Patent Publication Number: US-2020289140-A1

Title: Laparoscopic graspers and systems therefor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application Ser. No. 61/929,918, filed on Jan. 21, 2014, and titled “Laparoscopic Graspers and Systems Therefor,” the contents of which are hereby incorporated in their entirety. 
    
    
     FIELD 
     The present invention is directed toward systems, devices, and methods for providing remote manipulation or traction to tissue using one or more graspers, delivery devices, and magnetic control assemblies. 
     BACKGROUND OF THE INVENTION 
     Many surgical procedures are shifting toward the use of minimally-invasive approaches that are configured to minimize the number and size of incisions that are made in a patient. Minimally-invasive procedures such as endoscopic and laparoscopic procedures may be associated with lower pain, quicker post-surgical recovery, shortened hospitalization, and reduced complications when compared to open surgical procedures. During minimally-invasive procedures it may be desirable to reposition or otherwise manipulate tissue. However, the introduction of additional devices to engage tissue may crowd the access sites provided by incisions, which may require the formation of larger or additional access sites. Accordingly, it may be desirable to provide one or more systems that allow for manipulation of tissue without the need to have a portion of the device present in an access site to the body. 
     BRIEF SUMMARY OF THE INVENTION 
     Described here are systems, devices, and methods for providing remote manipulation or traction to tissue. In some variations, the systems may comprise some combination of a grasper configured to be inserted into a patient, a delivery device, and a magnetic control element. The grasper may be configured for insertion into the patient during a minimally-invasive procedure, such as a laparoscopic operation. The graspers described here may be configured to releasably connect to tissue. In some embodiments, the grasper may comprise a clip, a clamp, a suction device, a coil, or the like, and may be configured to connect to any suitable tissue of the body (for example, including but not limited to tissue in the abdominal cavity, such as an appendix, a gallbladder, or the like). Accordingly, the grasper may be sized such that it may fit through a laparoscopic port (e.g., a 10 mm port or the like) or another incision formed in the body. In some instances, the grasper may be introduced into the body via an incision or port using a delivery device. The delivery device may be configured to releasably engage the grasper to deliver the grasper, remove it from the patient, or reposition it. The delivery device may additionally be configured to actuate the grasper to attach it to tissue and/or detach it from tissue. The grasper may be further configured to be manipulated by a magnetic control element positioned externally of the body to move, reposition, and/or hold the grasper. 
     The grasper may be any suitable device for releasably connecting to tissue, such as those described here. In some variations, the grasper may be a clip, clamp, or the like, which may attach to tissue by pressing or otherwise holding tissue between two surfaces. In other variations, the grasper may be a suction device, which may attach to tissue by creating a vacuum between the grasper and tissue. In yet other variations, the grasper may comprise a wire having a pre-formed shape such as a coil, which may attach to tissue by ensnaring it. The delivery devices may be any suitable device configured to deliver the grasper to the area of the tissue of interest, and the delivery device may be further configured to actuate the grasper to selectively connect the grasper to tissue or to detach the grasper from tissue. 
     The magnetic control element may be configured to be positioned outside the body and to provide a magnetic force to the grasper when the grasper is positioned inside the body. The magnetic field produced by the magnetic control assembly may provide one or more forces to the grasper to control the position of the grasper and the attached tissue. The magnetic control element may have any suitable configuration, and in some variations may comprise at least one magnet configured to generate a magnetic field and at least one force modulation device. The force modulation device may control the magnitude of the force applied to the magnetic device. 
     In some variations, the systems described herein comprise a system for manipulating tissue, comprising a grasper configured to be attached to tissue in a body of a patient, a delivery device configured to releasably engage the grasper and to actuate the grasper between a first configuration and a second configuration, and a magnetic control assembly comprising a magnet configured to generate a magnetic field and to apply a magnetic force to the grasper. In some variations, the grasper comprises a magnetic or ferromagnetic material. In some of these variations, the grasper further comprises two members connected by a pivot joint, wherein the two members are configured to attach to tissue by holding the tissue between the two surfaces. In some of these variations the delivery device comprises a cylindrical shaft having a lumen therethrough and a collet having a lumen therethrough and configured to be located at least partially within the lumen of the cylindrical shaft, wherein the grasper is configured to be located at least partially within the lumen of the collet and to be actuated by motion of the cylindrical shaft relative to the collet. In some of these variations, the grasper and delivery device each comprise a central longitudinal axis, and wherein the grasper is configured to be engaged by the delivery device when the central longitudinal axis of the delivery device is offset from the central longitudinal axis of the grasper by up to 90 degrees. In some variations, the grasper is configured to attach to tissue using suction. In some variations, the grasper comprises a wire having a coiled shape in the second configuration, and wherein the coiled shape is configured to ensnare tissue. In some variations, the grasper comprises two arms having an open configuration and a closed configuration, wherein the arms are configured to attach to tissue by holding the tissue between two surfaces in the closed configuration, and wherein the two arms are connected via a linkage assembly having an expanded configuration and a collapsed configuration and comprising a plurality of struts and a plurality of pivot joints. In some of these variations, the two arms can be moved from the open configuration to the closed configuration by moving the linkage assembly from the expanded configuration to the collapsed configuration. In some of these variations, the two arms can be moved from the open configuration to the closed configuration by moving the linkage assembly from the collapsed configuration to the expanded configuration. 
     In some variations, the methods described herein comprise a method of performing minimally invasive surgery, comprising positioning a grasper within a body of a patient using a delivery device, attaching the grasper to tissue within the body of the patient using the delivery device to actuate the grasper, disengaging the delivery device from the grasper, positioning a magnetic control assembly externally of the body, wherein the magnetic control assembly comprises a magnet configured to generate a magnetic field and apply a magnetic force to the grasper, and applying the magnetic force to the grasper to manipulate the magnetic device. In some variations, the methods further comprise reengaging the grasper with the delivery device. In some of these variations, the method further comprises using the delivery device to actuate the grasper to detach the grasper from the tissue. In some of these variations, the method further comprises repositioning the grasper to a new area of tissue. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1C  depict perspective views of a variation of the systems described here having a grasper and a delivery device. 
         FIG. 2  depicts a perspective view of a variation of the delivery devices described here. 
         FIGS. 3A-3C  depict perspective views of a variation of the systems described here. 
         FIGS. 3D-3F  depict cross-sectional side views of additional variations on the systems described here. 
         FIGS. 4A-4B  depict perspective and side views, respectively, of a variation of the systems described here  FIG. 4C  depicts a side view of the graspers of the system of  FIGS. 4A-4B . 
         FIG. 5A  depicts a side view of a variation of systems described here.  FIGS. 5B-5C  depict side views of the graspers of the system of  FIG. 5A .  FIGS. 5D-5E  depict side views of an additional variation of graspers described here. 
         FIGS. 6A-6B  depict side and perspective views, respectively, of a variation of the systems described here. 
         FIGS. 7A-7B  depict side views of a variation of the systems described here. 
         FIGS. 8A-8B  depict perspective views of a variation of the systems described here. 
         FIGS. 9A-9B  depict perspective views of a variation of the systems described here. 
         FIG. 10  depicts a block diagram of a variation of the systems described here. 
         FIGS. 11A-11B  depict perspective views of a variation of the systems described here. 
         FIGS. 12A-12B  depict perspective views of a variation of the systems described here. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Described here are devices, systems, and methods for providing remote manipulation of tissue during minimally-invasive procedures. Generally, the systems described here include a grasper that is configured to be releasably connected to tissue. The grasper may be further configured to be attracted to one or more magnets positioned externally of the body. The systems described here may also comprise a delivery device. The delivery devices described here are generally configured to releasably carry the grasper, and may be further configured to actuate the grasper to selectively connect the grasper to tissue or detach the grasper from tissue. The delivery devices are typically further configured to release the grasper from the delivery device (e.g., after the grasper has been connected to tissue). In some variations, the system may further comprise a magnetic control element comprising one or more magnets, which may be configured to be positioned outside the body and to provide a magnetic force to the grasper when the grasper is positioned in the body. While illustrative examples of the graspers and delivery devices are described together herein, it should be appreciated that any of the graspers may be actuated and delivered using any suitable delivery device, and that that the delivery devices described here may be used to actuate and deliver any suitable grasper. 
     Generally, the methods described here comprise releasably connecting a grasper (such as one of the graspers described here) to a tissue, and providing a magnetic force to the grasper to move and/or hold the grasper and to provide traction of the tissue engaged by the grasper. The magnetic force may be provided by a magnetic control element configured to magnetically attract the grasper from a position outside the body. In some variations, the grasper may be releasably connected to a tissue inside of the body, and the magnetic control element may be positioned externally of the body to magnetically attract the grasper. To connect the grasper to the tissue, the grasper may be releasably coupled with a delivery device, wherein the delivery device is configured to actuate the grasper. The delivery device may actuate the grasper to releasably connect the grasper to tissue, and may decouple from the grasper after the grasper is connected to tissue. In some instances, the delivery device may be used to repositioned the grasper and reattached it to tissue (either the same tissue or a different tissue), or to remove the grasper and/or tissue from the body. 
     Devices and Systems 
     As mentioned above, the systems described here may comprise a grasper configured to be releasably connected to tissue. In some variations, the grasper may comprise a clip, clamp, or the like, which is configured to attach to tissue by pressing or otherwise holding tissue between two surfaces.  FIGS. 1A-1C  depict perspective views of one variation of a system  101  as described here. As shown there, the system  101  may comprise a grasper comprising a clip  100  and a delivery device  150 . The clip  100  may be releasably coupled to the delivery device  150  (as shown in  FIGS. 1A-1C ), and may be decoupled from the delivery device. When the clip  100  is coupled to the delivery device  150 , the delivery device  150  may actuate the clip  100  between an open configuration (as shown in  FIGS. 1B and 1C ) and a closed configuration (as shown in  FIG. 1A ) to connect the clip  100  to tissue or detach the clip  100  therefrom, as described in more detail herein. 
     In some variations, the delivery device  150  and the clip  100  may be configured for laparoscopic introduction into the body. In these variations, the clip  100  may be sized such that it may be advanced through a laparoscopic port. In some instances, the clip  100  may be sized such that it may fit through a laparoscopic port when the clip  100  is in the open configuration, in the closed configuration, or either the open or closed configuration. In some of these variations, the largest width of the clip  100  in a closed configuration may be less than or equal to about 10 mm, so that the clip  100  may be advanced through a 10 mm laparoscopic port when the clip is in the closed configuration. Similarly, a distal portion of the delivery device  150  may also be sized such that it may fit through a laparoscopic port. In some variations, the delivery device  150  may be configured such that the distal portion of the delivery device  150  (e.g., a cylindrical wall  156 , as discussed in more detail herein) may have a diameter less than or equal to about 10 mm. The clip  100  and delivery device  150  may be formed from any suitable materials, such as one or more of medical grade, high-strength plastics or metals, such as stainless steel, cobalt chromium, nickel titanium, PEEK, one or more nylons, polyimide, or the like, and/or may at least partially be formed from magnetic materials, as described herein. Additionally, in some instances a portion of the delivery device (such as a shaft of the delivery device) may have a diameter of about 5 mm or less, such that additional devices may be introduced through a 10 mm port while the delivery device is positioned in the port. 
     The clip  100  illustrated in  FIGS. 1A-1C  may be configured to releasably pinch or grip tissue. As shown in  FIG. 1C , the clip  100  may comprise a first lever arm  102  having a distal portion  108  and a second lever arm  104  having a distal portion  110  rotatably attached to each other by a pivot joint  106 . The first lever arm  102  and the second lever arm  104  may be rotated relative to each other to actuate the clip  100  between closed and open configurations to releasably connect the clip  100  to tissue or release the clip  100  from tissue, respectively. In the open configuration, the distal portions  108  and  110  of the first lever arm  102  and the second lever arm  104 , respectively, may be rotationally positioned away from each other to define a space between the distal portions  108  and  110  of the first lever arm  102  and second lever arm  104 , such as shown in  FIGS. 1B-1C . Similarly, when the clip  100  is in a closed configuration, the distal portions  108  and  110  of the first lever arm  102  and the second lever arm  104  may be rotationally biased toward each other to reduce or eliminate the space between the distal portions  108  and  110  of the first lever arm  102  and the second lever arm  104 . While the distal portions  108  and  110  of the first lever arm  102  and the second lever arm  104  are shown in  FIG. 1A  as contacting each other, it should be appreciated that when clip  100  is connected to tissue, tissue positioned between the first and second lever arms  102  and  104  may prevent the distal portion  108  of the first lever arm  102  from contacting the distal portion  110  of the second lever arm  104  when the clip  100  is placed in the closed configuration. In some variations, the distal portions  108  and  110  of the first lever arm  102  and the second lever arm  104  may be rotationally biased toward each other. For example, in some variations the clip  100  may comprise a spring, such as a torsional spring, which may spring-bias the distal portions  108  and  110  of the first and second lever arms  102  and  104 , respectively, toward each other, which in turn may bias the clip  100  into a closed position. The bias toward the closed configuration may act to hold tissue positioned between the distal portions  108  and  110  of the first lever arm  102  and the second lever arm  104 . 
     The distal portions  108  and  110  of the first and second lever arms  102  and  104 , respectively, may comprise one or more features that may promote engagement with tissue, but need not. In some variations, one or both of inner surfaces  112  and  114  of the distal portions  108  and  110 , respectively, may be roughened or texturized, which may help to reduce slipping between the lever arms and tissue. Additionally or alternatively, the inner surfaces  112  and/or  114  may comprise teeth or ridges  124  (such as shown in  FIGS. 1B-1C ) or other projections that may facilitate engagement of the first and second lever arms  102  and  104  with tissue. In some variations of the clip described here, the clip may comprise one or more coatings that may help to smooth discontinuities in the contours of the clip and may act to provide one or more atraumatic surfaces of the clip. The one or more coatings may comprise silicone, urethane, one or more nylon blends, polyethylenes, fluoropolymers, combinations thereof, and the like. 
     The proximal ends  116  and  118  of the first and second lever arms  102  and  104 , respectively, may be sized and configured to be engaged by a delivery device to releasably couple the clip  100  to a delivery device (such as delivery device  150 , as described in more detail herein). In general, it may be desirable for the graspers described herein to comprise external features on exposed surfaces that may promote the ability of an external instrument (e.g., a delivery device) to remain engaged with the graspers while applying a compressive force to the graspers. For example, the graspers may comprise one or more flat surfaces, recesses, guides (e.g., ridges or channels), or gently curved convex surfaces, such that the instrument is less likely to slip or change positions during grasper actuation. In the variation shown in  FIGS. 1A-1C , these features may comprise protrusions at the proximal ends  116  and  118  of the first and second lever arms  102  and  104 , respectively. For example, in the variation shown in  FIGS. 1A-1C , the proximal ends  116  and  118  of the first and second lever arms  102  and  104 , respectively, may each comprise an outwardly facing hemispherical protrusion (labeled  120  and  122  in  FIGS. 1A-1C ). The hemispherical protrusions  120  and  122  may be configured to engage with features on a delivery device, as described in detail herein. While the protrusions  120  and  122  shown in  FIGS. 1A-1C  are depicted as hemispherical, in other variations one or both of the protrusions  120  and  122  may have another shape. In some variations, one or both of the protrusions  120  and  122  may be spherical. These features may improve the ability of a delivery device to reliably grip onto the clip  100  and to exert a force on the lever arms, as described in detail herein, but need not. In some variations, these features may additionally or alternatively enable the angle between the clip  100  and the delivery device to be adjusted while the clip  100  is engaged by a delivery device, as described in detail herein. 
     Generally, at least a portion of the clip  100  described here may be formed from one or more materials which may be attracted to a magnetic field, as described in more detail herein, but need not be. The materials may include one or more magnetic or ferromagnetic materials, such as, for example, stainless steel, iron, cobalt, nickel, neodymium iron boron, samarium cobalt, alnico, ceramic ferrite, alloys thereof and/or combinations thereof. In variations in which the materials include steel alloys, the steel alloys may be in a martensitic state. In some variations, coldworking may be used to improve the magnetic permeability of the clip  100 , for instance during the machining process. Having at least a portion of the clip  100  formed from one or more metallic or magnetic materials that may be attracted to a magnetic field may allow the clip  100  to be manipulated by a magnetic control assembly, as will be discussed in more detail herein. In some variations, the proximal ends and/or protrusions of the clip  100  may comprise magnetic or ferromagnetic materials to facilitate engagement by the delivery device (as described in more detail herein), but need not. 
     Turning to the variation of the delivery device  150  shown in  FIGS. 1A-1C , the delivery device  150  may comprise a barrel portion  152  and an engagement portion  154 . The barrel portion  152  may comprise a cylindrical wall  156  with a lumen  158  extending therethrough, which may be sized to at least partially hold the engagement portion  154 . The barrel portion  152  and the engagement portion  154  may cooperate to hold and actuate a clip (such as the clip  100  shown in  FIGS. 1A-1C ), as will be discussed in more detail herein. 
     The engagement portion  154  may comprise a first elongate member  160  and second elongate member  162 . The engagement portion  154  may have an open and a closed configuration. In some variations, the first elongate member  160  and second elongate member  162  may be rotatably connected or otherwise attached at their proximal ends  164  and  166 , respectively, but need not be attached. In variations in which the elongate members are attached, the attachment mechanism may allow for the engagement portion  154  to be moved between the open and closed configurations. In some variations, the attachment mechanism may be a pivot joint. In other variations, the first elongate member  160  and second elongate member  162  may be joined, welded or otherwise fused together, and the members may be sufficiently flexible to allow the engagement portion  154  to flex between closed and open configurations. 
     When the engagement portion  154  is moved to the open configuration, the distal portions  168  and  170  of first elongate member  160  and second elongate member  162 , respectively, may be spaced apart to define a space between the distal portions  168  and  170  of first elongate member  160  and second elongate member  162 , as shown in  FIG. 1A . In variations in which the elongate members are attached such that an attachment mechanism rotatably connects the first and second elongate members  160  and  162 , in the open configuration, the distal portions  168  and  170  of the first and second elongate members  160  and  162  may be rotationally positioned away from each other to define a space between the distal portions  168  and  170  of first and second elongate members  160  and  162 . In the closed configuration, the distal portions  168  and  170  of first elongate member  160  and second elongate member  162  may be moved closer than in the open configuration, as shown in  FIGS. 1B-1C . In variations in which the elongate members are attached such that an attachment mechanism rotatably connects the first and second elongate members  160  and  162 , in the closed configuration, the distal portions  168  and  170  of the first and second elongate members  160  and  162  may be rotationally positioned toward each other to reduce or eliminate space between the distal portions  168  and  170  of the first and second elongate members  160  and  162 . 
     While it may be possible for the distal portion  168  of the first elongate member  160  to be moved into contact with the distal portion  170  of the second elongate member  162 , this may not be necessary for the engagement portion  154  to releasably engage a clip. For example, when the engagement portion  154  releasably engages with the clip  100  depicted in  FIGS. 1A-1C , the clip  100  may prevent the distal portions  168  and  170  of the first elongate member  160  and second elongate member  162  from contacting each other, and/or may prevent the first elongate member  160  and second elongate member  162  from fully closing. 
     In some variations, the first elongate member  160  and the second elongate member  162  may be configured such that their distal ends  168  and  170  are biased away from each other, which may in turn bias the engagement portion  154  toward an open configuration. For example, in some variations the engagement portion  154  may comprise a spring (not shown), such as a compression spring, which may spring-bias the engagement portion  154  toward an open position, such as shown in  FIG. 1A . In variations where the first elongate member  160  and second elongate member  162  are welded together, they may be formed in an open configuration but may be sufficiently flexible to allow the first elongate member  160  and second elongate member  162  to be pressed toward each other into a closed configuration. In other variations, the first and second elongate members  160  and  162  may be spring-biased toward each other, for instance with an extension spring, leaf spring, or torsional spring, which may bias the engagement portion  154  toward a closed configuration. In some variations, the delivery device  150  may comprise a control that may be used to overcome the bias of an engagement portion (such as the engagement portion  154 ) toward a closed configuration, which may thus allow the engagement portion  154  to be moved into an open configuration. 
     As mentioned above, the engagement portion  154  of the delivery device  150  may be configured to releasably couple to and actuate a clip, such as the clip  100  shown in  FIGS. 1A-1C . For example, in some instances the distal portions  168  and  170  of first elongate member  160  and second elongate member  162  may be configured to releasably engage the clip  100 . The proximal ends  116  and  118  of the first and second lever arms  102  and  104 , respectively, of clip  100  may be positioned between the distal ends  168  and  170  of the first and second elongate members  160  and  162 , respectively, of the delivery device  150 . The clip  100  may be held between the distal ends  168  and  170  of the first and second elongate members by a clamping force between the distal ends  168  and  170 . For example, in variations in which the engagement portion  154  of the delivery device  150  is biased toward a closed configuration, the biasing force may create a clamping force. 
     In some variations, the distal portions  168  and  170  of the first and second elongate members  160  and  162 , respectively, may comprise features that may improve the ability of the delivery device  150  to reliably grip onto a clip (such as clip  100 ) and to exert a force on the lever arms of a clip, but need not comprise such features. For example, the delivery device  150  may comprise apertures or recesses (e.g., apertures  172  shown in  FIGS. 1A-1C ) extending at least partially through the distal ends  168  and  170  of the first and second elongate members  160  and  162 . When a clip is positioned between the distal ends  168  and  170  of first and second elongate members  160  and  162 , at least a portion of the clip may be configured to sit within one or more of the apertures  172 . For example, each of the hemispherical protrusions  120  and  122  of the clip  100  described with respect  FIGS. 1A-1C  may fit at least partially within a respective aperture  172 . This may help to maintain engagement between the engagement portion  154  and the clip  100  by allowing a greater area of contact between the clip  100  and delivery device  150 , and by the inner walls of the apertures  172  exerting inward forces on the hemispherical protrusions  120  and  122  that may tend to keep the hemispherical protrusions  120  and  122  within the apertures  172 . In some variations, the hemispherical protrusions  120  and  122  may additionally be secured in the apertures  172  by a force biasing the first and second elongate members  160  and  162  toward each other, as described herein. 
     Additionally or alternatively, features of the proximal ends  116  and  118  of the first and second lever arms  102  and  104 , respectively, of the clip  100 , and/or features of the distal portions  168  and  170  of the first and second elongate members  160  and  162 , respectively, of the delivery device  150  may enable a clip (such as clip  100 ) to be engaged by a delivery device (such as delivery device  150 ) from a broad range of angles (e.g. angles of approach wherein the central longitudinal axis of the grasper is offset from the central axis of the delivery device by up to 10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, 90°, or more), assist in delivery and/or retrieval of the grasper, and/or assist in locating the clip  100  for retrieval. For example, the outwardly facing hemispherical protrusions  120  and  122  on proximal ends  116  and  118  of the first and second lever arms  102  and  104  of clip  100  enable the clip to be accessed from a broad range of angles because the rounded surface creates a partially rotationally symmetric contact area for a delivery device. The outwardly facing hemispherical protrusions  120  and  122  may also enable the clip  100  to be more easily located because of the larger size of the hemispherical protrusions  120  and  122  as compared to the proximal ends  116  and  118  of the first and second lever arms  102  and  104 . 
     In some variations, there may be an attractive force between distal portions  168  and  170  of first and second elongate members  160  and  162  and one or more portions of the clip  100  (e.g., the distal portions  116  and  118  and/or protrusions  120  and  122 ). In some variations, this attractive force may be magnetic. In variations in which the attractive force is magnetic, the magnetic force may be generated by the distal portions  168  and  170  of the first and second elongate members  160  and  162 , and one or more portions of the clip  100 , wherein each of these components comprises one or more magnetic or ferromagnetic materials. For example, in variations in which one or more portions of a clip (e.g., the distal portions  116  and  118  and/or protrusions  120  and  122  of the clip  100 ) comprise magnetic materials, the distal portions  168  and  170  of the elongate members  160  and  162  may comprise magnetic or ferromagnetic materials; in variations in which one or more portions of a clip (e.g., the distal portions  116  and  118  and/or protrusions  120  and  122  of the clip  100 ) comprise ferromagnetic materials and no magnetic materials, the distal portions  168  and  170  of the elongate members  160  and  162  may comprise magnetic materials. 
     When the delivery device  150  has engaged a clip (such as clip  100  shown in  FIGS. 1A-1C ), the delivery device  150  may additionally be configured to actuate the clip between open and closed configurations. To move the clip  100  between its open and closed configurations, the engagement portion  154  may be selectively moved between its open and closed configurations, respectively. For example, as the engagement portion  154  is moved toward its closed configuration (such as shown in  FIG. 1B ), the distal portions  168  and  170  of the first and second elongate members  160  and  162  may be moved toward each other. This may apply a compressive force to the proximal ends  116  and  118  of first and second lever arms  102  and  104  of clip  100 , which may in turn cause the first and second lever arms  102  and  104  to rotate toward an open configuration. Conversely, moving the engagement portion  154  toward its open configuration may move the distal ends  168  and  170  of the first and second elongate members  160  and  162  away from each other. This may in turn allow the clip  100  to return to its closed configuration, such as shown in  FIG. 1A . 
     The engagement portion  154  may be moved between its open and closed configurations in any suitable manner. In some variations, the engagement portion  154  may be actuated by advancing or retracting the engagement portion  154  through the lumen  158  of cylindrical wall  156  of the delivery device  150 . Movement of the cylindrical wall  156  distally relative to the engagement portion  154  may cause the inner surface of cylindrical wall  156  at the distal end  174  to contact the outer surface of the first and second elongate members  160  and  162 . Further movement of the cylindrical wall  156  distally relative to the engagement portion  154  may then cause the cylindrical wall  156  to press against the outer surfaces of the first and second elongate members  160  and  162 , which may force the distance between the first and second elongate members  160  and  162  to stay substantially constant at the point where the first and second elongate members  160  and  162  contact the cylindrical wall  156 . As a result, the movement of the cylindrical wall  156  distally relative to the engagement portion  154  may push the engagement portion  154  toward a closed configuration. When the engagement portion  154  is moved toward a closed configuration, distal ends  168  and  170  of the first and second elongate members  160  and  162  may be moved toward each other, which in turn may press the distal ends  116  and  118  of the lever arms  102  and  104 , respectively, of the clip  100  toward each other. This may move the lever arms  102  and  104  of the clip  100  into an open configuration, as shown in  FIGS. 1B-1C . Conversely, when the cylindrical wall  156  is moved proximally relative to the engagement portion  154 , the cylindrical wall  156  may contact the engagement portion  154  at an increasingly proximal portion of the first and second elongate members  160  and  162 , which may allow the first elongate member  160  and the second elongate member  162  to move away from each other, returning to an open configuration, as shown in  FIG. 1A . This may release the pressure on the distal ends  116  and  118  of the first and second lever arms  102  and  104 , respectively, of the clip  100 , which in turn may cause the distal ends  116  and  118  of the first and second lever arms  102  and  104 , respectively, of clip  100  to return move away from each other and to a closed configuration, as shown in  FIG. 1A . 
     The delivery device  150  may be used to releasably attach a clip (such as clip  100  depicted in  FIGS. 1A-1C ) to tissue. The clip  100  may be engaged by the delivery device  150  (such as discussed in more detail herein), and the clip  100  and a distal portion of the delivery device  150  may be advanced into a patient (e.g., into a body cavity such as the abdominal cavity) through an access site (e.g., such as a laparoscopic port). Once the clip  100  is positioned within the body cavity, the delivery device  150  may be actuated to selectively move the clip  100  between its open and closed configurations in order to capture tissue between the lever arms of the clip  100 , thereby allowing the clip  100  to be releasably connected to tissue. Once the clip  100  holds tissue between the first lever arm  102  and the second lever arm  104 , the clip  100  may be controlled by the magnetic control assembly to manipulate the attached tissue, as discussed in more detail herein. The engagement portion  154  may then be disengaged from the clip  100  and removed from the anatomical cavity. If desirable, the delivery device  150  may subsequently reengage the clip  100  to disconnect the clip  100  from the tissue and/or reposition the clip  100 . 
       FIG. 2  shows another variation of a delivery device  200  that may be used to releasably engage one or more of the clips described here (such as the clip  100  described with respect to  FIGS. 1A-1C ). As shown there, the delivery device  200  may comprise a handle portion  202 , a shaft  204  extending from the handle portion  202 , and a distal engagement portion  206  at the distal end of the shaft  204 . 
     In some variations, a distal portion of the delivery device  200  may be configured for laparoscopic introduction into the body, such as described in more detail herein. In some of these variations, the delivery device  200  may be configured for advancement through a 10 mm laparoscopic port. In some instances, the shaft  200  and the distal engagement portion  206  of the delivery device  200  may be sized such that they may fit through a laparoscopic port when the distal engagement portion  206  is in the open configuration, the closed configuration, or either the open or closed configuration. In some of these variations, the largest width of the shaft  204  and the distal engagement portion  206  in a closed configuration may be less than or equal to about 10 mm, so that at least a portion of the delivery device  200  may be advanced through a 10 mm laparoscopic port when the distal engagement portion  206  is in a closed configuration. In some of these variations, the largest width of the shaft  204  and the distal engagement portion  206  in an open configuration may be less than or equal to about 10 mm, so that at least a portion of the delivery device  200  may be advanced through a 10 mm laparoscopic port when the distal engagement portion  206  is in an open configuration. In some of these variations, the distal engagement portion  206  may have an outer diameter less than or equal to about 4 mm in the open configuration, the closed configuration, or either the open or closed configuration. In these variations, it may be possible to advance the distal engagement portion  206  through a 10 mm laparoscopic port, and to further advance a second device having a diameter of about 5 mm or less through the port while the shaft  204  is positioned in the port. It should be appreciated that the shaft  204  may have any suitable diameter (e.g., between about 1 mm and about 15 mm, between about 5 mm and about 10 mm, or the like). The shaft  204  and distal engagement portion  206  may be formed from any suitable materials, such as one or more medical-grade, high-strength plastics or metals, such as stainless steel, cobalt chromium, PEEK, one or more nylons, polyimide, or the like, and/or may at least partially be formed from materials that may be attracted to a magnetic field, as described herein. 
     The distal engagement portion  206  may comprise a first arm  208  and a second arm  210  having distal ends  216  and  218 , respectively, which may be able to be actuated between an open configuration (as shown in  FIG. 2 ) and a closed configuration. In some variations, the first and second arms  208  and  210  may be able to be actuated between open and closed configurations by at least one of the first and second arms  208  and  210  being configured to flex toward or away from the other. In other variations, the first and second arms  208  and  210  may be able to be actuated between open and closed configurations by at least one of the first and second arms  208  and  210  being pivotably attached to the shaft  204 , such that it is configured to rotate relative to the shaft  204 . In the open configuration, the first and second arms  208  and  210  may be positioned away from each other to define a space between their distal ends  216  and  218 , such as shown in  FIG. 2 . In the closed configuration, the first and second arms  208  and  210  may be positioned closer toward each other to reduce or eliminate space between the distal portions  216  and  218  of the first and second arms  208  and  210 . 
     Generally, the handle  202  may comprise an actuation control mechanism  220  that may be manipulated by a user to controllably actuate the distal engagement portion  206 . The actuation control mechanism  220  may comprise any suitable configuration capable of actuating the distal engagement portion  206 , such as but not limited to a trigger, slider, knob, or the like. The delivery device  200  may comprise actuation elements within the shaft  204 , which may be connected to the actuation control mechanism  220  and/or the distal engagement portion  206 . A user may selectively open and close the arms  208  and  210 , as described herein, by moving the actuation control mechanism  220  between a first position and a second position. For example, when the actuation control mechanism  220  is in a first position (as shown in  FIG. 2 ), the distal engagement portion  206  may be in a closed position. Similarly, when the actuation control mechanism  220  is in a second position, the distal engagement portion  206  may be in an open position. In some variations, once the arms (such as arms  208  and  210 ) are in a closed configuration, the arms may lock in the closed configuration. In variations in which there is a locking mechanism, the locking mechanism may be disabled to allow the arms to return to the open configuration. 
     In the variation shown in  FIG. 2 , the delivery device  200  may comprise two pull wires  212  and  214  that run within the shaft  204  and connect on their proximal ends to the actuation control mechanism  220  of the delivery device  200 , and connect on their distal ends to the first and second arms  208  and  210 . In variations in which the delivery device  200  comprises pull wires (such as pull wires  212  and  214 ), the pull wires may be used in any manner to move the arms (such as arms  208  and  210 ) between the open and closed positions. In some variations, such as the variation shown in  FIG. 2 , moving the actuation control mechanism from a first position to a second position may apply tension to the pull wires, which may move the arms from the closed position to the open position. The delivery device  200  may be further configured such that moving the actuation control mechanism from a second position to a first position may return the device to the closed position (e.g., the arms may be biased towards the closed position, and moving the actuation control mechanism from a second position to a first position may release the tension in the pull wires, which may allow the arms to return to the closed position). 
     In other instances, moving the actuation control mechanism from a first position to a second position may apply tension to the pull wires, which may move the arms from the open position to the closed position. The delivery device  200  may in these instances be further configured such that moving the actuation control mechanism from a second position to a first position may return the device to the open position (e.g., the arms may be biased towards the open position, and moving the actuation control mechanism from a second position to a first position may release the tension in the pull wires, which may allow the arms to return to the to the open position). 
     Accordingly, to engage the clip  100 , a user may place the actuation control mechanism  220  in the second position (or an intermediate position between the first and second positions) to open (or partially open) the first and second arms  208  and  210 , and the user may the move the actuation control mechanism  220  toward the first position to close the arms around the clip  100 . The distal engagement portion  206  of the delivery device may be sized and configured to engage a clip (such as clip  100 ). In some variations, the distal portions  216  and  218  of the first and second arms  208  and  210  may comprise one or more features that may improve the ability of the delivery device  200  to reliably grip onto a clip (such as clip  100 ) and to exert a force on a clip, but need not comprise such features. For example, in variations in which the clip, such as clip  100 , comprises protrusions at the proximal ends of the lever arms (such as proximal ends  116  and  118  of lever arms  102  and  104  of clip  100 ), the distal engagement portion  206  may be configured to engage the protrusions. More specifically, if the protrusions comprise outwardly facing hemispherical protrusions  120  and  122 , as in clip  100  of  FIGS. 1A-1C , the distal engagement portion  206  may comprise concave grips to engage the protrusions  120  and  122 , respectively. 
     The actuation control mechanism  220  may be further moved toward the first position to press the clip  100  into an open configuration. The user may then manipulate the clip  100 , using the delivery device  200 , to position tissue between the first  102  and second  104  lever arms of the clip  100 . With the tissue positioned between the arms, the actuation control mechanism may be moved back toward the second position to first allow the clip  100  to close, and then to release the clip  100  from the delivery device  200 . 
       FIGS. 3A-3C  depict another variation of a system in which the grasper comprises a clip. As shown there, the system may comprise a clip  300  and a delivery device  340 . It should be appreciated that the clip  300  may be actuated and delivered using any suitable delivery device (such as those described here) and the delivery device  340  may be used to actuate and/or deliver any suitable grasper (such as those described here). Specifically,  FIGS. 3A-3B  show perspective views of the clip  300  and the delivery device  340 . The clip  300  may comprise a coupling element  380 , which may allow it to be releasably coupled to a delivery device  340 . When the clip  300  is coupled to the delivery device  340 , the delivery device  340  may actuate the clip  300  to connect the clip  300  to tissue or detach the grasper therefrom. The clip  300  and the delivery device  340  will each be discussed in more detail herein. 
     In some variations, the delivery device  340  and the clip  300  may be configured for laparoscopic introduction into the body, such as discussed herein. In these variations, the clip  300  may be sized such that it may be advanced through a laparoscopic port. In some instances, the clip  300  may be sized such that it may fit through a laparoscopic port when the clip  300  is in the open configuration, in the closed configuration, or in either the open or closed configuration. In some of these variations, the largest width of the clip  300  in a closed configuration may be less than or equal to about 10 mm, so that the clip  100  may be advanced through a 10 mm laparoscopic port when the clip is in the closed configuration. Similarly, a distal portion of the delivery device  340  may also be sized such that it may fit through a laparoscopic port. In some variations, the delivery device  340  may be configured such that the distal portion of the delivery device  340  may have a diameter less than or equal to about 10 mm. The clip  300  and delivery device  340  may be formed from any suitable materials, such as one or more of medical grade, high-strength plastics or metals, such as stainless steel, cobalt chromium, PEEK, one or more nylons, polyimide, or the like, and/or may be at least partially formed from materials that may be attracted to a magnetic field, as described herein. 
     The clip  300  illustrated in  FIGS. 3A-3C  may be configured to releasably pinch or grip tissue in a similar manner as the clip  100  described with respect to  FIGS. 1A-1C . As shown in  FIGS. 3A-3C , the clip  300  may comprise a first lever arm  302  and a second lever arm  304  attached at a pivot joint  306 . The first and second lever arms  302  and  304  may be rotated relative to each other about pivot joint  306  to actuate the clip  300  between closed and open configurations to releasably connect the clip  300  to tissue or release the clip  300  from tissue, respectively. In the open configuration, the distal portions  308  and  310  of first and second lever arms  302  and  304 , respectively, may be rotationally positioned away from each other to define a space between the distal portions  308  and  310  of the first and second lever arms  302  and  304 , such as shown in  FIG. 3B . Similarly, when the clip  300  is in a closed configuration, the distal portions  308  and  310  of the first and second lever arms  302  and  304  may be rotationally biased toward each other to reduce or eliminate space between the distal portions  308  and  310  of the first and second lever arms  302  and  304 . While the distal portions  308  and  310  of the first and second lever arms  302  and  304  are shown in  FIGS. 3A and 3C  as contacting each other, it should be appreciated that when clip  300  is connected to tissue, tissue positioned between the first and second lever arms  302  and  304  may prevent the distal portion  308  of the first lever arm  302  from contacting the distal portion  310  of the second lever are 304 when the clip is placed in the closed configuration. In some variations, the distal portions  308  and  310  of the first and second lever arm  302  and  304  may be rotationally biased toward each other. For example, in some variations the clip  300  may comprise a spring, such as a torsional spring, which may spring-bias the distal portions  308  and  310  of the first and second lever arms  302  and  304 , respectively, toward each other, which in turn may bias the clip  300  into a closed position. The bias of the lever arms toward the closed configuration may act to hold tissue positioned between the distal portions  308  and  310  of the first lever arm  302  and the second lever arm  304 . 
     The distal portions  308  and  310  of first and second lever arms  302  and  304 , respectively, may comprise one or more features which may promote engagement with tissue, but need not. In some variations, the inner surfaces  312  and/or  314  of the distal portions  308  and  310 , respectively, may be roughened or texturized, which may help to reduce slipping between the lever arms and tissue. Additionally or alternatively, the inner surfaces  312  and/or  314  may comprise teeth or ridges  316  (such as shown in  FIG. 3B ) or other projections which may facilitate engagement of the first and second lever arms  302  and  304  with tissue. In some variations of the clip described here, the clip may comprise one or more coatings that may help to smooth discontinuities in the contours of the clip and may act to provide one or more atraumatic surfaces of the clip. The one or more coatings may comprise silicone, urethane, one or more nylon blends, polyethylenes, fluoropolymers, combinations thereof and the like. 
     The proximal ends  316  and  318  of lever arms  302  and  304 , respectively, may be sized and configured to be engaged by a delivery device (such as delivery device  340 , as described in more detail herein) to open the clip in order to engage tissue In some instances, as shown in  FIGS. 3A-3C , the proximal ends  316  and  318  of lever arms  302  and  304 , respectively, of the clip  300  have a tapered section  320 , such that the overall diameter of the clip  300  may taper along the tapered section  320 . This may facilitate actuation of the clip  300  by the delivery device  340 , as described herein. In some instances, an external grasping device may also be used to actuate the clip  300  by gripping and compressing the tapered section  320 . 
     Generally, at least a portion of the clip  300  described here may be formed from one or more materials which may be attracted to a magnetic field, as described in more detail herein, but need not be. The materials may include one or more magnetic or ferromagnetic materials, such as, for example, stainless steel, iron, cobalt, nickel, neodymium iron boron, samarium cobalt, alnico, ceramic ferrite, alloys thereof and/or combinations thereof. In variations in which the materials include steel alloys, the steel alloys may be in a martensitic state. In some variations, coldworking may be used to improve the magnetic permeability of the clip  300 , for instance during the machining process. Having at least a portion of the clip  300  formed from one or more metallic or magnetic materials that may be attracted to a magnetic field may allow the clip  300  to be manipulated by a magnetic control assembly, as will be discussed in more detail herein. In some variations, the proximal ends of the clip  300  may comprise magnetic or ferromagnetic materials to facilitate engagement by the delivery device (as described in more detail herein), but need not. In some variations, the at least a portion of the clip  300  formed from one or more materials which may be attracted to a magnetic field may be part of the coupling element  380  described below; in other variations, this magnetic portion may be distinct from the coupling element  380 . 
     As mentioned above, the clip  300  may also comprise a coupling element  380 . The coupling element  380  may facilitate engagement of the clip  300  to a delivery device (such as the delivery device  340 ), and may further facilitate actuation of the clip  300  between open and closed configurations, as described in detail herein. As shown in  FIGS. 3A-3C , the coupling element may comprise a linking body  382  attached to the remainder of the clip  300  via a coupling rod  384 . The linking body  382  may connect the clip  300  to the delivery device  340 , as described in detail herein. In some variations, the linking body  382  may be configured to fit slidably within the delivery device  340 . While the linking body  382  is shown as having a cylindrical shape in the variation shown in  FIGS. 3A-3C , it should be appreciated that the linking body  382  may have other shapes. In some variations, such as the variation shown in  FIGS. 3A-3C , the coupling rod  384  may attach to the clip  300  at or near pivot joint  306 . The coupling rod  384  may be configured such that it does not interfere with the movement of lever arms  302  and  304  into an open configuration. For instance, as shown in  FIGS. 3A-3C , the coupling rod  384  may comprise a rigid rod sized such that the first and second lever arms  302  and  304  do not contact the coupling rod  382  when the clip  300  is in an open configuration. At least a portion of the linking body  382  may comprise one or more materials which may be attracted to a magnetic field, which may facilitate temporary connection of the linking body  382  to a delivery device. These materials may include one or more magnetic or ferromagnetic materials, such as, for example, stainless steel, iron, cobalt, nickel, neodymium iron boron, samarium cobalt, alnico, ceramic ferrite, alloys thereof and/or combinations thereof. 
     Turning to the variation of the delivery device  340  shown in  FIGS. 3A-3C , the delivery device  340  may comprise an outer sheath  342  having a lumen  350 . At least a portion of the tapered section  320  of proximal ends  316  and  318  of the lever arms  302  and  304  may have an overall diameter that is less than that of the lumen  350  of outer sheath  342 , which may allow at least a portion of the tapered section  320  to fit within the lumen  350 . The clip  300  may be actuated between closed and open configurations by moving the clip  300  into and out of the lumen  350 , respectively. As the clip  300  is moved into the lumen  350 , the outer surfaces of the proximal ends  316  and  318  of first and second lever arms  302  and  304  may contact the inner surface of outer sheath  342 . Once the outer surfaces of the proximal ends  316  and  318  contact the outer sheath  342 , further movement of the clip  300  into the lumen  350  of outer sheath  342  may cause the proximal ends  316  and  318  to be pushed toward each other due to the constrained diameter of lumen  350 . As the proximal ends  316  and  318  are pushed toward each other, the distal portions  308  and  310  of first and second lever arms  302  and  304  may be rotated away from each other, which may move the clip  300  into an open configuration, as shown in  FIG. 3B . Conversely, movement of the clip  300  out of the lumen  350  frees the proximal ends  316  and  318  of first and second lever arms  302  and  304  from the constraint of the outer sheath  342 . In variations in which the distal ends  308  and  310  of the first and second lever arms  302  and  304  are rotationally biased toward each other, this bias may help to return the clip  300  to the closed position once the proximal ends  316  and  318  of the first and second lever arms  302  and  304  are freed from the constraint of the outer sheath  342 , as shown in  FIG. 3A . 
     The clip  300  may be moved into and out of the lumen  350  of outer sheath  342  using any suitable mechanism. In the variation of the delivery device  340  shown in  FIGS. 3A-3C , the clip  300  may be moved into and out of the lumen by an actuation rod  346  located slidably within lumen  350  of outer sheath  342 . Actuation rod  346  may releasably engage coupling element  380  of the clip  300  by engaging with linking body  382 . In some variations, the actuation rod may comprise one or more magnetic and/or ferromagnetic materials in at least its distal end  349 , and thus actuation rod  346  may releasably engage linking body  382  via a magnetic attractive force when the actuation rod  346  and linking body  382  are in proximity to each other. When the actuation rod  346  and linking body  382  are engaged, retraction and advancement of the actuation rod  346  within the lumen  350  of outer sheath  342  may move the clip into and out of the lumen  350 , which may in turn move the clip  300  between open and closed configurations, such as described in detail herein. 
     In order for releasable engagement of the actuation rod  346  and linking body  382 , delivery device  340  may further comprise a depth stop that may prevent linking body  382  from moving within lumen  350  of outer sheath  342  beyond a certain point. Thus, if actuation rod  346  is moved beyond the depth stop, the force from the depth stop on the linking body  342  may overcome the engagement force connecting the actuation rod  346  and linking body  342  (e.g., magnetic attractive force), and actuation rod  346  may be disengaged from the linking body  382 . In some variations, as shown in  FIGS. 3A-3C , the depth stop may comprise an inner sheath  344 . The inner sheath  344  may be slidably located within the outer sheath  342 , and the actuation rod  346  may be slidably located within the inner sheath  344 . The outer and inner sheaths  342  and  344  may be sized and configured such that the linking body  382  of the coupling element  380  may fit within the outer sheaths  342 , but may be prevented from entering the inner sheath  344 . The outer sheath  342 , inner search  344 , actuation rod  346 , and linking body  382  may have a first configuration for engaging the linking body  382  with the actuation rod  346 , a second configuration for moving the clip  300  into an open configuration, and a third configuration to release the linking body  382  from the actuation rod  346 . In the first configuration for engaging the linking body  382  with the actuation rod  346 , the distal end  349  of the actuation rod  346  may be aligned with the distal end  348  of the inner sheath  344 , which may be located proximally to the distal end  346  of the outer sheath  342 . The linking body  382  of clip  300  may be located within the outer sheath  342  adjacent to the distal ends  348  and  349  of inner sheath  344  and actuation rod  346 , respectively, but such that the remainder of the clip  300  is located outside of the outer sheath  342 . In other variations, the distal end  348  of inner sheath  344  may be located distally to the distal end  349  of actuation rod  346 . In the second configuration, shown in  FIG. 3B , the actuation rod  346 , inner sheath  344 , and clip  300  may be retracted within the outer sheath  342  relative to the first configuration, which may move the clip  300  into an open configuration, as described in detail herein. In the third configuration, the distal end  349  of the actuation rod  346  may be located proximally to the distal end  348  of the inner sheath  344 , while the linking body  382  is located distally to the distal end  348  of the inner sheath  344 , disengaging the actuation rod  346  and linking body  382 . The positions of the inner shaft  344  and the actuation rod  346  may be controlled by any suitable mechanism or mechanisms, such as one or more trigger mechanisms on a handle portion (not shown) of the delivery device  340 . 
     Thus, the system of  FIGS. 3A-3C  may be used to releasably attach the clip  300  to tissue. The clip  300  may be engaged by the delivery device  340  by the actuation rod  346  engaging with the linking body  382  of the coupling element  380 . If the linking body  382  and the actuation rod  346  are engaged (e.g., held together by a magnetic attractive force), retraction and advancement of the actuation rod  349  and the clip  300  relative to the outer sheath may cause the delivery device  340  to actuate the clip  300  between open and closed configurations, respectively. As mentioned above, the proximal ends  316  and  318  of lever arms  302  and  304 , respectively, of the clip  300  may have a tapered section  320 . At least a portion of the tapered section  320  may have a diameter less than that of the lumen  350  of the outer sheath  342  and at least a portion may have a diameter greater than that of the outer sheath  342 . Thus, when the clip  300  is coupled to the delivery device  340  via the coupling element  380 , the clip  300  may be actuated between closed and open configurations by moving the actuation rod  346  proximally relative to the outer cylinder  342 , which may cause the proximal ends  316  and  318  of lever arms  302  and  304  to be pushed toward each other due to the constrained diameter provided by the outer cylinder  342 , as described herein. As the proximal ends  316  and  318  of lever arms  302  and  304  are pushed toward each other, the distal portions  308  and  310  of the lever arms  302  and  304  may be moved into an open configuration. 
     The clip  300  can then be releasably attached to tissue by moving the actuation rod distally relative to the outer cylinder  342 , which may release the constraint on the proximal ends  316  and  318  of lever arms  302  and  304 , which in turn may allow the distal ends  316  and  318  of lever arms  302  and  304  to be moved into a closed configuration. In variations in which the first lever arm  302  and the second lever arm  304  are rotationally biased toward each other, this bias may help to return the clip  300  to the closed position. Additionally, the bias of the lever arms toward the closed configuration may act to hold tissue positioned between the first lever arm  302  and the second lever arm  304 . Once the clip  300  holds tissue between the first lever arm  302  and the second lever arm  304 , the clip  300  may be controlled by the magnetic control assembly to manipulate the attached tissue, as described in more detail herein. 
     The clip  300  may then be decoupled from the delivery device  340 . The clip  300  may be decoupled from the delivery device  340  by withdrawing the actuation rod  346  distally relative to the inner sheath  344  to a retracted position, as shown in  FIG. 3C . As the actuation rod  346  is pulled proximally relative to the inner sheath  344 , the clip  300  may be pulled in contact with the inner sheath  344 , such as discussed herein. This engagement may prevent further proximal movement of the clip  300 , and thus withdrawal of the actuation rod  346  proximally relative to the inner sheath  344  may increase the distance between linking body  382  of coupling element  380  and the actuation rod  346  of the delivery device  340 . Because the force applied by a magnet decreases as a function of the distance from the magnet, moving the actuation rod  346  to a retracted position may decrease the magnetic attractive force felt by the linking body  382  of the coupling element  380 . Eventually, the attractive force may be sufficiently diminished such that the coupling element  380  may decouple from the delivery device  340 . In some instances, the outer sheath  342  may be withdrawn past the inner sheath  344 , or the inner sheath  344  may be advanced past outer sheath, such that the diminished force allows the clip  300  to fall away from the delivery device  340 . Conversely, if a portion of the clip  300  remains in the outer sheath  342 , an additional force (e.g., gravity, resistance provided by the grasped tissue) may overcome the attractive force and pull the clip  300  out of the outer sheath  342 . If desirable, the delivery device  340  may subsequently reengage the clip  300  to disconnect the clip  300  from tissue and/or reposition the clip  300 . 
     Although  FIGS. 3A-3C  show an actuation rod  346  configured to magnetically engage the clip  300 , the actuation rod may be configured to engage the clip in any suitable manner. In some variations, for instance, the actuation rod may be configured to mechanically engage the clip. For example,  FIGS. 3D-3E  show cross-sectional side views of another variation of a system comprising a delivery device  360  and a clip  330 . The clip  330  is similar to the clip of  FIGS. 3A-3C  (with identical components labeled as in  FIGS. 3A-3C ), but with different mechanisms for engagement by the actuation rod. The delivery device  360  may comprise an actuation rod, outer sheath, and in some variations an inner receiving cylinder. 
     In the variation shown in  FIGS. 3D-3E , the delivery device  360  may comprise a shaft  362  and a control rod  364 . The clip  330  may comprise a coupling element  390  having a receiving cylinder  392  which may be configured fit slidably within shaft  362  of the delivery device  360 . The actuation rod  364  of the delivery device  360  may have a coupling element at its distal end, which mates with the locking mechanism of the clip  300 . The coupling element and locking mechanism may have any design that allows the actuation rod  364  to be releasably coupled to the receiving cylinder  392 . In the variation shown in  FIGS. 3D-3E , the coupling element  390  may comprise a receiving cylinder  392  having a locking mechanism. The locking mechanism may comprise two spring-loaded triangular elements  396  located across from each other on the interior of receiving cylinder  392 . The coupling portion of actuation rod  364  may comprise two corresponding triangular recesses  366  in the surface of control rod  364 . When the actuation rod  364  is advanced distally within receiving cylinder  392 , it may initially push the spring-loaded triangular elements  396  outward, and then the triangular elements  396  may snap into the recesses  366  of the actuation rod  364 . When the triangular elements  396  are snapped into the recesses  366  of the actuation rod  364 , the control rod  364  may resist withdrawal from the receiving cylinder  392 , which may temporarily couple the coupling element  390 , and in turn the clip  300 , to the delivery device  360 . In some variations, the distal end of actuation rod  364  may have a slightly tapered shape, so as to facilitate insertion into the open-ended cylinder  392 . 
     The delivery device  362  may comprise a release mechanism, such as a button or pull wire, which allows the locking mechanism to be released, which in turn may release the actuation rod  364  from within the receiving cylinder  392 , releasing the coupling element  390  and thus the clip  300  from the delivery device  360 , as shown in  FIG. 3D . In some variations, the delivery device  362  may comprise an inner sheath that may allow the actuation rod  364  to be withdrawn relative to the receiving cylinder  392  to overcome the locking force provided by the spring-loaded triangular elements  396 . When coupled to the clip  330 , the system of  FIGS. 3D-3E  may be used to releasably attach, decouple, and/or reengage the clip  330  to tissue by retraction and advancement of the actuation rod  364  relative to the outer sheath  364 , in a similar manner described with respect to  FIGS. 3A-3C . 
       FIG. 3F  shows another variation of a coupling portion and locking mechanism. Clip  331  is similar to the clip of  FIGS. 3A-3C  and  FIGS. 3D-E  (with identical components labeled as in  FIGS. 3A-3E ), but with a different mechanism for engagement by the actuation rod. The delivery device  361  may comprise an actuation rod, outer sheath, and an inner receiving cylinder. The locking mechanism of the coupling element  391  of clip  331  may comprise a compression spring  398  attached to the inside of the distal end of the receiving cylinder  393  and one or more substantially J-shaped tracks  399  extending from the inner lumen of the receiving cylinder  393  at least partially through the wall of the receiving cylinder  393 . The receiving cylinder  393  of the coupling element  391  may be sized to fit slidably within outer shaft  363  of delivery device  361 . The coupling portion of actuation rod  365  may comprise one or more tabs or protrusions  368  extending from a side surface of the actuation rod  365 . Each tab/protrusion may be sized and shaped to fit within a corresponding track  399 . When the actuation rod  364  is advanced distally within receiving cylinder  393 , it may compress the compression spring  398 , while the tab(s) or protrusion(s)  368  may follow the track  399 . As the tab(s) or protrusion(s)  368  follow the track  399 , they may move distally along the straight portion  389  of the cut-out(s) or recess(es)  399 . The tab(s) or protrusion(s)  368  may then move around the curved portion  387  of the cut-out(s) or recess(es)  399 . After having traveled proximally around the curve portion  387  of the cut-out(s) or recess(es)  399 , the tab(s) or protrusion(s)  368  may be held in place by the spring  398 , thus locking the actuation rod  365  into the receiving cylinder  393 . In some variations, the distal end of actuation rod  365  may have a slightly tapered shape, so as to facilitate insertion into the receiving cylinder  393 . The delivery device  361  may comprise a release mechanism, such as a button or pull wire, which may allow the locking mechanism to be released. In some variations, the button or pull wire may release the locking mechanism by withdrawing the tab(s) or protrusion(s) into the actuation rod  365 . In other variations, the locking mechanism may be released by rotating the actuation rod  365  relative to the receiving cylinder  393 . Releasing the locking mechanism may in turn may release the actuation rod  365  from within the receiving cylinder  393 , which may release the coupling element  391  and thus the clip  300  from the delivery device  361 . When coupled to the clip  331 , the system of  FIG. 3F  may be used to releasably attach, decouple, and/or reengage the clip  331  to tissue by retraction and advancement of the actuation rod  364  relative to the outer sheath  365 , in a similar manner described with respect to  FIGS. 3A-3C . 
       FIGS. 4A-4B  depict another variation of a system as described here in which the grasper comprises a clip. Specifically,  FIGS. 4A-4B  show perspective and side views, respectively, of a system comprising a clip  400  and delivery device  450 . The clip  400  may be releasably coupled to the delivery device  450  (as shown in  FIG. 4B ), and the delivery device  450  may actuate the clip  400  between open and closed configurations to connect the clip  400  to tissue or detach the grasper therefrom, respectively. 
     As in the other variations discussed herein, the delivery device  450  and the clip  400  may be configured for laparoscopic introduction into the body. In these variations, the clip  400  may be sized such that it may be advanced through a laparoscopic port. In some instances, the clip  400  may be sized such that it may fit through a laparoscopic port when the clip  400  is in the open configuration, the closed configuration, or either the open or closed configuration. In some of these variations, the largest width of the clip  400  in a closed configuration may be less than or equal to about 10 mm, so that the clip  400  may be advanced through a 10 mm laparoscopic port when the clip is in the closed configuration. Similarly, a distal portion of the delivery device  450  may also be sized such that it may fit through a laparoscopic port. In some variations, the delivery device  450  may be configured such that the distal portion of the delivery device  450  (e.g., actuation rod  452 , as discussed in more detail herein) may have a diameter less than or equal to about 10 mm. The clip  400  and delivery device  450  may be formed from any suitable materials, such as one or more of medical grade, high-strength plastics or metals, such as stainless steel, cobalt chromium, PEEK, one or more nylons, polyimide, or the like, and/or may at least partially be formed from magnetic materials, as described herein. 
       FIG. 4C  shows an enlarged side view of the clip  400 . As shown there, the clip  400  may comprise a first arm  402  and a second arm  404  attached at pivot joint  406 . The first and second arms  402  and  404  may have proximal portions  408  and  410 , respectively, and distal portions  412  and  414 , respectively, which may be configured to cross across pivot joint  406  such that rotation of the proximal portions  408  and  410  away from each other may correspond with rotation of the distal portions  412  and  414  away from each other, and similarly, rotation of the proximal portions  408  and  410  toward each other may correspond with rotation of the distal portions  412  and  414  toward each other. The clip  400  may be actuated between closed and open configurations to releasably connect the clip  400  to tissue or release the clip  400  from tissue, respectively. In the open configuration, the distal portions  412  and  414  of the first and second arms  402  and  404  may be rotationally positioned away from each other to define a space between the distal portions  412  and  414  of the first and second arms  402  and  404 , such as shown in  FIG. 4B . Similarly, when the clip  400  is in a closed configuration, the distal portions  412  and  414  of the first and second arms  402  and  404  may be rotationally biased toward each other to reduce or eliminate space between the distal portions  412  and  414  of the first and second arms  402  and  404 . While the distal portions  412  and  414  of the first and second arms  402  and  404  are shown in  FIGS. 4A and 4C  as contacting each other, it should be appreciated that when clip  400  is connected to tissue, tissue positioned between the first and second arms  402  and  404  may prevent the distal portion  412  of the first arm  402  from contacting the distal portion  414  of the second arm  404  when the clip  400  is placed in the closed configuration. In some variations, the distal portions  412  and  414  of first and second arms  402  and  404  may be rotationally biased toward each other. For example, in some variations the clip  400  may comprise a spring, such as a torsional spring, which may spring-bias the distal portions  412  and  414  of the first and second arms  402  and  404  toward each other, which may in turn bias the clip  400  into a closed position. The bias toward the closed configuration may act to hold tissue positioned between the distal portions  412  and  414  of the first and second arms  402  and  404 . 
     The distal portions  412  and  414  of the first and second arms  402  and  404 , respectively, may comprise one or more features that may promote engagement with tissue, but need not. In some variations, the inner surfaces  416  and/or  418  of the distal portions  412  and  414 , respectively, may be roughened or texturized, which may help to reduce slipping between the arms and tissue. Additionally or alternatively, the inner surfaces  416  and/or  418  may comprise teeth or ridges, or other projections that may facilitate engagement of the first and second arms  402  and  404  with tissue. In some variations of the clip described here, the clip may comprise one or more coatings that may help to smooth discontinuities in the contours of the clip and may act to provide one or more atraumatic surfaces of the clip. The one or more coatings may comprise silicone, urethane, one or more nylon blends, polyethylenes, fluoropolymers, combinations thereof, and the like. 
     Generally, at least a portion of the clip  400  described here may be formed from one or more materials which may be attracted to a magnetic field, as described in more detail herein, but need not be. The materials may include one or more magnetic or ferromagnetic materials, such as, for example, stainless steel, iron, cobalt, nickel, neodymium iron boron, samarium cobalt, alnico, ceramic ferrite, alloys thereof and/or combinations thereof. In variations in which the materials include steel alloys, the steel alloys may be in a martensitic state. In some variations, coldworking may be used to improve the magnetic permeability of the clip  400 , for instance during the machining process. Having at least a portion of the clip  400  formed from one or more metallic or magnetic materials that may be attracted to a magnetic field may allow the clip  400  to be manipulated by a magnetic control assembly, as will be discussed in more detail herein. In some variations, the proximal ends of the clip  400  may comprise magnetic or ferromagnetic materials to facilitate engagement by the delivery device (as described in more detail herein), but need not. In some variations, the at least a portion of the clip  400  formed from one or more materials which may be attracted to a magnetic field may be part of the coupling element  420  described herein; in other variations, this magnetic portion may be distinct from the coupling element  420 . 
     As mentioned above, the clip  400  may further comprise a coupling element  420 . The coupling element  420  may facilitate engagement of the clip  400  to a delivery device (such as the delivery device  450 ), and may further facilitate actuation of the clip  400  between open and closed configurations, as described in detail herein. As shown in  FIGS. 4A-4C , the coupling element  420  may be configured to facilitate temporary coupling between the clip  400  and a delivery device. Generally, the coupling element  420  may comprise a body  422  and a bore  424  extending therethrough. In the variation shown in  FIGS. 4A-4C , the body  422  may be shaped as a tapered cylinder, although it should be appreciated that the body may have any suitable shape (e.g., a cylinder, a box shape, or the like). Additionally, while the bore  424  is shown in  FIGS. 4A-4C  extending along a central axis of the body  422 , it should be appreciated that in some variations the bore may be offset from the central axis of the body  422 . 
     Generally, the bore may be configured to house the proximal ends  408  and  410  of the lever arms  402  and  404  to couple the coupling element  420  to the arms. The bore  424  may be sized to accommodate the proximal ends  408  and  410  of the lever arms  402  and  404 , and a distal portion of the bore  424  may be sized such that remainder of the clip (i.e., the first and second lever arms  402  and  404 ) may be prevented from disengaging the coupling element  420  during use of the clip  400 . Additionally, in some variations the bore may comprise a threaded portion  426 , which may engage a portion of a delivery device, as will be described in more detail herein. Additionally or alternatively, the bore  424  may comprise a funnel portion  428  at a proximal end of the bore  424 , such that the diameter of the bore  424  may increase from a distal end of a funnel portion  428  to a proximal end of the funnel portion  428 . The larger diameter at the proximal end of the funnel portion may provide a larger entrance to receive a portion of a delivery device, and the decreasing diameter towards the distal end of the funnel portion may guide the received portion of the delivery device toward the remainder of the bore  424 . In some variations, at least a portion of the funnel portion  428  may have a non-circular cross-section, which may facilitate actuation of the clip  400 , as will be discussed in more detail herein. 
     As mentioned above, the coupling element  420  may be configured to facilitate temporary coupling between the clip  400  and a delivery device. For example,  FIGS. 4A and 4B  depict variations of a delivery device  450 , which may be configured to couple to and actuate the clip  400 . As shown there, the delivery device  450  shown in  FIGS. 4A-4B  may comprise an outer sheath  458  and an actuation rod  452  positioned at least partially within and slidable relative to the outer sheath  458 . As shown there, the actuation rod  452  may comprise a threaded section  456 , which may engage the threaded portion  426  of the bore. To do so, the actuation rod  452  may be advanced into the bore  424  of the coupling element  420 . In some variations, the actuation rod  452  may have a tapered distal end  454 , which may allow the actuation rod to more easily enter the bore. This may provide particular utility in instances where the actuation rod  452  is introduced to the bore  424  when the clip  400  is positioned within the body. Similarly, when the bore  424  comprises a funnel portion  428 , the funnel portion  428  may help to guide the actuation rod  452  into the bore  424 . 
     When the threaded portion  456  of the actuation rod  452  reaches the threaded portion  426  of the bore  424 , the actuation rod  452  may be rotated relative to the coupling element  420  to screw the threaded portion  456  of the actuation rod into the threaded portion  426  of the bore  424  to engage the actuation rod  452  and the bore  424 . When the threaded portions  426  and  456  of the bore  424  and the actuation rod  452 , respectively, are engaged, rotation of the actuation rod  452  in a first direction relative to the coupling element  420  may advance the actuation rod  452  along the bore  424 . Conversely, rotation of the actuation rod  452  in an opposite direction relative to the coupling element  420  may retract the actuation rod  452  relative to the bore  424 . 
     When the actuation rod  452  engages the coupling element  424  as discussed herein, it may be desirable to hold or otherwise constrain the coupling element  424  such that rotation of the actuation rod  452  does not cause the clip  400  to rotate with the actuation rod  452 . If the clip  400  is free to rotate with the actuation rod  452 , the actuation rod  452  may not rotate relative to the clip  400 , and thus may not be able to advance or withdraw relative to the clip  400 . Accordingly, in some variations, the outer sheath  458  may comprise one or more projections  460  extending from a distal end of the outer sheath  458 . The one or more projections  460  may be configured to engage a portion of the coupling element  420 , such that the engagement between the one or more projections  460  and the coupling element  420  prevents rotation between the outer sheath  458  and the coupling element  420 . For example, in variations where a portion of the bore  424  of the coupling element  420  comprises a non-circular cross-sectional shape (e.g., a square-shaped portion of a funnel portion  428 ), the outer sheath  458  may comprise a projection  460  having a corresponding shape (e.g., a square-shaped projection) that is configured to fit within the bore  424  and prevent rotation between the bore  424  and the projection  460 . In these instances, the outer sheath may be advanced such that the projection  460  engages the coupling element  420 . Since this engagement may prevent rotation between the outer sheath  458  and the clip  400 , rotation of the actuation rod  452  relative to the outer sheath  458  may also result in rotation of the actuation rod  452  relative to the clip  400 , which may cause threading between the actuation rod and the bore, as discussed herein. 
     The delivery device  450  may also be configured to actuate the clip  400 . As mentioned above, rotation of the actuation rod  452  relative to the clip  400  may advance the actuation rod  452  through the bore  424  of the coupling element  420 . As the actuation rod  452  is advanced, the tapered distal end  454  of the actuation rod  452  may be selectively advanced between the distal portions  408  and  410  of the first and second lever arms  402  and  404 . Further advancement of the actuation rod  452  may rotate the proximal ends  407  and  409  of the first and second arms  402  and  404  away from each other, which may move the clip  400  into an open configuration, as shown in  FIG. 4B  and discussed herein. Conversely, when the actuation rod  452  is selectively retracted proximally relative to the clip  400  by rotation in the opposite direction relative to the threaded portion  426  of bore  424 , the first and second lever arms  402  and  404  may rotate to return to a closed configuration, as shown in  FIGS. 4A and 4C , allowing the clip  400  to be releasably connected to tissue. The actuation rod  452  may be rotated directly by the user, or the rotation may be actuated by any suitable mechanism, such as one controlled by the user at a remote proximal location via a handle or other interface. Once the clip  400  holds tissue between the first arm  402  and the second arm  404 , the clip  400  may be controlled by the magnetic control assembly to manipulate the attached tissue. The delivery device  450  may be disengaged from the clip  400  and removed from the anatomical cavity. If desirable, the delivery device  450  may subsequently reengage the clip  400  to disconnect the clip  400  from the tissue and/or reposition the clip  400 . 
       FIGS. 1A-11B and 12A-12B  depict other variations of systems as described here in which the grasper comprises a clip. Specifically,  FIGS. 11A-11B  show perspective views of a system comprising a clip  1100  and a delivery device  1150 , and  FIGS. 12A-12B  show perspective views of a system comprising a clip  1200  and a delivery device  1250 . The clips  1100 ,  1200  may be releasably coupled to the delivery devices  1150 ,  1250  (as shown in  FIGS. 11A-11B and 12A-12B ), and the clips  1100 ,  1200  may be actuated between closed ( FIGS. 11A and 12A ) and open ( FIGS. 11B and 12B ) configurations by the delivery devices  1150 ,  1250  or by a separate device, as described in more detail herein. 
     As in the other variations discussed herein, the delivery devices  1150 ,  1250  and the clips  1100 ,  1200  may be configured for laparoscopic introduction into the body. In these variations, the clips  1100 ,  1200  may be sized such that they may be advanced through a laparoscopic port. In some instances, the clips  1100 ,  1200  may be sized such that they may fit through a laparoscopic port when the clips  1100 ,  1200  are in an open configuration, closed configuration, or either the open or closed configurations. In some of these variations, the largest width of the clips  1100 ,  1200  in a closed configuration may be less than or equal to about 10 mm, so that the clips  1100 ,  1200  may be advanced through a 10 mm laparoscopic port when the clips are in a closed configuration. Similarly, distal portions of the delivery devices  1150 ,  1250  may also be sized such that they may fit through a laparoscopic port. In some variations, the delivery devices  1150 ,  1250  may be configured such that the distal portions of the delivery devices  1150 ,  1250  may have diameters less than or equal to about 10 mm. The clips  1100 ,  1200  and delivery devices  1150 ,  1250  may be formed from any suitable materials, such as one or more of medical grade, high-strength plastics or metals, such as stainless steel, cobalt chromium. PEEK, one or more nylons, polyimide, or the like, and/or may at least partially be formed from magnetic materials, as described herein. 
     As shown in  FIGS. 11A-11B and 12A-12B , the clips  1100 ,  1200  may comprise linkage assemblies  1120 ,  1220 . Each linkage assembly may comprise a series of struts connected by pivot joints, such that force applied to one or more struts may cause the clip to move between the open and closed configurations. In some variations, such as the one shown in  FIGS. 11A-11B , collapsing the linkage assembly (i.e., moving the struts toward each other by rotating them about the pivot joints) may cause the clip  1100  to move from a closed configuration to an open configuration, while expanding the linkage assembly (i.e., moving the struts away from each other by rotating them about the pivot joints) may cause the clip  1100  to move from an open configuration to a closed configuration. In other variations, such as the one shown in  FIGS. 12A-12B , collapsing the linkage assembly (i.e., moving the struts toward each other by rotating them about the pivot joints) may cause the clip to move from an open configuration to a closed configuration. Conversely, expanding the linkage assembly (i.e., moving the struts away from each other by rotating them about the pivot joints) may cause the clip to move from a closed configuration to an open configuration. 
     It should be appreciated that force need not be applied to all struts in the linkage assembly in order to move the clip between the open and closed configurations; rather, force applied to a subset of the struts (e.g., one or two struts, such as two opposing struts, or at one or two pivot joints, such as two opposing pivot joints) may cause the clip to move between the open and closed configuration. While the linkage assemblies  1120 ,  1220  shown in  FIGS. 11A-11B and 12A-12B  have four struts connected by two central pivot joints and two end pivot joints, it should be appreciated that in other variations, the linkage assembly may comprise fewer or more struts and/or pivot joints. Furthermore the struts may be straight (as shown in  FIGS. 12A-12B ), bent, or a combination thereof (as shown in  FIGS. 11A-11B , where struts  1122  and  1124  are bent and struts  1126  and  1128  are straight). It should also be appreciated that while the linkage assemblies  1120 ,  1220  are described herein as comprising struts and pivot joints, in other variations the linkage assembly may comprise other elements, such as struts comprising living hinges. In some variations, living hinges may limit the clip&#39;s lifetime, thereby encouraging replacement after a certain period or amount of use. 
     The clip  1100  may comprise a first arm  1102  and a second arm  1104  attached via struts  1122  and  1124 . As shown in  FIGS. 11A-11B , the struts  1122  and  1124  may have distal ends fixedly attached to the proximal ends of first and second arms  1102  and  1104 , respectively. Struts  1122  and  1124  may be connected at a pivot joint  1130  and may have a bent shape, such that if the portions of the struts  1122  and  1124  proximal to the pivot joint  1130  are rotated toward each other, the portions of the struts  1122  and  1124  distal to the pivot joint  1130  may rotate away from each other, which in turn may move first and second arms  1102  and  1104  away from each other into an open configuration, as shown in  FIG. 11B . Conversely, if the portions of the struts  1122  and  1124  proximal to the pivot joint  1130  are rotated away from each other, the portions of the struts  1122  and  1124  distal to the pivot joint  1130  may be rotated toward each other, which in turn may move first and second arms  1102  and  1104  toward each other into a closed configuration, as shown in  FIG. 11A . The proximal ends of the struts  1122  and  1124  may be rotatably attached to struts  1126  and  1128 , respectively, via pivot joints  1134  and  1136 . The proximal ends of struts  1126  and  1128 , in turn, may be rotatably connected via another pivot joint  1132 . 
     Similarly, the clip  1200  may comprise a first arm  1202  and a second arm  1204  attached via struts  1222  and  1224 . As shown in  FIGS. 12A-12B , the struts  1222  and  1224  may have distal ends fixedly attached to the proximal ends of the first and second arms  1022  and  1024 , respectively. Struts  1222  and  1224  may have a straight shape and may be connected at a middle pivot joint  1230 , such that if the portions of the struts  1222  and  1224  proximal to the pivot joint  1230  are rotated away from each other, the portions of the struts  1222  and  1224  distal to the pivot joint  1230  may also rotate away from each other, which in turn may move the first and second arms  1202  and  1204  away from each other into an open configuration, as shown in  FIG. 12B . Conversely, if the portions of the struts  1222  and  1224  proximal to the pivot joint  1230  are rotated toward each other, the portions of the struts  1222  and  1224  distal to the pivot joint  1230  may also be rotated toward each other, which in turn may move the first and second arms  1202  and  1204  toward each other into a closed configuration, as shown in  FIG. 12A . The proximal ends of the struts  1222  and  1224  may be rotatably attached to struts  1226  and  1228 , respectively, via pivot joints  1234  and  1236 . The proximal ends of struts  1226  and  1228 , in turn, may be rotatably connected via another pivot joint  1232 . 
     As mentioned above, it should be appreciated that the clips  1100 ,  1200  may comprise other configurations than those described above. For example, the linkage assembly may have more or fewer struts and/or pivot joints, other types of joints, other strut shapes, or the like. Similarly, the clip may have other designs, such as the other grasper designs described herein. In some variations, for example, the first arm and second arm may be directly rotatably connected, such as via a pivot joint at their proximal ends, or via a pivot joint located at points on the first and second arms between their ends, so that if distal portions of the first and second arms rotate away from each other, proximal portions of the first and second arms rotate toward each other. 
     In some variations, clips  1100 ,  1200  may comprise protective sheaths  1138 ,  1238  located over at least a portion of the linkage assemblies  1120 ,  1220  and/or at least a portion of the coupling elements  1112 ,  1222 , described in more detail herein. In these variations, the protective sheaths  1138 ,  1238  may comprise windows through which portions of the linkage assemblies  1120 ,  1220  may extend when the linkage assemblies  1120 ,  1220  are in an expanded configuration. 
     The clips  1100 ,  1200  may be actuated between closed and open configurations to releasably connect the clip to tissue or release the clip from tissue, respectively. In the open configuration, the first and second arms  1102  and  1104  of clip  1100 , or first and second arms  1202  and  1204  of clip  1200 , may be positioned away from each other to define a space between the arms, as shown in  FIGS. 11B and 12B . Conversely, when the clips  1100 ,  1200  are in a closed configuration, the distal portion of the arms  1102  and  1104  of clip  1100 , or distal portion of the arms  1202  and  1204  of clip  1200 , may be near each other to reduce or eliminate space between the distal portions of the arms. While the distal portions of the arms are shown in  FIGS. 11A and 12A  as contacting each other, it should be appreciated that when clip is connected to tissue, tissue positioned between the first and second arms may prevent the distal portions of the arms from contacting each other when the clip is in the closed configuration. 
     In some variations, the clips  1100 ,  1200  may be biased toward a closed configuration by one or more biasing elements, which may act on the struts and/or pivot joints to rotationally bias the first and second arms toward each other. In other variations, the clip may be biased toward an open configuration by one or more biasing elements, which may act on the struts and/or pivot joints to rotationally bias the first and second arms away from each other. In some variations, the biasing elements may comprise springs, such as torsional, extension, and/or compression springs. For example, the clip  1100  may comprise a torsional spring at pivot joint  1130  that spring-biases the clip  1100  toward a closed configuration. As another example, the clip  1100  may comprise one or more compression springs proximal to pivot joint  1130  and/or one or more extension springs distal to pivot joint  1130  configured to collapse the linkage assembly, which may spring-bias the clip  1100  toward a closed configuration. When the clip  1100  is biased toward a closed configuration, this bias may act to hold tissue positioned between the distal portions of the arms  1102  and  1104 . 
     In some variations, the one or more springs or other biasing elements, and/or the relative lengths of the struts, may be tailored to the desired force required to move the clip between open and closed configurations and/or the desired force applied by the clip in a closed configuration. For example, the relative lengths of the struts and location of pivot joints may be chosen to provide mechanical advantage to an actuation motion, for example to increase the distance between the arms of the clip for a given actuation force, or to increase the holding force between the arms. Additionally or alternatively, the relative lengths of the struts and/or springs or biasing elements may be tailored such that the amount of forced required to move the clip between open and closed configurations may depend on the strut or struts to which the force is applied. 
     The distal portions of the first and second arms  1102  and  1104  of clip  1100 , or the first and second arms  1202  and  1204  of clip  1200 , may comprise one or more features that may promote engagement with tissue, but need not. In some variations, the inner surfaces  1106 ,  1206  and  1108 ,  1208  may be roughened or texturized, which may help to reduce slipping between the arms and tissue. Additionally or alternatively, the inner surfaces  1106 ,  1206  and  1108 ,  1208  may comprise teeth or ridges, or other projections that may facilitate engagement of the first and second arms  1102 ,  1202  and  1104 ,  1204  with tissue. In some variations, the clips  1100 ,  1200  may comprise one or more coatings that may help to smooth discontinuities in the contours of the clip and may act to provide one or more atraumatic surfaces of the clip. The one or more coatings may comprise silicone, urethane, one or more nylon blends, polyethylenes, fluoropolymers, combinations thereof, and the like. 
     Generally, at least a portion of the clips  1100 ,  1200  described here may be formed from one or more materials which may be attracted to a magnetic field, as described in more detail herein, but need not be. The materials may include one or more magnetic or ferromagnetic materials, such as, for example, stainless steel, iron, cobalt, nickel, neodymium iron boron, samarium cobalt, alnico, ceramic ferrite, alloys thereof and/or combinations thereof. In variations in which the materials include steel alloys, the steel alloys may be in a martensitic state. In some variations, coldworking may be used to improve the magnetic permeability of the clips  1100 ,  1200 , for instance during the machining process. Having at least a portion of the clips  1100 ,  1200  formed from one or more metallic or magnetic materials that may be attracted to a magnetic field may allow the clips  1100 ,  1200  to be manipulated by a magnetic control assembly, as will be discussed in more detail herein. In some variations, the proximal ends of the clips  1100 ,  1200  may comprise magnetic or ferromagnetic materials to facilitate engagement by the delivery device (as described in more detail herein), but need not be. In some variations, the at least a portion of the clips  1100 ,  1200  formed from one or more materials that may be attracted to a magnetic field may be part of the coupling elements  1112 ,  1212  described herein; in other variations, this magnetic portion may be distinct from the coupling elements  1112 ,  1212 . 
     As mentioned above, the clips  1100 ,  1200  may further comprise coupling elements  1112 ,  1212 , respectively. The coupling elements  1112 ,  1212  may facilitate engagement of the clips  1100 ,  1200  to a delivery device (such as the delivery devices  1150 ,  1250 ), and may further facilitate actuation of the clips between open and closed configurations, as described herein. The coupling elements  1112 ,  1212  may be configured to facilitate temporary coupling between the clips  1100 ,  1200  and a delivery device. Generally, the linkage assemblies  1120 ,  1220  may be rotatably attached to the distal end of the coupling elements  1112 ,  1212 , as shown in  FIGS. 11A-11B and 12A-12B  (as shown there, via pivot joints  1132 ,  1232 ). At least a portion of the coupling element may comprise one or more materials that may be attracted to a magnetic field, which may facilitate temporary connection of the clip to a delivery device. The materials may include one or more magnetic or ferromagnetic materials, such as, for example, stainless steel, iron, cobalt, nickel, neodymium iron boron, samarium cobalt, alnico, ceramic ferrite, alloys thereof, and/or combinations thereof. 
     Turning to the variation of delivery device  1150  shown in  FIGS. 11A-11B  and delivery device  1250  shown in  FIGS. 12A-12B , the delivery device  1150  may comprise an actuation rod  1158 , which may releasably engage the coupling element  1112 . Delivery device  1250  may similarly comprise an actuation rod  1258 , which may releasably engage the coupling element  1212 . In some variations, the actuation rods  1158 ,  1258  may comprise one or more magnetic and/or ferromagnetic materials in at least its distal end, and thus the actuation rods may releasably engage the bodies of the coupling elements via magnetic attractive force when the actuation rods and the bodies are in proximity to each other. 
     As described above, the clip  1100  may be actuated between closed and open configurations by expanding or collapsing the linkage assembly  1120 . In some variations, the delivery device  1150  may be used to expand or collapse the linkage assembly  1120 . As shown in  FIGS. 11A-I  B, the delivery device  1150  may further comprise an outer sheath  1152  having a lumen  1154 . The outer sheath  1152  may comprise a distal lip  1156 , which may have a tapered or funnel shape, such that the diameter of the lumen  154  at the distal end of the delivery device  1150  decreases from the distal to proximal ends of the lip  1156 . At least a portion of the linkage assembly  1120  of the clip  1100  may have an overall diameter when expanded that is less than that of the lumen  1154  of the outer sheath  1152 . The clip  1100  may be actuated between closed and open configurations by moving the linkage assembly  1120  into and out of the lumen  1154 . 
     For example, in the variation shown in  FIGS. 11A-11B , as the clip  1100  is moved into the lumen  1154 , the outer surfaces of a portion of the linkage assembly  1120  (e.g., struts  1126  and  1128 ) may contact the inner surface of the outer sheath  1152 . Further movement of the linkage assembly  1120  may cause it to be compressed (i.e., may cause the struts to be rotatably moved toward each other), due to the constrained diameter of the lumen  1154 . As the linkage assembly  1120  is compressed, in the variation shown in  FIGS. 11A-11B , the arms  1102  and  1104  may be rotated away from each other, which may move the clip  1100  into an open configuration, as shown in  FIG. 1B . Conversely, movement of the clip  1100  out of the lumen  1154  may free the linkage assembly  1120 . In variations in which the clip  1100  is biased toward a closed configuration, the bias may then help to return the clip  1100  to a closed position, as shown in  FIG. 11A . 
     The clip  1100  may be moved into and out of the lumen  1154  using any suitable mechanism. In the variation of the delivery device  1150  shown in  FIGS. 11A-11B , the clip  1100  may be moved into and out of the lumen by the actuation rod  1158  located slidably within the lumen  1154 . When the actuation rod  1158  and the coupling element  1112  are engaged, retracting and advancement of the actuation rode  1158  within the lumen  1154  may move the linkage assembly  1120  into and out of the lumen, which in turn may move the clip  1100  between open and closed configurations. It should be appreciated that in order for the actuation rod  1158  to remain coupled to the clip  1100  during actuation, the engagement force between the coupling element  1112  and the actuation rod  1158  may need to be greater than the longitudinal component of the force required to actuate the clip  1100 . In some variations, this force balance may be achieved through selection of biasing elements (e.g., springs), strut lengths in the linkage assembly  1120 , and attractive force between the coupling element  1112  and the actuation rod  1158 . Once the clip  1100  holds tissue between the first and second arms  1102  and  1104 , the clip  1100  may be controlled by the magnetic control assembly to manipulate the attached tissue. The delivery device  1150  may be disengaged from the clip  1100  and removed from the anatomical cavity. If desirable, the delivery device  1150  may subsequently reengage the clip  1150  to disconnect the clip  1150  from the tissue and/or reposition the clip  1150 . 
     Additionally or alternatively, the clip  1100  may be moved between open and closed configurations by a tool separate from the delivery device  1150 . For example, a grasping tool (not shown) may be used to apply force to the linkage assembly  1120  (e.g., on two or more opposing struts, or one two or more opposing pivot joints) to move them toward a collapsed configuration. In variations in which the clip  1100  comprises a protective sheath  1138  located over at least a portion of the linkage assembly  1120  and/or at least a portion of the coupling element  1112 , force may be applied to the portions of the linkage assembly  1120  extending through windows in the protective sheath  1138 . 
     In the variation shown in  FIGS. 12A-12B , the clip  1200  may similarly be actuated between closed and open configurations by expanding or collapsing the linkage assembly  1220 . In some variations, the delivery device  1250  may be used to expand or collapse the linkage assembly  1220 . As shown in  FIGS. 12A-12B , the protective sheath  1238  of the clip  1200  may comprise a lumen  1260  configured to allow the coupling element  1212  and actuation rod  1258  to move proximally and distally relative to the arms  1202  and  1204 . When the actuation rod  1258  is moved distally relative to the arms  1202  and  1204 , the linkage assembly  1220  may be expanded (i.e., the struts may be rotatably moved away from each other), which may in turn move the clip  1200  into an open configuration, as shown in  FIG. 12B . Conversely, when the actuation rod  1258  is moved proximally relative to the arms  1202  and  1204 , the linkage assembly  1220  may be compressed (i.e., the struts may be rotatably moved toward each other), which may in turn move the clip  1200  into a closed configuration, as shown in  FIG. 12A . It should be appreciated that in order for the actuation rod  1258  to remain coupled to the clip  1200  (as shown in  FIG. 12B ) during actuation, the engagement force between the coupling element  1212  and the actuation rod  1258  may need to be greater than the longitudinal component of the force required to actuate the clip  1200 . In some variations, this force balance may be achieved through selection of biasing elements (e.g., springs), strut lengths in the linkage assembly  1220 , and attractive force between coupling element  1212  and actuation rod  1258 . Once the clip  1200  holds tissue between the first and second parts  1202  and  1204 , the clip  1200  may be controlled by the magnetic control assembly to manipulate the attached tissue. The delivery device  1250  may be disengaged from the clip  1200  (as shown in  FIG. 12A ) and removed from the anatomical cavity. If desirable, the delivery device  1250  may subsequently reengage the clip  1250  to disconnect the clip  1250  from the tissue and/or reposition the clip  1250 . 
       FIG. 5A  depicts another variation of a system in which the grasper comprises a clip. Specifically,  FIG. 5A  shows a side view of a system comprising a clip  500  and an illustrative variation of a delivery device  550  that may be used to actuate the clip  500 .  FIGS. 5B and 5C  show side views of the clip  500 , while  FIGS. 5D and 5E  show cross-sectional side views of the clip  500 . The clip  500  may be releasably coupled and decoupled from the delivery device  550 . When the clip  500  is coupled to the delivery device  550 , the delivery device  550  may actuate the clip  500  to connect the clip  500  to tissue or to detach the clip  500  therefrom. 
     As in the other variations discussed herein, in some variations depicted in  FIGS. 5A -SE, the delivery device  550  and the clip  500  may be configured for laparoscopic introduction into the body. In these variations, the clip  500  may be sized such that it may be advanced through a laparoscopic port. In some of instances, the clip  500  may be sized such that it may fit through a laparoscopic port when the clip  500  is the open configuration and in the closed configuration. In some of these variations, the largest width of the clip  500  may be less than or equal to about 10 mm, so that the clip  500  may be advanced through a 10 mm laparoscopic port. Similarly, a distal portion of the delivery device  550  may also be sized such that it may fit through a laparoscopic port. In some variations, the delivery device  550  may be configured such that the distal portion of the delivery device  550  (e.g., collet  554 , as discussed in more detail herein) may have a diameter less than or equal to about 10 mm. The clip  500  and delivery device  550  may be formed from any suitable materials, such as one or more of medical grade, high-strength plastics or metals, such as stainless steel, cobalt chromium, PEEK, one or more nylons, polyimide, or the like, and/or may at least partially be formed from magnetic materials, as described herein. 
     The clip illustrated in  FIGS. 5A-5E  may be configured to releasably pinch or grip tissue. As shown in  FIGS. 5A -SE, the clip  500  may comprise a first jaw  502  and a second jaw  504 , rotatably attached to each other by a pivot joint  506 . The first and second jaws  502  and  504  may be rotated relative to each other to actuate the clip  500  between closed and open configurations to releasably connect the clip  500  to tissue or release the clip  500  from tissue, respectively. In the open configuration, the distal portions  508  and  510  of the first and second jaws  502  and  504 , respectively, may be rotationally positioned away from each other to define a space between the distal portions  508  and  510  of the first and second jaws  508  and  510 , as shown in  FIGS. 5C and 5E . Similarly, while the clip  500  is in a closed configuration, the distal portions  508  and  510  of the first and second jaws  502  and  504  may be rotationally biased toward each other to reduce or eliminate space between the distal portions  508  and  510  of the first and second jaws  502  and  504 . While the distal portions  508  and  510  of the first and second jaws  502  and  504  are shown in  FIGS. 5A, 5B, and 5D  as contacting each other, it should be appreciated that when clip  500 , tissue positioned between the jaws  502  and  504  may prevent the distal portion  508  of the first jaw  502  from contacting the distal portion  510  of the second jaw  504  when the clip  500  is placed in the closed configuration. 
     In some variations, the distal ends  508  and  510  of the first jaw  502  and the second jaw  504 , respectively, may be rotationally biased toward each other. For example, in some variations the clip  500  may comprise a spring, such as a torsional spring, that may spring-bias the distal ends  508  and  510  of the first and second jaws  502  and  504  toward each other, biasing the clip  500  into a closed position. In other variations, the clip  500  may comprise a spring, such as a compression spring, that may spring-bias the proximal ends  512  and  514  of the first and second jaws  502  and  504 , respectively, away from each other, biasing the clip  500  into a closed position. The bias toward the closed configuration may act to hold tissue positioned between the distal portions  508  and  510  of the first and second jaws  502  and  504 . 
     In some variations, the jaws  502  and  504  of the clip  500  may be shaped such that when the clip  500  is in the closed configuration, the proximal portions  512  and  514  of the first jaw  502  and second jaw  504 , respectively, define a substantially cylindrical shape, having a substantially constant diameter. This may reduce the overall profile of the clip  500 . The distal portions  508  and  510  may also form a tapered cylindrical or conical shape in the closed configuration. The substantially cylindrical shape of the proximal end of clip  500 , with rounded, convex surface contours, may also help to make the clip  500  less traumatic to surrounding anatomy. 
     Additionally, the substantially cylindrical shape of the proximal end of clip  500  may also facilitate actuation of the clip  500  by both the delivery devices described here and standard laparoscopic tools, as described in detail herein. The jaws  502  and  504  of the clip  500  may also have a ramped shape, such that in the closed configuration, the distal portions  512  and  514  of the clip  500  define cylindrical shape, while in the open configuration, the distal portions  512  and  514  of the clip  500  define a tapered cylindrical shape due to the ramp angle of the proximal portions (labeled as  530 ), such that the bottom surface of the first jaw  502  does not extend past the bottom surface of the second jaw  504 , and the top surface of the second jaw  504  does not extend past the top surface of the first jaw  502 , when in an open configuration, as shown in  FIGS. 5C and 5E . Moreover, the inner portions of jaws  502  and  504  may have ramped surfaces  526  and  528 , which are rotationally separated in a closed configuration, which may allow rotation between the jaws  502  and  504 . This ramped shaped allows the jaws to rotate about pivot joint  506  into an open configuration, even though the proximal portions of the jaws may define a substantially cylindrical shape in a closed configuration. The ramps may be made of varying angles: larger angles of ramping at edge  526 ,  528 , and  530  allow for greater freedom of rotation of the jaws, and thus greater separation between the first jaw  502  and second jaw  504  in the open configuration, while smaller angles of ramping allow for less freedom of rotation of the jaws, and thus less separation between the first jaw  502  and the second jaw  504 . 
     The distal ends  508  and  510  of the first and second jaws  502  and  504 , respectively, may comprise one or more features that may promote engagement with tissue, but need not. In some variations, the inner surfaces  516  and/or  518  of the distal ends  508  and  510 , respectively, may be roughened or texturized, which may help to reduce slipping between the jaws and tissue. Additionally or alternatively, the inner surfaces  516  and/or  518  may comprise teeth or ridges  520  (such as shown in  FIGS. 5C and 5E ) or other projections that may facilitate engagement of the first and second jaws  502  and  504  with tissue. In some variations of the clip described here, the clip may comprise one or more coatings that may help to smooth discontinuities in the contours of the clip and may act to provide one or more atraumatic surfaces of the clip. The one or more coatings may comprise silicone, urethane, one or more nylon blends, polyethylenes, fluoropolymers, combinations thereof, and the like. Additionally or alternatively, the proximal portion of the clip  500  may comprise a coating to increase the ability of a delivery device to engage and actuate the clip  500 . 
     Generally, at least a portion of the clip  500  described here may be formed from one or more materials which may be attracted to a magnetic field, as described in more detail herein, but need not be. The materials may include one or more magnetic or ferromagnetic materials, such as, for example, stainless steel, iron, cobalt, nickel, neodymium iron boron, samarium cobalt, alnico, ceramic ferrite, alloys thereof and/or combinations thereof. In variations in which the materials include steel alloys, the steel alloys may be in a martensitic state. In some variations, coldworking may be used to improve the magnetic permeability of the clip  500 , for instance during the machining process. Having at least a portion of the clip  500  formed from one or more metallic or magnetic materials that may be attracted to a magnetic field may allow the clip  500  to be manipulated by a magnetic control assembly, as will be discussed in more detail herein. In some variations, the proximal ends and/or protrusions of the clip  500  may comprise magnetic or ferromagnetic materials to facilitate engagement by the delivery device (as described in more detail herein), but need not. 
     As mentioned above, the delivery device  550  may be releasably coupled and actuate the clip  500  shown in  FIGS. 5A-5E . As shown in  FIG. 5A , the delivery device  550  may comprise and outer sheath  552  and a collet  554 . The collet  554  may be at least partially housed within a lumen of the outer sheath  552 , and may be connected to an actuation rod  566 . The actuation rod  566  in turn may be slidably disposed within the outer sheath  552  such that advancement and retraction of the actuation rod  566  relative to the outer sheath  552  also advances and retracts, respectively, the collet  554  relative to the outer sheath  552 . The collet  554  may have an increased thickness at its distal end  558 , and may be configured to fit within the lumen at the distal end  560  of outer sheath  552 . Specifically, the actuation rod  566  may move the collet  554  between an advanced position (as shown in  FIG. 5A ) in which the collet  554  extends from a distal end of the outer sheath  552  and a retracted position in which the collet  554  is withdrawn into the outer sheath. In some variations, the thickness of the collet  554  may increase from a proximal portion of the collet  554  to a distal portion of the collet  554 . When the collet  554  is in the advanced position, the collet  554  may radially expand or otherwise be radially expanded such that a lumen of the collet  554  has a first diameter. In some variations, the first diameter may be large enough to accommodate the clip  500  when the clip is in the closed configuration. As the collet  554  is retracted into the outer sheath  552 , the outer sheath  552  may constrain the outer diameter of the collet (e.g., providing a radially-inward force to collet  554  to allow the collet to fit inside the outer sheath  552 ). As the outer diameter of the collet  554  is limited by the outer sheath  552 , the increasing thickness of the collet  554  may reduce the diameter of the lumen of the collet  554 . For example, the lumen of the collet may be reduced to a second diameter that is smaller than the first diameter. In some instances, this second diameter may be sufficiently small to actuate the clip  500  from a closed to an open configuration, as discussed in more detail herein. In some variations, the distal end  560  of the outer sheath  552  may have two slots  562  on opposing sides on the distal end  560  of outer sheath  552 . In these variations, as the collet  554  is moved to the retracted position, the outer sheath  552  may constrain the collet  554  in a first direction (as indicated by arrows  564 ), but not in a second direction (e.g., in a direction perpendicular to the page). This may allow the collet  554  to apply a force to the clip  500  in a first direction without needing to apply a force to the clip  500  in a second direction. 
     As mentioned above, the collet  554  may be configured to receive a proximal portion of the clip  500  when the collet  554  is in an advanced position, as shown in  FIG. 5A . In some variations, the first diameter mentioned above may be slightly smaller than an outer diameter of the proximal portion of the clip  500 , such that the collet  554  is slightly expanded by the clip  500 . In these variations, the collet  554  may apply inward normal force to the clip that is sufficient to temporarily hold the clip  500 , but that does not move the jaws  502  and  504  into an open configuration. When the collet  554  is moved to a retracted position (e.g., when the outer sheath  552  is advanced relative to the collet  554 ), the reduction of diameter of the lumen of the collet  554  may apply inward force on the proximal ends  512  and  514  of jaws  502  and  504 , respectively. This may cause the proximal ends  512  and  514  to move toward each other, and in turn cause the distal portions  508  and  510  to move away from each other and into an open configuration, as shown in  FIGS. 5C and 5E . In variations where the outer sheath  552  includes slots  562 , the clip  500  may be aligned with the slots  562  of the outer sheath  552  such that the plane of rotation of the jaws is parallel to the first direction  552 , which may allow the force provided in the first direction  552  by the collet  554  to actuate the clip  500 . 
     Conversely, when the outer sheath  552  is retracted proximally relative to the collet  554 , the clip may return to a closed configuration (e.g., by virtue of a spring bias toward the closed configuration), as the constraining force provided by the outer sheath may be removed as the shaft is retracted. When tissue is positioned between the distal portions of the jaws, moving the clip  500  to the closed configuration may cause the clip  500  to releasably connect to the tissue. Once the clip  500  holds tissue between the first jaw  502  and the second jaw  504 , the location of the clip  500  may be controlled by a magnetic control assembly to manipulate the attached tissue. The delivery device  550  may then be disengaged from the clip  500  and removed from the anatomical cavity. If desirable, the delivery device  550  may subsequently reengage the clip  500  to disconnect the clip  500  from the tissue and/or to reposition the clip  500 . 
       FIGS. 6A and 6B  depict side and perspective views, respectively, of another variation of a system in which the grasper comprises a clamp. As shown there, the system may comprise a clamp  600  and a delivery device  650 . The clamp  600  may be releasably coupled to and decoupled from the delivery device  650 , as shown in  FIGS. 6A and 6B , respectively. When the clamp  600  is coupled to the delivery device  650 , the delivery device  650  may actuate the clamp  600  to connect the clamp  600  to tissue or to detach the clamp  600  therefrom. 
     As in the variations discussed above, in some variations, the delivery device  650  and the clip  600  may be configured for laparoscopic introduction into the body. In these variations, the clamp  600  may be sized such that it may be advanced through a laparoscopic port. In some instances, the clamp  600  may be sized such that it may fit through a laparoscopic port when the clamp  600  is in the open configuration, the closed configuration, or either the open or closed configuration. In some of these variations, the largest width of the clamp  600  in a closed configuration may be less than or equal to about 10 umm, so that the clamp  600  may be advanced through a 10 mm laparoscopic port when the clip is in the closed configuration. Similarly, a distal portion of the delivery device  650  may also be sized such that it may fit through a laparoscopic port. In some variations, the delivery device  650  may be configured such that the distal portion of the delivery device  650  (e.g., an outer sheath  652 , as discussed in more detail herein) may have a diameter less than or equal to about 10 mm. The clamp  600  and delivery device  650  may be formed from any suitable materials, such as one or more of medical grade, high-strength plastics or metals, such as stainless steel, cobalt chromium, nickel titanium, PEEK, one or more nylons, polyimide, or the like, and/or may at least partially be formed from magnetic materials, as described herein. 
     The clamp  600  may comprise a first gripping pad  602 , a second gripping pad  604 , and a wire  606  connecting the first pad  602  and the second pad  604 . The wire  606  may have a scissor-like configuration, manipulation of which may allow the clamp  600  to be actuated between closed and open configurations. This in turn may allow the clamp  600  to releasably connect to tissue. When the clamp  600  is in an open configuration, the first pad  602  and the second pad  604  may be separated to define a space between the first pad  602  and the second pad  604 , such as shown in  FIG. 6A . When the clamp  600  is moved to the closed configuration, the distance between the pads  602  and  604  may be reduced. In some instances, the pads may be positioned in contact with each other when the clamp is in its closed configuration. When tissue is positioned between the pads  602  and  604  (such as tissue  690  shown in  FIG. 6B ), the tissue may prevent the first pad  602  from contacting the second pad  604  when the clamp  600  is in a closed configuration. 
     In the variation shown in  FIGS. 6A and 6B , the wire  606  may comprise first and second distal portions (labeled  608  and  610 , respectively) and first and second proximal portions (labeled  612  and  614 , respectively), and may have a diamond-like shape. A distal end or portion of the first distal portion  608  may be connected to the first jaw  602 , and a proximal end or portion of the first distal portion  608  may be connected to the first proximal portion  612 . Similarly, a distal end or portion of the second distal portion  610  may be connected to the second jaw  604 , and a proximal end or portion of the second distal portion  610  may be connected to the first proximal portion  614 . The first and second proximal portions  612  and  614  may connected at their proximal ends, and the two distal portions  608  and  610  may cross each other to cause the wire  606  to define a substantially diamond shape. 
     In some variations, the wire  606  may be formed with loops at the junctions between the first distal portion  608  and first proximal portion  612 , between second distal portion  610  and second proximal portion  614 , and between first and second proximal portions  612  and  614  (these loops are labeled as  620 ,  622 , and  616 , respectively). Each loop may comprise one or more coils. Each loop may act as a torsion spring, such that rotation between two portions from a resting position may store energy in the loop connecting them, thereby providing a biasing force toward the resting position. Accordingly, the loops  620 ,  622 , and  616  may bias the wire  606  toward a closed configuration (such as shown in  FIG. 6B ), and may press the first  602  and second  604  pads together in the closed configuration. While shown in  FIGS. 6A and 6B  as being formed from one continuous wire, the wire  606  need not be. In other variations, the wire  606  may be comprised of two or more segments of wire that may be joined together. Additionally or alternatively, although the first and second distal portions  608  and  610  and the first and second proximal portions  612  and  614  of the wire  606  are shown in  FIGS. 6A and 6B  as being substantially straight segments, all or some of these wire segments may be comprise one or more curves. Additionally or alternatively, while shown in  FIGS. 6A and 6B  as having loops at each of the junctions between the first proximal portion  608  and the first distal portion  612 , the second proximal portion  610  and the second distal portion  614 , and between the first and second distal portions  612  and  614 , the wire  606  may be configured such that it has loops at only some or none of these junctions. 
     The wire may have any suitable properties to have a desired torsion coefficient, and in turn a desired clamping force on tissue. For example, the wire diameter, loop diameter, and number of coils in each loop may affect the torsion. Increasing the wire diameter, decreasing the loop diameter, and/or decreasing the number of coils per loop may increase the torsion coefficient, and in turn the clamping force on tissue. Conversely, decreasing the wire diameter, increasing the loop diameter, and/or increasing the number of coils per loop may decrease the torsion coefficient, and in turn the clamping force on tissue. In some variations, the wire diameter may be between about 0.015 inches and about 0.030 inches. In other variations, the wire diameter may be between about 0.01 inches and about 0.02 inches, about 0.02 inches and about 0.04 inches, about 0.04 inches and about 0.05 inches, about 0.05 inches and about 0.06 inches, or greater. It should be appreciated that in some variations the wire may have a constant diameter along its length, while in other variations the wire may have a variable diameter along its length. In some variations, the loop diameters may be between about 1 mm to about 5 mm (e.g., between about 1 mm and about 2 mm, about 2 mm and about 3 mm, about 3 mm and about 4 mm, about 4 mm and about 5 mm). In other variations, the loop diameters may be between about 5 mm and about 6 mm, about 6 mm and about 7 mm, about 7 mm and about 8 mm, about 8 mm and about 9 mm, about 9 mm and about 10 mm, or greater. The loop diameters may be sized such that they are configured to fit within delivery device  650 . It should be appreciated that each loop may have a different diameter than the other loops, or two or more loops (including all loops) may have the same diameter. In some variations, the loops may comprise a single coil. In other variations, the loops may comprise multiple coils (e.g., two, three, four, five, six, or more). The number of coils may be such that the loops may be configured to fit within delivery device  650 . It should be appreciated that each loop may have a different number of coils, or two or more loops (including all loops) may have the same number of coils. 
     All or part of the inner surfaces  610  and  612  of the pads  602  and  604 , respectively, may comprise one or more features that may promote engagement with tissue, but need not. In some variations, all or part of the inner surfaces  610  and  612  of the pads  602  and  604 , respectively, may be roughened or texturized, which may help to reduced slipping between the pads and tissue. Additionally or alternatively, the all or part of the inner surfaces  610  and  612  may comprise teeth or ridges  618  (as shown in  FIG. 6A ) or other projections that may facilitate engagement of the pads  602  and  604  with tissue. In some variations of the clamp described here, the clamp may comprise one or more coatings that may help to smooth discontinuities in the contours of the grasper and may act to provide one or more atraumatic surfaces of the grasper. 
     The one or more coatings may comprise silicone, urethane, one or more nylon blends, polyethylenes, fluoropolymers, combinations thereof, and the like. 
     Generally, at least a portion of the clamp  600  described here may be formed from one or more materials which may be attracted to a magnetic field, as described in more detail herein, but need not be. The materials may include one or more magnetic or ferromagnetic materials, such as, for example, stainless steel, iron, cobalt, nickel, neodymium iron boron, samarium cobalt, alnico, ceramic ferrite, alloys thereof and/or combinations thereof. In variations in which the materials include steel alloys, the steel alloys may be in a martensitic state. In some variations, coldworking may be used to improve the magnetic permeability of the clamp  600 , for instance during the machining process. Having at least a portion of the clamp  600  formed from one or more metallic of magnetic materials that may be attracted to a magnetic field may allow the clamp  600  to be manipulated by a magnetic control assembly, as will be discussed in more detail herein. 
     The clamp  600  may be manipulated, actuated, and or delivered by a delivery device. For example,  FIGS. 6A and 6B  depict a variation of a delivery device  650  which may be used to actuate the clamp  600 . As shown there, the delivery device  650  may comprise a an outer sheath  652  having a lumen  654  and a pull wire  656  having a distal hook  658  extending through the outer sheath  652 . While the outer sheath  652  is shown as having a constant diameter in  FIGS. 6A and 6B , in other variations the outer sheath may have a tapered shape, such that the diameter of the outer sheath increases or decreases from the distal to proximal ends. 
     To releasably couple the clamp  600  to the delivery device  650 , the distal hook  658  may engage a portion of the wire  606 , and the distal hook  658  may be withdrawn relative to the outer sheath  652  (e.g., by withdrawing the pull wire  656 ) to pull the clamp  600  into contact with the outer sheath  652 . Holding the clamp  600  in contact with the outer sheath  652  using the distal hook  658  may temporarily keep the clamp  600  engaged with the delivery device  650 . In some instances, to engage the wire  606 , the distal hook  658  may be placed into the loop  616  between the first and second proximal portions  612  and  614  of the wire  606 . The position of the pull wire  656  and the distal hook  658  relative to the outer sheath  652  may be controlled by any suitable mechanism, such as a triggering mechanism that may be manipulated by the user at a proximal portion of the delivery device (e.g., a handle or the like). 
     The distal hook  658  and pull wire  656  may also be manipulated to actuate the clamp  600 . When the distal hook  658  is retracted relative to the outer sheath  652  to pull the clamp  600  into contact with the outer sheath  652 , further retraction of distal hook  658  may cause a distal end  660  of the cylinder  652  to contact and press against the first and second proximal portions  612  and  614  of the wire  606 . This may cause the first and second proximal portions  612  and  614  to rotate towards each other, which in turn may push the pads  602  and  604  away from each other to move the clamp  600  into an open configuration, as shown in  FIG. 6A . 
     Conversely, the distal hook  658  may be advanced (or the outer sheath  652  may be moved proximally) to advance the clamp  600  relative to the outer sheath  652 . As the clamp  600  is advanced relative to the outer sheath  652 , the constraining forces provided by the outer sheath may be removed, and the first and second proximal portions  612  and  614  may rotate away from each other (e.g., via mechanical energy stored in the loop  616 ), which may move the first and second pads  602  and  604  toward each other, thereby returning the clamp  600  to a closed configuration. When a tissue (such as tissue  690  shown in  FIG. 6B ) is positioned between the first and second pads  602  and  604  when the clamp  600  is in an open configuration, moving the clamp  600  to a closed configuration may releasably connect the clamp  600  to tissue  690 . Once the clamp  600  holds tissue between the first pad  602  and the second pad  604 , the clamp  600  may be controlled by the magnetic control assembly to manipulate the attached tissue, as discussed herein. The hook  648  may then be disengaged from the clip loop  616  to disconnect the grasper  600 , which can then be removed from the anatomical cavity. If desirable, the delivery device  650  may subsequently reengage the clamp  600  to disconnect the clamp  600  from the tissue and/or reposition the clamp  600 . 
     In some variations of the systems described here, the system may comprise a grasper configured to attach to tissue using a vacuum between the grasper and the tissue.  FIGS. 7A and 7B  depict one such variation of a system comprising a grasper  700  and a delivery device  750 . It should be appreciated that the grasper  700  may be actuated and delivered using any suitable delivery device (such as those described here) and the delivery device  750  may be used to actuate and/or deliver any suitable grasper (such as those described here). When the grasper  700  is coupled to the delivery device  750 , the delivery device  750  may actuate the grasper  700  to connect the grasper  700  to tissue or to detach the grasper  700  therefrom. The grasper  700  and the delivery device  750  will each be discussed in more detail herein. 
     As in other variations discussed herein, in some variations, the delivery device  750  and the grasper  700  may be configured for laparoscopic introduction into the body, such as discussed in more detail herein. In these variations, the grasper  700  may be sized such that it may be advanced through a laparoscopic port. In some instances, the grasper  700  may be sized such that it may fit through a laparoscopic port when the grasper  700  is in the open configuration, the closed configuration, or either the open or closed configuration. In some of these variations, the largest width of the grasper  700  in a closed configuration may be less than or equal to about 10 mm, so that the grasper  700  may be advanced through a 10 mm laparoscopic port when the clip is in the closed configuration. Similarly, a distal portion of the delivery device  750  may also be sized such that it may fit through a laparoscopic port. In some variations, the delivery device  750  may be configured such that the distal portion of the delivery device  750  may have a diameter less than or equal to about 10 mm. 
     In the embodiment of the grasper  700  shown in  FIGS. 7A and 7B , the grasper  700  may be configured to releasably adhere to tissue using suction. As shown in  FIGS. 7A and 7B , the grasper  700  may comprise a suction cup  702 , a tube  704 , and a bladder  706 . Generally, the tube  704  may have a lumen extending between a distal opening  708  and a proximal opening  710  of the tube  704 , which may fluidly connect the suction cup  702  and the bladder  706 . Specifically, the distal opening  708  of the tube  704  may connect to an opening  712  through the suction cup  702 , which may allow the bladder  706  to displace air from or draw air through the suction cup  702 . Specifically, compression of the bladder  706  may push air out of the bladder  706 , which in turn may drive the air through the tube  704  and out of the suction cup  702 . 
     To connect the grasper  700  to tissue, the bladder  706  may be compressed to evacuate air from the bladder  706  out of the suction cup  702 , and the suction cup  702  may be positioned against tissue. With the suction cup  702  positioned against tissue, the compressive force applied to the bladder  706  may be at least partially released. Due to the tendency of the bladder  706  to return to an uncompressed configuration, the bladder  706  may attempt to draw air into the bladder  706 , but the presence of the tissue in the suction cup  702  may prevent air from passing into the bladder  706  through the suction cup  702 . Accordingly, the bladder  706  may instead provide a vacuum force to the tissue via the tube  704  and the opening  712  in the suction cup  702 . This vacuum force may hold the grasper  700  against the tissue. To release the grasper  700  from tissue, the bladder  706  may again be compressed to remove the vacuum force. 
     Generally, the suction cup  702  may be configured to promote connection of the grasper  700  to tissue. For example, the suction cup  702  may be formed from a shape that defines a cavity configured to at least partially receive tissue. In some variations, the suction cup  702  may have a hemispherical or a conical shape. Additionally or alternatively, the suction cup  702  may comprise one or more tabs or other protrusions that may be configuration to at least partially wrap around tissue. In these variations, the tabs/protrusions may engage tissue and may help to hold it temporarily in place. 
     While the bladder  706  is shown in  FIGS. 7A and 7B  as having a generally spherical shape, it should be appreciated that the bladder may have any suitable shape, such as, for example, a bulbous shape, a cylindrical shape, a box shape, or the like. The size of the bladder  706  and suction cup  702  may be chosen based on the desired suction strength. For example, a larger bladder and/or suction cup may allow the grasper  700  to provide a larger vacuum force to tissue, which may more strongly adhere the grasper  700  to the tissue. 
     The grasper  700  and delivery device  750  may be formed from any suitable materials, such as one or more of medical grade, high-strength plastics or metals, such as stainless steel, cobalt chromium. PEEK, one or more nylons, polyimide, or the like, and/or may be at least partially formed from materials that may be attracted to a magnetic field, as described herein. In some variations, the bladder  706  may be formed from one or more resilient materials, such as one or more rubbers (e.g., silicon, one or more thermoset elastomers) or urethanes such that the bladder  706  has a tendency to return to an uncompressed configuration. In these variations, as the bladder  706  returns to an uncompressed configuration, the bladder  706  may draw air into the bladder  706  through the suction cup  702  and the tube  704 . Additionally, in some variations, the suction cup  702  may be formed from a deformable or flexible material, which may allow the suction cup  702  to deform to accommodate irregular tissue. For example, in some variations the suction cup  702  may be formed from one or more rubbers (e.g., silicon, one or more thermoset elastomers) or urethanes. It should be appreciated that the suction cup  702  and bladder  706  may be formed from the same material or combination of materials, or may be formed from different materials. 
     Generally, at least a portion of the grasper  700  described here may be formed from one or more materials which may be attracted to a magnetic field, as described in more detail herein, but need not be. The materials may include one or more magnetic or ferromagnetic materials, such as, for example, stainless steel, iron, cobalt, nickel, neodymium iron boron, samarium cobalt, alnico, ceramic ferrite, alloys thereof and/or combinations thereof. In variations in which the materials include steel alloys, the steel alloys may be in a martensitic state. In some variations, coldworking may be used to improve the magnetic permeability of the grasper  700 , for instance during the machining process. Having at least a portion of the grasper  700  formed from one or more metallic or magnetic materials that may be attracted to a magnetic field may allow the grasper  700  to be manipulated by a magnetic control assembly, as will be discussed in more detail herein. In some variations, at least a portion of the bladder may comprise magnetic or ferromagnetic materials to facilitate engagement by the delivery device (as described in more detail herein), but need not. 
     One or more delivery devices may be configured to compress and/or release the bladder  706  to releasably connect the grasper  700  to tissue. For example,  FIGS. 7A and 7B  show one such variation of a delivery device  750 . As shown there, the delivery device  750  may comprise an elongate sheath  752  and an engagement portion  754 . The elongate sheath  752  may comprise a lumen  758  extending at least partially therethrough, which may be sized to at least partially hold the engagement portion  754 . The elongate sheath  752  and the engagement portion  754  maybe cooperate to hold and actuate a grasper (such as the grasper  700  shown in  FIGS. 7A-7B ), as will be discussed in more detail herein. 
     The engagement portion  754  may comprise a first elongate member  760  and second elongate member  762 . The engagement portion  754  may have an open and a closed configuration. In some variations, the first elongate member  760  and second elongate member  762  may be rotatably connected or otherwise attached at their proximal ends  764  and  766 , respectively, but need not be attached. In variations in which the elongate members are attached, the attachment mechanism may allow for the engagement portion  754  to be moved between the open and closed configurations. In some variations, the attachment mechanism may be a pivot joint. In other variations, the first elongate member  760  and second elongate member  762  may be welded, fused, or otherwise joined together, and the members may be sufficiently flexible to allow the engagement portion  754  to move between closed and open configurations. 
     When the engagement portion  754  is moved to the open configuration, the distal portions  768  and  770  of first elongate member  760  and second elongate member  762 , respectively, may be spaced apart to define a space between the distal portions  768  and  770  of first elongate member  760  and second elongate member  762 , as shown in  FIG. 7A . In variations in which the elongate members are attached such that an attachment mechanism rotatably connects the first and second elongate members  760  and  762 , in the open configuration, the distal portions  768  and  770  of the first and second elongate members  760  and  762  may be rotationally biased away from each other to define a space between the distal portions  768  and  770  of first and second elongate members  760  and  762 . In the closed configuration, the distal portions  768  and  770  of first elongate member  760  and second elongate member  762  may be moved closer than in the open configuration, as shown in  FIG. 7B . In variations in which the elongate members are attached such that an attachment mechanism rotatably connects the first and second elongate members  760  and  762 , in the closed configuration, the distal portions  768  and  770  of the first and second elongate members  760  and  762  may be rotationally biased toward each other to reduce or eliminate space between the distal portions  768  and  770  of the first and second elongate members  760  and  762 . 
     While it may be possible for the distal portion  768  of the first elongate member  760  to be moved into contact with the distal portion  770  of the second elongate member  762 , this may not be necessary for the engagement portion  754  to releasably engage a grasper. For example, when the engagement portion  754  releasably engages with the grasper  700  depicted in  FIGS. 7A-7B , the grasper  700  may prevent the distal portions  768  and  770  of the first elongate member  760  and second elongate member  762  from contacting each other, and/or may prevent the first elongate member  760  and second elongate member  762  from fully closing. 
     In some variations, the first elongate member  760  and the second elongate member  762  may be configured such that their distal ends  768  and  770  are biased away from each other, which may in turn bias the engagement portion  754  toward and open configuration. For example, in some variations the engagement portion  754  may comprise a spring (not shown), such as a compression spring, which may spring-bias the engagement portion  204  toward an open position, such as shown in  FIG. 7A . In variations where the first elongate member  760  and second elongate member  762  are welded together, they may be welded in an open configuration but may be sufficiently flexible to allow the first elongate member  760  and second elongate member  762  to be pressed toward each other into a closed configuration. In other variations, the first and second elongate members  760  and  762  may be spring-biased toward each other, for instance with an extension spring, leaf spring, or torsional spring, which may bias the engagement portion  754  toward a closed configuration. In some variations, the delivery device  750  may comprise a control that may be used to overcome the bias of an engagement portion (such as the engagement portion  754 ) toward a closed configuration, which may thus allow the engagement portion  754  to be moved into an open configuration. 
     As mentioned above, the engagement portion  754  of the delivery device  750  may be configured to releasably couple to and actuate a grasper, such as the grasper  700  shown in  FIGS. 7A-7B . For example, in some instances the distal portions  768  and  770  of first elongate member  760  and second elongate member  762  may be configured to releasably engage the grasper  700 . The bladder  706  of grasper  700  may be positioned between the distal ends  768  and  770  of the first and second elongate members  760  and  762 , respectively, of the delivery device  750 . The grasper  700  may be held between the distal ends  768  and  770  of the first and second elongate members by a clamping force between the distal ends  768  and  770 . For example, in variations in which the engagement portion  754  of the delivery device  750  is biased toward a closed configuration, the biasing force may create a clamping force. 
     In some variations, the distal portions  768  and  770  of the first and second elongate members  760  and  762 , respectively, may comprise features that may improve the ability of the delivery device  750  to reliably grip onto a grasper (such as grasper  700 ), but need not comprise such features. For example, the delivery device  750  may comprise apertures or recesses (e.g., apertures  772  shown in  FIGS. 7A-7B ) extending at least partially through the distal ends  768  and  770  of the first and second elongate members  760  and  762 . When the grasper  700  is positioned between the distal ends  768  and  770  of first and second elongate members  760  and  762 , the bladder  706  may be configured to sit within one or more of the apertures  772 . This may help to maintain engagement between the engagement portion  754  and the grasper  700  by allowing a greater area of contact between the bladder  706  and delivery device  750 , and by the inner walls of the apertures  772  exerting inward forces on the bladder  706  that may tend to keep the bladder  706  within the apertures  772 . In some variations, the bladder  706  may additionally be secured in the apertures  772  by a force biasing the first and second elongate members  760  and  762  toward each other, as described herein. 
     In some variations, there may be an attractive force between distal portions  768  and  770  of first and second elongate members  760  and  762  and one or more portions of the grasper  700  (e.g., the bladder  706 ). In some variations, this attractive force may be magnetic. In variations in which the attractive force is magnetic, the magnetic force may be generated by the distal portions  768  and  770  of the first and second elongate members  760  and  762 , and one or more portions of the grasper  700 , comprising magnetic or ferromagnetic materials. In variations in which one or more portions of a grasper (e.g., the bladder  706  of grasper  700 ) comprise magnetic materials, the distal portions  768  and  770  of the elongate members  760  and  762  may comprise magnetic or ferromagnetic materials; in variations in which one or more portions of a grasper (e.g., the bladder  706  of grasper  700 ) comprise ferromagnetic materials and no magnetic materials, the distal portions  768  and  770  of the elongate members  760  and  762  may comprise magnetic materials. 
     When the delivery device  750  has engaged a grasper (such as grasper  700  shown in  FIGS. 7A-7B ), the delivery device  750  may additionally be configured to actuate the grasper between uncompressed and compressed configurations. To move the grasper  700  between its uncompressed and compressed configurations, the engagement portion  754  may be selectively moved between its open and closed configurations, respectively. For example, as the engagement portion  754  is moved toward its closed configuration (such as shown in  FIG. 7B ), the distal portions  768  and  770  of the first and second elongate members  760  and  762  may be moved toward each other. This may apply a compressive force to the bladder  706  of grasper  700 , which may cause the grasper  700  to move into a compressed configuration. Conversely, moving the engagement portion  754  toward its open configuration may release the compressive force on bladder  706  of grasper  700 , which may allow the grasper  700  to return to its uncompressed configuration, such as shown in  FIG. 7A . 
     The engagement portion  754  may be moved between its open and closed configurations in any suitable manner. In some variations, the engagement portion  754  may be actuated by advancing or retracting the engagement portion  754  through the lumen  758  of elongate sheath  752  of the delivery device  750 . Movement of the elongate sheath  752  distally relative to the engagement portion  754  may cause the inner surface of elongate sheath  752  at the distal end  774  to contact the outer surface of the first and second elongate members  760  and  762 . Further movement of the elongate sheath  752  distally relative to the engagement portion  754  may then cause the elongate sheath  752  to press against the outer surfaces of the first and second elongate members  760  and  762 , which may force the distance between the first and second elongate members  760  and  762  to stay constant at the point where the first and second elongate members  760  and  762  contact the elongate sheath  752 . As a result, the movement of the elongate sheath  752  distally relative to the engagement portion  754  may push the engagement portion  754  toward a closed configuration. When the engagement portion  754  is moved toward a closed configuration, distal ends  768  and  770  of the first and second elongate members  760  and  762  may be moved toward each other, which in turn may compress the bladder  706  of grasper  700 . This may move the grasper  700  into a compressed configuration, as shown in  FIG. 7B . Conversely, when the elongate sheath  752  is moved proximally relative to the engagement portion  754 , the elongate sheath  752  may contact the engagement portion  754  at an increasingly proximal portion of the first and second elongate members  760  and  762 , which may allow the first elongate member  760  and the second elongate member  762  to move away from each other, returning to an open configuration, as shown in  FIG. 7A . This may release the pressure on the bladder  706  of grasper  700 , which in turn may cause the bladder  706  of  700  to return to an uncompressed configuration, as shown in  FIG. 7A . 
     The delivery device  750  may be used to releasably attach a grasper (such as grasper  700  depicted in  FIGS. 7A-7B ) to tissue. The grasper  700  may be engaged by the delivery device  750  (such as discussed in more detail herein), and the grasper  700  and a distal portion of the delivery device  750  may be advanced into a patient (e.g., into a body cavity such as the abdominal cavity) through an access site (e.g., such as a laparoscopic port). Once the grasper  700  is positioned within the body cavity, the delivery device  750  may be actuated to selectively move the grasper  700  between its compressed and uncompressed configurations in order to create a vacuum force to adhere the suction cup  702  of the grasper  700  to tissue. Once the grasper  700  is adhered to the tissue, the grasper  700  may be controlled by the magnetic control assembly to manipulate the attached tissue, as discussed herein. The engagement portion  754  may then be disengaged from the grasper  700  and removed from the anatomical cavity. If desirable, the delivery device  750  may subsequently reengage the grasper  700  to disconnect the grasper  700  from the tissue and/or reposition the grasper  700 . 
       FIGS. 8A and 8B  depict another variation of a system described here in which the system comprises a grasper configured to attach to tissue using a vacuum between the grasper and tissue. As shown there, the system may comprise a grasper  800  and a delivery device  850 . Specifically,  FIGS. 8A and 8B  show perspective views of the grasper  800  and the delivery device  850 . When the grasper  800  is coupled to the delivery device  850 , the delivery device  850  may actuate the grasper  800  to connect the grasper  800  to tissue or detach the grasper therefrom, as described in detail herein. The grasper  800  may be releasably coupled to the delivery device  850  and decoupled from the delivery device  850 . When the grasper  800  is coupled to the delivery device  850 , the delivery device  850  may actuate the grasper  800  to connect the grasper  800  to tissue or to detach the grasper  800  therefrom. 
     In some variations, the delivery device  850  and the grasper  800  may be configured for laparoscopic introduction into the body, such as discussed in more detail herein. In these variations, the grasper  800  may be sized such that it may be advanced through a laparoscopic port. In some of these variations, the largest width of the grasper  800  (e.g., the diameter of the suction cup  802 ) may be less than or equal to about 10 mm, so that the grasper  800  may be advanced through a 10 mm laparoscopic port. Similarly, a distal portion of the delivery device  850  may also be sized such that it may fit through a laparoscopic port. In some variations, the delivery device  850  may be configured such that the distal portion of the delivery device  850  may have a diameter less than or equal to about 10 mm. The clip  800  and delivery device  850  may be formed from any suitable materials, such as one or more of medical grade, high-strength plastics or metals, such as stainless steel, cobalt chromium, PEEK, one or more nylons, polyimide, or the like, and/or may be at least partially formed from magnetic materials, as described herein. Additionally, in some variations, the suction cup  802  may be formed from a deformable or flexible material, which may allow the suction cup  802  to deform to accommodate irregular tissue. For example, in some variations the suction cup  802  may be formed from one or more rubbers (e.g., silicon, one or more thermoset elastomers) or urethanes. 
     In the embodiment of the grasper  800  shown in  FIGS. 8A and 8B , the grasper  800  may be configured to releasably adhere to tissue using suction. As shown in  FIGS. 8A and 8B , the grasper  800  may comprise a suction cup  802 , a tube  804 , and a piston  806  slidably moveable within the tube  804  and connected to a piston rod  808 . Generally, the tube  804  may have a lumen extending therethrough. The distal opening  815  of the tube  804  may connect to an opening  812  through the suction cup  802 , which may allow the piston  806  to displace air from or draw air through the suction cup  802 . Specifically, advancement of the piston  806  may push air out of the tube  804  and out of the suction cup  802 . Conversely, retraction of the piston  806  may draw air through the suction cup  802  and the tube  804 . 
     To connect the grasper  800  to tissue, the piston  806  may be advanced to evacuate air from the tube  804  out of the suction cup  802 , and the suction cup  802  may be positioned against tissue. With the suction cup  802  positioned against tissue, the piston  806  may be at least partially retracted. This may create a vacuum, as the presence of the tissue in the suction cup  802  may prevent air from passing into the tube  804  through the suction cup  802 . Accordingly, the section cup  802  may instead provide a vacuum force to the tissue. This vacuum force may hold the grasper  800  against the tissue. To release the grasper  800  from tissue, the piston  806  may be advanced to remove the vacuum force. 
     The proximal end of the piston rod  808  may have an attached linking element  810 , which may allow the grasper  800  to be engaged by the delivery device  850 , as describe in more detail herein. The linking element  810  may comprise a magnetic or ferromagnetic material, such as, for example, stainless steel, iron, cobalt, nickel, neodymium iron boron, samarium cobalt, alnico, ceramic ferrite, alloys thereof and/or combinations thereof. In addition to allowing for engagement with the delivery device  850 , the linking element  810  may allow the grasper  800  to be manipulated by the magnetic control assembly. 
     Generally, the suction cup  802  may be configured to promote connection of the grasper  800  to tissue. For example, the suction cup  802  may be formed from a shape that defines a cavity configured to at least partially receive tissue. In some variations, the suction cup  802  may have a hemispherical or a conical shape. Additionally or alternatively, the suction cup  802  may comprise one or more tabs or other protrusions that may be configuration to at least partially wrap around tissue. In these variations, the tabs/protrusions may engage tissue and may help to hold it temporarily in place. The volume of the tube  804  and size of the suction cup  802  may be chosen based on the desired suction strength; a larger tube and/or suction cup may allow the grasper  800  to have greater negative pressure adhering the grasper  800  to the tissue. 
     The grasper  800  may be delivered and actuated by any delivery device that is configured to reversibly withdraw the piston  806  of the grasper  800  to create suction to hold the grasper  800  to tissue. In one variation shown in  FIGS. 8A-8B , the delivery device  850  may comprise an elongate sheath  854  and an actuation rod  852 . The actuation rod  852  may have a delivery linking element  858  at its distal end and a piston actuator  860  at its proximal end, and may be slidably disposed in a elongate sheath  854 . The actuation rod  852  may be advanced through the lumen  856  of the elongate sheath  854  to hold and actuate a grasper (such as the grasper  800  shown in  FIGS. 8A-8B ), as will be discussed in more detail herein. 
     The delivery linking element  858  may be configured to releasably couple the delivery device  850  to the grasper  800  via magnetic attraction between the delivery linking element  858  and the linking element  810  of the grasper  800  described herein. At least a portion of the delivery linking element  858  may comprise one or more materials which may be attracted to a magnetic field. These materials may include one or more magnetic or ferromagnetic materials, such as, for example, stainless steel, iron, cobalt, nickel, neodymium iron boron, samarium cobalt, alnico, ceramic ferrite, alloys thereof and/or combinations thereof. The delivery linking element  858  may be movable between an advanced position (as shown in  FIG. 8B ) and a retracted position (as shown in  FIG. 8A ). When the delivery linking element  858  of the delivery device  850  is brought in proximity to the linking element  810  of the grasper  800 , the delivery linking element  858  of the delivery device  850  may engage linking element  810  of the grasper  800  via magnetic attractive force. When the grasper  800  and  850  are engaged, retracting and advancement of the actuation rod  852  relative to the tube  804  and suction cup  802  of grasper  800  may create suction to adhere the suction cup  802  to tissue. With the suction cup  802  of the grasper  800  pressed against tissue, the actuation rod  852  may be moved proximally relative to the suction cup  802  and tube  804 , which may create a negative pressure within the suction cup  802  and tube  804 . After the grasper  800  is attached to tissue, a magnetic force may be applied to the grasper  800  by the magnetic control element to manipulate the attached tissue. 
     In order for releasable engagement of the delivery linking element  858  of the delivery device  850  and the linking element  810  of the grasper  800 , delivery device  850  may further comprise a depth stop that may prevent linking element  810  from moving proximal to a certain point within lumen  856  of elongate sheath  854 . Thus, if actuation rod  852  is moved proximally beyond the depth stop, the force from the depth stop on the linking element  810  may overcome the engagement force connecting the delivery linking element  858  and the linking element  810  (e.g., a magnetic attractive force), and the delivery linking element  858  and the linking element  810  may disengage. In some variations (not shown), the depth top may comprise an inner sheath. The inner sheath may be sized such that the delivery linking element  858  can fit within the inner sheath, but the linking element  810  cannot. Thus, if the actuation rod  852 , and thus the delivery linking element  858 , are withdrawn proximally relative to and within the inner sheath, the linking element  810  of clip  100  may not be able to move proximally beyond the distal end of the inner sheath, and thus the distance between the delivery linking element  858  and the linking element  810  may increase. Because force applied by a magnet decreases as the function of the distance from the magnet, increasing this distance may decrease the magnetic attractive force felt between the delivery linking element  858  and linking element  810 . Eventually, the attractive force may be sufficiently diminished such that the delivery linking element  858  may decouple from the linking element  810 . If desirable, the delivery device  850  may subsequently reengage the clip  800  to disconnect the clip  800  from tissue and/or reposition the clip  800 . 
     In some variations, instead of a depth stop for releasable engagement of the delivery linking element  858  of the delivery device  850  and the linking element  810  of the grasper  800 , delivery device  850 , either the delivery linking element  858  or the delivery device  850  may comprise an electromagnet. The electromagnet may comprise an active configuration and an inactive configuration. The electromagnet may be activated in order to allow the delivery linking element  858  and delivery device  850  to releasably engage. Conversely, the electromagnet may be inactivated to allow the delivery linking element  858  and delivery device  850  to disengage. Additionally, although the system of  FIGS. 8A-8B  relies on magnetic attraction to couple the grasper  800  and delivery device  850 , it should be appreciated that in some variations the delivery device  850  may comprise another attachment mechanism, such as a threaded rod that may be screwed onto the grasper tube end. 
     In addition to clip- or clamp-like grasping devices and suction-based devices, a system may include a wire having a pre-formed shape that may be configured to ensnare or otherwise engage tissue.  FIGS. 9A-9B  show perspective views of such a system comprising a wire  900  and a delivery device  950 . The wire  900  may be deployed to wrap around or otherwise attach to tissue. In some variations, the wire  900  may be pre-shaped into a configuration configured to wrap around or otherwise attach to tissue, such as a coil, as shown in  FIG. 9B . Generally, at least a portion of the wire  900  may be formed from one or more metallic or magnetic materials which may be attracted to a magnetic field, as described in more detail herein. The materials may include one or more magnetic or ferromagnetic materials, such as, for example, stainless steel, iron, cobalt, nickel, neodymium iron boron, samarium cobalt, alnico, ceramic ferrite, alloys thereof and/or combinations thereof. Having at least a portion of the wire  900  formed from one or more metallic or magnetic materials that may be attracted to a magnetic field may allow the wire  900  to be manipulated by the magnetic control assembly. 
     The delivery device  950  may comprise a shaft  952  configured to hold the wire  900  in a straightened configuration. The wire  900  may be inserted into the patient, for example through a laparoscopic port, while housed in the shaft  952 . After the wire  900  is located near the target tissue, the wire  900  may be advanced distally out of the shaft  952 , as shown in  FIG. 9B . This may cause the wire to assume its pre-shaped configuration, which may allow it to attach to tissue. While the pre-shaped configuration is shown in  FIG. 9A  as being a coil  902 , the wire may have any suitable shape configured to ensnare tissue. The wire may be fully deployed from the shaft  952 , after which the shaft  952  may be removed from the patient. When the wire  900  has ensnared tissue, a magnetic force may be applied to the wire  900  by the magnetic control assembly, thus manipulating the attached tissue. 
     Magnetic Control Assembly 
     Once attached to tissue within the patient&#39;s body, the grasper may be manipulated by a magnetic control assembly. Generally, the magnetic control assembly may be configured to be placed outside a patient&#39;s body and to produce a magnetic field. The magnetic field produced by the magnetic control assembly may provide one or more forces to the magnetic device to control the position of the magnetic device. The magnetic control assembly may comprise at least one magnet configured to generate a magnetic field and at least one force modulation device. The force modulation device may control the magnitude of the force applied to the magnetic device. 
     In some embodiments, the force modulation device may comprise an adjustable shielding device, which may be configured to alter the magnetic field produced by the magnetic control assembly. Additionally or alternatively, the force modulation device may be configured to control a distance between the magnetic device and at least one magnet of the magnetic control assembly, which in turn may modulate the force applied to the magnetic device by the magnetic control assembly. In yet other embodiments, the force modulation device may be configured to both alter the magnetic field produced by the magnetic control assembly and control the distance between the magnetic control assembly and the magnetic device. In some variations, the magnetic control assemblies may comprise all or a portion of those described in U.S. application Ser. No. 14/200,302, filed on Mar. 7, 2014, and titled “Magnetic Control Assemblies and Systems Therefor.” the contents of which are hereby incorporated by reference in their entirety. 
       FIG. 10  shows an illustrative variation of a magnetic control assembly. As shown there, in one variation the magnetic control assembly  1000  may comprise a mounting device  1002 , a magnet  1004 , and a force modulation device  1006 . Although shown with a force modulation device, it should be appreciated that the magnetic control assembly  1000  need not comprise a force modulation device  1006 . Similarly, the magnetic control assembly  1000  need not comprise a mounting device  1002 . 
     The magnet  1004  may be configured to generate a magnetic field, such that when the magnetic control assembly  1000  is positioned near a patient  1008 , the magnetic field may be generated inside the patient  1008 . This magnetic field may apply a force to and manipulate a grasper  1010  positioned in the body. In some variations, the magnet  1004  may comprise one or more permanent magnets and/or one or more electromagnets. The magnet  1004  may comprise any number of individual magnets, which in some instances may be formed in an array. The magnet  1004  may have any suitable size and shape, such as cylindrical shape having a circular, oval, or semi-circle cross-section, a bar magnet having a rectangular or triangular cross section, a spherical magnet, or the like. 
     Generally, the mounting device  1002  may be configured to mount the magnetic control assembly  1000  to one or more structures (e.g., a wall, ceiling, an operating table, or the like). In some instances, the mounting device  1002  may be further configured to counterbalance the weight of the magnet  1004  and the force modulation device  1006 , such that the magnet  1004  and the force modulation device  1006  may be moveably suspended by the mounting device  1006 . With the magnetic control assembly  1000  suspended by the mounting device  1002 , an operator may move the magnet  1004  and/or force modulation device  1006 . Additionally or alternatively, the force modulation device  1006  may alter the positioning of the magnet  1004 . In some variations, the position of the mounting device  1002  may be temporarily locked to fix the positions of the magnet  1004  and/or force modulation device  1006 . 
     The force modulation device  1006  may be configured to modulate the strength of the magnetic field applied to a grasper  1010  positioned in the body. For example, in some instances it may be desirable to suspend the grasper  1010  against a tissue wall (e.g., the abdominal wall) while limiting the force that the grasper  1010  applies to the tissue wall. Accordingly, by modulating the strength of the magnetic field applied to the grasper  1010 , the magnetic control assembly  1000  may control the force applied to the grasper  1010 , which in turn may control the pressure applied by the grasper  1010  to the tissue wall. In some variations, the magnetic control assembly  1000  may comprise force modulation device  1006  that comprises an adjustable shielding device, which may alter the magnetic field produced by the magnet  1004  of the assembly. In other variations, the force modulation device  1006  may comprise a distance adjustment device, which may alter the distance between the magnet  1004  of the assembly and a grasper  1010  positioned in the body. In still other variations, the force modulation device  1006  may comprise an adjustable shielding device that is also configured to alter the distance between the magnet  1004  of the assembly  1000  and a grasper  1010  positioned in the body. 
     In some embodiments, the force modulation device  1006  may be controlled by an automated feedback loop based on a sensor located in the grasper  1010 . This sensor may provide feedback, which is may be used by the magnetic control assembly to modulate the force applied to the grasper. In some variations of the graspers described here, the grasper may comprise at least one sensor. In some variations, the grasper may comprise a magnetometer configured to measure the strength of the magnetic fields applied to grasper. In these variations, the magnetometer may comprise a scalar magnetometer configured to measure a total strength of the magnetic field applied thereto or may comprise a vector magnetometer configured to measure the strength of a magnetic field in a particular direction. In some instances, a grasper may comprise a plurality of vector magnetometers configured to measure the strength of a magnetic field in multiple directions (e.g., along two axes, along three axes, or the like). 
     Additionally or alternatively, in some variations, the graspers described here may comprise a pressure sensor configured to measure pressure applied to one or more surfaces of the grasper. For example, when the grasper is pulled against an abdominal wall of a patient, the pressure sensor may be configured to measure the pressure between the grasper and the abdominal wall. It may be desirable to limit this pressure, as too much pressure applied to the abdominal wall may block blood flow thereto and possibly cause tissue necrosis. The grasper may comprise any combination of pressure sensors and magnetometers. When a grasper comprises at least one sensor, the grasper may be configured to communicate data from the sensor or sensors to the magnetic control assembly. In some variations, the grasper may be configured to communicate this data wirelessly. Additionally or alternatively, the grasper may be configured to produce one or more signals which may be used by the magnetic control assembly to determine a relative positioning between the grasper and the magnetic control assembly. 
     Methods 
     As mentioned above, the graspers described here may be used to provide remote suspension of tissue during a minimally-invasive procedure. Generally, to provide suspension of a tissue, a grasper as described herein may be advanced into the body, may be releasably connected to a tissue in the body, and may be suspended using one or more magnets positioned externally to the body to move and suspend the tissue. In some variations, the grasper may be detached from the tissue, and the grasper may be repositioned and reconnected to tissue (either the same tissue or different tissue). 
     The grasper, such as any of the graspers described herein, may be advanced into the body in any suitable manner. In some variations, the grasper may be advanced into the body through a laparoscopic port as part of a laparoscopic procedure. In some instances, the laparoscopic procedure may be a single-incision laparoscopic procedure. In some variations, the grasper may be advanced into the body using a delivery device, such as any of the delivery devices described herein. In these variations, the grasper may be releasably coupled to a distal engagement portion of the delivery device, and the distal engagement portion of the delivery device may be advanced into the body to advance and position the grasper within the body. 
     Once the grasper is positioned in the body, it may be releasably connected to tissue. To connect the grasper to tissue, the grasper may first be placed in an open configuration. In some variations, the grasper may be placed in an open configuration using the delivery device carrying the grasper, as described with respect to each system herein. With the grasper in the open configuration, the grasper may be manipulated to position the tissue between the first jaw and the second jaw. The grasper may be returned to a closed configuration. The grasper may then be released from the delivery device, which may be removed from the body in some variations. With the grasper releasably connected to the tissue, a magnetic control element comprising one or more magnets may be positioned externally of the body and may magnetically attract the grasper to reposition and/or hold the grasper. 
     In some instances it may be desirable to detach the grasper from the tissue. For example, in some instances it may be desirable to attach the grasper to a different portion of the tissue. In these instances, the grasper may be detached from the tissue using a delivery device to return the grasper to an open configuration. The grasper may be repositioned to again place tissue between the jaws of the grasper, and the grasper may then be placed in the closed configuration to reattach the grasper to tissue. In other instances, the grasper may be detached from the tissue, and removed from the body.