherein a single even layer of epoxy modified rigid silicone powder particles 112 is applied to the surface of the electrode 102 with the use of any suitable bonding material layer 114. In this embodiment the major surfaces 108 and minor surfaces 110 of the electrode are initially roughened to promote the adherence of the coatings to the surfaces. After the surfaces are roughened or suitably cleaned, a wet bonding material such as a primer 114 is applied to the major surfaces 108 and minor surfaces 110 of the electrode. The wet bonding material is applied evenly and uniformly to the surface of the electrode. While the wet bonding material is still substantially wet, a plurality of epoxy modified rigid silicone powder particles 112 are applied to the wet bonding material 114 as shown in FIG. 3B and as disclosed above. The dry epoxy modified rigid silicone powder particles engage, adhere to and are at least partially embedded in the wet bonding material 114. The wet bonding material 114 therefore causes the epoxy modified rigid silicone powder particles 112 to adhere to and enhance the adhesion of the epoxy modified rigid silicone powder particles to the surface of the electrode 102.

In one embodiment, a top coating 116 is applied over the layer of epoxy modified rigid silicone powder particles 112 so that the top coating completely and fully coats the layer of epoxy modified rigid silicone powder particles on the surface of the electrode. This top coating may be applied to a semi-cured epoxy modified rigid silicone powder prior to the final bake. As shown in FIG. 3C, the top coating 116 is applied so that the epoxy modified rigid silicone powder particles are exposed at the surfaces of the electrode. Therefore, the electrosurgical electrode retains the benefits of minimizing the buildup of tissue or eschar on the surface of the electrode. In this embodiment, the top coating is not applied to the surfaces of the electrode covered by the insulative or plastic material 103 as shown in FIG. 3D. This fully exposes the maximum amount of epoxy modified rigid silicone powder particles underneath at least a portion of the insulative material 103.

Referring now to FIGS. 4A and 4B, as described above, the high temperature resistance of the epoxy modified rigid silicone powder enables the electrosurgical electrode to be heated to temperatures above 500° F. (260° C.) which other non-stick coatings may break down, emit harmful and toxic gaseous byproducts and may micro-fracture during the decomposition. For example, FIGS. 4A to 4B illustrate the results of an experimental comparison between an electrosurgical device coated with polytetrafluoroethylene (PTFE), sold under the trade name DuPont Teflon® 851 204 (the left blade in FIGS. 4A and 4B) and an electrosurgical device coated with an epoxy modified rigid silicone powder (the black colored right blade in FIGS. 4A and 4B) after the two blades are each subjected to a “power” setting of between 5.0 and 9.0 kv and a “Coag” setting between 70 and 150 for a period of between 10 and 30 seconds using a ValleyLab generator, model Force 40S-20. It should be appreciated that the shown blades were not cleaned after a test cutting the same piece of calves liver (which is a common medical industry substitute for human flesh for electrosurgical testing). As seen in these figures, while the black colored epoxy modified rigid silicone powder coated blade substantially retains the epoxy modified rigid silicone powder coating (as seen as the shiny black color in the color photographs submitted to the U.S. Patent and Trademark Office), the PTFE coated blade exhibits substantial decomposition and discoloring of the green color PTFE, wherein the separate bands of discoloration of the green color on portion of the blade show the effect of elevated temperatures on the PTFE coated blade. Accordingly, unlike the PTFE coated blade, except at the tip or edge of the blade, there is substantially no deterioration or discoloration of the epoxy modified rigid silicone powder coating.

As described above, surgeons often utilize a scratch pad to periodically remove the built-up eschar from the used blade by scraping the residue with a scratch pad which resembles medium coarse sandpaper bonded to a layer of resilent foam. In performing this abrasive function, surgeons often sand thru the eschar and start to erode the protective finish on the blade. That is, the surgeon may sand thru the coating which provides the blade with non-stick properties, removing part of or all of the non-stick surface applied to the blade. Accordingly, a comparative abrasion test was performed with laparoscopic blades coated with PTFE DuPont Teflon and laparoscopic blades coated with the epoxy modified rigid silicone powder particles described above to demonstrate the relative weakness when subjected to mechanical abrasion of the PTFE DuPont Teflon coated blade when compared to the rigid epoxy silicone coated blade described above. It should be appreciated that the below-described tests were performed using a rigid epoxy silicone coated blade with the chemical composition of the specific, designated embodiment described above.

The comparative abrasion test included repeatedly withdrawing a laparoscopic blade from between two facing layers of a scratch pad material, wherein a weight was placed on the upper scratch pad. Each scratch pad was constructed of foam between the abrasive on one side and the adhesive on the bottom. Specifically, the test included configuring two face-to-face scratch pads in a sandwich configuration with one abrasive pad facing the other abrasive pad. The bottom pad was held in place with an adhesive on the bottom of the pad and the top pad was held in place directly above the bottom pad by a suitable device. A 500-gram weight was placed on the top pad (to add pressure) and attached to the top of the top scratch pad with an adhesive. The test included separating the two pads, putting a blade in completely to the coated section (before the narrowing of the blade), lowering the weighted top pad and manually withdrawing at a slow speed of approximately one inch per second. This procedure was repeated 50 times with the individual group of blades weighed every ten cycles. Both groups of blades were separate. The test blades had an attached two inch long tape handle to reduce the vertical loading of the manual withdrawal motion.

The test included weighing each coated blade individually with a tenth-milligram (0.0001 gram resolution) scale prior to the testing and every ten cycles of “pulls”. Table 1 of FIG. 15A and Graph 1 of FIG. 15B illustrate the results of a total of 50 test blades, organized into groups of five blades, which were “pull” tested to determine the average weight loss. As illustrated in Table 1, Column A, the average weight loss of the Teflon 851-204 was 0.0021 grams. As seen in FIGS. 5 to 8, such a weight loss resulted in the bare stainless blade showing on 85% of the surface of the 851-204 Teflon®-coated blade (i.e., the green colored blades on the right side of each pair of blades) after the abrasion test. Column B of Table 1 demonstrates the average weight loss of the rigid epoxy silicone material coated blade undergoing the very same “pull” test was 0.0011 grams. As seen in FIGS. 5 to 8, such a weight loss resulted in the bare stainless blade showing on 5% of the surface of the rigid epoxy silicone material coated blade (i.e., the black colored blades on the left side of each pair of blades) after the abrasion test.

As illustrated in Table 1 and Graph 1, the average milligram weight lost at fifty withdrawals through the scratch pad test, when comparing the 851-204 Teflon®-coated blade or the rigid epoxy silicone material coated blade, in all cases, showed essentially double the weight loss of the 851-204 Teflon®-coated blade compared to the rigid epoxy silicone material coated blade. The average milligram weight loss of the rigid epoxy silicone material coated blade was 0.0011 grams or one milligram. The average weight loss of the 851-204 Teflon®-coated blade was 0.0021 milligrams.

Table 2 of FIG. 16A and Graph 2 of FIG. 16B, show the average wear (in inches) of the 851-204 Teflon®-coated blade and the rigid epoxy silicone material coated blade after fifty withdrawals through the scratch pad. These results show that by initially applying a thicker coating of the rigid epoxy silicone material than the 851-204 Teflon® coating, a significantly thicker layer of the rigid epoxy silicone material remains on the blade than the 851-204 Teflon®-coating. It should be appreciated that, as described above, the physical properties of the 851-204 Teflon®-coating prevent a thicker coating to be initially applied, while the rigid epoxy silicone material has no such restrictions. As mentioned above, a thicker coating of the rigid epoxy silicone material may be applied to a blade at substantially the same cost as a thinner coating of the 851-204 Teflon®. Such a thicker coating at substantially the same cost provides another benefit (in addition to the various performance benefits described below) of a rigid epoxy silicone material coated blade when compared to 851-204 Teflon® coated blade.

It should be appreciated that one of the visual observations with the 851-204 Teflon®-coated blade was that, after a series of tests but before the 30th cycle was undertaken, the blade showed the underlayment stainless steel, which is much harder than the 851-204 Teflon®-coating. As seen in FIGS. 5 to 8, this distorted the actual wear of the 851-204 Teflon®-coating as once the coating was worn thru, the weight loss declined. Accordingly, the 851-204 Teflon®-coating was essentially missing from the test surface after 30 pulls, which reduced the apparent weight loss of the 851-204 Teflon®-coating. Thus, the 851-204 Teflon®-coated blade wore much more visibly than the rigid epoxy silicone material coated blade which had a visible and measurable amount of material still protecting the stainless steel blade and maintained non-stick properties due to the coating not being removed.

Moreover, this test does not take into consideration the poor function of the 851-204 Teflon®-coated blade after the test. As described above, the 851-204 Teflon®-coating is absent from the blade surface which results in an unprotected blade when the 851-204 Teflon®-coated blade is used for laparoscopy. On the other hand, since the rigid epoxy silicone coated blade retained more than half of the thickness of the rigid epoxy silicone coating after the fifty pull test, the rigid epoxy silicone coated blade retains the non-stick properties described above.

The relatively unchanged non-stick function of the rigid epoxy silicone coated blade was further demonstrated by a comparative “liver cutting test” (i.e., a simulated medical procedure) which showed the eschar buildup on the 851-204 Teflon®-coated blade after the test and the eschar buildup on the rigid epoxy silicone material coated blade after the test. This test consisted of electronically connecting new blades to a ValleyLab generator (model Force 40S-20) with machine settings of: a “power” setting of 9.0 kv and a “Coag” setting of 150. The new blades are used to cut calves' liver meat to a depth of one half inch (½″) for a distance of one inch (1″). The results of this test, as seen in FIGS. 9 to 12 and as illustrated in Table 3 of FIG. 17, show that 0.005 grams of eschar built up on the 851-204 Teflon®-coated blade (the right-hand side partially green colored blades in FIGS. 9 and 10 and the blades in FIG. 12), while 0.003 grams of eschar built up on the rigid epoxy silicone material coated blade (the left-hand side black colored blades in FIGS. 9 and 10 and the blades in FIG. 11) after each blade was subjected to the exact same abrasion test followed by the exact same “liver cutting test” as is known in the art.

After the cutting test, the blades were manually cleaned as recommended by manufacturers of laparoscopic blades that apply nonstick coatings to blades. To clean each blade while in the pencil, a surgical gauze pad is used to wipe the burned and adhered eschar from the blade surface by pinching the blade between the thumb and forefinger with the gauze between the thumb and forefinger on both sides of the cutting blade. The blades are then withdrawn five times from the pinched position, thus replicating approximately 10 seconds worth of time of cleaning the blade manually.

The results of this cleaning, as seen in FIGS. 13 and 14 and as illustrated in Table 3, show that even after being wiped down with a surgical gauze pad, 0.003 grams of eschar built up on the 851-204 Teflon®-coated blade (the blades in FIG. 14), while only 0.001 grams of eschar built up on the rigid epoxy silicone material coated blade (the blades in FIG. 13) after each blade was subjected to the exact same “liver cutting test” and then manually wiped clean with a surgical gauze pad.

Accordingly, it can be concluded that rigid epoxy silicone-coated blades exhibited better nonstick characteristics in three critical areas. Based on the initially adhered eschar, removed eschar, and retained eschar after the cleaning procedure, as measured by increase in weight to the total weight of the five-blade sample, the rigid epoxy silicone-coated blade showed superior nonstick characteristics. The comparison of 0.003 grams of the eschar buildup, prior to cleaning of the rigid epoxy silicone-coated blade, versus 0.005 grams of the 851-204 Teflon®-coated blade shows a 66% improvement in the basic nonstick characteristics of the eschar not adhering or accumulating on the rigid epoxy silicone-coated blade.

Moreover, after cleaning with a surgical gauze pad, the amount of eschar remaining on the blade's surface indicates that the rigid epoxy silicone coated-blade was less contaminated because less eschar, by weight, was accumulated on the average of the five-blade sample. The retained eschar was 50% less with the rigid epoxy silicone coated blade. The ease of cleaning shows that both types of coated blades did release the eschar that was accumulated after the initial tests. However, it appears that the rigid epoxy silicone coated blade accumulated less initial eschar and, therefore, less eschar could be potentially removed through the gauze wipe test. The nonstick characteristics provided by either nonstick coating showed the percentage of eschar removed by the wiping test was greater with the rigid epoxy silicone coated-blade.

Furthermore, the total retained weight of the eschar accumulating on the surface (which contaminates the blade prior to the next surgical procedure using the blade) showed an improvement by the rigid epoxy silicone-coated blade versus the PTFE-coated Teflon® 851-204 blade. That is, an amount of eschar weight retained by the Teflon® 851-204 blade (0.002 grams) was twice as much versus the eschar weight retained by the rigid epoxy silicone blade (0.001 grams). This fifty percent reduction in the amount accumulated eschar, in favor of the rigid epoxy silicone coated blade, correlates to improved surgical procedures by providing a user with a cleaner blade with well-defined, cleaner cutting and better coagulation properties. That is, the Teflon® 851-204 coated blades showed extensive adherence of eschar requiring extensive abrasive pad scraping to remove the adhered eschar, which would extend the surgical procedure due to the adhered eschar or requiring a new blade to be fitted. The eschar buildup on blades causes increased electrical resistance, which requires increasing the current settings during the surgical procedure and also increases the risk of misdirected current. The cleaning of the blades during a procedure adds time and causes interruptions in the procedure. Without continual cleaning of the eschar, the blade provides a less precise surgical incision.

In one embodiment, in addition to the epoxy modified rigid silicone powder particles, a plurality of anti-microbial particles such as silver or silver compounds are applied to one or more of the surfaces of the electrosurgical device to reduce and kill bacteria and other potential germs that may be located on the surface(s) of the electrosurgical device. In one aspect of this embodiment, the anti-microbial particles are interspersed with the epoxy modified rigid silicone powder particles and a layer of anti-microbial material is applied to the electrosurgical device along with the epoxy modified rigid silicone powder particles. The above process can be repeated as necessary to maintain the effectiveness of the anti-microbial surface. The addition of the anti-microbial material tends to kill bacteria or other harmful organisms that contact the surface of the electrode during and after the surgical procedure. This coated electrode can be used multiple times in different surgical procedures without requiring sterilization (even though sterilization is preferred) because the anti-microbial particles kill the bacteria and other harmful organisms which contact the surfaces of the electrode. The coated electrosurgical device therefore minimizes the chance of infections or other complications in the body after the surgical procedure is complete.

In another embodiment, one or more additional epoxy modified rigid silicone powder layers are applied to the first or primary epoxy modified rigid silicone powder layer applied to the surface of the electrosurgical device to meet specific design specifications or coating requirements of a manufacturer. In this embodiment, the epoxy modified rigid silicone powder may be applied selectively to the electrosurgical device. For example, the epoxy modified rigid silicone powder may be applied to a long shank of a very long electrosurgical blade wherein the round shank is coated with two or more layers of the epoxy modified rigid silicone powder to create a thicker coating than a blade portion which is coated with one coat. In different embodiments, the additional bonding material layers may be the same or different than the first epoxy modified rigid silicone powder layer and are applied to the first epoxy modified rigid silicone powder layer until a predetermined thickness is achieved. Additionally, different materials may be added to the bonding material layer or layers, based on specific design specifications.

It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.

Claims

1. A method of coating a medical device, the method comprising: applying a non-stick coating to a first portion of a surface of a conductive substrate of the medical device, wherein the non-stick coating includes a plurality of epoxy modified rigid silicone particles each having a size of no greater than one-hundred-fifty microns, and wherein the non-stick coating retains nonstick properties after being heated to up to 850° F.; andat least partially curing the applied non-stick coating.

2. The method of claim 1, wherein the epoxy modified rigid silicone particles at least include: (a) a solvent-free hydroxyl functional solid phenyl silicone resin;(b) a calcium metasilicate;(c) an epoxy cresol novalac resin;(d) a 60% active powder version of a methyl alkyl polysiloxane;(e) an o-cresol novolac resin; and(f) an acrylate copolymer.

3. The method of claim 2, wherein: (a) the solvent-free hydroxyl functional solid phenyl silicone resin is in the range of about 40% to about 60% parts per weight of the coating;(b) the calcium metasilicate is in the range of about 20% to about 40% parts per weight of the coating;(c) the epoxy cresol novalac resin is in the range of about 5% to about 15% parts per weight of the coating;(d) the 60% active powder version of a methyl alkyl polysiloxane is in the range of about 3% to about 7% parts per weight of the coating;(e) the o-cresol novolac resin is in the range of about 0.5% to about 3% parts per weight of the coating; and(f) the acrylate copolymer is in the range of about 0.5% to about 3% parts per weight of the coating.

4. The method of claim 1, wherein the conductive substrate comprises a metal.

5. The method of claim 1, wherein a plurality of anti-microbial particles are interspersed in said non-stick coating.

6. The method of claim 5, wherein the anti-microbial particles comprise particles selected from the group consisting of: silver particles and ceramic particles.

7. The method of claim 1, wherein a plurality of electrically conductive particles are interspersed in said non-stick coating.

8. The method of claim 1, wherein at least part of the conductive substrate forms a shape selected from the group consisting of: a blade, a knife, a wire, a needle, a probe and a ball.

9. The method of claim 1, wherein the medical device comprises an electrosurgical electrode.

10. A method of coating a medical device, the method comprising: applying a coating to a first portion of a surface of a substrate of the medical device, wherein: the coating includes a plurality of particles each having a size of no greater than one-hundred-fifty microns, andthe coating includes: a solvent-free hydroxyl functional solid phenyl silicone resin;a calcium metasilicate;an epoxy cresol novalac resin;a 60% active powder version of a methyl alkyl polysiloxane;an o-cresol novolac resin; andan acrylate copolymer; andat least partially curing the applied coating.

11. The method of claim 10, wherein: (a) the solvent-free hydroxyl functional solid phenyl silicone resin is in the range of about 40% to about 60% parts per weight of the coating;(b) the calcium metasilicate is in the range of about 20% to about 40% parts per weight of the coating;(c) the epoxy cresol novalac resin is in the range of about 5% to about 15% parts per weight of the coating;(d) the 60% active powder version of a methyl alkyl polysiloxane is in the range of about 3% to about 7% parts per weight of the coating;(e) the o-cresol novolac resin is in the range of about 0.5% to about 3% parts per weight of the coating; and(f) the acrylate copolymer is in the range of about 0.5% to about 3% parts per weight of the coating.

12. The method of claim 10, wherein the substrate comprises a metal.

13. The method of claim 10, wherein a plurality of anti-microbial particles are interspersed in said coating.

14. The method of claim 13, wherein the anti-microbial particles comprise particles selected from the group consisting of: silver particles and ceramic particles.

15. The method of claim 10, wherein a plurality of electrically conductive particles are interspersed in said coating.

16. The method of claim 10, further comprising applying a top coat to the at least partially cured coating.

17. The method of claim 16, wherein the top coat is selected from the group consisting of: an abrasive resistant coating, a non-stick coating, an anti- microbial coating and an electrically conductive coating.

18. The method of claim 10, wherein at least part of the substrate forms a shape selected from the group consisting of: a blade, a knife, a wire, a needle, a probe and a ball.