Electrically weldable suture material, and apparatus and method for forming welded suture loops and other welded structures

Abstract

To provide a device for positioning in the body of an animal.SOLUTION: A device comprises a first portion and a second portion that may be positioned in contact with one other, the first portion and the second portion each comprising a biocompatible conductive thermoplastic material, such that when the device is positioned in the body of an animal and electric current flows from the first portion to the second portion, heat is generated by electrical resistance at the point of contact between the first portion and the second portion so as to melt regions of the first portion and the second portion, and when the electric current is thereafter terminated, the melted regions of the first portion and the second portion re-solidify so that a weld is formed between the first portion and the second portion.SELECTED DRAWING: Figure 2B

Description

[Technical Field]

[0001] REFERENCE TO PRIOR PENDING PATENT APPLICATIONS This patent application claims the benefit of pending prior U.S. Provisional Patent Application No. 62 / 586,108, filed November 14, 2017, by Thomas Egan for "ELECTRICALLY WELDABLE SUTURE MATERIAL, APPARATUS AND PROCESS FOR FORMING WELDED SUTURE LOOPS AND OTHER STRUCTURES" (Attorney Docket No. US-7495-2P2), which is incorporated herein by reference.

[0002] The present invention relates to the use of electrical energy to fuse polymeric materials into useful shapes, more particularly to the use of electrical energy to fuse polymeric materials into useful shapes within the body of an animal (which term is intended to include humans and other mammals), and even more particularly to the use of electrical energy to fuse polymeric sutures and other structures for the surgical joining of tissues within the body, such as for surgical suturing and vascular or organ closure. [Background technology]

[0003] In surgical procedures, sutures are typically used to secure tissue edges together and maintain them in proximity to one another until healing is substantially complete. The suture is generally directed through the portions of the tissue to be joined and formed into a single loop or stitch, which is then knotted or otherwise secured (e.g., with a crimped fastener) to maintain the tissue edges in the proper relationship to one another for healing to occur.

[0004] In some situations, a series of individual, separate stitches of substantially uniform tension are created in the tissue. Because the stitches are individual and separate from one another, removal of one stitch does not require removal of all of the stitches or cause the remaining stitches to loosen. However, each individual stitch requires an individual knot (or some other stitch closure device, e.g., a crimped fastener) to secure the stitch in place around the wound.

[0005] For example, it may be necessary or desirable to close a wound with sutures without having to tie knots in the sutures or utilize loop closure devices (e.g., crimped fasteners), such as in surgical repair of organs or tissues where access to the repair site is limited. In these situations, fused suture loops may be used to maintain the wound edges sufficiently proximal for a period of time sufficient to allow healing to occur.

[0006] Polymeric sutures are particularly suited to various fusion or joining processes, such as, for example, welding, in which sections of the suture can be fused together by applying sufficient heat to the sections to cause partial melting and fusing of the sections.

[0007] Previous efforts have been made to fuse segments of polymeric sutures using either (i) the direct application of heat or (ii) the application of ultrasonic energy.

[0008] Unfortunately, achieving welding via the direct application of heat suffers from two significant disadvantages. First, the direct application of heat to the suture in situ can create undesirable heating of the surrounding tissue. Second, it is difficult to selectively melt only the interface between the suture segments to be welded by the direct application of heat to the suture without melting the entire cross-section of the suture, which can dramatically weaken the suture.

[0009] For these reasons, it is generally preferred to apply non-thermal energy to the suture material in situ to induce localized heating of the suture material in the area or section to be fused. In particular, ultrasonic energy can be effectively applied to sections of suture material to induce frictional heating of the sections to fuse or weld them together. While such ultrasonic welding of sutures can be a significant improvement over direct thermal welding of sutures (i.e., ultrasonic welding melts only the portions of the suture that touch each other, not the entire cross-section of the suture), thereby preserving the strength of the suture, ultrasonic welding suffers from two significant disadvantages of its own. First, ultrasonic welding requires bulky and expensive equipment. Such equipment may be incompatible with certain types of surgical procedures and, in either case, increases costs. Second, due to the nature of the ultrasonic transducer and waveguide, ultrasonic welding requires a straight line of access between the energy source and the weld site, making it incompatible with curved or flexible instruments. Summary of the Invention [Problem to be solved by the invention]

[0010] It is therefore an object of the present invention to provide a new and improved approach to forming connections (which may also be referred to as joints or welds) in the body that does not suffer from the problems associated with the prior art. [Means for solving the problem]

[0011] The present invention involves the provision and use of a new and improved approach for forming connections (which may also be referred to as joints or welds) in the body that does not suffer from the problems associated with the prior art.

[0012] Among other things, the present invention involves the provision and use of new and improved methods and apparatus for producing suture welds of sufficient strength and reliability to replace suture knots or other loop closure devices.

[0013] One important aspect of the present invention involves the provision and use of a new class of polymeric biomaterials that are strong, biologically compatible, and weldable using electrical energy (i.e., "electrically weldable polymers").

[0014] Another important aspect of the present invention is the provision and use of methods for joining polymeric devices within the body to create medically useful structures.

[0015] And, another important aspect of the present invention is the provision and use of devices for delivering and joining medically useful structures within the body.

[0016] Yet another important aspect of the present invention is the provision and use of novel medically useful structures including, but not limited to, (i) fused loops of electrically weldable polymers, (ii) welded hemostatic clips of electrically weldable polymers, and (iii) continuously deliverable staple-like chains of electrically weldable polymer fasteners.

[0017] In one form of the invention, there is provided a device for positioning within an animal's body, the device comprising a first part and a second part, the first part and the second part being positionable in contact with one another, the first part and the second part each comprising a biocompatible, electrically conductive thermoplastic material, such that when the device is positioned within the animal's body and when an electric current flows from the first part to the second part, heat is generated by electrical resistance at the point of contact between the first part and the second part, melting regions of the first part and the second part, and when the electric current is subsequently stopped, the melted regions of the first part and the second part re-solidify and a weld is formed between the first part and the second part.

[0018] In another form of the invention, there is provided an apparatus for forming a weld between a first portion of a biocompatible conductive thermoplastic material and a second portion of a biocompatible conductive thermoplastic material, the apparatus comprising: a first electrode; a second electrode; and a structure for holding the first and second electrodes opposite each other with a space between the first and second electrodes to receive the first and second portions in contact with each other, the structure being non-conductive. an electrical circuit including a power supply and a switch arranged such that closing the switch applies an electrical potential across the first and second electrodes, the first and second portions being positioned within an animal's body and placed in contact with one another between the first and second electrodes, such that when the switch is subsequently closed, heat is generated by electrical resistance at the point of contact to melt a region of the first and second portions, and when the switch is subsequently opened, the melted portions of the first and second portions re-solidify and a weld is formed at the point of contact.

[0019] In another form of the invention, there is provided a method for forming a weld between two pieces of biocompatible conductive thermoplastic material in an animal body, the method comprising the steps of: positioning first and second pieces of biocompatible conductive thermoplastic material in the animal body between first and second electrodes, such that the first piece is in contact with the first electrode, the second piece is in contact with the second electrode, and the first and second pieces of biocompatible conductive thermoplastic material are in contact with each other; applying a selected amount of current across the first and second electrodes to generate a selected amount of heat by electrical resistance at the point of contact between the first and second pieces, causing a specific desired amount of melting of the first and second pieces; and terminating the current across the first and second electrodes, such that the melted regions of the first and second pieces re-solidify and a weld is formed at the point of contact.

[0020] In another form of the invention, there is provided an end effector for a suturing device, the end effector including: a first arm having a tissue engaging surface; and a second arm having a tissue engaging surface, at least one of the first and second arms (i) configured for movement toward the other of the first and second arms to clamp tissue between the tissue engaging surface of the first arm and the tissue engaging surface of the second arm, and (ii) configured for movement away from the other of the first and second arms to release tissue clamped between the tissue engaging surface of the first arm and the tissue engaging surface of the second arm, the second arm having an opening therein, and the end effector and (ii) a needle having a piercing tip configured for movement toward the tissue engaging surface of the first arm to position the piercing tip adjacent the tissue engaging surface of the first arm to thereby pierce tissue clamped between the tissue engaging surface of the first arm and the tissue engaging surface of the second arm, and (iii) a needle configured for movement away from the tissue engaging surface of the first arm to withdraw tissue clamped between the tissue engaging surface of the first arm and the tissue engaging surface of the second arm, wherein the needle is configured to pierce a tissue in the second arm as the needle is moved toward the tissue engaging surface of the first arm. An end effector is provided that is configured to pass through the opening and also to pass through the opening in the second arm when the needle moves away from the tissue engaging surface of the first arm.

[0021] These and other objects and features of the present invention will be more fully disclosed or made apparent by the following detailed description of preferred embodiments of the invention, which should be considered in conjunction with the accompanying drawings, in which like numerals represent like parts, and in which: [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a schematic diagram showing a short length of filamentary material formed in accordance with the present invention (the filamentary material may be referred to herein as an "electrically conductive thermoplastic suture"); [Figure 2A] 1 is a schematic diagram illustrating a novel apparatus for welding conductive thermoplastic sutures. [Figure 2B] 2B is a schematic diagram illustrating the formation of a weld in an electrically conductive thermoplastic suture using the novel apparatus of FIG. 2A. [Figure 3] 1 is a schematic diagram illustrating a tissue fastening device or construct formed in accordance with the present invention. [Figure 4A] FIG. 1 is a schematic diagram illustrating a novel device made from molded conductive thermoplastic material that is intended to be electrically welded in situ. [Figure 4B] FIG. 1 is a schematic diagram illustrating a novel device made from molded conductive thermoplastic material that is intended to be electrically welded in situ. [Figure 5A] FIG. 1 is a schematic diagram illustrating another novel device made from molded conductive thermoplastic material that is intended to be electrically welded in situ. [Figure 5B] FIG. 1 is a schematic diagram illustrating another novel device made from molded conductive thermoplastic material that is intended to be electrically welded in situ. [Figure 6] 1 is a schematic diagram illustrating a novel suturing instrument for use in surgery. [Figure 7A] FIG. 7 is a schematic diagram showing the distal end effector portion of the novel suturing instrument of FIG. 6. [Figure 7B] FIG. 7B is a schematic diagram illustrating the actuation of the grasper portion of the distal end effector shown in FIG. 7A. [Figure 7C] FIG. 10 is a schematic diagram showing a needle (with grooves) advanced through tissue (not shown) sandwiched between the gripping surfaces of the distal end effector. [Figure 7D] FIG. 7D is a schematic diagram showing the distal end effector of FIG. 7C with the suture advanced by forcing the suture into the needle and grasper grooves. [Figure 7E] FIG. 7E is a schematic diagram illustrating the actuation of the articulated gripping mechanism of the distal end effector of FIG. 7D. [Figure 7F] FIG. 7F is a schematic diagram showing the distal end effector of FIG. 7E with the needle retracted and the suture advancement mechanism reversed. [Figure 7G] FIG. 7F is a schematic diagram showing the distal end effector of FIG. 7F advanced so that the electrodes contact a portion of the suture. [Figure 7H] FIG. 7H is a schematic diagram showing the distal end effector of FIG. 7G with the knife blade advanced to cut the suture. [Figure 7I] FIG. 7C is a schematic diagram showing the distal end effector of FIG. 7H with the graspers in a reopened position. [Figure 8A] FIG. 1 is a schematic diagram illustrating a novel end effector for use in robotic surgery. [Figure 8B] FIG. 1 is a schematic diagram illustrating a novel end effector for use in robotic surgery. [Figure 8C] FIG. 8C is a schematic diagram showing further details of the novel end effector shown in FIGS. 8A and 8B. [Figure 8D] FIG. 8C is a schematic diagram showing further details of the novel end effector shown in FIGS. 8A and 8B. [Figure 8E] FIG. 8C is a schematic diagram showing further details of the novel end effector shown in FIGS. 8A and 8B. [Figure 8F] FIG. 8C is a schematic diagram showing further details of the novel end effector shown in FIGS. 8A and 8B. [Figure 9A] 8C is a schematic diagram illustrating anatomic closure achieved by the novel end effector shown in FIGS. 8A and 8B. FIG. [Figure 9B] 8C is a schematic diagram illustrating anatomic closure achieved by the novel end effector shown in FIGS. 8A and 8B. FIG. [Figure 9C] 8C is a schematic diagram illustrating anatomic closure achieved by the novel end effector shown in FIGS. 8A and 8B. FIG. [Figure 9D] 8C is a schematic diagram illustrating anatomic closure achieved by the novel end effector shown in FIGS. 8A and 8B. FIG. [Figure 9E] 8C is a schematic diagram illustrating anatomic closure achieved by the novel end effector shown in FIGS. 8A and 8B. FIG. [Figure 10A] FIG. 1 is a schematic diagram illustrating another novel end effector for use in robotic surgery. [Figure 10B] FIG. 10B is a schematic diagram illustrating anatomic closure achieved by the novel end effector shown in FIG. 10A. [Figure 10C] FIG. 10B is a schematic diagram illustrating anatomic closure achieved by the novel end effector shown in FIG. 10A. [Figure 10D] FIG. 10B is a schematic diagram illustrating anatomic closure achieved by the novel end effector shown in FIG. 10A. [Figure 10E] FIG. 10B is a schematic diagram illustrating anatomic closure achieved by the novel end effector shown in FIG. 10A. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention involves the provision and use of new and improved methods and apparatus for producing suture welds of sufficient strength and reliability to replace (or enhance the strength of) suture knots or other loop closure devices.

[0024] This disclosure describes the inventive concepts with reference to particular examples, but the intent is to cover all modifications, equivalents, and alternatives of the inventive concepts consistent with this disclosure.

[0025] The Invention Generally Forming surgical stitches in anatomical regions with difficult surgical access is a challenge in minimally invasive surgery. The present disclosure describes an invention that joins sutures by welding (e.g., instead of tying or knotting), which saves time and can be done in extremely tight spaces. Unlike existing suture welding systems, the present invention is capable of delivering suture welds through tortuous paths (e.g., through curved catheters, etc.) using low-cost welding equipment. The disclosed aspects of the invention may be particularly beneficial to manufacturers of robotic surgical systems. For example, fully automated suturing device accessories may be utilized in surgical robotic systems.

[0026] Traditional "needle and thread" suturing requires manual or instrument access, which is time consuming, requires maneuvering space, and leaves bulky knots at the surgical site. Crimp-type joining devices leave foreign material (e.g., a metal crimp) at the joining site, and the high crimp force required to actuate the crimp requires a significant shaft diameter and limited shaft length.

[0027] Existing suture welding devices that utilize the direct application of heat risk undesirable heating of surrounding tissue and / or weakening of the suture. Existing ultrasonic suture welding devices are bulky, expensive, and require linear access to the surgical site. Existing surgical robotic manipulators are time-consuming, require maneuvering space, and have a steep learning curve.

[0028] Traditionally, formed sutures are passed through tissue with a needle and tied into a loop with a knot to close the wound and allow the tissue to heal. Minimally invasive surgery (MIS) and robotic surgery place high demands on the surgeon's skills due to the need to tie suture knots in areas of the body that are difficult for the surgeon to access. Many surgical instruments have been developed to assist surgeons in tying knots or to provide knot substitutes. Such instruments have been invented by the present inventor and others. One known instrument includes a tool for forming a welded loop of suture, while another considers the welded loop of suture itself as a surgical fastener. While this method of joining sutures to stitches facilitates suturing in areas of the body that are difficult to access, in practice it requires an ultrasonic generator, a transducer, and a waveguide to complete the weld in the monofilament suture. This device is bulky, expensive, and requires direct access from the point of incision to the surgical site.

[0029] The present invention seeks to improve upon these previous inventions through the use of novel suture materials and novel welding devices that can be delivered through slender and / or curved shafts without the need for bulky and costly ultrasonic equipment.

[0030] Novel aspects of the disclosed invention include, among others: 1. a suture material that is directly weldable using small amounts of simple low voltage electrical energy, 2. a tissue fastening device or construct comprising a continuous welded loop of filamentary material comprised of an electrically weldable polymer, 3. an apparatus for welding electrically weldable sutures that provides precise control over welding parameters to ensure consistent, high strength welds, 4. an apparatus for welding electrically weldable sutures that can operate safely inside the body without damaging adjacent tissue, and 5. an apparatus for welding electrically weldable sutures that can be delivered to remote areas of the body through tortuous paths.

[0031] These and other benefits may be realized by the novel materials, apparatus, methods, and devices of the present invention.

[0032] The suture material embodiments of the present invention are made from filaments of conductive, biocompatible material with diameter, strength, and flexibility consistent with surgical sutures, as well as predictable resistivity.

[0033] Device aspects of the present invention include a mechanism for holding the overlapping portion of the suture loop, a mechanism for applying contact pressure through the overlapping region, and a mechanism for applying and controlling electrical current through the overlapping region, where the electrical current passing through the overlapping region causes localized heating of the overlapping region, thereby causing localized melting of the overlapping region, which then re-solidifies to form a weld.

[0034] Some versions of the device further include a mechanism for clamping the suture to maintain suture tension during the welding process, a mechanism for trimming the suture tail that extends beyond the suture loop, a handle with controls to allow a user (e.g., a surgeon) to steer the device and initiate the welding process, and an elongated straight, curved, articulating, flexible, and / or steerable shaft that connects the distal welding device to the proximal handle and allows the user to steer the welding device into areas of the body with difficult access (e.g., such as in an MIS procedure).

[0035] Further versions of the device include means for controllably or automatically penetrating tissue, threading the suture, tensioning the suture, trimming the suture tails, and releasing the formed tissue-fastening suture loop. Examples of these means are disclosed in the inventor's prior U.S. Patent No. 5,417,700 (which patent is incorporated herein by reference) and can be used individually or in combination with this new welding device.

[0036] The welding process aspects of the present invention share many characteristics in common with resistance or spot welding of metals, with some important novel distinctions, including, but not limited to, the advantages of: low voltage and special electrical insulation; the ability to work with non-metallic conductive materials; and a means to control the localization and depth of the material melt so as to preserve the high strength of the highly linearized molecular chains of the conductive polymer or composite material being welded.

[0037] The suture loops formed by the materials, apparatus, and processes disclosed herein are tissue fastening devices or constructs in the form of continuous loops formed in situ, comprising a filament of the biocompatible electrically conductive material disclosed herein, arcing in a generally circular configuration, with overlapping regions joined by welds.

[0038] Other structures are also disclosed herein that are made from the disclosed materials and welded in situ, but do not necessarily include filamentary material in the form of loops or of uniform cross-section.

[0039] Materials Used to Form Weldable Sutures and / or Weldable Structures Figure 1 shows a short length of filamentary biocompatible material 5. In one version of the invention, material 5 has the properties of being substantially round in cross section and of having suture diameter (USP 29-861) and tensile strength (USP 29-881) within the ranges established by the United States Pharmacopoeia and equivalent international standards. Material 5 further has the properties of being electrically conductive with a known resistivity and being meltable with a melting temperature above 37°C (so that material 5 becomes a solid in the human body). Thus, material 5 comprises an electrically conductive thermoplastic material.

[0040] In a preferred form of the invention, material 5 is a monofilament of a thermoplastic polymer compounded with a conductive additive. In some versions, a dispersing agent is used to ensure uniform mixing of the conductive additive within the polymer matrix. In some versions, the thermoplastic base polymer and conductive additive (and, if needed, a dispersing agent) are melt compounded (blended), extruded, and drawn to create a monofilament with substantially linear molecular chains for superior strength and flexibility. In other versions, the melt compounded (blended) material is injection molded into a single or multi-part device for medical use. In some versions, the thermoplastic polymer is a bioabsorbable material currently approved for use as a suture or implant material (e.g., polylactic acid (PLA), polyglycolide (PGA), polydioxanone (PDS), thermoplastic linear polyesters such as those sold under the trademark TephaFLEX™, etc.). In other versions, the thermoplastic polymer is a nonabsorbable material (e.g., nylon, polypropylene, polycarbonate, etc.). In some versions, the conductive additive is an inert and / or non-toxic material, such as carbon black, carbon fiber, iron oxide (FeO and others), or metal powder or nanoparticles. In other versions, the conductive additive is any one of intrinsically conductive polymers (ICPs), including, but not limited to, polyacetylene, polyaniline, polythiophene, and polyphenylene vinylene. In some versions, these non-thermoplastic polymers are composited with a thermoplastic base polymer. In other versions, the non-thermoplastic polymer is applied as a film coating to a base polymer filament or part. In some versions, the conductive coating is a continuous or patterned coating of conductive ink. In some versions, a conductive polymer or composite may be coextruded onto another, not necessarily conductive polymer, core. In some versions, the core material has a higher melting temperature than the coextruded outer layer.In other versions, the filament can be a multi-strand structure, such as a braided suture made from a bundle of microfilaments of a conductive thermoplastic polymer, or a composite of different filaments braided together. In one version, conductive and non-conductive filaments are combined into a single braided suture. In another embodiment, varying melting temperature and conductive microfilaments are braided together so that localized weld melting does not melt the higher melting temperature filaments, thereby preserving their highly linearized molecular orientation and high strength properties and creating a strong weld region. In one version, high-strength, high-melting temperature polymer filaments are provided in a low-melting temperature metal matrix so that when an electric current is applied through adjacent portions of the polymer filament / metal matrix, the metal fuses but leaves the high-strength filaments intact. In yet another version, a metal suture or wire is used, but pure metal is generally less desirable than a conductive thermoplastic. This is because the high melting temperature of metals and the high thermal conductivity in metals pose a risk of damage to surrounding tissue, and melt spreading in metals is more difficult to control than melt spreading in polymers. In some versions of the material, the material filaments have transverse (side-to-side) electrical conductivity but not axial (end-to-end) electrical conductivity, which has the benefit of protecting the body from stray currents in the event of suture breakage before or during welding. The transverse, but not axial, conductive characteristic can result from stretching or drawing the composite with a low conductive additive fill ratio. This is because the additive chains are broken axially during drawing but can be compacted transversely due to diameter reduction.

[0041] In one form of the invention, material 5 is an electrically conductive thermoplastic polymer.

[0042] Apparatus for Welding Conductive Thermoplastic Sutures FIG. 2A illustrates an apparatus 10 for welding a length of conductive thermoplastic suture 15. The length of conductive thermoplastic suture 15 includes a first end 20 and a second end 25. The first end 20 and the second end 25 overlap at a contact point 30 to form a loop of suture 15. The loop of suture 15 is held in the loop configuration by a clamping mechanism 35 applied at contact point 30. The clamping mechanism 35 includes a first electrode 40 conforming to a surface of the first end 20 of the suture 15 and a second electrode 45 conforming to a surface of the second end 25 of the suture 15. A spring 50 applies a predetermined force between the electrodes 40 and 45 to maintain pressure at the contact point 30. In one version, the first electrode 40 and the second electrode 45 are disposed substantially parallel to one another, resulting in line contact between the first suture end 20 and the second suture end 25 (not shown). In another version (i.e., the version shown in FIG. 2A), there is a relative curvature between the first electrode 40 and the second electrode 45, resulting in point contact between the first suture end 20 and the second suture end 25. A structural frame 55 holds the components of the clamping mechanism (i.e., the first electrode 40, the second electrode 45, and the spring 50) in place. Importantly, the structural frame 55 is electrically non-conductive between the first electrode 40 and the second electrode 45. Electrical circuit 60 includes, at a minimum, a power supply 65 and a switch 70, with electrical circuit 60 connected to first electrode 40 and second electrode 45, as shown in FIG. 2A, such that closing switch 70 applies a voltage across first electrode 40 and second electrode 45 and allows current to flow through first suture end 20 and second suture end 25 at contact point 30. Preferably, power supply 60 includes a DC battery, although in other versions, power supply 60 can include an external AC power supply with an isolation transformer and rectifier, or a low or high frequency AC power supply.

[0043] In other versions of the invention, additional features may be added to device 10 to facilitate its use as a surgical instrument, such as tissue penetration and suture passing means, tensioning means, clamping means for securing suture ends 20, 25 to facilitate welding with the suture under tension, suture tail trimming means, weld area drying gas introduction means, an elongated and / or serpentine delivery shaft, and / or a handle for a manual user interface or electromechanical interface for connection to a surgical robot. These additional means and features are well known in the art and are described in detail in prior patents by the present inventor and others (e.g., U.S. Pat. No. 5,417,700).

[0044] An illustrative method and process for forming a weld in an electrically conductive thermoplastic suture 15 is shown in FIG. 2B. Closing switch 70 causes current to flow from first electrode 40, through first suture end 20, across contact point 30, through second suture end 25, and then to second electrode 45. The highest resistance in this circuit is at contact point 30, causing heat generation in this area and spreading into first suture end 20 and second suture end 25. The heat generation results in a localized molten region 75, which spreads into first suture end 20 and second suture end 25 as the heat increases. In one version, switch 70 is opened and the current is stopped before the melt spreads across the entire cross-section of the suture material. This differs from conventional resistance welding of metals, where the entire metal thickness is typically desired to participate in the weld, due to the anisotropic nature of drawn and extruded monofilament sutures.

[0045] To repeatedly and reliably achieve the optimal depth of fusion penetration into the suture ends 20, 25, several process control methods can be used. Many of these process control methods will reference circuitry and components (e.g., microprocessors and various sensors) not shown in the simplified diagrams shown in FIGS. 2A and 2B, but which may be assumed to be in place in a conventional manner familiar to those skilled in the art. In one such version, a simple timer is used to control the amount of time the welding circuit is switched on. In another version, the first and second electrodes 40, 45 are configured to move toward each other as the fusion spreads, displacing molten material, until the electrodes 40, 45 contact each other when the optimal amount of material has melted. The touching electrodes short together, shunting the current around the suture and halting heating. A current sensor can then be used to signal the microprocessor to interrupt the welding circuit. In another version, the displacement sensor may be replaced with a self-contacting electrode to signal the microprocessor to interrupt the circuit when the desired welding displacement occurs. Another version uses a temperature sensor to control the welding circuit through the microprocessor, where a preset peak temperature or thermal distribution is sensed. In yet another version, a combination of time, displacement, and temperature sensors is used, and the optimum welding parameters are determined by a microprocessor-based algorithm.

[0046] Tissue Fastening Device or Construct Formed by Welded Sutures Figure 3 shows a tissue fastening device or construct 100 having a length of electrically conductive thermoplastic material formed in situ into a continuous loop and joined by a partial-depth penetration weld. In this illustration, a region of virgin monofilament 105 can be seen, which has high tensile strength resulting from highly linearized molecular chains (represented conceptually by lines roughly parallel to the suture axis), surrounding a welded region 110 with amorphous molecular orientation (represented conceptually by random, disorganized lines). The tensile strength of the virgin monofilament is significantly stronger than that of the remelted region.

[0047] When tension is applied to the loop, the overlapping top and bottom loop ends load the weld area in shear, and because the area of ​​the weld area is larger than the cross section of the suture, stresses in this area are reduced insofar as there is virgin high strength suture material on either side of the weld area to distribute the load.

[0048] Molded Thermoplastic Tissue Fixation Device. Figures 4A and 4B show a clip 150 made from a molded, electrically conductive thermoplastic material that can be electrically welded in situ to, for example, occlude blood vessels, such as veins and arteries, for surgical hemostasis, or clamp tissue together. Figure 4A shows the clip 150 prior to deployment. The clip 150 includes a first end 155 having a recess 160 and an opposing second end 165 having a protruding feature 170. The protruding feature 170 on the second end 165 mates with the recess 160 on the first end 155 to create a high-resistance contact point for initiating a weld melt. Figure 4B shows the clip 150 welded in situ around a blood vessel 175. Electrodes (not shown) applied to the facing surfaces of the first end 155 and second end 165 on the clip 150 initiate a weld melt zone 180, joining the first end 155 and second end 165 together and causing the clip 150 to occlude the blood vessel 175.

[0049] 5A and 5B show another illustrative device 200 made from a molded conductive thermoplastic material that is electrically welded in situ to occlude a section of a hollow organ 205 (such as a stomach), allowing the organ to be surgically divided. Device 200 includes (i) a first strip 210 having an array of conductive thermoplastic needles 215 terminating in needle tips 220, and (ii) a second strip 225 having mating recesses (not shown) for receiving needle tips 220. In this version of the invention, an apparatus (not shown) delivers first strip 210 of conductive thermoplastic needles 215 through two layers of the organ (i.e., through two sidewalls of the hollow organ), and second strip 225 is welded to needle tips 220 of first strip 210 after needle tips 220 penetrate and emerge from the organ. By controlling the depth of fusion of the needles 215, the distance between the top portion (i.e., second strip 225) and the bottom portion (i.e., first strip 210) of the device 200 can be controlled, thereby controlling the degree of "squishing" applied to the organ and accommodating organs having varying thicknesses. In this manner, a welded surgical fastener, similar in function to a stitch or row of surgical staples, can be delivered in a continuous linear process.

[0050] Suturing Instrument Figure 6 shows a surgical suturing instrument 300 including a distal end 305 and a proximal end 310 connected by a shaft 315. The distal end 305 is an end effector and includes mechanical and electrical means for manipulating tissue and suture material to form a surgical stitch. The proximal end 310 contains actuation means for driving and operating the stitch-forming means at the distal end 305 through wires and linkages (not shown in Figure 6) that pass through the shaft 315. The shaft 315 has a length sufficient to reach anatomical structures within the interior of the body, with the proximal end 310 of the instrument remaining outside the body, allowing the distal end 305 to reach the target tissue at the surgical site and the shaft 315 to pass through intervening tissue and spaces, for example, by passing through an incision in a body wall, such as the abdominal wall. In one version (not shown), the proximal end 310 of the instrument 300 includes a handle adapted to be held by a human hand, and the actuation means on the proximal end 310 includes various buttons, triggers, levers, etc. for controlling the stitch-forming means at the distal end 305 and a battery for providing power for welding the suture. In another version (also not shown), the handle contains a motor, linear actuator, pneumatic or hydraulic cylinder, or other actuation means for driving the stitch-forming means, microprocessor-controlled circuitry for determining the stitch-forming and welding sequence, a trigger or button for initiating the stitch-forming process, and a battery for powering the actuator and circuitry. Still other versions have the handle and external power means, such as a power cord or pneumatic or hydraulic hose. In another version (shown), the proximal end 310 includes an electrical and / or mechanical interface 320 for connection to a surgical robot.

[0051] 7A shows one version of a distal end effector 305 for surgical suturing instrument 300 (or other surgical suturing instrument). Distal end effector 305 includes a slidable grasper 325 for grasping a piece of tissue and a means for threading and welding a loop of suture around the grasped tissue, as will be discussed in more detail below.

[0052] The slidable grasper 325 includes a passageway 330 for passing a length of conductive thermoplastic polymer monofilament suture 335 (having a distal end 337) therethrough, a hook feature 340 with a groove 345 opening into the hook feature 340, and a needle eye 350 aligned with the groove 345 of the hook feature 340. The slidable grasper 325 also includes a bore 352 for passing a needle 355 therethrough.

[0053] In use, and now looking at FIG. 7B, the hook feature 340 of the slidable grasper 325 is moved proximally (i.e., in the direction of arrow 357) to clamp the tissue (not shown) to be sutured between the first textured gripping surface 360 ​​and the second textured gripping surface 365.

[0054] 7C, needle 355 includes a groove 370 such that after needle 355 is advanced through tissue (not shown) sandwiched between gripping surfaces 360, 365, and after needle 355 is disposed within needle hole 350 of hook feature 340, groove 370 in needle 355 is aligned with groove 345 in hook feature 340, thereby forming a continuous circular path (i.e., by groove 345 of hook feature 340 and groove 370 in needle 355).

[0055] 7D , the suture 335 may be advanced through the continuous circular path formed by the groove 370 of the needle 355 and the groove 345 of the hook feature 340 until the distal end 337 of the suture 335 passes back over the portion of the suture 335 proximal to the distal end 337, thereby forming a loop of suture that passes through the tissue captured in the distal end effector 305, and the distal end 337 of the suture 335 comes into contact with the proximal portion of the suture 335 at the overlap region 375. The suture 335 may be advanced by motor-driven rollers in the shaft 315 and / or proximal end 310 of the instrument 300 that engage and push the suture 335 through the circular path, or by other drive means (not shown) known to those skilled in the art in the shaft 315 and / or proximal end 310 of the instrument 300.

[0056] After suture 335 has been advanced through the circular path described above to form a suture loop, articulating gripping mechanism 400 may be used to firmly grasp distal end 337 of suture 335 adjacent the proximal portion of suture 335 at overlap region 375, leaving the proximal portion of suture 335 free to slide axially for tensioning. To this end, and looking now at FIG. 7E , articulating gripping mechanism 400 includes first and second levers 405, 410, which pivot about pins 415 and 420, respectively. As the suture 335 is advanced through the groove 370 of the needle 355 and the groove 345 of the hook feature 340, the levers 405, 410 are held apart, aligning with the groove 370 in the needle 355 and the circular groove 345 of the hook feature 340 to create a gap, thereby allowing the distal end 337 of the suture 335 to pass through the gap to form a suture loop. After the distal end 337 of the suture 335 is in place in the overlap region 375, the levers 405, 410 close over the distal end 337 of the suture 335, grasping the distal end 337 and holding it firmly in place within the overlap region 375. With the exception of a first electrode 425 disposed where the levers 405, 410 grip the distal end 337 of the suture 335, the levers 405, 410 are made of a non-conductive material. The electrode 425 is in electrical contact only with the distal end 337 of the suture 335 .

[0057] After the distal end 337 of the suture 335 is clamped by the levers 405, 410 within the overlap region 375, the needle 355 is retracted and the suture advancement means that advanced the suture 335 through the circular path is reversed, retracting the loop of the suture 335 and tightening the loop of the suture 335 around the tissue grasped by the slidable grasper 325 (FIG. 7F).

[0058] Once the suture loop is tightened around tissue (not shown), the second electrode 430 is advanced to contact the portion of the suture that overlaps the distal end 337 of the suture 335 in the overlap region 375 (i.e., portion 440 in FIG. 7G). An electrical potential is applied across the first electrode 425 and the second electrode 430, causing a current to flow across the overlapping suture region 375, thereby causing heating, melting, and the formation of a weld in the manner described above in connection with FIG. 2A.

[0059] After welding the distal end 337 of the suture 335 to the proximal portion of the suture in the overlapping suture region 375, the knife blade 500 is advanced to cut the suture supply proximal to the weld, separating the welded loop from the instrument 300 (FIG. 7H). The hook feature 340 of the slidable grasper 325 is then moved distally to reopen the slidable grasper 325, thereby removing the clamped tissue. 7A. The first lever 405 and second lever 410 are also separated to release the welded loop stitch 445 that encircles the tissue (FIG. 7I). The actuator at the proximal end 310 of the instrument 300 then returns the distal end effector 305 to the position of FIG. 7A, and the instrument 300 is ready to form another stitch.

[0060] It should be understood that a wide range of additional devices and systems are possible that utilize the disclosed materials, apparatus, and methods and are included within the scope of the present disclosure.

[0061] End Effector for Use in Robotic Surgery. FIG. 8A shows a version of the present invention incorporated into a highly articulated end effector 801 for robotic surgery. This embodiment includes a four-degree-of-freedom (DoF) slave robot end effector remotely controlled by a surgeon residing at a master robot control console. The primary degrees of freedom include an instrument shaft 802 that rolls about axis R, a mid-section "knuckle" 803 that articulates in pitch about axis P, and first (804) and second (805) independently rotating tool elements (each rotating about yaw axis Y) disposed opposite one another. Other robotic end effectors use articulated segments or other means to achieve 4 or 5 DoF motion, and the present invention also applies to these devices. The end effectors described thus far in this paragraph are known in the art and are commonly used in robotic surgery. We will now describe novel aspects unique to the present invention.

[0062] Figure 8B shows an embodiment of the invention that forms suture stitches in the same manner as the invention described in Figures 7A-7I, but differs through the addition of a highly articulated end effector (e.g., the end effector of Figure 8A). In one embodiment, a first articulating opposing tool element 804 is a semicircular-shaped rigid body with an inwardly facing groove 810 that terminates in a needle hole 811 at its distal end. A second tool element 805 is a semicircular-shaped needle with an inwardly facing suture groove 812 and a sharp tissue-piercing point 813 at its distal end. The distal portion of needle 805 (i.e., second tool element 805) has a radius 814 to align with needle-receiving hole 811 in tool element 804. When the first and second tool elements 804 and 805 are closed opposite each other (as shown in FIG. 8A), the inwardly facing grooves 810 and 812 form a continuous groove through which the suture can be advanced.

[0063] 8C shows a partial cross-sectional view of an embodiment of the invention, schematically displaying a means for forming a suture stitch with the end effector. A flexible suture delivery tube 820 aligns with grooves 810 and 812 in the opposing tool elements 804 and 805 when the tool elements 804 and 805 are closed against each other. A distal end 821 of the suture delivery tube 820 is fixed relative to the first tool element 804 (in other embodiments, the mechanism may be reversed and the delivery tube 820 may be fixed to the second tool element 805). The flexibility of the suture delivery tube 820 allows it to maintain its alignment with the first tool element 804 throughout the full range of motion of the articulating end effector. The flexible suture delivery tube 820 serves the same purpose as the suture channel 202 illustrated in FIG. 7A, with the difference that it is flexible and allows for articulation of the end effector.

[0064] Figures 8D, 8E, and 8F show detailed views of suture grippers 825 and 826. Suture grippers 825 and 826 serve multiple functions during the suture formation process. In one embodiment, they are positioned on angled guide surfaces (not shown in Figures 8D, 8E, and 8F, but of a type well known in the art of gripping mechanisms) provided on the end effector such that grippers 825 and 826 separate as they move distally and come together as they move proximally. Their movement is controlled by a flexible gripper actuation linkage 827, which is flexible enough to actuate the grippers throughout the entire range of motion of the end effector. Grippers 825 and 826 move to three distinct positions: a feed position (Figure 8D), a clamping / welding position (Figure 8E), and a release / cutting position (Figure 8F). In the feed position (FIG. 8D), the grippers are partially separated to allow the suture to pass between them; in the clamping / welding position (FIG. 8E), steps 828 in the gripper surfaces come together to clamp and hold the distal end of the suture strand (i.e., the overlapping portion of the suture strand) for loop tensioning and welding; and in the release / cut position (FIG. 8F), the grippers are separated wide enough to release the welded loop of suture, and a sharp cutter surface 829 slides distally and cuts the welded suture loop free from the suture supply emerging from the feed tube 820.

[0065] 8C also shows a welding electrode 830 that is actuated distally and proximally by a flexible electrode linkage 831, which is flexible enough to control the movement of the welding electrode throughout the entire range of motion of the end effector. In one embodiment, suture grippers 825 and 826 are electrically insulated except for the distal surfaces of the grippers that contact the distal sides of the overlapping conductive suture segments held in the clamped position. Electrode 830 is electrically insulated except for a portion of its distal surface that may be brought into contact with the proximal sides of the overlapping conductive suture segments held in the clamped position. In one embodiment, either or both of flexible actuation linkage 827 (of grippers 825 and 826) and 831 (of electrode 830) are insulated and conductive and are arranged to deliver electrical energy to either the grippers or the electrode, or both. In other embodiments, separate, flexible, insulated wires deliver electrical energy to either or both of the grippers 825 and 826 and / or the electrode 830. In embodiments in which only one element (i.e., the grippers 825 and 826 or the electrode 830) has insulated conductors, the other element (i.e., the electrode 830 or the grippers 825 and 826) may be connected to ground through the instrument shaft and to the component. An electrical potential is applied between the uninsulated portions of the gripper surface and the electrode, causing current to flow through the overlapping conductive suture segments, thereby causing localized melting at the interface between the suture segments and resulting in a welded connection between the suture segments. A welded stitch is formed when the overlapping conductive suture segments are at either end of a continuous suture loop.

[0066] 9A-9E illustrate an embodiment of the present invention within the body as it may be viewed by a surgeon at the robotic control console.

[0067] 9A shows an opening 900 in tissue 901 that a surgeon wishes to close with a stitch. The surgeon's hand and wrist movements in the master robot on the control console are replicated by instrument end effectors 801 in the body. The surgeon's thumb and index finger movements are replicated by tool element 804 and needle 805. The surgeon positions tool element 804 and needle 805 across the tissue opening to be stitched.

[0068] 9B shows tool element 804 and needle 805 closing in opposition in response to the surgeon bringing their thumb and index finger together. Needle 805 penetrates through both sides of the tissue opening, completing a continuous circular groove (i.e., joined circular grooves 812 and 810) from needle 805 to tool element 804. When the surgeon is satisfied with the stitch location established by needle placement, the surgeon initiates the stitching process by pressing a foot switch, by voice-activated command, or by other available means for initiating an action. In some embodiments, the stitching process is a fully automated sequence. In other embodiments, some steps in the sequence are initiated automatically and other steps are initiated by the surgeon. The first step in this sequence is activation of a suture advancement mechanism connected to flexible suture delivery tube 820, which advances a fixed length of conductive suture equal to the circumference of the continuous inwardly facing grooves (i.e., joined circular grooves 810 and 812) of tool element 804 and needle 805, plus additional material to form an overlap region for the suture loop. The next step in the sequence is activation of an actuation mechanism, which is connected to flexible gripper actuation linkage 827 and suture grippers 825 and 826, which moves the grippers from a feed position (FIG. 8D) to a clamping / welding position (FIG. 8E), thereby gripping the distal end of the advanced suture in the overlap region.

[0069] 9C shows the tool element 804 and needle 805 opened and released from the tissue, leaving the conductive suture 905 threaded on either side of the tissue opening. In one embodiment, this motion is controlled by the surgeon at the control console by the separation of the thumb and index finger. In another embodiment, the separation of the tool element 804 and needle 805 is initiated automatically by the robot as part of an automated suturing process.

[0070] FIG. 9D shows the suture loop being tensioned by reversal of the suture advancement mechanism. In one embodiment, tensioning is initiated automatically, and the suture is pulled to a predetermined or programmed tension value. In another embodiment, the surgeon controls the tensioning process through a control means, such as a trigger, slide mechanism, foot switch, or similar means. In one embodiment, the control means includes tactile feedback, allowing the surgeon to feel the tension on the suture to achieve the desired tension in the stitch. In an embodiment in which separation of the tool element 804 and needle 805 is performed automatically by a robot, the surgeon controls and feels the tension through tactile feedback by separation of their thumb and index finger, which are temporarily released from controlling the movement of the tool element 804 and needle 805. Once the desired or predetermined tension is achieved, the welding process is initiated by actuation of an actuator connected to a flexible electrode linkage 831. An electrode 830 is brought into contact with the proximal side of the overlap region of the conductive suture loop with a predetermined contact force. An electric current is then passed through the overlap region (i.e., by passing a current between electrode 830 and grippers 825 and 826), causing the interfaces between the suture segments in the overlap region to locally melt and fuse into a weld.

[0071] FIG. 9E shows the final step of the stitching sequence, in which the tensioned welded loop 906 is cut free from the suture supply exiting the suture delivery tube 820 and released from the end effector by actuation and movement of the suture grippers 825 and 826 from the clamping / welding position (FIG. 8E) to the cutting / release position (FIG. 8F).

[0072] 10A shows an embodiment with integrated tissue grasping and manipulation capabilities. This embodiment of the end effector has a first tool element 804, a needle 805, and a second, opposing, hollow tool element 1000. The hollow tool element 1000 includes an opening 1001 large enough for the needle 805 to rotate therethrough and a blunt or textured, non-tissue-piercing end 1002 that is directly opposite and aligned with a corresponding blunt or textured, non-tissue-piercing end 1003 on the tool element 804.

[0073] 10B through 10e show an embodiment of an end effector with tissue grasping and manipulation capabilities (ie, the end effector of FIG. 10A) as it might be seen in-body by a surgeon at a robotic control console.

[0074] Figure 10B shows first and second opposing tool elements 804 and 1000 separated in preparation for grasping tissue. Needle 805 is outside hollow tool element 1000, with needle tip 813 (not shown in Figure 10B) protected within hollow opening 1001. Movement of the opposing tool elements is controlled by movement of the surgeon's thumb and index finger, with needle 804 moving with and maintaining its protected orientation by hollow tool element 1000 while the surgeon grasps and manipulates tissue as one would with surgical forceps.

[0075] 10C shows opposing tool elements 804 and 1000 gripping tissue at the location where the surgeon wants to place a stitch. The non-tissue-piercing ends of opposing tool elements 804 and 1000 pinch the tissue at the precise spot where needle 805 will penetrate, thereby facilitating easy entry and penetration by needle 805. When satisfied with the location, the surgeon begins the suturing process by pressing a foot switch, using a voice command, or using other means to initiate an automated sequence. The first step in the sequence is activation of an actuator that "fires" needle 805 through the tissue.

[0076] FIG. 10D shows that needle tip 813 has penetrated the tissue and is seated within needle hole 811 in tool element 804, establishing an uninterrupted suture groove (i.e., joined circular grooves 810 and 812) through the tissue (with tool element 804).

[0077] Figure 10E shows that the hollow tool element 1000 has been retracted from the tissue, either by action on the part of the surgeon or automatically as part of an automated stitching sequence, leaving the needle 805 in place (i.e., the needle 805 has been threaded through the tissue and is seated within the needle bore 811 in the tool element 804). The remainder of the stitching sequence is the same as that described in Figures 9B through 9E.

[0078] Modifications of the Preferred Embodiment It should be understood that many additional variations in the details, materials, steps, and arrangements of parts that have been described and illustrated herein to explain the nature of the invention may be made by those skilled in the art while still remaining within the principles and scope of the invention.

[0079] The following notes apply to the above embodiments: (Supplementary Note 1) A device for positioning within an animal's body, the device including a first portion and a second portion, the first portion and the second portion being positionable in contact with each other, the first portion and the second portion each comprising a biocompatible, electrically conductive thermoplastic material, wherein when the device is positioned within the animal's body and when an electric current flows from the first portion to the second portion, heat is generated by electrical resistance at the point of contact between the first portion and the second portion, melting regions of the first portion and the second portion; and when the electric current is subsequently stopped, the melted regions of the first portion and the second portion re-solidify, forming a weld between the first portion and the second portion. (Supplementary Note 2) The device of Supplementary Note 1, wherein the biocompatible, electrically conductive thermoplastic material comprises a composite of a biocompatible thermoplastic material and a biocompatible electrically conductive material. (Appendix 3) The device of Appendix 2, wherein the biocompatible thermoplastic material comprises a biocompatible thermoplastic polymer, the biocompatible conductive material comprises a biocompatible conductive additive, and further wherein the biocompatible thermoplastic material is formed by compounding the biocompatible thermoplastic polymer with the biocompatible conductive additive. (Appendix 4) The device of Appendix 3, wherein the biocompatible thermoplastic polymer and the biocompatible conductive additive are melt compounded, extruded, and drawn to form a monofilament suture. (Appendix 5) The device of Appendix 3, wherein the biocompatible thermoplastic polymer and the biocompatible conductive additive are melt compounded and molded to form a surgical fastener. (Appendix 6) The device of Appendix 2, wherein the biocompatible thermoplastic material and the biocompatible conductive material are co-extruded and drawn to form a suture. (Appendix 7) The device of Appendix 2, wherein the biocompatible conductive material is applied to the biocompatible thermoplastic material as a coating.(Appendix 8) The device of Appendix 7, wherein the biocompatible conductive material comprises a pattern of conductive ink applied to the biocompatible thermoplastic material as a coating. (Appendix 9) The device of Appendix 2, wherein the biocompatible thermoplastic material comprises at least one strand of a biocompatible thermoplastic polymer, the biocompatible conductive material comprises at least one strand of a biocompatible conductive material, and further wherein the biocompatible thermoplastic material is formed by intertwining the at least one strand of the biocompatible thermoplastic material and the at least one strand of the biocompatible conductive material. (Appendix 10) The device of Appendix 2, wherein the biocompatible thermoplastic material comprises a bioabsorbable thermoplastic polymer. (Appendix 11) The device of Appendix 10, wherein the bioabsorbable thermoplastic polymer comprises at least one from the group consisting of polylactic acid (PLA), polyglycolide (PGA), polydioxanone (PDS), and thermoplastic linear polyesters, such as those sold under the trademark TephaFLEX™. (Appendix 12) The device of Appendix 2, wherein the biocompatible thermoplastic material comprises a non-absorbable thermoplastic polymer. (Appendix 13) The device of Appendix 12, wherein the non-absorbable thermoplastic polymer comprises at least one from the group consisting of nylon, polypropylene, and polycarbonate. (Appendix 14) The device of Appendix 2, wherein the biocompatible conductive material comprises at least one from the group consisting of carbon black, carbon fiber, iron oxide (Fe2O3), metal powder, and metal nanoparticles. (Appendix 15) The device of Appendix 2, wherein the biocompatible conductive material comprises an intrinsically conductive polymer (ICP). (Appendix 16) The device of Appendix 15, wherein the intrinsically conductive polymer (ICP) comprises at least one from the group consisting of polyacetylene, polyaniline, polythiophene, and polyphenylene vinylene. (Appendix 17) The device described in Appendix 2, wherein the biocompatible thermoplastic material and the biocompatible conductive material are arranged such that the biocompatible conductive thermoplastic material provides conductivity in a first direction and prohibits conductivity in a different second direction.(Appendix 18) The device of Appendix 1, wherein the biocompatible conductive thermoplastic material comprises a biocompatible conductive thermoplastic polymer. (Appendix 19) The device of Appendix 1, wherein the device is in the form of a suture. (Appendix 20) The device of Appendix 19, wherein the suture is in the form of a welded suture loop. (Appendix 21) The device of Appendix 1, wherein the device is in the form of a surgical fastener. (Appendix 22) The device of Appendix 21, wherein the surgical fastener is in the form of a clip having a first leg and a second leg, further wherein the first leg and the second leg are separated by a gap. (Appendix 23) The device of Appendix 22, wherein the first leg is welded to the second leg. 24. The device of claim 21, wherein the surgical fasteners are in the form of a first strip including at least one needle having a needle tip and a second strip including at least one recess for receiving the needle tip of the at least one needle. 25. The device of claim 24, wherein the tip of the at least one needle of the first strip is welded into the at least one recess of the second strip.(Supplementary Note 26) An apparatus for forming a weld between a first portion of a biocompatible conductive thermoplastic material and a second portion of a biocompatible conductive thermoplastic material, the apparatus comprising: a first electrode; a second electrode; and a structure for holding the first and second electrodes facing each other with a space between the first and second electrodes to receive the first and second portions in contact with each other, the structure being non-conductive. an electrical circuit including a power supply and a switch, the switch being arranged such that closing the switch applies an electrical potential across the first and second electrodes, the first and second portions being positioned within an animal's body and placed in contact with one another between the first and second electrodes, when the switch is subsequently closed, heat is generated by electrical resistance at the point of contact to melt a region of the first and second portions, and when the switch is subsequently opened, the melted regions of the first and second portions re-solidify and a weld is formed at the point of contact. (Appendix 28) The device of Appendices 26, wherein the first and second portions are in the form of a continuous length of suture, and further comprising a needle and suture advancer for passing the suture through tissue so that the first and second portions are disposed adjacent to one another. (Appendix 29) The device of Appendices 28, further comprising a suture tensioner for tensioning the suture passed through tissue. (Appendix 30) The device of Appendices 26, wherein the device is in the form of an end effector for a surgical robot. (Appendix 31) The apparatus of Appendix 30, wherein the end effector has at least four degrees of freedom (DOF). (Appendix 32) A method for forming a weld between two pieces of biocompatible conductive thermoplastic material in an animal body, the method comprising: positioning first and second pieces of biocompatible conductive thermoplastic material in the animal body between a first electrode and a second electrode, such that the first piece is in contact with the first electrode, the second piece is in contact with the second electrode, and the first and second pieces of biocompatible conductive thermoplastic material are in contact with each other; applying a selected amount of current across the first and second electrodes, such that a selected amount of heat is generated by electrical resistance at the point of contact between the first and second pieces, causing a specific desired amount of melting of the first and second pieces; and terminating the current across the first and second electrodes, such that the melted regions of the first and second pieces re-solidify and a weld is formed at the point of contact.(Supplementary Note 33) An end effector for a suturing device, the end effector comprising: a first arm having a tissue engaging surface; and a second arm having a tissue engaging surface, at least one of the first and second arms (i) configured for movement toward the other of the first and second arms to clamp tissue between the tissue engaging surface of the first arm and the tissue engaging surface of the second arm, and (ii) configured for movement away from the other of the first and second arms to release tissue clamped between the tissue engaging surface of the first arm and the tissue engaging surface of the second arm, the second arm having an opening therein, and the end effector an end effector configured to pass through the opening in the second arm as the needle moves toward the tissue engaging surface of the first arm, and to pass through the opening in the second arm as the needle moves away from the tissue engaging surface of the first arm. (Appendix 34) The end effector of Appendix 33, wherein at least one of the first and second arms is configured for pivotal movement, and further wherein the needle is configured for pivotal movement.(Appendix 35) The end effector of Appendix 33, wherein the needle includes a passage for slidably receiving a suture, the first arm includes an opening for receiving the penetrating tip of the needle, and the first arm includes a passage for slidably receiving a suture threaded from the opening in the needle to the first arm.

Claims

1. 1. A device for positioning within a body of an animal, said device comprising: a length of suture including a first portion, a second portion, and a loop portion connecting the first portion and the second portion, the first portion and the second portion being positionable in line contact with each other, each of the first portion and the second portion comprising a biocompatible, electrically conductive thermoplastic material; The device: in response to an electric current applied to the device while the first and second portions are positioned in line contact with one another while the device is positioned within the body of the animal, the electric current is conducted from the first portion to the second portion, and heat is generated by electrical resistance at the line contact between the first and second portions, the generated heat being sufficient to cause localized melting of partial cross-sectional areas of each of the first and second portions adjacent the line contact; after cessation of application of the current, the melted partial cross-sectional areas of the first and second portions re-solidify to form a weld at the line contact between the first and second portions, with the loop portion of the suture extending from the weld. It is configured as follows: device.

2. 10. The device of claim 1, wherein the biocompatible conductive thermoplastic material comprises a composite of a biocompatible thermoplastic material and a biocompatible conductive material having a higher conductivity than the biocompatible thermoplastic material.

3. 3. The device of claim 2, wherein the biocompatible thermoplastic material comprises a biocompatible thermoplastic polymer, the biocompatible conductive material comprises a biocompatible conductive additive, and further wherein the biocompatible conductive thermoplastic material is formed by combining the biocompatible thermoplastic polymer with the biocompatible conductive additive.

4. 4. The device of claim 3, wherein the suture is of monofilament construction, and the biocompatible thermoplastic polymer and the biocompatible conductive additive are melt compounded, extruded, and drawn to form the monofilament construction.

5. The device of claim 2 , wherein the biocompatible thermoplastic material and the biocompatible conductive material are co-extruded and stretched to form the suture.

6. The device of claim 2 , wherein the biocompatible conductive material is applied to the biocompatible thermoplastic material as a coating.

7. The device of claim 6 , wherein the biocompatible conductive material comprises a pattern of conductive ink applied as a coating to the biocompatible thermoplastic material.

8. 3. The device of claim 2, wherein the biocompatible thermoplastic material comprises at least one strand of a biocompatible thermoplastic polymer, the biocompatible electrically conductive material comprises at least one strand of a biocompatible electrically conductive material, and further wherein the biocompatible electrically conductive thermoplastic material is formed by intertwining the at least one strand of the biocompatible thermoplastic polymer and the at least one strand of the biocompatible electrically conductive material.

9. The device of claim 2 , wherein the biocompatible thermoplastic material comprises a bioabsorbable thermoplastic polymer.

10. 10. The device of claim 9, wherein the bioabsorbable thermoplastic polymer comprises at least one from the group consisting of polylactic acid (PLA), polyglycolide (PGA), polydioxanone (PDS), and thermoplastic linear polyester.

11. The device of claim 2 , wherein the biocompatible thermoplastic material comprises a non-absorbable thermoplastic polymer.

12. The device of claim 11 , wherein the non-absorbable thermoplastic polymer comprises at least one from the group consisting of nylon, polypropylene, and polycarbonate.

13. 3. The device of claim 2, wherein the biocompatible conductive material comprises at least one from the group consisting of carbon black, carbon fiber, iron oxide (Fe2O3), metal powder, and metal nanoparticles.

14. The device of claim 2 , wherein the biocompatible conductive material comprises an intrinsically conductive polymer (ICP).

15. 15. The device of claim 14, wherein the intrinsically conducting polymer (ICP) comprises at least one from the group consisting of polyacetylene, polyaniline, polythiophene, and polyphenylene vinylene.

16. 3. The device of claim 2, wherein the biocompatible thermoplastic material and the biocompatible conductive material are arranged such that the biocompatible conductive thermoplastic material provides electrical conductivity in a first direction and inhibits electrical conductivity in a different second direction.

17. The device described in claim 16, wherein the first direction is a transverse direction of the first and second portions of the length of suture, and the second direction is an axial direction of the first and second portions of the length of suture.

18. The device of claim 1 , wherein the biocompatible, electrically conductive thermoplastic material comprises a biocompatible, electrically conductive thermoplastic polymer.

19. 1. An apparatus for forming a weld between a first piece of biocompatible conductive thermoplastic material and a second piece of biocompatible conductive thermoplastic material, the apparatus comprising: a first electrode; a second electrode; and a structure for holding the first electrode and the second electrode facing each other with a space between them to receive the first and second portions in contact with each other, the first and second portions being lengths of suture that are each placed in line contact with each other, the structure being electrically non-conductive between the first and second electrodes; an electrical circuit including a power supply and a switch, the switch being positioned such that closure of the switch applies an electrical potential across the first electrode and the second electrode; The apparatus comprises: with the first and second portions positioned within an animal's body and in line contact with one another between the first electrode and the second electrode, in response to closing the switch, current is conducted from the first portion to the second portion such that heat is generated by electrical resistance at the line contact, the generated heat being sufficient to cause localized melting of partial cross-sectional areas of each of the first and second portions adjacent the line contact; After opening the switch, the melted partial cross-sectional area of ​​the first and second portions re-solidifies, forming a weld at the line contact and a loop of the suture extending from the weld. It is configured as follows: Device.

20. 20. The apparatus of claim 19, wherein the structure causes the first electrode and the second electrode to apply a compressive force to the first portion and the second portion.

21. 20. The device of claim 19, further comprising a needle and suture advancing mechanism for passing the suture through tissue such that the first portion and the second portion are disposed adjacent one another, the suture advancing mechanism configured to advance a fixed length of the suture through a path that includes the tissue.

22. 22. The apparatus of claim 21, further comprising a suture tensioner for tensioning the suture passed through tissue.

23. 20. The device of claim 19, wherein the device is in the form of an end effector for a surgical robot.

24. 24. The apparatus of claim 23, wherein the end effector has at least four degrees of freedom (DOF).

25. 20. An end effector for a suturing device, the end effector having the apparatus of claim 19, wherein the structure for holding the first electrode and the second electrode opposite each other comprises: a first arm having a tissue engaging surface; a second arm having a tissue engaging surface; at least one of the first arm and the second arm is configured (i) for movement toward the other of the first arm and the second arm to clamp tissue between the tissue engaging surface of the first arm and the tissue engaging surface of the second arm, and (ii) for movement away from the other of the first arm and the second arm to release tissue clamped between the tissue engaging surface of the first arm and the tissue engaging surface of the second arm; the second arm having an opening therein; The device comprises: a needle having a piercing tip, the needle (i) configured for movement toward the tissue engaging surface of the first arm to position the piercing tip of the needle adjacent the tissue engaging surface of the first arm to thereby pierce tissue clamped between the tissue engaging surface of the first arm and the tissue engaging surface of the second arm, and (ii) configured for movement away from the tissue engaging surface of the first arm to withdraw tissue clamped between the tissue engaging surface of the first arm and the tissue engaging surface of the second arm; the needle is configured to pass through the opening in the second arm as the needle moves toward the tissue engaging surface of the first arm and to pass through the opening in the second arm as the needle moves away from the tissue engaging surface of the first arm.

26. 26. The end effector of claim 25, wherein the at least one of the first arm and the second arm is configured for pivotal movement, and further wherein the needle is configured for pivotal movement.

27. 26. The end effector of claim 25, wherein the needle includes a passage for slidably receiving the suture, the first arm includes an opening for receiving the piercing tip of the needle, and the first arm includes a passage for slidably receiving the suture threaded from the passage in the needle to the first arm.

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