Method for manufacturing an end effector assembly

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application Ser. No. 60/722,186 by Paul Guerra entitled “METHOD FOR MANUFACTURING AN END EFFECTOR ASSEMBLY” filed on Sep. 30, 2005, the entire contents of which is incorporated herein by reference.

[0002] The present disclosure relates to electrosurgical instruments used for open and endoscopic surgical procedures. More particularly, the present disclosure relates to a method of manufacturing a bipolar forceps for sealing vessels and vascular tissue having an electrode assembly that is designed to enhance electrical isolation of the surface of the jaw of the forceps from an underlying strength member.

[0003] A hemostat or forceps is a simple plier-like tool that uses mechanical action between its jaws to constrict tissue and is commonly used in open surgical procedures to grasp, dissect and/or clamp tissue. Electrosurgical forceps utilize both mechanical clamping action and electrical energy to effect hemostasis by heating the tissue and blood vessels to coagulate, cauterize and/or seal tissue.

[0004] By utilizing an electrosurgical forceps, a surgeon can either cauterize, coagulate/desiccate tissue and/or simply reduce or slow bleeding by controlling the intensity, frequency and duration of the electrosurgical energy applied to the tissue. Generally, the electrical configuration of electrosurgical forceps can be categorized in two classifications: 1) monopolar electrosurgical forceps; and 2) bipolar electrosurgical forceps.

[0005] Monopolar forceps utilize one active electrode associated with the clamping end effector and a remote patient return electrode or pad that is attached externally to the patient. When the electrosurgical energy is applied, the energy travels from the active electrode, to the surgical site, through the patient and to the return electrode.

[0006] Bipolar electrosurgical forceps utilize two generally opposing electrodes that are generally disposed on the inner facing or opposing surfaces of the end effectors, which are, in turn, electrically coupled to an electrosurgical generator. Each electrode is charged to a different electric potential. Since tissue is a conductor of electrical energy, when the end effectors are utilized to clamp or grasp tissue therebetween, the electrical energy can be selectively transferred through the tissue.

[0007] Over the last several decades, more and more surgeons are complimenting traditional open methods of gaining access to vital organs and body cavities with endoscopes and endoscopic instruments that access organs through small puncture-like incisions. Endoscopic instruments are inserted into the patient through a cannula, or port, that has been made with a trocar. Typical sizes for cannulas range from three millimeters to twelve millimeters. Smaller cannulas are usually preferred, which, as can be appreciated, ultimately presents a design challenge to instrument manufacturers who must find ways to make surgical instruments that fit through the cannulas.

[0008] Certain surgical procedures require sealing blood vessels or vascular tissue. However, due to space limitations, surgeons can have difficulty suturing vessels or performing other traditional methods of controlling bleeding, e.g., clamping and/or tying-off transected blood vessels. Blood vessels, in the range below two millimeters in diameter, can often be closed using standard electrosurgical techniques. If a larger vessel is severed, it may be necessary for the surgeon to convert the endoscopic procedure into an open-surgical procedure and thereby abandon the benefits of laparoscopy.

[0009] It is known that the process of coagulating small vessels is fundamentally different than vessel sealing. For the purposes herein the term “coagulation” is defined as a process of desiccating tissue wherein the tissue cells are ruptured and dried. The term “vessel sealing” is defined as the process of liquefying the collagen in the tissue so that the tissue cross-links and reforms into a fused mass. Thus, coagulation of small vessels is sufficient to close them, however, larger vessels need to be sealed to assure permanent closure.

[0010] Several journal articles have disclosed methods for sealing small blood vessels using electrosurgery. An article entitled Studies on Coagulation and the Development of an Automatic Computerized Bipolar Coagulator, Journal of Neurosurgery, Volume 75, July 1991, describes a bipolar coagulator that is used to seal small blood vessels. The article states that it is not possible to safely coagulate arteries with a diameter larger than 2 to 2.5 mm. A second article is entitled Automatically Controlled Bipolar Electrocoagulation—“COA-COMP”, Neurosurg. Rev. (1984), pp. 187-190, describes a method for terminating electrosurgical power to the vessel so that charring of the vessel walls can be avoided.

[0011] In order to effect a proper seal with larger vessels, two predominant mechanical parameters must be accurately controlled—the pressure applied to the vessel and the gap between the electrodes, both of which affect thickness of the sealed vessel. More particularly, accurate application of the pressure may be important for several reasons: 1) to oppose the walls of the vessel; 2) to reduce the tissue impedance to a low enough value that allows enough electrosurgical energy through the tissue; 3) to overcome the forces of expansion during tissue heating; and 4) to contribute to the end tissue thickness, which is an indication of a good seal. In some instances a fused vessel wall is optimum between 0.001 and 0.006 inches. Below this range, the seal may shred or tear and above this range the lumens may not be properly or effectively sealed.

[0012] Numerous bipolar electrosurgical instruments have been proposed in the past for various open and endoscopic surgical procedures. However, some of these designs may not provide uniformly reproducible pressure to the blood vessel and may result in an ineffective or non-uniform seal. For example, U.S. Pat. No. 2,176,479 to Willis, U.S. Pat. Nos. 4,005,714 and 4,031,898 to Hiltebrandt, U.S. Pat. Nos. 5,827,274, 5,290,287 and 5,312,433 to Boebel et al., U.S. Pat. Nos. 4,370,980, 4,552,143, 5,026,370 and 5,116,332 to Lottick, U.S. Pat. No. 5,443,463 to Stern et al., U.S. Pat. No. 5,484,436 to Eggers et al. and U.S. Pat. No. 5,951,549 to Richardson et al., all relate to electrosurgical instruments for coagulating, sealing and cutting vessels or tissue.

[0013] Many of these instruments include blade members or shearing members that simply cut tissue in a mechanical and/or electromechanical manner and are relatively ineffective for vessel sealing purposes. Other instruments generally rely on clamping pressure alone to procure proper sealing thickness and are often not designed to take into account gap tolerances and/or parallelism and flatness requirements, which are parameters that, if properly controlled, can assure a consistent and effective tissue seal. For example, it is difficult to adequately control thickness of the resulting sealed tissue by controlling clamping pressure alone for either of two reasons: 1) if too much force is applied, there is a possibility that the two poles will touch and energy will not be transferred through the tissue resulting in an ineffective seal; or 2) if too low a force is applied, a thicker less reliable seal is created.

[0014] Currently, several tissue sealing devices employ jaws that are designed as two separate parts. The jaw is first covered in an over-mold material. Then the seal plate and the covered jaw are over-molded together. As a result, this manufacturing process requires two mold tools. In addition, each part must include features by which the part can be held while the molding occurs.

[0015] It is an object of the present disclosure to provide a method for manufacturing an open and/or endoscopic electrosurgical instrument in which the two separate parts of the jaws of the forceps can be molded simultaneously to save tooling costs by first disposing an insulating layer on the back of the seal plate.

[0016] It is another object of the present disclosure to provide an open and/or endoscopic electrosurgical instrument in which the covering or coating on the back of the seal plate has enhanced thermal and electrical properties for isolation as compared to the thermal and electrical properties of the plastic mold material.

[0017] More particularly, one embodiment of the present disclosure relates to a method of manufacturing a jaw member of an end effector assembly for use with an electrosurgical instrument. The method includes the steps of providing an electrically conductive tissue engaging plate and a jaw support; covering one side of the electrically conductive tissue engaging plate with an electrically insulative, thermally non-degrading coating; placing and securing the electrically conductive tissue engaging plate and the jaw support into a jaw mold; and introducing a liquid substance into the jaw mold and allowing the liquid substance to cure around the electrically conductive tissue engaging plate and the jaw support. The coating of the covering step may be of uniform thickness across the electrically conductive tissue engaging plate. In addition, the coating of the covering step may include a thickness which provides a gap-set between the electrically conductive tissue engaging plate and the jaw support during the introducing step.

[0018] One embodiment of the present disclosure relates to another method for manufacturing a jaw member of an end effector assembly for use with an electrosurgical instrument wherein the method includes the steps of: providing an electrically conductive tissue engaging plate and a jaw support; covering one side of the electrically conductive tissue engaging plate with an electrically insulative, thermally non-degrading coating; and securing the side of the electrically conductive tissue engaging plate onto the jaw support with an adhesive. The coating of the covering step may be of uniform thickness across the electrically conductive tissue engaging plate. The coating of the covering step may include a thickness which provides a gap-set between the electrically conductive tissue engaging plate and the jaw support during the introducing step.

[0028] It has been found that by altering the configuration of the electrode insulating material relative to the electrically conductive sealing surface, surgeons can more readily and easily produce a consistent, high quality seal and effectively reduce thermal spread across or to adjacent tissue. For the purposes herein the term “thermal spread” refers generally to the heat transfer (heat conduction, heat convection or electrical current dissipation) dissipating along the periphery of the electrically conductive or electrically active surfaces to adjacent tissue. This can also be termed “collateral damage” to adjacent tissue. It is envisioned that the configuration of the insulating material that surrounds the perimeter of the electrically conductive surface will effectively reduce current and thermal dissipation to adjacent tissue areas and generally restrict current travel to areas between the opposing electrodes. As mentioned above, this is different from dielectrically coating the outer surfaces of the instrument to prevent tissue “blanching” at points normal to the sealing site. These coatings are not designed or intended to reduce collateral tissue damage or thermal spread to adjacent tissue (tissue lying along the tissue sealing plane).

[0029] More particularly, altering the geometrical dimensions of the insulator relative to the electrically conductive surface alters the electrical path, thereby influencing the thermal spread/collateral damage to adjacent tissue structures. Preferably, the geometry of the insulating substrate also isolates the two electrically opposing poles (i.e., electrodes) from one another, thereby reducing the possibility that tissue or tissue fluids can create an unintended bridge or path for current travel. In other words, the insulator and electrically conductive sealing surface are preferably dimensioned such that the current is concentrated at the intended sealing site between the opposing electrically conductive surfaces as explained in more detail below.

[0030] Referring now to FIG. 1, an electrode jaw member 110 of an end effector assembly of the prior art is shown in which an electrically conductive seal surface 112 is disposed on an electrically insulating layer 111. The electrically conductive seal surface 112 contacts tissue. The electrically conductive seal surface 112 has a width such that the electrically conductive seal surface 112 overlaps the electrically insulating layer 111. The joining process of the electrically conductive seal surface 112 and the electrically insulating layer 111 result in electrode jaw member 110 having a height “h1”.

[0031] With respect to the method of manufacturing electrode jaw member 110, the jaw member 110 is first covered in an over-mold material and then the seal plate 112 and covered jaw 112 are over-molded together. The process requires two mold tools and features on each part to be held while the molding occurs.

[0032] Referring to FIGS. 2A, 2B, 3A and 3B, in one embodiment of the present disclosure, as best shown in FIG. 2A, a jaw member 310 of an electrosurgical forceps may include a support base 319 which extends distally from a flange 313. The jaw member 310 includes an electrically conductive tissue engaging surface or sealing plate 312. As best shown in FIG. 2B, the electrically conductive tissue engaging sealing plate 312 has vertically-extending edges 332, 334 extending about a periphery and along a length thereof of the electrically conductive plate 312. Vertically-extending edges 332 extend externally along the electrically conductive tissue engaging surface or sealing plate 312 while vertically-extending edges 334 extend internally along an opposite side surface 312′ of the electrically conductive tissue engaging surface or sealing plate 312. An electrically insulating layer 211 is disposed on the opposite side surface 312′ and along the vertically-extending edges 334 that extend internally along the opposite side surface 312′ and along at least a portion of the vertically-extending edges 332 that extend externally along the electrically conductive tissue engaging surface or sealing plate 312. A jaw support base 319 together with the electrically insulating layer 211 and electrically conductive tissue engaging surface 312 are encapsulated by an outer insulative housing or overmolding 314. Overmolding 314 includes a cavity 314a is dimensioned to securely engage the electrically conductive sealing surface or sealing plate 312 as well as the support base 319 and electrically insulating layer 211. Consequently, jaw member 310 has an electrically conductive sealing surface or sealing plate member 312 that is substantially surrounded by electrically insulating layer 211 and outer insulative housing or overmolding 314. The electrically conductive seal surface 312 contacts tissue.

[0033] For example, and as shown in FIG. 2A, the electrically conductive sealing plate 312 includes a peripheral flange 313, which surrounds the periphery of the sealing plate 312.

[0034] Flange 313, is designed to matingly engage an inner lip 317 of the outer insulative housing or overmolding 314. A lead 325a extending from a circuit board (not shown) terminates within the outer insulating housing or overmolding 314 and is designed to electro-mechanically couple to the sealing plate 312 by virtue of a crimp-like connection 326a. For example, the electrically insulating layer 211 is disposed on the opposite side surface 312′ and along the vertically-extending edges 334 that extend internally along the opposite side surface 312′ and along at least a portion of the vertically-extending edges 332 that extend externally along the electrically conductive tissue engaging surface or sealing plate 312, electrically conductive sealing surface 312 and the outer insulating housing or overmolding 314 are preferably dimensioned to limit and/or reduce many of the known undesirable effects related to tissue sealing, e.g., flashover, thermal spread and stray current dissipation

[0035] As best shown in FIG. 4, electrically conductive sealing surface 312 may also include outer peripheral edges 332′ that have a pre-defined radius and the outer insulating housing or overmolding 314 meets the electrically insulating layer 211 and the electrically conductive sealing surface 312 along an adjoining edge 332 of the sealing surface 312 in a generally tangential position. At the interface, the electrically conductive surface 312 is raised relative to the outer housing 314.

[0036] As best illustrated in FIGS. 3A and 3B, jaw member 320 includes similar elements to jaw member 310 such as jaw insulating housing or overmolding 324, that encapsulates a support plate 329, an electrically insulating layer 221 and an electrically conductive tissue engaging sealing surface or sealing plate member 322. Similarly, the electrically conductive tissue engaging sealing plate 322 has vertically-extending edges 342, 344 extending about the periphery and along a length thereof of the electrically conductive plate 322. Vertically-extending edges 342 extend externally along the electrically conductive tissue engaging surface or sealing plate 322 while vertically-extending edges 344 extend internally along an opposite side surface 322′ of the electrically conductive tissue engaging surface or sealing plate 322. The electrically conductive surface or sealing plate member 322 forms a channel 362 on the opposite side surface 322′ of electrically conductive surface or sealing plate 322 such that the electrically conductive surface or sealing plate 322 and the channel 362 are dimensioned for the channel 362 to receive electrically insulating layer 221 disposed on the opposite side surface 322′.

[0037] Jaw member 320 may be assembled in a similar manner as described above with respect to jaw member 310, as described below.

[0038] Jaw members 310 and 320 are electrically isolated from one another such that electrosurgical energy can be effectively transferred through the tissue to form a tissue seal. For example, each jaw member, e.g., 310, includes a uniquely-designed electrosurgical cable path disposed therethrough that transmits electrosurgical energy to the electrically conductive sealing surface 312. Cable leads 325a and 325b, which supply power to electrode jaw members 310 and 320, respectively, are coupled to an electrosurgical generator (not shown) and are supported via support plates 319 and 329, respectively, and are held loosely but securely along the cable path to permit rotation of the jaw members 310 and 320. This configuration isolates electrically conductive sealing surface 312 from the remaining operative components of the end effector assembly 1000 or 122, jaw member 320 and shaft 12 or 109 (see FIGS. 6 and 7) and conversely isolates electrically conductive sealing surface 322 from the remaining operative components of the jaw member 310. The two electrical potentials are isolated from one another by virtue of the insulative sheathing surrounding the cable leads 325a and 325b.

[0039] FIG. 4 shows, in one embodiment, that the electrically insulating layer 211 or 221 may be made from a polymer or a polymer solution, which can be sprayed onto the opposite sides 312′ and 322′ of the conductive sealing surface 312 and 322, respectively. Alternatively, a ceramic material may be applied to the opposite sides 312′ and 322′ of electrically conductive seal plates or sealing surfaces 312 and 322 by plasma deposition or by other suitable mechanical techniques. The electrically insulating layers 211 and 221 may also be sprayed on in a uniform thickness to assure flatness.

[0040] By applying a coating of electrically insulating layer 211 and 221 onto sides 312′ and 322′ and vertically extending edges 332, 334 and 342, 344 of electrically conductive seal plates 312 and 322, respectively, enhanced thermal and electrical properties are provided so as to increase electrical and thermal isolation during activation, and may be dimensioned to regulate the gap distance to within a preferred gap range as described in more detail below with respect to FIG. 6. The coating of electrically insulating layer 211 and 221 may be made from a material selected from the group consisting of flame sprayed ceramic, vapor deposition polymer (parylene), an oxide layer, and an anodized coating.

[0041] In one particularly useful embodiment, overmoldings 314 and 324 are made from molded plastic material.

[0042] In another particularly useful embodiment, as best illustrated in FIGS. 2, 3 and 5, the insulating layer 211 of electrode 310 is attached to seal surface 312′ by applying an adhesive in an adhesive layer 251. The adhesive layer 251 may include a material that includes polyurethane or other adhesive fluids. In this case, the application of the jaw overmolding 314 is applied over the insulating layer 211 is optional. Those skilled in the art will recognize that adhesive 251 may be applied in a similar manner to the insulating layer 221 of electrode 320 and seal surface 322′. The method of manufacturing the insulating layer 211 or 221 using adhesive 251 is described below.

[0043] As mentioned above, the electrically insulating layers 211 and 221 and the overmolding 314 and 324 not only insulate the electric current but may also be dimensioned to regulate the gap distance G between the electrodes 310 and 320 when closed about tissue, which is known to contribute to the seal quality, consistency and the reduction of thermal spread across the tissue (See FIG. 6). Specifically, the coating regulates the gap set between the jaw support 319 or 329 and the plate 312 or 322 when inserted into the mold, The jaw mechanism (i.e., jaw members 310 and 320) and the coated seal surfaces 312 and 322 are held together simultaneously in a mold tool while plastic is caused to flow around the jaw members 310 and 320.

[0044] In addition, by attaching the electrically insulating layer 211 and 221 and overmolding 314 and 324 to the conductive surfaces 312′ and 322′, respectively, utilizing one of the above assembly techniques, the alignment and thickness, i.e., height “h2”, of the electrodes 310 and 320 can be controlled. For example, and as best illustrated in comparison of FIG. 1 to FIG. 4, the overmolding manufacturing technique reduces the overall height “h2” (FIG. 4) of the electrode 310 compared to traditional manufacturing techniques, which yield a height of “h1” (FIG. 1). The smaller height “h2” allows a user access to smaller areas within the body and facilitates sealing around more delicate tissue areas.

[0045] Moreover, the overmolding technique provides more insulation, i.e., electrically Insulative layers 211 and 221, along the vertically extending edges of the electrically conductive surface, which also reduces thermal spread due to less electrode to tissue contact. By dimensioning electrically insulating layer, e.g., 211 and electrode 310 in this fashion (i.e., with reduced conductive surface area), the current is restricted (i.e., concentrated) to the intended seal area rather than current being able to travel to tissue outside the seal area, which may come into contact with an outer edge of the electrode 310 (see FIG. 4). In addition, the material of the jaw overmolding 314 (and 324) provides enhanced thermal and electrical insulation properties during activation.

[0046] More particularly, the varying geometry of the electrically insulating layer 211 (and 221) and jaw overmolding 314 (and 324) compared to the electrically conductive surface 312 also isolates the two opposing poles during activation, thereby reducing the possibility that tissue or tissue fluids will bridge a path for stray current being able to travel to surrounding tissue. As best seen in FIGS. 3A, 3B, 4 and 5, the electrode 310 may also include a pinch trim 331 that facilitates secure, integral engagement of the electrically insulating layer 211 (and 221) and jaw overmolding 314 (and 324) and the electrically conductive sealing surface 312 during the assembly and/or manufacturing process.

[0047] FIG. 6 shows a bipolar forceps 10 having an end effector assembly 1000 during use wherein handle members 16 and 18 are moved closer to one another to apply clamping force to the tubular tissue 150 to effect a seal 152. The end effector assembly 1000 may include first and second electrode jaw members 310 and 320, as previously described. Movement of the handle members 16 and 18 closer to one another is restricted by a gap set “G”, which is established between the upper electrically conductive seal plate 312 and the lower electrically conductive seal plate 322 by the application of the electrically insulating seal layers 211 and 221, respectively. Once sealed, the tubular vessel 150 can be cut along seal 152 to separate the tissue 150 and form a gap in the tissue 150 therebetween.

[0048] It is envisioned that by making the electrode assembly 21 disposable, the electrode assembly 21 is less likely to become damaged since it is only intended for a single operation and, therefore, does not require cleaning or sterilization. As a result, the functionality and consistency of the sealing components, e.g., the electrically conductive surface 312 (and 322) and electrically insulating layer 211 (and 221) and jaw overmolding 314 (and 324) will assure a uniform and quality seal and provide a tolerable and reliable reduction of thermal spread across tissue. Alternatively, the entire electrosurgical instrument may be disposable, which, again, will assure a uniform and quality seal with minimal thermal spread.

[0049] FIG. 7 shows an endoscopic bipolar instrument 100 during use wherein movement of a handle assembly 128 applies clamping force on the tubular tissue 150 to effect a seal 152. As shown, a shaft 109 and an end effector assembly or electrode assembly 122 are inserted through a trocar 130 and cannula 132 and a handle assembly 118 is actuated to cause opposing jaw members of the electrode assembly 122 to grasp tubular vessel 150 therebetween. More particularly, a movable handle 118b is moved progressively towards a fixed handle 118a, which, in turn, causes relative movement of the jaw members from an open, spaced-apart position to a closed, sealing position. A rotating member 123 allows the user to rotate the electrode assembly 122 into position about the tubular tissue 150 prior to activation. End effector assembly 122 may include first and second electrode jaw members 310 and 320, respectively, as described previously.

[0050] After the jaw members 310 and 320 are closed about the tissue 150, the user then applies electrosurgical energy via connection 128 to the tissue 150. By controlling the intensity, frequency and duration of the electrosurgical energy applied to the tissue 150, the user can either cauterize, coagulate/desiccate seal and/or simply reduce or slow bleeding with minimal collateral or thermal damage to surrounding tissue.

[0051] An electrosurgical forceps such as, for example but not limited to, open bipolar instrument 10 and end effector assembly 1000 (see FIG. 6) and endoscopic bipolar instrument 100 and electrode assembly 122 (see FIG. 7), may include a knife channel for passage of a knife for cutting tissue during surgical procedures.

[0052] From the foregoing and with reference to the various figure drawings, those skilled in the art will appreciate that certain modifications can also be made to the present disclosure without departing from the scope of the present disclosure. For example, although it is preferable that electrodes 310 and 320 meet in parallel opposition and, therefore, meet on the same plane, in some cases it may be preferable to slightly bias the electrodes 310 and 320 to meet each other at a distal end such that additional closure force on the handles 16 and 18 is required to deflect the electrodes in the same plane. It is envisioned that this could improve seal quality and/or consistency.

[0053] Although it is preferable that the electrode assembly 21 include housing 71 and cover plate 80 to engage mechanical forceps 20 therebetween, in some cases it may be preferable to manufacture the electrode assembly 21 such that only one piece, e.g., housing 71 is required to engage mechanical forceps 20.

[0054] The outer surface of the end effectors may include a nickel-based material, coating, stamping, metal injection molding that is designed to reduce adhesion between the end effectors (or components thereof) with the surrounding tissue during or after sealing.

[0055] One embodiment of the foregoing method for manufacturing the jaw member 310 or 320 of an end effector assembly 1000 or 122 for use with an electrosurgical instrument 10 or 100, respectively, includes the steps of providing an electrically conductive tissue engaging plate 312 or 322 and a jaw support 319 or 329 (See FIGS. 2A and 3A); covering one side 312′ or 322′ of the electrically conductive tissue engaging plate 312 or 322 with an electrically insulative, thermally non-degrading coating 211 or 221; placing and securing the electrically conductive tissue engaging plate 312 or 322 and the jaw support 319 or 329 into a jaw mold (not shown) and introducing a liquid substance (not shown) into the jaw mold and allowing the liquid substance (not shown) to cure around the electrically conductive tissue engaging plate 312 or 322 and the jaw support 319 or 329. The liquid substance may be selected from the group consisting of liquid crystal polymer, thermoplastic polymer, epoxy and silicone. The coating 211 or 221 of the covering step may be of uniform thickness across the electrically conductive tissue engaging plate 312 or 322. In addition, the coating 211 or 221 of the covering step may include a thickness that provides the gap-set “G” between the electrically conductive tissue engaging plate 312 or 322 and the jaw support 319 or 329 during the introducing step (see FIG. 6).

[0056] In another particularly useful embodiment, as best illustrated in FIGS. 2A and 3A, the insulating layer 211 and 221 of electrode 310 and 320 is attached to opposite side seal surface 312′ and 322′ via application of adhesive 251. As discussed previously, the adhesive 251 may include a material that includes polyurethane or other materials. Again, in this case, the application of the jaw overmolding 314 and 324 over the insulating layer 211 and 221, respectively, is optional. Those skilled in the art will recognize that adhesive 251 may be applied in a similar manner to the insulating layer 221 of electrode 320 and seal surface 322.

[0057] Again, by applying a coating of electrically insulating layer 211 and 221 onto one side 312′ and 322′ of electrically conductive seal plates 312 and 322, respectively, enhanced thermal and electrical properties are provided so as to increase electrical and thermal isolation during activation and may be dimensioned to regulate the gap distance “G” to within a preferred gap range as described in more detail previously with respect to FIG. 6.

[0058] More particularly, referring to FIG. 6, one embodiment relating to the foregoing method for manufacturing the jaw member 110 or 120 of the end effector assembly 1000 for use with the electrosurgical instrument 10 or 100. The method includes the steps of: providing the electrically conductive tissue engaging plate 312 or 322 and the jaw support 319 or 329; covering one side 312′ or 322′ of the electrically conductive tissue engaging plate 312 or 322 with the electrically insulative, thermally non-degrading coating 211 or 221; and securing the side 312′ or 322′ of the electrically conductive tissue engaging plate 312 or 322 onto the jaw support 319 or 329 with the adhesive 251. The coating 211 or 221 of the covering step may be of uniform thickness across the electrically conductive tissue engaging plate 312 or 322. The coating 211 or 221 of the covering step may include a thickness that provides the gap-set “G” between the electrically conductive tissue engaging plate 312 or 322 and the jaw support 319 or 329 during the introducing step (see FIG. 6).

[0059] While more than one embodiment of the disclosure has been described, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of a preferred embodiment. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.