Dynamically stiffening composite medical structures

Abstract

The stiffening device includes an elongated flexible tube, a stiffening layer disposed over the elongated flexible tube, an outer layer over the flexible tube and the stiffening layer, and an inlet located between the elongated flexible tube and the outer layer and configured to be attached to a vacuum or pressure source. The stiffening device is configured to have a rigid configuration in which vacuum or pressure is applied through the inlet and a soft configuration in which vacuum or pressure is not applied through the inlet.

Description

[Technical field]

[0001] Claiming priority

[0001] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 308,044, entitled "DYNAMICALLY RIGIDIZING COMPOSITE MEDICAL STRUCTURES," filed February 8, 2022, and is incorporated by reference in its entirety herein.

[0002] Incorporation by Reference

[0002] The publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. [Background technology]

[0003]

[0003] Many types of elongated tubular medical devices are inserted into openings (natural or artificial) in the body for diagnosis and treatment. For example, these devices can include endoscopes, catheters, wires, sheaths, overtubes, cannulas, and trocars. These devices can include both manual tools and robotic systems. These devices are typically available in both flexible and rigid forms. Flexible and rigid devices have advantages and disadvantages. Flexible catheters or endoscopes are advantageous because they can reach virtually all major organs in the human body. However, flexible endoscopes and catheters rely on reaction forces generated by pushing the tissue of the body cavity being explored to navigate around corners or bends in the anatomy. When navigating in body regions with highly tortuous passageways, relatively open areas, friable elements that are easily dislodged, or passageways with variable (or large) lumen diameters, flexibility can be problematic because it can be difficult to reliably contact the outer diameter of the tube. Furthermore, very soft tubes may distort, buckle, prolapse, loop, or have difficulty accommodating additional tools or devices. Soft devices make precise tip movement difficult, can severely impair precise movement and control, and are not compatible with procedures requiring high tip loads. These issues can lead to damage, including long procedure times, trauma, complications, and death. Rigid devices can present their own challenges. Rigid devices can be difficult to navigate within the body and are simply not possible to navigate to a wide variety of locations. Advancement of rigid devices can cause damage, including significant anatomical distortion, trauma, complications, and death. Under certain circumstances, both soft and rigid devices can cause severely compromised clinical outcomes.

[0004]

[0004] It would therefore be beneficial to provide a selectively stiffening device that can controllably transition between a highly flexible and a highly rigid configuration. Of particular interest are the stiffening tubes described in U.S. Patent No. 11,135,398, entitled "DYNAMICALLY RIGIDIZING COMPOSITE MEDICAL STRUCTURES," which is incorporated herein by reference in its entirety. While such tools can provide safe, efficient and precise access to otherwise difficult to reach anatomical locations, it would be beneficial to modify all or specific areas of these devices that allow for improved compliance, enhanced softness or stiffness, reduced shape distortion, enhanced safety, ease of manufacture and / or increased reliability. Summary of the Invention [Problem to be solved by the invention]

[0005]

[0005] Apparatus and methods that can address these needs are described herein. [Means for solving the problem]

[0006]

[0006] Described herein are stiffening apparatus (e.g., devices, systems, etc.), as well as methods of using them. For example, described herein are stiffening devices including a coiled tube, sometimes referred to herein as an inner and / or outer coiled tube (e.g., ICWT or OCWT), including a tube of matrix material on which one or more coil supports are wound. The coil supports can be formed from wires, cables, etc., including ribbons of material. In some embodiments, the coiled tube can include a matrix material sandwiched between a first supporting wire coil region (e.g., a helical coil) and a second supporting wire coil region (e.g., a helical coil), where the first and second supporting wire coil regions are portions of the same component, such as a wire, that are folded back as a single continuous portion (e.g., a single continuous filament, ribbon, wire, etc.). For example, a first support wire coil region can be referred to as a proximal-distal winding, and the proximal-distal winding can be folded over (or under, in some embodiments) the distal-proximal winding to form a second support wire coil region.

[0007]

[0007] In any of these apparatus (e.g., devices, systems, etc.) described herein, the first and / or second support wire coil regions are contiguous where they intersect, but are not contiguous as they extend along the proximal-distal length of the apparatus. For example, the support coils may extend only partially (e.g., to the distal end) through the length of the elongate stiffening device, and not the entire length of the device. In some embodiments, the beginning of the first support wire coil region begins distal to the distal end region of the second support wire coil, or vice versa.

[0008]

[0008] The first and second coil regions may be wound in the same direction or in opposite directions. The pitch of the distal-proximal winding may be the same as or different from the proximal-distal winding. In some variations, the pitch of the distal-proximal winding may be uniform or may vary, and the pitch of the proximal-distal winding may be uniform or may vary. The coils may be made of the same material or different materials. The coils may have the same cross-sectional geometry or different cross-sectional geometry. Continuous winding allows the user to manufacture the tube with a single piece of wire, which can have manufacturing advantages. Continuous winding results in distal or proximal regions without broken wire, thereby eliminating the risk associated with outward or inward wire spreading, which can cause geometric distortions in the body or tip of the catheter and cause trauma to the patient or user.

[0009] Any of the devices described herein can be configured as components utilized in stiffening devices. They can be used in negative pressure or vacuum based systems, or in higher pressure systems (i.e., above 1 atmosphere, including positive pressure systems). The coil region can be used in systems where the coil region receives an external pressure, which creates a force tending to collapse the tube. The coil region can be used in systems where the coil region receives a vacuum compaction force.

[0010] Any of the devices described herein can be configured as stiffening devices that stiffen through expansion of one or more bladder regions, and the bladder regions of these devices (one or both sides of the bladder surface) can be configured to prevent sticking or other failure modes by including additives (e.g., lubricants, powders, etc.) and / or textures and / or coatings. For example, the bladder regions can include a lubricating material such as glycerin. In some embodiments, the bladder regions can be expanded with a material to reduce sticking. For example, the bladder regions can be expanded with a lubricating material.

[0011] Any of the devices described herein can be configured as stiffening devices formed from multiple layers (including radially arranged layers) configured to prevent delamination of the layers by including one or more bonding or adhesion layers. Adhesion layers can include layers that act as effective intermediate layers that can be particularly beneficial for bonding. For example, if layer A does not bond to layer C, adhesion layer B can be used to bond layer A to layer B, and layer B to layer C, thus essentially bonding layer A to layer C. Adhesion layers can be significantly thinner and may be continuous or discontinuous.

[0012] Any of the devices described herein can be configured as stiffening devices configured to enhance compliance by reducing tip stiffness. These devices can be configured to tune or adjust the softness of the distal tip by setting the spacing of various layers in the distal tip region.

[0013] Any of the devices described herein can be configured as stiffening devices that stiffen by expansion from a distal (or intermediate) end region rather than strictly or exclusively from a proximal end region.

[0014]

[0014] Any of the devices and methods described herein can be configured for use as a positionable, stable platform that can be used as an imaging landmark, computational landmark, or starting point for one or more medical procedures.

[0015] For example, described herein is a catheter device including an elongated flexible tube, the elongated flexible tube including an intermediate matrix layer, a first reinforcing coil extending from a proximal end to a distal end against an outer surface of the intermediate matrix layer, and a second reinforcing coil extending from a proximal end to a distal end against an inner surface of the intermediate matrix layer, the first reinforcing coil and the second reinforcing coil forming a continuous length of material that is folded back at the distal end of the intermediate matrix layer, and the elongated flexible tube further includes an elastomeric covering extending from a distal end to a proximal end over the second reinforcing coil. In any of these devices, one or more outer matrix layers can be disposed between the first reinforcing coil and the intermediate matrix layer, and / or between the second reinforcing coil and the intermediate matrix layer. The catheter device can be configured to stiffen the catheter when pressurized. The first reinforcing coil and the second reinforcing coil can include a wire. The wire can include a ribbon (e.g., a flat wire) having at least two surfaces substantially parallel to each other. An elastomeric coating may be fused to the intermediate matrix over the second reinforcing coil.

[0016] Any of these devices may include a second elastomeric coating over the first reinforcing coil and fused to the intermediate matrix.

[0017] Any of these devices can be configured as a stiffening catheter or stiffening member. For example, these devices can include a braided layer disposed over an elongated flexible tube, an outer layer covering the braided layer, and an inlet located between the elongated flexible tube and the outer layer and configured to be attached to a vacuum or pressure source, with the catheter device configured to have a rigid configuration in which vacuum or pressure is applied through the inlet (e.g., a pressure inlet or pressure port) and a flexible configuration in which vacuum or pressure is not applied through the inlet.

[0018]

[0018] Also described in this specification is a stiffening catheter comprising an elongate member including multiple layers and a bladder layer between the multiple layers, the stiffening catheter comprising a mechanism for preventing the bladder layer from adhering to itself or to surrounding layers, and the stiffening catheter configured to provide stiffness to the catheter when pressurized.

[0019]

[0019] These features can include texturing (e.g., a surface texture on the exterior or interior surface of the bladder layer and / or, optionally, on adjacent surfaces). For example, these features can include texturing of a surrounding layer. Alternatively or in addition, these features can include additives such as colorants, minerals, waxes, or lubricants. In some embodiments, these features include coatings and / or powders. For example, these features can include a braid layer adjacent to the bladder layer. These features can include channels or tubes extending along the bladder layer.

[0020] Also described herein is a stiffening catheter including an elongate member including a plurality of layers, the elongate member including an outer layer, an inner layer stacked on the outer layer, a reinforcing layer disposed between the outer layer and the inner layer, and a contact layer disposed between the outer layer and the inner layer and spanning the reinforcing layer, the outer layer being stacked through the contact layer onto the inner layer, the stiffening catheter configured to provide stiffness to the catheter when pressurized. The reinforcing layer can include a wire.

[0021]

[0021] The stiffening catheter can include an elongate member including multiple layers, the elongate member including an outer layer and an inner layer, the distal end of the outer layer being axially separated from the distal end of the inner layer by a distance of at least about 2 mm (e.g., about 1.8 mm, 1.7 mm, 1.5 mm, 1.4 mm, 1.3 mm, 1.2 mm, 1.1 mm, 1 mm, 0.9 mm, 0.8 mm, 0.7 mm, 0.6 mm, 0.5 mm, etc.), or, when the diameter of the catheter shaft is scaled, a distance greater than 0.25 times the diameter of the catheter, and further wherein the stiffening catheter is configured to convert the catheter from an unpressurized, soft form to a pressurized, rigid form when pressurized.

[0022] In any of these embodiments, the outer layer may comprise a reinforcing layer including wire. The inner layer may comprise an elongated flexible tube. The elongated flexible tube may be constructed as described above.

[0023] For example, the stiffening catheter may include an elongate member including multiple layers, the elongate member including a bladder layer and an inflation lumen extending between two of the layers to a distal end of the elongate member, the inflation lumen configured to provide pressure to the bladder layer from a distal end of the stiffening catheter, and the stiffening catheter further configured to convert the catheter from an unpressurized soft configuration to a pressurized rigid configuration when pressurized. The inflation lumen may include a flat tube. The inflation lumen may include nylon, polyethylene, thermoplastic polyurethane (tpu), or polyethylene terephthalate (e.g., PET). The inflation lumen may include a heat shrink tube. The inflation lumen may have a wall thickness of about 0.0013 cm (0.0005 inches). In some embodiments, the inflation lumen includes a one-way valve configured to allow application of vacuum rather than pressure. The inflation lumen may include a breather mechanism, such that the inflation lumen continues to pass vacuum and does not self-seal under negative pressure.

[0024] Also described herein is a method of treating a patient using the rigidified device as a stable platform for performing one or more additional procedures. For example, the method may include inserting a stiffening catheter into a body lumen of a patient in a flexible form, stiffening the stiffening catheter, visualizing a distal rigid end region of the stiffening catheter, and using the distal end of the stiffened stiffening catheter as a visual indicator from which subsequent instructions are computationally derived and as a stable base for performing one or more procedures within the patient.

[0025]

[0025] The stiffening device may include an elongated flexible tube, a braided layer disposed on the elongated flexible tube, a plurality of particles surrounding the braided layer, an outer layer covering the flexible tube, the braided layer, and the plurality of particles, and an inlet located between the elongated flexible tube and the outer layer and configured to be attached to a vacuum or pressure source, the stiffening device being configured to have a rigid form in which vacuum or pressure is applied through the inlet and a soft form in which vacuum or pressure is not applied through the inlet.

[0026]

[0026] The stiffening device can include an elongate member including multiple layers, the elongate member including an inner layer, a multiple particles disposed on the inner layer and optionally located within the stiffening layer, an outer layer covering the inner layer and the multiple particles, and an inlet located between the inner layer and the outer layer and configured to be attached to a vacuum or pressure source, the stiffening device configured to have a rigid form in which vacuum or pressure is applied through the inlet and a flexible form in which vacuum or pressure is not applied through the inlet.

[0027]

[0027] An elongated stiffening device having multiple layers can include an inner layer comprising an elongated flexible tube, a braided layer disposed on the elongated flexible tube along a first portion of the length of the elongated member, a plurality of particles surrounding the braided layer along a second portion of the length of the elongated member, an outer layer covering the inner layer, the braided layer, and the plurality of particles, and an inlet located between the inner layer and the outer layer and configured to be attached to a vacuum or pressure source, the stiffening device being configured to have a rigid configuration in which a vacuum or pressure is applied through the inlet and a soft configuration in which a vacuum or pressure is not applied through the inlet. The first portion can include the braided layer in addition to the plurality of particles. The second portion can include the plurality of particles without the braided layer. The plurality of particles can include a powder. The particles can act to increase the stiffness provided by the braid system because the particles are "tightly packed" when compacted. The particles can act to increase the stiffness provided by the braid system because the particles interlock between the blade elements when compacted. The properties of the plurality of particles may vary along the length of the elongated member, resulting in a varying stiffness along the elongated member when the device is in the rigid configuration.

[0028]

[0028] For example, the present specification describes a device including an elongated flexible tube, the device comprising: an intermediate matrix layer; a reinforcing coil adjacent to the intermediate matrix layer, the reinforcing coil including an outer reinforcing coil region extending from a first proximal region to a second distal region, and a second reinforcing coil region extending from the second distal region to the first proximal region, the outer reinforcing coil region and the inner reinforcing coil region forming a continuous length; and an outer layer.

[0029] Any of these devices can include a pressure inlet in fluid communication with the interstitial region between one or more of these layers. In particular, these stiffening devices can include a pressurized interstitial region between the reinforcement layers (e.g., an intermediate matrix layer and an intermediate or outer matrix layer) and a bladder layer configured to receive positive or negative pressure to stiffen the device. The intermediate matrix layer can be located between the outer and inner reinforcing coil regions.

[0030]

[0030] These devices may include an elastomeric covering over the inner reinforcing coil, extending from a first proximal region to a second distal region. The helix angle of the inner reinforcing coil region may have a different magnitude and opposite direction than the helix angle of the outer reinforcing coil region. The helix angle of the inner reinforcing coil region may have the same magnitude but opposite direction as the helix angle of the outer reinforcing coil region. The pitch of the inner reinforcing coil region may be different from the pitch of the outer reinforcing coil region. The cross-section of the inner reinforcing coil region may be different from the cross-section of the outer reinforcing coil region.

[0031] In any of these devices, the reinforcing coil can include a wire. For example, the reinforcing coil can include a ribbon having two substantially parallel faces. The elastomeric coating can be fused to an intermediate matrix that covers the second reinforcing coil. In some embodiments, the device includes a braided layer adjacent to the outer layer. In some embodiments, the braided layer is adjacent to the inner layer. In general, the stiffening device (which can include or be part of the stiffening device) can have a wall thickness that includes an inner reinforcing layer (e.g., an "inner coiled tube"), a bladder layer, a variable stiffness layer (e.g., a braided layer, a knitted layer, a woven layer, etc., that can include one or more filaments of multiple lengths that cross each other), an air gap, and an outer reinforcing layer (e.g., an outer coiled tube). The device can be configured to have a rigid configuration in which positive or negative pressure is maintained through a pressure inlet, and a flexible configuration in which positive or negative pressure is not maintained through the inlet. The pressure inlet is in fluid communication with the bladder layer. The air gap can be in fluid communication with one or more vents, for example, located at the proximal end of the device. The terms fiber, filament, and yarn may be used equivalently herein. A fiber may be composed of one filament (e.g., a monofilament) or may be composed of two or more filaments.

[0032] For example, described herein is a stiffening device that includes an elongated flexible tube having a wall thickness including one or more reinforcing layers each including an intermediate matrix layer, a reinforcing coil including an outer reinforcing coil region contiguous with an inner reinforcing coil region, and an outer matrix layer. The device is configured to have a rigid configuration in which a positive or negative pressure is maintained within the wall thickness, and a flexible configuration in which no vacuum or pressure is maintained within the wall thickness.

[0033]

[0033] As previously mentioned, described herein are devices that include a non-adhesive or anti-adhesive expandable bladder for stiffening the device. For example, the stiffening device can include an elongate member that includes multiple layers and a bladder layer between the multiple layers, the stiffening device includes one or more mechanisms for preventing the bladder layer from adhering to itself or to surrounding layers, and the stiffening device is configured to stiffen when pressurized. The one or more mechanisms can include one or more of texturing, additives, texturing of surrounding layers, lubricants, particulates, coatings, a braid layer adjacent to the bladder layer, and / or channels or tubes extending along the bladder layer.

[0034]

[0034] Also described herein are stiffening devices that include one or more cling layers. For example, any of the devices described herein can include an elongate member that includes multiple layers, the elongate member including an outer layer, an inner layer stacked on the outer layer, a reinforcing layer disposed between the outer layer and the inner layer, and a cling layer disposed between the outer layer and the inner layer and spanning the reinforcing layer, the outer layer being stacked on the inner layer through the cling layer, and the stiffening device configured to stiffen when pressurized. The reinforcing layer can include a wire.

[0035]

[0035] Also described herein are stiffening devices formed from multiple layers adapted to have a narrower or smaller profile. For example, any of the devices described herein can include an elongate member including multiple layers, the elongate member including an outer layer and an inner variable stiffness layer (e.g., braided, knitted, woven), the distal end of the outer layer being axially separated from the distal end of the inner variable stiffness layer by an axial distance of at least about one-quarter of the diameter (radial distance) of the device across the elongate member, and the stiffening device being configured to convert from an unpressurized soft configuration to a pressurized stiff configuration when pressurized. The distal end of the outer layer can be separated from the distal end of the inner variable stiffness layer by at least 2 mm. The outer layer can include a reinforcing layer including a wire. The inner layer can include an elongate flexible tube. The elongate member can further include a second inner layer, the distal end of the second inner layer being located between the distal end of the outer layer and the distal end of the inner layer. The second inner layer can include a helical counter-wound reinforcing coil.

[0036]

[0036] Also described herein are stiffening devices that are inflatable to stiffen and distribute the stiffening pressure to various points or along the length of the device. For example, these devices can include an elongated member including multiple layers, the elongated member including a bladder layer and an inflation lumen extending between two of the layers to a distal end region of the elongated member, the inflation lumen configured to provide pressure from the distal end of the stiffening device to the bladder layer, and the elongated member configured to convert from an unpressurized soft form to a pressurized rigid form when pressurized. Similarly, these devices can be used to enhance distal vacuum when used as a vacuum transmission conduit for a vacuum stiffening device. In some embodiments, these devices can utilize both negative and positive pressure in combination (on both sides of the bladder) for enhanced stiffening. The inflation lumen can include flat tubing. The inflation lumen can include PET. The inflation lumen can include heat shrink tubing. The inflation lumen can include a wall thickness of about 0.0013 cm (0.0005 inches) thick. The inflation lumen can include a one-way valve configured to allow application of vacuum but not pressure. The inflation lumen can include a breather mechanism configured to keep the inflation lumen open during application of vacuum.

[0037]

[0037] Also described herein are methods of using any of these devices as data or references. For example, a method of treating a patient may include inserting a stiffening device in a flexible form into a body lumen of a patient, the stiffening device extending its entire length from a handle to a distal end region, stiffening a portion or the entire length of the stiffening device by applying positive or negative pressure, visualizing the distal rigid end region of the stiffening device, and using the stiffened distal end region of the stiffening device as stable position data for performing one or more procedures within the patient. Stiffening the device may include applying positive pressure. Stiffening the device may include applying negative pressure. Any of these methods may include making one or more measurements from the stable position data.

[0038]

[0038] Any of the devices described herein may include particles in addition to a stiffening layer or braid to stiffen the device. For example, a stiffening device may include an elongated flexible tube, a braid layer disposed on the elongated flexible tube, a plurality of particles surrounding the braid layer, an outer layer over the flexible tube, the braid layer, and the plurality of particles, and an inlet located between the elongated flexible tube and the outer layer and configured to be attached to a vacuum or pressure source, the stiffening device configured to have a rigid configuration in which a vacuum or pressure is applied through the inlet and a soft configuration in which a vacuum or pressure is not applied through the inlet, and further in the rigid configuration, the plurality of particles enhance stiffness by being solidified within the braid layer.

[0039] For example, an elongated stiffening device having multiple layers may include an inner layer comprising an elongated flexible tube, a braided layer disposed on the elongated flexible tube along a first portion of the length of the elongated member, a plurality of particles surrounding the braided layer along a second portion of the length of the elongated member, an outer layer covering the inner layer, the braided layer, and the plurality of particles, and an inlet located between the inner layer and the outer layer and configured to be attached to a vacuum or pressure source, the stiffening device being configured to have a rigid configuration in which a vacuum or pressure is applied through the inlet and a flexible configuration in which a vacuum or pressure is not applied through the inlet. The first portion may include the braided layer in addition to the plurality of particles. The second portion may include the plurality of particles without the braided layer. The plurality of particles may include powders or particles of a specific size. The plurality of particles may vary along the length of the elongated member, resulting in a varying stiffness along the elongated member when the device is in the rigid configuration.

[0040] All of the methods and apparatus described herein in any combination are contemplated herein and can be used to achieve the advantages as described herein.

[0041]

[0041] A better understanding of the features and advantages of the methods and apparatus described herein may be obtained by reference to the following detailed description that sets forth exemplary embodiments and the accompanying drawings, in which: [Brief description of the drawings]

[0042] [Figure 1A] FIG. 1 shows an embodiment of a stiffening device. [Figure 1B]

[0043] FIG. 1A is a schematic diagram of an embodiment of a robotic device including a pair of nested stiffening members. [Figure 1C]

[0044] FIG. 1A is a schematic diagram of an embodiment of a robotic device including a pair of nested stiffening members. [Figure 1D]

[0045] FIG. 13 shows an example of multiple intersecting strand lengths that can form the variable stiffness layer of any of the stiffening devices described herein, illustrating a knitted variable stiffness layer having a weft knit pattern. [Figure 1E] FIG. 13 shows an example of a knitted variable stiffness layer having a warp knit pattern, illustrating examples of multiple intersecting strand lengths that can form the variable stiffness layer of any of the stiffening devices described herein. [Figure 1F] 1A-1C show examples of lengths of intersecting strands that can form the variable stiffness layer of any of the stiffening devices described herein, and show an example of a blade variable stiffness layer. [Figure 1G] FIG. 13 shows an example of a discontinuous braided variable stiffness layer, illustrating examples of multiple intersecting strand lengths that can form the variable stiffness layer of any of the stiffening devices described herein. [Figure 1H] FIG. 13 shows an example of multiple intersecting strand lengths that can form the variable stiffness layer of any of the stiffening devices described herein; and FIG. 14 shows an example of a woven stiffening layer formed from filaments that can be used as part of a stiffening-enabled device described herein. [Figure 2A]

[0046] 1A-1C show an example of a portion of a vacuum stiffening device described herein, illustrating a cross section of an exemplary vacuum stiffening member of the device. [Figure 2B] FIG. 2 is an enlarged view of a portion of a cross section showing the arrangement of layers in an unstiffened configuration, illustrating one embodiment of a portion of a vacuum stiffening device described herein. [Figure 3A]

[0047] 1 is a longitudinal cross-sectional view of a pressure stiffening device illustrating an exemplary pressure stiffening device. [Figure 3B] 1 is a cross-sectional view of a pressure stiffening device showing an exemplary pressure stiffening device. [Figure 4A]

[0048] FIG. 1 is a schematic cross-sectional view of one embodiment of an inner coiled wound tube (ICWT) as described herein. [Figure 4B] FIG. 4B shows an embodiment of a stiffening wire for an ICWT similar to that shown in FIG. 4A. [Figure 4C] FIG. 4B shows an embodiment of a stiffening wire for an ICWT similar to that shown in FIG. 4A. [Figure 5A]

[0049] 13A-13C show examples of inner coiled tubes with different coil angles. [Figure 5B] 13A-13C show examples of inner coiled tubes with different coil angles. [Figure 5C] 13A-13C show examples of inner coiled tubes with different coil angles. [Figure 6]

[0050] FIG. 2 is a schematic cross-sectional view of one embodiment of a pressure stiffening device. [Figure 7A]

[0051] FIG. 2 illustrates an example of a cross-section of a stiffening device described herein. [Figure 7B]

[0052] FIG. 1 shows an example of an inner layer of an outer stiffening device that includes one or more cling layers. [Figure 7C]

[0053] FIG. 1 shows an example of an inner layer of an inner stiffening device that includes one or more cling layers. [Figure 8A]

[0054] FIG. 13 is a cross-sectional view of a stiffening device having at least two layers with separated distal ends. [Figure 8B] FIG. 13 is a cross-sectional view of a stiffening device having at least two layers with separated distal ends. [Figure 8C]

[0055] 8C is a graph showing stiffness versus length of the stiffening device of FIGS. 8A and 8B. [Figure 9]

[0056] 1A-1C show an example of a stiffening device comprising an inflation lumen configured to inflate a bladder layer at a distal end of the device. [Figure 10]

[0057] 1 illustrates an example of a method for performing a medical procedure within the pulmonary vasculature using a stiffening device as a stabilization and reference or guidance base or computational guide. [Figure 11]

[0058] FIG. 13 illustrates an example of a stiffening device that includes a braided layer and a number of particles adjacent the braided layer to compress the bladder layer when stiffened. [Figure 12]

[0059] FIG. 13 shows an example of a stiffening device including a plurality of particles to compress a bladder layer when stiffened. [Figure 13]

[0060] FIG. 1 illustrates an example of a stiffening device including a plurality of particles in a first section and a braid layer in a second section of the stiffening device. [Figure 14]

[0061] FIG. 13 shows an example of a stiffening device including a plurality of particles and a braid layer in a first section of the stiffening device, and only a braid layer in a second section. [Figure 15A]

[0062] FIG. 13 is a schematic perspective view of an embodiment of a distal end region of a stiffening device having a variable pitch coiled tube for enhanced flexibility. [Figure 15B] 1A-1C are schematic side views of an embodiment of a distal end region of a stiffening device having a variable pitch coiled tube for enhanced flexibility. [Figure 15C] FIG. 13 is a schematic perspective view of an embodiment of a distal end region of a stiffening device having a variable pitch coiled tube for enhanced flexibility. [Figure 15D] 1A-1C are schematic side views of an embodiment of a distal end region of a stiffening device having a variable pitch coiled tube for enhanced flexibility. [Figure 16A]

[0063] FIG. 1 shows an example of a portion of a distal end region of a stiffening device, and is a schematic diagram of an example of a tip region that seals between an inner region (e.g., an inner coiled tube) and an outer region (e.g., an outer coiled tube). [Figure 16B] 1A-1C show an example of a portion of a distal end region of a stiffening device, illustrating an example of a reflowed polymer tip region configured to provide a smooth profile to the distal tip region. [Figure 16C] 16C and 16D are schematic diagrams illustrating an example of a method for forming a rolled and reflowed polymer tip region such as that shown in FIG. 16B, showing an example of a portion of a distal end region of a stiffening device. [Figure 16D] FIG. 13 shows an example of a distal end region of a portion of a stiffening device having a funnel-shaped reflowed polymer tip sealingly bonding the inner region to the outer region. [Figure 16E] FIG. 16C shows an example of a distal end region of a portion of a stiffening device having a rolled and reflowed polymer tip sealingly bonding the inner region to the outer region, similar to that shown in FIG. 16B. [Figure 17]

[0064] FIG. 2 is a schematic diagram illustrating a cross-section of one embodiment of a distal end region of a stiffening device described herein. [Figure 18]

[0065] FIG. 2 is a schematic diagram illustrating an example of a cross-section of an example of a proximal end of a stiffening device described herein. [Figure 19]

[0066] FIG. 13 is a schematic diagram illustrating one embodiment of the distal end region of the device in which the lower coils of the inner coiled tube are radially redirected in the distal end region to enhance flexibility and prevent collapse of the distal end. [Figure 20]

[0067] 1A-1C are schematic diagrams illustrating an example of a distal end region of a stiffening device in which a bladder (e.g., a pressure bladder) has a thicker distal end region within a layered structure. [Figure 21A]

[0068] FIG. 13 is a schematic diagram illustrating one embodiment of a pair of nested stiffening members configured to bend at their distal end regions (e.g., a "parallelogram" bend) without the outer stiffening member compressing laterally. [Figure 21B] FIG. 2 is a schematic diagram showing bending of a parallelogram. [Figure 21C] FIG. 2 is a schematic diagram showing bending due to compression. [Figure 21D1] FIG. 13 illustrates bending without compressing the length of the sides. [Figure 21D2] FIG. 13 illustrates bending without compressing the length of the sides. [Figure 21E] FIG. 13 shows an example where a portion of the stiffening member follows a curved member and the area of ​​bending is due to bending of a parallelogram. [Figure 21F] FIG. 13 is a schematic diagram of one embodiment of a device configured to bend by parallelogram bending, in which the ICWT has dual wire reinforcement, with one of the wires extending beyond the other. [Figure 21G] FIG. 13 is a cross-sectional view of a device configured to bend by parallelogram bending. [Figure 22A]

[0069] 1A-1C are schematic diagrams illustrating an example of an axial adjuster configured to couple to a proximal end of a stiffening member to relieve axial stress when stiffening the member; [Figure 22B] FIG. 22B is a perspective view of a cross section of the axial adjuster of FIG. 22A, illustrating generally one embodiment of an axial adjuster configured to couple to a proximal end of a stiffening member to relieve axial stress when stiffening the member. [Figure 22C] FIG. 22C is a perspective view of the axial adjuster of FIGS. 22A and 22B, illustrating generally one embodiment of an axial adjuster configured to couple to a proximal end of a stiffening member to relieve axial stress when stiffening the member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043]

[0070] In general, described herein are stiffening apparatuses (e.g., devices, systems, etc.) that can be configured as or can be configured to assist in the transport of catheters or scopes (e.g., endoscopes) or other medical instruments through portions of body lumens, including curved or looped portions of the body, such as the gastrointestinal tract (upper, lower (colon), middle (small intestine), and ducts (bile duct and pancreatic duct)), urinary tract, pulmonary vasculature, venous and arterial vasculature, and neurovascular structures, and methods of using them. In particular, described herein are stiffening devices that include one or more reinforcing layers formed as coiled tubing. For example, these stiffening devices can include inner coiled wound tubing (ICWT) and / or outer coiled tubing (OCWT). In some embodiments, the coiled tubing includes a reverse wound coil, wire, or ribbon wound in a reverse direction over a middle layer (e.g., a cling layer in some embodiments), with both the outer and inner wound coils formed from a single continuous piece (e.g., filament, wire, etc.). For example, the inner coiled tube can include multiple layers, and the inner coiled tube itself can form a layer of the wall diameter of the stiffening device. The multiple layers of the inner coiled tube can include an intermediate matrix layer, a pair of counter-wound coils, and can be arranged to provide unique attributes. A reinforced inner coiled tube can be particularly useful in variations where the inner coiled tube withstands pressure applied to stiffen the variable stiffness layer, and the variable stiffness layer can be externally pressurized by applying pressure to press a bladder layer against the variable stiffness layer.

[0044]

[0071] Any of the devices described herein can be configured as stiffening devices that stiffen by negative (vacuum) or positive pressure and / or expansion or contraction of one or more bladder regions. The bladder regions of these devices can be configured to prevent adhesion or other failure modes by including additives (e.g., lubricants, etc.) and / or textures (e.g., grooves, channels, ridges, etc.) and / or coatings (e.g., lubricous coatings, hydrophilic coatings, hydrophobic coatings, etc.) and / or particles or particulates.

[0045]

[0072] Any of the devices described herein can be configured as stiffening devices formed from multiple layers (including radially arranged layers) configured to prevent delamination of the layers by including one or more bonding or cling layers. As used herein, a cling layer can form a layer that clings other layers together. For example, if layer A does not bond well to layer C, the system can be configured such that layer A can be bonded to layer B, which can be bonded to layer C, such that layer B can act to "cling" layer A to layer C.

[0046]

[0073] Any of the devices described herein can be configured as stiffening devices configured to enhance tracking by reducing tip stiffness. These devices can be configured to tune or adjust the softness of the distal tip by setting the axial and radial spacing of the various layers in the distal tip region. Tip softness and trackability can be important performance characteristics for devices including catheters or endoscopes. This can be particularly useful for mother-daughter devices, or nested devices such as endoscopes within overtubes, or catheters within catheters. In general, devices with stiff tips typically do not track well. Often, terminating multiple layers at the same distal axial location works to create a stiff tip. By axially spacing the distal terminations of the layers, the softness of the distal tip region can be tuned for enhanced trackability. These axial offset distances can be set distances (e.g., 2 or 3 mm) or can be a percentage of the catheter diameter (e.g., 1 / 4 the catheter diameter, 1 / 2 the catheter diameter, 1x the catheter diameter, 2x the catheter diameter, etc.).

[0047]

[0074] Any of the devices described herein can be configured as stiffening devices that stiffen by expansion of the distal (or some intermediate point) end region, rather than strictly or exclusively from the proximal end region.

[0048]

[0075] Any of the devices and methods described herein can be configured for use as a positionable, stable platform with a tip that can be used as an imaging landmark, computational landmark, (ultrasound, CT, fluoroscopy, MRI, echo), or starting point for one or more medical procedures. The imaging landmark can be by density (e.g., gold, tungsten, tantalum, platinum, osmium, or iridium rings) and / or magnetic properties (e.g., embedded magnetic elements, etc.). This can yield data from which subsequent procedural computational instructions can be derived.

[0049]

[0076] In general, any of the devices and methods described herein can be used in combination with any of these features and methods of use thereof. For example, the same device can include an ICWT that includes counter-wound layers, ribbons, or wires with an intermediate (e.g., adhesion) layer sandwiched therebetween, both the outer and inner wound coils are formed from a single continuous piece, and / or can include multiple layers (including radially arranged layers) configured to prevent delamination of the layers by including one or more bonding or adhesion layers, and / or can include a bladder region configured to prevent adhesion or other failure modes by including additives (e.g., lubricants, etc.) and / or textures and / or coatings.

[0050]

[0077] The stiffening devices described herein can be long, thin, hollow, and can transition quickly from a soft configuration (i.e., relaxed, pliable, or flexible) to a rigid configuration (i.e., stiff and / or retains its shape when stiffened). In some embodiments, the stiffening apparatus can include multiple layers (e.g., coil or reinforcement layers, slip layers, variable stiffness layers, bladder layers, and / or sealing sheaths) that can combine to form the walls of the stiffening device. The stiffening device can transition from a soft to a rigid configuration, for example, by applying a vacuum or pressure to or within the walls of the stiffening device. With the vacuum or pressure removed, the layers can easily shear or move relative to one another. With the vacuum or pressure applied, the layers can transition to a state that exhibits substantially enhanced resistance to shear, movement, bending, torque, and buckling, thereby providing stiffening to the system.

[0051]

[0078] The embodiments of the stiffening device described herein can be selectively and controllably stiffened using pressure (positive pressure) and / or negative pressure and adapted to perform the reduction described herein. The devices described herein can stiffen and in some variations non-rigidify the device using one or both of vacuum (negative) and positive pressure, which can be applied to the stiffening device and can be applied simultaneously. Positive and / or negative pressure can be applied to one or both sides of the bladder layer to stiffen and / or non-rigidify. In some embodiments, positive and / or negative pressure can be applied simultaneously to different regions of the device and its various layers and cross sections. However, the features and methods described herein are not limited to pressure (positive or negative) stiffening devices, and the methods described herein can be used with any suitable stiffening device.

[0052]

[0079] The stiffening (e.g., selective stiffening) devices described herein can provide stiffening for a variety of medical applications, including catheters, sheaths, scopes (e.g., endoscopes), wires, overtubes, trocars, or laparoscopic instruments. The stiffening devices can function as separate add-on devices or can be incorporated into the body of a catheter, sheath, scope, wire, or laparoscopic instrument. The devices described herein can also provide stiffening to non-medical structures. The stiffening devices described herein can also be non-tubular (including planar) stiffening structures.

[0053]

[0080] An exemplary stiffening device is shown in FIG. 1A. The system shown includes a stiffening device 300 having a wall with multiple layers, including a variable stiffness layer (e.g., braided, knitted, woven, etc.), an outer layer (a portion of which is cut away in this example (341) to show the underlying braid), and an inner layer. The inner layer can be an inner coil wound tube (ICWT). In general, any of these devices can include a leak-proof ICWT that can provide a consistent circumferential cross-section while resisting radial compression. Any of these devices can further include a proximal end that can be configured as a handle 342 having a vacuum or pressure inlet 344 (collectively referred to as a pressure inlet) for supplying vacuum (negative pressure) or positive pressure to the stiffening device 300. An actuation element 346 (e.g., a control such as a switch, button, etc.) can be used to turn the vacuum or pressure on and off, thereby transitioning the stiffening device 300 between the soft and rigid configurations. The distal end 339 of the stiffening device 300 (including the distal end region) can be smooth, flexible, and atraumatic to facilitate distal movement of the stiffening device 300 through the body. Additionally, the device (including the tip 339) can be tapered from the distal end to the proximal end to further facilitate distal movement of the stiffening device 300 through the body. In this example, the stiffening device is configured as an overtube, although other configurations may be used. The stiffening device can have a constant inner or outer diameter over its length, or can be tapered, or can have local sections of variable inner or outer diameter.

[0054]

[0081] In general, any of these devices can be configured as a robotic device that includes one or more (e.g., a pair of nested) stiffening members. FIG. 1B shows a schematic of an example of a robotic device that includes a pair of nested stiffening members that can be moved (e.g., telescopically) relative to one another. For example, in FIG. 1B, the inner stiffening member 3005 can be steerable and can move within an internal lumen of the outer stiffening member 303, which is nested within the outer stiffening member 303, and the inner and outer stiffening members can move axially and rotationally relative to one another. The device shown in FIG. 1B also includes a robotic controller 307 coupled to the proximal ends of the inner and outer stiffening members and configured to drive the movement (axial and / or rotational movement) of each of the inner and outer stiffening members. The robotic controller can include circuits such as control circuits, feedback circuits, pressure control circuits, one or more actuators (e.g., motors), and inputs (e.g., keyboard, buttons, etc.) to control and coordinate the movement of the inner and outer stiffening members. The controller can include or be coupled to a positive and / or negative pressure source. The robotic controller can be configured to advance and retract the apparatus in a controlled path by selectively alternatingly stiffening and non-rigidifying the inner and / or outer stiffening members while moving (e.g., advancing and / or retracting) the inner and outer stiffening members relative to one another to set a path for the nested device, as shown in FIG. 1B.

[0055]

[0082] FIG. 1C shows another embodiment of a robotic device, also including a pair of nested outer and inner stiffening members. FIG. 1C shows details of an embodiment of a robot controller configured to control the operation of the robot. In this exemplary device 9300z, the outer stiffening member 9300 and the inner stiffening member 9310 can be terminated together in the robot controller. In some embodiments, the robot controller can be configured as a cassette 9357 that can engage a separate robot driver (not shown in FIG. 1C) and can actuate steering (e.g., of a distal end region of one or both of the inner and / or outer stiffening members), advancement, and / or rotation of one or both of the inner and / or outer stiffening members.

[0056]

[0083] 1C, the outer stiffening device 9300 can be movable relative to the inner stiffening device 9310 by rotation of a disk 9389 attached to the cassette 9357. For example, the disk 9389 can be a pinion and the outer stiffening device 9300 can have an external rack 9382 with a number of tiny teeth. Rotating the disk 9389 against the teeth 9382 can advance the outer stiffening device 9300 forward or backward relative to the inner stiffening device 9310. In some embodiments, the possible movement or translation of the stiffening devices 9300, 9310 is limited by the size or design of the cassette 9357.

[0057]

[0084] The cassette 9357 may further include additional disks 9371a, 9371b connectable to cables 9363a, b, respectively, for steering (e.g., bending or flexing) the tip of the inner stiffening device 9310 (and / or the outer stiffening device 9300). Other steering mechanisms (e.g., pneumatic, hydraulic, shape memory alloy, EAP (electroactive polymer), or motor) are also possible. Again, in embodiments with different steering mechanisms, one or more disks (e.g., disks 9371a, 9371b) in the cassette 9357 may be used to actuate the steering.

[0058]

[0085] The cassette 9357 may further include bellows 9303a, 9303b that may be connected to the pressure gaps of the inner stiffening device 9310 and the outer stiffening device 9300, respectively. In this example, the bellows 9303a, 9303b may be compressed to drive fluid through the pressure line 9305z, increasing the pressure in the pressure gaps of the inner stiffening device 9310, 9300, causing the stiffening devices 9310, 9300 to become stiff. The actuation of the bellows 9303a, 9303b may be applied sequentially and / or simultaneously. One or more linear actuators (e.g., on the cassette 9357 or on the driver) may be configured to actuate the bellows 9303a, b. Alternatively, the devices 9300, 9310 may be stiffened and unstiffened by one or more sumps or pressure sources (e.g., via the pressure line 9305z). Other mechanisms for causing stiffening of the inner and outer stiffening devices 9310, 9300 are possible. For example, in some embodiments, the cassette 9357 can include a syringe or other container containing a fluid that can be delivered to the inner and outer stiffening devices 9310, 9300 to apply a stiffening pressure. In some embodiments, the syringe or other container can be used to withdraw fluid within the cassette 9357, thereby creating a vacuum that can be applied to the inner and outer stiffening devices 9310, 9300.

[0059]

[0086] The cassette 9357 may include a connector 9315y for connecting to additional lumens and / or wiring in the inner stiffening device 9310. The connector 9315y may include connections for delivering both suction and water to the tip of the inner stiffening device 9310. The connector 9315y may include an electrical connector for connecting a camera attached to the tip of the inner stiffening device 9310 to an external monitor and / or video processing unit. The connector 9315y may include a mechanical connector that connects to a hollow tube (e.g., a working channel) that runs all the way to the tip of the inner stiffening device 9310. By including the connector 9315y, control of all components of the system 9300z may be achieved using the cassette 9357.

[0060]

[0087] The disks 9389, 9371a, 9371b and cams 9374a, 9374b (or corresponding bellows) may be accessible from the bottom of the cassette 9357. The disks 9389, 9371a, 9371b and / or cams 9374a, 9374b may have features such as splines, pins, or teeth to transmit torque. These features may allow the disks 9389, 9371a, 9371b and / or cams 9374a, 9374b to be manipulated (e.g., by a drive unit / robot driver).

[0061]

[0088] In any of the devices described herein, the variable stiffness layer can include multiple strand lengths that cross over one another, including overriding one another, and can stiffen when compressed. Herein, the variable stiffness layer can be formed from one or more strands that form multiple strand lengths, which can be knitted, woven, braided, etc. Figures 1D-1G show examples of knitted, woven, and braided materials, respectively.

[0062]

[0089] For example, Figures 1D-1E show two different knitted fabrics 600, 600' that can be used to form a stiffening layer, also referred to herein as a variable stiffness layer. Figure 1D shows a weft knit. In this example, the knitted fabric is formed from one or more lengths of yarn (which can be a continuous yarn made of multiple separate yarns including broken / cut yarns) to form stitch loops 602, each of which includes a head region 604, a pair of legs 606, and first and second feet 608, each foot engaging the head of a stitch loop in a course above or below the original stitch loop course. The connection between the feet of adjacent stitch loops can be called a sinker (if the fabric is rotated 180 degrees, the sinker can also correspond to the head). In Figure 1D, the wale direction 612 runs up and down, and the course 610 runs from right to left. Typically, a wale is a row of loops running lengthwise, which in Figure 1D corresponds to the warp yarns of the fabric. A course is a row of cross-directional loops that corresponds to the weft of the resulting knitted fabric.

[0063]

[0090] FIG. 1E shows an example of a warp knit 600'. In this example, the warp knit also has a course 610' and wale 612' orientation, but the foot of each loop engages the head region of the knit loop in the offset row (course direction) as shown, forming a pattern of overlap 612 and underlap 614 lengths. The knitted variable stiffness layer (stiffening layer) described herein can use any suitable pattern and can be oriented in a direction (course or wale direction) relative to the elongated axis (length) of the device. For example, the knitted structure (knitted variable stiffness layer) can be configured such that the wale direction of the knit runs along the long axis of the flexible tube. Alternatively, the knitted structure can be configured such that the wale direction of the knitted structure is perpendicular to the long axis of the flexible tube. Depending on the stitch length (y) and / or spacing between loops (n) relative to the loop diameter (p) that may be involved, it may be beneficial to position the knitted variable stiffness layer (stiffening layer) such that either the wales or courses are oriented parallel or perpendicular to the long axis of the elongated body of the stiffening device. In any of the examples described herein, the knitted structure can include an average loop length that is greater than the loop width. For example, the loop length can be greater than or equal to 2 times (e.g., 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 20 times, 40 times, 60 times, 80 times, 100 times, or more) the average loop width. Knitted fabrics (including knitted tubes) can be particularly useful in the stiffening devices described herein because they can stretch and compress without buckling or wrinkling when bent.

[0064]

[0091] Any of the stiffening devices described herein (either nested systems or methods including them) can include a woven stiffening layer. For example, a woven fabric can include multiple parallel fiber lengths, which form a set of intersecting fiber lengths. The fibers can cross each other at an angle of 90 degrees, but this angle can vary (e.g., about 30 degrees to 150 degrees, 45 degrees to 135 degrees, 50 degrees to 130 degrees, 70 degrees to 110 degrees, 80 degrees to 100 degrees, etc.). The pattern of intersecting filament lengths (e.g., an array of filament lengths) can include individual filament lengths crossing above and below each other. For example, the pattern can include an under-over pattern, a once over and once under pattern, a two over two under pattern, a two over and once under pattern, etc. As described with respect to the knitted stiffening layer above, any suitable fiber (e.g., twisted yarn) can be used to form the stiffening layer. For example, the fiber can be a multifilament fiber including multiple bundles of filaments forming each twisted yarn. The weave pattern can be of any desired tightness (e.g., pore size) Generally, a number of different length fibers can be used to form the weave pattern.

[0065]

[0092] 1F and 1G show examples of braided stiffening layers. In FIG. 1F, a braid 650 is formed from a plurality of fibers 668, 678 arranged in an over and under pattern with a braid angle relative to the long axis (e.g., the long axis of the device when included as a stiffening layer). In general, the braid angle (relative to a centerline along the central axis) of the braided stiffening layer (tube) can be 45 degrees or less (e.g., less than 45 degrees, less than 40 degrees, less than 40 degrees, less than 35 degrees, less than 35 degrees, less than 30 degrees, less than 20 degrees, less than 20 degrees, etc.). In FIG. 1F, the different filaments forming the braided layer are continuous and unbroken. However, in some embodiments, it may be beneficial to include breaks or cuts, as shown in FIG. 1G. In this example, the material includes multiple breaks or cuts 688 in the braided strands. While such an arrangement may not be desirable in a braid used as part of a textile or even a medical device, in the context of a stiffening layer, this disordered (e.g., broken or cut) arrangement may be beneficial. Thus, in FIG. 1G, the braid pattern 650' forming the stiffening layer (e.g., stiffening tube) can enable high stiffening in the actuated state while enhancing softness in the non-rigid form. Thus, in FIG. 1G, the strands 668, 678' cross over and under each other in the braid pattern shown, but are periodically cut 688 along their length. The number or density of cuts can vary, and in some embodiments, a fiber can be cut every time it crosses over or under another fiber, and in other embodiments, a fiber can be cut every two (or three, or four, or five, or more) crosses. The cut pattern can be non-uniform. In some embodiments, it can be beneficial to distribute the cuts or breaks at a density such as about one cut / break per three crossings (e.g., 2-25 crossings, 3-20 crossings, etc.).

[0066]

[0093] Any of the stiffening devices (systems or methods including them) described herein can include a woven variable stiffness layer (e.g., stiffening layer). FIG. 1H shows one example of a woven stiffening layer 705 that can be used as a variable stiffness layer of a stiffening device. In FIG. 1H, the woven fabric includes a plurality of parallel fibers or filaments 718, 728 that form a set of intersecting lengths, where the fibers cross each other at an angle of about 90 degrees in FIG. 1H, but this angle can vary (e.g., about 30 degrees to 150 degrees, 45 degrees to 135 degrees, 50 degrees to 130 degrees, 70 degrees to 110 degrees, 80 degrees to 100 degrees, etc.). The pattern of intersecting filament lengths (e.g., an array of filament lengths) includes individual filament lengths that cross over and under each other as shown, with a first filament length 718 crossing over a second filament length 728 and crossing under a third filament length. In this embodiment, the pattern shown in FIG. 1H is an under-over pattern, but for other embodiments of the stiffening layer, the pattern may be different. In some embodiments, the pattern may be 2 over 2 under, or 2 over and 1 under, etc. Any suitable fibers (e.g., filaments, yarns, etc.) may be used to form the variable stiffness layer. The fibers may be multifilament fibers that include multiple bundles of filaments forming each fiber. In some embodiments, the fibers (yarns, filaments, etc.) are monofilaments. The weave pattern may be of any desired tightness (e.g., pore size).

[0067]

[0094] Other stiffening layers (e.g., knitted, woven, etc.) may also include breaks or cuts, which may be formed during fabrication by laser cutting, mechanical cutting, or any other suitable cutting technique.

[0068]

[0095] After being stiffened, the stiffening device can set to the shape it had before the vacuum or pressure was applied, and the stiffening process can be performed without changing the shape of the device during the transition from soft to rigid, i.e., the stiffening device does not straighten, bend, or otherwise substantially change its shape (e.g., it may stiffen in a looped form, a serpentine form, a curve, etc.). When the vacuum or pressure is released, the braids or threads in the layers forming the device can unlock relative to each other and move again to allow for less force bending of the stiffening device (i.e., enhanced softness). When the stiffening device is made more flexible by the release of the vacuum or pressure, it can continue to maintain the shape it had before the vacuum or pressure was released, i.e., the stiffening device does not straighten, bend, or otherwise substantially change its shape. Thus, the stiffening devices described herein can transition from a flexible, less rigid form to a stiffer, more rigid form by restricting the movement between the threads of the braid (e.g., by applying a vacuum or pressure).

[0069]

[0096] In some embodiments, the stiffening devices described herein are configured to rapidly switch between the stiff and soft configurations with an indefinite number of transition cycles. In some embodiments, the degree of stiffening (e.g., stiffness) of the device can also be adjusted, for example, by adjusting the positive pressure (in positive pressure stiffening embodiments) or vacuum (in vacuum stiffening embodiments). As interventional medical devices become longer and inserted deeper into the human body, and as they are expected to perform more precise therapeutic procedures, the need for precision and control increases. The selective stiffening devices described herein (including the selective stiffening overtube) are advantageous because they can provide both the benefits of flexibility (when needed) and stiffness (when needed). Additionally, the stiffening devices described herein can be used with conventional endoscopes, colonoscopes, robotic systems, and / or navigation systems, such as those described in International Patent Application No. PCT / US2016 / 050290, filed September 2, 2016, entitled "DEVICE FOR ENDOSCOPIC ADVANCEMENT THROUGH THE SMALL INTESTINE," which is incorporated by reference in its entirety.

[0070]

[0097] The stiffening devices described herein may additionally or alternatively be any of the stiffening devices disclosed herein, including any of the following: International Patent Application No. PCT / US2016 / 050290, filed September 2, 2016, entitled "DEVICE FOR ENDOSCOPIC ADVANCEMENT THROUGH THE SMALL INTESTINE," published as WO2017 / 041052; International Patent Application No. PCT / US2018 / 042946, filed July 19, 2018, entitled "DYNAMICALLY RIGIDIZING OVERTUBE," published as WO2019 / 018682; International Patent Application No. PCT / US2020 / 018934, entitled "DYNAMICALLY RIGIDIZING COMPOSITE MEDICAL The present invention may include any of the features described in connection with International Patent Application No. PCT / US2019 / 042650, filed July 19, 2019, entitled "DYNAMICALLY RIGIDIZING COMPOSITE MEDICAL STRUCTURES," and International Patent Application No. PCT / US2020 / 013937, filed January 16, 2020, entitled "DYNAMICALLY RIGIDIZING COMPOSITE MEDICAL STRUCTURES," which are incorporated by reference in their entireties.

[0071]

[0098] The stiffening devices described herein can be provided in multiple configurations, including different lengths and diameters. In some embodiments, the stiffening device can include a working channel (e.g., to allow passage of typical endoscopic tools within the body of the stiffening device), a balloon, a nesting element, and / or a side-loading mechanism.

[0072]

[0099] For example, a stiffening apparatus 100 (also referred to as an apparatus, e.g., system and / or device, including a stiffening member) can be configured to be stiffened by application of a vacuum, e.g., negative pressure. These apparatuses can generally be formed from layers configured to form a laminated structure upon application of negative pressure, such that one or more braided or woven layers can be reversibly melted into a flexible outer layer that is pressed against a more radially stiff inner layer. FIGS. 2A-2B show an example of a cross-section of a stiffening member of an apparatus (e.g., device, system) that has been stiffened by application of a vacuum. FIG. 2B shows a close-up of the arrangement of layers of FIG. 2A in a non-rigid form. In this example, the stiffening member includes an innermost layer 115 configured to provide an inner surface against which the remaining layers can be consolidated (e.g., when a vacuum is applied). The innermost layer 115 can include a reinforcing element or coil. In particular, the innermost layer 115 can be configured as an ICWT, including ICWTs as described herein, formed, for example, from an outer wound wire (e.g., cable, ribbon, wire, etc.) continuous with an inner wound wire disposed on either side of a layer or tube (e.g., a sealing layer). The stiffening member can also include a slip layer 113 on (e.g., radially outward of) the innermost layer. The slip layer can be, for example, a lubricant, coating, and / or powder (e.g., talcum powder) located on the outer surface of the inner layer 115 and / or in the gap layer 111. The radial gap layer 111 can separate the slip layer 113 from the braided or woven layer 109 (referred to herein for convenience as the "braided layer") to provide a space between the braided layer and the slip layer, for example, when no vacuum is applied, through which the braided layer can move, and this space or gap can be removed when a vacuum is applied to allow the braided or woven layer to move radially inward when the vacuum is applied. A second gap layer 107 may be present between the braid layer 109 and may be similar to layer 111 .As described in connection with Figures 3C-3F, multiple braid layers may be included (e.g., two, three, four, or more braid layers may be included) and may be separated by additional gap and / or slip layers. The outermost layer 101 may be separated from the braid layers by a gap layer and may be configured to move radially inward and conform to the surface of the braid layers when a vacuum is applied to pull down against the braid layers. The outermost layer 101 may be soft, atraumatic, and may be sealed at both ends to form a vacuum-tight chamber with the innermost layer 115. The outermost layer 101 may be made of an elastomer, for example, urethane. The hardness of the outermost layer 101 may be, for example, 30A to 80A. Additionally, the outermost layer 101 can have a thickness of between 0.0001 inch and 0.01 inch, such as about 0.001 inch, 0.002 inch, 0.003 inch, or 0.004 inch. Alternatively, the outermost layer can be a plastic, including, for example, LDPE, nylon, or PEEK.

[0073]

[0100] Any of these devices can include multiple braid layers, and the device can include a tube having a wall formed from multiple layers disposed about a lumen 120 (e.g., for placement of an instrument or endoscope therethrough). A vacuum can be applied between the layers to provide stiffness to the stiffening device 100. Alternatively, any of the tubular devices described herein can include a solid core forming the inner layer 115.

[0074]

[0101] The innermost layer 115 can be configured to provide an inner surface against which the remaining layers can be compacted, for example, when a vacuum is applied within the wall of the stiffening device 100. This structure can be configured to minimize bending forces and / or maximize flexibility in a non-vacuum state. As mentioned above, the innermost layer 115 can be an ICWT, which can include reinforcing elements 150z or coils within a matrix (e.g., a cling layer in some examples), as described in more detail below.

[0075]

[0102] Layer 109 may be a first braided layer including braided yarns 133 similar to those described elsewhere herein. The braided layer may be, for example, 0.001 inch to 0.040 inch thick. For example, the braided layer may be 0.001 inch, 0.003 inch, 0.005 inch, 0.010 inch, 0.015 inch, 0.020 inch, 0.025 inch, or 0.030 inch thick. In some embodiments, the braid may have tensile or hoop fibers 137. The hoop fibers 137 can be spiraled and / or woven into a braided layer, and can be arranged in 2-50, e.g., 20-40, hoops per inch. In some embodiments, the stiffening devices described herein can have more than one braided layer. For example, the stiffening devices can include two, three, or four braided layers.

[0076]

[0103] In some embodiments, the outermost layer 101 may include a lubricant, coating, and / or powder (e.g., talcum powder) on its outer surface to enhance sliding of the stiffening device through the anatomy. The coating may be hydrophilic (e.g., Hydromer® coating or Surmodics® coating) or hydrophobic (e.g., fluoropolymer). The coating may be applied, for example, by dipping, swabbing, painting, or spraying the coating on. The innermost layer 115 may likewise include a lubricant, coating (e.g., hydrophilic or hydrophobic coating), and / or powder (e.g., talcum powder) on its inner surface to maximize flexibility, particularly configured to allow boundary layers to more easily shear against each other when no vacuum is applied to the stiffening device 100.

[0077]

[0104] A vacuum can be maintained within the stiffening device 100 from a minimum to a full atmospheric vacuum (e.g., about 14.7 psi). Some embodiments can include a bleed valve, regulator, or pump control so that the vacuum can be released to any intermediate level to provide variable stiffness capabilities. This vacuum pressure can be advantageously used to stiffen the stiffening device structure by compressing the layers of the braided sleeve against adjacent layers. The braid can naturally bend when bending (i.e., when bending perpendicular to its longitudinal axis), and as the sleeve is bent, the lattice structure formed by the interwoven strands deforms so that the braid rests on the inner layer and follows the bent shape. This results in a lattice geometry in which the corner angles of each lattice element change as the braided sleeve bends. When compressed between conformal materials such as the layers described herein, the lattice elements are fixed at their current corners and have an enhanced ability to resist deformation upon application of a vacuum, thereby stiffening the entire structure in bending when a vacuum is applied. Also, in some embodiments, the hoop fibers in or on the braid can support tensile loads that help prevent local buckling of the braid at high applied bending loads. The stiffness of the stiffening device 100 can increase from 2 to more than 30 times, such as 10, 15, or 20, or 50, or 100 times, when transitioning from the soft to the stiff configuration. In some embodiments of the vacuum stiffening device 100, there may be only one braid layer. Other embodiments of the vacuum stiffening device 100 may include two, three, or more braid layers. In some embodiments, one or more of the radial gap layers or slip layers of the stiffening device 100 can be eliminated. In some embodiments, some or all of the slip layers of the stiffening device 100 can be eliminated.

[0078]

[0105] The braid layer described herein can act as a variable stiffness layer. The variable stiffness layer can include one or more variable stiffness elements or structures that, when actuated (e.g., when a vacuum is applied), increase bending stiffness and / or shear resistance, resulting in higher stiffness. Other variable stiffness elements can be used in addition to or instead of the braid layer. In some examples, an engagement portion can be used as a variable stiffness element, as described in International Patent Application No. PCT / US2018 / 042946, filed July 19, 2018, entitled "DYNAMICALLY RIGIDIZING OVERTUBE," which is incorporated herein by reference in its entirety. Alternatively or additionally, the variable stiffness element can include particles or granules, jamming layers, flakes, stiffening shaft members, stiffening pieces, longitudinal members or substantially longitudinal members.

[0079]

[0106] The stiffening devices described herein can also be stiffened by application of positive pressure rather than vacuum. For example, with reference to Figures 3A-3B, a stiffening device (e.g., device or system) 2100 can be similar to the stiffening device 100 described above, except that it can be configured to hold pressure (e.g., greater than 1 atmosphere) rather than a vacuum for stiffening. The pressure-activated stiffening device 2100 can also include multiple layers disposed about a lumen 2120 (e.g., for placement of an instrument or endoscope therethrough).

[0080]

[0107] For example, Figures 3A-3B show longitudinal and radial cross sections of one embodiment of a pressure-activated stiffening member of a stiffening apparatus. The stiffening device 2100 shown in Figures 3A and 3B can include an innermost layer 2115 (similar to innermost layer 115), which can be an inner coiled tube, as described above and in more detail below. The stiffening device 2100 can also include a slip layer 2113 (similar to slip layer 113), a pressure gap 2112, a bladder layer 2121, a gap layer 2111 (similar to gap layer 111), a braid layer 2109 (similar to braid layer 109) or other variable stiffness layer described herein, a gap layer 2107 (similar to layer 107), and an outermost containment layer 2101. In any of these devices, the gap region (e.g., pressure gap, gap layer, etc.) can have a variable gap distance or can have a constant gap distance. For example, a device with a tapered OCWT diameter can have a tapered gap, such that one end of the device can have a larger gap than the other end of the device, thereby forming a gap region. In the soft state, the end with the larger gap can be made softer than the end with the smaller gap. This can provide variable stiffness along the length of the device in the soft state. A variable stiffness catheter can be advantageous for trackability, and using a variable gap distance (without affecting the stiffness state) can be an efficient and effective way to achieve variable stiffness in the soft state.

[0081]

[0108] The pressure void 2112 can be a sealed chamber that provides a void for the application of pressure to the layers of the stiffening device 2100. Pressure can be supplied to the pressure void 2112 using a fluid or gas expansion / pressure medium. The expansion / pressure medium can be water or saline, or a lubricating fluid, such as oil or glycerin. The lubricating fluid can, for example, facilitate the layers of the stiffening device 2100 moving over each other in the soft configuration. The expansion / pressure medium can be supplied to the void 2112 upon stiffening of the stiffening device 2100, and can be partially or completely evacuated to transform the stiffening device 2100 back to the soft configuration. In some embodiments, the pressure void 2112 of the stiffening device 2100 can be connected to a pre-filled pressure source, such as a pre-filled syringe or a pre-filled inhaler, thereby reducing preparation time required by the physician.

[0082]

[0109] Bladder layer (or "bladder") 2121 may be made of, for example, a low durometer elastomer (e.g., shore hardness 20A to 70A) or a thin plastic sheet. Bladder layer 2121 may be formed from a thin sheet of plastic or rubber sealed lengthwise to form a tube. The lengthwise seal may be, for example, a butt joint or a lap joint. For example, a lap joint may be formed lengthwise in a rubber sheet by melting the rubber at the lap joint or by using an adhesive. In some embodiments, bladder layer 2121 may be 0.0002 inches to 0.020 inches thick, such as about 0.005 inches thick. Bladder layer 2121 may be soft, high friction, stretchy, and / or wrinkle-resistant. In some embodiments, bladder layer 2121 is polyolefin or PET. The bladder 2121 can be formed, for example, using methods used to form heat shrink tubing, such as extrusion of a substrate, followed by wall thinning by heat, pressure and / or radiation. When pressure is provided through the pressure void 2112, the bladder layer 2121 can expand through the void layer 2111 to press the braid layer 2109 against the confining outermost layer 2101 such that relative motion of the braided yarns is reduced. Any of the devices described herein can include multiple filling points for the bladder and / or distally located filling points for the bladder layer. Any of the devices described herein can include a bladder configured to prevent adhesion, e.g., adhesion in a closed configuration, as described in more detail below.

[0083]

[0110] The outermost containment layer 2101 can be a tube, such as an extruded tube. Alternatively, the outermost containment layer 2101 can be a tube with a reinforcing member (e.g., a metal wire with a circular or rectangular cross section) encapsulated in an elastomeric matrix, similar to those described in connection with the innermost layer of other embodiments described herein. In some embodiments, the outermost containment layer 2101 can include a helical spring (e.g., made of round or flat wire) and / or a tubular braid (e.g., made of round or flat metal wire) and a thin elastomeric sheet that is not bonded to other elements in the layer. The outermost containment layer 2101 can be a tubular structure with a continuous smooth surface. This can favor an outer member that slides against it with a close and locally high contact load (e.g., a nesting configuration as described further herein). The outer layer 2101 can also be configured to support a compressive load, such as pinching. Additionally, the outer layer 2101 (eg, with the reinforcing elements therein) can be configured to prevent the stiffening device 2100 from changing diameter when pressure is applied.

[0084]

[0111] Both the outer layer 2101 and the inner layer 2115 (e.g., ICWT) can include reinforcing elements therein, so that the braid layer 2109 can be moderately inhibited from both shrinking in diameter (under tensile load) and increasing in diameter (under compressive load).

[0085]

[0112] By using pressure rather than vacuum for transition from the soft to the rigid state, the stiffness of the stiffness imparting device 2100 can be increased. For example, in some embodiments, the pressure supplied to the pressure void 2112 can be between 1 and 40 atmospheres, such as between 2 and 40 atmospheres, between 4 and 20 atmospheres, between 5 and 10 atmospheres. In some embodiments, the pressure supplied is about 2 atmospheres, about 4 atmospheres, about 5 atmospheres, about 10 atmospheres, about 20 atmospheres. In some embodiments, the stiffness imparting device 2100 can exhibit a change in relative bending stiffness from the soft to the rigid configuration (as measured in a simple cantilever configuration) of 2 to 100 times, such as 10 times to 80 times, 20 times to 50 times. For example, the stiffness imparting device 2100 can have a change in relative bending stiffness from the soft to the rigid configuration of about 10 times, 15 times, 20 times, or 25 times, 30 times, 40 times, 50 times, or more than 100 times.

[0086] Internal Coil Wound Tubing (ICWT)

[0113] Generally, stiffening devices are described herein that may include an inner coil wound tube (ICWT) as the innermost layer 115, which may include a reinforcing element such as a coil. The ICWT may be configured to be very flexible, and thus, for example, easily bend with very little force, while providing a large diameter opening (lumen), having very high compressive strength, and preventing collapse under externally applied (e.g., inward) pressure. The inner diameter of the lumen may be 2 mm or more, 3 mm or more, 4 mm or more, 5 mm or more, 6 mm or more, 7 mm or more, 8 mm or more, 9 mm or more, 10 mm or more, 11 mm or more, 12 mm or more, 14 mm or more, 15 mm or more, 20 mm or more, 25 mm or more, 30 mm or more, 35 mm or more, 40 mm or more, 45 mm or more, 50 mm or more, 55 mm or more, 60 mm or more, 65 mm or more, 70 mm or more, 75 mm or more, etc.

[0087]

[0114] Generally, the ICWTs described herein are thin-walled structures, which can increase flexibility while decreasing the weight of the ICWT. For example, the wall thickness can be about 2 mm or less, about 1.75 mm or less, about 1.5 mm or less, about 1.25 mm or less, about 1.0 mm or less, about 0.9 mm or less, about 0.8 mm or less, about 0.7 mm or less, about 0.6 mm or less, about 0.5 mm or less, about 0.25 mm or less, etc.

[0088]

[0115] The ICWT may be a wire-reinforced tube (or may be formed from a tubular extrusion or a sheet or strip of material that is spirally wound to provide a wire-reinforced tube). The wire-reinforced tube may include a matrix, which may be an inner layer or tube formed from a polymeric material. The matrix may be disposed between the inner and outer wires. The term "wire" in the context of an ICWT may refer to any elongated support member, such as a cable, ribbon, filament, etc., that may be wrapped around the interior and exterior of a tubular ICWT. In some embodiments, the wire of the ICWT is a substantially flat, ribbon-like wire, having a width greater than a thickness and at least two faces that are substantially parallel. The edges may be squared, rounded, chamfered, etc.

[0089]

[0116] Thus, the ICWT may include a very soft intermediate matrix, the exterior of which is wrapped by a coil (e.g., a helical coil) of wire (e.g., a ribbon). The inner and / or outer surfaces of the ICWT may also be covered and / or laminated with a soft polymer material. In some cases, this soft polymer coating material may be a hydrolytically stable elastomeric material, and therefore does not soften or change when exposed to a fluid, e.g., water. Any of these ICWTs may include one or more coatings on the inner and / or outer surfaces of the ICWT. For example, the ICWT may include a lubricious coating or material (e.g., a soft polymer material) and may be formed from a material that is, or can be coated with, a lubricious and / or hydrophobic and / or fluid-resistant material.

[0090]

[0117] In particular, described herein are devices in which the inner and outer wire coils are formed as a single continuous wire that extends around both the outside periphery of the matrix having a first pitch and the inside periphery of the matrix having a second pitch, and the pitch angle of the outer wire may be the same as or different from the pitch angle of the inner wire.

[0091]

[0118] For example, FIG. 4A shows a schematic cross-sectional view of one embodiment of an ICWT that can be used with any of the devices described herein. In this embodiment, the ICWT 415 includes a matrix 465, the outside of which is wrapped with a first coil portion 450 formed from a flat ribbon-like wire, and the inside of which is wrapped with a second coil portion 450', also a flat ribbon-like wire. As described in more detail below, the first coil portion and the second coil portion can be continuous and / or formed from the same wire. The walls of the ICWT can be thin, for example, having a thickness 470 of 1 mm or less (e.g., 0.5 mm or less, 0.3 mm or less, 0.1 mm or less, etc.). The outer surface can be covered or coated with a polymer material 467, which can be an elastomeric material and can be bonded (e.g., melted, fused, etc.) over the first coil and the matrix. Alternatively or additionally, the inner surface may be covered or coated with a polymeric material 467', which may be the same or a different elastomeric material, and may be bonded (e.g., melted, fused, etc.) onto the second coil portion and matrix as shown. The outer polymeric material 467 and / or the inner polymeric material 467' may be the same material as the intermediate matrix 465, or may be a different material. In some embodiments, the outer and / or inner polymeric material may be referred to as an outer matrix material (as opposed to an intermediate matrix material between the inner reinforcing member 450 and the outer reinforcing member 450', e.g., a coil, wire, etc.).

[0092]

[0119] In FIG. 4A, the dimensions of the ICWT are not shown to scale because the inner diameter 469 can be much larger relative to the wall thickness 470.

[0093]

[0120] Thus, in any of the ICWTs described herein, the ICWT 415 may include wires 450 (which may be more generally referred to as reinforcing elements) that are wound both inside and outside the matrix 465 of the ICWT. In ICWT embodiments in which the inner and outer reinforcing elements (wires) are separate, the distal ends of the reinforcing elements may be loose, as shown in FIG. 4B. However, loose reinforcing elements (wires) may cause significant problems, particularly for medical applications, as the loose ends may come undone from the device and, when inserted into the body, may cause obstruction or damage to surrounding tissues due to the protruding sharp tips. To reduce these risks, in some embodiments, it is particularly advantageous to form the reinforcing elements (wires) that form the inner and outer coils from one continuous piece that extends between the proximal and distal ends of the matrix 465. For example, the reinforcing elements 450 may start at the proximal end of the ICWT, extend to the distal end of the ICWT, and then fold back, as shown in FIG. 4C. This configuration eliminates the termination of the wires at the distal end of the ICWT that forms the innermost layer of the stiffening device.

[0094]

[0121] FIG. 4B shows an example of only the reinforcing elements (e.g., wires) forming the inner and outer coils of the ICWT, the inner and outer coils being separate wires. In this example, the outer wire coil 450 includes a wire that is spiraled (helically) on or around a matrix (not shown) and on the inner reinforcing element (e.g., wire) 450'. The reinforcing element 450 in FIG. 4B starts at the proximal end, spirals helically toward the distal end of the ICWT, and terminates at a first end 454. Similarly, the inner reinforcing element 450' spirals in the outer reinforcing layer (not shown, but inside the matrix) and terminates at 454' at the distal end of the ICWT. This configuration results in loose ends 454, 454' of the wire at the distal end of the ICWT. These loose ends can sometimes protrude and cause manufacturing problems and injury to the patient. Typically the wire ends can also bend inwards (not shown), which can also be problematic and potentially affect the function of the stiffening device or capture of devices passed through the center.

[0095]

[0122] FIG. 4C shows an example of a reinforcing element 450 (e.g., wire) of an ICWT, where the inner and outer helical coils reinforcing the device are formed from a single continuous length of wire, which starts at the proximal end of the ICWT 415 and extends toward the distal end of the ICWT, where the reinforcing wire is folded back toward the proximal end of the ICWT. This continuous winding configuration avoids exposing, e.g., cutting, the end of the reinforcing wire at the distal end of the ICWT 415. Although a helical configuration is shown in FIG. 4C, it will be understood that other configurations having a continuous structure extending from the proximal portion (e.g., proximal end) of the innermost layer to the distal end and back to the proximal portion (e.g., proximal end) of the innermost layer also result in the absence of wire ends at the distal end of the layers and are contemplated herein. In FIG. 4C, the inner and outer lengths of wire forming the inner coil 450′ and outer coil 450 are shown joined (e.g., bonded, fused, etc.) at 453. Alternatively, the inner and outer wires can simply be formed from the same wire.

[0096]

[0123] In any of the devices described herein, the inner and outer coil regions of the reinforcing coil (e.g., wire, ribbon, etc.) can have a uniform pitch or a non-uniform pitch. The pitch of the inner coil region can be the same as the pitch of the outer coil region, or the two can be different. In any of the devices described herein, the inner and outer coil regions of the reinforcing element can have a uniform helix angle or a non-uniform helix angle. The helix angle of the inner coil region can be the same as or different from the helix angle of the outer coil region. As used herein, helix angle can refer to the angle between any helix and an axial line through that helix. For example, Figures 5A-5C show examples of inner and outer coil regions of a reinforcing wire or ribbon.

[0097]

[0124] In FIG. 5A, one embodiment of a reinforcing coil has an outer helical coil region 550 and an inner helical coil region 550'. In this embodiment, the outer and inner helical coil regions can be formed from the same continuous ribbon that is folded over as described above. An axial line 532 is shown passing through the midline of the device. In FIG. 5A, the inner coil region 550' and the outer coil region 550 each form opposite (e.g., +α and -α) but constant helical angles. An inner layer 575 is also shown. In some embodiments, a matrix layer (not shown) can be disposed between the inner coil region and the outer coil region.

[0098]

[0125] 5A and 5B show the same device rotated 90 degrees around the long axis (axial line 532). These figures show helix angles with opposite but equal angles. Because the helix angles are equal to each other, they cross repeatably along the length, creating the "spine" seen in FIG. 5B and the aperture (seen in FIG. 5A). Bending in the direction of the spine is less flexible than the aperture. In some embodiments, it may be beneficial to have equal bending stiffness regardless of orientation. Thus, in some embodiments, it may be beneficial to have helix angles of different magnitudes, as shown in FIG. 5C. In FIG. 5C, the helix angle (α) of the outer coil region 550 is not equal to the helix angle (β) of the inner coil region 550', and therefore the intersecting gap region of the inner and outer coil regions is not aligned along the long axis.

[0099] Bladder Layer

[0126] Any of the devices described herein can include a bladder layer configured to prevent or reduce adhesion of the bladder layer to itself or to the ICWT. For example, FIG. 6 shows a cross-section of a stiffening device (similar to that shown in FIGS. 3A-3B) including a bladder layer 2121 adjacent to the ICWT forming the innermost layer 2115 and separated by a gap 2112 and a slip layer 2113. The bladder layer 2121 can include one or more features configured to prevent the bladder from adhering to itself or to the innermost layer 2115. If the bladder layer 2121 adheres to itself or to the innermost layer 2115, the bladder cannot expand or cannot expand properly and may fail. To prevent this from occurring, one or more additives can be added to the bladder layer 2121. For example, a slip additive, a lubricant, or a color additive (e.g., TiO) can be added to the bladder layer 2121.

[0100]

[0127] In some embodiments, the bladder layer can be textured to prevent sticking. For example, the bladder layer can have ribs, speckles, can include protrusions, etc. This texturing can help to prevent sticking of the bladder by creating space between the layers on either side of the bladder and between the bladder layer and the surrounding layers. This space can also provide expansion channels through which air (or other expansion material) can be forced out.

[0101]

[0128] In some embodiments, the outer surface of the innermost layer 2115 can be textured (e.g., ribbed, speckled, includes protrusions, etc.). Texturing can be accomplished by wrapping a textured film or braid around layer 2115 and firing, then removing the film to impart texture to the innermost layer 2115. In some embodiments, texturing is accomplished by placing the innermost layer 2115 (and / or bladder layer 2121) in a textured mold and applying heat and / or pressure. Other methods are contemplated.

[0102]

[0129] In some embodiments, a braided layer can be added between the innermost layer 2115 and the bladder layer 2121. This layer can separate the innermost layer 2115 and the bladder 2121 and prevent them from adhering together. The textured nature of the braided layer can also help prevent the braided layer from adhering to surrounding layers.

[0103]

[0130] In some embodiments, inner layer 2115 and / or bladder 2121 can include a coating (eg, parylene) to help prevent adhesion.

[0104]

[0131] In some embodiments, one or more tubes or channels can be disposed between the bladder 2121 and the inner layer 2115 and extend along at least a portion or the entire length to ensure that a fluid path exists to inflate the bladder.

[0105] Preventing or reducing delamination

[0132] In composite structures such as the stiffening tubes described herein, layer adhesion is important. Delamination represents a failure of the structure and can lead to clinical complications. Enhanced interlayer adhesion is needed. Some of the materials used in the layers of these structures can provide suitable properties for their function (e.g., in the stiffening tubes) but are less suitable for interlayer adhesion. Some of the layers forming the devices described herein can include one or more adhesion layers, which can create a bondable (e.g., melt-bondable or adhesively bonded) surface that improves adhesion to the catheter jacket after the reflow process.

[0106]

[0133] In some embodiments, the adhesion layer creates enhanced interlayer adhesion. The adhesion layer can be disposed between layers of a composite tubular structure (e.g., on the opposite side of a reinforcement). For example, the adhesion layer can be included as part of an inner coil wound tube (ICWT) and / or an outer coil wound tube (OCWT). The bond between the adhesion layer and the surrounding layers (e.g., reinforcing layers) can prevent delamination of the ICWT and / or OCWT layers. For example, the adhesion layer can prevent delamination across the reinforcing layers by requiring a much higher force to pull its adhesive counterpart across the reinforcing elements.

[0107]

[0134] 7A shows a cross-sectional view of one embodiment of a stiffening member including an inner coiled tube with a sealing layer. In FIG. 7A, the device includes an inner layer 775, a coiled layer 750, and a sealing layer 776. The inner layer 775 is not bonded to the inner coiled layer 750, but the sealing layer 776 can be bonded to an intermediate layer 780 (e.g., a matrix layer), and the inner layer 775 can be bonded to the sealing layer 776. Similarly, the outer layer 777 can be bonded to the intermediate layer 780, but not to the outer coiled layer 760.

[0108]

[0135] 7B and 7C show examples of an outer coiled tubing layer (OCWT) of the outer layer 710 and an inner coiled tubing layer (ICWT) of the inner layer 715 of a composite tube structure that can be part of a stiffening device. In general, an ICWT can be a similar structure to an OCWT (including using a single metal coil to form both the inner and outer coils). These examples show a sealing layer 774 that can be disposed between the surrounding layers. FIG. 7B shows the inner longitudinal axis 735 of the OCWT. Layer 775 is the inner surface of the inner layer of the OCWT 710. Layer 774 is the sealing layer. Layer 750 is a reinforcing element (e.g., a wire wound around the matrix layer 774). Layer 776 is the outer surface of the OCWT 715. FIG. 7C is similar to that shown in FIG. 7B, but for an ICWT. In this example, similar to the ICWT schematic shown in Figure 4A, the ICWT includes an outer coil 750 and an inner coil 750', which may be formed from the same wire that is folded over the distal end of the device (not shown). Outer and / or inner layers 776, 775 may be included.

[0109] Methods and techniques for adjusting stiffness

[0136] In some embodiments of the devices described herein, the layers of the stiffening device terminate at different points along the length of the device. In the case of a dynamically stiffening catheter, multiple layers can serve to create a stiffer tip than desired. Axial separation of the distal ends of the layers can enhance flexibility of the distal tip. Enhanced flexibility of the distal tip can enhance tracking of the distal tip.

[0110]

[0137] For example, in a stiffening device comprising an innermost layer 815, a bladder layer 821, a braided layer 809, and an outermost confinement layer 801, a distal end of the innermost layer 815 can be separated by a first gap 8102 from the braided layer 809, the bladder layer 821, and the outermost layer 801, as shown in Figures 8A and 8B.

[0111]

[0138] In Figure 8A, the first difference 8102 is larger than in Figure 8B. Thus, the distal tip section 833 is longer in Figure 8B than in Figure 8A. This longer first difference 8102 results in a softer distal tip for the stiffening device shown in Figure 8A.

[0112]

[0139] Figure 8C shows a graph of stiffening device stiffness versus length for both the device of Figure 8A (4A) and the device of Figure 8B (4B). As shown, the stiffness of the embodiments is different, with Figure 8A beginning with a longer distal tip section 833, and the embodiment having a region of lower distal stiffness compared to the embodiment of Figure 8B.

[0113]

[0140] In some embodiments, additional differences between layers can be provided. For example, a first difference can be provided between the inner layer and the bladder layer distal end, and a second difference can be provided between the bladder layer, the braid layer, and the outer layer distal end. In some embodiments, a first difference can be provided between the inner layer and the bladder layer distal end, a second difference can be provided between the bladder layer and the braid layer distal end, and a third difference can be provided between the braid layer and the outer layer distal end. Other permutations and combinations of differences between the layer distal ends are also contemplated.

[0114]

[0141] Any of the difference distances can be about 0.1 mm to 5 cm, 0.5 mm to 4 cm, 1 mm to 3 cm, 1 mm to 1 cm, etc.

[0115]

[0142] In embodiments where more than one gap separates the distal ends of the layers, these gaps may be the same or different.

[0116] Distal end expansion / contraction

[0143] In some embodiments, the stiffening devices disclosed herein include a dedicated lumen extending to the distal end that allows the device to expand / stiffen from distal to proximal instead of proximal to distal. For long length catheters with narrow walls and closely adjacent components that may have a tendency to adhere or separate poorly, there may be a risk of insufficient expansion to provide stiffening all the way to the distal end.

[0117]

[0144] The dedicated lumens may comprise lumens below or above the bladder layer. Other radial and axial termination points are also contemplated.

[0118]

[0145] In some embodiments, the lumen comprises a thin-walled flat tube, although other lumen configurations (eg, round tubes) are possible.

[0119]

[0146] The lumen can include a material such as PET. Other materials are possible (e.g., TPU, TPE, PEEK, Mylar, urethane, or silicone).

[0120]

[0147] In some embodiments, the lumen wall comprises a thickness of about 0.0005 inches, 0.0001 inches to 0.001 inches, 0.00001 inches to 0.001 inches, etc.

[0121]

[0148] In some embodiments, the lumen comprises a thin walled flat tube comprising PET heat shrink tubing approximately 0.0013 cm (0.0005 inch) thick.

[0122]

[0149] In some embodiments, the lumen contains a breather (e.g., breather mechanism) material inside it that acts to prevent face-to-face surface sealing during application of vacuum to remain open during application of vacuum. The device can include a one-way valve located in the handle that does not allow application of fluid pressure but does allow application of vacuum. These mechanisms can be useful because thin heat shrink can collapse in vacuum and seal itself.

[0123]

[0150] 9 shows a cross-sectional view of one embodiment of a stiffening device having a longitudinal axis 935 with a distal inflation lumen 976x extending between an inner layer 915 and a bladder layer 921. A braid layer 909 is disposed over the bladder layer 921, and an outer layer 901 is disposed over the braid layer. It will be understood that this view does not show any intervening gaps or slip layers.

[0124] Stabilized treatment base

[0151] In some embodiments, the stiffening devices described herein can be used to establish a stable, imageable base for performing procedures, particularly those performed deep within the body (e.g., within the pulmonary vasculature). In such procedures, determining the exact location of the tip of the device can be a challenge. Loss of sight is common, which can increase procedure times, delay treatment, necessitate increased use of contrast agents and radiation, and can pose substantial risks to the procedure and the patient.

[0125]

[0152] The use of dynamic stiffening allows for the creation of "deeply stable" points that serve as important landmarks for enhanced navigation and treatment. Having a dynamic stiffening device as a stable reference point for navigation and treatment is very helpful. Currently available devices such as coronary pigtail catheters would not provide a stable point. When a dynamic stiffening catheter is advanced and then stiffened, its tip can serve as a fiducial marker for use with imaging, e.g., angiography, synthetic fluoroscopy, CT, DynaCT, ultrasound, etc. Machine learning and artificial intelligence can use this reference to guide further interventions. In particular, stiffening the entire length of the device can create a particularly stable distal point.

[0126]

[0153] In an exemplary embodiment, as shown in FIG. 10, imaging guidance can be used to navigate a dynamic stiffening catheter 1000 through the body (e.g., vasculature) to a deep treatment site (e.g., pulmonary vasculature). At that point, the device can be stiffened. A dilator 1077 is located in the central lumen of the dynamic stiffening catheter and emerges from its distal end. Once the dynamic stiffening catheter is withdrawn, treatment can be performed in the surrounding anatomy, either directly through its lumen or via introduction of other devices therethrough. A stable and easily imageable distal tip 1055 is shown. Additionally, the distal tip as a reference can be clinically valuable since subsequent treatment elements can be mathematically calculated and planned.

[0127] Particulate-containing stiffening device

[0154] In some embodiments, the dynamic stiffening catheters described herein include particles against which the bladder is compressed. Examples of particles can include, for example, but are not limited to, particulates or powders including organic materials (e.g., sand (mineral or rock)), plastics, elastomers, or metals.

[0128]

[0155] 11 shows an example of a portion of a catheter having particles compressed with a braid layer 1109. The catheter includes an inner layer 1115, a bladder layer 1121, a layer having a combination of braid 1109 and particles 1178x, and an outer layer 1101.

[0129]

[0156] In some embodiments, the bladder can be compressed against the particles only, as shown in cross section in Figure 12. The embodiment shown in Figure 12 includes inner layer 1215, bladder layer 1221, particle layer 1278, and outer layer 1201.

[0130]

[0157] By varying the use of powder and braids along the length of the catheter, it is possible to vary stiffness along the length of the catheter. For example, it is possible to create a significantly softer tip by eliminating the braids from the end of the compressed section and replacing it with powder. Alternatively, if extreme stiffening is required in a particular section, that section can contain both braids and powder when compressed.

[0131]

[0158] In some embodiments, as shown in Figure 13, a portion of the catheter may include only the braid 1309 and a portion may include only the particles 1378 against which the bladder 1321 may be compressed. Also shown in Figure 13 is the longitudinal axis 1335 of the device as well as the inner layer 1315 and the outer layer 1301.

[0132]

[0159] In some embodiments, as shown in Figure 14, a portion of the catheter includes only braids 1409 and a portion includes braids 1409 and particles 1478. Also shown in Figure 14 is the longitudinal axis 1435 of the device as well as the inner layer 1415 and the outer layer 1401.

[0133]

[0160] Other configurations are possible, for example in some embodiments one portion of the catheter may comprise only braids, one portion may comprise only particles, and one portion may comprise a combination of braids and particles against which the bladder may be compressed.

[0134]

[0161] In some embodiments, those portions of the catheter that include particles (particles only or with braids) can include different amounts or compositions of particles. The tightly packed particles can include particles, particulates, or powders, including but not limited to organic materials (e.g., sand (mineral or rock)), plastics, elastomers, or metals. Varying the powder properties, such as size (1 micron, 10 microns, 100 microns, 1000 microns), shape, porosity, etc., allows for different degrees of stiffening.

[0135]

[0162] By filling the space, the bladder can be compressed (using vacuum or pressure) with particles in addition to the braid to create a stiffening catheter with increased stiffness.

[0136] Variable pitch coiled tubing

[0163] The stiffening devices described herein can be configured to prevent breakage or fracture at the distal and / or proximal ends of the stiffening devices. The stiffening devices described herein can be configured to enhance compliance and result in ends with highly engineered stiffness transition profiles. As described above, the stiffening devices can include multiple layers, including a stiffening layer (e.g., a variable stiffness layer), a bladder layer that can be pressed against the variable stiffness layer to increase the stiffness of the variable stiffness layer and thus the stiffness of the device, and one or more reinforcing layers, such as an inner coiled wound tube (ICWT) and an outer coiled wound tube (OCWT). In a non-rigidified state, these devices can be very soft, and it can be advantageous to have a relatively smooth and compact profile, especially the distal end region of these devices. Such devices can be particularly beneficial when engaged (e.g., nested or telescopic) with other devices. The distal end can be designed to be a non-rigid section with stiffening elements (e.g., bladders and stiffening layers) terminating proximally, thus enhancing the gradual increase in stiffness from the non-rigidified distal tip to the more proximal stiffened section.

[0137]

[0164] For example, it can be useful to control the stiffness of the distal end of the stiffening device to allow for a smooth, continuous transition across regions of different stiffness, including when sliding over one another, particularly in nested systems. Thus, in any of the devices described herein, the stiffening device can include a distal end region that is configured to be softer than a more proximal region, even when the device is stiffened (or in some cases because that section is non-rigid). In some embodiments, this can be achieved by including a variable pitch in one or more coiled tubes (e.g., ICWT, OCWT) within the stiffening device.

[0138]

[0165] For example, Figures 15A-15D show two examples of coiled tubing that can be included as part of a stiffening device. In Figure 15A, the distal end region of coiled tubing 1500 is shown partially transparent. This example includes a proximal region 1537 having both a first, upper coil helically wound around the tube with a first pitch and a second, lower coil that can be wound adjacent to it in the opposite direction. Either the upper or lower coil can extend into the distal end region 1536 of the device or is only one of the stiffeners. Alternatively or additionally, the portion of coil 1539 that extends distally in the distal region (upper or lower) can have an increased or increasing pitch as shown in Figures 15A-15D, and in these examples, the coil 1539 with the continuously increasing pitch that extends distally in the distal region is the lower coil. 15A-15B, an exemplary coiled tube is shown adjacent to or surrounded by a variable stiffness layer (e.g., knitted, woven, braided, etc.) 1537 that extends toward the distal end of the stiffening device. FIGS. 15C-15D show an example of a coiled tube 1500' without the variable stiffness layer, exposing the coiled layer that forms a tube of polymeric material through which the coiled coil extends. In general, one or more coils of the coiled tube can have a variable pitch in the unpressurized distal end region of the device. This can reduce the bending stiffness of the distal end region along with reducing the number of wires and eliminating the stiffening element in that section.

[0139]

[0166] Any of the stiffening apparatuses including stiffening devices / stiffening members described herein can include an inner coiled tube and / or an outer coiled tube configured as a variable pitch coiled tube. This mechanism can provide a tip that transitions between devices having different stiffness (e.g., between rigid and non-rigid configurations) without damaging the device or causing it to get stuck or become jammed.

[0140]

[0167] For example, described herein is a stiffening device that includes an inner coiled tube, an outer coiled tube, a variable stiffness layer, and a bladder layer. The bladder layer is configured to engage the variable stiffness layer to change the stiffness of the device based on an applied pressure (e.g., positive pressure or, in some embodiments, negative pressure). For example, the bladder layer can be configured such that when pressurized by positive or negative pressure, the bladder layer presses against the variable stiffness layer. In general, the inner coil in either or both of the inner and outer coiled layers can be configured such that across the distal end region of the unstiffened stiffening device (e.g., the most distal 0.5 cm, 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, etc., or more), the coil extends as a single member that helically winds around the distal end region and at an increasing pitch from that pitch across the stiffening region. In some embodiments, the pitch can increase continuously. In some embodiments, the device includes only an inner coiled member (ICW) having two layers of coils, where a distal end region in the upper coil or lower coil can extend distally with an increased or increasing pitch, and the other coil (e.g., the lower coil or upper coil) stops proximal to the distal end region.

[0141] Reflowed Distal Tip

[0168] Any of the stiffening devices (or stiffening members that may be part of the stiffening apparatus) may include a tip configured as a cap or seal around the stiffening device and / or between layers forming the stiffening device. FIG. 16A shows an example of a cross-section of a portion of a distal end portion of a stiffening device including an inner coiled tube 1617 (ICWT), which may be any of the coiled tubes described herein, and an outer coiled tube 1615 (OCWT). In this example, other layers (e.g., bladder layer, variable stiffness layer, etc.) are not shown, but may be included. In FIG. 16, the cross-section shows a cross-sectional view of only the top of the tubular stiffening device as indicated by the axial midline 1623. In FIG. 16A, an annular tip 1619 (e.g., cap, ring, etc.) is attached over and extends between the distal ends of both the ICWT and the OCWT to cover and / or seal the distal ends and prevent access into the layered region. This ringed tip 1619 may extend over the inner and outer coiled tubes, resulting in a lip or edge 1621 on the inner and / or outer surfaces, depending on the embodiment. In FIG. 16A, the lip 1621 may extend into the inner lumen 1628. Thus, an object, including but not limited to a second (e.g., inner) stiffening device inserted into the lumen 1628 of the exemplary stiffening device shown, could potentially rub against this lip or ridge, potentially damaging the object or preventing the object from moving smoothly and easily in the axial and / or radial directions. Similarly, if the device were inserted into a larger device, a lip or ridge on the outer edge 1622 may also be undesirable for similar reasons.

[0142]

[0169] Therefore, it may be preferable to have a tip or cap region that smoothly transitions over this distal end region to seal these layers, or to seal between the innermost and outermost layers, such as ICWT and OCWT.

[0143]

[0170] Coiled layers including OCWT and ICWT can include a polymeric material surrounding the coil, as described above. In some embodiments, the polymeric material in which the coil is surrounded or embedded can be reinforced to prevent breakage and / or puncture of the coil. In any of these devices, the polymeric material surrounding the coil can be reflowed distally to form an annular seal or tip of the stiffening device. For example, FIG. 16B shows an embodiment of a distal end portion of a stiffening device similar to that shown in FIG. 16A, but where the polymeric material 1631 forming part of the inner coiled tube 1617' is reflowed distally and thus extends over the outer coiled tube 1615 and is wrapped back on or over the outer coiled tube 1615 to form a distal tip (e.g., reflowed tip) 1619'. In this embodiment, the inner coiled tube has been reflowed distally onto the distal edge, however, alternatively or additionally, in some embodiments, the outer coiled tube 1615 can instead be reflowed distally to form the tip 1619'. The configuration shown in Figure 16B can be particularly useful when another device is moved axially into or out of the lumen 1628' of the stiffening device, for example, when the stiffening device is an outer stiffening member of a nested robotic device as described above, which can provide material continuity and eliminate the need for gluing in a separate distal end.

[0144]

[0171] In the embodiment shown in Figure 16B, the polymeric material of the inner coiled tube can be reflowed distally to form a reflowed tip to form the tip 1619' or a portion of the tip of the stiffening device. Although Figure 16B shows one embodiment of a device in which the reflowed tip is folded back and wrapped back over the distal end to contact the outer coiled tube (which can be sealed, glued, or otherwise attached), in some embodiments the reflowed tip is not folded back or wrapped back and can extend distally forward, and in some embodiments the reflowed tip has a funnel shape.

[0145]

[0172] Thus, in general, the distal tip may be formed by a reflowed polymeric material. The resulting reflowed tip may reduce or eliminate any discontinuities (e.g., edges, lips, etc.) between the inner and / or outer coiled tube and the tip of the device. Any suitable fabrication technique may be used to form the distal tip, including the reflowed distal tip. Reflow of the polymeric material may refer to a thermal reflow that reshapes the polymeric material from its original shape to the tip profile. For example, the tip may be formed by using a mandrel to control the shape of the tip. The mandrel may be controlled in shape, thickness (which may be constant and / or variable along the length of the tip or distal end region). The material may be selected to have an appropriate durometer for biocompatibility as well as to prevent damage or puncture of the tip from the device.

[0146]

[0173] FIG. 16C shows an example of a cross section of a portion of a mandrel 1635 that can be used to reflow the polymer material of the device to form a reflowed distal tip. In FIG. 16C, an inner coiled wound tube (ICWT) 1617″ is shown over the mandrel such that a distal end region of the ICWT spreads over the mandrel to form a polymer tip region 1639. This polymer tip region can be a pre-inverted polymer tip (or a funnel-shaped polymer tip). For example, FIG. 16D shows an example of a stiffening device that includes a distally extending funnel-shaped reflowed polymer tip 1619″. The device includes an outer coiled tube 1615 and an inner coiled tube (not shown). FIG. 16E shows another example of a stiffening device that includes a rewound and reflowed polymer tip 1619′ that extends as an annular ring over the distal end and is also sealed to the outer catheter winding tube 1615.

[0147] Shielded Wires

[0174] Any of the stiffening devices described herein can be configured to reduce or prevent the risk of wires (e.g., of a coil in a coiled tube) breaking and / or protruding from the device, which could pose a risk of injury to the patient. For example, any of these devices can include reinforcement in the distal end region where the coil terminates.

[0148]

[0175] For example, Figure 17 illustrates generally one embodiment of a distal end of a stiffening device 1700 including an outer tube stiffening layer 1741. In Figure 17, the device includes a wall volume including an outer stiffening tube 1715 (e.g., an outer coil stiffening tube), an inner stiffening tube 1717 (e.g., an inner coil stiffening tube), a bladder layer 1747, and a variable stiffness layer 1745 (e.g., a braid layer). The distal end of the device is shown including a distal tip region 1752. Shown is a coil 1716 (e.g., one or more helical wires) of the outer stiffening tube, and a coil end 1716' proximal to the distal tip of the device. This distal end region of the coil is covered by a stiffening layer 1741. Any suitable stiffening layer may be used, including polymeric materials, metals, and the like. The reinforcing layer can be puncture resistant and relatively thin (e.g., about 0.0002 inches to 0.002 inches). Examples of materials that can be used for the reinforcing layer can include PET, polyimide, PEEK, aluminum, stainless steel, platinum, and gold. In some embodiments, the reinforcing material is a polyimide film. The reinforcing material can be flush with the exterior surface of the device. In some embodiments, the reinforcing material can be secured by an adhesive. Alternatively, in some embodiments, the reinforcing material can be a heat shrink material or a metal strip (e.g., stainless steel, platinum, gold, etc.) that can be attached over the area including the ends of the coil. The reinforcing layer can be any suitable size (e.g., diameter).

[0149]

[0176] The distal end of any of these devices can be tapered. For example, in FIG. 17, the distal end region can be tapered at 1743, which can allow for easier insertion and / or removal from the body. The distal end region can be tapered to make room for the addition of an outer tube reinforcement layer, so that the overall outer diameter does not increase in this region, or the wall thickness is substantially increased, thus increasing the outer diameter. The outer diameter can remain substantially the same, or can be gradually changed (e.g., tapered) to prevent the formation of a lip or protrusion that could cause injury to the patient or prevent mating through a counter device. The stiffening region can include a radial gap (e.g., between the bladder layer and the outer tube in FIG. 17) to allow the variable stiffness layer to move freely when not stiffened, which can allow for a thinner wall thickness, e.g., waisted, in this distal end region. In some embodiments, as shown in FIG. 17, the distal end region can be located distal to the end of the bladder and variable stiffness region and thus is not a stiffening section.

[0150]

[0177] In any of these devices, the distal end region, including the distal tip, can be configured to be non-stiffened, as described above. In addition, any of these devices can be configured to have a substantially soft distal end. In any of these embodiments, the device can include a longitudinal gap region 1751 between the distal end of the stiffening region and the distal end region of the device. In some embodiments, the device does not include a longitudinal gap. The longitudinal gap 1751 can increase the softness of the distal end region, which can enhance compliance.

[0151]

[0178] As discussed above, these devices can be configured to prevent breakage of the reinforcing coil by adding a reinforcing layer. However, in some cases, it may not be desirable to add additional material, and possibly additional thickness, in this region. For example, in some variations, it may be desirable to re-center or adjust the radial position of the coils in the coiled layer to increase the thickness of the surrounding material, e.g., polymeric material, without increasing the overall radial thickness. In any of these examples, this may mean that the radial position of the coils in the coiled layer (e.g., inner coiled layer and / or outer coiled layer) may be changed (increased or decreased) relative to a more proximal position, such that the end regions are centered relative to the surrounding polymeric material (e.g., matrix material). This may be particularly useful when the coiled layer includes both an inner reinforcing member (e.g., inner coil) and an outer reinforcing member (e.g., outer coil), as discussed above. In some embodiments, one of the inner or outer reinforcing members (e.g., a coil) can terminate proximally relative to the other outer or inner reinforcing member (e.g., a coil), and the other reinforcing member can be radially centrally aligned within the polymer matrix. This is shown in FIG.

[0152]

[0179] FIG. 19 shows an example of a distal end of a portion of a stiffening device including an outer coiled tube 1915 and an inner coiled tube 1917, a variable stiffness layer (e.g., braided layer, woven layer, etc.) 1945, and a bladder layer 1947. In this example, the variable stiffness layer extends all the way to the distal end (distal to the bladder layer) and can be attached to the inner coiled layer. The bladder layer can be sealed to the inner coiled layer proximal to the distal end. The outer coiled layer includes a single coil 1916 helically wound around the outer coiled layer, with the coil 1916 surrounded by a polymer matrix material. In this example, the inner coiled layer includes an upper (e.g., outer) wire 1936 or coil and a lower (e.g., inner) wire 1937 or coil that are counter-wound along the length of the outer coiled tube. In this embodiment, the upper wire end proximal to the distal end region 1953 and the lower wire continue to spiral distally to the distal end region. In the proximal region with inner and outer coils, the pair of coils can be collectively centered within the polymer matrix material as shown in FIG. 19. After the inner coiled tube transitions to a single spiral coil near the distal end region 1927, the radial path of the coiled tube can be adjusted to center the lower wire within the polymer matrix material by redirecting the wire 1929 at the distal end as shown. In some embodiments, the pitch of the redirected wire can be the same. In some embodiments, the pitch can vary, as shown in FIGS. 15A-15D above.

[0153]

[0180] In Figure 19, the overall thickness of the inner coiled tube remains constant at the distal end. Optionally, this thickness can be increased or decreased, and optionally polymeric material can be added in this region to keep the thickness of the inner coiled tube relatively constant (e.g., ±5% or less, ±7% or less, ±10% or less, etc.). This transition from a pair of wound coils in the inner coiled layer can also enhance the softness of the distal end region of the stiffening device, which can be desirable because it helps normalize the transition between rigid and non-rigid devices that move relative to one another, as discussed above (e.g., nested devices).

[0154]

[0181] In any of the stiffening devices described herein, the wall thickness of the device can include gaps or regions through which the variable stiffness layer can move when not compressed by the bladder layer. For example, in FIG. 19, the gap region 1975 is shown between the outer coiled tube 1915 and the variable stiffness layer 1945, but by pressurizing the bladder layer to stiffen the device, the bladder layer presses the variable stiffness layer against the outer coiled tube 1915, reducing the volume of the gap region 1975. Alternatively, in some embodiments, the device is configured such that by pressurizing the bladder layer 1947 (which can be attached to the outer coiled tube or another radially outer layer), the bladder layer presses the variable stiffness layer against the inner coiled tube over the gap layer. This gap layer can be an air gap or filled with any other fluid (e.g., water, etc.). The gap layer can be coupled to one or more vents, e.g., proximal vents, to allow release of fluid (e.g., air) when the bladder layer is pressurized.

[0155]

[0182] In some embodiments, one or more other layers may be augmented or enlarged to prevent breakage and / or failure of components of the stiffening device. In some embodiments, the bladder layer may be reinforced or thickened, for example, by folding it one or more times, adding an additional material, etc. In some embodiments, additional reinforcing material may be added, such as a different material having a higher durometer. For example, FIG. 20 shows a portion of a distal end section of a stiffening device including an inner coiled wound tube (ICWT) 2017, an outer coiled wound tube (OCWT) 2015, a variable stiffness layer 2045, and a bladder layer 2030. In this embodiment, the bladder layer is shown enlarged over the distal end region. In FIG. 20, the variable stiffness layer extends distal to the end of the bladder layer and is attached to the ICWT. The reinforced distal end of the bladder layer may be secured (sealed, glued, bonded, etc.) to the ICWT proximal to the distal end 2053 of the device. Such reinforcements can be made at either end, and since the bladder resides in the midsection region, these additional elements are made separately from the bladder.

[0156]

[0183] In stiffening devices such as that shown in FIG. 20, a thicker bladder in the distal / proximal region can enhance the strength of the distal end region and can be formed by folding back the bladder layer. For example, the bladder can be extruded in a single length and bonded to the ICWT. Since the transition section between the bond and the bladder may not be as robust as it would be otherwise, when the bladder is under the highest amount of stress when pressurized, reinforcing the bladder layer can prevent the seal and / or bladder from breaking under pressure in the distal end region. Optionally, the distal end region of the bladder layer can be reinforced by inverting the bladder layer at the distal end and remelting the material that forms the bladder layer. Alternatively, additional material (including the same material that forms the bladder layer or a different material) can be added.

[0157]

[0184] In the embodiment shown in FIG. 20, the bladder can be bonded (e.g., thermally and / or adhesively) to the ICWT at 2077. This bond can result in high strain areas that can be improved by reinforcement as described above. The reinforcement areas can be any suitable length. For example, the reinforcement areas can be about 0.25, 0.5, and 5 times the diameter of the ICWT. In some embodiments, the reinforcement areas are about 0.4 inches (0.5 inches, 0.6 inches, 0.7 inches, etc.).

[0158]

[0185] Any of the apparatus described herein (including, for example, any of the stiffening devices) can include a proximal end configured to allow for the application of pressure (positive and / or negative) to stiffen the devices described herein while preventing damage or failure of the device. For example, FIG. 18 shows an example of a proximal end region of a device showing the boundaries for an inner tube 1817, an outer tube 1815, and a bladder region 1847. A variable stiffness layer (not shown in FIG. 18) can be attached from the proximal end region or a more distal location.

[0159]

[0186] In FIG. 18, outer tube 1815 is coupled to outer tube adapter 1861, which fits over bladder 1847, which is coupled at a proximal end to bladder adapter 1857. The bladder adapter can be configured to provide a passageway on one side for application of pressure (e.g., positive pressure) while preventing breakage or collapse of the bladder. In some cases, the proximal end region of the bladder may be a relatively weak area that may break when pressure is applied. In some embodiments, the attachment of the bladder to the proximal end of the device may be reinforced by a bladder reinforcement film 1853. This bladder reinforcement film may be adhered at 1864 to the proximal end of the bladder material and over the bladder adapter, as shown in FIG. 18. In particular, the bladder reinforcement film may prevent breakage over gap areas 1852 that may occur where the bladder, bladder adapter, and / or outer tube adapter meet. The bladder reinforcement film can be any suitable material, including additional (or thicker) bladder material (eg, a polymeric material), a material having a higher durometer than the bladder material, or a material having a lower durometer than the bladder material.

[0160] Parallelogram tip shape

[0187] The stiffening devices described herein can be configured to bend at the distal end region in the non-rigid configuration without being compressed, significantly compressed, or reducing the length of the distal end. As a result, this can allow the distal end region to bend by laterally displacing the distal opening ("parallelogramming"), as shown in FIG. 21. Parallelogramming refers to bending that can keep both radial sides of the stiffening device ("tube") substantially parallel. In FIG. 21, the stiffening apparatus includes an inner stiffening member 2105, which is shown telescopically extending from an outer stiffening member 2103. The outer stiffening member can be configured to bend at the distal end region by parallelogramming, such that the length of both radial sides of the outer stiffening member remains substantially the same length as when the outer stiffening member is bent. As a result, bending can occur by a sliding motion, and when the inner stiffening member exits the lumen of the outer member, the plane of the distal opening does not remain parallel to the long axis of the inner stiffening member. As shown in FIG. 21A, a line 2156 perpendicular to the long axis 2155 of the inner stiffening member as it exits the outer stiffening member forms an angle (θ) with respect to the plane of the distal opening 2157 of the outer stiffening member. This angle (θ) increases (up to a limit) with increasing bending in the parallelogramming configuration, compressing both sides within the device. This is shown diagrammatically in FIG. 21B and FIG. 21C. FIG. 21B diagrammatically illustrates an embodiment of a parallelogramming device in which the radial lengths l1, l2 of the distal end region of the outer stiffening device remain approximately equal (e.g., within ±5% or less, 7% or less, etc.) as the distal end region is bent. In this embodiment, the plane of the distal opening 2113 of the schematic device is not perpendicular to the long axis of the inner member as it extends distally from the outer stiffening device. Line 2115 indicates the long axis of the inner member (eg, inner catheter device) as it exits the outer device 2113.In contrast, FIG. 21C shows an embodiment of a device that bends by compressing a first side radially opposite a second side (and / or by expanding both radial sides) such that the lengths (l1, l2) of the two sides become increasingly different as bending of the device occurs.

[0161]

[0188] 21D1 and 21D2 show the action of parallelogramming, showing the resulting radial sliding motion rather than compression of the sides of the example shown. FIG. 21D1 shows one example of a distal end region configured to bend by parallelogramming, and FIG. 21D2 shows a distal end region configured to bend as expected by bending without substantially changing the length 2162 of the sides. In FIG. 21D1, the length 2162 of the path between the proximal and distal ends is approximately the same as the length 2162' in the bent configuration.

[0162]

[0189] 21E shows an embodiment of the stiffening device 2103 being bent in a non-rigid configuration onto the distal end of the tool 2115. In this embodiment, a portion 2142 of the outer coiled tube is bent by parallelogramming.

[0163]

[0190] Parallelogramming can be beneficial to the operation of the stiffening member. Thus, any of these stiffening devices and methods of use thereof can be configured to bend by parallelogramming. In some cases, the additional bending stiffness results in parallelogramming. For example, any of the devices described herein can be configured to provide parallelogramming when bending the distal end region. For example, the device can be configured such that a variable stiffness layer (e.g., braid, fabric, etc.) can extend distal to the bladder layer, and in some embodiments, the variable stiffness layer can extend to the distal end of the device. The variable stiffness layer can limit the ability of the distal end of the device to be compressed or extended in this localized region, thereby providing parallelogramming. In any of these embodiments, the distal end region of the device can also or alternatively be configured such that, if there are dual coils (e.g., upper and lower coils) in the outer and / or inner coil reinforcement members, the upper or lower coil can terminate before the distal end region, as described above and shown in FIG. 21F. In this example, the inner coiled tube 2117 includes a pair of counter-wound coils, with the inner coil 2118 terminating before the distal end (midline 2123 is shown for reference). Figure 21G also shows an example in which the distal end region is further softened by increasing the pitch of the coils extending distally within the distal end region after the second counter-wound coil terminates at 2118, and in this example, a variable stiffness layer 2127 (e.g., a woven, knitted, braided, etc. layer) extends to the distal end of the device.

[0164] Axial Adjustment

[0191] Any of the devices described herein may include an axial adjuster to counteract and relieve strain caused by stiffening the device. In general, application of pressure (positive or, in some embodiments, negative) may result in axial expansion of the length of the device. This may be related to the change in length of the pressurized bladder as it acts on the blade. This axial expansion may be small (e.g., 3 mm or less, 2 mm or less, 1 mm or less), but the resulting strain may pose a risk of damage to the device, especially at the distal or proximal ends of the device. This problem may be particularly acute when the device includes a torsionally stiff member that extends over the length of the device to provide torsional (e.g., rotational) stiffness.

[0165]

[0192] Thus, any of these devices can include an axial adjuster to accommodate axial expansion and contraction of the stiffening device (e.g., when stiffening / de-rigidifying). In any of these examples, the axial adjuster can be configured to couple to a proximal end of the stiffening device and can be coupled to one or more layers forming the stiffening device. In particular, the device can be differentially coupled to some of the one or more layers to allow relative axial movement between some of these layers. The axial adjuster can include a housing and / or one or more internal couplers for coupling to an inner layer (e.g., an outer coiled tube and an inner coiled tube) and a biased expansion element that can be coupled to an inner layer, such as a torsionally stiff layer, and can be configured to flex axially to prevent or relieve strain. The axial adjuster can include a housing, which can also receive and couple to a pressure source (delivering positive and / or negative pressure to the bladder layer to stiffen the device). The axial adjuster can include a thread or shuttle (e.g., a torsional adjuster shuttle) that can move within the stiffening device relative to the housing when the inner and / or outer regions of the device are coupled to the housing and / or connector, and can be coupled (e.g., rigidly coupled) to an inner layer, such as a torsionally stiff layer. The device can include a bias (e.g., a spring) to restore the position of the shuttle or thread, and thus the position of the inner layer, after the stiffening layer is transitioned to a soft state.

[0166]

[0193] Thus, the axial adjuster can be configured to allow for natural variation in the length of the stiffening device.

[0167]

[0194] 22A-22C show one embodiment of an axial adjuster. In this embodiment, the axial adjuster 2200 includes a housing 2270 (e.g., an axial adjuster housing) that includes a distal opening 2282 through which the proximal end of the device can be inserted. Within the housing, a connector 2285 is configured to couple to an outer layer and / or an inner layer of a stiffening device. In this embodiment, the axial adjuster also includes a shuttle 2273 (e.g., an axial expansion / adjuster shuttle) that can be rigidly coupled to an inner layer of a stiffening device, such as a torsionally stiff layer 2271 (e.g., a torsionally stiff inner structure, a portion of which is shown in FIGS. 22A-22B for reference). The shuttle 2273 can be movably held within a collet 2281 such that the shuttle can move axially (in and out) in the long axis of the device 2280. The axial adjuster also includes an expansion chamber 2279 into which the shuttle can slide. The expansion chamber (which may be formed by the housing) may also include rails or tracks that allow axial movement but prevent rotation or other degrees of freedom. The axial adjuster also includes a return bias 2278 (e.g., a coil spring in this example, although other return biases may be used).

[0168]

[0195] In any of these arrangements, the axial adjuster can apply positive or negative pressure to stiffen the device. For example, the axial adjuster can include a pressure inlet 2272 that can apply and direct pressure through one or more channels in the axial adjuster housing body to a region of the stiffening device that includes a bladder, thus forcing the bladder against the variable stiffness layer to stiffen the device. The axial adjuster can also include one or more seals (e.g., o-rings) between the shuttle 2273 and the collet 2281 to prevent loss of pressure.

[0169]

[0196] Generally, these axial adjusters can also be configured as annular devices that can provide an opening through the device to allow passage of the stiffening device in and out of the lumen.

[0170]

[0197] Figure 22C shows an exterior view of the axial adjuster of Figures 22A-B, showing the central lumen 2297 and pressure port 2272 formed on / in the housing, as well as a pair of flanges 2286, 2286'. The flanges can allow for gripping or mounting of the axial adjuster for manual or automated movement of the device (e.g., rotational movement, axial movement, etc.).

[0171]

[0198] As described above, the axial adjuster can be coupled to the proximal end of the device and can allow for the change in length of one or more layers (e.g., length of the torsionally stiff member) during operation of the device, e.g., stiffening / de-rigidifying the stiffening device. In some embodiments, the axial adjuster can be permanently coupled to the proximal end of the device, while in other embodiments, the axial adjuster can be releasably or removably attached. In use, pressure (e.g., positive and / or negative pressure) can be applied to the stiffening device, e.g., through a pressure inlet, to deflect the bladder layer, and a force can be applied against the variable stiffness layer, which can cause the torsionally stiff layer to expand axially (e.g., proximally) by sliding into the expansion chamber (restrained from axial movement without rotation), thereby pushing against the return bias. After the stiffening device is de-rigidified, e.g., by reducing or removing the pressure in the inlet, the return bias can move the shuttle coupled to the torsionally stiff layer distally again. In this manner, the axial adjuster allows for lateral (axial) adjustment of the movement of the torsionally stiff layer, thereby reducing strain on the device.

[0172]

[0199] It should be understood that features described herein with respect to one embodiment may be combined with or substituted for features described herein with respect to another embodiment, for example, various layers and / or features of the stiffening devices described herein may be combined, substituted, and / or rearranged relative to other layers.

[0173]

[0200] It is to be understood that all combinations of the above concepts, and additional concepts discussed in more detail below (provided such concepts are not mutually inconsistent), are contemplated as being part of the inventive subject matter disclosed herein, and can be used to achieve the advantages described herein.

[0174]

[0201] The process parameters and sequences of steps described and / or illustrated herein are given by way of example only and can be modified if desired. For example, the steps illustrated and / or described herein may be illustrated or discussed in a particular order, but the steps do not necessarily have to be performed in the order illustrated or discussed. The various exemplary methods described and / or illustrated herein can also omit one or more of the steps described or illustrated herein or can include additional steps in addition to those disclosed.

[0175]

[0202] When a feature or element is referred to herein as being "on" another feature or element, it can be directly on the other feature or element, or there may be intervening features and / or elements. In contrast, when a feature or element is referred to as being "directly on" another feature or element, there are no intervening features or elements. Also, when a feature or element is referred to as being "connected," "attached," or "coupled" to another feature or element, it should be understood that it can be directly connected, attached, or coupled to the other feature or element, or there may be intervening features or elements. In contrast, when a feature or element is referred to as being "directly connected," "directly attached," or "directly coupled" to another feature or element, there are no intervening features or elements. Although described or illustrated with respect to one embodiment, the features and elements so described or illustrated are applicable to other embodiments. Those skilled in the art will also recognize that when a structure or feature is referred to as being "adjacent" to another feature, it may have portions that overlap or underlie the adjacent feature.

[0176]

[0203] The terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting of the invention. For example, as used herein, the singular forms "a," "an," and "the" are intended to include the plural unless the context clearly indicates otherwise. It is further to be understood that the terms "comprising" and / or "including," as used herein, specify the presence of the described features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any or all combinations of one or more of the associated enumerations and may be abbreviated as " / ."

[0177]

[0204] Spatially relative terms such as "below," "lower," "bottom," "upper," and the like may be used herein to facilitate describing the relationship of one element or feature to another element or feature as depicted in the drawings. It should be understood that these spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the drawings. For example, if the device in the figures were inverted, an element described as being "below" or "below" another element or feature would be oriented "above" that other element or feature. Thus, the illustrative term "below" may encompass both an orientation above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Similarly, terms such as "upward," "downward," "vertical," "horizontal," and the like are used herein for descriptive purposes only, unless specifically indicated otherwise.

[0178]

[0205] In this specification, the terms "first" and "second" may be used to describe various features / elements (including steps), but these features / elements should not be limited by these terms unless the context indicates otherwise. These terms may be used to distinguish one feature / element from another. Thus, a first feature / element described below may also be referred to as a second feature / element, and similarly, a second feature / element described below may also be referred to as a first feature / element without departing from the teachings of the present invention.

[0179]

[0206] Throughout this specification and the claims that follow, unless the context requires otherwise, the word "comprise" and variations such as "comprises" and "comprising" mean that various components may be employed together in methods and articles (e.g., devices and compositions and apparatuses that include methods). For example, the term "comprising" should be understood to imply the inclusion of any described elements or steps, but not the exclusion of any other elements or steps.

[0180]

[0207] In general, it should be understood that any of the apparatus and methods described herein are inclusive, or all or a subset of the components and / or steps may be exclusive, and may be expressed as "consisting of" or "consisting essentially of" various components, steps, subcomponents, or substeps.

[0181]

[0208] Unless expressly specified otherwise, including those used in the examples, all numerical values ​​used in the specification and claims may be interpreted as if they were preceded by the term "about" or "approximately" even if the term is not explicitly stated. The phrase "about" or "approximately" may be used when describing a size and / or location to indicate that the stated value and / or location is within a reasonable expected range of values ​​and / or locations. For example, a numerical value may have a value of + / -0.1% of the stated value (or range of values), + / -1% of the stated value (or range of values), + / -2% of the stated value (or range of values), + / -5% of the stated value (or range of values), + / -10% of the stated value (or range of values), etc. Any numerical value provided herein should also be understood to include "about" or "approximately" that value, unless the context indicates otherwise. For example, if the value "10" is disclosed, then "about 10" is also disclosed. Any numerical range provided herein is intended to include all subranges contained within that range. Also, when a value is disclosed, it is to be understood that "less than or equal to" that value, "more than or equal to" that value, and possible ranges between the values ​​are also disclosed, as would be understood by one of ordinary skill in the art. For example, if a value "X" is disclosed, "less than or equal to X" and "more than or equal to X" (e.g., where X is a number) are also disclosed. It is also to be understood that data are presented in several different forms throughout this application, and that this data represents endpoints and starting points, and ranges for any combination of the data points. For example, if a specific data point "10" and a specific data point "15" are disclosed, it is to be understood that greater than, greater than, less than, less than, and equal to 10 and 15 are also considered to be disclosed, as well as between 10 and 15. It is also to be understood that each unit between two particular units is also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0182]

[0209] Although various exemplary embodiments have been disclosed above, any of a number of modifications may be made to the various embodiments without departing from the scope of the invention as described by the claims. For example, the order in which the various method steps described are performed may often be changed in alternative embodiments, and in other alternative embodiments, one or more method steps may be omitted entirely. Optional features of the various device and system embodiments may be included in some embodiments and not included in other embodiments. Thus, the foregoing description has been presented primarily for illustrative purposes and should not be construed as limiting the scope of the invention as described in the claims.

[0183]

[0210] The examples and illustrations contained herein are illustrative and not limiting of specific embodiments in which the subject matter may be practiced. As previously mentioned, other embodiments are available and may be derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of the present disclosure. Such embodiments of the subject matter of the present invention may be referred to herein, individually or collectively, under the term "invention" for the sole convenience and without any intention of spontaneously limiting the scope of the present application to any single invention or inventive concept when in fact multiple inventions or inventive concepts are disclosed. Thus, although specific embodiments have been shown and described herein, any configuration intended to achieve the same purpose may be substituted for the specific embodiment shown. The present disclosure is intended to cover any modifications or variations of the various embodiments. Combinations of the above embodiments and other embodiments not specifically described herein will be apparent to one of ordinary skill in the art upon reviewing the above description.

Claims

1. A stiffening device comprising: an elongate member including a plurality of layers; a bladder layer between the plurality of layers, wherein end regions of the bladder layer are thicker than a middle region of the bladder; A stiffening device, wherein the stiffening device is configured to stiffen when pressure is applied.

2. 10. The device of claim 1, further comprising a variable stiffness layer, the bladder layer configured to be pressed against the variable stiffness layer by applying positive or negative pressure to pressurize and stiffen the device.

3. The device of claim 1 , wherein the thicker end regions of the bladder layer are augmented with the same material as the bladder.

4. The device of claim 1 , wherein the thicker end regions of the bladder layer are increased by inverting the bladder material.

5. The device of claim 1 , wherein the thicker end regions of the bladder layer are augmented with a material different from the bladder.

6. The device of claim 1 , wherein the thicker end regions of the bladder layer are augmented by structural attachments.

7. The device of claim 1 , wherein the thicker end region does not include a structural attachment.

Images