Reinforcement of the Central Rumen of the Controllable Machine

Abstract

The catheter sheath includes a central lumen extrusion having an inner layer defining a central lumen, a reinforcing structure surrounding the inner layer, and an outer layer surrounding the reinforcing structure; a plurality of rings disposed at a predetermined distance from one another on the outer layer of the central lumen extrusion in the distal section of the sheath; and an outer jacket surrounding the rings and the central lumen extrusion. The reinforcing structure includes one or more of a braid, a coil, and a laser-cut tube embedded between the inner and outer layers. The central lumen extrusion is adhesively bonded, laser-welded, or press-fit to the one or more rings. The reinforcing structure is offset toward the inner or outer surface, and the rings have chamfered, beveled, or rounded inner edges.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Provisional Application No. 63 / 112,931, filed on November 12, 2020, and U.S. Provisional Application No. 63 / 104,935, filed on October 23, 2020. The disclosures of the foregoing provisional applications are hereby incorporated by reference in their entirety for all purposes. The benefit of priority is claimed under 35 U.S.C. § 119(e).

[0002] This disclosure relates to medical devices. More specifically, this disclosure exemplifies embodiments of a reinforced central lumen extrusion for use in a tubular sheath of a steerable medical device, such as an endoscope or a catheter.

Background Art

[0003] Medical devices for minimally invasive surgery (MIS) procedures include catheters and endoscopic probes. Some of such medical devices are guided through a disposable or limited - use flexible tubular body, commonly referred to as a sleeve, sheath, or introducer sheath. Some of such introducer sheaths or sleeves are robot - controlled. Robot - controlled catheters and endoscopes have a catheter sheath with a steerable distal section and a non - steerable proximal section. The proximal section is connected to an actuator via an electromechanical connector, and the distal section is sized to be introduced into a patient's anatomical structure through a natural orifice or a small surgical incision. Similar catheters and endoscopes that can be inserted into a patient can be manually operated by a user without using automatic or robot control. In either case, one or more channels extend along the central lumen of the sheath to allow access for an imaging device (a small camera or an optical fiber probe) and / or an end effector (a biopsy tool or a treatment probe), and / or to pass a fluid (a contrast agent or a flushing solution).

[0004] To reduce exposure to fluids and minimize interaction with instruments passing through the lumen, the sheath generally includes an inner liner, and the inner surface of the inner liner is configured to meet specific requirements such as lubricity, hydrophobicity, flexibility, etc. The inner liner can be an extruded part in the form of a thin-walled tube with an inner diameter sized according to design requirements, made of a thermoplastic material such as Pebax®, nylon, polyimide, high-density polyethylene (HDPE), Plexar®, urethane, resin, or a combination thereof, or a fluoropolymer material. See, for example, U.S. Pat. Nos. 7,550,053, 7,553,387, 10,821,264, and U.S. Patent Application Publication No. 2009 / 0126862 (the disclosures of which are incorporated herein by reference).

[0005] In the case of a robotic control sheath, a plurality of drive wires or tendons extend along the wall of the sheath to enable the actuating portion to selectively operate (bend) the distal section of the sheath. Depending on the design, the distal section of the sheath has a plurality of bendable segments including rings made of a biocompatible polymer such as polytetrafluoroethylene (PTFE) or polyethylene (PE). Such rings are adhered to the outer surface of the inner liner. The drive wires or tendons (typically made of a metallic material such as a nickel-titanium (NiTi) alloy (nitinol), stainless steel, or other similar metals) are routed through through-holes (secondary lumens) provided in the walls of the rings. This type of steerable medical device (used for diagnosing and treating internal structures) is described in many patent documents such as U.S. Patent Application Publication No. 2016 / 0067450, International Publication WO / 2020 / 092097, U.S. Pat. Nos. 8,365,633, 9,144,370, and 10,687,694 (the disclosures of which are incorporated herein by reference in their entirety).

[0006] During use, when the sheath structure is bent at a tight curvature within the patient's tortuous anatomical structure, the gap between the rings increases at the outer radius of the bend and decreases at the inner radius of the bend. As a result, the inner liner stretches at the outer radius of the bend and undulates to form a bulge at the inner radius of the bend. When an instrument is passed through the central lumen of the sheath, the instrument may flex, the tip of the instrument may catch on the ring, and there is a risk that the instrument may protrude from the sheath in the space between the two rings. On the other hand, depending on the tool being inserted, the tip of the tool may catch on the "bulge" between the guide rings. Due to the above problems, there is a risk of damage to the catheter and the instrument or tool passing through it, and since the instrument cannot be passed through, the procedure using the instrument cannot be performed.

[0007] Therefore, there is a need to improve steerable medical devices (particularly robotically steerable catheters and endoscopes) with reduced overall diameter, which requires a more slender, flexible, and torsion-resistant central lumen. SUMMARY OF THE INVENTION

[0008] According to at least one embodiment of the present disclosure, an apparatus is provided that includes a catheter sheath having a reinforced central lumen extrusion. The catheter sheath extends longitudinally from a proximal end to a distal end along a sheath axis, and the catheter sheath includes: a central lumen extrusion having a plurality of layers, the plurality of layers including, in this order and substantially concentric with the sheath axis, an inner layer that defines a central lumen, a reinforcement structure that surrounds the inner layer, and an outer layer that surrounds the reinforcement structure; and a plurality of rings disposed on the outer layer of the central lumen extrusion, the plurality of rings being spaced apart from each other by a predetermined distance in a direction from the distal end toward the proximal end. The reinforcement structure of the central lumen extrusion includes one or more of a braided structure, a coil structure, and a laser-cut tube structure embedded between the inner layer and the outer layer, and the central lumen extrusion is adhered to one or more of the plurality of rings with an adhesive, or laser welded, or press fit.

[0009] According to one embodiment, a catheter sheath comprises: an elongate tubular body having a proximal end and a distal end, the tubular body defining a central lumen extending from end to end of the tubular body along a sheath axis. The tubular body includes an operable section formed from guide rings collectively arranged in the longitudinal direction of the tubular body, the guide rings being arranged at a predetermined distance from each other so as to form a gap therebetween. A central lumen extrusion section having an inner surface, a reinforcing structure, and an outer surface arranged substantially concentrically with the central lumen, in this order, between the tubular body and the central lumen; the reinforcing structure includes one or more of a braided structure embedded between the inner surface and the outer surface, a coil structure, and a laser-cut tube structure. The reinforcing structure is offset towards the inner surface or the outer surface.

[0010] According to one embodiment, an operable sheath comprises: an elongate tubular body having a proximal end and a distal end, the tubular body defining a central lumen extending from end to end of the tubular body. The tubular body includes an operable section formed from guide rings collectively arranged in the longitudinal direction of the tubular body, the guide rings being arranged at a predetermined distance from each other so as to form a gap between each pair of consecutive guide rings, the guide rings including wire conductors arranged substantially parallel to and equidistant from the central lumen; at least one control wire slidably disposed on each wire conductor, the distal end of the at least one control wire being attached to the operable section of the tubular body, the proximal end of the at least one control wire being configured to be mechanically connected to an actuator; and a central lumen extrusion section having an inner surface, a reinforcing structure, and an outer surface arranged substantially concentrically with the central lumen, in this order, between the tubular body and the central lumen. The reinforcing structure includes one or more of a braided structure embedded between the inner surface and the outer surface, a coil structure, and a laser-cut tube structure.

[0011] According to certain embodiments, the central lumen extrusion portion includes an inner layer and an outer layer that are concentric with each other, and one or more of a braided reinforcement structure, a coiled reinforcement structure, and a laser cut tube reinforcement structure are enclosed between the inner layer and the outer layer of the central lumen extrusion portion.

[0012] According to certain embodiments, both the inner layer and the outer layer are made of an elastic polymer material, and the inner layer includes a lubricity material not included in the outer layer or is coated with the lubricity material.

[0013] According to certain embodiments, the outer layer is made of a thermoplastic elastomer (TPE), and the inner layer is made of a thermoplastic polyurethane (TPU).

[0014] According to certain embodiments, the thickness of the inner layer is greater than the thickness of the outer layer. Alternatively, the thickness of the outer layer is greater than the thickness of the inner layer.

[0015] According to certain embodiments, the durometer of the inner layer is different from the durometer of the outer layer. For example, the durometer of the inner layer is higher than the durometer of the outer layer. Alternatively, the durometer of the inner layer is lower than the durometer of the outer layer.

[0016] According to certain embodiments, the coiled reinforcement structure included in the central lumen extrusion portion is a first coiled reinforcement structure composed of a metal wire and / or a polymer wire wound in a first direction with respect to the lumen axis, and the outer jacket includes a second coiled reinforcement structure composed of a metal wire and / or a polymer wire wound in a second direction with respect to the lumen axis, and the first direction is opposite to the second direction.

[0017] According to certain embodiments, the outer layer is made of an elastic polymer combined with a carbon black additive, and the inner layer is made of an elastic polymer combined with a lubricity additive or coated with a lubricity additive.

[0018] These and other objects, features, and advantages of the present disclosure will become apparent upon reading the following detailed description of the exemplary embodiments of the present disclosure in conjunction with the accompanying drawings and the provided claims.

Brief Description of the Drawings

[0019]

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[0020] In the following paragraphs, specific illustrative embodiments of a robotic medical system configured to use an operable medical device having a reinforced central lumen are described. Other embodiments may include alternatives, equivalents, and modifications. Additionally, the illustrative embodiments may include several features, and certain features may not be essential to some embodiments of the devices, systems, and methods described herein.

[0021] Throughout the figures, wherever possible and unless otherwise indicated, the same reference numerals and characters are used to denote like features, elements, components, or parts of the illustrated embodiments. Further, the present disclosure will be described in detail with reference to the accompanying figures, which are made in connection with the exemplary embodiments. It is intended that changes and modifications may be made to the illustrated exemplary embodiments without departing from the true scope of the present disclosure as defined by the appended claims. The drawings represent several possible configurations and approaches, but the drawings are not necessarily to scale, and certain features may be exaggerated, deleted, or partially cut away to more clearly illustrate and describe particular aspects of the present disclosure. The description set forth herein is not intended to be exhaustive or to limit or restrict the claims to the exact forms and configurations shown in the drawings and disclosed in the following detailed description.

[0022] As used herein, when a feature or element is referred to as being "on" another feature or element, such feature or element may be directly on top of the other feature or element or intervening features and / or elements may also be present. In contrast, when a feature or element is referred to as being "directly on" another feature or element, it is understood that no intervening features or elements are present. Also, of course, when a feature or element is referred to as being "connected to," "attached to," "coupled to," etc., another feature or element, it may be directly connected, attached, or coupled to the other feature or intervening features or elements may be present. In contrast, when a feature or element is referred to as being "directly connected to," "directly attached to," or "directly coupled to" another feature or element, it is understood that no intervening features or elements are present. Although described or illustrated with respect to one embodiment, features and elements so described or illustrated in one embodiment may be applicable to other embodiments. Also, as would be understood by one of ordinary skill in the art, a reference to a structure or feature being "adjacent" to another feature may include portions that overlap or are beneath the adjacent feature.

[0023] In this specification, ordinal terms such as first, second, third, etc. may be used to describe various elements, components, regions, parts, and / or portions. Of course, these elements, components, regions, parts, and / or portions are not limited by these designated terms. These designated terms are only used to distinguish one element, component, region, part, or portion from another region, part, or portion. Thus, a first element, component, region, part, or portion described hereinafter can be referred to as a second element, component, region, part, or portion for the sole purpose of distinction, but without limitation and without departing from its structural or functional meaning.

[0024] As used herein, the singular form is intended to include the plural form as well, unless the context clearly dictates otherwise. Further, of course, the terms "comprising," "including," and "having," when used in this specification and the claims, specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof not expressly recited. Further, in the present disclosure, when used particularly in the claims, the transitional phrase "consisting of" excludes any element, step, or component not specified in the claim. Further, it should be noted that some claims or some features of claims may be drafted to exclude any element, and such claims may use exclusive terms such as "alone," "only," etc. in relation to the recitation of claim elements, or may use "negative" limitations.

[0025] As used herein, the term "about" or "approximately" means within, for example, 10% of, within 5% of, or less than a given amount. In some embodiments, the term "about" may mean within measurement error or within manufacturing tolerances. In this regard, when being described or claimed, all numerical values may be read as if preceded by the word "about" or "approximately" even if not explicitly so stated. The phrases "about" or "approximately" may be used when describing magnitude and / or position to indicate that the recited value and / or position are within a reasonable expected range of the value and / or position. For example, a numerical value may include values that are ±0.1% of the recited value (or range of values), ±1% of the recited value (or range of values), ±2% of the recited value (or range of values), ±5% of the recited value (or range of values), ±10% of the recited value (or range of values), etc. Any numerical range, when recited herein, is intended to include the given boundaries and all sub-ranges subsumed therein. As used herein, the term "substantially" means allowing a deviation from the descriptor that does not adversely affect the intended purpose. For example, a deviation resulting from a limitation of a measurement, a difference within manufacturing tolerances, or a variation of less than 5% may be considered to be within substantially the same range. The specified descriptor may be an absolute value (e.g., substantially spherical, substantially vertical or parallel, substantially concentric, etc.) or a relative term (e.g., substantially similar, substantially the same, etc.).

[0026] The present disclosure generally relates to medical devices and exemplifies embodiments of a steerable catheter sheath for guiding a catheter and / or an optical probe applicable to an imaging device (e.g., an endoscope). The imaging device can also image using a small camera based on chip-on-tip (COT) technology, or can alternatively provide other forms of imaging such as spectral encoded endoscopy (SEE) imaging technology (see, e.g., U.S. Patent Nos. 10,288,868 and 10,261,223). In some embodiments, the imaging device may include an optical coherence tomography (OCT) device, a spectroscopic device, or a combination of such devices (e.g., a multimodality imaging probe).

[0027] Embodiments of manipulable instruments and their parts are described with respect to their position / orientation in three-dimensional space. As used herein, the term "position" refers to the position of an object or a part of an object in three-dimensional space (e.g., three degrees of translational freedom along Cartesian X, Y, Z coordinates), the term "orientation" refers to the rotational arrangement of an object or a part of an object (three degrees of rotation - e.g., roll, pitch, yaw), the term "pose" refers to the position of an object or a part of an object having at least one degree of translational freedom and the orientation of an object or a part of an object having at least one degree of rotational freedom (a total of up to six degrees of freedom), and the term "shape" refers to a series of poses, positions, and / or orientations measured along the elongate body of an object. As is known in the field of medical devices, the terms "proximal" and "distal" are used with respect to the operation of the ends of an instrument that extends from the user to the surgical or diagnostic site. In this regard, the term "proximal" refers to the part of the instrument closer to the user, and the term "distal" refers to the part of the instrument that is away from the user and close to the surgical or diagnostic site.

[0028] As used herein, the term "catheter" generally refers to a flexible, thin, tubular instrument made of a medical-grade material designed to be inserted through a narrow opening into a body cavity (e.g., a blood vessel) to perform a wide range of medical functions. A catheter may be an imaging device alone or may include tools used in therapeutic or diagnostic procedures. The more specific term "optical catheter" refers to a medical instrument that includes an elongate bundle of one or more flexible optical fibers having an optical imaging function disposed within a protective sheath made of a medical-grade material. A specific example of an optical catheter is an optical fiber catheter that includes a sheath, a coil, a protector, and an optical probe. In some applications, a catheter may include a "guide catheter" that functions in a similar manner to a sheath.

[0029] As used herein, the term "endoscope" refers to a rigid or flexible medical instrument that uses light guided by an optical probe to observe the interior of a body cavity or organ. A medical procedure in which an endoscope is inserted through a natural opening is called an endoscopy. Dedicated endoscopes are generally named according to the method of use or the location of use of the endoscope, such as bronchoscope (mouth), sigmoidoscope (rectum), cystoscope (bladder), nephroscope (kidney), bronchoscope (bronchus), pharyngoscope (pharynx), otoscope (ear), arthroscope (joint), laparoscope (abdomen), and gastrointestinal endoscope, etc.

[0030] With a steerable medical instrument, flexible access to a target lesion or other internal site (e.g., access with one or more curves) is provided while maintaining torsional rigidity and longitudinal rigidity, so that a physician can control an end effector located at the distal end (the end closest to the internal site) by operating the proximal end of the instrument (the end farthest from the internal site and closest to the physician). Some steerable medical instruments are robotic and use kinematic principles to actuate a bendable catheter sheath with drive wires that act in push and pull directions to bend a portion of the bendable body. However, as described above, to access deep lesions or other sites, it is necessary to minimize the outer diameter (OD) and maximize the inner diameter (ID) of the central lumen (or tool channel) of the catheter sheath. Thus, some medical steerable instruments may comprise a sheath with a minimum wall thickness, which can be improved by a reinforced central lumen as described in this disclosure.

[0031] First, the structural elements of the robotic medical system 1000 (including the bendable body 3 removably attached to the working part 7 via the connector assembly 5) will be described with reference to FIGS. 1A, 1B, and 2A-2C. The robotic medical system 1000 may include a continuum or multi-segment robot configured to form a continuously curved shape by actuating one or more curved sections of the bendable body 3. An example of a continuum robot is a snake-like endoscopic device as described in U.S. Patent No. 9,144,370, U.S. Patent Application Publication Nos. 2015 / 0088161, 2018 / 0243900, 2018 / 0311006, 2019 / 0015978, which are hereby incorporated by reference for all purposes.

[0032] In many medical devices that can be manipulated by such robot control, a polymer ring and a metal wire are arranged around a central lumen so as to form a flexible backbone for joint movement like that of a snake. Therefore, this type of steerable medical device is known as a snake-like robot or a continuum robot. The distal structure of the snake-like continuum robot is unique, and polymer rings are attached to the central lumen at predetermined intervals so as to form a skeletal structure with specific bending characteristics. The central lumen can be a single-lumen extrusion made of a low durometer material to reduce the force required to bend the skeletal structure. By making the single-lumen skeletal structure from a low durometer material, a relatively tight bending radius can be achieved. When the catheter sheath is bent into a curved shape, the gap between the rings becomes larger at the outer radius of the curved structure and smaller at the inner radius. Then, when an instrument is passed through the curved central lumen, due to the low durometer of the central lumen extrusion, the wall of the lumen may bend or contract, and there is a risk that the tip of the instrument will get caught on the ring and become immovable. Specifically, due to the low durometer of the central lumen extrusion, sufficient hoop strength cannot be obtained to resist the radial expansion and contraction (ovalization) of the central lumen. Therefore, there are cases where the central lumen cannot prevent the deflection of the instrument, and the instrument cannot be avoided from getting caught on the rings of the skeletal structure. In such a situation, there is a risk of damage to the catheter sheath and / or instrument inserted through the central lumen, which may interfere with the safety of the patient.

[0033] According to the present disclosure, one or more embodiments are directed to a central lumen extruded portion comprising an inner liner having an inner surface, a reinforcement structure, and an outer surface disposed substantially concentrically with the central lumen, in this order. The reinforcement structure includes one or more of a braided structure, a coil structure, and a laser cut tube structure embedded between the inner surface and the outer surface of the inner liner. In at least some embodiments, the reinforcement structure is offset towards the inner surface or the outer surface. According to the present disclosure, one or more embodiments are directed to a catheter sheath comprising a central lumen extruded portion and having a plurality of rings disposed longitudinally on the outer surface of the central lumen extruded portion at a predetermined distance from each other in a direction from the distal end towards the proximal end. At least some of the rings have a secondary lumen used as a conduit for a control wire or a support wire for actuating the distal end of the catheter sheath. The outer surface of the central lumen extruded portion and / or the inner surface of the ring are specially designed to achieve a tight curvature of the catheter sheath in an anatomical structure with a tortuous curvature exceeding 90 degrees.

[0034] <FIGS. 1A-1B: Robotic Medical System> Referring to FIGS. 1A and 1B, a robotic medical system will be described. FIG. 1A illustrates an exemplary embodiment of a medical system 1000 in a medical environment such as an operating room (OR). The medical system 1000 utilizes an actuatable instrument 11 (actuatable medical device) to perform a treatment on a patient 8 under the interactive commands of a user (e.g., a physician) 10. The medical system 1000 includes at least a navigation system 1, a control system 2, and an actuatable instrument 11. The actuatable instrument 11 includes an actuator portion 7 and an actuatable catheter sheath 100. The actuatable catheter sheath 100 includes a distal section 3 of a plurality of segments and a proximal section 4 of a single segment. The proximal section 4 is connected to the actuator portion 7 via a connector assembly 5. The actuator portion 7 is configured to be removably attached to a robotic platform (support platform) 9 as shown in detail in the insert view A of FIG. 1A.

[0035] The steerable instrument 11 can be configured for a number of medical and / or industrial applications. In medical applications, the steerable instrument 11 can be configured as a robotic endoscope using the principles of kinematic (robotic) navigation to guide a medical tool through a tortuous body cavity, as a steerable catheter, or as a surgical introducer sheath or sleeve. The robotic endoscope can be used in various diagnostic and intervention procedures such as colonoscopy, bronchoscopy, laparoscopy, video endoscopy, etc. In the case of a video endoscope, the steerable instrument 11 can be configured to include a small video camera (such as a CCD or CMOS camera) disposed at the distal portion of the bendable body 3, and an electrical wiring and illumination optical system (optical fiber) extending along the tool channel.

[0036] Figure 1B illustrates an exemplary embodiment of a medical system 1000 in a functional block diagram. The catheter sheath 100 has a proximal non-maneuverable section 4 and a distal maneuverable section 3 consisting of a plurality of curved segments (e.g., curved segments 14, 13, 12) arranged longitudinally along the longitudinal axis (Ax). At least one central lumen or tool channel extends along the length of the catheter sheath 100 and through a part of the connector assembly 5. In at least some embodiments, the maneuverable instrument 11 is controlled by a robotic control system 2 via an actuator 7. The actuator 7 is a hand-held controller (handle) connected to the proximal section 4 of the catheter sheath 100 by the connector assembly 5. The actuator 7 may include any force generator and mechanical elements used to generate and transmit sufficient actuation force to bend at least one curved segment of the maneuverable section 3. In that regard, the actuator 7 can include any device capable of generating and transmitting an actuation force, such as a mechanical force, hydraulic force, magnetic force, pneumatic pressure, etc. The support platform 9 may include, for example, a robotic arm and a linear stage 91, and the linear stage 91 functions to guide the maneuverable instrument 11 (control unit 7, connector assembly 5, and catheter sheath 100) in a moving direction (typically a linear motion) for the insertion and / or retraction of the catheter sheath 100 with respect to the patient 8.

[0037] The control system 2 generally includes electronic components such as a PID controller and / or a digital signal processor (DSP), along with appropriate software, firmware, and peripheral hardware that are generally known to those skilled in the art. The control system 2 may be part of the navigation system 1 (such as a computer or a system console), or it may be connected to the navigation system 1. The navigation system 1 includes essential software (computer-executable code, programs, and applications) executable by a central processing unit (CPU) 190 according to the interaction between the user and the system 1000 via a user interface 194 in order to control the steerable instrument 11. The operation of the CPU 190 may be realized by one or more processors of the computer loading and executing a program, or it may be realized by dedicated circuits (FPGA and ASIC). The user interface 194 may include, for example, a display device 192 (LCD, LED, or OLED display), and the display device 192 may include a graphical user interface (GUI) and / or a pointing device and a keyboard (not shown), or a touch screen.

[0038] The navigation system 1, the control system 2, and the actuator 7 are operatively connected to each other by a network connection or a cable bundle 199 and a data bus system 195. Among several functions, the navigation system 1 can provide the surgeon or other users with the GUI and other information displayed on the image display device 192, so that the user can interact with the steerable instrument 11 and remotely operate the steerable instrument 11.

[0039] The control system 2 is configured to control an actuating unit 7 that includes a plurality of actuating motors (or actuators) 70-1, 70-2, … 70-M. The number of actuators or motors 70 is determined according to the design of the actuating unit 7. It may include a single (one) actuator or motor capable of operating all drive wires independently, or a plurality of actuators or motors equal in number to the number of drive wires 115 such that each actuator or motor can operate each drive wire individually.

[0040] The control system 2 may include one or more sensors 74 or may be connected to one or more sensors 74. The sensor 74 may include a strain sensor and / or a position sensor configured to detect and / or measure a compressive force or a tensile force (actuating force) applied to the drive wire 115 to bend one or more of the segments 12, 13, 14. The sensor 74 can output a signal 75 corresponding to the amount of compressive force or tensile force (amount of strain) applied to the drive wire 115 at a given time. The signals 75 from the sensors 74 (strain sensors and / or position sensors) of each drive wire are sent to the control system 2 and each actuator is controlled individually. Thus, each drive wire can be actively controlled by a feedback loop to perform appropriate shaft guidance to navigate the steerable section 3 through a serpentine path within the lumen of the patient's anatomical structure.

[0041] <Figures 2A - 2B: Catheter Sheath Structure> Figures 2A and 2B illustrate further details of the catheter sheath 100 according to an embodiment of the present disclosure. Figure 2A is a 3D rendering of the catheter sheath 100 consisting of a non-maneuverable proximal section 4 and a maneuverable distal section 3, and Figure 2B is a perspective view. The maneuverable section 3 includes a plurality of curved segments including a proximal curved segment 14, an intermediate curved segment 13, and a distal curved segment 12. As shown in Figure 2B, each curved segment consists of two or more rings (a plurality of rings) arranged coaxially in the longitudinal direction to form a tubular structure. As shown in Figure 2A, the tubular structure also includes an outer jacket 80 and a central lumen extrusion 200. The central lumen extrusion 200 includes an inner liner 210 reinforced by a reinforcing structure 220. The inner liner 210 has an inner surface defining a central lumen or tool channel 150 and an outer surface on which a plurality of rings are disposed. The rings include a plurality of wire conduits (secondary lumens) through which the drive wire 115 and / or support wire 116 pass. The drive wire 115 is moved by an operating force to bend one or more segments of the maneuverable section. The support wire 116 is not actuated.

[0042] Figure 2B illustrates an example of the catheter sheath 100 without the central lumen extrusion section 200 and the outer jacket 80. As shown in Figure 2B, a plurality of drive wires 115 pass through the proximal section 4, pass through the wire conduit of the wire guiding ring 140 of the proximal bending segment 14, pass through the wire conduit of the wire guiding ring 130 of the intermediate bending segment 13, and pass through the wire conduit of the wire guiding ring 120 of the distal bending segment 12. Each bending segment of the steerable section is actuated by a set of opposing drive wires 115 that operate by a pulling or pushing force (actuating force) for bending each bending segment independently of one another. Different forces F1, F2 of different magnitudes can be applied longitudinally to the separate drive wires to bend the various bending segments in a desired direction. Also, a combined force of the forces F1, F2 can be applied to bend a given bending segment in an additional direction. For this purpose, a first set of the drive wires 115 can be fixed to the anchor ring 120A at the distal end of the distal segment 12, a second set of the drive wires 115 can be fixed to the anchor ring 130A of the intermediate bending segment 13, and a third set of the drive wires 115 can be fixed to the anchor ring 140A of the proximal bending segment 14.

[0043] According to one embodiment, three drive wires 115 can be used to operate each bending section. In that case, the distal end of the drive wire 115 of the first set of drive wires can be fixed to the anchor ring 120A, the second set of drive wires can be fixed to the anchor ring 130A, and the third set of drive wires can be fixed to the anchor ring 140A. In such an example, nine drive wires 115 will pass through the proximal section 4 of the steerable sheath. In each anchor member, it may be advantageous to arrange (fix) the drive wires 115 equidistantly around each anchor member at strategic positions in order to operate each bending segment independently in a desired direction. For example, each drive wire 115 can be fixed to the anchor member at equal intervals. For example, if each bending segment is actuated by three wires, the drive wires will be fixed at 120-degree intervals so that each bending segment can be actuated in a substantially arbitrary direction (at an arbitrary angle with respect to the lumen axis Ax).

[0044] As shown in FIGS. 2A and 2B, each bending segment 12, 13, 14 of the catheter sheath includes a plurality of ring-shaped wire guiding members (guide rings), while the proximal non-steerable section 4 is a single elongated tubular component. Here, the tubular proximal section 4 and the central lumen extrusion 200 may be made from a similar biocompatible polymer material, such as a polyether block amide copolymer (e.g., the Pebax® brand manufactured by Arkema) which is a well-known polymer used in the manufacture of catheter shafts. Other medical-grade thermoplastic polyurethanes (TPU) and thermoplastic elastomers (TPE) materials can also be used as the tube extrusion materials for medical catheters and endoscope devices that require precision and consistency. Furthermore, other generally known catheter tube materials such as PVC, HDPE, polyurethane, nylon, FEP, PFA, ETFE, PTFE (liner), PEEK, TPE, Grilamid® lubricious film, etc. can be used.

[0045] <FIGS. 2C - 2D: Ring Structure> The wire guiding members (each guide ring) have a plurality of wire conduits (or through holes) along the wall of the guide ring. The through holes function as conduits for guiding wires along the wall of the tubular shaft. Again, wire conduits may be formed on the outer surface of each guide ring. The number of wire conduits of each wire guiding member is determined according to the curved section where the wire guiding member is disposed. The distal curved segment 12 includes a plurality of wire guiding rings 120, the intermediate curved segment 13 includes a plurality of wire guiding rings 130, and the proximal curved segment 14 includes a plurality of wire guiding rings 140. The distal curved segment 12 is connected to the intermediate curved segment 13 by an anchor ring 130A, and the intermediate curved segment 13 is connected to the proximal curved segment 14 by an anchor ring 140A. The proximal section 4 is a non-maneuverable section but includes a plurality of wire conduits extending through the wall (or the outer surface of the wall). Here, it should be noted that the wire conduits are not limited to through holes or conduits within the wall. In some embodiments, the wire conduits may be formed on the outer surface or the inner surface of a separate ring. Further, at least some of the rings may be formed without through holes or conduits.

[0046] FIG. 2C shows an exemplary representation of an annular guide ring having a central opening or tool channel 150 and secondary lumens or wire conduits (151, 152, 153, 154, 155, 156, 157, 158, 159, etc.) formed in the wall of the ring surrounding the tool channel 150. The outer surface and the inner surface of each guide ring are shown as circular for simplicity of illustration, but the actual implementation is not limited thereto. The outer surface and the inner surface of each guide ring structure may have a substantially symmetric closed polygonal shape such as a hexagon or an octagon.

[0047] FIG. 2C shows one wire induction ring 120, one wire induction ring 130, and one wire induction ring 140. The wire induction ring 120 includes three wire induction conductors (151, 154, 157), the wire induction ring 130 includes six wire induction conductors (152-153, 155-156, 158-159), and the wire induction ring 140 includes nine wire induction conductors (151, 152, 153, 154, 155, 156, 157, 158, 159). In this embodiment, nine drive wires 115 can be disposed through the tubular wall of the proximal section 4. Next, the drive wires continue through the wire conductors of the proximal curved segment 14 and are fixed to the anchor members for each curved segment. The anchor rings 120A, 130A, 140A have substantially the same structure as the corresponding wire induction rings 120, 130, 140, respectively. All wire induction members and anchor members include a central opening or tool channel 150 and have a predetermined number of through holes (wire induction conductors or secondary lumens) disposed around the tool channel 150 substantially parallel to and equidistant from the instrument axis Ax.

[0048] The number of through-holes in each ring or wire guiding member is determined according to the curved segment to which each ring belongs. However, in at least some embodiments, a ring having no through-holes may be included. For example, FIG. 2D illustrates a first ring 120 and a second ring 130 having different structures or functions. The first ring 120 has a tool channel 150 but no through-holes. Instead, the first ring 120 has an inclined slot 121 on the outer surface of the ring. The second ring 130 includes a tool channel 150, a plurality of through-holes 151 (secondary lumens) surrounding the tool channel 150, and also includes an open slot 131 on the outer surface of the ring. The inclined slot 121 of the first ring 120 or the open slot 131 of the second ring 130 can be used to dispose either an electronic component (e.g., an EM sensor) or a radiation-impermeable material (radiation-impermeable marker). The EM sensor or the radiation-impermeable marker can be used as a reference, for example, during an image-guided procedure. The axis Ax of each wire guiding ring (120, 130, 140) or guide ring is disposed substantially coaxially with the sheath axis Ax. The term "coaxial" in geometry technically means that two or more three-dimensional linear forms share a common axis. However, in the steerable sheath illustrated in FIG. 2B and other drawings disclosed herein, "coaxial" means that two or more components (e.g., an inner liner, a ring, and an outer jacket) share substantially the same axis. In some cases, some components may not be exactly coaxial but may be paraxial (i.e., having axes parallel to each other). However, for paraxial components with a small distance between the axes, it can be considered that the axes of such components are virtually coaxial.

[0049] Referring to FIGS. 2A - 2D, it will be appreciated that not all of the through - holes are used for the drive wire 110. At least some of such through - holes are used for passing electrical cables, and there are empty through - holes as well as those for passing support wires that are not drive wires. That is, according to at least one embodiment, the through - holes in each guide ring may have several uses. For example, there may be through - holes for accommodating control wires (drive wires), through - holes for accommodating support wires that do not transmit force, through - holes that remain empty, through - holes for passing optical fibers, through - holes for accommodating electrical cables, and through - holes for accommodating electronic components such as load cells and sensors. The rings of the manipulable section 3 may be made of a thermoplastic polymer with a similar biologic rigidity as that used for the central lumen extrusion section or the proximal section 4.

[0050] In at least some embodiments, the rings 120, 130, 140 are made of a transparent or translucent material that can facilitate adhesion to the central lumen extrusion 200. For example, the rings 120, 130, 140 are made of Pebax in its natural transparent color. When using a transparent material, the rings can be adhered to the central lumen extrusion by an adhesion process related to light energy transfer. Thus, even miniature rings can be adhered with stable adhesion quality as part of the manufacturing process. For example, a UV adhesive can be used to adhere the rings to the central lumen extrusion. In another design example, while the rings 120, 130, 140 are made of Pebax in its natural transparent color, the central lumen extrusion includes carbon black in its outer layer, and the black color is advantageous for more efficiently absorbing laser light. This specific combination of the ring and the central lumen extrusion enables the ring to be adhered to the central lumen extrusion by laser welding without affecting the inner surface of the central lumen. By laser welding, the ring and the central lumen extrusion are consistently and firmly adhered. To minimize unwanted heating from the adhesion portion to other parts, it is preferable that only the outer layer of the central lumen extrusion contains carbon black. Other examples of biocompatible medical grade translucent materials are described in U.S. Patent Application Publication No. 20160220735, which is incorporated herein by reference for all purposes.

[0051] Referring again to FIGS. 1A and 1B, the handle or connector assembly 5 provides an electromechanical interface between the proximal section 4 and the actuator within the actuator section 7. For example, the connector assembly 5 can provide a mechanical connection, an electrical connection, and / or an optical connection for interfacing the steerable instrument 11 with the control system 2 and the navigation system 1, as well as other data / digital connections. The handle or connector assembly 5 can also provide an access port 55 that can be used by a surgeon or other operator to insert an instrument or end effector through the tool channel 150. For example, the access port 55 can be used for inserting small instruments such as small forceps, needles, electrocautery instruments, etc. Further, the connector assembly 5 can include one or more dials or control wheels 52 for manually controlling (bending or steering) at least one segment of the steerable section. In some embodiments, the bendable body 3 can include a plurality of tool channels 150, and at least one of such channels can be used for passing a liquid and / or gaseous fluid, and another channel can be used for passing a tool or an imaging device.

[0052] During operation, the navigation system 1 and the control system 2 are communicably coupled via a data bus 199 to transmit and receive data from each other. Further, the navigation system 1 is connected to external devices such as a computed tomography (CT) scanner, a fluoroscopic imaging device, and an image server (not shown in FIG. 1A) outside the medical system 1000, and communicates with the devices. Examples of the image server include, but are not limited to, a DICOM (trademark) server connected to a PACS (Picture Archiving and Communication System) or a medical imaging system (which may include one or more of a CT scanner, a magnetic resonance imaging (MRI) scanner, a fluoroscopic device, etc.). The navigation system 1 processes data provided from the control system 2, data provided from images stored in the image server, or data provided from images from the CT scanner or the fluoroscopic imaging device. The navigation system 1 displays images and other medical information on the image display device 192 to assist the user 10 in performing medical procedures.

[0053] In a medical procedure in which the steerable instrument 11 is used, a medical image (for example, an image from a CT scanner) is provided to the navigation system 1 before the procedure. Using the navigation system 1, a clinical user creates an anatomical computer model from the image. In a particular embodiment of FIG. 1A, the anatomical structure can be the airway of the patient 8. From chest images received from a CT scanner or a PACS system, a clinical user can segment the airway for a clinical procedure such as a biopsy. After the navigation system 1 generates a map of the airway, the user can also create a plan to access a lesion to be biopsied using the navigation software system. The plan includes the target lesion and a trajectory (navigation path) through the airway for inserting the bendable body 3 (steerable sheath) of the steerable instrument 11.

[0054] The control system 2 includes firmware, a control circuit, and peripheral hardware for controlling the steerable instrument 11, the insertion portion 9, and the field generator 6 (e.g., an electromagnetic (EM) field generator). The control system 2 is communicatively coupled to the actuation unit 7, the insertion portion 9, the EM field generator 6, and a man-machine interface (e.g., a game pad controller not shown in FIGS. 1A - 1B). Thus, the control system 2 cooperates with the navigation system 1 to control the overall functions of the steerable instrument 11 and the insertion portion 9.

[0055] The steerable instrument 11 includes a bendable body 3, a handle or connector assembly 5, and an actuation unit 7. The actuation unit 7 is configured to bend one or more of the proximal bending segment 14, the intermediate bending segment 13, and the distal segment 12 according to commands from the control system 2 via the connector assembly 5 and based on a navigation plan provided by the navigation system 1.

[0056] According to one embodiment, when either inserting or retracting the steerable instrument 11, the control system 2 controls the linear stage 91 of the insertion portion 9 to move the bendable body 3 along the center line of the lumen (e.g., airway) in a desired trajectory, and then the bending segment can be actively controlled. This is similar to the known shaft guidance techniques used for controlling robotic-guided catheters or endoscopes, which aim to forcibly keep the flexible shaft of the sheath on the desired trajectory. In one example, when using the navigation system 1, the steerable instrument 11 is robotically controlled to advance the sheath through the lumen, while the sensor 74 measures differential forces, insertion depth, the angle of the user-controlled steerable segment, etc. to obtain trajectory information. The trajectory information is stored in the system's memory and continuously updated. After advancing the insertion or retraction distance slightly, the shape of the steerable body 3 is corrected by adjusting (actuating) one or more of the bending segments so that the new shape exactly matches the desired trajectory. This process is repeated until the target area is reached. The same process can also be applied when controlling the steerable instrument to withdraw the bendable body 3 from the patient. This process is similar to the navigation process described in, for example, US2007 / 0135803 (incorporated herein by reference for all purposes). Further details regarding the driving of the snake-shaped robot include operating methods as described in the applicant's previous patent application publications US2015 / 0088161, US2018 / 0243900, US2018 / 0311006, and US2019 / 0015978 (incorporated herein by reference for all purposes). To improve the navigation process, it is advantageous to reinforce the inner liner of the central lumen or tool channel 150.

[0057] <FIGS. 3 - 5: Central lumen extrusion with reinforcement structure> According to an exemplary embodiment, the steerable sheath of the bendable body 3 includes a central lumen extrusion with a reinforcement structure. The central lumen extrusion is an inner liner composed of one or more layers of polymer material, and is further strengthened by adding a reinforcement structure made of metal, metal alloy, polymer material, or a combination thereof to enhance its hoop strength, pushability, maneuverability, and torsional resistance. When the hoop strength is increased, the deflection of the inner liner is reduced, thereby preventing the instrument passing through the central lumen from being caught by the ring of the sheath. The reinforcement structure can be designed to increase the hoop strength without affecting the overall flexibility of the central lumen extrusion. The material used for the reinforcement structure can be any biocompatible metal or polymer. The reinforcement structure of the central lumen extrusion includes one or more of a braided structure combined with one or more layers of polymer (preferably an elastic polymer), a coil structure, and a laser cut tube (hypotube) structure. Thus, the central lumen structure can include one or more of a braided reinforced inner liner, a coil reinforced inner liner, and a laser cut tube reinforced inner liner.

[0058] FIG. 3 illustrates an exemplary embodiment of a central lumen extrusion 200 reinforced by a braided reinforcement structure 320. The central lumen extrusion 200 of FIG. 3 shows an inner liner 210 with a braided reinforcement structure 320 and a plurality of guide rings 120 collectively arranged (adhered) on the outer layer of the inner liner 210 to form one or more curved segments. Each guide ring 120 includes a plurality of wire guide conduits (wire conduits or secondary lumens). In FIG. 3, each guide ring 120 is illustrated as including a first wire guide conduit 151 and a second wire guide conduit 157 (see FIG. 2C). Two consecutive guide rings 120 are arranged at a distance D1 from each other so as to form a gap therebetween. The gap distance D1 is approximately equal to or smaller than the length L1 of each guide ring 120. Here, the length L1 and the gap distance D are measured in the longitudinal direction (i.e., parallel to the longitudinal axis Ax).

[0059] According to one or more embodiments, the ratio of the guide ring length L1 to the gap distance D may be adapted to achieve desired sheath characteristics such as hoop strength and bending flexibility. For example, the length L1 of each guide ring and the gap distance D between each pair of consecutive guide rings are in the range of 0.5 mm to 1.5 mm, or in the range of 0.75 mm to 1 mm. The ratio (L1 / D) of the length of each guide ring to the gap distance between consecutive guide rings is in the range of 3 to 0.3, or in the range of 2 to 0.5, or in the range of 1.5 to 1. Further, the length L1 of each guide ring and the gap distance D between each pair of consecutive guide rings are 1 mm and 0.5 mm, or 0.75 mm and 0.75 mm, or 0.75 mm and 0.5 mm, respectively. These dimensions apply to all embodiments (unless otherwise stated).

[0060] In FIG. 3, the reinforcement structure 320 consists of braided strands (filaments or threads) of a metal and / or a hard polymer material. As used herein, the terms "braided" or "meshed" refer to a structure or pattern formed by weaving or braiding two or more strands or threads of a flexible material such as a soft wire. The strands of wire may have a circular (round) or square (flat) cross-section. The inner liner 210 is reinforced by the braided structure 320 so as to have sufficient thickness and hoop strength to bend easily while maintaining torsional resistance and preventing the instrument from catching on the guide ring 120.

[0061] In the braided reinforced central lumen extrusion forming section, various materials can be used to improve the characteristics of the tubular shaft according to the performance characteristics to be achieved (for example, torsional resistance, kinking characteristics, improvement of flexibility, improvement of hoop strength, etc.). According to at least one embodiment of the present disclosure, the reinforced central lumen extrusion forming section of the inner liner 200 has three elements: an inner layer, a braided structure, and an outer layer. By combining these elements, specific characteristics can be obtained with respect to hoop strength, flexibility, kink / torsion resistance. At the same time, these three elements need to be combined to meet the desired dimensions (for example, the wall thickness of the reinforcing liner) and manufacturing / assembly tolerances. In that regard, the overall outer diameter (OD) and inner diameter (ID) size of the steerable sheath can necessarily limit the number of polymer layers and the type / thickness of the reinforcing structure that can be used. For example, in order to form a braided structure, it is necessary to repeatedly cross the braided filaments (braided wires), so the overall thickness of the inner liner 200 is determined by adding at least twice the diameter of the braided wire to the thickness of the inner layer, and further adding the thickness of the outer layer. Therefore, the larger the diameter of the braided wire, the higher the rigidity and torsional resistance can be obtained, but the minimum wall thickness becomes larger, which may affect the flexibility. On the other hand, when flat wires are braided to form a reinforcing structure, the minimum wall thickness can be maintained and the flexibility can be increased to some extent, but large torsional resistance may not be obtained.

[0062] Another aspect to consider with respect to the braided reinforcement structure 320 is the pick count. The pick count is expressed as the number of penetrations per unit length (PPI) and represents the number of times the braided wire crosses per inch of shaft length. According to an exemplary embodiment, the braided wire used in the current prototype is a 304 stainless steel (304SS) flat wire having a cross-section of 0.0005×0.003 inches. The braiding pattern used is 130 PPI, that is, 130 cells (picks) are repeated per inch of braiding. The higher the pick count, the more flexible the braid will bend. A typical braiding pattern is on the order of 70 - 80 PPI. In the present disclosure, since the central lumen extrusion needs to be bendable with a relatively low force input, a much higher pick count was prototyped and good results were obtained. The braid density is determined by the size of the flat wire and the size (inner diameter and outer diameter) of the central lumen extrusion. When the catheter sheath has a central lumen extrusion with an ID of 6 - 10 French, the braid density will be in the range of approximately 50 PPI to approximately 200 PPI accordingly. Further, the pick rate can be varied along the length of the central lumen to increase the flexibility near the distal end of the central lumen extrusion and increase the axial stiffness towards the proximal end. For example, depending on the application, the number of penetrations of the braided reinforcement structure 320 can be 50 - 200, and this value can vary along the length of the inner liner 210 such that the flexibility of the section increases in the direction from the proximal end to the distal end.

[0063] Figure 4 illustrates an exemplary embodiment of the central lumen extrusion portion 200 strengthened by the coiled reinforcement structure 420. The central lumen extrusion portion 200 of Figure 4 shows an inner liner 210 with a coiled reinforcement structure 420 and a plurality of guide rings 120 collectively arranged to form one or more curved segments. The coiled reinforcement structure 420 is made from a coiled wire of a metallic material and / or a coiled rod of a polymeric material. The rod of the polymeric material can include a single strand of polymeric fibers wound in a specific pattern (e.g., wound with a varying pitch) and / or a spool twisted multi-fiber rod to obtain the desired properties of hoop strength and bending flexibility. The coiled reinforcement structure 420 can be manufactured using various wires, filaments, threads or strands having flat, rectangular, square and / or round cross-sections, and can be made from metal or polymer-based materials such as stainless steel, nitinol, glass fiber, carbon fiber, nylon, fluorocarbon, PEEK, PET, PEN, Kevlar®. The arrangement of the guide rings 120 is the same as that described with respect to Figure 3 and the remaining embodiments. According to one exemplary embodiment, the wire used for the coiled reinforcement structure 420 is a 304SS wire of 0.001”×0.003” (substantially flat wire), although circular or round wires of similar dimensions can also be used. The coiled reinforcement structure 420 can provide the required hoop strength and can be more flexible than a braided reinforcement structure, although the braided reinforcement structure can provide better torsional rigidity. Thus, in some embodiments, the catheter sheath 100 can have multiple types of reinforcement structures.

[0064] FIG. 5 illustrates an exemplary embodiment of a central lumen extruded portion 200 strengthened by a laser cut tube structure 520. The central lumen extruded portion 200 of FIG. 5 shows an inner liner 210 with a laser cut strengthening structure 520 and a plurality of guide rings 120 collectively arranged to form one or more curved segments. The laser cut strengthening structure 520 is made from a metal or polymer tube 521 laser cut to form slots 522. The arrangement of the guide rings 120 is the same as that described with respect to FIGS. 3 and 4. According to one exemplary embodiment, the tube 521 may be made from 304SS or Nitinol, or alternatively from a polymeric polyimide. In an embodiment, the tube 521 can be a conventional hypotube laser cut in a specific slot pattern to provide hoop strength and lateral flexibility. To provide the desired combination of hoop strength, flexibility during bending, and resistance to catheter torsion, a continuous and / or intermittent spiral cut pattern of the slot cuts 522 can be deployed. When the laser cut strengthening structure 520 has an intermittent laser cut pattern, the laser cut tube can enhance the resistance of the central lumen extruded portion to compression and elongation compared to coiled or braided strengthening structures. Thus, in the catheter sheath 100 of an operable continuum robot, at least a portion of the catheter sheath section can consist of a central lumen extruded portion 200 having multiple layers strengthened by an embedded laser cut tube, as shown in FIG. 5.

[0065] Of course, the catheter sheath 100 can have a combination of reinforcement structures arranged alternately along the length of the central lumen extrusion 200. The reinforcement structure is selected from the laser cut tube, coil and / or braided reinforcement structures described in the foregoing embodiments. In one embodiment, each curved segment can have a different reinforcement structure. For example, the proximal segment 140 may have a central lumen extrusion 200 reinforced by a laser cut tube reinforcement structure 520, the intermediate segment 130 may have a central lumen extrusion 200 reinforced by a coil-like reinforcement structure 320, and the distal segment 120 may have a central lumen extrusion 200 reinforced by a braided reinforcement structure 420. The reinforcement structure may be interchangeably adapted for each curved segment according to the desired application and the need for hoop strength and flexibility.

[0066] <Figures 6A-6D: Offset of the Central Lumen Reinforcement Structure> Figure 6A shows an exemplary embodiment of the central lumen extrusion 200. The central lumen extrusion 200 includes an inner layer 210a, a reinforcement structure 220, and an outer layer 210b, which are arranged equidistant from the lumen axis Ax and substantially concentric with the lumen axis Ax in this order. The inner layer 210a and the outer layer 210b constitute the inner liner 210 shown in FIGS. 3, 4, 5, 7, 8, 10, and 11A-11B.

[0067] The reinforced central lumen extrusion section 200 can be made from plastic by any known process such as injection molding, blow molding, extrusion molding, etc. For example, the processes described in the previously referenced U.S. Patent Nos. 7,550,053 and 7,553,387, and U.S. Publication No. 2009 / 0126862 can be used to fabricate any of the reinforced central lumen extrusion sections of the embodiments disclosed herein. The reinforced central lumen extrusion section can be made from a continuous process that forms the entire central lumen extrusion section in a single process that combines the reinforcing structure 220 and the inner / outer polymer layers (210a, 210b), but the central lumen extrusion section can also be made in discrete processes using two or more different extruded parts (e.g., a first part that is the outer layer 210b extruded in a first step and a second part that is the inner layer 210a extruded in a second step). Thereafter, a third step of sandwiching the reinforcing structure 220 between the inner layer 210a and the outer layer 210b will be carried out.

[0068] The process of fabricating the inner layer in discrete processes can provide a configuration that allows for combinations of durometers that can provide benefits to the resulting central lumen extrusion section. For example, the first part that is the outer layer 210b can have a different material and a different durometer than the second part that is the inner layer 210a. Further, the length of the inner layer 210a, and / or the length of the outer layer 210b, can be made from separate parts having different materials / durometers.

[0069] FIG. 6B shows a cross-sectional view of the reinforced central lumen extrusion 200 taken along cross-section B-B of FIG. 6A. As shown in FIG. 6B, the reinforcement structure 220 may be disposed midway (in the middle) of the wall thickness, between the inner layer 210a and the outer layer 210b. However, in order to obtain specific requirements such as improved hoop strength and flexibility, the durometers of the materials used for the inner layer 210a and the outer layer 210b may be alternated, adjusted, changed, mixed, doped, etc. For example, according to one embodiment, a material with a higher durometer can be used for the inner layer 210a than for the outer layer 210b, and vice versa. In other words, the central lumen extrusion includes two layers (an inner layer and an outer layer) and a reinforcement structure disposed between the two layers. The two layers are joined by any known process to fix a reinforcement structure (a braid, coil or layer of laser cut tubes) therebetween. The material of the inner layer is a low friction material or includes a low friction material, and an example of the inner layer material is ePTFE. The outer layer material may be a low durometer material or a high durometer material, and an example of the outer layer material is Pebax®. As an advantageous effect, such a combination of features can enhance the torsional rigidity of the catheter body while maintaining good flexibility and hoop strength of the inner tube to accommodate tight bending curvatures.

[0070] According to an exemplary embodiment, the central lumen extrusion 200 includes an inner layer 210a made of a high durometer elastomer, an outer layer 210b made of a low durometer elastomer, and a reinforcement structure 220 of a braid, coil or laser cut tube disposed between the inner and outer layers. In order to enhance lubricity and / or to increase resistance to damage from tools or instruments passing through the lumen, a higher durometer inner layer 210a can be produced. As an advantage, since the inner layer 210a of the central lumen extrusion is closer to the central axis Ax of the lumen or tool channel 150, the higher the durometer of the inner layer 210a, the smaller the bending strain experienced by the inner layer 210a. In this case, the reinforcement structure may be offset towards the inner surface. Thus, the resulting reinforced central lumen extrusion achieves a desirable improvement in loop strength and flexibility.

[0071] According to another embodiment, the central lumen extrusion portion 200 includes an inner layer 210a made of a low durometer elastomer, an outer layer 210b made of a high durometer elastomer, and a reinforcing structure 220 of braid, coil or laser cut tube disposed between the inner layer and the outer layer. As an advantage, since the outer layer 210b is adhered to the guiding ring 120, when the sheath is bent, the high durometer outer layer 210b improves the bending flexibility and sufficient hoop strength is obtained. Examples of durometer values include high durometers in the range of about 63 to 72 Shore D and low durometers in the range of about 25 to 35 Shore D.

[0072] Low durometer polymers tend to be sticky on the surface. Therefore, when using a low durometer material for the inner layer 210a, certain measures need to be taken. Specifically, due to the sticky surface, the frictional force generated while the instrument passes through the central lumen or the tool channel 150 may increase. If this frictional force becomes smaller, the deflection of the central lumen extrusion portion 200 becomes smaller, and even if the equipment of the instrument becomes larger, it can pass through without being caught by the guiding ring. Therefore, according to an exemplary embodiment of the present disclosure, the friction of the inner layer is reduced by selecting different materials that have the same rigidity but provide improved lubricity. For this purpose, in an alternative embodiment, a lubricity additive can be added only to the inner layer 210a of the central lumen extrusion portion to enhance lubricity for easy passage of the instrument. When the lubricity additive is added only to the inner layer (more specifically, the inner surface), it does not affect the adhesion between the outer layer of the reinforced lumen forming portion and the guiding ring. Therefore, according to one embodiment, the inner layer 210a of the central lumen extrusion portion 200 may be made of a material that is more lubricious than the outer layer 210b or may be coated with such a material. Examples of more lubricious materials include expanded PTFE (ePTFE) and liners or coatings of other similar fluoropolymers.

[0073] Further alternative embodiments of the present disclosure use lubricating additives incorporated into the resin or material of the inner layer 210a of the central lumen extrudate 200. In this and other embodiments, the reinforcement structure 220 may be one or more of a braided reinforcement structure 320, a coiled reinforcement structure 420, and a laser cut tube reinforcement structure 520. For example, the steerable section of the catheter sheath can have a first curved segment reinforced by a braided structure, a second curved segment reinforced by a coiled structure, and a third curved segment reinforced by a laser cut tube structure. Regardless of the reinforcement structure used, the lubricating additive incorporated into the resin or material of the inner layer 210a increases the lubricity of the reinforced central lumen extrudate. Further, during the procedure, the frictional force can be reduced by applying a lubricant to the instrument or flowing it through the central lumen extrudate. In at least some embodiments, the inner and outer layers can be extruded from the same resin such as Pebax®, but additives can be incorporated into the base resin of the inner layer to enhance lubricity. There are various commercially available additives, such as Propell®, (Foster), Mobilize® (Compounding Solutions), Pebaslix®, (Duke Empirical), etc.

[0074] Thus, the inner layer 210a provides a high degree of lubricity to the inner diameter of the central lumen extrudate 200, thereby facilitating the passage of diagnostic or therapeutic devices through the central lumen without snagging on the skeletal structure's guiding rings. The inner layer 210a made of a more lubricious material has a smooth and hard inner surface, promoting smooth tool handling.

[0075] To further enhance hoop strength and bending flexibility, the reinforcement structure 220 is offset with respect to the central lumen extrusion layer. FIGS. 6C and 6D show cross-sectional views of the reinforced central lumen extrusion portion 200, respectively, with the reinforcement structure 220 offset with respect to the inner and outer layers. Conventional reinforced extrusion shafts have their reinforcement structure in the central part of the wall (i.e., the central part between the inner and outer layers), and the durometer of the shaft may vary in the longitudinal direction of the sheath. In contrast, according to at least one embodiment of the present disclosure, the reinforcement structure 220 is offset towards the outer layer 210b as shown in FIG. 6C, or towards the inner layer 210a as shown in FIG. 6D.

[0076] The offset of the reinforcement structure can be selected according to the desired characteristics of the resulting reinforced central lumen extrusion portion. For example, according to the embodiment of FIG. 6C, the reinforcement structure 220 may be offset towards the outer layer 210b (i.e., the reinforcement structure 220 is closer to the OD than the ID) to reduce the risk of braiding or coil or tube being exposed to the tool channel 150. This means that the thickness of the inner layer is greater than the thickness of the outer layer. In this case, the lifespan when using multiple tools can be improved. On the other hand, according to the embodiment of FIG. 6D, the reinforcement structure 220 may be offset towards the inner layer 210a (i.e., the reinforcement structure 220 is closer to the ID than the OD) to provide more material for the thermal bonding between the skeleton structure's guiding ring and the outer layer and prevent obstacles to downstream processing. This means that the thickness of the outer layer is greater than the thickness of the inner layer in this case. This can improve the affinity with the downstream process of adhering the guiding ring and the inner tube in the reflow / laser welding process. Furthermore, by providing the reinforcement structure near the ID, the hoop strength of the central lumen is increased.

[0077] Also, as will be described in more detail later, both the central lumen extrusion portion (inner liner) and the outer jacket extrusion portion can be reinforced using a reinforcement structure.

[0078] In any of the above-described embodiments, regardless of whether the reinforcement structure is offset, when only the outer layer contains a radiation-absorbing additive such as carbon black, the central lumen extrusion molding portion can be further improved. Carbon black is a type of quasicrystalline carbon used in an extrusion process as a reinforcing filler for rubber products (especially tires). Also, carbon black is a radiation-absorbing material that strongly absorbs light with wavelengths from ultraviolet to infrared (from about 350 nm to about 1100 nm). Therefore, in the present disclosure, a thermoplastic elastomer mixed with carbon black is used to form the outer layer of the central lumen extrusion molding portion to enhance the affinity with a downstream process (which is the adhesion of the guide ring to the inner liner by laser welding or reflow). In one embodiment, the outer layer of the central lumen extrusion molding portion may be formed by extrusion molding of a polyurethane elastomer containing about 0.5 wt% to 10 wt% of carbon black, or containing about 2% to 5% of carbon black.

[0079] When producing the outer layer from a thermoplastic elastomer (TPE) mixed with carbon black, in the central lumen extrusion molding portion in any of the above embodiments, only the outer layer can become a dark (black) colored layer, so laser welding for contacting the guide ring to the inner liner can be used more safely. Since the TPE mixed with carbon black absorbs more laser energy than the TPE alone, such an advantageous effect can be obtained. Thus, since only the outer layer is dark (black), while preventing heat from reaching the inner layer, the heat from the laser welding can bond the guide ring to the reinforced central lumen extrusion molding portion. As a result, by laser welding, the guide ring is effectively and reliably adhered to the outer surface of the central lumen extrusion molding portion, and the effect that the inner surface of the lumen is kept smooth as a tool channel is obtained.

[0080] The use of a carbon black additive in the outer layer of the central lumen extrusion is for the purpose of coloring (obscuration), but is considered important to achieve an appropriate hoop strength. The reason for this is that in the assembly process, only the outer layer becomes black and absorbs laser energy more efficiently, so the outer layer is selectively heated at the location where the guide ring is adhered to the central lumen extrusion by welding. Since the inner layer is not heated, the risk of overheating and melting of the inner layer can be reduced, and the effect on the smoothness of the central lumen can be prevented.

[0081] <Figure 7: Central lumen extrusion with enhanced outer diameter> According to a further exemplary embodiment, the central lumen extrusion can be strengthened by adding a strengthening structure to the outer diameter (OD) or outer surface of the central lumen extrusion. FIG. 7 illustrates an exemplary embodiment of a strengthened central lumen extrusion 200. According to this embodiment, the central lumen extrusion 200 includes an inner liner 210 made of one or more layers of polymer, similar to the above-described embodiments. In this embodiment, the inner liner 210 is strengthened by a plurality of thin-walled rings (strengthening rings) 720 formed between the attached guide rings 120. The thin-walled rings 720 may be provided in addition to, or instead of, embedding a strengthening structure (braid, coil or laser cut tube) within the layer of the central lumen extrusion. The thin-walled rings 720 have a smaller diameter, a smaller length, and the guide rings. Further, the thin-walled rings 720 may be made of a material having a specific Poisson's ratio that specifically allows the central lumen extrusion to bend without changing its diameter dimension. The thin-walled rings 720 can be made of a rigid polymer material and can be manufactured according to known processes such as those disclosed, for example, in U.S. Patent No. 7,815,975, which is incorporated herein by reference. However, in order to ensure sufficient space for bending of the catheter sheath while increasing hoop strength, the length L2 of the thin-walled rings 720 needs to be adjusted to achieve the desired flexibility and torsional characteristics. In that regard, the length L2 is smaller than the length L1 of the guide rings 120 and smaller than the gap distance D between consecutive guide rings 120. In at least some embodiments, one or more thin-walled rings 720 made of a radiopaque material (e.g., platinum, gold, or a radiopaque polymer) can be used. This will enable identification of the central lumen and / or one or more curved segments in image-guided procedures. The thin-walled rings 720 may be ePTFE rings disposed in a "ring gap" to enhance inner liner strength and to prevent damage to the sheath by a tool passing through when the catheter sheath is bent.

[0082] <Figures 8A - 8C: Reinforced Central Lumen Extrusion with Grooved Outer Surface and / or Chamfered Edge Guide Ring> According to a further alternative embodiment, the central lumen extrusion can be strengthened by increasing the wall thickness of the inner liner and providing a reinforcement structure in which the guide ring is adhered to the outer surface of the extrusion. Figure 8A illustrates an exemplary embodiment of a reinforced central lumen extrusion 200. Figure 8B shows a detailed view of region B of Figure 8A, showing an example of a method of attaching a guide ring to the central lumen extrusion. Figure 8C shows an exemplary embodiment of a guide ring 120 having a chamfered or beveled or rounded inner edge 825.

[0083] In this embodiment, the central lumen extrusion 200 has an inner liner 210 composed of one or more layers of a polymeric material similar to the previous embodiments. The central lumen extrusion 200 is strengthened by slightly increasing the thickness or number of layers that make up the inner liner 210 and forming a reinforcement structure in which the ring 120 is attached to the outer layer of the central lumen extrusion. In one embodiment, the inner liner 210 is reinforced by one or more of braiding, coiling, or laser-cut tubing as in the previous embodiments, but the ring is modified to have a chamfered inner edge 825. In other embodiments, the inner liner 210 is modified to form a groove 830 (grooved portion) in which the ring 120 with the chamfered edge 825 is disposed.

[0084] More specifically, a plurality of grooves 830 are formed on the outer surface of the inner liner 210 to provide the desired properties of improved hoop strength and lateral flexibility. As shown in region B of Figure 8A (enlarged view of Figure 8B), the grooves 830 can be formed at specific locations where the guide ring 120 is adhered or press-fitted to the central lumen extrusion. As an alternative to forming the grooves 830 or chamfering the inner edge 825, at least the inner edge 825 of the guide ring 120 may be made of a material that is softer (has a lower durometer) than the material of the outer layer 210b of the inner liner 210.

[0085] In this embodiment, in order to increase the inner diameter (ID) while obtaining the same performance enhancement, the inner liner 210 may be designed to have a groove 830. The groove 830 can be formed by laser cutting, heat shrinking, or reflowing the outer surface of the inner liner 210 at a position where the central extrusion part contacts the inner diameter of the guide ring 120. In this way, the wall thickness t2 of the liner 210 becomes smaller (thinner) only up to the thickness t1 at the portion where the groove 830 is formed. That is, the wall thickness of the central lumen extrusion part 200 becomes thinner at the portion where the inner liner 210 contacts the guide ring 120. This is because the wall strength is added to the inner liner 210 by the guide ring 120, and the wall thickness becomes thicker at the portion where the central lumen extrusion part does not contact the guide ring 120. The inner diameter (ID) of the central lumen extrusion part is continuously uniform and smooth, or there is no significant dimensional change along its length. On the other hand, there is a significant change along the length in the outer diameter of the inner liner 210. Also, the liner "relief or groove" 830 may have a curved (rounded) or chamfered end face. Thereby, it is possible to relieve the concentration of strain at one point where the outer surface of the inner liner 210 contacts the surface of the guide ring 120. Further, as shown in FIG. 8C, the inner edge (the edge of its inner surface) of the ring 120 may be rounded or chamfered at an angle α of about 30 to 45 degrees. The chamfered inner edge 825 of the guide ring 120 and / or the rounded end face of the groove 830 on the outer surface of the inner liner 210 can enhance the hoop strength and lateral flexibility while enhancing the durability of the sheath during repeated bending / use. Advantageously, when the inner edge 825 of the guide ring 120 is chamfered, bent, or beveled, it becomes less likely for an instrument passing through the central lumen to be caught on the edge of the guide ring 120 when the catheter sheath is bent.

[0086] <FIGS. 9A - 9B: Variation in the gap distance between the reinforced central lumen extrusion part and the guide ring> According to at least one embodiment, the hoop strength and flexibility of the central lumen extrusion having a reinforcement structure are further improved by adjusting (decreasing or increasing) the gap distance (D) between one or more consecutive guide rings among the curved segments. According to an exemplary embodiment, the shorter the gap distance between consecutive guide rings, the greater the increase in the flexibility resistance of the central lumen extrusion, and vice versa. Thus, by reducing the gap distance between consecutive guide rings of at least one curved segment (particularly the distal end curved segment), the possibility of the instrument getting caught on the guide ring during the procedure can also be minimized. However, careful consideration is required to achieve the appropriate amount of bending (radius) of the steerable instrument.

[0087] Figures 9A and 9B illustrate exemplary embodiments of an enhanced central lumen extrusion section in which the gap distance between successive guide rings of the curved segment is different. In FIGS. 9A and 9B, the central lumen extrusion section is not shown for ease of illustration of a first guide ring 120-1 and a second guide ring 120-2 that are arranged successively along the lumen axis Ax. The drive wire 115 passes through the wire conduits of each of the guide rings 120-1 and 120-2. As described elsewhere in the present disclosure, the drive wire 115 is operated (bent) to actuate (bend) the tubular body of the catheter sheath 100 by a pushing and pulling motion such that the gap distance between successive guide rings 120 becomes smaller along the inner radius and larger at the outer radius. The catheter sheath of the embodiment of FIG. 9A includes those having a smaller gap distance between the guide rings 120-1, 120-2 than the embodiment of FIG. 9B. In this case, in the catheter sheath according to the arrangement of FIG. 9A, the length of the central lumen extrusion section between the two successive guide rings 120-1, 120-2 is shorter. When an instrument or tool (e.g., a biopsy tool or a camera) is inserted through the central lumen or tool channel 150 of the sheath of FIG. 9A, the shorter central lumen extrusion section of FIG. 9A reduces the deflection compared to the embodiment of FIG. 9B, so that the tool is not caught by the guide ring. By bringing the guide rings closer to each other, the central lumen extrusion section between the two guide rings effectively becomes stiffer. Therefore, a greater force is required to deflect the central lumen extrusion section and the sheath as much as the tool is caught by the guide ring. Therefore, when the guide rings are arranged with a smaller gap distance, the instrument or tool passing through the central lumen extrusion section is more likely to follow the bending of the central lumen than to catch on the edge of the ring and protrude from the sheath through the space between the guide rings. As can be understood from the above description, by reducing the gap distance between successive guide rings, it is possible to improve the navigation of the instrument through the catheter sheath and minimize damage to the sheath and / or the tool.

[0088] <Figures 10 and 11A - 11B: Reinforced Outer Jacket> According to a further embodiment, in order to increase the hoop strength of the steerable sheath, both the outer jacket and the inner liner can be strengthened. FIG. 10 illustrates an exemplary embodiment of a catheter sheath 100 having a reinforced central lumen extrusion 200 and an outer jacket 800. The catheter sheath 100 includes a central lumen extrusion 200, a plurality of rings 120, an outer jacket 800, and a plurality of drive wires 115 disposed substantially concentrically about a longitudinal axis Ax. The central lumen extrusion 200 defines a central lumen or tool channel 150 configured to pass medical tools and devices for treating a patient's anatomical structure. The plurality of guide rings 120 include a wire conduit 151 for passing the drive wires 115. The drive wires 115 receive an actuating force (a pushing or pulling force) for bending at least one curved segment of the steerable sheath 100. According to various embodiments of the present disclosure, the catheter sheath 100 can bend at a minimum radius R of about 5.0 mm or less by more than 90 degrees (up to 180 degrees or more).

[0089] FIG. 11A shows a cross-sectional view of the catheter sheath 100 as seen from a plane perpendicular to the lumen axis Ax. According to FIG. 11A, the central lumen extrusion 200 defines a central lumen or tool channel 150 surrounded by a tubular wall consisting of an inner layer 210a, a reinforcing structure 220, and an outer layer 210b. Guide rings 120 are adhered to the outer surface (outer layer 210b) of the extrusion 200. The guide rings 120 include a plurality of wire conduits 151 configured to pass at least one drive wire 115 through one or more wire conduits. Among the wire conduits 151, there are those that are not used and those that can be used to pass other types of wires. The outer jacket 800 surrounds the guide rings 120. In FIG. 11A, the reinforcing structure 220 of the central lumen extrusion 200 is offset toward the inner surface such that the inner layer 210a is thinner than the outer layer 210b.

[0090] FIG. 11B shows a cross-sectional view of a catheter sheath 100 similar to that shown in FIG. 11A. According to FIG. 11B, the outer jacket 800 is also reinforced by a reinforcement structure 820 similar to the reinforcement structure 220. According to at least one embodiment, the outer jacket 800 includes an inner layer 810a, a coiled wire reinforcement structure 820, and an outer layer 810b. In this case, the coil of the reinforced central lumen extrusion 200 (inner liner) may be wound in a direction opposite to the coil of the reinforced outer jacket 800. For example, as indicated by the opposing arrows, the coil of the reinforcement structure 220 is wound in the clockwise (CW) direction, and the coil of the reinforcement structure 820 is wound in the counterclockwise (CCW) direction. Further, similar to the central lumen extrusion 200, the outer jacket 800 can have a reinforcement structure 820 offset toward the inner or outer surface. In the example shown in FIG. 11B, the reinforcement structure 820 of the outer jacket is offset toward the outer surface to increase the resistance to an external pressing force. By winding and combining the coils of the central lumen extrusion and the outer jacket in opposite directions, the torsional rigidity can be improved while sufficiently maintaining the hoop strength and flexibility of the sheath.

[0091] <FIG. 12: Exemplary manufacturing process> FIG. 12 illustrates the overall manufacturing process of a catheter sheath according to an embodiment of the present disclosure. For example, the process of FIG. 12 represents possible steps for fabricating a steerable catheter sheath for a snake-like continuum robot as shown in FIG. 2A. The steps in FIG. 12 can be modified (added or reduced) according to the type of application for which the catheter sheath is fabricated. In an exemplary manufacturing process of the catheter sheath, first, a reinforced central lumen extrusion is formed, second, a plurality of rings are disposed on the central lumen extrusion, and third, an outer jacket is disposed on the plurality of rings. The rings can have through-holes or secondary lumens formed and arranged to surround the central lumen. The rings can be attached to the outer surface of the central lumen extrusion and / or the inner surface of the outer jacket by press-fitting, adhesion, welding, or other methods. To ensure that the catheter sheath meets the minimum requirements, the final step of the process is to perform a bending test. These steps can be carried out in any type of manufacturing process known to those skilled in the art of medical devices.

[0092] In one example, in step S1202, first, a thin inner layer 210a is placed on a mandrel (not shown). In step S1204, a reinforcement structure 220 is disposed on the inner layer 210a. As described elsewhere, the reinforcement structure can include one or more of a braided structure, a coil structure, and a laser cut tube structure, or a combination thereof. In step S1206, an outer layer 210b is disposed on the reinforcement structure 220. At this point, any known process is performed to bond the inner layer 210a, the reinforcement structure 220, and the outer layer 210b. Depending on the desired catheter structure, the inner layer 210a can be made thinner than the outer layer 210b such that the reinforcement structure 220 is offset toward the inner surface of the central lumen extrusion. Alternatively, the inner layer 210a can be made thicker than the outer layer 210b such that the reinforcement structure 220 is offset toward the outer surface of the central lumen extrusion. Further, the inner layer 210a can have a higher or lower durometer than the outer layer 210b, and vice versa. In step S1204, any of the reinforcement structures including a braided structure, a coil structure, a laser cut structure, or a combination thereof can be disposed along the length of the inner layer 210a. In step S1206, the inner layer 210a and the outer layer 210b and the reinforcement structure therebetween can be bonded by any known process including one or more of press fitting, welding (e.g., ultrasonic or laser), adhesion using an adhesive material, adhesion by a thermal process (e.g., reflow, curing by UV energy, thermal shrinkage of the outer layer on the reinforcement structure). Further, the bonding can be performed along the entire length of the central lumen extrusion, or alternatively, only at selected portions where the reinforcement structure is applied.

[0093] In some embodiments, the inner liner 210 may be a readily available commercially available reinforced tube. In such embodiments, the inner liner may be a braided reinforced polymer tube such as a net-like 40D Pebax tube. In this case, steps S1202 to S1206 may be options for adding a layer of the reinforcement structure only at specific positions of the central lumen extrusion section. Alternatively, when using a readily available reinforced inner liner, the process may start from step S1208.

[0094] In step S1208, a plurality of first rings 120, a plurality of second rings 130, and a plurality of third rings 140 (shown in FIG. 2B) are arranged on the outer layer 210b of the central lumen extrusion section. As shown in FIGS. 2C and 2D, the rings can have secondary lumens or through holes 151 to 159, but at least a part of the rings may not have through holes. Here, when arranging the rings on the central lumen extrusion section, the rings may be press-fitted onto the outer surface (outer layer 210b) of the inner liner 210. Optionally, in step S1208, the rings can be welded or adhered to the outer surface of the outer layer 210b, or attached by other methods. The attachment of the rings to the central lumen extrusion section may be carried out by any known process including one or more of press-fitting, welding (such as ultrasonic welding or laser welding), adhesion using an adhesive material, and adhesion by a thermal process (such as reflow, curing by UV energy, etc.). It is natural for those skilled in the art that laser welding can be regarded as a part of the adhesion by a thermal process. In some embodiments, special primers or adhesives specially designed to enhance the adhesion strength to polymer materials such as PTU and PTE can be used. An example of a primer material for promoting adhesion to such materials is Loctite (registered trademark) SF770 (known as Loctie 770) commercially available from Henkel. The elastomer layer or polymer layer of the catheter sheath, which is generally difficult to adhere with conventional adhesives, can be coated or covered with a more adherent epoxy resin or other materials.

[0095] In step S1210, one or more wires can be disposed along the wall of the ring in the through-holes of the ring. In some embodiments, the wires can be disposed along slots formed on the outer surface of the ring (e.g., slot 131 in FIG. 2D). In the catheter sheath of the snake-like continuum robot, the wires can include one or more of drive wires (control wires that actuate one or more of the bending segments), support wires (non-actuated wires) that function as tendons or backbones of the robot, or cable wires (electrical cables composed of one or more metal strands that transmit electrical signals). Further, using the through-holes or slots formed in the ring, elongated sensors such as electromagnetic (EM) sensors, optical fibers, radiation-opaque markers, and other similar components can be disposed.

[0096] In step S1212, an outer jacket 80 is disposed over the entire structure covering the plurality of rings 120, 130, 140 of the steerable distal section 3, the central lumen extrusion section 200, and the non-steerable proximal section 4. In this step, additional rings can be welded or adhered or otherwise attached to the inner surface of the outer jacket 80.

[0097] In step S1214, a bending test is performed to confirm that the newly formed catheter sheath meets the required requirements. For example, in step S1213, the bending test checks whether the catheter sheath can bend at least 90 degrees (90+ degrees) without jamming of tools or instruments. To that end, several tests can be performed, such as bending the sheath at various radii of curvature or passing tools or instruments through the central lumen multiple times, to evaluate whether the sheath can withstand such severe use.

[0098] By combining any or all of the previous embodiments, the performance of the catheter can be steadily improved.

[0099] The foregoing embodiments are directed to a single inventive concept of a steerable sheath having a reinforced central lumen with enhanced loop strength and increased flexibility. The steerable sheath of a snake-like continuum robot is configured to guide a medical instrument through a reinforced central lumen by manipulating (kinematically actuating) one or more curved sections of the sheath. According to various embodiments, the reinforced central lumen extrusion includes one or more of the following features and provides one or more of the following advantages.

[0100] Main features: A flexible catheter sheath including a central lumen extrusion, a guide ring, and an outer jacket. The guide ring is adhered to the central lumen extrusion at a predetermined distance from each other. The outer jacket is outside the guide ring. The central lumen extrusion is a tubular body including a braided or coiled or laser-cut tube structure in the wall of the tubular body.

[0101] Dependent feature 1: The central lumen extrusion has an inner layer from the inner surface to the braided or coiled or laser-cut structure and an outer layer from the braided or coiled or laser-cut structure to the outer surface. The inner layer is made of a material with higher lubricity than the material of the outer layer.

[0102] Dependent feature 2: The same as dependent feature 1, and the outer layer is made of a thermoplastic elastomer. Dependent feature 2a: The same as dependent feature 1, and the outer layer is made of a thermoplastic elastomer mixed with carbon black.

[0103] Dependent feature 3: The same as dependent feature 1, and the wall thickness of the inner layer is greater than the wall thickness of the outer layer.

[0104] Dependent feature 4: The same as dependent feature 1, and the wall thickness of the inner layer is smaller than the wall thickness of the outer layer.

[0105] Dependent feature 5: The same as dependent feature 1, and the hardness durometer of the inner layer is lower than the hardness durometer of the outer layer.

[0106] Dependent Feature 6: It is the same as Dependent Feature 1, and the hardness durometer of the inner layer is higher than that of the outer layer.

[0107] Dependent Feature 7: The central lumen extrusion part has a first coil structure on the wall of the tubular body, and the outer jacket has a second coil structure on the wall of the outer jacket. The coiling of the first coil and the second coil is achieved by winding a metal wire around the inner surface (inner liner) and applying a medical-grade thermoplastic elastomer on the wound wire. The winding directions of the first coil structure and the second coil structure are opposite to each other.

[0108] Dependent Feature 8: The central lumen extrusion part is a reinforced flexible tubular body having a plurality of layers between the inner surface and the outer surface. The plurality of layers include an inner layer from the inner surface to a braided or coiled or laser-cut structure, and an outer layer from the braided or coiled or laser-cut structure to the outer surface. The outer layer contains carbon black, and the inner layer does not contain carbon black.

[0109] Dependent Feature 9: A catheter sheath comprising a central lumen extrusion part according to any one of Features 1 - 8, further comprising a plurality of rings disposed on the outer surface of the central lumen extrusion part.

[0110] Dependent Feature 10: It is the same as Dependent Feature 9, the rings are made of a transparent / translucent material, and the rings are adhered to the outer surface of the central lumen extrusion part by one or more of press-fitting, welding (laser welding or ultrasonic welding), adhesion using an adhesive, and adhesion by a thermal process (e.g., reflow or UV curing).

[0111] Advantages of adding a reinforcement structure: By braided reinforcement, an improvement in torsional rigidity, an improvement in hoop strength, and manufacturing in a continuous length (low cost) are achieved. By coil reinforcement, a thin wall thickness of the reinforcement part and an improvement in hoop strength are achieved. By laser-cut tube reinforcement, an improvement in resistance to compression, an improvement in hoop strength, and an improvement in torsional rigidity are achieved.

[0112] Advantages of using multiple materials / durometers in the inner liner layer: From the braid / coil towards the ID side, the lubricity is higher than that of the OD-side material, making it easier for the tool to pass through the channel.

[0113] Differences in different materials / durometers between the inner liner and the outer jacket: From the braid / coil towards the OD side, by using a thermoplastic elastomer with arbitrarily added carbon black, it becomes possible to adhere the guide ring using a reflow / laser welding process. By using a low durometer material for the outer jacket, the flexibility during navigation (insertion and extraction) is improved.

[0114] In one embodiment, the reinforcement structure (braid, coil or laser cut tube) is offset towards the inside of the wall thickness: This enhances the affinity with downstream processes including the adhesion between the guide ring using either the reflow or laser welding process and the outer surface of the inner liner. Also, the offset of the reinforcement structure increases the hoop strength.

[0115] In one embodiment, the reinforcement structure (braid, coil or laser cut tube) is offset towards the outside of the wall thickness. This reduces the risk of the reinforcement structure being exposed to the tool channel and improves the lifespan of the device when the tool is used multiple times.

[0116] In one embodiment, the inner layer of the central lumen extrusion is made of a low durometer material and the outer layer is made of a high durometer material. This is advantageous for maintaining good bending flexibility.

[0117] In one embodiment, the inner layer of the central lumen extrusion is made of a high durometer material and the outer layer is made of a low durometer material, and optionally a lubricity coating or lubricity additive is added. This makes the inner surface slippery and increases rigidity, promoting smooth tool handling.

[0118] In one embodiment, coil reinforcement is added to both the inner liner and the outer jacket. This improves torsional rigidity, increases hoop strength, and allows the bending flexibility in the central lumen extrusion section to be maintained.

[0119] In one embodiment, only the outer layer of the inner liner contains a carbon black additive. This increases the affinity with downstream manufacturing processes (such as the adhesion between the guide ring by laser welding and the outer surface of the inner liner). Since the outer layer contains a carbon black additive, only the outer layer becomes black, can absorb laser light, and can be selectively heated. Since the inner layer of the inner liner is not heated by laser welding, it is possible to reduce the risk of the inner surface melting or the smoothness of the lumen changing.

[0120] Other advantages include improved lubricity, low insertion force, minimal increase in material cost, narrowing of the gap between guide rings, reduced likelihood of the instrument getting caught on the guide rings, strengthening of the OD of the inner liner by the annular structure formed in the central lumen extrusion section between the guide rings, and improvement of the hoop strength of the central lumen.

[0121] The inner edge of the guide ring is chamfered, beveled, or curved, and / or a groove is formed in the outer diameter of the central lumen extrusion section: The likelihood of the instrument getting caught on the ring during insertion is reduced.

[0122] <Figure 13: Experimental Results> Experiments were conducted to evaluate in various ways a method for fabricating an improved bendable body for a steerable medical instrument having the above characteristics. In particular, when the medical instrument is located inside the body, exposed to a tortuous environment, and needs to undergo one or more tight bends (e.g., a bend of 90 degrees or more at a relatively small radius), the test was carried out by simulating an environment where the bendable medical instrument can receive various tools into the tool channel without getting caught.

[0123] Experiments were conducted using the catheter sheath design shown in any of FIGS. 3, 4, or 5. A bendable body having a single central lumen extrusion with a tool channel having an ID of 0.089 inches and an OD of 0.099 inches was fabricated from Pebax®, and the average hardness durometer was 35 Shore D. In one embodiment, the central lumen extrusion has a PTFE channel, and the channel has an ideal smooth surface machined from a PTFE block similar to the previous catheter structure described by the applicant in WO / 2020 / 092097. However, in the present disclosure, the central lumen extrusion is reinforced by a braided reinforcement structure. In other embodiments, at least the inner surface (inner layer) of the central lumen extrusion is made of a permeable material such as expanded polytetrafluoroethylene (ePTFE). Since the inner layer is microporous, the lubricity of the inner surface can be enhanced by adding a highly lubricious material, thereby improving the passage of medical tools without getting caught on the ring. In some embodiments, the inner liner has a lubricity additive such that the inner surface is lubricated. Such additives include, but are not limited to, Moblize, Pebaslix, and Propell.

[0124] One embodiment is directed to a steerable catheter with a reduced ring pitch. Using a reinforced central lumen extrusion, a steerable catheter having a structure similar to that shown in FIGS. 2A, 9A, and 9B was constructed. In the catheter with a reduced ring pitch, the ring pitch is shortened (the ring pitch is reduced by as much as 30% compared to the catheter previously disclosed by the applicant).

[0125] The experimental catheter prototype according to the above-described embodiment was tested and compared with the previously disclosed "as is" snake-shaped catheter. In the snake-shaped catheter tested "as is", the ring was 1 mm wide and the gap was 1 mm. The new catheter with a reduced ring pitch was fabricated using 0.75 mm rings, and the gap distance between consecutive rings was 0.75 mm. In this embodiment, the catheter with 0.75 mm rings and 0.75 mm gaps is shortened from the 1 mm wide gap. From the results, a significant improvement in insertion performance was shown while maintaining the bending radius performance to a minimum.

[0126] Figure 13 shows a graph including the experimental results of the bending of the new catheter sheath prototype compared to the previously disclosed catheter sheath ("as is" structure). These experiments are based on a bending radius of 15 mm and a bending curvature of at least 90 degrees to about 180 degrees.

[0127] As can be understood from Figure 13, by adding a braided reinforcement structure to the inner layer (dashed line), reducing the ring pitch by about 30% (dotted line), and creating the inner surface (tool channel) from a permeable material (ePTFE) and adding a lubricity additive (such as Moblize, Pebaslix, Propell, etc.) to the inner layer, the force required for the insertion and removal of the catheter through a tortuous path can be reduced.

[0128] According to some experiments, by reducing the ring width and gap distance to a 1:1 ratio, significantly better results were obtained than by shortening the ring width or gap distance alone. Maintaining the ratio of the ring width to the gap distance at 1:1 is significantly superior from the perspective of the minimum bending radius. For example, if only the gap distance is reduced (e.g., maintaining a 1 mm ring width and reducing only the gap between rings to 0.5 mm, the resulting minimum bending radius is 10 mm, whereas for 0.75×0.75 it is 5 mm).

[0129] When reducing the adhesive / laser welding ring surface area as defined in U.S. Patent Application Publication No. 2021 / 0259790, previously filed by the applicant and incorporated herein by reference in its entirety. According to this prior art document, since the surface area is large and the surface is readily accessible, there is also an option to laser weld the ring to the outer cover (outer jacket) rather than the central lumen extrusion.

[0130] Regarding tool insertion performance, the performance of a catheter with a ring width of 1.0 mm and a gap distance between rings of 0.5 mm was optimal. However, regarding the bending radius, this catheter had the maximum bending angle. On the other hand, in a catheter with a ring width of 0.75 mm and a gap distance of 0.75 mm, although the tool insertion performance was low, the bending radius was significantly smaller, which was a preferred embodiment depending on the application. A catheter with a ring width of 0.75 mm and a gap distance of 0.5 mm also showed good results.

[0131] The braided inner tube may be, for example, a readily available braided reinforced polymer tube such as braided 40D Pebax®. This braided inner tube can be attached to the ring structure and the outer tube by any known method. For example, laser welding can be used. In some embodiments, the laser welding may be biased towards the proximal end and / or the distal end of the tool channel. In such regions, a thicker structure can be provided to improve the laser welding. The braided inner tube can be selected to maintain the flexibility of the snake-like robot. Additives (such as lubricants) can be added to the inner diameter, or both the inner and outer diameters. The braided inner tube can be made of different materials for the inner and outer sides of the braid. In one embodiment, the inner layer contains a lubricity additive and the outer layer does not.

[0132] The braided inner tube may be, for example, a readily available braided reinforced polymer tube such as braided 40D Pebax. This braided inner tube can be attached to the ring structure and the outer tube by any known method. For example, laser welding can be used. In some embodiments, the laser welding may be biased towards the proximal end and / or towards the distal end of the tool channel. In such regions, a thicker structure can be provided to improve the laser welding. The braided inner tube can be selected to retain the flexibility of the snake-shaped robot. Additives (such as lubricants) can be added to the inner diameter, or to both the inner and outer diameters. The braided inner tube can be made of different materials for the inner and outer sides of the braid. In one embodiment, the inner portion contains a lubricating additive and the outer portion does not.

[0133] Catheter with an inner tube having a low Poisson's ratio: In some embodiments, the inner tube or liner has a Poisson's ratio smaller than a defined amount. When the Poisson's ratio is smaller than this amount, wrinkles in the inner liner at a sharp bending radius are eliminated. Also, since there is almost no stress in the liner, there is no opposing force, making it easier to maintain the posture of the catheter.

[0134] Other embodiments and variations When referring to the description, specific details are set forth in order to enable a complete understanding of the disclosed examples. In other instances, well-known methods, procedures, components, and circuits are not described in detail so as not to unnecessarily lengthen the present disclosure. Unless otherwise defined herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The scope of the present invention is not limited by this specification, but rather is limited only by the plain meaning of the terms of the adopted claims.

[0135] When describing the exemplary embodiments shown in the drawings, specific technical terms are used for clarity. However, the disclosure of this patent specification is not intended to be limited to the specific technical terms thus selected, and of course, each of the specific elements includes all technical equivalents that function similarly.

[0136] Although the present disclosure has been described with reference to exemplary embodiments, it goes without saying that changes can be made without departing from the scope of the present invention, particularly with regard to details, especially matters concerning the shape, size, and arrangement of components or steps. Therefore, the following claims should be given the broadest reasonable interpretation so as to encompass all such changes as well as equivalent structures and functions.

Claims

1. A catheter sheath extending in the longitudinal direction from the proximal end to the distal end along the sheath axis, A non-manipulable section and a manipulable section arranged in order from the proximal end to the distal end, wherein the manipulable section is manipulable via at least one control wire, the non-manipulable section and the manipulable section; A central lumen extrusion section extending through both the non-manipulable section and the manipulable section, the central lumen extrusion section having a plurality of layers, the plurality of layers including an inner layer defining a central lumen, a reinforcing structure surrounding the inner layer, and an outer layer surrounding the reinforcing structure, substantially concentric with the sheath axis in this order, the central lumen extrusion section; A plurality of rings disposed on the outer layer of the central lumen extrusion section in the manipulable section, the plurality of rings being disposed at a predetermined distance from each other in the direction from the distal end to the proximal end of the manipulable section; Comprising; The reinforcing structure of the central lumen extrusion section includes one or more of a braided structure, a coil structure, and a laser-cut tube structure embedded between the inner layer and the outer layer; The central lumen extrusion section is adhered and / or press-fitted into one or more of the plurality of rings; Catheter sheath.

2. The reinforcing structure is offset toward the inner surface or the outer surface of the central lumen extrusion section such that the thickness of the inner layer is different from the thickness of the outer layer; The catheter sheath according to claim 1.

3. Each of the plurality of rings has an inner surface and an outer surface made of a thermoplastic polymer; The outer layer of the central lumen extrusion section is made of a thermoplastic polymer; Each of the plurality of rings is attached to the outer layer of the central lumen extrusion section by press-fitting, or adhesion using an adhesive, or adhesion using a heating process, in such a manner that the inner surface of each ring is fixedly attached to the outer layer of the central lumen extrusion section; The catheter sheath according to claim 1 or claim 2.

4. The braided structure includes braided polymer fibers and / or braided metal strands disposed between the inner layer and the outer layer; The coil structure includes coiled metal wires and / or coiled polymer filaments disposed between the inner layer and the outer layer; The laser cut tube structure includes a metal tube and / or a polymer-based tube having a slot cut pattern, and the laser cut tube structure is disposed between the inner layer and the outer layer. The catheter sheath according to any one of claims 1 to 3.

5. An outer jacket surrounding the plurality of rings and at least a part of the central lumen extrusion molding part. Further comprising Each of the plurality of rings has an inner circumference in contact with the outer layer of the central lumen extrusion molding part and an outer circumference surrounded by the outer jacket. The catheter sheath according to any one of claims 1, 2 or 4.

6. Each of the plurality of rings has an inner surface in contact with the outer layer of the central lumen extrusion molding part. Two or more of the plurality of rings have chamfered or beveled or rounded edges on their inner surfaces, and when the central lumen extrusion molding part is bent, the chamfered or beveled or rounded edges of the two or more rings minimize the pressure of the two or more rings on the outer layer of the central lumen extrusion molding part. The catheter sheath according to any one of claims 1, 2 or 4.

7. The outer layer of the central lumen extrusion molding part is made of a thermoplastic polymer combined with carbon black. The plurality of rings are made of a transparent or translucent polymer material. The catheter sheath according to any one of claims 1 to 6.

8. The inner layer of the central lumen extrusion molding part is made of an elastic polymer combined with a lubricity additive or an elastic polymer coated with a lubricity additive. The catheter sheath according to any one of claims 1 to 7.

9. Each of the plurality of rings has a length in the longitudinal direction. The length of each of the plurality of rings is equal to or shorter than the predetermined distance at which the plurality of rings are arranged. The catheter sheath according to claim 1.

10. The ratio of the length of each ring to the predetermined distance at which the plurality of rings are arranged is in the range of 3 to 0.3, or in the range of 2 to 0.5, or in the range of 1.5 to 1. The catheter sheath according to claim 9.

11. The length of each ring and the predetermined distance at which the plurality of rings are arranged are 1 mm and 0.5 mm, or 0.75 mm and 0.75 mm, or 0.75 mm and 0.5 mm, respectively. The catheter sheath according to claim 9.

12. The non-maneuverable section has a diameter substantially the same as the diameter of the plurality of rings. The catheter sheath according to any one of claims 1 to 11.

13. The outer jacket includes an inner layer, a reinforcing structure, and an outer layer arranged substantially concentrically with the sheath axis in this order. The reinforcing structure of the outer jacket is formed by a coiled metal wire and / or a coiled polymer wire. The coiled metal wire and / or coiled polymer wire of the central lumen extrusion part is wound in a direction opposite to the coiled metal wire and / or coiled polymer wire of the outer jacket. The catheter sheath according to claim 5.

14. The central lumen extrusion part includes a first polymer layer forming the inner layer and a second polymer layer forming the outer layer. The reinforcing structure is offset toward the outer layer of the central lumen extrusion part so that the thickness of the first polymer layer is greater than the thickness of the second polymer layer. The catheter sheath according to claim 1.

15. The central lumen extrusion part includes a first polymer layer forming the inner layer and a second polymer layer forming the outer layer. The reinforcing structure is offset toward the inner layer of the central lumen extrusion part so that the thickness of the first polymer layer is smaller than the thickness of the second polymer layer. The catheter sheath according to claim 1.

16. The central lumen extrusion part includes a first polymer layer forming the inner layer and a second polymer layer forming the outer layer. The outer jacket includes an inner layer, a reinforcing structure, and an outer layer arranged substantially concentrically with the sheath axis in this order. The reinforcing structure of the outer jacket is offset toward the inner surface or the outer surface of the outer jacket in such a manner that the thickness of the inner layer of the outer jacket is different from the thickness of the outer layer of the outer jacket. The catheter sheath according to claim 5.

17. The central lumen extrusion molding part includes a first layer made of thermoplastic polyurethane (TPU) that forms the inner layer and a second layer made of thermoplastic elastomer (TPE) that forms the outer layer. Only the second layer made of TPE contains a carbon black additive so that the outer surface of the central lumen extrusion molding part absorbs heat from laser welding at a larger rate than the inner surface, and the first layer does not contain a carbon black additive. The catheter sheath according to claim 1.

18. The plurality of rings includes guide rings, and each guide ring has a wire guiding conduit arranged substantially parallel to the sheath axis and equidistant from the sheath axis. At least one wire guiding conduit of each guide ring includes at least one control wire slidably arranged along the length of the central lumen extrusion molding part. The distal end of the at least one control wire is attached to an operable segment of the operable section, and the proximal end of the at least one control wire is configured to be mechanically connected to an actuating part. The catheter sheath according to claim 1.

19. One or more reinforcing rings arranged on the outer surface of the central lumen extrusion molding part in a gap between one or more pairs of the plurality of rings arranged at the predetermined distance. further comprising Each reinforcing ring has a length shorter than the predetermined distance. The diameter of each of the reinforcing rings is smaller than the diameter of each of the plurality of rings arranged at the predetermined distance. The catheter sheath according to claim 1.

20. The operable section includes a plurality of curved segments. The central lumen extrusion molding part corresponding to each curved segment is reinforced by a different reinforcing structure selected from the braided structure, the coil structure, and the laser cut tube structure embedded between the inner layer and the outer layer. The catheter sheath according to claim 1.

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