Patent Publication Number: US-2013245356-A1

Title: Hand held surgical device for manipulating an internal magnet assembly within a patient

Description:
BACKGROUND 
     i. Field of the Invention 
     The present application relates to methods and devices for minimally invasive therapeutic, diagnostic, or surgical procedures and, more particularly, to magnetic guidance systems for use in minimally invasive procedures. 
     ii. Description of the Related Art 
     In a minimally invasive therapeutic, diagnostic, and surgical procedures, such as laparoscopic surgery, a surgeon may place one or more small ports into a patient&#39;s abdomen to gain access into the abdominal cavity of the patient. A surgeon may use, for example, a port for insufflating the abdominal cavity to create space, a port for introducing a laparoscope for viewing, and a number of other ports for introducing surgical instruments for operating on tissue. Other minimally invasive procedures include natural orifice transluminal endoscopic surgery (NOTES) wherein surgical instruments and viewing devices are introduced into a patient&#39;s body through, for example, the mouth, nose, or rectum. The benefits of minimally invasive procedures compared to open surgery procedures for treating certain types of wounds and diseases are now well-known to include faster recovery time and less pain for the patient, better outcomes, and lower overall costs. 
     Magnetic anchoring and guidance systems (MAGS) have been developed for use in minimally invasive procedures. MAGS include an internal device attached in some manner to a surgical instrument, endoscope, laparoscope or other camera or viewing device, and an external hand held device for controlling the movement of the internal device. Each of the external and internal devices has magnets which are magnetically coupled to each other across, for example, a patient&#39;s abdominal wall. In the current systems, the external magnet may be adjusted by varying the height of the external magnet. 
     The foregoing discussion is intended only to illustrate various aspects of the related art in the field of the invention at the time, and should not be taken as a disavowal of claim scope. 
     SUMMARY 
     A device is described herein for manipulating a magnetic coupling force across tissue based on the monitored coupling force generated between externally and internally disposed magnets. In one embodiment, the device includes a magnetic field source assembly that comprises a first magnetic field source for providing a magnetic field across tissue. The first magnetic field provides a magnetic coupling force between the first magnetic field source and an object that provides or is associated with a second magnetic field. The device also includes an actuation assembly operatively connected to the magnetic field force assembly for adjusting the movement of the first magnetic field source, and a magnetic coupling force monitor. 
     In certain embodiments, the device for manipulating a magnetic coupling force across tissue comprises a magnetic field source assembly comprising a first magnetic field source positioned in use on one side of tissue and for providing, in use, a magnetic field across the tissue. The first magnetic field source provides a magnetic coupling force between the first magnetic field source and an object positioned, in use, on the opposing side of the tissue which provides, in use, a second magnetic field source. The first magnetic field source comprises at least one fixed magnet and at least one rotatable magnet. The device also includes an actuation assembly operatively connected to the magnetic field force assembly for rotating the rotatable magnet to adjust magnetic flux generated by the first magnetic field source. The device further includes a magnetic force monitoring system for sensing changes in the magnetic coupling force. The monitoring system is in operative communication with the actuation assembly for controlling the actuation thereof in response to the changes in the magnetic coupling force. 
     In various embodiments, the magnetic field source assembly may further include a magnet suspension member, and the fixed magnet may be operatively suspended from the suspension member. The fixed magnet may define a cavity therein for receiving the rotatable magnet. The actuation assembly may include a driver for effecting rotation of the rotatable magnet, a rack and pinion gear set for driving the driver, and an actuator to actuate the rack and pinion gear set. 
     The actuator may actuate the rack and pinion gear set, for example, in response to signals from the magnetic force monitoring system. In various embodiments, the actuator may be a motor having a reciprocating arm operatively connected to the rack of the rack and pinion gear set such that reciprocation of the arm effects reciprocal linear motion of the rack. In various embodiments, the pinion gear may be operatively connected to the rack such that the linear motion of the rack is translated into rotational movement of the pinion gear, and the driver may be a drive shaft operatively connected to the pinion gear such that rotation of the pinion gear effects rotation of the drive shaft. The motion of the reciprocating arm may be in stepped increments or may be continuous. 
     The magnetic coupling force monitor may comprise a sensor plate, a sensor positioned adjacent the sensor plate for measuring changes in the magnetic coupling force between the first magnetic field source and the second magnetic field source and for transmitting signals representative of the measured change in the magnetic coupling force, a control unit for receiving the signals from the sensor, and a processor in communication with the control unit for converting the received signals to output signals for signaling the actuator to adjust the direction of rotation of the rotatable magnet until a predetermined magnetic coupling force is measured by the sensor. 
     The device may also include in certain embodiments, a suspension member attached to the at least one fixed magnet, and a support member positioned proximally to the suspension member for housing the rack and pinion gear set and a proximal portion of the driver. The support member may have a surface for supporting the sensor. The sensor plate may be positioned proximally to the support member in a facing relationship to the sensor. In various embodiments, at least a portion of the sensor plate is in contact with the sensor. 
     A plurality of elevation members may be provided. Each elevation member may be slidingly connected at a proximal end thereof to the sensor plate and at a distal end thereof to the suspension member. Each elevation member may have a smooth proximal portion for sliding engagement with the support member and the sensor plate for allowing the sensor plate to move between a rest position and positions of applied force relative to the sensor. In various embodiments, an increased magnetic coupling force operatively exerts a distally directed force on the sensor plate moving the sensor plate from the rest position to an applied force position relative to the sensor, wherein the change in the force exerted on the sensor is communicated to the actuator. 
     The sensor and the actuator may be in communication with a control unit for matching the sensed change in force exerted on the sensor to a predetermined desirable force within a range of acceptable forces. In such embodiments, the control unit communicates commands to the actuator to adjust the rotation of the rotatable magnet, which adjusts the magnetic flux generated by the first magnetic field source if the sensed force exerted on the sensor does not match the predetermined desirable force. 
     In certain aspects, the device for manipulating a magnetic coupling force across tissue may comprise a suspension block and a magnetic field source assembly comprising at least one magnet fixedly suspended from the suspension block and at least one rotatable magnet positioned within a cavity defined within the fixed magnet. In this aspect, the device further includes a support block, an actuation assembly and a magnetic force monitoring system. The actuation assembly comprises a driver for effecting rotation of the rotatable magnet to adjust magnetic flux generated by the magnetic field source assembly, a rack and pinion gear set housed in the support block for driving the driver, and an actuator for actuating the rack and pinion gear set. The magnetic force monitoring system comprises a sensor supported by the support block and a sensor plate. The sensor plate may be positioned proximally in a facing relationship relative to the sensor such that at least a portion of the sensor plate is in contact with the sensor. In this aspect, the device includes a plurality of elevation members, each of which is slidingly connected at a proximal end thereof to the sensor plate and at a distal end thereof to the suspension member. Each elevation member in this embodiment has a smooth proximal portion for sliding engagement with the support member and the sensor plate for allowing the sensor plate to move between a rest position and positions of applied force relative to the sensor. The sensor may be calibrated to sense any change in the force exerted on the sensor by the sensor plate. A communication circuit from the sensor to the actuator controls the actuation of the actuator in response to the monitored changes in force. 
    
    
     
       FIGURES 
       Various features of the embodiments described herein are set forth with particularity in the appended claims. The various embodiments, however, both as to organization and methods of operation, together with advantages thereof, may be understood in accordance with the following description taken in conjunction with the accompanying drawings as follows. 
         FIG. 1A  is a perspective view of an embodiment of a hand held surgical manipulation device and  FIG. 1B  shows the manipulation device of  FIG. 1A  positioned on the exterior of a patient&#39;s torso magnetically positioning a surgical tool placed inside the patient opposite the external manipulation device. 
         FIG. 2  is a rear view of an embodiment of the device of  FIG. 1  with the housing and top cover removed. 
         FIG. 3 . is a perspective view of the bottom of an embodiment of the device of  FIG. 2 . 
         FIG. 4  is a front section view through an embodiment of the device of  FIG. 1 . 
         FIG. 5  is a side section view through an embodiment of the device of  FIG. 1 . 
         FIG. 6  is a front perspective section view through an embodiment of the device of  FIG. 2  with the top cover removed. 
         FIG. 7  is a rear perspective view of an embodiment of the device of  FIG. 1  showing a transparent support block with the top cover removed. 
         FIG. 8  is a perspective view of the device of  FIG. 1  with the top cover and support block removed. 
         FIG. 9  is a schematic view of certain components of an embodiment of a sensor system usable in the hand held manipulation device. 
         FIG. 10  is a graph showing the change in the coupling force (labeled attraction force) with the change in vertical face distance between the internal and external magnetic field sources. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate various embodiments of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DESCRIPTION 
     Numerous specific details are set forth to provide a thorough understanding of the overall structure, function, manufacture, and use of the embodiments as described in the specification and illustrated in the accompanying drawings. It will be understood by those skilled in the art, however, that the embodiments may be practiced without such specific details. In other instances, well-known operations, components, and elements have not been described in detail so as not to obscure the embodiments described in the specification. Those of ordinary skill in the art will understand that the embodiments described and illustrated herein are non-limiting examples, and thus it can be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the embodiments, the scope of which is defined solely by the appended claims. 
     In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below. 
     Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” or “an embodiment”, or the like, means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” or “in an embodiment”, or the like, in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Thus, the particular features, structures, or characteristics illustrated or described in connection with one embodiment may be combined, in whole or in part, with the features structures, or characteristics of one or more other embodiments without limitation. 
     It will be appreciated that the terms “proximal” and “distal” may be used throughout the specification with reference to a clinician manipulating one end of an instrument used to treat a patient. The term “proximal” refers to the portion of the instrument or component described that is closer to the clinician and the term “distal” refers to the portion located farther from the clinician. It will be further appreciated that for conciseness and clarity, spatial terms such as “vertical,” “horizontal,” “up,” and “down”, “upper” and “lower”, “top” and “bottom”, and the like, may be used herein with respect to the illustrated embodiments. However, surgical instruments may be used in many orientations and positions, and these terms are not intended to be limiting and absolute. 
     As used herein, the term “elevational position” with respect to one or more components means the distance of such component or components above a floor or ground or bottom position of another component or reference point without regard to the spatial orientation of the respective components. 
     As used herein, the term “biocompatible” includes any material that is compatible with the living tissues and system(s) of a patient by not being substantially toxic or injurious and not known to cause immunological rejection. “Biocompatibility” includes the tendency of a material to be biocompatible. 
     As used herein, the term “operatively connected” with respect to two or more components, means that operation of, movement of, or some action of one component brings about, directly or indirectly, an operation, movement or reaction in the other component or components. Components that are operatively connected may be directly connected, may be indirectly connected to each other with one or more additional components interposed between the two, or may not be connected at all, but within a position such that the operation, movement, or action of one component effects an operation, movement, or reaction in the other component in a causal manner. 
     As used herein, the term “operatively suspended” with respect to two or more components, means that one component may be directly suspended from another component or may be indirectly suspended from another component with one or more additional components interposed between the two. 
     As used herein, the term “patient” refers to any human or animal on which a suturing procedure may be performed. As used herein, the term “internal site” of a patient means a lumen, body cavity or other location in a patient&#39;s body including, without limitation, sites accessible through natural orifices or through incisions. 
     The manipulation device  10  is structured to manipulate a magnetic coupling force across living tissue  200  between objects having, or associated with, magnetic fields. The manipulation device  10  may generally include a magnetic field source assembly, a magnetic force monitoring system, and an actuation assembly, including an actuator  18 , for adjusting the magnetic coupling force. The magnetic field source assembly generally includes at least one outer fixed magnet  40  and at least one inner, rotatable magnet  48 . The magnetic force monitoring system generally includes a sensor plate  68  and a sensor  100  in communication with a controller  160 . The actuation assembly may be in the form of a gear assembly that may generally include, in addition to actuator  18 , a rack and pinion gear set comprised of rack  110  and pinion gear  88 , arms  34  and  22  operatively connecting the rack and pinion gear set to actuator  18  and a drive shaft  44 . 
     Adjustments to the magnetic coupling force may be made in various embodiments of the device  10  by adjustments to the actuator  18  by signals from a control unit  160  in response to the monitored magnetic force. As explained in more detail below, the actuator  18  may adjust the movement of the actuation assembly which results in rotation of the rotatable magnet  48  which adjusts the magnetic field strength. 
     The magnetic field source assembly includes an external magnetic field source that provides a magnetic field across tissue  200 . In MAGS applications, there is an object  210 , as shown in  FIG. 1B , positioned in use on an internal site  220  of a patient, across the tissue  200  (e.g., the abdominal wall or other tissue barrier between the inside and the outside of the patient) from the externally positioned manipulation device  10 . The internal object  210  is itself, or is operatively connected to another component that is, a source of an internal magnetic field. The external magnetic field of the magnetic field source assembly and the internal magnetic field source create a magnetic coupling force wherein the internal object  210  is magnetically coupled across the tissue  200  to the magnetic field source of the externally positioned manipulation device  10 . 
     Lateral movement of the manipulation device  10  over the external surface of the tissue  200  causes a similar lateral movement of the internal object  210  on the internal surface of the tissue. If the magnetic coupling force is too strong, however, lateral movement may be difficult due to the resistance to movement by the strongly attracted, magnetically coupled objects, or if too weak the internal object  200  will not remain attached or well controlled by manipulation device  10 . Based on the monitored force generated between the external and internal magnetic field sources, the manipulation device  10  described herein enables control of the magnetic coupling force to maintain the force at a level that is strong enough to hold the internal object  210  while allowing lateral movement of the manipulation device  10  and the good control of internal object  210 . 
     Referring to  FIGS. 1A  and B, an embodiment of a fully assembled manipulation device  10  is shown that includes a housing  12 , a support block  16  mounted above housing  12 , a side mounted actuator  18  with a control arm  22  extending into support block  16 , and a cover  14 . In the embodiment shown, actuator  18  may be any suitable actuator, such as a motor, and in particular, a servo motor, DC motor with gear train, a stepper motor, or the like. Actuator  18  may be powered by any suitable DC power supply, a self contained battery, or by a pneumatic or hydraulic power supply. Alternatively, the actuator may itself be a pneumatic or hydraulic motor. Actuator  18  is held to housing  12  by a bracket  20  that extends outwardly from one side of housing  12 . Bracket  20  may be an integral part of housing  12  or may be a separate section fastened to housing  12 . Actuator  18  may be secured to bracket  20  by any suitable fasteners  28 , such as bolts, screws, or clips or may be welded to bracket  20  or directly to housing  12 . Actuator  18  may be electrically connected to a controller  160 , such as a circuit board via wire  30 . Controller  160  may be a separate, distinct unit remotely positioned from manipulation device  10  or may be housed within or mounted to device  10  in the form of an internal circuit board or one or more microchips. Electrical or other communication signals to actuator  18  may be controlled by an external or internal program or algorithm in response to the sensed magnetic coupling force. The program or algorithm controls the movement of arm  22  of actuator  18 . Arm  22  may be moved in a continuous manner or in increments as directed by input from controller  160 . 
     The manipulation device  10  includes a magnetic field source assembly. In various embodiments, the magnetic field source assembly is housed in housing  12  and includes one or more outer magnets  40  and an inner magnet  48 . (See for example,  FIG. 4 ) The outer magnet or magnets  40  are suspended from a block  60 , for example, by magnetic attraction between the magnets  40  and block  60 . In embodiments of the manipulation device  10  having two outer magnets  40 , block  60  serves as a bridge to lock the outer magnets  40  into position relative to each other. In certain embodiments, the two outer magnets  40  are of equal and opposite magnetism. When block  60  is made of carbon steel, block  60  acts as a bridge magnetically connecting the North pole on one magnet  40  to the South pole on the opposite magnet  40 . Once installed, the magnets  40  and block  60  are magnetically fixed to each other. Those skilled in the art will recognize that other means of attachment between magnets  40  and block  60  may be provided, such as fasteners, in the form of bolts, screws, complementary engagements surfaces and the like. 
     In various embodiments, the outer magnet or magnets  40  define a cavity  42  in which the inner magnet  48  is positioned for movement relative to the outer magnet or magnets  40 . Outer magnet  40  may be a single unit defining an open ended cavity  42 . Alternatively, as shown in  FIGS. 2 and 3 , there may be two outer magnets  40  positioned side by side in a facing spaced relationship relative to each other. In certain embodiments, the facing sides  120  of each of the two outer magnets  40  may be concave or arced in configuration, together defining a generally cylindrical cavity  42  with a gap  122  between each of the two opposing ends  106  of each outer magnet  40 . 
     The inner magnet  48  is suspended within the cavity  42  with sufficient space to allow the inner magnet  48  to rotate. In various embodiments, inner magnet  48  rotates within the cavity  42  of the outer magnet or magnets  40 . In such embodiments, the rotation of the inner magnet  48  affects the magnetic flux for adjusting the magnetic coupling force between the external magnetic field source assembly and the internal magnetic field source associated with object  210 . The configuration of cavity  42  may take any shape that allows inner magnet  48  to freely rotate within the space between the sides of the outer magnet or magnets  40 . As shown in the figures, in various embodiments, inner magnet  48  may be cylindrical in shape and is attached to a drive shaft  44  so that inner magnet  48  rotates with drive shaft  44  about a central axis within cavity  42 . In various embodiments, the direction and degree of rotation of the inner magnet  48  may be changed from clockwise to counterclockwise and vice versa automatically in response to signals from a sensor  100  to the controller  160  which then, based on the desired coupling force, adjusts the force that the external magnetic field source exerts over the internal magnetic field source and its associated internal object  210  by adjusting the actuation of the gear assembly. 
       FIGS. 2 and 3  illustrate an exemplary embodiment of the operative connection between the gear assembly and the magnetic field assembly. In various embodiments, the actuation assembly may be in the form of a gear assembly that generally includes drive shaft  44  and a rack and pinion gear set, comprised of rack  110  and pinion gear  88 . The magnetic field source assembly, as stated above, includes inner magnet  48 , outer magnet or magnets  40 , and cavity  42 . A distal portion of drive shaft  44  extends into cavity  42  and includes a base section  46  to aid in supporting inner magnet  48  above the floor  108  of housing  12 . An annular bushing  56  surrounds base section  46  and sits under inner magnet  48  on the floor  108  of housing  12  within cavity  42 . Shaft  44  may be any configuration provided that it can rotate about the axis of rotation within cavity  42 . In various embodiments, shaft  44  may have an upper proximal portion that is circular in cross-section and a lower, distal portion  58  that is rectangular in cross-section, as shown in  FIGS. 3 and 5 , to securely engage inner magnet  48  to drive shaft  44  so that magnet  48  moves with drive shaft  44 . In other embodiments, drive shaft  44  may be, for example, generally circular in cross-section along its full length. In such embodiments, inner magnet  48  may be secured to drive shaft  44  or base section  46  or both by one or more pins or other fasteners, or may be press fit onto shaft  44  to ensure that inner magnet  48  moves with drive shaft  44 . 
     An annular bearing surface  50  and rotating annular bearing  52  are shown in the embodiment of  FIG. 4  to be positioned within cavity  42  above inner magnet  48  and surrounding drive shaft  44 . Bearings  50 ,  52  above inner magnet  48  and bushing  56  below inner magnet  48  facilitate the ability and ease with which inner magnet  48  rotates within cavity  42 . 
     In certain embodiments, as shown in  FIGS. 4-6 , the additional components of the gear assembly and the magnetic field monitoring system may be housed in and/or supported by support block  16 . Block  60  may serve as a platform for support block  16  and various components of the gear assembly. Alternatively, suspension block  60  may serve as a platform for various components of the gear assembly and support block  16  may be attached to housing  12 . For example, fasteners  78  may be inserted into bores  98 , as shown in  FIG. 7 , in support block  16  and pass into the upper rim of housing  12 . Support block  16  may include side walls  36  and a top surface  38  and define a cavity  72  on its interior. In various embodiments, the cavity  72  may be configured to have differently sized sections  71  and  73  for housing differently sized components of the gear assembly. A well  96  formed in the top surface  38  of support block  16  seats the sensor  100 . 
     The actuation assembly is operatively connected to and is powered by the actuator  18 . In various embodiments, the actuation assembly is a gear assembly that is connected to the actuator  18  through a series of operatively connected interactive gears. Referring to  FIGS. 4-6 , the gear assembly may include drive shaft  44  and a rack and pinion gear set comprised of pinion gear  88  having gear teeth  116 , and rack  110  having gear teeth  114 . In the embodiment shown, drive shaft  44  extends from the floor  108  of housing  12  proximally through cavity  42  and through a bushing  62  within an opening, for example, in the form of a bore in suspension block  60 , through pinion gear  88  in cavity section  71  of support block  16 , and through an opening  76  in the top of a holder, such as L-shaped bracket  74 , positioned in cavity section  73  of support block  16 . Pinion gear  88  is mounted over drive shaft  44 . Pinion gear  88  may be secured to drive shaft  44  by any suitable fastening member, such as set screw  102  which is shown in  FIG. 6  extending into a recess  86  along a side near the proximal end of drive shaft  44 . A bearing surface, for example, roller ball bearings  80 , sits above pinion gear  88  within the opening  76  in L-shaped bracket  74  surrounding drive shaft  44 . Additional bearing surfaces  90  and  92  sit under pinion gear  88 , also surrounding drive shaft  44 . A set screw  82  extending into a central longitudinal bore  84  in the proximal end of drive shaft  44  locks drive shaft  44  and roller bearings  80  to the top of L-shaped bracket  74 , pulling this portion of the gear assembly together. A hole  146  in block  16  through the well  96  provides access for a tool to adjust set screw  82  if necessary during assembly. 
     As shown in the embodiment of  FIGS. 2 ,  7 , and  8 , the gear assembly may include a rack  110  pivotally connected at one end at pivot point  118  to arm  34 . Arm  34  is pivotally connected at pivot point  26  to arm  22  and arm  22  is pivotally connected at pivot point  32  to actuator  18 . Rack  110  passes through openings  130  in the upwardly extending sections  132  of support bracket  136  in cavity section  71  of support block  16 . Support bracket  136  is attached to suspension block  60  by fasteners  66  which extend through bushing portions  94  of bracket  136  into bore  64 . Fasteners  66  may be any suitable fastener, such as screws, bolts, clips and the like. Washers  138  or any suitable bearing surface may be positioned at each opening  130  around rack  110 . Actuator  18  may power the reciprocal movement of arm  22  back and forth, towards or away from housing  12 , effecting the corresponding movement of arm  34  and the corresponding linear movement of rack  110 . Gear teeth  114  on rack  110  engage gear teeth  116  on pinion gear  88 . The linear movement of rack  110  is translated into, or effects, rotational movement of pinion gear  88  through engagement of the gear teeth  114  and  116 . As described previously, pinion gear  88  is mounted on and/or operatively connected to drive shaft  44 , such that the clockwise or counterclockwise rotation of pinion gear  88  causes the clockwise or counterclockwise rotation, respectively, of drive shaft  44 . As drive shaft  44  rotates, inner magnet  48  rotates with drive shaft  44  within cavity  42 . If arm  22  is moving incrementally and/or moving in a reciprocal motion, inner magnet  48  will move incrementally and/or change its direction of rotation as arm  22  changes direction. 
     The manipulation device  10  exercises automatic control over the magnetic coupling force. A magnetic coupling force monitor is provided in various embodiments of the manipulation device  10 . The magnetic coupling force monitoring system may include a sensor  100  and sensor plate  68 . Sensor  100  is supported by support block  16 . In certain embodiments, sensor  100  may be seated in a well  96  of support block  16 . A post  140  extends proximally from sensor  100 . Sensor plate  68  rests on post  140  of sensor  100 , above the top surface  38  of support block  16 , in contact with sensor  100 . A hole  142  through sensor plate  68  is provided for insertion of a tool to adjust sensor  100  during assembly or in use thereafter if necessary. 
     A plurality of bolts  70 , such as the four bolts  70  shown in the figures, pass through openings in sensor plate  68 . In the embodiments shown in the figures, bolts  70  have a smooth upper or proximal shoulder and surface and a lower threaded end that engages the suspension block  60 . The smooth surface portion passes through openings in plate  68  and through bushings  104 . Bushings  104  sit in counter bores in block  16 . The smooth portion of each bolt  70  is smaller in diameter than the diameter of the bushing  104  into which the bolt  70  is inserted to provide sufficient clearance so that bolts  70  can slide easily relative to bushings  104 . Bolts  70  may also be smaller in diameter than the diameter of the openings in sensor plate  68  through which bolts  70  pass to provide sufficient clearance so that bolts  70  can slide easily relative to sensor plate  68 . 
     Referring to  FIGS. 4-5 , in various embodiments, there may be a gap  144  between a portion of the bottom  148  of sensor plate  68  and a portion of the top 38 of support block  16 . As described above, sensor plate  68  slides freely relative to bolts  70 . Thus, sensor plate  68  is operatively suspended above or “floating” between cover  14  and sensor  100 , above but in contact with sensor  100  through post  140 . As the magnetic coupling force between the internal magnetic field source and the external magnetic field source assembly increases, the external magnets  40  and  48  are pulled in distally, towards the internal magnetic field source. In various embodiments, magnets  40  are fixedly attached to suspension block  60  by magnetic attraction or other means. The downwardly, or distally directed pull on magnets  40  pulls on blocks  60  and bolts  70 , which are connected at their distal ends to block  60 . The smooth surface on the upper or proximal portions of bolts  70  allow bolts  70  to slide easily through bushings  104  in support block  16  and the openings in sensor plate  68  with little or no significant resistance, and in certain embodiments, no resistance. As the distally directed force increases, the heads of bolts  70  apply the distally directed force to sensor plate  68  which applies an increased distally directed force to post  140  of sensor  100 . As magnets  40  and suspension block  60  are pulled in the distal direction as a result of increased magnetic coupling forces across the tissue  200 , sensor plate  68  applies a greater force against sensor  100 . Sensor  100  is zeroed out at a value that accounts for the weight of sensor plate  68  and gravity. As the magnetic coupling force between the internal magnetic field source and the external magnetic field source assembly decreases, the magnetic pull from the internal magnetic field source relaxes. The relaxation in force is transferred through magnets  40 , blocks  60  and  16  to bolts  70  and sensor plate  68 , allowing sensor plate  68  to relax relative to sensor  100 . Sensor  100  detects the change in the force applied by sensor plate  68  and communicates the change to controller  160 . A wire may extend from sensor  100  to controller  160  to communicate the sensed signal from sensor  100  to controller  160 .  FIG. 9  illustrates schematically the communication from sensor  100  to controller  160 . 
     As the elevational position of magnets  40  relative to the internal magnetic field source is changed up or down as the magnetic coupling force changes, the force applied to sensor  100  by sensor plate  68  changes accordingly. Because the weight of the sensor plate  68  in a rest position where there is no magnetic coupling force applying a distally directed force on sensor plate  68  is accounted for in calibrating the controller  160 , the only force measured when there is a force applied to sensor  100  is the magnetic coupling force between the external magnetic field source and the internal counterpart. 
     The controller  160  receives a signal from the sensor  100  as to the magnitude of force generated by the magnetic attraction between the external magnetic field source assembly and the internal magnetic field source associated with object  210 . As the thickness of tissue  200  gets smaller, the field strength becomes stronger thereby increasing the force on sensor  100 . Conversely, as the thickness of tissue  200  gets larger the magnetic field strength becomes weaker reducing the force on sensor  100 . For example, at a distance of 5 mm between the vertical faces of the external and internal magnetic field sources, at about 180 degrees of rotation, the load may be 28 lbs, and at zero degrees of rotation, the load may be at 7 lbs. A graph is provided in  FIG. 10  showing the change in the coupling force (labeled attraction force) with the change in vertical face distance between the internal and external magnetic field sources. Data is shown for rotatable magnet  48  when at 0 and 180 degrees of rotation. It should be understood, however, that 0 and 180 degrees are arbitrary. Zero is representative of low/off, and 180 is representative of more power. The force output of this embodiment can be anywhere between these two extremes, i.e., 180 is the maximum and zero is the minimum. The result is symmetric, anything less than 180 degrees is equal to that angle over 180 degrees, e.g., the force at 90 and 270 degrees are equal, both in scale and sign. Only the angle matters. The direction of the angle does not matter in changing the magnetic flux generated by the rotatable magnet  48 . 
     The sensor  100  may be, for example, a transducer, a piezoelectric film sensor, or a load cell. The magnetic coupling force pulls the magnets  40 ,  48 . The sensor  100  senses the force and communicates the sensed force to a control unit  160 . The control unit  160  may be or may include a circuit board. The circuit board may, for example, utilize a programmable controller (e.g., EPROM) to analyze signals from the sensor  100 . Magnetic field lines are established by the magnetic field between the external and internal magnets, pulling the magnets in the magnet housing  12  down, toward the internal magnets associated with the object  210  within the patient. As the downward pull increases, it increases the force applied by the sensor plate  68  to the sensor  100 , causing the sensor  100  to measure and register an increased force against it. The sensor  100  signals the calculated force back to the control unit  160  wirelessly or via circuitry. As stated above, the sensor  100  is adjusted to have a zero point accounting for gravity plus the weight of the sensor plate  68 . 
     Those skilled in the art will appreciate that other types of sensors may be used. A LCD screen may be provided to show the force generation between the internal and external magnets. 
     If sensor  100  is a load cell type of sensor, for example, it feeds the load signal to a signal conditioner. The load cell  100  is acted upon by the attractive forces between the internal and the external magnets. The load cell  100  strains internally and the resulting strain is measured in terms of electrical resistance, using current provided by any suitable power supply. The signal conditioner, which may be contained within the control unit  160 , amplifies the signal from the load cell  100  and then a suitable algorithm may be used to calculate the actual force which is then used to drive the actuator  18  at a calculated speed and duration to adjust gear assembly and thereby adjust the rotation of inner magnet  48 . Changes to the direction and degree of rotation of magnet  48  adjust the magnetic flux created by the inner magnet  48 . 
     Control unit  160  is equipped with a receiver to receive the signals from sensor  100 . Software analyzes the received signals, and sends output signals to instruct the actuator  18 . An exemplary commercially available software program suitable for use with the manipulation device  10  is LabVIEW™ system design software sold by National Instruments Corporation. Actuator  18  may be a servo motor or a stepper type motor which, as explained above, will reciprocate arm  22  to move rack  110  and pinion gear  88  and thereby drive the drive shaft  44 , which effects rotation of inner magnet  48  in a direction that will match a predetermined force such as the magnetic field strength between the external and internal magnetic field sources. When the predetermined force is sensed by sensor  100 , the sensed signals are communicated to the control unit  160  which, as before, instructs the actuator  18  to stop. The continuous monitoring in use of the magnetic coupling force provides an automatic closed loop feedback system to control the magnetic coupling force. The control unit  160  may be on any suitable printed circuit board that receives analog or digital signals and may be packaged within or external to the housing  12  of the manipulation device  10 .  FIG. 9  shows a schematic of the signal communication from sensor  100  to the control unit  160  to actuator  18 . 
     The predetermined force will be the minimum force that is necessary to attract and accurately control the internal object  210  associated with the internal magnet. The internal magnet must be held with enough magnetic force to prevent it from falling away from the internal body wall. The maximum amount of force would be less than a force that compresses or squeezes the tissue  200  or prevents control over the internal object  210 . Those skilled in the art will appreciate that a range of acceptable force may apply and may vary with the patient. The surgeon has to be able to move the manipulation device  10  relatively easily across the patient&#39;s body to control the internal magnet associated with internal object  210  without so much drag that movement is difficult. 
     The embodiments of the devices described herein may be introduced inside a patient using minimally invasive or open surgical techniques. In some instances it may be advantageous to introduce the devices inside the patient using a combination of minimally invasive and open surgical techniques. Minimally invasive techniques may provide more accurate and effective access to the treatment region for diagnostic and treatment procedures. To reach internal treatment regions within the patient, the devices described herein may be inserted through natural openings of the body such as the mouth, nose, anus, and/or vagina, for example. Minimally invasive procedures performed by the introduction of various medical devices into the patient through a natural opening of the patient are known in the art as NOTES™ procedures. Some portions of the devices may be introduced to the tissue treatment region percutaneously or through small—keyhole—incisions. 
     Endoscopic minimally invasive surgical and diagnostic medical procedures are used to evaluate and treat internal organs by inserting a small tube into the body. The endoscope may have a rigid or a flexible tube. A flexible endoscope may be introduced either through a natural body opening (e.g., mouth, nose, anus, and/or vagina) or via a trocar through a relatively small—keyhole—incision incisions (usually 0.5-2.5 cm). The endoscope can be used to observe surface conditions of internal organs, including abnormal or diseased tissue such as lesions and other surface conditions and capture images for visual inspection and photography. The endoscope may be adapted and configured with working channels for introducing medical instruments to the treatment region for taking biopsies, retrieving foreign objects, and/or performing surgical procedures. 
     All materials used that are in contact with a patient are preferably made of biocompatible materials. 
     Preferably, the various embodiments of the devices described herein will be processed before surgery. First, a new or used instrument is obtained and if necessary cleaned. The instrument can then be sterilized. In one sterilization technique, the instrument is placed in a closed and sealed container, such as a plastic or TYVEK®bag. The container and instrument are then placed in a field of radiation that can penetrate the container, such as gamma radiation, x-rays, or high-energy electrons. The radiation kills bacteria on the instrument and in the container. The sterilized instrument can then be stored in the sterile container. The sealed container keeps the instrument sterile until it is opened in the medical facility. Other sterilization techniques can be done by any number of ways known to those skilled in the art including beta or gamma radiation, ethylene oxide, and/or steam. 
     Although the various embodiments of the devices have been described herein in connection with certain disclosed embodiments, many modifications and variations to those embodiments may be implemented. For example, different types of end effectors may be employed. Also, where materials are disclosed for certain components, other materials may be used. The foregoing description and following claims are intended to cover all such modification and variations. 
     Any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated materials does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.