Variable Stiffness Multi-Lumen Tube

Abstract

The medical device includes a shaft. The shaft includes an integral tube defining a plurality of lumens. The integral tube includes at least one of PTFE and ePTFE. A density of at least one of the PTFE and ePTFE varies along a length of the integral tube.

Description

[Technical field]

[0001] The present disclosure relates generally to medical devices, systems, and associated methods having multi-lumen tubes of polytetrafluoroethylene (PTFE) and / or expanded polytetrafluoroethylene (ePTFE), where regions of the tube have different stiffness, density, and / or other properties. [Background technology]

[0002] Medical devices used in endoscopy and other procedures, such as catheters, endoscopes, sheaths, tubes, etc., require a set of properties to function as intended. For example, during procedures such as endoscopy, colonoscopy, and / or endoscopic retrograde cholangiopancreatography (ERCP), a technician may insert the medical device into a patient and navigate the medical device across tortuous anatomical structures to place the medical device at a target site deep within the body. Access to the target site may require bending of more proximal portions of the device as well as articulation or movement at the distal portion of the device to effectively navigate to the target site and orient the distal portion to the location. Thus, the medical device may require portions with various properties, such as different flexibility / stiffness. Summary of the Invention

[0003] The medical device may include a shaft. The shaft may include an integral tube defining a plurality of lumens, the integral tube including at least one of PTFE and ePTFE, and the density of at least one of the PTFE and ePTFE varies along the length of the integral tube. The density may vary within a cross section of the integral tube. In an alternative embodiment, the density of a radially inner portion of the integral tube may differ from the density of a radially outer portion of the integral tube. The integral tube may include an articulation joint. At least two regions spaced apart about the circumference of the articulation joint may have a lower density than other regions about the circumference. The at least two regions may be spaced apart about 180 degrees about the circumference. In an alternative embodiment, the integral tube includes an articulation joint, the integral tube further includes a proximal portion to the articulation joint, the articulation joint being less dense than the proximal portion. In some embodiments, the device may further include one of a braid or a coil surrounding an outermost surface of the integral tube. One of the braid or the coil may be heated to a temperature of at least 250°C. At least one of the pitch, material, and thickness of the wire in one of the braids or coils may vary along the length of one of the braids and coils. The integral tube may further comprise at least one mandrel extending through at least one of the multiple lumens. The at least one mandrel may be at a temperature of 250° C. or greater. In an alternative embodiment, the integral tube may further comprise a plurality of mandrels extending through one or more of the multiple lumens. A first mandrel of the multiple mandrels may be at a first temperature and a second mandrel of the multiple mandrels may be at a second temperature different from the first temperature. A density of a proximal portion of the integral tube may differ from a density of a distal portion of the integral tube. The medical device may be an endoscope, and the shaft may be coupled to a handle at a proximal end of the shaft, and the multiple lumens may include a working channel and a lumen for an articulation wire.

[0004] A method of manufacturing a tube may include stretching a heated one-piece starting tube of at least one of PTFE and ePTFE to obtain an intermediate tube having a density less than that of the one-piece starting tube, the starting tube defining a plurality of lumens, and linearly shrinking only a first portion of the length of the intermediate tube when the intermediate tube is heated to obtain a final tube, the first portion being denser than a second portion of the final tube. The method may further include inserting a mandrel through one of the plurality of lumens, heating the mandrel to 250° C. or higher, and removing the mandrel. Tension may be applied to at least one of the starting tube, the intermediate tube, and the final tube. The linear shrinkage may be controlled by applying a force in a longitudinal direction of the tube.

[0005] The method of forming or manufacturing a tube may further include inserting at least one mandrel through at least one of the lumens of a multi-lumen tube comprising at least one of PTFE and ePTFE, heating the mandrel to a temperature of at least 250°C to obtain a first portion having a higher density than a second portion of the tube, wherein the first portion and the second portion are within the same cross section of the tube, and removing the at least one mandrel.

[0006] It will be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not intended to limit the invention as claimed. As used herein, the terms "comprises," "comprising," or variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or device comprising a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such process, method, article, or device. The term "exemplary" is used in the sense of "example" rather than "ideal." The term "distal" refers to a direction away from the operator / toward the treatment site, and the term "proximal" refers to a direction toward the operator. "About" and similar terms (e.g., "substantially") include values ​​of + / - 10% of the stated value. [Brief description of the drawings]

[0007] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate examples of the present disclosure and together with the description, serve to explain the principles of the disclosure. [Figure 1] FIG. 1 illustrates an exemplary medical device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 illustrates an exemplary method of manufacturing a PTFE tube according to an embodiment of the present disclosure. [Diagram 3] 3A-B show a tube in a straight configuration (FIG. 3A) and a curved configuration (FIG. 3B) according to an embodiment of the present disclosure. [Figure 4] FIG. 4 illustrates an exemplary section of a multi-lumen tube with variable stiffness according to an embodiment of the present disclosure. [Figure 5A] FIG. 5A illustrates an exemplary method for manufacturing a tube with variable stiffness according to an embodiment of the present disclosure. [Figure 5B] FIG. 5B illustrates the resulting exemplary tube according to an embodiment of the present disclosure. [Figure 6A] FIG. 6A illustrates an alternative exemplary method for manufacturing a tube with variable stiffness according to an embodiment of the present disclosure. [Figure 6B]FIG. 6B illustrates the resulting exemplary tube according to an embodiment of the present disclosure. [Figure 7] 7A-E show exemplary cross sections of multi-lumen tubes having various densities according to embodiments of the present disclosure. [Figure 8] FIG. 8 illustrates a distal end of an exemplary multi-lumen tube having variable stiffness according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Reference will now be made in detail to the aspects of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same or similar reference numbers will be used throughout the drawings to refer to the same or like parts. The term "distal" refers to the portion of the device that is furthest from a user when introducing the device into a subject (e.g., a patient). In contrast, the term "proximal" refers to the portion of the device that is closest to a user when placing the device in a subject.

[0009] The embodiments of the present disclosure may solve one or more limitations in the art. However, the scope of the present disclosure is defined by the appended claims, and not by the ability to solve a particular problem. In certain embodiments, the present disclosure is directed to a medical device that includes at least one multi-lumen feature (e.g., a tube) having at least two portions of variable stiffness or flexibility. Although the present disclosure may refer to one of a duodenoscope or an endoscope at different points, it will be understood that unless otherwise specified, a duodenoscope, an endoscope, a colonoscope, a ureteroscope, a bronchoscope, a laparoscope, a sheath, a catheter, an implant, a tube, a sheath, any suitable delivery device, or other medical device may be used in connection with aspects of the present disclosure.

[0010] Portions of a medical device that may have a different stiffness than other portions or remainder of the medical device may include any structure requiring such a different stiffness. For example, a tube may include an axial portion, such as a distal portion, that has a higher flexibility compared to the remainder of the tube or shaft. This may allow, for example, a distal articulation joint to be more flexible than a more proximal portion of the tube, allowing for easier distal steering. In another example, one or more portions of a cross section of the tube may have a different flexibility than other portions of the cross section. This may allow the tube to bend more easily in a particular plane where the cross section is most flexible for more efficient maneuverability. In another example, at least one lumen of a multi-lumen tube may have walls that are more flexible than walls that define other lumens of the tube. This may allow at least one lumen to more effectively perform a function, such as the delivery of processing tools, cables, fluids, etc. In further examples, any variable stiffness portion of the tube may be used in suitable combination with any other variable stiffness portion of the tube, for example, an axially distal portion having a different flexibility than a more proximal portion and / or variable stiffness present in the cross-section of the tube.

[0011] 1 illustrates an exemplary medical device 10 (e.g., an endoscope) according to an embodiment of the present disclosure. The medical device 10 has a proximal end 11 and a distal end 13. At or near the proximal end 11 is a handle 16 having one or more knobs 18, a lock 22, and a port 20. A shaft 12 extends from the distal end of the handle 16 to the distal end 13 of the device 10.

[0012] The shaft 12 is a tube of sufficient length and flexibility to access internal sites and traverse tortuous anatomical structures. The shaft 12 may be a single piece having one or more lumens. Alternatively, the shaft 12 may comprise multiple members, such as multiple tubes with single or multiple lumens coupled together. The multiple lumens 14 may extend through the shaft 12 from the proximal end to the distal end 13. The multiple lumens 14 may comprise any number of lumens desired and permitted based on constraints related to the cross-sectional area and desired properties of the shaft 12. For example, the lumens 14 may include lumens for inserting / delivering instruments, delivering fluids, applying suction, jacketing electrical cables or wires, jacketing wires for steering (connecting a handle to a distal portion), etc. As shown in FIG. 1, one or more of the multiple lumens 14 may open at a distal face of the shaft 12, for example, to deliver fluids or instruments distal to the end of the device 10. Additionally or alternatively, one or more of the lumens 14 may terminate proximally at the distal face of the shaft 12, or a cap 28 may be disposed at the distal end of the shaft 12 to close one or more of the lumens 14, e.g., to enclose electrical cables for imaging and illumination. Each of the lumens 14 may be substantially parallel to one another, such that the longitudinal axes of the lumens 14 are substantially parallel to one another and to the longitudinal axis of the shaft 12. The lumens 14 may have a variety of shapes (e.g., square, oval, circular, star-shaped, etc.) and sizes. The shaft 12 couples to a handle 16 at the proximal end of the shaft 12, allowing access to one or more of the lumens 14 through the handle 16 from one or more ports 20. Additionally or alternatively, the multiple lumens 14 may terminate inside the handle 16 and communicate with structures inside the handle and / or umbilical 26 for suction, irrigation, electronics, etc., as known in the art.

[0013] The medical device 10 may further include an articulation 24 for navigating tortuous anatomy and directing the distal-most end of the device 10 to a target site. The articulation 24 may be located at the distal end 13 of the shaft 12 or just proximal to the distal end 13. The articulation 24 may allow a user to bend or articulate the distal end 13 in any desired direction (e.g., up, down, left, and / or right) via means known in the art, particularly via manipulation of the knob 18 and control wires (not shown) housed inside the handle 16 and lumen 14 of the shaft 12. The articulation 24 may be a portion of the integral one-piece shaft 12. For example, the shaft 12 may comprise a section of sufficient axial length having material and flexibility properties as further described herein. In alternative embodiments, the articulation 24 may be a separate member coupled to the distal end of the shaft 12. In each embodiment, a cap 28 may be coupled to the distal-most end of the articulation 24.

[0014] The entire shaft 12, and / or one or more portions of the shaft 12 (e.g., articulation joint 24), may comprise tubing comprising polytetrafluoroethylene (PTFE) or expanded polytetrafluoroethylene (ePTFE). PTFE and ePTFE are materials commonly used in the medical device industry due to their various biocompatibility and mechanical properties.

[0015] PTFE tubes can be manufactured using various techniques commonly known in the art. Mostly, PTFE tubes are paste extrusion or ram extrusion. Figure 2 is a flow diagram of an exemplary paste extrusion process 300. In the first step 302 of the process 300, PTFE in powder form and a lubricant are mixed together and compressed at or below room temperature to obtain a billet.

[0016] One or more types of powdered form of PTFE may be used in the billet. For example, the billet may include a single type of PTFE in powder form, or may include different types of PTFE in powder form. For example, the billet may include two or more layers of different types of PTFE in powder form. Each of the layers may be the same depth or thickness, or may be of different depths or thicknesses.

[0017] In a further example, a cross-section of the billet may include a single type of PTFE in powder form, or different types of PTFE in powder form. For example, a first portion of the cross-section of the billet may include a first type of PTFE in powder form and a second portion of the cross-section of the billet may include a second type of PTFE in powder form. The first, second, etc. portions of the cross-section may be the same size or different sizes.

[0018] For example, the cross section may be divided into halves, thirds, quarters, etc. Each half, third, quarter, etc. may be the same size and / or shape or a different size and / or shape. For example, if the cross section of the billet is generally circular, the first quadrant may be about 90 degrees and the second quadrant may be about 90 degrees. Additionally or alternatively, the quadrants may be different degrees. Thus, the cross section of the billet may be symmetrical or asymmetrical. Thus, the resulting tube may have symmetrical or asymmetrical properties. A tube with asymmetrical properties may be useful, for example, to create a tube with one or more portions that have a higher sealing ability and / or higher flexibility.

[0019] In yet another example, the billet may include different layers and different portions of PTFE in powder form. For example, a first longitudinal length of the billet may include different layers of PTFE in powder form and a second longitudinal length of the billet may include different cross-sectional portions of PTFE in powder form. As described in more detail below, different types of PTFE in powder form may be utilized to help impart different properties or characteristics to the manufactured tube, for example, along the longitudinal length or radial width of the manufactured tube.

[0020] The billet is then forced into a die under high pressure and extruded at room temperature or slightly heated (step 304). According to embodiments of the present disclosure, any desired PFTE resin commonly known in the art may be used to manufacture the tube, depending on the desired properties of the resulting tube-based device. Additionally, lubricants or alternative additives known in the art may be added to the resin as needed to achieve the desired properties of the tube and device. Similar to the powder form of PTFE described above, lubricants or alternative additives may be added to different layers or different cross-sectional portions of the billet. The resulting tube is then subjected to a drying process to remove the lubricant. At this point, the tube is commonly referred to as "green PTFE / ePTFE tube." The tube then undergoes a sintering and cooling process (steps 308, 310, 312). During the sintering step 310, the tube may be subjected to a controlled tension or stretching process to minimize stretching after extrusion. Sintering, which involves heating the tube, allows for the coalescence of the PTFE resin particles, which provides strength and void reduction within the tube. The final product is a fully sintered PTFE tube that is typically wound onto a spool or cut to desired lengths (step 314).

[0021] ePTFE is a microporous version of PTFE, resulting in different mechanical properties. ePTFE may, for example, be softer and more flexible than PTFE. The manufacturing or forming process is the same as that of PTFE, with some differences. In particular, the PTFE tube is subjected to additional manufacturing or forming processes after the extrusion and drying processes described above. These additional processes include subjecting the tube to longitudinal and transverse expansion processes at a specific rate and elevated temperature, resulting in an amorphously fixed ePTFE tube.

[0022] ePTFE is used in medical applications, including as tubing, for a variety of reasons. For example, ePTFE can bend without kinking. This is due to the fibril and node microstructure of ePTFE. FIG. 3A shows an ePTFE tube 200 in a straight configuration with an exemplary fibril and node microstructure. The microstructure of the tube 200 includes masses of material (nodes 205) that run roughly parallel and perpendicular fibers (fibrils 210) that connect them. Pores 212 exist within the network of nodes 205 and fibrils 210. Pores 212 also include axially oriented fibrils 214. FIG. 3B shows the tube 200 in a curved configuration. During bending, at the inner arc 215, the nodes 205 compress the pores 212 and the fibrils 210, 214 compress. Along the outer arc 220, the fibrils 210, 214 are placed under tension and the size of the pores 212 increases. Taken together, this is known as foreshortening and allows the tube 200 to maintain its cross-sectional shape when curved. For example, the lumen in the tube 200 substantially retains its shape when curved, making the ePTFE tubes particularly suitable for use as shafts and tubing in a variety of medical applications.

[0023] As discussed above, various medical applications require multi-lumen tubes. FIG. 4 shows a tube 100 having multiple lumens 130 extending from a proximal end 105 to a distal end 110. The tube may have one or more separate axial sections 115, 120, 125 of varying density and flexibility. For example, section 115 may be of high density and low flexibility, and sections 120, 125 may be of reduced density and increased flexibility, or vice versa. Alternatively, sections 115, 125 may be of high density and low flexibility compared to section 120, or vice versa. The varying densities and flexibility of sections 115, 120, 125 may be achieved by layering and / or splitting a billet (not shown) from which tube 100 is extruded, for example, as discussed above. Additionally or alternatively, tube 100 may be subjected to additional processes to create sections of PTFE and ePTFE tubes of varying density and flexibility, as described below. The number of axial sections is not limited to three as shown in the figures. There may be more or fewer sections, for example, with different densities. Furthermore, the number of lumens 130 is not limited to the configuration shown. There may be more or fewer lumens, with varying sizes. Additional multi-lumen tubes according to embodiments of the present disclosure are described in more detail in Figures 7A-7E.

[0024] Embodiments of the present disclosure relate to processes for producing PTFE and ePTFE tube sections of various densities and flexibilities. In one example shown in Figures 5A and 5B, the process 400 begins with a green PTFE or ePTFE tube 405 (e.g., a starting tube), such as a multi-lumen tube 405. The entire length of the multi-lumen tube 405 is stretched and set in an amorphous state (step 410), resulting in a longer intermediate tube 410' with reduced density and increased flexibility along the entire intermediate tube 410'. Alternatively, to stretch the green tube 405 and set it in an amorphous state, the tube 405 may be partially sintered at a lower temperature and set in an amorphous state, or may be subjected to a higher or lower stretching rate. Sections may then be shrunk at different sintering levels. However, in an exemplary embodiment, once the tube is fully sintered or heated to or near its melting temperature, it is not further deformed in this step 410.

[0025] In the next step 415, a portion of the intermediate tube 410' is heated to an elevated temperature to a level that includes full sintering, while the remainder of the intermediate tube 410' is not heated. For example, the left hand axial portion of the intermediate tube 410' may be heated to render the portion 415' of the final tube 425 denser and less flexible compared to the remainder of the final tube 425. This densification process results in a linear contraction in the heated portion of the intermediate tube 410', i.e., the axial length of the portion 415' is shortened upon heating.

[0026] The degree of linear shrinkage may be controlled by applying a force, e.g., tension, to the intermediate tube 410′ in the longitudinal direction of the tube during this heating step 415. This may be accomplished, for example, by applying a weight to the intermediate tube 410′. This results in a variable stiffness tube, e.g., the final tube 425, where one portion 415′ is selectively linearly shrinkable (more dense and less flexible) and another portion is stretched and fixed in an amorphous state (less dense and more flexible). The optimal temperature used in step 415 may vary depending on the desired properties of the tube portions. For example, a portion may be heated at a temperature of about 350 to 370° C. for 5 seconds to an hour or more. However, a portion may be heated at a temperature of about 250 to 450° C. for 1 second to several hours. For example, a portion may be heated at a temperature of 250° C. or higher. In particular, increasing the temperature may decrease the time the portion needs to be heated. Step 415 differs from the standard heating or sintering step 310 (FIG. 2) in that the portion is first sintered or amorphously set at a temperature below the sintering temperature. The tube is also subjected to stretching, where a section of the tube is then brought to a higher temperature than before. To limit the shrinkage of the section, force is applied longitudinally and heat is applied only to the areas that will increase density. Radial compression may also be applied by a segmented interference mold, which compresses the tube and helps prevent it from springing back.

[0027] The amount of linear shrinkage (of the heated portion of step 415) may be controlled in a variety of additional ways. For example, a braided or woven wire tube may be placed rigidly around the outside of the intermediate tube 410' prior to heating in step 415. Tubes made from braided or woven wire have inherent compression and expansion limits based on various properties, including wire size and material, wire thickness, braid pitch / density, contact pressure of the braid against the intermediate tube 410', etc. The tube may also vary in any of the aforementioned properties along its longitudinal length. For example, the braid pitch / density may be different in the distal and proximal portions. Heating the intermediate tube 410' while some or all of it is surrounded by the braid may control / limit linear shrinkage of the intermediate tube 410'. The braid may be applied at any step after extrusion of the desired shape and drying of the portion. However, applying the braid after partial sintering or amorphous settling may be optimal since there is more structure present at these stages.

[0028] Similarly, a metallic coil may be wound around the intermediate tube 410' prior to heating in step 415. The coil has inherent compression and expansion limits based on various characteristics including the size and material of the coil, the pitch of the coil, the contact pressure of the coil against the intermediate tube 410', etc. By heating the intermediate tube 410' while it is partially or fully surrounded by the coil, the linear contraction of the intermediate tube 410' may be controlled / limited. As with the braid or knit pattern, the coil may be applied at any step after extrusion of the desired shape and drying of the part. However, applying the coil after partial sintering or amorphous set of the part may be optimal since there is more structure at these stages.

[0029] In one embodiment, by utilizing a braid, coil, or knit pattern during step 415, localized energy around the metal braid or coil provides localized heating and amorphous fixation to adjacent regions of the ePTFE tube. This can provide the resulting ePTFE tube with a three-dimensional pattern of variable density and variable flexibility that substantially matches the braid or coil pattern. The pattern can improve the bonding capabilities of the component surfaces due to the much greater surface area versus a smooth tube. These features may also provide radial differences that can improve hoop strength and alter the bending characteristics of the tube.

[0030] In an alternative process 500 shown in Figures 6A-B, the process begins with a green PTFE or ePTFE tube, such as a multi-lumen tube 505. In step 510, a first axial portion of the green tube 505 is heated to a fully sintered state, thereby increasing the density of the heated portion and decreasing the flexibility of the portion. Thus, an intermediate tube 510' resulting from step 510 includes a portion 502 and a remaining portion 504, where the portion 502 is denser and less flexible than the remaining portion 504. The sintered portion of the intermediate tube 510' may shrink or contract due to the sintering process.

[0031] In a subsequent step 515, a portion of the intermediate tube 510', for example the entire portion 504 that was not heated in step 510, may be stretched and set in an amorphous state, resulting in a decrease in density and an increase in flexibility in the portion 504. Different temperatures, times, and / or tensions may be applied to the tube to achieve different levels of sintering. Step 515 results in a final tube 525 having one portion 502 (the portion on the left hand side of FIG. 6B) and another portion 504' (the portion on the right hand side of FIG. 6B), where the one portion 502 is denser and less flexible than the other portion 504'. The first and second portions 502, 504' may be adjacent to each other (as shown) or may be separated. Each portion 502, 504' may be sintered to different temperatures in the corresponding steps 510, 515, thereby creating tubes of different densities and flexibility. Similarly, each section 502, 504' may be stretched under different degrees of tension, thereby changing the length, density, and flexibility of the corresponding section.

[0032] In an alternative manufacturing method (not shown), the entire tube may be stretched at a first temperature and a first stretch rate. Then, a portion of the tube may be stretched at a second temperature different from the first temperature and / or subjected to stretching at a second stretch rate different from the first stretch rate. This results in tubes with a range of densities and flexibilities similar to the resulting tubes described above.

[0033] Certain challenges may arise during the manufacture or formation of multi-lumen tubes with various densities and flexibilities, particularly ePTFE multi-lumen tubes with desired variations in density and flexibility. The large voids in the lumens of the tube may cause variations in the conduction of heat to the walls across the cross section of the tube. For example, when applying heat to the outer surface of the tube from outside the tube, the innermost wall defining the lumen may not heat to the same temperature as the outer wall due to the large voids of the channels in the tube. This may result in a variety of density and flexibility across the cross section of the tube, with the outermost wall of the tube being the densest and least flexible, while the innermost wall is relatively less dense and relatively more flexible. This may have some desirable qualities, such as the inner lumen being more flexible for a particular function, but may result in a tube that does not have uniform foreshortening when the tube is bent, as described in connection with Figures 3A and 3B. To maintain this symmetrical and uniform curvature throughout the multi-lumen structure, a uniform (or substantially uniform) density across the cross section may be desired.

[0034] Thermal conductivity to the inner portion of the multi-lumen tube is achieved by inserting a mandrel within the lumens during the heating / sintering / amorphous set steps to impart the desired thermal conductivity and achieve a cross-sectional pattern of the desired density and flexibility, whether uniform or non-uniform.

[0035] The length of the mandrel also creates a density / flexibility differential along the longitudinal axis. The mandrels may be solid rods made of metal with a diameter that matches the diameter of the lumen into which they are inserted. When using heat external to the tube to heat the tube, the metal rod mandrel conducts the heat to a more central region of the tube's cross section, resulting in a more uniform cross-sectional density and flexibility. Additionally or alternatively, the mandrels may be heated independently using a heat source directly coupled to the mandrel (e.g., at the exposed end of the mandrel) to apply additional heat to the interior of the tube. Each mandrel may be heated independently or all of the mandrels may be heated together.

[0036] Independent heating of the mandrels at different temperatures can also achieve desired patterns of varying density and flexibility across the cross section of the multi-lumen tube. The cross-sectional density and flexibility of the tube can be controlled via an inductively heated mandrel inserted through the lumen of the tube. For example, a mandrel may be strategically and selectively positioned inside one or more lumens and inductively heated to an appropriate temperature to create regions of varying density. This allows for control of the density and flexibility in the walls of the tube adjacent to and surrounding the lumens. In addition, the use of mandrels of different metals with different metallurgical properties, including different conductivities, can be used to heat the surrounding walls to a desired temperature. In some embodiments, one or more mandrels can be heated to a temperature of about 250° C. or higher.

[0037] Additionally or alternatively, application of heat to an outer portion of a single lumen or multi-lumen tube (e.g., flexible tube) may be accomplished by partially or completely surrounding the exterior surface of the flexible tube with a hollow tube. Depending on the desired density / flexibility differential or properties of the flexible tube, the hollow tube surrounding the flexible tube may be utilized as a heat sink or as a heat source.

[0038] For example, the hollow tube can have a cavity or lumen with an inner diameter that matches or approximates the outer diameter of the flexible tube, such that the flexible tube can be inserted into the cavity or lumen of the hollow tube such that a desired length of the tube is surrounded by the hollow tube.

[0039] Thus, a hollow tube surrounding a flexible tube may provide density / flexibility differentials along the length, axial, and / or radial direction of the flexible tube. For example, the hollow tube may be heated to a temperature of about 250° C. or greater. In an alternative embodiment, the hollow tube may be a heat sink, absorbing heat from the tube, for example, when the flexible tube or a mandrel inserted into the lumen of the flexible tube is heated.

[0040] In some embodiments, the hollow tube may be made from one or more metals. The materials comprising the hollow tube may be utilized to impart density / flexibility differences or different properties to the flexible tube. For example, a first length of hollow tube may comprise a first metal having a first conductivity and a second length of hollow tube may comprise a second metal having a second conductivity.

[0041] Thus, in some embodiments, as the flexible tube is heated or sintered, the hollow tube may absorb heat from the flexible tube, which helps impart different properties to the flexible tube in a radial direction (e.g., inside the cross section of the flexible tube) and / or a longitudinal direction (e.g., along the axial length of the flexible tube). For example, a first portion of the flexible tube inside a first portion of the hollow tube may have different properties than a second portion of the flexible tube inside a second portion of the hollow tube. For example, an outer portion of the flexible tube, or a portion of the flexible tube closer to the hollow tube, may be less sintered and therefore have a lower density than an inner portion of the flexible tube. In some embodiments, a first portion of the flexible tube inside a first portion of the hollow tube may have different properties than a second portion of the flexible tube inside a second portion of the hollow tube.

[0042] In an alternative embodiment, the hollow tube may be heated to a temperature of about 250° C. or greater. In this manner, the hollow tube may be utilized to impart different properties to the flexible tube in the radial and / or longitudinal directions. For example, the hollow tube or portions of the flexible tube closest to the heat source may be further sintered and therefore have a higher density.

[0043] In a further alternative embodiment, the density of the flexible tube in the radial and axial directions may be further controlled by inserting at least a portion of the flexible tube into a hollow tube and inserting one or more mandrels into the lumen of the flexible tube, as described above. The cross-sectional density and flexibility of the flexible tube may be further controlled, for example, via an inductively heated mandrel inserted through the lumen of the flexible tube. For example, to create regions of varying density, one or more mandrels may be selectively placed inside one or more lumens of the flexible tube and inductively heated to an appropriate temperature. In this manner, one or more mandrels may be used as a heat source, thus imparting desired properties to the resulting flexible tube.

[0044] The mandrel or mandrels may be used in conjunction with or in addition to the flexible tube. For example, a hollow tube surrounding the flexible tube may be used as a heat sink to absorb heat from the flexible tube and / or the mandrel. In this manner, the flexible tube may be heated and / or the mandrel or mandrels may be heated. Alternatively, the hollow tube may be used as a heat source. In this manner, the mandrel or mandrels may be used as a heat sink, thus imparting desired properties to the resulting flexible tube.

[0045] FIG. 7A shows an exemplary multi-lumen green tube 600A according to one embodiment prior to processing steps according to the present disclosure. Tube 600A includes lumens 630a, 630b, 630c, 630d and four channels or lumens 630e that are used for various working channels or control wires to control up, down, left and right steering. Placing mandrels only in lumens 630b and 630c and heating those mandrels, as in the example shown in FIG. 7B, creates a high density in the area that receives the greatest amount of heat and therefore can reach the highest temperature, such as region 610a. Region 610a may therefore have a high density and low flexibility compared to other portions of the cross-section of the resulting tube 600B. Region 610a may extend along the axial length of tube 600B.

[0046] Similarly, placing mandrels in lumens 630a, 630d as well as 630b, 630c results in a larger region 610b of material having a higher density and stiffness. Region 610b may therefore have a higher density and less flexibility compared to other portions of the cross-section of the resulting tube 600C. Region 610b may extend along the axial length of tube 600C.

[0047] As more mandrels are placed in additional lumens, the regions of material with higher density and stiffness increase. For example, placing mandrels in lumens 630a, 630b, 630c, 630d in addition to lumen 630e results in a larger region 610c of higher density. Region 610c may extend along the axial length of tube 600D. Finally, placing a mandrel in each lumen 630a- and sufficiently heating the mandrels results in region 610d of higher density and less flexibility. Region 610d may encompass substantially the entire cross section of tube 600E.

[0048] The denser regions (610a-d) are not limited to those described. For example, the denser regions may be controlled through placement of mandrels in any combination of lumens 630a-e, as desired, and may be non-concentric. For example, if a user desires the bottom portion of the tube to be denser than the top portion, the user can insert and heat mandrels in the bottom lumens 630e and 630c. This creates a density gradient within the cross-sectional portion of the tube, with denser regions near the bottom portion, at least adjacent lumens 630e and 630c.

[0049] Additionally, the region of relatively higher density may be controlled by the relative thermal conductivity and magnetic inductance of the mandrel (e.g., depending on the material of the mandrel) and / or the temperature of the heated mandrel. For example, heating the mandrel to a first temperature results in a first region of higher density, and heating the mandrel to a second, higher temperature results in a larger region of a second, higher density. The axial length of the region of higher density may be controlled by the length of the mandrel.

[0050] A wide variety of materials may be used for the mandrel and / or hollow tube, depending on the desired properties to be imparted to the flexible tube. For example, tungsten, bronze, brass, copper, silver coated copper, Inconel, Nitinol, various stainless steels (302, 304, 316, 420, etc.) as well as clad materials may be used. Additionally, different geometries of these materials may also be used.

[0051] FIG. 8 illustrates the distal end of an exemplary multi-lumen tube 800 with variable stiffness. FIG. 8 illustrates how an articulation joint can be created by inserting a mandrel into a selected lumen to create a preferred curvature region. For example, in this embodiment, an articulation joint with a bidirectional curvature can be created by placing mandrels in lumens 830b, 830d, 830e and heating the mandrels as described above. This process creates a tube 800 with at least two regions 810a, 810b of reduced density on either side of the tube 800 compared to the top and bottom portions (i.e., the regions adjacent to where the mandrels are placed). These at least two regions can have a lower density than the remaining perimeter. For example, the perimeter of the two regions can have a higher density than the at least two regions. The at least two regions can be spaced about 180 degrees apart about the circumference of the tube to achieve a bidirectional curvature in opposite directions, as shown. However, these regions may be spaced apart at various angles to achieve any desired steering direction (left and down, left and up, right and down, or right and up). The axial length of the portions may be controlled by varying the length of the mandrel. The lower density and therefore more flexible regions 810a, 810b are adjacent to lumens 830f that house the control wires, which are translated within these lumens 830f to cause bending in the direction of the arrows shown in FIG. 8. The bending direction is in the plane of the more flexible regions 810a, 810b, which aids in the bending action. It will be understood that creating two regions 810a, 810b of lower density is not limited to the scope of the present disclosure. For example, more or fewer regions of reduced or increased density may be created. Creating regions of reduced or increased density depends on the spacing and orientation of the lumens into which the mandrel is inserted.

[0052] Although the principles of the present disclosure are described herein with reference to illustrative examples for particular applications, it will be understood that the present disclosure is not limited thereto. Those skilled in the art and who have access to the teachings herein will recognize that all additional modifications, applications, and equivalent substitutions are within the scope of the examples described herein. Thus, the present invention should not be considered as limited to the foregoing description.

Claims

1. A medical device comprising a shaft, the shaft including a single tube defining a plurality of lumens, the single tube containing at least one of PTFE and ePTFE, the density of at least one of PTFE and ePTFE varying along the length of the single tube.

2. The density changes within the cross-section of the integrated tube. The medical device according to claim 1.

3. The density of the radially inner portion of the integrated tube is different from the density of the radially outer portion of the integrated tube. The medical device according to claim 2.

4. The integrated tube includes an articulated joint, and at least two regions separated from the periphery of the articulated joint have a lower density than the other regions of the periphery. The medical device according to claim 1.

5. The two aforementioned regions are separated by approximately 180 degrees with respect to the surrounding area. The medical device according to claim 4.

6. The integrated tube comprises an articulated joint, and the integrated tube further includes a proximal portion relative to the articulated joint, wherein the articulated joint is less dense than the proximal portion. The medical device according to claim 1.

7. The outermost surface of the aforementioned integrated tube is further surrounded by one of a braid or a coil, The medical device according to claim 1.

8. One of the braids or coils is at a temperature of at least 250°C. The medical device according to claim 7.

9. At least one of the wire pitch, material, and thickness in one of the braid or the coil varies along the length of one of the braid and the coil. The medical device according to claim 7.

10. The integrated tube further comprises at least one mandrel extending through at least one of the plurality of lumens, The medical device according to claim 1.

11. The aforementioned at least one mandrel is at a temperature of 250°C or higher. The medical device according to claim 10.

12. The integrated tube further comprises a plurality of mandrels extending through one or more of the plurality of lumens. The medical device according to claim 1.

13. Of the plurality of mandrels, the first mandrel is at a first temperature, and the second mandrel is at a second temperature different from the first temperature. The medical device according to claim 12.

14. The density of the proximal portion of the integrated tube is different from the density of the distal portion of the integrated tube. The medical device according to claim 1.

15. The medical device is an endoscope, the shaft is coupled to a handle at the proximal end of the shaft, and the plurality of lumens include lumens for a working channel and an articulating wire. A medical device according to any one of claims 1 to 14.

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