Abstract:
Bipolar electrosurgical forceps for use with a robotic surgical system. Electrodes on a first grasping jaw member align with corresponding electrodes on a second jaw member, allowing localized energy to seal tissue between the first and second jaw members. The first jaw member has an open centerline slot, exposing the tissue in the slot. The exposed tissue enables a second, similar forceps to be used with an opposing arm to treat the tissue in the slot. In embodiments, the precise motion of the robotic arms supporting the first and second forceps guides a distal tip electrode of the second forceps precisely within the open centerline slot of the first forceps to treat tissue. In this manner, the complex assemblies and control systems associated with moving blades of conventional electrosurgical forceps are eliminated.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a U.S. National Stage Application filed under 35 U.S.C. §371(a) of International Patent Application No. PCT/US2014/063653, filed Nov. 3, 2014, which claims the benefit to U.S. Provisional Patent Application No. 61/917,591, filed Dec. 18, 2013, the entire disclosure of each of which is incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present disclosure relates to surgical instruments, and more specifically, to improved electrosurgical jaw assemblies for use with robotic surgical systems. 
         [0004]    2. Background of Related Art 
         [0005]    Electrosurgery uses alternating current electrical signals to cut or coagulate biologic tissue endogenically. Electrosurgery techniques have been used in robotic surgery by passing these electrical signals through electrodes in end effectors attached to the ends of robotic arms. In some instances, two different types of end effectors are used. A first end effector type includes an active electrode, and a second end effector type includes a return electrode to which current passing through the patient&#39;s body from the active electrode flows. Having two different end effector types adds cost and complexity due to the need to obtain and install both end effector types on different arms corresponding to a user preferred orientation, such as a preferred left-right orientation of the active and return electrodes on the arms, in order to perform some types of electrosurgery. 
         [0006]    These two types of end effectors are also used in some instances exclusively for electrosurgery. If a user needed to perform another function, such as grasping, the user would have to switch end effectors. Such switching of end effectors during surgery lengthens surgical procedure times and increases costs, because separate grasping and electrosurgical end effectors must be obtained and interchanged. 
         [0007]    A single end effector that eliminates the need for different active and return electrode end effectors in electrosurgical applications, and which reduces the need to switch end effectors during surgery, would be a welcome advance. 
       SUMMARY 
       [0008]    The dexterity of robotic surgical systems allows for arrangements of multiple instruments that allow for a level of functionality that might be challenging in a single instrument. According to one aspect of the present disclosure, a pair of grasper-like bipolar instruments is presented which, in combination with each other, can be mated to perform an array of bipolar tasks. These tasks include, without limitation, bipolar cutting, bipolar vessel sealing, and hemostasis of small vessels using bipolar coagulation. 
         [0009]    According to another aspect of the present disclosure, a first robotic arm includes a first bipolar grasping forceps having a first bipolar grasping jaw member with two distinct electrodes embedded within an insulative material. The electrodes on the first grasping jaw member align with corresponding electrodes (e.g., ground or return electrodes) on a second jaw member, allowing localized energy to seal tissue between the first and second jaw members. The first jaw member has a centrally-disposed slot defined therein where energy will not pass to the second jaw member during the tissue sealing process, thus allowing the tissue in the slot to remain unsealed or untreated. After the tissue is sealed, a second, similar bipolar grasping forceps may be used in a second, opposing robotic arm to treat (e.g., cut, seal, etc.) the tissue in the slot. 
         [0010]    In one embodiment, the disclosed bipolar forceps has an insulated protrusion with a small electrode at the distal tip. Because the area of the tip electrode is small, current density is relatively high, allowing the tip energy to cut the tissue in the slot as the energy conducts from the tip to a contact pad (electrode) on the jaw member opposite of the slot. Electrodes in the jaw member are configured to enable sealing energy to be conducted between the outer sealing pads of the first forceps, and cutting energy to be conducted between the protruding tip electrode of the second forceps and the central cutting electrode of the first forceps to perform a “two-handed” sealing and/or cutting operation. Advantageously, the high-precision motion of the robotic arms supporting the first and second forceps facilitate the operation by guiding the distal tip electrode of the second forceps precisely within the open centrally-disposed slot of the first forceps. 
         [0011]    In another embodiment, the disclosed bipolar forceps may additionally or alternatively include an insulated longitudinal ridge on the reverse side of the second jaw member having a uninsulated top surface. The ridge is configured to fit within the open centrally-disposed slot of the first jaw member of another bipolar forceps to perform electrosurgical sealing and/or cutting operations. 
         [0012]    In some embodiments, the cutting procedure is performed at least in part by a preprogrammed set of instructions executable on a processor operatively coupled to the forceps, generator, and/or robotic arms which choreographs the cutting and/or sealing motion between the two forceps. 
         [0013]    In yet another embodiment, the disclosed bipolar forceps may additionally or alternatively include a cutting blade positioned within a base of the centrally-disposed slot providing protection for the blade and configured to facilitate cutting sutures when a suture is pulled into the slot. 
         [0014]    Advantageously, the design of a bipolar sealing instrument in accordance with the present disclosure is greatly simplified, because the complex assemblies and control systems associated with moving blades of conventional electrosurgical forceps are eliminated, which, in turn, reduces costs, enhances reliability, and may improve patient outcomes. In addition, a single device type could be used to easily ligate and cut tissue, allowing procedures to move quickly without the interruptions associated with changing instruments frequently. This further reduces costs by decreasing the number of instruments used, reducing consumables, and lowering disposal and sterilization costs. 
         [0015]    In another aspect of the present disclosure, a method of providing cooperative or two-handed sealing and cutting includes connecting opposite first and second forceps with opposite polarities, e.g., the right hand slot grip seals against the right hand base grip and the left hand base grip cuts against the right hand base grip. Alternatives may include providing a single conductive pad on the un-slotted jaw member or positioning the cutting protrusion on the outer edge of the second jaw member. 
         [0016]    The present disclosure relates to an electrosurgical end effector for use with a robot arm of a robotic surgical system. In one embodiment, the end effector includes a wrist assembly and a jaw assembly. The wrist assembly includes a proximal hub defining a longitudinal axis, and a distal hub pivotally connected to the proximal hub. The proximal hub and the distal hub are pivotable about a first pivot axis that is oriented transverse to the longitudinal axis of the proximal hub. 
         [0017]    The jaw assembly includes first and second jaw members pivotally connected to the distal hub of the wrist assembly. The first jaw member includes a housing, and a longitudinal slot defined in the housing of the first jaw member. The longitudinal slot forms first and second grasping members, where each grasping member includes a grasping surface configured to face an opposing grasping surface of the second jaw member. The first jaw member includes a first sealing electrode disposed on the first grasping surface, and a second sealing electrode disposed on the second grasping surface. 
         [0018]    The second jaw member includes a housing, and a grasping surface that is configured to face the grasping surface of the first jaw member. The second jaw member includes first and second return electrodes longitudinally disposed on the grasping surface, where the first and second return electrodes are configured to oppose the corresponding first and second sealing electrodes of the first jaw member. The second jaw member includes a third return electrode longitudinally disposed on the grasping surface located centrally between first and second return electrodes, where the third return electrode is configured to oppose the longitudinal slot of the first jaw member. At least one of the housing and the grasping surface of the first and/or second jaw member may be formed from ceramic material. 
         [0019]    In some embodiments, the electrosurgical end effector includes a cutting electrode assembly having a support ridge disposed longitudinally on the top portion of the housing of the second jaw member, and a longitudinal electrode is positioned along the top of the support ridge. The cutting electrode assembly may be configured to be operably received within the longitudinal slot. In some embodiments, the cutting electrode assembly is movable between a first (raised) position where the longitudinal electrode is positioned above the top portion of the housing of the second jaw member, and a second (lowered) position where the longitudinal electrode is positioned closer to, or flush with, the top portion of the housing of the second jaw member. 
         [0020]    In yet other embodiments, the electrosurgical end effector includes a tip electrode assembly having a tip electrode support extending distally from a distal portion of the housing of the second jaw member, and a tip electrode disposed on a distal tip of the tip electrode support. The tip electrode assembly may be configured to be operably received within the longitudinal slot. In some embodiments, the tip electrode assembly is movable between a first (raised) position where the tip electrode is positioned above the surface of a distal portion of the housing of the second jaw member, and a second (lowered) position where the tip electrode is positioned closer to, or flush with, the surface of a distal portion of the housing of the second jaw member. 
         [0021]    In still other embodiments, at least one of the first sealing electrode, second sealing electrode, first return electrode, second return electrode, and third return electrode may be flush with grasping surface and/or may be disposed upon the grasping surface. The first sealing electrode, second sealing electrode, first return electrode, second return electrode, and third return electrode may be configured for independent electrical communication with an electrosurgical generator. 
         [0022]    In another aspect of the present disclosure, a robotic surgical system for performing electrosurgical procedures is described. In an example embodiment, the system includes an end effector operably coupled to a robot arm. The end effector includes a first jaw member having a housing and a longitudinal slot defined in the housing which forms first and second grasping members. Each grasping member has a grasping surface configured to face an opposing grasping surface of a second jaw member. The first jaw member includes a first sealing electrode disposed on the first grasping surface, and a second sealing electrode disposed on the second grasping surface. The end effector includes a second jaw member having a housing, and a grasping surface included in the housing that is configured to face the grasping surface of the first jaw member. The second jaw member includes first and second return electrodes longitudinally disposed on the grasping surface which are configured to oppose corresponding first and second sealing electrodes of the first jaw member. The second jaw member includes a third return electrode longitudinally disposed on the grasping surface located centrally between the first and second return electrodes. The third return electrode is configured to oppose the longitudinal slot of the first jaw member. 
         [0023]    The example system includes a control device configured to manipulate at least one of the robot arm and the end effector according to a user input, and an electrosurgical generator in operable communication with the control device and the end effector. The generator is configured to selectively deliver electrosurgical energy to at least one of the first sealing electrode, second sealing electrode, first return electrode, second return electrode, and third return electrode. In some embodiments, the system includes a second end effector operably coupled to a second robot arm. 
         [0024]    The control device may be configured to manipulate at least one of the robot arm and at least one of the end effectors according to a preprogrammed sequence of actions. In some embodiments, the preprogrammed sequence of actions includes introducing the cutting electrode assembly of the first end effector into the longitudinal slot of the second end effector to grasp tissue therebetween, delivering electrosurgical energy between the cutting electrode assembly of the first end effector and the return electrode of the second end effector to treat the tissue grasped therebetween, withdrawing the cutting electrode assembly of the first end effector from the longitudinal slot of the second end effector. 
         [0025]    In embodiments, the preprogrammed sequence of actions may include introducing the tip electrode assembly of the first end effector into a first end of the longitudinal slot of the second end effector, delivering electrosurgical energy between the cutting electrode assembly of the first end effector and the third return electrode of the second end effector to treat tissue grasped between the first and second jaw members of the second end effector and exposed within the longitudinal slot thereof, moving the tip electrode assembly of the first end effector along the longitudinal slot of the second end effector toward a second end thereof to treat the exposed tissue, and withdrawing the tip electrode assembly of the first end effector from the longitudinal slot of the second end effector. 
         [0026]    In embodiments, the preprogrammed sequence of actions may include delivering electrosurgical energy between at least one of the first sealing electrode and the first return electrode, and/or the second sealing electrode and the second return electrode. 
         [0027]    In another aspect of the present disclosure, a method of performing electrosurgery is presented. The method includes positioning tissue between a cutting electrode of a first end effector associated with a first robotic arm and a return electrode of a second end effector associated with a second robotic arm. The cutting electrode is moved toward the return electrode to grasp the tissue therebetween. Electrosurgical energy is delivered between the cutting electrode and the return electrode to treat the tissue grasped therebetween, and the cutting electrode is withdrawn from the return electrode, which releases the treated tissue. 
         [0028]    In some embodiments, the method may include grasping the tissue between at least one of a first sealing electrode and a first return electrode of the first end effector and/or at least one of a second sealing electrode and a first return electrode of the first end effector, and delivering electrosurgical energy between at least one of the first sealing electrode and the first return electrode of the first end effector, and/or the second sealing electrode and the second return electrode of the first end effector. 
         [0029]    In yet other embodiments, the method may include moving the cutting electrode longitudinally along the return electrode to treat the tissue therebetween. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    Further details and aspects of example embodiments in accordance with the present disclosure are described in more detail below with reference to the appended Figures, wherein: 
           [0031]      FIG. 1  is a schematic illustration of a medical workstation and operating console in accordance with the present disclosure; 
           [0032]      FIG. 2A  is a top, perspective view of an end effector according to an embodiment of the present disclosure, for use in the medical workstation of  FIG. 1 , illustrating a jaw assembly thereof in a closed condition; 
           [0033]      FIG. 2B  is a top, perspective view of the end effector of  FIG. 2A  illustrating the jaw assembly in an open condition; 
           [0034]      FIG. 2C  is a bottom, perspective view of the end effector of  FIG. 2A  illustrating a cutting electrode disposed on a lower jaw member thereof; 
           [0035]      FIG. 3A  is a view of a non-grasping side of an upper jaw member in accordance with the present disclosure; 
           [0036]      FIG. 3B  is a view of a grasping side of the upper jaw member in accordance with the present disclosure; 
           [0037]      FIG. 3C  is a perspective view of the upper jaw member in accordance with the present disclosure; 
           [0038]      FIG. 4A  is a view of the non-grasping side of the lower jaw member in accordance with the present disclosure; 
           [0039]      FIG. 4B  is a view of the grasping side of the lower jaw member in accordance with the present disclosure; 
           [0040]      FIG. 4C  is a perspective view of the lower jaw member in accordance with the present disclosure; 
           [0041]      FIG. 4D  is a perspective view of the lower jaw member showing a cutting electrode in a retracted position in accordance with the present disclosure; 
           [0042]      FIG. 4E  is a perspective view of the lower jaw member a distal tip electrode in a retracted position in accordance with the present disclosure; 
           [0043]      FIG. 5A  illustrates two pair of end effectors cooperating to treat tissue in accordance with the present disclosure; 
           [0044]      FIG. 5B  illustrates another aspect of the two pair of end effectors cooperating to treat tissue; 
           [0045]      FIG. 6  illustrates a two pair of end effectors cooperating to treat tissue in accordance with another embodiment the present disclosure; and 
           [0046]      FIG. 7  illustrates another embodiment of the end effector of the present disclosure for use with the medical workstation of  FIG. 1 , illustrating a jaw assembly having a tissue manipulation feature. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0047]    Particular embodiments of the present disclosure are described hereinbelow with reference to the accompanying drawings; however, it is to be understood that the disclosed embodiments are merely examples of the disclosure, which may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. In the drawings and in the descriptions that follow, the term “proximal,” as is traditional, shall refer to the end of the instrument that is closer to the user, while the term “distal” shall refer to the end that is farther from the user. In addition, as used herein in the description and in the claims, terms referencing orientation, e.g., “top”, “bottom”, “upper”, “lower”, “left”, “right”, and the like, are used with reference to the figures and features shown and described herein. It is to be understood that embodiments in accordance with the present disclosure may be practiced in any orientation without limitation. In this description, as well as in the drawings, like-referenced numbers represent elements which may perform the same, similar, or equivalent functions. 
         [0048]    Referring initially to  FIG. 1 , a medical workstation is shown as workstation  1  and generally includes a plurality of robot arms  2  and  3 , a control device  4 , and an operating console  5  coupled with the control device  4 . Operating console  5  includes a display device  6 , which is configured to display three-dimensional images of the surgical site, and manual input devices  7 ,  8 , which allow a person (not shown), for example a surgeon, to telemanipulate robot arms  2 ,  3  and instruments attached thereto. 
         [0049]    Each of the robot arms  2 ,  3  includes a plurality of articulating members  11 ,  12  and  13 ,  14 , respectively, which are connected by joints  15 ,  16  and are configured to facilitate the telemanipulation of robot arms  2 ,  3  with respect to patient P. Attaching devices  9  and  10  are disposed at distal ends of arms  2 ,  3  and are each configured to support an end effector  100 ,  100 ′ (see  FIG. 5A ). 
         [0050]    Robot arms  2 ,  3  may be driven by electric drives (not shown) that are connected to control device  4 . Control device  4  (e.g., a computer) is configured to activate the drives by means of a computer program associated therewith in such a way that robot arms  2 ,  3 , their attaching devices  9 ,  10  and respective end effectors  100 ,  100 ′ execute a desired movement, which may be performed according to a movement defined by user inputs to manual input devices  7 ,  8  and, additionally or alternatively, movements defined by one or more algorithms associated with the computer program of control device  4 . Control device  4  may also be configured in such a way that it regulates the movement of robot arms  2 ,  3  and/or of the electric drives. 
         [0051]    Medical workstation  1  is configured for use on a patient P lying on a patient table  12  to be treated in a minimally invasive manner by means of end effector  100 . Medical workstation  1  may also include more than two robot arms  2 ,  3 , the additional robot arms likewise being connected to control device  4  and being telemanipulable by means of operating console  5  and otherwise similarly to robot arms  2 ,  3 . A medical instrument (e.g., end effector  100 ) may also be attached to the additional robot arm(s). 
         [0052]    Medical workstation  1  includes an electrosurgical generator  14  that is configured to receive inputs from operating console  5  and/or control device  4  and selectively deliver monopolar and/or bipolar electrosurgical energy to end effector(s)  100 ,  100 ′ of robot arms  2 ,  3 . 
         [0053]    Reference may be made to U.S. Patent Publication No. 2012/0116416, filed on Nov. 3, 2011, entitled “Medical Workstation,” the entire contents of which are incorporated herein by reference, for a detailed discussion of the construction and operation of the medical workstation  1 . 
         [0054]    Turning now to  FIGS. 2A-2C , end effector  100  connects to robot arms  2 ,  3  and is manipulatable by control device  4  and includes a wrist assembly  110 , and a jaw assembly  150  pivotally connected to the wrist assembly  110 . Wrist assembly  110  includes a proximal hub  112 , in the form of a distally extending clevis, defining a first longitudinal axis “X1.” Proximal hub  112  defines a first pivot axis “A” that is oriented orthogonally to the first longitudinal axis “X1.” In an embodiment, first pivot axis “A” may extend through the first longitudinal axis “X1.” Proximal hub  112  includes a pair of spaced-apart, opposed uprights  112   a ,  112   b  that align along first pivot axis “A”. 
         [0055]    Wrist assembly  110  further includes a distal hub  114  pivotally connected to uprights  112   a ,  112   b  of proximal hub  112 . Distal hub  114  includes a distally extending clevis  115  configured to define a second longitudinal axis “X2.” Distal hub  114  defines a second pivot axis “B” that is oriented orthogonally to the first pivot axis “A” and orthogonally to the first longitudinal axis “X1.” In an embodiment, when the first longitudinal axis “X1” is parallel with the second longitudinal axis “X2” (i.e., end effector  100  is in an axially aligned orientation), second pivot axis “B” may extend through first longitudinal axis “X1.” Distal hub  114  includes a pair of spaced apart, opposed uprights  114   a ,  114   b  that align along second pivot axis “B”. 
         [0056]    Jaw assembly  150  includes a pair of jaw members  172 ,  174  separately and independently connected to corresponding support bases  152 ,  154 . As best seen in  FIGS. 3C and 4C , each jaw member  172 ,  174  includes a pivot point  161 ,  162  about which each jaw member  172 ,  174  pivots. Pivot points  161 ,  162  are spaced in axial alignment to define a common jaw pivot axis coincident with pivot axis “B” of distal hub  114 . Each jaw member  172 ,  174  includes a respective proximal end  162   a ,  164   a  and a respective distal end  162   b ,  164   b . A pin  175  or the like pivotally connects each pivot point  161 ,  162  of respective jaw member  172 ,  174  to distal hub  114  to enable jaw member  172 ,  174  to move between a first (open) position as illustrated in  FIG. 2B  and a second (closed) position as illustrated in  FIG. 2A . 
         [0057]    With reference now to  FIGS. 3A-3C , jaw member  172  includes a longitudinal slot  173  defined therein thereby forming first and second grasping members  172   a ,  172   b  in a fork-like arrangement. Longitudinal slot  173  is configured to receive electrode  186  of jaw member  174 , as will be described in more detail below. Jaw member  172  includes a jaw housing  195  having a grasping surface  194  (see  FIG. 3B ). Jaw housing  195  and/or grasping surface  194  may be formed from a high-strength, heat-resistant, and electrically insulative material, such as, without limitation, ceramic, zirconia, sialons, and the like. Grasping surface  194  may be smooth, serrated, or have opposing or interlocking teeth. In some embodiments, jaw housing  195  may be formed in full or in part from a metallic material. Grasping surface  194  is configured to face an opposing grasping surface  184  of jaw member  174  ( FIGS. 2B and 2C ) when jaw member  172  and jaw member  174  are assembled as jaw assembly  150 . 
         [0058]    A first and second sealing electrode  190   a ,  190   b  are disposed on the respective grasping surfaces  194  of first and second grasping members  172   a ,  172   b  (see  FIG. 3B ). In some embodiments, first and second electrodes  190   a ,  190   b  are embedded within grasping surface  194  such that the tissue-contacting surface of the first and second electrodes  190   a ,  190   b  are substantially flush with grasping surface  194  (e.g., within acceptable manufacturing tolerances for an electrosurgical jaw electrode, for example without limitation, +/−0.003″). In other embodiments, grasping surface  194  and/or first and/or second electrodes  190   a ,  190   b  may include one or more stop members (not shown) to maintain a predetermined minimum distance between jaw members  172 ,  174  when jaw members  172 ,  174  are in a closed position to effect a tissue seal. In some embodiments, first and/or second electrodes  190   a ,  190   b  may be recessed. 
         [0059]    Sealing electrodes  190   a ,  190   b  are configured to conduct electrosurgical energy to or from tissue. In some embodiments, electrodes  190   a ,  190   b  are electrically independent and selectively configurable to deliver positive (+), negative (−), ground, and/or floating potential to tissue, depending upon the desired procedure being performed. In other embodiments, electrodes  190   a ,  190   b  are electrically coupled and configured to deliver a similar electrical signal to tissue. Sealing electrodes  190   a ,  190   b  are coupled to the electrosurgical generator  14  and/or controller  4  via one or more conductors and/or cables (not shown). It should be understood that sealing electrodes  190   a ,  190   b  may perform electrosurgical procedures or functions other than sealing, and may operate collectively or independently in a bipolar, monopolar, return electrode, ground electrode, passive electrode, or any other mode. 
         [0060]    Turning to  FIGS. 4A-4C , jaw member  174  includes a jaw housing  187  having a grasping surface  184  ( FIG. 4B ). Jaw housing  187  and/or grasping surface  184  may be formed from a high-strength, heat-resistant, and electrically insulative material, such as, without limitation, ceramic, zirconia, sialons, and the like. In some embodiments, jaw housing  187  may be formed in full or in part from a metallic material. As described above, grasping surface  184  faces the grasping surface  194  of jaw member  172 . 
         [0061]    Jaw member  174  includes a number of electrodes. First and second return electrodes  180   a ,  180   b  are longitudinally disposed on grasping surface  184  of jaw member  174 , and a third return electrode  181  is longitudinally disposed centrally thereon, e.g., mid-way between first and second return electrodes  180   a ,  180   b . As described with respect to sealing electrodes  190   a ,  190   b  of jaw member  172 , in some embodiments, first, second, and third return electrodes  180   a ,  180   b , and  181  are embedded within grasping surface  184  such that the tissue-contacting surface of first, second, and third return electrodes  180   a ,  180   b , and  181  are substantially flush with grasping surface  184  while in yet other embodiments, first, second, and third return electrodes  180   a ,  180   b , and  181  are disposed on grasping surface  184 . Grasping surface  184  and/or first, second, and/or third return electrodes  180   a ,  180   b , and  181  may include one or more stop members (not shown) to maintain a predetermined minimum distance between jaw members  172 ,  174 , as previously described to effect a tissue seal. 
         [0062]    Return electrodes  180   a ,  180   b , and  181  are configured to conduct electrosurgical energy to or from tissue. In some embodiments, electrodes  180   a ,  180   b , and  181  are electrically independent and selectively configurable to deliver positive (+), negative (−), ground, and/or floating potential to tissue, depending upon the desired procedure being performed. In other embodiments, electrodes  180   a ,  180   b , and  181  are electrically coupled and configured to deliver a similar electrical signal to tissue. Electrodes  180   a ,  180   b , and  181  are coupled to electrosurgical generator  14  and/or controller  4 . It is to be understood that return electrodes  180   a ,  180   b , and  181  may perform electrosurgical procedures or functions other than acting as a return electrode, and may operate collectively or independently in a bipolar, monopolar, sealing, ground electrode, passive electrode, or any other mode. 
         [0063]    The central position of return electrode  181  of jaw member  174  corresponds to the longitudinal slot  173  when jaw member  172  and jaw member  174  oppose one another. In this manner, return electrode  181  is accessible, even if jaw members  172 ,  174  are in a closed position, to facilitate procedures performed in cooperation with another instrument, and, in particular, performed in cooperation with a second jaw assembly  150  under robotic control. 
         [0064]    In some embodiments, jaw member  174  includes a cutting electrode assembly  188  having a longitudinal electrode  186  that is positioned on a support ridge  185  disposed longitudinally on housing  187 . Cutting electrode assembly  188  is configured such that the electrode assembly  188  of a first jaw assembly  150  may be operably received within the longitudinal slot  173  of a second jaw assembly  150 ′ to deliver bipolar electrosurgical energy between the longitudinal electrode  186  of first jaw member  150  and third return electrode  181  of second jaw assembly  150 ′ ( FIGS. 5A and 5B ). In embodiments, cutting electrode assembly  188  is movable between a raised position where electrode  186  is positioned above the surface of housing  187  and shown generally in  FIG. 4C , and a lowered position where electrode  186  is positioned substantially flush with, or below, the surface of housing  187  ( FIG. 4D ). In the embodiment best shown in  FIGS. 2C and 4C , electrode assembly  188  protrudes from a top surface  191  of housing  187 , e.g., the opposite side of housing  187  from grasping surface  184 . 
         [0065]    In some embodiments, jaw member  174  includes a tip electrode assembly  189  having a tip electrode  183  that is positioned on an electrode support  182 . Electrode assembly  189  is configured to be operably received within the longitudinal slot  173  of a second jaw member  150 ′ to deliver bipolar electrosurgical energy between tip electrode assembly  189  of first jaw assembly  150  and electrode  181  of second jaw assembly  150 ′ ( FIGS. 5A and 5B ). In embodiments, tip electrode assembly  189  is movable between a first position where electrode  183  is positioned beyond a distal portion  164   b  of jaw housing  187  and shown generally in  FIG. 4C , and a second position where electrode  183  is positioned closer to, substantially flush with, or below, a distal portion  164   b  of jaw housing  187  ( FIG. 4E ). 
         [0066]    It should be understood that, while cutting electrode assembly  188  and tip electrode assembly  189  are configured to be operably received within the longitudinal slot  173 , it is envisioned that cutting electrode assembly  188  and tip electrode assembly  189  may be used in conjunction with any other instrument and/or may be used to treat tissue in monopolar mode. 
         [0067]    Turning now to  FIGS. 5A and 5B , an example method of performing a robotic electrosurgical procedure on patient tissue T in accordance with the present disclosure is illustrated. First and second robotic arms  2 ,  3  having respective end effectors  100 ,  100 ′ are utilized in the present example. As best seen in  FIG. 5A , using any indicated interventional robotic surgical technique, end effector  100 ′ is manipulated into a position whereby longitudinal slot  173 ′ of jaw assembly  150 ′ is positioned on one side of patient tissue T. End effector  100  is moved into position whereby cutting electrode assembly  188  of jaw assembly  150  is introduced into slot  173 ′ of jaw assembly  150 ′, thereby grasping patient tissue T therebetween. In some embodiments of the method, the motions positioning cutting electrode assembly  188 ′ within slot  173  may be choreographed by control device  4 . For example, a surgeon may position one or both end effectors  150 ,  150 ′ such that the targeted patient tissue T is positioned loosely therebetween. After confirming that patient tissue T is positioned correctly, and that no undesired object is between the two jaw assemblies  150 ,  150 ′, the surgeon may activate a “mating” function to complete the grasping operation. The mating function is executed by the robotic system, e.g., by control device  4 , which, in turn, causes jaw assemblies  150  and  150 ′ to draw together, thus clamping tissue T between electrode assembly  188  of jaw assembly  150 , and return electrode  181 ′ of jaw assembly  150 ′. Advantageously, the precise positioning capabilities of robotic arms  2 ,  3  enable accurate and repeatable control over tissue manipulation parameters during this phase of the procedure. For example, it may be desirable for a precise amount of tissue clamping force and/or a precise amount of tissue compression to be applied to tissue T. The gap distance between cutting electrode  186  and return electrode  181 ′ may also be precisely controlled to effect a tissue seal. In general, when tissue cutting is desired, the amount of clamping force and/or tissue compression may be greater than when, for example, vessel sealing is desired (which typically calls for less clamping force and/or compression). In some embodiments, the mating function may accept one or more user inputs from the surgeon specifying the amount of clamping force and/or tissue compression to be applied. In some embodiments, the gap distance between opposing sealing surfaces during tissue treatment may range from about 0.001 inches to about 0.006 inches. In some embodiments, closure force on opposing sealing surfaces during tissue treatment is in the range of about 3 kg/cm 2  to about 16 kg/cm 2 . 
         [0068]    When tissue T is properly positioned and clamped between jaw assemblies  150 ,  150 ′, electrosurgical energy is applied between cutting electrode  186  of jaw assembly  150 , and return electrode  181 ′ of jaw assembly  150 ′, which, in turn, causes the desired electrosurgical effect to tissue T (e.g., cutting, sealing, coagulating, desiccating, etc.) In some embodiments, at least one of a tissue temperature, tissue impedance, tissue hydration, or other tissue property may be sensed and utilized to control the delivery of electrosurgical energy. After the delivery of electrosurgical energy is completed, end effectors  100 ,  100 ′ are separated, thus releasing tissue T. In addition to the programmed control of mating, the application of electrosurgical energy and/or the release of tissue may be coordinated under control of control device  4 . 
         [0069]    With reference now to  FIG. 6 , another example method of performing a robotic electrosurgical procedure in accordance with the present disclosure is illustrated. In the present example, end effector  100  is manipulated into position at the surgical site. Jaw members  172  and  174  of jaw assembly  150  are moved to an open position. The targeted tissue T is positioned between jaw members  172  and  174  of jaw assembly  150 , and jaw members  174  and  172  are move to a closed position thereby grasping tissue T therebetween and exposing a strip of targeted tissue T within slot  173 . A second end effector  100 ′ is positioned at the surgical site and positioned such that tip electrode assembly  189 ′ of jaw member  174 ′ of jaw assembly  150 ′ is introduced into slot  173  of jaw assembly  150 . The introduction of tip electrode assembly  189 ′ into slot  173  may be choreographed by control device  4 , as described above, as may the clamping force and/or tissue compression between tip electrode  183 ′ and return electrode  181 . 
         [0070]    When tissue T is properly positioned and tip electrode assembly  189 ′ is introduced into slot  173 , electrosurgical energy is applied between tip electrode  183 ′ of jaw assembly  150 ′, and return electrode  181  of jaw assembly  150 . Concurrent with the application of electrosurgical energy, relative motion is imparted between jaw assembly  150  and jaw assembly  150 ′ such that tip electrode  183 ′ of jaw member  174 ′ moves along the exposed tissue held within slot  173  of jaw assembly  150 , which, in turn, causes the desired cutting, sealing, coagulating, desiccating, etc. to be performed to the exposed strip of targeted tissue T. After the delivery of electrosurgical energy is completed, end effectors  100 ,  100 ′ are separated, and jaw members  172 ,  174  of jaw assembly  150  are moved to an open position, thus releasing tissue T. In embodiments any one, some, or all of the steps of grasping tissue T, positioning tip electrode assembly  189 ′ within slot  173 , the application of electrosurgical energy, moving tip electrode  183 ′ within slot  173  to treat tissue, the separation of end effectors  100 ,  100 ′ and/or the opening of jaw members  172 ,  184  release of tissue may be coordinated by control device  4 . 
         [0071]    In yet another example embodiment best illustrated in  FIG. 7 , an end effector  200  includes a jaw assembly  250  having a first jaw member  262  and a second jaw member  264 . First and second jaw members  262 ,  264  include similar features to jaw members  172 ,  174  as described hereinabove. In the present embodiment, jaw member  264  includes a hook electrode assembly  265  disposed at a distal end  264   b  thereof. Hook electrode assembly  265  includes a body electrode  266  and an end electrode  267 . In some embodiments, body electrode  266  and end electrode  267  are electrically independent and selectively configurable to deliver positive (+), negative (−), ground, and/or floating potential to tissue, depending upon the desired procedure being performed. In other embodiments, body electrode  266  and end electrode  267  are electrically coupled and configured to deliver a similar electrical signal to tissue. Body electrode  266  and end electrode  267  are coupled to electrosurgical generator  14  and/or controller  4 . During use, hook electrode assembly  265  may be employed using any of the cooperative “two handed” electrosurgical techniques described herein, may be utilized to perform conventional electrosurgical procedures, and/or may be used for non-electrosurgical manipulation of tissue. Other forms of distal electrode assemblies are contemplated within the scope of the present disclosure, including without limitation, a scalpel, a spatula, a scissors, a needle, a probe, and/or a sensing device. 
         [0072]    The described example embodiments of the present disclosure are intended to be illustrative rather than limiting, and are not intended to represent every embodiment of the present disclosure. Further variations of the above-disclosed embodiments and other features and functions, or alternatives thereof, may be made or desirably combined into many other different systems or applications without departing from the spirit or scope of the disclosure as set forth in the following claims both literally and in equivalents recognized in law.