Patent Description:
A surgical forceps is a pliers-like instrument that relies on mechanical action between its jaw members to grasp, clamp, and constrict tissue. Electrosurgical forceps utilize both mechanical clamping action and energy to heat tissue to treat, e.g., coagulate, cauterize, or seal, tissue. Typically, once tissue is treated, the surgeon has to accurately sever the treated tissue. Accordingly, many electrosurgical forceps are designed to incorporate a knife that is advanced between the jaw members to cut the treated tissue. As an alternative to a mechanical knife, an energy-based tissue cutting element may be provided to cut the treated tissue using energy, e.g., thermal, electrosurgical, ultrasonic, light, or other suitable energy.

<CIT> describes bipolar electrosurgical instruments for cutting, desiccating and sealing tissue. The instrument may be a forceps having first and second jaws. Cutting is achieved by bipolar RF heating between a cutting wire extending along one jaw and a curved electrode on the opposite jaw.

<CIT> describes surgical instruments for tissue sealing and/or cutting. The instrument may include a thermally active surface or element comprising a conductor covered with a ferromagnetic material.

<CIT> describes electrosurgical devices having an electrode including a heater, a heating power supply, and a therapy power supply. The heating power supply provides power to the heater. The therapy power supply provides therapeutic power to the electrode.

<CIT> describes thermal surgical tools having a conductor coated with a ferromagnetic material.

<CIT> describes electrosurgical instruments including an impedance matching circuit to match the load of a thermal element with the impedance of the electrical power source.

<CIT> describes electrosurgical instruments for cutting, desiccating and sealing tissue. The instrument may be a forceps having first and second jaws. A electrically heated cutting wire may extend along one of the jaws.

As used herein, the term "distal" refers to the portion that is being described which is further from a user, while the term "proximal" refers to the portion that is being described which is closer to a user. Further, to the extent consistent, any or all of the aspects detailed herein may be used in conjunction with any or all of the other aspects detailed herein.

The present disclosure provides an electrosurgical instrument as defined in claim <NUM>.

Optionally, the first portion defines a first Curie temperature and the second portion defines a second Curie temperature different from the first Curie temperature. Alternatively, the Curie temperatures of the first and second portions may be the same.

Optionally, the ferromagnetic coating of the first portion is different from the ferromagnetic coating of the second portion, e.g., different in thickness, surface roughness, and/or material. Alternatively, the coatings may be the same.

Optionally, the first jaw member includes an electrically-conductive plate defining at least a portion of the first opposed surface.

Optionally, the first portion of the thermal cutting wire extends at least partially within a depression defined within the electrically-conductive plate.

In other embodiments, the first portion of the thermal cutting wire extends at least partially within a channel defined between spaced-apart portions of the electrically-conductive plate.

Optionally, the thermal cutting wire includes a conductive core. In such embodiments, the ferromagnetic coating is disposed about the conductive core.

Optionally, the thermal cutting wire defines a Curie temperature of between <NUM> and <NUM>. Other temperature or temperature ranges are also contemplated.

In embodiments, the thermal cutting wire includes a conductive core, a ferromagnetic coating disposed about the conductive core, and a thermally-conductive, electrically-insulative material that electrically isolates the thermal cutting wire from the electrically-conductive plate.

In these embodiments, the thermally-conductive, electrically-insulative material may be ceramic.

In embodiments, the thermal cutting wire is at least partially disposed within a longitudinally-extending depression defined within the electrically-conductive plate.

In other embodiments, the thermal cutting wire is disposed on at least a portion of at least one of the first or second jaw members and includes a conductive core, an inner ferromagnetic coating disposed about the conductive core, and an outer ferromagnetic coating disposed about the inner ferromagnetic coating.

In these embodiments, the inner ferromagnetic coating may define a first thickness and the outer ferromagnetic coating may define a second, different thickness. Suitably, the first thickness is greater than the second thickness.

In these embodiments, the inner ferromagnetic coating may be formed from a first material and the outer ferromagnetic coating may be formed from a second, different material. The second material may define a relatively greater permeability compared to the first material and/or the first material may define a relatively greater magnetic loss compared to the second material.

In these embodiments, the inner ferromagnetic coating may define a first Curie temperature and the outer ferromagnetic coating may define a second Curie temperature different from the first Curie temperature. In such aspects, the second Curie temperature may be greater than the first Curie temperature.

In some embodiments, the ferromagnetic coating on the thermal cutting wire defines an exposed outer surface and the exposed outer surface defines a roughness configured to facilitate attenuation during ferromagnetic heating.

In these embodiments, the roughness may be patterned. Alternatively, the roughness may be random.

Suitably, the roughness is correlated with a skin depth of the thermal cutting wire. More suitably, a ratio of the roughness to the skin depth is between <NUM>:<NUM> and <NUM>:<NUM>.

The above and other aspects and features of the present disclosure will become more apparent in view of the following detailed description when taken in conjunction with the accompanying drawings wherein like reference numerals identify similar or identical elements.

Referring to <FIG>, a shaft-based electrosurgical forceps provided in accordance with the present disclosure is shown generally identified by reference numeral <NUM>. Aspects and features of forceps <NUM> not germane to the understanding of the present disclosure are omitted to avoid obscuring the aspects and features of the present disclosure in unnecessary detail.

Forceps <NUM> includes a housing <NUM>, a handle assembly <NUM>, a rotating assembly <NUM>, a first activation switch <NUM>, a second activation switch <NUM>, and an end effector assembly <NUM>. Forceps <NUM> further includes a shaft <NUM> having a distal end portion <NUM> configured to (directly or indirectly) engage end effector assembly <NUM> and a proximal end portion <NUM> that (directly or indirectly) engages housing <NUM>. Forceps <NUM> also includes cable "C" that connects forceps <NUM> to an energy source, e.g., an electrosurgical generator "GEN. " Cable "C" includes a wire (or wires) (not shown) extending therethrough that has sufficient length to extend through shaft <NUM> in order to connect to one or both tissue-treating surfaces <NUM>, <NUM> of jaw members <NUM>, <NUM>, respectively, of end effector assembly <NUM> to provide energy thereto. First activation switch <NUM> is coupled to tissue-treating surfaces <NUM>, <NUM> and the electrosurgical generator "GEN" for enabling the selective activation of the supply of energy, e.g., electrosurgical energy, to jaw members <NUM>, <NUM> for treating, e.g., cauterizing, coagulating/ desiccating, and/or sealing, tissue. Second activation switch <NUM> is coupled to a thermal cutting element (not shown) associated with end effector assembly <NUM> and the electrosurgical generator "GEN" (or a separate source of energy) for enabling the selective activation of the supply of energy, e.g., an AC signal, to the thermal cutting element for thermally cutting tissue. Various configurations of thermal cutting elements are detailed below with respect to the embodiments of <FIG>. Further, as an alternative to two separate activation switches <NUM>, <NUM>, a single activation switch (including one or more stages of activation) and/or more than two activation switches (each including one or more stages of activation) are also contemplated.

Handle assembly <NUM> of forceps <NUM> includes a fixed handle <NUM> and a movable handle <NUM>. Fixed handle <NUM> is integrally associated with housing <NUM> and handle <NUM> is movable relative to fixed handle <NUM>. Movable handle <NUM> of handle assembly <NUM> is operably coupled to a drive assembly (not shown) that, together, mechanically cooperate to impart movement of one or both of jaw members <NUM>, <NUM> of end effector assembly <NUM> about a pivot <NUM> between a spaced-apart position and an approximated position to grasp tissue between tissue-treating surfaces <NUM>, <NUM> of jaw members <NUM>, <NUM>. As shown in <FIG>, movable handle <NUM> is initially spaced-apart from fixed handle <NUM> and, correspondingly, jaw members <NUM>, <NUM> of end effector assembly <NUM> are disposed in the spaced-apart position. Movable handle <NUM> is depressible from this initial position to a depressed position corresponding to the approximated position of jaw members <NUM>, <NUM>. Rotating assembly <NUM> includes a rotation wheel <NUM> that is selectively rotatable in either direction to correspondingly rotate end effector assembly <NUM> relative to housing <NUM>.

Referring to <FIG>, a hemostat-style electrosurgical forceps provided in accordance with the present disclosure is shown generally identified by reference numeral <NUM>. Aspects and features of forceps <NUM> not germane to the understanding of the present disclosure are omitted to avoid obscuring the aspects and features of the present disclosure in unnecessary detail.

Forceps <NUM> includes two elongated shaft members 212a, 212b, each having a proximal end portion 216a, 216b, and a distal end portion 214a, 214b, respectively. Forceps <NUM> is configured for use with an end effector assembly <NUM>' similar to end effector assembly <NUM> (<FIG>). More specifically, end effector assembly <NUM>' includes first and second jaw members <NUM>', <NUM>' attached to respective distal end portions 214a, 214b of shaft members 212a, 212b. Jaw members <NUM>', <NUM>' are pivotably connected about a pivot <NUM>'. Each shaft member 212a, 212b includes a handle 217a, 217b disposed at the proximal end portion 216a, 216b thereof. Each handle 217a, 217b defines a finger hole 218a, 218b therethrough for receiving a finger of the user. As can be appreciated, finger holes 218a, 218b facilitate movement of the shaft members 212a, 212b relative to one another to, in turn, pivot jaw members <NUM>', <NUM>' from the spaced-apart position, wherein jaw members <NUM>', <NUM>' are disposed in spaced relation relative to one another, to the approximated position, wherein jaw members <NUM>', <NUM>' cooperate to grasp tissue therebetween.

One of the shaft members 212a, 212b of forceps <NUM>, e.g., shaft member 212b, includes a proximal shaft connector <NUM> configured to connect forceps <NUM> to a source of energy, e.g., electrosurgical generator "GEN" (<FIG>). Proximal shaft connector <NUM> secures a cable "C" to forceps <NUM> such that the user may selectively supply energy to jaw members <NUM>', <NUM>' for treating tissue. More specifically, a first activation switch <NUM> is provided for supplying energy from electrosurgical generator "GEN" (<FIG>) to jaw members <NUM>', <NUM>' to treat tissue upon sufficient approximation of shaft members 212a, 212b, e.g., upon activation of first activation switch <NUM> via shaft member 212a. A second activation switch <NUM> disposed on either or both of shaft members 212a, 212b is coupled to the thermal cutting element (not shown) of one of the jaw members <NUM>', <NUM>' of end effector assembly <NUM>' and to the electrosurgical generator "GEN" (<FIG>) for enabling the selective activation of the supply of energy to the thermal cutting element for thermally cutting tissue. Various configurations of thermal cutting elements are detailed below with respect to the embodiments of <FIG>. Similarly as detailed above with respect to forceps <NUM> (<FIG>), as an alternative to two separate activation switches <NUM>, <NUM>, a single activation switch (including one or more stages of activation) and/or more than two activation switches (each including one or more stages of activation) are also contemplated.

Jaw members <NUM>', <NUM>' define a curved configuration wherein each jaw member is similarly curved laterally off of a longitudinal axis of end effector assembly <NUM>'. However, other suitable curved configurations including curvature towards one of the jaw members <NUM>', <NUM>' (and thus away from the other), multiple curves with the same plane, and/or multiple curves within different planes are also contemplated. Jaw members <NUM>, <NUM> of end effector assembly <NUM> (<FIG>) may likewise be curved according to any of the configurations noted above or in any other suitable manner.

Referring to <FIG>, a robotic surgical instrument provided in accordance with the present disclosure is shown generally identified by reference numeral <NUM>. Aspects and features of robotic surgical instrument <NUM> not germane to the understanding of the present disclosure are omitted to avoid obscuring the aspects and features of the present disclosure in unnecessary detail.

Robotic surgical instrument <NUM> includes a plurality of robot arms <NUM>, <NUM>; a control device <NUM>; and an operating console <NUM> coupled with control device <NUM>. Operating console <NUM> may include a display device <NUM>, which may be set up in particular to display three-dimensional images; and manual input devices <NUM>, <NUM>, by means of which a surgeon may be able to telemanipulate robot arms <NUM>, <NUM> in a first operating mode. Robotic surgical instrument <NUM> may be configured for use on a patient <NUM> lying on a patient table <NUM> to be treated in a minimally invasive manner. Robotic surgical instrument <NUM> may further include a database <NUM>, in particular coupled to control device <NUM>, in which are stored, for example, preoperative data from patient <NUM> and/or anatomical atlases.

Each of the robot arms <NUM>, <NUM> may include a plurality of members, which are connected through joints, and an attaching device <NUM>, <NUM>, to which may be attached, for example, an end effector assembly <NUM>, <NUM>, respectively. End effector assembly <NUM> is similar to end effector assembly <NUM> (<FIG>), although other suitable end effector assemblies for coupling to attaching device <NUM> are also contemplated. End effector assembly <NUM> may be any end effector assembly, e.g., an endoscopic camera, other surgical tool, etc. Robot arms <NUM>, <NUM> and end effector assemblies <NUM>, <NUM> may be driven by electric drives, e.g., motors, that are connected to control device <NUM>. Control device <NUM> (e.g., a computer) may be configured to activate the motors, in particular by means of a computer program, in such a way that robot arms <NUM>, <NUM>, their attaching devices <NUM>, <NUM>, and end effector assemblies <NUM>, <NUM> execute a desired movement and/or function according to a corresponding input from manual input devices <NUM>, <NUM>, respectively. Control device <NUM> may also be configured in such a way that it regulates the movement of robot arms <NUM>, <NUM> and/or of the motors.

Turning to <FIG>, an end effector assembly configured for use as end effector assembly <NUM> of forceps <NUM> (<FIG>), end effector assembly <NUM>' of forceps <NUM> (<FIG>), end effector assembly <NUM> of robotic surgical system <NUM> (<FIG>), or the end effector assembly of any other suitable surgical instrument is shown generally identified by reference numeral <NUM>. End effector assembly <NUM> includes first and second jaw members <NUM>, <NUM> each including a structural frame <NUM>, <NUM>, a jaw housing <NUM>, <NUM>, and a tissue-treating plate <NUM>, <NUM> defining a respective tissue-treating surface <NUM>, <NUM> thereof. One or both of jaw members <NUM>, <NUM> is movable relative to the other from a spaced-apart position to an approximated position for grasping tissue between tissue-treating surfaces <NUM>, <NUM> of tissue-treating plates <NUM>, <NUM>, respectively.

Structural frames <NUM>, <NUM> provide structural rigidity to jaw members <NUM>, <NUM> and extend proximally from jaw housings <NUM>, <NUM> and tissue-treating plates <NUM>, <NUM>, respectively, to enable operable coupling of jaw members <NUM>, <NUM> with one another as well as operable coupling of end effector assembly <NUM> with the distal end portion of a surgical instrument, e.g., distal end portion <NUM> of shaft <NUM> and the distal end portion of the drive assembly of forceps <NUM> (<FIG>).

Jaw housings <NUM>, <NUM> are formed from a thermally and electrically insulative material to electrically isolate structural frames <NUM>, <NUM> from one or both of tissue-treating plates <NUM>, <NUM>. Jaw housings <NUM>, <NUM> encapsulate at least a portion of structural frames <NUM>, <NUM> therein and may be formed from one or more overmolds or in any other suitable manner. In embodiments, jaw housings <NUM>, <NUM> also retain tissue-treating plates <NUM>, <NUM>, respectively, thereon, e.g., capturing legs <NUM>, <NUM> of tissue-treating plates <NUM>, <NUM>, respectively, therein. One or more insulative spacers (not shown), may be incorporated into jaw housings <NUM> and/or <NUM>, e.g., via overmolding.

Tissue-treating plates <NUM>, <NUM>, as noted above, define opposed tissue-treating surfaces <NUM>, <NUM>, respectively. Tissue-treating plates <NUM>, <NUM>, more specifically, define body portions <NUM>, <NUM> having generally planar configurations that define tissue-treating surfaces <NUM>, <NUM>. Each tissue-treating plate <NUM>, <NUM> further includes a leg <NUM>, <NUM> extending from each side thereof. Legs <NUM>, <NUM>, as noted above, facilitate engagement of tissue-treating plates <NUM>, <NUM> on jaw housings <NUM>, <NUM>. Electrical lead wires <NUM>, <NUM> extend through jaw housings <NUM>, <NUM> to electrically connect to the undersides of tissue-treating plates <NUM>, <NUM>, respectively, or are otherwise positioned, to enable the delivery of electrosurgical energy to tissue-treating plates <NUM>, <NUM>, e.g., for treating tissue grasped therebetween.

Continuing with reference to <FIG>, at least one of the tissue-treating plates, e.g., tissue-treating plate <NUM>, defines a longitudinally-extending depression <NUM> extending therealong. Depression <NUM> may define a rounded configuration e.g., having a semi-circular cross-sectional configuration, or any other suitable configuration. A thermal cutting element in the form of a thermal cutting wire <NUM> is disposed at least partially within depression <NUM> and extends longitudinally along at least a portion of tissue-treating surface <NUM>. Depression <NUM> may define a diameter (or height and width, where depression is not semi-circular, that generally approximates, e.g., within <NUM>% or other suitable percentage, the diameter "T" of thermal cutting wire <NUM> to complimentarily receive the at least a portion of thermal cutting wire <NUM> therein, although other configurations are also contemplated. Thermal cutting wire <NUM> may extend about the distal end of jaw member <NUM> and return proximally on the exterior thereof, may extend into jaw member <NUM> at a distal portion of jaw member <NUM>, e.g., at or towards the distal end thereof, and return proximally through jaw member <NUM>, or may define any other suitable configuration, such as those detailed hereinbelow. Depression <NUM> may retain thermal cutting wire <NUM> in position; additionally or alternatively, adhesives, other mechanical engagements, etc. may be used to retain thermal cutting wire in position at least partially within depression <NUM>.

Thermal cutting wire <NUM> may be configured as a ferromagnetic thermal cutting wire including a solid conductive core and a ferromagnetic coating disposed about the solid conductive core. Thermal cutting wire <NUM> may further include an electrically-insulative coating surrounding at least a portion of the ferromagnetic coating to electrically isolate thermal cutting wire <NUM> from tissue-treating surfaces <NUM>, <NUM>. In embodiments, the solid conductive core is copper. In embodiments, the ferromagnetic coating is iron-nickel having a Curie temperature of between <NUM> and <NUM> and, in embodiments, of about <NUM>. Other temperatures or temperature ranges are also contemplated. In embodiments, the electrically-insulative coating is a ceramic.

Thermal cutting wire <NUM>, in embodiments where configured as a ferromagnetic thermal cutting wire, is configured for self-limiting temperature regulation to achieve and maintain a pre-determined temperature. More specifically, in the presence of a high-frequency alternating current, ferromagnetic materials generate large amounts of heat through the hysteresis of the magnetic field in the alternating current. Ferromagnetic materials also have a temperature where they cease to be ferromagnetic, referred to as the Curie temperature. Thus, once the material reaches the Curie temperature, the heating effect essentially ceases. That is, once the material ceases to be ferromagnetic, it becomes a much less effective heater thereby greatly decreasing its thermal output to the point where that temperature is maintained. Thus, the result is a heater that maintains a specific temperature based on its configuration and can be used to ensure sufficient heating and prevent overheating without the need for sensors, feedback mechanisms, and/or control loops. Further, in use, when the heated thermal cutting wire <NUM> contacts tissue and is cooled below the Curie temperature, e.g., by virtue of contact with the relatively cooler tissue, the ferromagnetic thermal cutting wire <NUM> again becomes ferromagnetic and once again becomes an effective heater to automatically heat back to the Curie temperature, thus providing self-regulation.

One or both of jaw members <NUM>, <NUM> includes one or more stop members <NUM> associated with, e.g., disposed on, extending through, or otherwise positioned relative to, tissue-treating plates <NUM>, <NUM> along at least a portion of the lengths thereof. The one or more stop members <NUM> extend beyond tissue-treating surfaces <NUM> and/or <NUM> towards the other tissue-treating surface <NUM>, <NUM> to define a minimum gap distance "G" between jaw members <NUM>, <NUM> at at least one position along the length thereof. This minimum gap distance "G" may be set based on contact between a stop member <NUM> and the opposing tissue-treating plate <NUM>, <NUM>, contact between opposing stop members <NUM>, or in any other suitable manner. It is noted that this minimum gap distance "G" may correspond to the position of jaw members <NUM>, <NUM> in the approximated position; alternatively, the approximated position may correspond to a position wherein tissue-treating surfaces <NUM>, <NUM> are spaced-apart a distance greater than the minimum gap distance "G" in at least one location along the length thereof.

In embodiments, the minimum gap distance "G" plus the depth "D" of depression <NUM>, e.g., the radius of depression <NUM> in embodiments where depression <NUM> is semi-circular, is equal to or greater than the diameter "T" of thermal cutting wire <NUM> to inhibit damage to thermal cutting wire <NUM>, e.g., crushing of thermal cutting wire <NUM> from force applied by jaw members <NUM>, <NUM>.

In use, tissue is grasped between tissue-treating surfaces <NUM>, <NUM> of jaw members <NUM>, <NUM> and electrosurgical energy is supplied to tissue-treating plate <NUM>, <NUM> for conduction through the grasped tissue to treat, e.g., seal, the grasped tissue, e.g., via activation of first activation switch <NUM> (<FIG>). Thereafter, thermal cutting wire <NUM> is activated to thermally cut the treated tissue into to treated tissue portions e.g., via activation of second activation switch <NUM> (<FIG>).

Turning to <FIG>, another end effector assembly configured for use as end effector assembly <NUM> of forceps <NUM> (<FIG>), end effector assembly <NUM>' of forceps <NUM> (<FIG>), end effector assembly <NUM> of robotic surgical system <NUM> (<FIG>), or the end effector assembly of any other suitable surgical instrument is shown generally identified by reference numeral <NUM>. End effector assembly <NUM> includes first and second jaw members <NUM>, <NUM> each including a structural frame <NUM>, <NUM>, a jaw housing <NUM>, <NUM>, and a tissue-treating plate <NUM>, <NUM> defining a respective tissue-treating surface <NUM>, <NUM> thereof. One or both of jaw members <NUM>, <NUM> is movable relative to the other from a spaced-apart position to an approximated position for grasping tissue between tissue-treating surfaces <NUM>, <NUM> of tissue-treating plates <NUM>, <NUM>, respectively.

Jaw housings <NUM>, <NUM> are formed from a thermally and electrically insulative material to electrically isolate structural frames <NUM>, <NUM> from one or both of tissue-treating plates <NUM>, <NUM>. At least jaw housing <NUM> is formed from a high-temperature material, e.g., a material capable of withstanding temperatures of at least <NUM>. Jaw housings <NUM>, <NUM> encapsulate at least a portion of structural frames <NUM>, <NUM> therein and may be formed from one or more overmolds or in any other suitable manner. In embodiments, jaw housings <NUM>, <NUM> also retain tissue-treating plates <NUM>, <NUM>, respectively, thereon, e.g., capturing legs <NUM>, <NUM> of tissue-treating plates <NUM>, <NUM>, respectively, therein. One or more insulative spacers (not shown), may be incorporated into jaw housings <NUM> and/or <NUM>, e.g., via overmolding.

Tissue-treating plates <NUM>, <NUM>, as noted above, define opposed tissue-treating surfaces <NUM>, <NUM>, respectively. Tissue-treating plates <NUM>, <NUM>, more specifically, define body portions <NUM>, <NUM> having generally planar configurations that define tissue-treating surfaces <NUM>, <NUM>. Each tissue-treating plate <NUM>, <NUM> further includes a leg <NUM>, <NUM> extending from each side thereof. Legs <NUM>, <NUM>, as noted above, facilitate engagement of tissue-treating plates <NUM>, <NUM> on jaw housings <NUM>, <NUM>. Electrical lead wires (not shown) extend through jaw housings <NUM>, <NUM> to electrically connect to the undersides of tissue-treating plates <NUM>, <NUM>, respectively, or are otherwise positioned, to enable the delivery of electrosurgical energy to tissue-treating plates <NUM>, <NUM>, e.g., for treating tissue grasped therebetween.

Continuing with reference to <FIG>, the body <NUM>, <NUM> of each tissue-treating plate <NUM>, <NUM> defines a longitudinally-extending channel <NUM>, <NUM> extending through at least a portion of the length thereof that divides the respective tissue-treating plate <NUM>, <NUM> into first and second plate portions 513a, 513b and 523a, 523b, respectively. Channels <NUM>, <NUM> may be laterally centered relative to jaw members <NUM>, <NUM>, respectively, or may be offset towards one side or the other and, thus, first and second plate portions 513a, 513b and 523a, 523b, respectively, may define equal or different widths. One of jaw members, e.g., jaw member <NUM>, includes a high temperature elastomer <NUM>, e.g., an elastomer capable of withstanding temperatures of at least <NUM>, disposed within channel <NUM> and extending therealong. High-temperature elastomer <NUM> defines a tissue-contacting surface <NUM> that may be flush with, recessed relative to, or protruded from tissue-treating surface <NUM>.

The other jaw member, e.g., jaw member <NUM>, includes a thermal cutting element disposed partially within channel <NUM> and protruding therefrom. The thermal cutting element is in the form of a thermal cutting wire <NUM> including one or more wire segments. For example, thermal cutting wire <NUM> may include first and second wire segments <NUM>, <NUM> disposed on the exposed portion of jaw housing <NUM> defined by channel <NUM> and extending in side-by-side relation relative to one another. Wire segments <NUM>, <NUM> may be formed from a single wire that is bent at the distal end thereof, e.g., at a distal end portion of jaw member <NUM>, such that first and second wire segments <NUM>, <NUM> extend longitudinally along jaw member <NUM> at least partially within channel <NUM>. Thermal cutting wire <NUM> is aligned with high-temperature elastomer <NUM> such that, in the approximated position of jaw members <NUM>, <NUM>, thermal cutting wire <NUM> is approximated relative to or contacts high-temperature elastomer <NUM>.

Thermal cutting wire <NUM> may be a ferromagnetic thermal cutting wire configured similarly as detailed above with respect to thermal cutting wire <NUM> (<FIG>) except that, since thermal cutting wire <NUM> is not in contact with tissue-treating surfaces <NUM>, <NUM> and does not contact tissue-treating surfaces <NUM>, <NUM> during use the electrically-insulative layer, e.g., ceramic, need not be provided (so long as sufficient electrical isolation is maintained between the various wires, tissue-treating surface, and/or any other electrical conduits).

One or both of jaw members <NUM>, <NUM> includes one or more stop members <NUM> associated with, e.g., disposed on, extending through, or otherwise positioned relative to, tissue-treating plates <NUM>, <NUM> along at least a portion of the lengths thereof. The one or more stop members <NUM> extend beyond tissue-treating surfaces <NUM> and/or <NUM> towards the other tissue-treating surface <NUM>, <NUM> to define a minimum gap distance (not shown, similar to gap distance "G" (<FIG>)) between jaw members <NUM>, <NUM> at least one position along the length thereof. This minimum gap distance may be set based on contact between a stop member <NUM> and the opposing tissue-treating plate <NUM>, <NUM>, contact between opposing stop members <NUM>, or in any other suitable manner. It is noted that this minimum gap distance may correspond to the position of jaw members <NUM>, <NUM> in the approximated position; alternatively, the approximated position may correspond to a position wherein tissue-treating surfaces <NUM>, <NUM> are spaced-apart a distance greater than the minimum gap distance in at least one location along the length thereof.

In embodiments, the minimum gap distance is equal to or greater than the height "P" that wire segments <NUM>, <NUM> of thermal cutting wire <NUM> protrude beyond tissue-treating surface <NUM> plus or minus any distance the tissue-contacting surface <NUM> of high temperature elastomer <NUM> protrudes or is recessed, respectively, relative to tissue-treating surface <NUM>. Alternatively, the minimum gap distance may be less than the height "P" plus or minus any distance the tissue-contacting surface <NUM> of high temperature elastomer <NUM> protrudes or is recessed. In either configuration, in the approximated position of jaw members <NUM>, <NUM>, cutting wire <NUM> urges tissue grasped between jaw members <NUM>, <NUM> into contact with high temperature elastomer <NUM> to at least partially elastically deform high temperature elastomer <NUM>, although other non-deforming configurations are also contemplated.

In use, tissue is grasped between tissue-treating surfaces <NUM>, <NUM> of jaw members <NUM>, <NUM> and electrosurgical energy is supplied to tissue-treating plate <NUM>, <NUM> for conduction through the grasped tissue to treat, e.g., seal, the grasped tissue. Thereafter, thermal cutting wire <NUM> is activated, thus activating wire segments <NUM>, <NUM>, to thermally cut the treated tissue into to treated tissue portions.

Turning to <FIG>, a jaw member <NUM> of another end effector assembly <NUM> is shown configured for use as end effector assembly <NUM> of forceps <NUM> (<FIG>), end effector assembly <NUM>' of forceps <NUM> (<FIG>), end effector assembly <NUM> of robotic surgical system <NUM> (<FIG>), or the end effector assembly of any other suitable surgical instrument. The other jaw member (not shown) of end effector assembly <NUM> may be similar to jaw member <NUM>, jaw member <NUM> (<FIG>), jaw member <NUM> (<FIG>), combinations thereof, or may define any other suitable configuration. Further, jaw member <NUM> is similar to jaw member <NUM> (<FIG>) and, thus, only the differences therebetween are described in detail below to avoid unnecessary repetition.

Jaw member <NUM> includes a structural frame <NUM>, a jaw housing <NUM>, and a tissue-treating plate <NUM> defining a tissue-treating surface <NUM> thereof. Jaw housing <NUM> is formed from a high-temperature electrically and thermally insulating material, e.g., a material capable of withstanding temperatures of at least <NUM>. Tissue-treating plate <NUM> includes first and second plate portions 623a, 623b defining a channel <NUM> therebetween. Plate portions 623a, 623b may be joined with one another at distal end portions thereof or may remain spaced from one another. Plate portions 623a, 623b are formed via sputtering electrically-conductive material onto jaw housing <NUM> to form plate portions 623a, 623b. However, other suitable manufacturing techniques are also contemplated. One or more electrical lead wires, contacts, or other suitable connectors (not shown) disposed on or within jaw member <NUM> enable electrical connection to plate portions 623a, 623b to permit the delivery of electrosurgical energy thereto.

A thermal cutting element is disposed partially within channel <NUM> and protrudes therefrom. The thermal cutting element is in the form of a thermal cutting wire <NUM> including one or more wire segments (see, e.g., thermal cutting elements <NUM>, <NUM> (<FIG> and <FIG>, respectively)). Thermal cutting wire <NUM> is disposed on the exposed portion of jaw housing <NUM> between plate portions 623a, 623b. Thermal cutting wire <NUM> may be a ferromagnetic thermal cutting wire configured similarly as detailed above with respect to thermal cutting wire <NUM> (<FIG>) except that, since thermal cutting wire <NUM> is not in contact with plate portions 623a, 623b and does not contact plate portions 623a, 623b, or corresponding portions of the other jaw member, the electrically-insulative layer, e.g., ceramic, need not be provided.

Turning to <FIG>, a jaw member <NUM>' of another end effector assembly <NUM>' is shown configured for use as end effector assembly <NUM> of forceps <NUM> (<FIG>), end effector assembly <NUM>' of forceps <NUM> (<FIG>), end effector assembly <NUM> of robotic surgical system <NUM> (<FIG>), or the end effector assembly of any other suitable surgical instrument. The other jaw member (not shown) of end effector assembly <NUM>' may be similar to jaw member <NUM>', jaw member <NUM> (<FIG>), jaw member <NUM> (<FIG>), combinations thereof, or may define any other suitable configuration. Further, jaw member <NUM>' is similar to jaw member <NUM> (<FIG>) and, thus, only the differences therebetween are described in detail below to avoid unnecessary repetition.

Jaw member <NUM>' includes a structural frame <NUM>', a jaw housing <NUM>', and a tissue-treating plate <NUM>' defining a tissue-treating surface <NUM>' thereof. Tissue-treating plate <NUM>' is formed as a single, continuous piece of material (in contrast to the first and second plate portions 623a, 623b of jaw member <NUM> (<FIG>)) via sputtering or other suitable manufacturing method.

Rather than defining a longitudinally-extending channel, jaw member <NUM>' includes a longitudinally-extending electrical insulator <NUM>' (or a series of longitudinally-spaced insulator portions) disposed on tissue-treating surface <NUM>' of tissue-treating plate <NUM>' and extending longitudinally along at least a portion of the length thereof. Electrical insulator <NUM>' may be formed from a ceramic or other suitable material and may be sprayed onto tissue-treating surface <NUM>', deposited onto tissue-treating surface <NUM>', or disposed thereon in any other suitable manner. In such configurations, an electrically-insulative layer surrounding cutting wire <NUM>' need not be provided.

A thermal cutting element is disposed on electrical insulator <NUM>', electrically insulated from tissue-treating surface <NUM>' thereby, and extends along at least a portion of the length of electrical insulator <NUM>'. The thermal cutting element is in the form of a thermal cutting wire <NUM>' including one or more wire segments (see, e.g., thermal cutting elements <NUM>, <NUM> (<FIG> and <FIG>, respectively)). As an alternative to depositing electrical insulator <NUM>' onto tissue-treating surface <NUM>', electrical insulator <NUM>' may be coated on at least a portion of thermal cutting wire <NUM>' to provide an electrically-insulative coating on at least the portion of thermal cutting wire <NUM>' that contacts tissue-treating surface <NUM>' and/or the tissue-treating surface of the other jaw member. Thermal cutting wire <NUM>' may be a ferromagnetic thermal cutting wire configured similarly as detailed above with respect to thermal cutting wire <NUM> (<FIG>), or may be configured similar to thermal cutting elements <NUM>, <NUM> (<FIG>, respectively).

Referring to <FIG>, another configuration of a ferromagnetic thermal cutting wire configured for use as thermal cutting wires <NUM> (<FIG>), <NUM> (<FIG>), <NUM> (<FIG>), and/or <NUM>' (<FIG>) is shown generally identified by reference numeral <NUM>. Ferromagnetic thermal cutting wire <NUM> includes a solid conductive core <NUM>, e.g., copper, an inner ferromagnetic coating <NUM> disposed about the solid conductive core <NUM>, and an outer ferromagnetic coating <NUM> disposed about the inner ferromagnetic coating <NUM>. Inner and outer ferromagnetic coatings <NUM>, <NUM> are formed from different materials and may define different thicknesses and/or overall volumes. In embodiments, inner ferromagnetic coating <NUM> defines a greater overall greater volume than outer ferromagnetic coating <NUM> and is formed from a relatively high magnetic loss material (as compared to outer ferromagnetic coating <NUM>) while outer ferromagnetic coating <NUM> is formed from a material having a relatively higher permeability (as compared to inner ferromagnetic coating <NUM>). As a result of this configuration, current is more concentrated and generates high ohmic loss within outer ferromagnetic coating <NUM> while the rest of the current within the relatively larger volume of the inner ferromagnetic coating <NUM> generates more magnetic loss, e.g., hysteresis loss.

Additionally or alternatively, inner and outer ferromagnetic coatings <NUM>, <NUM> may be configured to define different Curie temperatures. More specifically, outer ferromagnetic coating <NUM> may define a Curie temperature that is less than the Curie temperature of inner ferromagnetic coating <NUM>. As a result of this configuration, when the Curie temperature of the outer ferromagnetic coating <NUM> is first achieved, the output power does not immediately drop to zero (or close to zero); instead, the output power drops to a mid-point of power due to the fact that the inner ferromagnetic coating <NUM> maintains its magnetic properties and continues to be heated (via a lower output power) until it reaches its Curie temperature. The final temperature of thermal cutting wire <NUM> in such embodiments is between the Curie temperature of outer ferromagnetic coating <NUM> and the Curie temperature of inner ferromagnetic coating <NUM>, while the transition of output power (from the relatively high power when both coatings <NUM>, <NUM> are being heated to the relatively lower output power when only inner coating <NUM> is being heated) is relatively smooth.

Thermal cutting wire <NUM> may further include an electrically-insulative, e.g., ceramic, coating surrounding at least a portion of the outer ferromagnetic coating <NUM>, similarly as detailed above.

With reference to <FIG>, another configuration of a ferromagnetic thermal cutting wire configured for use as thermal cutting wires <NUM> (<FIG>), <NUM> (<FIG>), <NUM> (<FIG>), <NUM>' (<FIG>), and/or <NUM> (<FIG>) is shown generally identified by reference numeral <NUM>. Ferromagnetic thermal cutting wire <NUM> may be configured similar to any of the previous embodiments and/or include any of the features thereof in any suitable combination.

Referring to <FIG>, ferromagnetic thermal cutting wire <NUM> further includes a surface roughness <NUM> defined on the outer peripheral surface <NUM> thereof. Due to the skin depth effect, current applied to a ferromagnetic material mostly concentrates on the surface layer (on the order of tens of microns) of the ferromagnetic material. As such, if a surface roughness <NUM> is introduced to increase the overall surface area of the surface layer, the current travel length as well as the average resistivity increases, effectively increasing AC resistance and heating efficiency.

It has been found that if the surface roughness <NUM>, measured as the average peak-to-trough distance defined by the surface roughness <NUM> on the outer peripheral surface <NUM> of the ferromagnetic thermal cutting wire <NUM>, is selected in accordance with the skin depth of the ferromagnetic thermal cutting wire <NUM>, the output power of the ferromagnetic thermal cutting wire <NUM> may be significantly increased. Further, surface roughness <NUM> may also help heat dissipation from ferromagnetic thermal cutting wire <NUM> to tissue by enhancing the wire-tissue interface (contact area) for heat conduction. The surface roughness <NUM> may be formed by a surface treatment process such as etching (e.g., wet or dry plasma etching), a masked coating process, or other suitable process. The surface roughness <NUM> may be patterned or random.

Referring also to <FIG>, as noted above, the output power of the ferromagnetic thermal cutting wire <NUM> may be significantly increased if the surface roughness <NUM> is selected in accordance with the skin depth of the ferromagnetic thermal cutting wire <NUM>. The skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor such that the current density is largest near the surface of the conductor, and decreases with greater depths in the conductor. The electric current flows mainly at this "skin" of the conductor, from the outer surface down to a level called the skin depth. The skin effect causes the effective resistance of the conductor to increase at higher frequencies where the skin depth is smaller, thus reducing the effective cross-section of the conductor. Thus, by configuring ferromagnetic thermal cutting wire <NUM> to correlate the surface roughness <NUM> with the skin depth according to a surface roughness to skin depth ratio, increased attenuation (loss) can be achieved. For example, as illustrated in <FIG>, a study has shown that where the surface roughness is <NUM>-<NUM> times the skin depth, a ratio of between <NUM>:<NUM> and <NUM>:<NUM>, the attenuation (loss) is increased to almost <NUM>% as compared to a non-roughened cutting wire. At ratios above <NUM>:<NUM>, further increase of attenuation (loss) tapers off to a negligible amount. Accordingly, in embodiments, the ferromagnetic thermal cutting wire <NUM> may define a surface roughness to skin depth ratio of from <NUM>:<NUM> to <NUM>:<NUM>, although other ratios are also contemplated.

<FIG> illustrates a reference end effector assembly configured for use as end effector assembly <NUM> of forceps <NUM> (<FIG>), end effector assembly <NUM>' of forceps <NUM> (<FIG>), end effector assembly <NUM> of robotic surgical system <NUM> (<FIG>), or the end effector assembly of any other suitable surgical instrument is shown generally identified by reference numeral <NUM>. End effector assembly <NUM> may be configured similar to any of the end effector assemblies detailed hereinabove, except as explicitly contradicted below. Accordingly, only the different features of end effector assembly <NUM> as detailed below while similarities are summarily described or omitted entirely.

End effector assembly <NUM> includes first and second jaw members <NUM>, <NUM> each including a structural frame <NUM>, <NUM>, a jaw housing <NUM>, <NUM>, and a tissue-treating plate <NUM>, <NUM> defining a respective tissue-treating surface <NUM>, <NUM> thereof. One or both of jaw members <NUM>, <NUM> is movable relative to the other from a spaced-apart position to an approximated position for grasping tissue between tissue-treating surfaces <NUM>, <NUM> of tissue-treating plates <NUM>, <NUM>, respectively. More specifically, structural frames <NUM>, <NUM> extend proximally from jaw housings <NUM>, <NUM> to define proximal flange portions <NUM>, <NUM> enabling pivotable coupling of jaw members <NUM>, <NUM> to one another and the distal end portion of a surgical instrument, e.g., distal end portion <NUM> of shaft <NUM> of forceps <NUM> (<FIG>), about a pivot pin <NUM>. Proximal flange portions <NUM>, <NUM> further define cam slots <NUM>, <NUM>, respectively, for receipt of a cam pin <NUM> to operably couple jaw members <NUM>, <NUM> with one another and a drive assembly such that actuation of the drive assembly pivots at least one of jaw members <NUM>, <NUM> relative to the other between the spaced-apart and approximated positions.

With additional reference to <FIG>, end effector assembly <NUM> further includes a thermal cutting element in the form of a thermal cutting wire <NUM>. Thermal cutting wire <NUM> defines a loop configuration including first and second ends 2032a, 2032b, a body <NUM> having first and second wire segments 2035a, 2035b and including a proximal body portion 2034a and a distal body portion 2034b, and a distal connector portion <NUM> connecting the first and second wire segments 2035a, 2035b with one another. The above-detailed segments and portions are provide for identification purposes only and need not be separate pieces; rather, it is contemplated that thermal cutting wire <NUM> be formed as a continuous, single strand of wire.

First and second ends 2032a, 2032b of thermal cutting wire <NUM> both extend proximally from end effector assembly <NUM>, e.g., through shaft <NUM>, housing <NUM>, and cable "C" of forceps <NUM>, to connect to an energy source, e.g., electrosurgical generator "GEN" (see <FIG>). Proximal body portion 2034a of thermal cutting wire <NUM> extends along proximal flange portion <NUM> of jaw member <NUM> below cam pin <NUM> and pivot pin <NUM>. In embodiments, proximal flange portion <NUM> defines a bifurcated configuration including first and second spaced-apart proximal flange components; in such embodiments, proximal body portion 2034a of thermal cutting wire <NUM> may extend between the proximal flange components. First and second wire segments 2035a, 2035b are disposed a first distance apart from one another along proximal body portion 2034a.

First and second wire segments 2035a, 2035b, along distal body portion 2034b of thermal cutting wire <NUM>, are disposed a second, greater distance apart from one another. First wire segment <NUM> extends on top, alongside, within a channel or depression, or otherwise along the tissue-contacting surface <NUM> defined by tissue-treating plate <NUM> of jaw member <NUM>, e.g., similarly as any of the embodiments detailed hereinabove or in any other suitable configuration, while second wire segment 2035b extends within jaw housing <NUM>. In other embodiments, second wire segment 2035b extends along an outer exterior surface of jaw housing <NUM>, or extends partially within jaw housing <NUM> and partially along the outer exterior surface thereof. The portion of first wire segment 2035a extending along distal body portion 2034b of thermal cutting wire <NUM> functions as a cutting wire to cut tissue grasped between jaw members <NUM>, <NUM>, e.g., to thermally cut sealed tissue, similarly as detailed above with respect to previous embodiments.

Distal connector portion <NUM> of thermal cutting wire <NUM> extends about at least a portion of the distal tip of jaw member <NUM>, e.g., distally about the distal tip of jaw housing <NUM>, to interconnect the distal ends of first and second wire segments 2035a, 2035b with one another. As such, distal connector portion <NUM> is exposed at the distal tip of jaw member <NUM> and functions as a cutting wire to cut tissue distally adjacent jaw member <NUM>, e.g., for thermal blunt dissection.

Thermal cutting wire <NUM> may be configured as a ferromagnetic cutting wire. However, only the portion of first wire segment 2035a extending along distal body portion 2034b of thermal cutting wire <NUM> and distal connector portion <NUM> of thermal cutting wire <NUM> are ferromagnetic, e.g., include a ferromagnetic coating, such that only these portions are heated when an alternating current (AC signal) is applied to thermal cutting wire <NUM>. The remainder of thermal cutting wire <NUM> may be coated with a thermally and/or electrically insulative material.

In embodiments, the portion of first wire segment 2035a extending along distal body portion 2034b of thermal cutting wire <NUM>, defining a zone "A," has a first Curie temperature while distal connector portion <NUM> of thermal cutting wire <NUM>, defining a zone "B," has a second, different Curie temperature. The different Curie temperatures may be achieved by the use of different ferromagnetic coatings, different layers (types, numbers, etc.) of ferromagnetic coating, different thicknesses, or in any other suitable matter. In other embodiments, the portion of first wire segment 2035a extending along distal body portion 2034b of thermal cutting wire <NUM> and distal connector portion <NUM> of thermal cutting wire <NUM> define the same configuration and the same Curie temperature. The portion of first wire segment 2035a extending along distal body portion 2034b of thermal cutting wire <NUM> and distal connector portion <NUM> of thermal cutting wire <NUM> may be configured similarly or differently and may each include any or all of the features detailed above with respect to ferromagnetic thermal cutting wire <NUM> (<FIG>) or may define any other suitable configuration. The portion of first wire segment 2035a extending along distal body portion 2034b of thermal cutting wire <NUM> and distal connector portion <NUM> of thermal cutting wire <NUM> may be coated with an electrically-conductive material, e.g., ceramic, to electrically isolate the same from tissue-treating plates <NUM>, <NUM>.

Turning to <FIG>, an end effector assembly according to the accompanying claims configured for use as end effector assembly <NUM> of forceps <NUM> (<FIG>), end effector assembly <NUM>' of forceps <NUM> (<FIG>), end effector assembly <NUM> of robotic surgical system <NUM> (<FIG>), or the end effector assembly of any other suitable surgical instrument is shown generally identified by reference numeral <NUM>. End effector assembly <NUM> is similar to end effector assembly <NUM> (<FIG>) and may include any of the features thereof, except as explicitly contradicted below. Accordingly, only the different features of end effector assembly <NUM> as detailed below while similarities are summarily described or omitted entirely.

End effector assembly <NUM> includes first and second jaw members <NUM>, <NUM> each including a structural frame <NUM>, <NUM>, a jaw housing <NUM>, <NUM>, and a tissue-treating plate <NUM>, <NUM> defining a respective tissue-treating surface <NUM>, <NUM> thereof. One or both of jaw members <NUM>, <NUM> is movable relative to the other from a spaced-apart position to an approximated position for grasping tissue between tissue-treating surfaces <NUM>, <NUM> of tissue-treating plates <NUM>, <NUM>, respectively.

With additional reference to <FIG>, end effector assembly <NUM> further includes a thermal cutting assembly including first and second wires 2130a, 2130b. First wire 2130a is configured similar to and may include any of the features of thermal cutting wire <NUM> (<FIG>). That is, first wire 2130a defines a loop configuration including first and second ends 2132a, 2132b, a body <NUM> having first and second wire segments 2135a, 2135b and including a proximal body portion 2134a and a distal body portion 2134b, and a distal connector portion <NUM> connecting the first and second wire segments 2135a, 2135b with one another.

First wire 2130a may be configured as a ferromagnetic cutting wire wherein the portion of first wire segment 2135a extending along distal body portion 2134b of first wire 2130a, defining zone "A," and distal connector portion <NUM> of first wire 2130a, defining zone "B," are ferromagnetic, e.g., include a ferromagnetic coating, such that only these portions are heated when an alternating current (AC signal) is applied to thermal cutting wire <NUM>. The remainder of first wire 2130a may be coated with a thermally and/or electrically insulative material.

Second wire 2130b branches off from first wire 2130a between first wire segment 2135a and distal connector portion <NUM>. Second wire 2130b, more specifically, extends from first wire 2130a through an opening defined within tissue-treating plate <NUM> and/or jaw housing <NUM> into or through jaw housing <NUM> and returns proximally within jaw housing <NUM>, along an outer exterior surface of jaw housing <NUM>, or partially within jaw housing <NUM> and partially along the outer exterior surface thereof, eventually extending proximally from end effector assembly <NUM>, e.g., through shaft <NUM>, housing <NUM>, and cable "C" of forceps <NUM>, to connect to an energy source, e.g., electrosurgical generator "GEN" (see <FIG>). Second wire 2130b may be coated with a thermally and/or electrically insulative material.

As a result of the above-detailed configuration, wherein the proximal end of second wire 2130b as well as the first and second ends 2132a, 2132b of first wire 2130a are connected to the energy source e.g., electrosurgical generator "GEN" (see <FIG>), an alternating current (AC signal) can be supplied to selectively energize zone "A" and/or zone "B. " Further, zone "A" and zone "B" may define similar or different Curie temperatures, e.g., via use of different ferromagnetic coatings, different layers of ferromagnetic coating, different thicknesses, or in any other suitable matter, and/or may be configured similarly or differently including any or all of the features detailed above with respect to ferromagnetic thermal cutting wire <NUM> (<FIG>) or may define any other suitable configuration. Zone "A" and/or zone "B" may also include a ceramic or other suitable electrically-insulative coating, e.g., to electrically isolate the same from tissue-treating plates <NUM>, <NUM>.

In embodiments, rather than first wire 2130a defining zone "A" and zone "B" and second wire 2130b branching from first wire 2130a, first and second wires 2130a, 2130b may be separate from one another with each defining one of zone "A" and zone "B" and each including first and second ends that extend proximally to connect to an energy source, e.g., electrosurgical generator "GEN" (see <FIG>). Other configurations are also contemplated.

With reference to <FIG>, as an alternative to or in addition to providing one or more thermal cutting wires, one or both of the jaw members of any of the end effector assemblies detailed herein above, or may other suitable end effector assembly, may include a thermal cutting element <NUM> disposed on the tissue-treating plate <NUM> thereof. Thermal cutting element <NUM> includes one or more sets of layers <NUM> with each set of layers <NUM> including: an electrical insulation layer <NUM>, e.g., ceramic; a conductive core layer <NUM>, e.g., copper; and a ferromagnetic layer <NUM>, e.g., iron-nickel. With respect to the first set of layers <NUM>, electrical insulation layer <NUM> is disposed on tissue-treating plate <NUM> to electrically isolate thermal cutting element <NUM> from tissue-treating plate <NUM>, ferromagnetic layer <NUM> is disposed on insulation layer <NUM>, and conductive core layer <NUM> is disposed on ferromagnetic layer <NUM> and connects to a source of energy to enable current flow through thermal cutting element <NUM> while ferromagnetic layer <NUM> enables ferromagnetic heating with automatic Curie temperature control upon the flow of current through conductive core layer <NUM>.

With respect to the second set of layers <NUM>, electrical insulation layer <NUM> is disposed on the conductive core layer <NUM> of the first set of layers <NUM> to electrically isolate the first and second layers from one another, conductive core layer <NUM> is disposed on electrical insulation layer <NUM> and connects to a source of energy to enable current flow through thermal cutting element <NUM>, and ferromagnetic layer <NUM> is disposed on conductive core layer <NUM> and enables ferromagnetic heating with automatic Curie temperature control upon the flow of current through conductive core layer <NUM>.

In embodiments, multiple ferromagnetic layers <NUM> may be stacked on top of one another and/or the exposed surface of the ferromagnetic layer(s) <NUM> may be roughened, similarly as detailed above. Further, additional sets of layers <NUM> similar as the first set of layers <NUM> may be stacked on top of one another with the second set of layers <NUM> disposed on the upper-most set of layers <NUM>. Alternatively, only a single set of layers <NUM> may be provided, e.g., similar as the second set of layers <NUM>.

Referring to <FIG>, as an alternative to or in addition to providing one or more thermal cutting wires, one or both of the jaw members of any of the end effector assemblies detailed herein above, or may other suitable end effector assembly, may include a thermal cutting element <NUM> disposed on an exposed surface of the jaw housing <NUM> thereof (where jaw housing <NUM> is formed from a high-temperature electrically and thermally insulating material, e.g., a material capable of withstanding temperatures of at least <NUM>). The exposed surface of the jaw housing <NUM> may be an exposed surface defined by a channel within the tissue-treating plate of the jaw member, an exposed surface defined between tissue-treating plate portions of the jaw member; an outer exterior, e.g., side or back surface, of the jaw housing <NUM>, or any other suitable exposed surface of jaw housing <NUM>.

Thermal cutting element <NUM> includes one or more sets of layers <NUM> with each set of layers <NUM> including a conductive core layer <NUM>, e.g., copper; and a ferromagnetic layer <NUM>, e.g., iron-nickel. Conductive core layer <NUM> is disposed on jaw housing <NUM> and connects to a source of energy to enable current flow through thermal cutting element <NUM> while ferromagnetic layer <NUM> is disposed on conductive core layer <NUM> and enables ferromagnetic heating with automatic Curie temperature control upon the flow of current through conductive core layer <NUM>. In embodiments, multiple ferromagnetic layers <NUM> may be stacked on top of one another and/or the exposed surface of the ferromagnetic layer(s) <NUM> may be roughened, similarly as detailed above. Further, additional sets of layers <NUM> similarly arranged may be disposed on the first set of layers <NUM> with an insulation layer, e.g., ceramic, disposed therebetween to provide electrical isolation.

Claim 1:
An electrosurgical instrument (<NUM>, <NUM>), comprising:
an end effector assembly (<NUM>, <NUM>', <NUM>, <NUM>) including first and second jaw members (<NUM>, <NUM>, <NUM>', <NUM>', <NUM>, <NUM>, <NUM>, <NUM>), at least one of the first or second jaw members movable relative to the other from a spaced-apart position to an approximated position to grasp tissue between first and second opposed surfaces of the first and second jaw members, respectively, the first jaw member (<NUM>, <NUM>, <NUM>) including:
a thermal cutting wire (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, 2130a) including a first portion (2035a, 2135a) extending distally along at least a portion of a length of the first opposed surface (<NUM>, <NUM>),
wherein the thermal cutting wire further comprises:
a second portion (<NUM>, <NUM>) extending from the first portion about a distal tip of the first jaw member; and
a third portion (2035b, 2135b) extending from the second portion proximally at least one of through the first jaw member or along an outer exterior surface of the first jaw member,
characterized in that:
the first and second portions (2035a, 2135a, 2035b, 2135b) of the thermal cutting wire (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, 2130a) each include a ferromagnetic coating (<NUM>) such that the first and second portions are ferromagnetically heated and provide automatic Curie temperature control upon supply of an AC signal thereto; and
the electrosurgical instrument further comprises a branch wire (2130b) branching off from the thermal cutting wire between the first portion (2135a) and the second portion (<NUM>) and extending proximally at least one of through the first jaw member (<NUM>) or along an outer exterior surface of the first jaw member to enable independent activation of the first and second portions.