Patent Publication Number: US-2020281643-A1

Title: Reduced capacitively leakage current in electrosurgical instruments

Description:
CLAIM OF PRIORITY 
     This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 62/588,087, filed on Nov. 17, 2017, which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     Electrosurgery involves the use of electricity to buildup heat within biological tissue to cause thermal tissue damage resulting in incision, removal or sealing of the tissue through one or more of desiccation, coagulation, or vaporization, for example. Benefits include the ability to make precise cuts with limited blood loss. Electrosurgical devices are frequently used during surgical procedures to help prevent blood loss in hospital operating rooms or in outpatient procedures. High-frequency electrosurgery typically involves radio frequency (RF) alternating current (AC) that is converted to heat by resistance as it passes through the tissue. 
     SUMMARY 
     In one aspect, a surgical instrument includes a shaft that includes an elongated tube having distal and proximal end portions. The tube houses an electrical conductor that includes distal and portions and that extends between the proximal and distal end portions of the elongated tube. An end effector at the distal end portion of the elongated tube includes an electrode electrically coupled to the distal portion of the electrical conductor. A switch at the proximal end portion of the shaft is operatively disposed between the distal and proximal portions of the electrical conductor that is configured to electrically couple and decouple the distal and proximal portions of the electrical conductor. 
     In another aspect, a surgical system includes an electrosurgical instrument including proximal and distal end portions and including an electrode at the distal end portion. An electrosurgical signal generator provides an electrosurgical signal. A first electrical conductor extends between the electrosurgical instrument and the electrosurgical signal generator. A second electrical conductor extends between the proximal and distal end portions of the electrosurgical instrument and is electrically coupled to the electrode. A first switch electrically couples and decouples the electrosurgical signal to and from the second electrical conductor. A second switch to electrically couples and decouples the first and second electrical conductors. 
     In yet another aspect, a method selectably provides an electrosurgical signal at a surgical instrument end effector. In response to a command at a user interface control to energize an electrosurgical instrument, a first switch is closed to electrically provide an electrosurgical signal to a first electrical conductor and a second switch is closed to electrically couple the first electrical conductor to a second electrical conductor electrically coupled to an end effector. In response to no command at the user interface control to energize the electrosurgical instrument while a hovering gesture is detected at the user interface control, the first switch is opened to not provide the electrosurgical signal to the first electrical conductor and the second switch is closed to electrically couple the first electrical conductor to a second electrical conductor electrically coupled to an end effector. In response to a command at the user interface control to energize the electrosurgical instrument while no hovering gesture is detected at the user interface control, the first switch is opened to not provide the electrosurgical signal to the first electrical conductor and the second switch is opened to electrically decouple the first electrical conductor from the second electrical conductor electrically coupled to an end effector. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an illustrative plan view of a minimally invasive surgical system for performing a minimally invasive diagnostic or surgical procedure on a patient who is lying on an operating table. 
         FIG. 2  is an illustrative perspective view of the surgeon&#39;s console. 
         FIG. 3  is an illustrative perspective view of a patient-side cart of a minimally invasive surgical system. 
         FIG. 4  is an illustrative perspective view of a surgical instrument. 
         FIG. 5  is an illustrative schematic diagram showing a first bipolar surgical electrosurgical instrument and second monopolar surgical electrosurgical instrument that may be selectively coupled to receive high frequency signals from an electrosurgical generator unit in accordance with some embodiments. 
         FIG. 6  is an illustrative partially cut-away, cross-section drawing showing first and second cable isolation switches at the first bipolar electrosurgical instrument in accordance with some embodiments. 
         FIGS. 7A-7B  are illustrative top elevation views of a rotary disk switch embodiment of the first and second cable isolation switches of  FIGS. 5-6  in closed and open states, respectively, in accordance with some embodiments. 
         FIG. 7C  is an illustrative cross-section view along line  7 C- 7 C of  FIG. 7A  showing double wipe electrical switch contacts in accordance with some embodiments. 
         FIG. 8  is an illustrative perspective view of a motor pack to enclose multiple motors to controllably rotate individual rotary drive disks in accordance with some embodiments. 
         FIG. 9  is an illustrative drawing representing a lead screw embodiment of a cable isolation switch. 
         FIG. 10  is an illustrative drawing representing a cam action embodiment of a first cable isolation switch. 
         FIG. 11  is an illustrative drawing representing user interface controls and a sensor device disposed to sense user proximity in accordance with some embodiments. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Surgical System 
       FIG. 1  is an illustrative plan view of a minimally invasive surgical system  10  for performing a minimally invasive diagnostic or surgical procedure on a patient  12  who is lying on an operating table  14 . The system includes a surgeon&#39;s console  16  for use by a surgeon  18  during the procedure. One or more assistants  20  may also participate in the procedure. The minimally invasive surgical system  10  further includes one or more patient-side cart  22  and an electronics cart  24 . The patient-side cart  22  can manipulate at least one surgical instrument  26  through a minimally invasive incision in the body of the patient  12  while the surgeon  18  views the surgical site through the surgeon&#39;s console  16 . An image of the surgical site can be obtained by an endoscope  28 , such as a stereoscopic endoscope, which may be manipulated by the patient-side cart  22  to orient the endoscope  28 . Computer processors located on the electronics cart  24  may be used to process the images of the surgical site for subsequent display to the surgeon  18  through the surgeon&#39;s console  16 . In some embodiments, stereoscopic images may be captured, which allow the perception of depth during a surgical procedure. The number of surgical instruments  26  used at one time will generally depend on the diagnostic or surgical procedure and the space constraints within the operative site among other factors. If it is necessary to change one or more of the surgical instruments  26  being used during a procedure, an assistant  20  may remove the surgical instrument  26  from the patient-side cart  22 , and replace it with another surgical instrument  26  from a tray  30  in the operating room. 
       FIG. 2  is a perspective view of the surgeon&#39;s console  16 . The surgeon&#39;s console  16  includes a viewer display  31  that includes a left eye display  32  and a right eye display  34  for presenting the surgeon  18  with a coordinated stereoscopic view of the surgical site that enables depth perception. The console  16  further includes one or more hand-operated user interface control inputs  36  to receive the larger-scale hand control movements and includes one or more foot pedal user interface control inputs  37 . The foot pedal user interface control inputs  37  may receive user commands to actuate an electrosurgical instrument. For example, a user may press down upon a foot pedal to indicate a command to energize an electrosurgical instrument, and a user may release a foot pedal to indicate a command to de-energize an electrosurgical instrument. One or more surgical instruments installed for use on the patient-side cart  22  move in smaller-scale distances in response to surgeon  18 &#39;s larger-scale manipulation of the one or more control inputs  36 . The control inputs  36  may provide the same mechanical degrees of freedom as their associated surgical instruments  26  to provide the surgeon  18  with telepresence, e.g., the perception that the control inputs  36  are integral with the instruments  26  so that the surgeon has a strong sense of directly controlling the instruments  26 . To this end, position, force, and tactile feedback sensors (not shown) may be employed to transmit position, force, and tactile sensations from the surgical instruments  26  back to the surgeon&#39;s hands through the control inputs  36 , subject to communication delay constraints. 
       FIG. 3  is a perspective view of a patient-side cart  22  of a minimally invasive surgical system  10 , in accordance with embodiments. The patient-side cart  22  includes four mechanical support arms  72 . A surgical instrument manipulator  73 , which includes motors to control instrument motion, is mounted at the end of each support arm assembly  72 . Additionally, each support arm  72  can optionally include one or more setup joints (e.g., unpowered and/or lockable) that are used to position the attached surgical instrument manipulator  73  in relation to the patient for surgery. While the patient-side cart  22  is shown as including four surgical instrument manipulators  73 , more or fewer surgical instrument manipulators  73  may be used. A surgical system will generally include a vision system that typically includes an endoscopic camera instrument  28  for capturing video images and one or more video displays for displaying the captured video images. User inputs provided at the control console  16  to control either the instrument as a whole or the instrument&#39;s components are such that the input provided by a surgeon or other medical person to the control input (a “master” command) is translated into a corresponding action by the surgical instrument (a “slave” response). 
       FIG. 4  is a perspective view of a surgical instrument  26 , which includes an elongated hollow tubular shaft  410  having a centerline longitudinal axis  411 , a distal (first) end portion  450  for insertion into a patient&#39;s body cavity and proximal (second) end portion  456  coupled adjacent an end effector actuator mechanism  440  disposed at a proximal end of the instrument  26 , which includes multiple mechanical actuators  445 ,  447  (shown with dashed lines) that may include one or more pulleys, guides, anchors, capstans, levers, linear slides or anchors, for example, cooperatively coupled to exert force upon mechanical wire cables that extend within the shaft  410  and that are coupled to impart motion to the end effector  454  such as opening or closing of jaws and (x, y) wrist motion of a wrist. The surgical instrument  26  is used to carry out surgical or diagnostic procedures. The distal portion  450  of the surgical instrument  26  can provide any of a variety of end effectors  454 , such as the forceps shown, a needle driver, a cautery device, a cutting tool, an imaging device (e.g., an endoscope or ultrasound probe), or the like. The surgical end effector  454  can include a functional mechanical degree of freedom, such as jaws that open or close, or a knife that translates along a path or a wrist that may move in x and y directions. In the embodiment shown, the end effector  454  is coupled to the elongated hollow shaft  410  by a wrist  452  that allows the end effector to be oriented relative to the elongate tube centerline axis  411 . The end effector actuator  440  controls movement of the end effector at its distal portion. 
     Electrosurgical Instruments 
       FIG. 5  is an illustrative schematic diagram showing a first bipolar surgical electrosurgical instrument  26 - 1  and second monopolar surgical electrosurgical instrument  26 - 2  that may be selectively coupled to receive electrosurgical signals from an electrosurgical generator unit (ESU)  502  in accordance with some embodiments. An electrosurgical signal typically is a high frequency signal (HF) in a radio frequency range (RF) that has a voltage level suitable to achieve a desired surgical effect such as desiccation, coagulation, or vaporization, for example. The voltage level of an electrosurgical signal may be selected according to the desired surgical effect. The first electrosurgical instrument (ESI)  26 - 1  includes a first end effector  454 - 1  that includes a first jaw member  520  including a first electrode  504  and a second jaw member  522  that includes a second electrode  506 . The second ESI  26 - 2  includes a second end effector  454 - 2  that includes a single electrode, a third electrode  508 . A first conductor cable  510  extends between the ESU  502  and the first and second electrodes  504 ,  506  of the first ESI  26 - 1 . A second conductor cable  512  extends between the ESU  502  and the third electrode  508  of the second ESI  26 - 2 . A third conductor cable  514  extends between the ESU  502  and a return conductor pad  516  that may be placed in contact with patient tissue  518  to act as a return path for current provided on the third electrode  508 . Commonly assigned U.S. Provisional Patent Application, Ser. No. 62/513,287, filed May 31, 2017, entitled Electrosurgical Output Stage with Integrated DC Regulator, describes an ESU  502  in accordance with some embodiments, and is expressly incorporated herein in its entirety by this reference. 
     The first end effector  454 - 1  of the first bipolar ESI  26 - 1  includes an articulated jaw that includes first and second jaw members  520 ,  522  that articulate relative to one another about a pivot axis  524 . At least one of the first and second jaw members  520 ,  522  is mounted to rotatably pivot about the pivot axis  524  between an open position in which the first and second jaws  520 ,  522  are spaced apart from each other and a closed position for grasping biological tissue  518  between them. The first and second electrodes  504 ,  506  are mounted upon the jaw members  520 ,  522  to electrically contact biological tissue  518  grasped between the first and second jaw members  520 ,  522 . During normal operation, while the jaw members  520 ,  522  grip tissue between them, the ESU  502  may impart a high frequency electrosurgical signal between the first and second electrodes  504 ,  506  to cause electrical current to flow through a first tissue portion  518 - 1  grasped between the jaw members  520 ,  522  to impart heat to the first tissue portion  518 - 1  to thereby impart an electrosurgical surgical effect such as desiccation, coagulation, or vaporization, for example. 
     The second end effector  454 - 2  of the second monopolar ESI  26 - 2  includes the single third electrode  508  that may be placed in contact with a patient&#39;s biological tissue  518 . During normal operation, the ESU  502  may impart a high frequency electrosurgical signal between the third electrode  508  and the return conductor pad  516  to cause electrical current to flow through a second tissue portion  518 - 2  disposed between the third electrode  508  and the return conductor pad  516  to cause electrical current to flow through the second tissue portion  518 - 2  to impart to the second tissue portion  518 - 2  an electrosurgical effect. The return conductor pad  516  may have a surface area that is large enough so that patient tissue in physical contact with the pad has a large enough surface area so that return current to the ESU  502  spreads across a wide enough patient tissue area  518  to limit the current density sufficiently to avoid tissue burns or other trauma due to the return current, for example. 
     In some embodiments, the bipolar first ESI  26 - 1  uses lower voltage, and therefore lower energy, than the monopolar second ESI  26 - 2 . Because of the lower energy level, bipolar ESI  26 - 1  may have a more limited ability to cut and coagulate large bleeding areas, and is more ideally used for those procedures where the first biological tissue portion  26 - 1  can be easily grabbed on both sides by the jaw members  520 ,  522  containing the first and second electrodes  504 ,  506 . Thus, in bipolar surgery, the electrosurgical current in the patient is restricted to just the tissue between the jaw electrodes  504 ,  506 , which may provide better control over the area being targeted, and help prevent damage to other sensitive tissues. In some embodiments, a typical bipolar ESI may operate at a voltage in a range of approximately 60 Vp-500 Vp, and a typical monopolar second ESI may operate at a voltage in a range of approximately 300 Vp-3,000 Vp, for example. 
     The first and second conductor cables  510 ,  512  span a distance between the ESU  502  and the respective first and second ESIs  26 - 1 ,  26 - 2 . The first conductor cable  510  includes a cable outer sheath  510 S, which may include insulating material that encloses first and second conductor cords  510 - 1 ,  510 - 2  that extend within it. The second conductor cable  512  includes a cable outer sheath  512 S, which may include insulating material that encloses a third conductor cord  512 - 1  that extends within it. Proximal end portions of the respective first and second conductor cables  510 P,  512 P and of their respective conductor cords are disposed at the ESU  502 . Distal end portions of the respective first and second conductor cables  510 D,  512 D and of their respective conductor cords are respectively disposed at the first and second ESIs  26 - 1 ,  26 - 2 . A proximal end portion of the third (return) cable  514 P is disposed at the ESU  502 , and a distal end portion of the third cable  514 D, secured to the return pad  516 , may be disposed at patient&#39;s anatomical tissue  518 . In some embodiments, the length of the first and second cables  510 ,  512  may be more than a meter, and therefore, the electrical current path between the proximal end portions  510 P,  512 P and distal end portions  510 D,  512 D of the first and second conductor cables  510 ,  512  may span a distance of more than a meter. 
     The ESU  502  includes a first transformer circuit  540  to selectably couple an electrosurgical signal between the first and second conductor cords  510 - 1 ,  510 - 2  at the proximal end portion  510 P of the of the first conductor cable  510 . More particularly, a first pair of transformer switches  542 ,  544  at the ESU  502  are configured to controllably electrically couple and decouple respective first and second terminals  546 ,  548  of the first transformer  540  to and from the respective first and second conductor cords  510 - 1 ,  510 - 2  at the proximal end portion  510 P of the first cable  510 . The ESU  502  includes a second transformer circuit  550  to selectably couple an electrosurgical signal between the third conductor cord  512 - 1  at the proximal end portion  512 P of the second cable  512  and the third (return) conductor cable  514 . More specifically, a second pair of transformer switches  552 ,  554  at the ESU  502  are configured to controllably electrically couple and decouple the first and second terminals  556 ,  558  of the second transformer  550 , respectively, to and from the third conductor cord  512 - 1  at the proximal end portion  512 P of the second cable  512  and the third (return) conductor cable  516 . 
     First and second electrical isolation switches  202 ,  204  are configured to controllably electrically couple and decouple the distal end portion  510 D of the first cable  510  to and from first and second instrument conductors  550 - 1 ,  550 - 2  coupled to the first and second electrodes  504 ,  506  of the first bipolar ESI  26 - 1 . More particularly, a first instrument conductor  550  includes a proximal portion  550 - 1 P and a distal portion  550 - 1 D, and a second instrument conductor  550 - 2  includes a proximal portion  550 - 2 P and a distal portion  550 - 2 D. The proximal portion  550 - 1 P of the first instrument conductor  550 - 1  is electrically coupled to the first conductor cord  510 - 1 , and the distal portion of the  510 - 1 D of the first instrument conductor  550 - 1  is electrically coupled to the first electrode  504 . Similarly, the distal portion  550 - 2 D of the second instrument conductor  550 - 2  is electrically coupled to the second conductor cord  510 - 2 , and the distal portion of the  510 - 2 D of the second instrument conductor  550 - 2  is electrically coupled to the second electrode  506 . The first electrical isolation switch  202  is operatively disposed to selectably couple and decouple the proximal and distal portions  550 - 1 P,  550 - 1 D of the first instrument conductor  550 - 1 . Similarly, the second electrical isolation switch  204  is operatively disposed to selectably couple and decouple the proximal and distal portions  550 - 2 P,  550 - 2 D of the second instrument conductor  550 - 2 . The first and second electrical isolation switches  202 ,  204  may be opened to electrically isolate the first and second electrodes  504 ,  506  from the first and second conductor cords  510 - 1 ,  510 - 2 . The first and second electrical isolation switches  202 ,  204  may be closed to electrically couple the first and second electrodes  504 ,  506  with the respective first and second conductor cords  510 - 1 ,  510 - 2 . 
     In some embodiments, the first and second electrical isolation switches  202 ,  204  may be disposed within the end effector actuator mechanism  440 , which includes first and second mechanical actuators  445 ,  447  at a distal end portion of the first ESI  26 - 1 . The distal portions  550 - 1 D,  550 - 2 D of the first and second instrument conductors  550 - 1 ,  550 - 2  extend within a hollow tubular shaft  410  between the isolation switches at the proximal end portion  456  shaft  410  and the first end effector  454 - 1  at a distal end of the shaft  410 . Moreover, mechanical wire cables  560 - 1 ,  560 - 2  extend within the hollow tubular shaft  410  between the first and second mechanical actuators  445 ,  447  and the end effector  454 - 1 . In some embodiments, mechanical actuators rather than electronic actuators are used within the end effector actuator mechanism  440  so as to reduce potential electrical interference with other medical devices such as a patient&#39;s pacemaker, for example. 
       FIG. 6  is an illustrative partially cut-away drawing showing certain details of a portion of the first cable  510 . The first cable  510  includes a protective outer sheath  510 S, which may be insulating. The first and second conductor cords  510 - 1 ,  510 - 2  are disposed within the protective sheath  510 S. The first conductive cord  510 - 1  includes an insulative outer layer  510 - 11  and a conductive inner core  510 - 1 C. Similarly, the second conductive cord  510 - 2  includes an insulative outer layer  510 - 21  and a conductive inner core  510 - 2 C. Thus, the first isolation switch  202  controllably couples and decouples the distal portion of the conductive inner core  510 - 1 C to and from the first electrode  504  and the second isolation switch  204  controllably couples and decouples the distal portion of the conductive inner core  510 - 2 C to and from the second electrode  506 . 
     Referring again to  FIG. 5 , during normal operation, during activation of the first bipolar ESI  26 - 1 , the first pair of transformer switches  542 ,  544  are closed to electrically couple the first and second conductor cords  510 - 1 ,  510 - 2  at the proximal end portion  510 P of the first cable  510  to the first transformer  540 , and the first and second cable isolation switches  202 ,  204  are closed to electrically couple the distal end portions of the first and second conductor cords  510 - 1 D,  510 - 2 D to the respective first and second electrodes  504 ,  506  of the respective first and second jaw members  520 ,  522 . An electrosurgical signal is thereby provided between the first and second electrodes  504 ,  506 . Also during normal operation, during activation of the first bipolar ESI  26 - 1 , the second pair of transformer switches  552 ,  554  are open to electrically decouple the proximal end portion  512 P of the second cable  512  and the third (return) cable  514  from the second transformer  550 . 
     Still referring to  FIG. 5 , conversely, during normal operation, during activation of the second monopolar ESI  26 - 2 , the second pair of transformer switches  552 ,  554  are closed to electrically couple the proximal end portion  512 P of the second cable  512  and the third (return) conductor cable  514  to the second transformer  550 . Also, during activation of the second monopolar ESI  26 - 2 , the first pair of transformer switches  542 ,  544  are opened to electrically decouple the proximal end portion  510 P of the first cable  510  from the first transformer  540 , and the first and second cable isolation switches  202 ,  204  are opened to electrically decouple the distal end portions of the first and second conductor cords  510 - 1 D,  510 - 2 D, at the distal end portion  510 D of the first cable  510 , from the first and second electrodes  504 ,  506  of the first end effector  454 - 1 . 
     The first and second electrical isolation switches  202 ,  204  help protect a patient from harm. The first and second cable isolation switches  202 ,  204  are switched to an open state during activation of the second monopolar ESI  26 - 2 , to electrically isolate the proximal portions  550 - 1 P,  550 - 2 P of the first and second instrument conductors  550 - 1 ,  550 - 2  and the respective first and second electrodes  540 ,  506  electrically coupled thereto, from the first and second conductor cords  510 - 1 ,  510 - 2  to block leakage current from flowing within the first and second electrodes  202 ,  204 . More particularly, without isolation, a leakage current to the first cable  510  may result from capacitive coupling, C G , of the first cable  510  to ground and/or from capacitive coupling, C C1/C2 , between the first and second cables  510 ,  512 , for example. That is, during operation of the monopolar ESI  26 - 2 , in the absence of isolation provided by the first and second switches  202 ,  204 , a portion of the electrosurgical current flow between the single third electrode  508  and the return pad  516  of the second monopolar ESI  26 - 2  may instead leak through patient tissue  518  to the first and/or second electrodes  504 ,  506  of the first bipolar ESI  26 - 1  due to such capacitive coupling C G  and/or C C1/C2 . Such leakage current flow through patient tissue  518  may result in unintended thermal effects such as tissue burn or internal organ damage. Thus, the first and second cable isolation switches  202 ,  204  help to mitigate or prevent stray leakage current caused by capacitive coupling from flowing through patient tissue  518 , which otherwise could result in harm to a patient. Moreover, capacitive coupling such as C G  and/or C C1/C2  may occur due to a surgical tool (not shown), such as a cautery device or a surgical stapler that contacts a patient&#39;s anatomy, and that is energized by lower frequency signals provided on a conductive cable. In other words, a risk of patient harm can arise due to leakage current arising from capacitive coupling even if the second tool is not an electrosurgical instrument energized with a high frequency signal. 
     Isolation Switches 
       FIGS. 7A-7B  are illustrative top elevation views of a mechanical rotary disk switch embodiment  700  of the first and second cable isolation switches  202 ,  204  of  FIGS. 5-6  in closed and open states, respectively, in accordance with some embodiments.  FIG. 7C  is an illustrative cross-section view along line  7 C- 7 C of  FIG. 7A  showing double wipe electrical switch contacts  702  in accordance with some embodiments. The rotary disk switch  700  is mounted for rotation about a disk axis  704 . The disk switch  700  has alternating top and bottom conductive surface strips  706 - 1 ,  706 - 2  and non-conductive surface strips  708 - 1 ,  708 - 2  spaced evenly about its perimeter. Respective first and second conductive surface strips  706 - 1 ,  706 - 2  are disposed opposite each other at perimeter regions of the disk switch  700  between the first and second non-conductive surface strips  708 - 1 ,  708 - 2 . Respective first and second non-conductive surface strips  708 - 1 ,  708 - 2  are disposed opposite each other at perimeter regions of the disk switch  700  between the first and second conductive surface strips  706 - 1 ,  706 - 2 . 
     In some embodiments, the first conductive surface strip  706 - 1  and the first non-conductive strip  706 - 1  of rotary disk switch  700  implements the first cable isolation switch  202 . The first isolation switch includes first and second terminals  710 ,  712  disposed at fixed positions to physically contact top and bottom surfaces of the disk switch perimeter. The first terminal  710  is electrically coupled to the first electrode  504  and the second terminal  712  is electrically coupled to the distal end portion of the first conductor cord  510 - 1 D. In some embodiments, the second conductive surface strip  706 - 2  and the second non-conductive surface strip  708 - 2  of rotary disk switch  700  implements the second cable isolation switch  204 . The first isolation switch includes third and fourth terminals  714 ,  716  disposed at fixed positions to physically contact top and bottom surfaces of the disk switch perimeter. The third terminal  714  is electrically coupled to the second electrode  506  and the fourth terminal  716  is electrically coupled to the distal end portion of the second conductor cord  510 - 2 D. 
     The disk switch  700  rotates between a first switch state shown in  FIG. 7A  and a second switch state shown in  FIG. 7B . In the first switch state shown in  FIG. 7A , the disk switch  700  is rotated such that top and bottom of the first conductive surface  706 - 1  electrically contact both the first and second terminals  710 ,  712  to electrically couple the first electrode  504  with the distal portion of the first conductor cord  510 - 1 D, and the top and bottom of the second conductive surface  706 - 2  electrically contact both the third and fourth terminals  714 ,  716  to electrically couple the second electrode  506  with the distal end portion of the second conductor cord  510 - 2 D. In the second switch state shown in  FIG. 7B , the disk switch  700  is rotated such that top and bottom of the first non-conductive surface  708 - 1  electrically contact both the first and second terminals  710 ,  712  to electrically decouple the first electrode  504  from the distal end portion of the first conductor cord  510 - 1 D, and the top and bottom of the second non-conductive surface  708 - 2  electrically contact both the third and fourth terminals  714 ,  716  to electrically decouple the second electrode  506  from the distal end portion of the second conductor cord  510 - 2 D. Thus, in the second switch state, the first and second cable isolation switches  202 ,  204  are opened to electrically decouple the first cable  510  from the first bipolar ESI  26 - 1 . Moreover, as the disk switch  700  rotates between the first and second switch states, the double wipe electrical contact action of the first through fourth terminals  710 - 716  helps to ensure good electrical contact by wiping away contaminants such as oxide build-up, for example. 
       FIG. 8  is an illustrative perspective view of a motor pack  800  to enclose multiple motors (not shown) to controllably rotate individual mechanical rotary drive disks  802  in accordance with some embodiments. One or more of the rotary drive disks  802  may be configured to impart rotational force to actuate the disk switch of  FIGS. 7A-7C . The rotary drive disks  802  also may be coupled to impart drive forces to the first and second end effector actuators  445 ,  447  within the mechanism  440  at the proximal end portion  456  of the shaft  410 , to impart forces to wire cables  460 - 1 ,  460 - 2  that extend internally along the length of the shaft  410 , to impart motion to an end effector  454  at a distal end portion  450  of the shaft  410 . An adapter (not shown) may be disposed between the rotary drive disks  802  of the motor pack  800  and the end effector actuator mechanism  440  to adapt motor-driven rotary disk drive forces to wire cable actuation forces. In some embodiments, one of the rotary disk drives may be configured to selectably rotate the disk switch  700  of  FIGS. 7A-7C . 
       FIG. 9  is an illustrative drawing representing a mechanical lead screw embodiment  900  of a first cable isolation switch  202 . A lead screw  902  is threaded through a nut body  904 . The nut body  904  is configured such that rotation of the lead screw  902  causes vertical motion of the nut body  904  along the length of the lead screw  902 . A cantilever beam  906  formed of an electrically conductive material such as metal, extends from the nut body  904 . First and second electrical contacts  910 ,  912  upstand from the cantilever beam  906 . The first electrical contact  910  is vertically aligned with a third electrical contact  914  that is electrically coupled to the first electrode  504 . The second electrical contact  912  is vertically aligned with a fourth electrical contact  916  that is electrically coupled to the distal end portion of the first conductor cord  510 - 1 D. 
     In a first switch state (not shown), the first  910  contact electrically contacts the third contact  914  and the second contact  912  electrically contacts the fourth contact  916  to close the first switch. In a second switch state shown in  FIG. 9 , the first  910  contact is electrically isolated from the third contact  914  and the second contact  912  is electrically isolated from the fourth contact  916  to open the first switch. It will be appreciated that a similar lead screw arrangement (not shown) may be provided to implement the second cable isolation switch  206 . 
       FIG. 10  is an illustrative drawing representing a mechanical cam action switch embodiment  1000  of a first cable isolation switch  202 . A first electrical contact  1010  electrically coupled to the first electrode  504  is disposed at a fixed location. A second electrical contact  1012  electrically coupled to the distal end of the first conductor cord  510 - 1 D is disposed at a first end portion of an armature  1020  mounted to a pivot axis  1022 . A bias spring  1024  is secured to a second end portion of the armature  1020  to urge the armature  1020  to pivot about the pivot axis  1022  to space apart the first and second electrical contacts  1010 ,  1012 . A rotatable cam  1016  is configured to be rotatable to a first switch state in which a cam surface imparts a force to a cam follower linkage  1028  to the armature  1020  to overcome the spring force and urge the first and second electrical contacts  1010 ,  1012  into electrical contact to close the first switch  202 . The rotatable cam is configured to be rotatable to a second switch state in which a force imparted by cam surface to the cam follower linkage  1028  does not overcome the spring force, which urges the first and second electrical contacts  1010 ,  1012  apart so that they do not make electrical contact and the first switch  202  is opened. It will be appreciated that a similar cam action arrangement (not shown) may be provided to implement the second cable isolation switch  204 . 
       FIG. 11  is an illustrative drawing representing user interface controls and a sensor device disposed to sense proximity of a user to the respective UI controls. More specifically,  FIG. 11  shows left and right foot pedal user interface controls  37 L,  37 R and a sensor device  902  disposed to sense proximity of a user&#39;s left and/or right foot  1104 L,  1104 R to the respective foot pedals. One or more of the computer processors disposed at the electronics cart  24  is configured to cause the electrical isolation switches  202 ,  204  to close to electrically couple the first and second electrodes  504 ,  506  to the first and second conductor cords  510 - 1 ,  510 - 2  in response to the sensor device  1102  sensing a user hovering gesture defined as a user&#39;s foot reaching to within a prescribed hovering distance from the foot pedals  1106 L,  1104 R, indicated by dashed lines  1106 L,  1106 R. It will that an operator of a surgical instrument may be quite sensitive and the moment when the electrosurgical signal is provided. Mechanical switching may be relatively slow as compared with electronic switching. Commencing closing of the isolation switches  202 ,  204  in response to a hovering gesture may result in starting the closure of these slower switches sooner so as to reduce the delay perceived by an operator. Although illustrative embodiments have been shown and described, a wide range of modification, change and substitution is contemplated in the foregoing disclosure and in some instances, some features of the embodiments may be employed without a corresponding use of other features. For example, an electrical isolation switch alternatively, may be provided for use with a monopolar electrosurgical instrument. One of ordinary skill in the art would recognize many variations, alternatives, and modifications. Thus, the scope of the disclosure should be limited only by the following claims, and it is appropriate that the claims be construed broadly and in a manner consistent with the scope of the embodiments disclosed herein. The above description is presented to enable any person skilled in the art to create and use a system and method to reduce capacitively coupled leakage current in electrosurgical instruments. Various modifications to the embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments and applications without departing from the scope of the invention. In the preceding description, numerous details are set forth for the purpose of explanation. However, one of ordinary skill in the art will realize that the invention might be practiced without the use of these specific details. In other instances, well-known processes are shown in block diagram form in order not to obscure the description of the invention with unnecessary detail. Identical reference numerals may be used to represent different views of the same or similar item in different drawings. Thus, the foregoing description and drawings of embodiments in accordance with the present invention are merely illustrative of the principles of the invention. Therefore, it will be understood that various modifications can be made to the embodiments by those skilled in the art without departing from the scope of the invention, which is defined in the appended claims.