Patent Publication Number: US-2020276417-A1

Title: Split overtube assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This non-provisional utility application is a continuation-in-part of U.S. patent application Ser. No. 16/805,303 filed Feb. 28, 2020, and titled “MEDICAL DEVICES INCLUDING TEXTURED INFLATABLE BALLOONS,” which application is a continuation-in-part of U.S. application Ser. No. 16/249,550, filed Jan. 16, 2019, and titled “MEDICAL DEVICES INCLUDING TEXTURED INFLATABLE BALLOONS,” which claims priority under 35 U.S.C. § 119(e) from U.S. Patent Application No. 62/617,868, filed Jan. 16, 2018. This application is also related to and claims priority under 35 U.S.C. § 119(e) from U.S. Provisional Application No. 62/849,592, filed May 17, 2019, entitled “MEDICAL DEVICES INCLUDING TEXTURED SURFACES.” The entire contents of each of the foregoing applications are incorporated herein by reference for all purposes. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     This invention was made with government support under grant number 1636203 and 1827787 awarded by the National Science Foundation. The government has certain rights in the invention. 
    
    
     TECHNICAL FIELD 
     Aspects of the present disclosure are directed to overtube assemblies for use in medical procedures and, in particular, to overtube assemblies including textured balloons configured to selectively engage with a physiological lumen to facilitate transport of medical devices within the physiological lumen. 
     BACKGROUND 
     Endoscopy is a procedure wherein a highly trained physician pushes a long flexible endoscope through a physiological lumen of a patient, such as, but not limited to the colon or small bowel. Conventional endoscopes often struggle to complete procedures that involve irregular anatomy or small bowel examination. These factors can lead to missed diagnoses of early state conditions, such as colorectal cancer, which is the third most deadly cancer in America, but which has a 93% survival rate when detected in its initial stages. 
     To complete many of these examinations, double balloon enteroscopy (DBE) is often used. The double balloon system includes two balloons, one attached the front of the scope and one attached to a scope overtube. These balloons serve as anchoring points for the endoscope and provide extra support for the long flexible scope to be directed. When these anchoring balloons are inflated and deflated in succession, they aid in the advancement of the scope. When inflated, the balloons push against the wall of the colon, small bowel, or other physiological lumen, and grip the wall forming an anchor point, reducing movement while the scope pushes against the anchor point. DBE has been shown to be a very successful procedure for irregular anatomy patients and small bowel endoscopy. 
     Balloons commonly used in the art for DBE procedures are conventionally made of smooth latex-like materials. These materials have a low coefficient of friction, especially with the soft, mucous covered wall of the small bowel, colon, and other portions of the gastrointestinal (GI) tract. The low coefficient of friction can cause the balloon to slip prematurely, thus not allowing the scope to properly advance. Over-inflation of the balloons can increase friction with the wall of the small bowel or colon, but at the same time can also cause damage to the patient&#39;s GI tract. 
     Certain enteroscopy devices include the balloons in an overtube that is disposed over the enteroscope. Notably, due to their tubular shape, conventional overtubes require the enteroscope to be inserted through the overtube before insertion of the enteroscope into the patient. As a result, if a physician begins an enteroscopy procedure without an overtube and subsequently determines that an overtube is required, the enteroscope must be fully removed from the patient before attaching the overtube, effectively restarting the enteroscopy procedure. 
     There is thus a need in the art for novel devices that can be used to perform gastroenterology and other medical procedures. Such devices should increase the amount of successful completions of such procedures, and provide a more comfortable experience for the patient. By allowing for more colonoscopies to be completed fully, more cases of colorectal cancer would be found in early enough stages for successful treatment. 
     With these thoughts in mind among others, aspects of the devices and methods disclosed herein were conceived. 
     SUMMARY 
     In one aspect of the present disclosure, an overtube assembly for use with an elongate medical tool is provided. The overtube assembly includes an overtube including a flexible tubular body having a proximal end and distal end and a split extending from the proximal end to the distal end. The overtube assembly further includes an inflatable balloon coupled to a distal portion of the flexible tubular body. The flexible tubular body is disposable over a section of the elongate medical tool by inserting the elongate medical tool through the split. 
     In certain implementations, the flexible tubular body defines an air supply lumen extending from the distal end, the air supply lumen in communication with an internal volume of the inflatable balloon. In such implementations, the flexible tubular body may define an overtube port in communication with the air supply lumen, the inflatable balloon may define a balloon port in communication with the internal volume of the inflatable balloon, and the inflatable balloon may be disposed on the flexible tubular body such that the overtube port is in communication with the balloon port. A conduit may also extend between the overtube port and the balloon port. 
     In other implementations, the inflatable balloon is one of a plurality of inflatable balloons coupled to the distal portion of the flexible tubular body and the flexible tubular body defines a plurality of air supply lumens, each air supply lumen of the plurality of air supply lumens being in communication with an internal volume of a respective inflatable balloon of the plurality of inflatable balloons. In such implementations, the plurality of inflatable balloons may consist of two balloons disposed on opposite sides of the flexible tubular body. Also, in such implementations, each of the air supply lumens may have a diameter of about 0.8 mm and a wall thickness of about 0.33 mm. 
     In still other implementations, the inflatable balloon includes a textured exterior surface. In such implementations, the textured exterior surface includes a plurality of outwardly extending protrusions. 
     In other implementations, the split includes a proximal split portion having a first width and a distal split portion having a second width, the second width being greater than the first width. 
     In still other implementations, the flexible tubular body is formed from at least one of Nylon, PFA, PET, PTFE, FEP, HDPE, TPPE, and Hytrel Thermoplastic Polyester Elastomer with Everglide. 
     In other implementations, the flexible tubular body has a thickness from and including about 0.25 mm to and including about 1.0 mm. 
     In still other implementations, the flexible tubular body includes a first exterior surface portion adapted to provide greater friction with a wall of a physiological lumen than a second exterior surface portion of the flexible tubular body. In such implementations, the first exterior surface portion may include at least one of texturing or a coating. 
     In other implementations, the flexible tubular body includes a first interior surface portion adapted to provide greater friction with an exterior surface of the elongate medical tool than a second interior surface portion of the flexible tubular body. In such implementations, the first exterior surface portion may include at least one of texturing or a coating. 
     In still other implementations, the flexible tubular body includes a first overlapping portion and a second overlapping portion. The first overlapping portion and the second overlapping portion are configured to overlap when the flexible tubular body is disposed over the section of the elongate medical tool and the split is disposed between the first overlapping portion and the second overlapping portion. In such implementations, when overlapping, an interface is formed between an inner surface of the first overlapping portion and an outer surface of the second overlapping portion and at least one of the inner surface of the first overlapping portion and the outer surface of the second overlapping portion includes at least one of texturing or coating. In another of such implementations, when overlapping, an interface is formed between an inner surface of the first overlapping portion and an outer surface of the second overlapping portion. The inner surface of the first overlapping portion includes a first surface structure, the outer surface of the second overlapping portion includes a second surface structure, and the first surface structure is configured to engage the second surface structure when the first overlapping portion overlaps the second overlapping portion. 
     In other implementations, the flexible tubular body includes one or more reinforcement structures extending around the flexible tubular body. 
     In still other implementations the flexible tubular body includes one or more low flexibility regions disposed along the tubular body. In such implementations, the one or more low flexibility regions may include a hole through the tubular body or a local thinning of the tubular body. 
     In other implementations the overtube assembly further includes a zipper closure extending along the split. 
     In still other implementations, the tubular body includes a solid strip extending opposite the split and one or more bands extending circumferentially from the strip toward the split. In such implementations, the tubular body may include a rod adjacent the split and extending along the split and the one or more bands are coupled to the rod. 
     In another aspect of the present disclosure, an overtube for use with an elongate medical tool is provided. The overtube includes a flexible tubular body having a proximal end and distal end, the flexible tubular body including a split extending from the proximal end to the distal end. The flexible tubular body is disposable over a section of the elongate medical tool by inserting the elongate medical tool through the split. 
     In certain implementations, the split includes a proximal split portion having a first width and a distal split portion having a second width, the second width being greater than the first width. 
     In still other implementations, the overtube of claim  24 , wherein the flexible tubular body is formed from at least one of Nylon, PFA, PET, PTFE, FEP, HDPE, TPPE, and Hytrel Thermoplastic Polyester Elastomer with Everglide. 
     In other implementations, the flexible tubular body has a thickness from and including about 0.25 mm to and including about 1.0 mm. 
     In still other implementations, the flexible tubular body includes a first exterior surface portion adapted to provide greater friction with a wall of a physiological lumen than a second exterior surface portion of the flexible tubular body. In such implementations, the first exterior surface portion may include at least one of texturing or a coating. 
     In still other implementations, the flexible tubular body includes a first interior surface portion adapted to provide greater friction with an exterior surface of the elongate medical tool than a second interior surface portion of the flexible tubular body. In such implementations, the first interior surface portion may include at least one of texturing or a coating. 
     In other implementations, the flexible tubular body includes a first overlapping portion and a second overlapping portion. The first overlapping portion and the second overlapping portion are configured to overlap when the flexible tubular body is disposed over the section of the elongate medical tool and the split is disposed between the first overlapping portion and the second overlapping portion. In such implementations, when overlapping, an interface may be formed between an inner surface of the first overlapping portion and an outer surface of the second overlapping portion and at least one of the inner surface of the first overlapping portion and the outer surface of the second overlapping portion includes at least one of texturing or coating. In an alternative implementation, when overlapping, an interface may be formed between an inner surface of the first overlapping portion and an outer surface of the second overlapping portion. The inner surface of the first overlapping portion includes a first surface structure, the outer surface of the second overlapping portion includes a second surface structure, and the first surface structure is configured to engage the second surface structure when the first overlapping portion overlaps the second overlapping portion. 
     In still other implementations, the flexible tubular body includes one or more reinforcement structures extending around the flexible tubular body. 
     In other implementations, the flexible tubular body defines one or more voids disposed along the tubular body. 
     In still other implementations, the flexible tubular body includes one or more low flexibility regions disposed along the tubular body. In such implementations, the low flexibility regions may include a hole through the tubular body or a local thinning of the tubular body. 
     In other implementations, the overtube further includes a zipper closure extending along the split. 
     In still other implementations, the tubular body includes a solid strip extending opposite the split and one or more bands extending circumferentially from the strip toward the split. In such implementations, the tubular body may include a rod adjacent the split and extending along the split, the one or more bands being coupled to the rod. 
     In yet another aspect of the present disclosure, an overtube assembly for use with an elongate medical device is provided. The overtube assembly includes an overtube including a flexible tubular body. The flexible tubular body has a proximal end and distal end and includes a split extending from the proximal end to the distal end. The flexible tubular body further defines a first air supply lumen extending from the proximal end to a first overtube port and a second air supply lumen extending from the proximal end to a second air supply port. The overtube assembly further includes a first inflatable balloon coupled to a distal portion of the flexible tubular body. The first inflatable balloon includes a first internal volume and defines a first balloon port, the first balloon port in communication with the first overtube port. The overtube assembly further includes a second inflatable balloon coupled to the distal portion of the flexible tubular body. The second inflatable balloon has a second internal volume and defines a second balloon port, the second balloon port in communication with the second overtube port. The flexible tubular body is disposable over a section of the elongate medical tool by inserting the elongate medical tool through the split. 
     In certain implementations, the first inflatable balloon includes a first textured exterior surface and the second inflatable balloon includes a second textured exterior surface. Each of the first textured exterior surface and the second textured exterior surface further includes a plurality of outwardly extending protrusions. 
     In other implementations, the split includes a proximal split portion having a first width and a distal split portion having a second width, the second width being greater than the first width. 
     In another aspect of the present disclosure, a method of manufacturing an overtube assembly is provided, the overtube assembly including an overtube. The method includes coupling an inflatable balloon to an elongate tubular body of the overtube. The elongate tubular body includes a split extending from a proximal end of the elongate tubular body to a distal end of the elongate tube body and the elongate tubular body defines an air supply lumen and an overtube port in communication with the air supply lumen. The inflatable balloon has an internal volume and a balloon port in communication with the internal volume and coupling the inflatable balloon to the elongate tubular body includes coupling the elongate tubular body to the inflatable balloon such that the overtube port is in communication with the balloon port. 
     In certain implementations, the method further includes forming the elongate tubular body. In such implementations, the elongate tubular body may be formed without the split and forming the elongate tubular body includes forming the split in the elongate tubular body. Further in such implementations the elongate tubular body is extruded with a seam extending from the proximal end to the distal end and forming the split in the elongate tubular body includes splitting the elongate tubular body along the seam. 
     In other implementations, forming the elongate tubular body includes extruding the elongate tubular body. 
     In still other implementations, the method further includes after forming the split in the elongate tubular body, coupling a zipper closure to each side of the split. 
     In other implementations, the method further includes, after forming the elongate tubular body, modifying the flexibility of the tubular body at a location along the tubular body. In such implementation, modifying the flexibility of the tubular body may include at least one of thinning a portion of the tubular body at the location or forming a hole at the location. 
     In still other implementation, the method further includes forming the air supply port and forming the balloon port. In such implementations, forming the air supply port and the balloon port may include puncturing each of the elongate tubular body and the inflatable balloon with a hollow conduit such that the hollow conduit extends between the internal volume of the balloon and the air supply lumen. 
     In other implementations, when coupled to the elongate tubular body, the balloon has an open proximal end, the method further including sealing the open proximal end. 
     In still other implementations, the split includes a proximal split portion having a first width and a distal split portion having a second width, the second width being greater than the first width, the method further includes forming the distal split portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example implementations of the present disclosure are illustrated in referenced figures of the drawings. It is intended that the implementations and corresponding figures disclosed herein are to be considered illustrative rather than limiting. 
         FIG. 1A  is a side elevation view of a first medical device according to the present disclosure including a balloon in a deflated state. 
         FIG. 1B  is a cross-sectional view of the medical device of  FIG. 1A . 
         FIG. 10  is a side elevation view of the medical device of  FIG. 1A  in which the balloon is in an at least partially inflated state. 
         FIG. 1D  is a cross-sectional view of the medical device of  FIG. 10 . 
         FIG. 1E  is a side elevation view of the medical device of  FIG. 1A  in the at least partially inflated state and further including a detail view illustrating protrusions disposed on the balloon. 
         FIGS. 2A-2AD  are various views of example protrusions according to the present disclosure. 
         FIG. 3  is a side elevation view of an alternative balloon according to the present disclosure. 
         FIG. 4A  is a schematic illustration of a textured portion of a balloon according to the present disclosure in a first state of strain. 
         FIG. 4B  is a cross-sectional view of a protrusion of the balloon of  FIG. 4A . 
         FIG. 5A  is a schematic illustration of the textured portion of the balloon of  FIG. 4A  in a second state of strain. 
         FIG. 5B  is a cross-sectional view of the protrusion of  FIG. 4B  when the balloon of  FIG. 4A  is in the second state of strain. 
         FIGS. 6A-6B  are more detailed illustrations of the cross-sectional views of  FIGS. 4B and 5B . 
         FIG. 7  is a graph illustrating an example relationship between separation force and a strain applied to a balloon in accordance with the present disclosure. 
         FIG. 8  is a cross-sectional view of a first mold for manufacturing balloons in accordance with the present disclosure. 
         FIG. 9  is an isometric view of a second mold for manufacturing balloons in accordance with the present disclosure. 
         FIG. 10  is a schematic illustration of a medical device in the form of a catheter delivery tool in accordance with the present disclosure. 
         FIG. 11  is a schematic illustration of an example endoscopic medical device in accordance with the present disclosure and including a catheter-mounted balloon. 
         FIG. 12  is a schematic illustration of a second example endoscopic medical device in accordance with the present disclosure and including an endoscope-mounted balloon. 
         FIG. 13  is a schematic illustration of a third example endoscopic medical device in accordance with the present disclosure and including each of a catheter-mounted balloon and an endoscope-mounted balloon. 
         FIG. 14  is a schematic illustration of a fourth example endoscopic medical device in accordance with the present disclosure and including an overtube-mounted balloon. 
         FIG. 15  is a schematic illustration of a fifth example endoscopic medical device in accordance with the present disclosure and including each of a catheter-mounted balloon and an endoscope-mounted balloon. 
         FIG. 16  is a schematic illustration of a sixth example endoscopic medical device in accordance with the present disclosure and including each of a catheter-mounted balloon, an endoscope-mounted balloon, and an overtube-mounted balloon. 
         FIG. 17  is a graphical illustration of an example medical procedure performed using the medical device of  FIG. 13 . 
         FIG. 18  is a flowchart illustrating an example method of performing a procedure using a medical device according to the present disclosure. 
         FIG. 19  is a flowchart illustrating a method of modifying engagement between a balloon in accordance with the present disclosure and a physiological lumen. 
         FIGS. 20A-20B  are schematic illustrations of another example balloon in accordance with the present disclosure in each of an at least partially inflated state and a collapsed state, respectively. 
         FIGS. 21A-210  are schematic illustrations of yet another example balloon in accordance with the present disclosure in each of a collapsed state, a partially inflated state, and an inflated state, respectively. 
         FIGS. 22A and 22B  are schematic illustrations of another example balloon in accordance with the present disclosure in each of a collapsed state and an at least partially inflated state, respectively, illustrating controlled collapse of the balloon. 
         FIGS. 23A-23C  are schematic illustrations of still another example balloon in accordance with the present disclosure in each of an unstrained state, a collapsed state, and an inflated/strained state, respectively, illustrating an alternative approach to controlled collapse of the balloon. 
         FIG. 24  is a cross-sectional view of an example balloon having varying wall thickness to facilitate controlled collapse of the balloon. 
         FIGS. 25A-25D  are isometric, plan, end, and partial cross-sectional views of an example balloon having textured portions including transverse protrusions. 
         FIGS. 26A-26D  are isometric, plan, end, and partial cross-sectional views of another example balloon having textured portions including transverse protrusions. 
         FIGS. 27A-27D  are isometric, plan, end, and partial cross-sectional views of an example balloon having texturing portions including radial protrusions. 
         FIGS. 28A and 28B  are schematic illustrations of a first directional balloon in a collapsed state and an at least partially inflated state, respectively. 
         FIGS. 29A and 29B  are schematic illustrations of a second directional balloon in a collapsed state and an at least partially inflated state, respectively. 
         FIGS. 30A and 30B  are schematic illustrations of a balloon having non-uniform inflation in a collapsed state and an at least partially inflated state, respectively. 
         FIG. 31  is a cross-sectional view of a balloon including multiple and independently inflatable internal chambers. 
         FIG. 32  is a cross-sectional view of a balloon including an outer sheath/balloon and independently inflatable internal balloons disposed within the outer sheath/balloon. 
         FIGS. 33-35  illustrate various implementations of protrusion reinforcement on internal surfaces of balloons in accordance with the present disclosure. 
         FIGS. 36-38  illustrate various implementations of protrusion reinforcement on external surfaces of balloons in accordance with the present disclosure. 
         FIG. 39  is a schematic illustration of an overtube assembly according to the present disclosure including an integrated inflation/deflation assembly. 
         FIGS. 40A-40B  are schematic illustrations of an endoscope and split overtube according to the present disclosure in each of a decoupled and coupled arrangement, respectively. 
         FIG. 41  is a cross-section view of the split overtube of  FIGS. 23A-23B  including an inner layer/coating. 
         FIG. 42  is a cross-section view of the split overtube of  FIGS. 23A-23B  including inner texturing. 
         FIGS. 43-46  are cross-sectional views of alternative split overtubes. 
         FIG. 47  is an isometric view of a distal portion of a split overtube assembly in accordance with the present disclosure. 
         FIG. 48  is a plan view of the distal portion of the split overtube assembly of  FIG. 47 . 
         FIG. 49  is a side elevation view of the distal portion of the split overtube assembly of  FIG. 47 . 
         FIG. 50  a distal end view of the distal portion of the split overtube assembly of  FIG. 47 . 
         FIG. 51  is a cross-sectional side view of the distal portion of the split overtube assembly of  FIG. 47 . 
         FIG. 52  is a detailed view of a distal end of the split overtube assembly of  FIG. 47 . 
         FIGS. 53 and 54  are an isometric view and an end view of an inflatable balloon of the overtube assembly of  FIG. 47 . 
         FIGS. 55 and 56  are isometric views of the distal portion of the split overtube assembly illustrating the inflatable balloons in an unsealed and sealed state, respectively. 
         FIG. 57  is an isometric view of a distal portion of an overtube assembly according to the present disclosure. 
         FIG. 58  is a distal end view of the overtube assembly of  FIG. 57 . 
         FIG. 59  is an isometric view of another overtube assembly according to the present disclosure. 
         FIG. 60  is a detailed isometric view of a distal portion of the overtube assembly of  FIG. 59 . 
         FIG. 61  is a detailed view of a portion of the overtube assembly of  FIG. 59  illustrating a closure mechanism. 
         FIG. 62  is a cross-sectional view of a split overtube assembly including a closure tool. 
         FIG. 63  is a flow chart describing an example method of manufacturing an overtube assembly, such as the overtube assembly of  FIG. 47 . 
         FIGS. 64A-64C  illustrate insertion of an endoscope into a physiological lumen using an expandable overtube in accordance with the present disclosure. 
         FIG. 65  is a schematic illustration of an endoscope disposed within a physiological lumen, the endoscope including a textured endoscopic tool. 
         FIG. 66  is a schematic illustration of an endoscope disposed within a physiological lumen, the endoscope including a textured catheter. 
         FIG. 67  is a schematic illustration of a textured biliary/pancreatic stent according to the present disclosure. 
         FIGS. 68A-68C  are schematic illustrations of a physiological lumen illustrating deployment of a tubular mesh stent according to the present disclosure. 
         FIG. 69  is a schematic illustration of a tapered stent according to the present disclosure. 
         FIG. 70  is an operational environment and, in particular, a cross-sectional view of a patient abdominal cavity including textured surgical tools in accordance with the present disclosure. 
         FIG. 71  is a side elevation view of a surgical tool of  FIG. 64  in which the texturing is integrated with a shaft of the surgical tool. 
         FIG. 72  is a side elevation view of the surgical tool of  FIG. 64  in which the texturing is provided by a sheath or wrap applied to the shaft of the surgical tool. 
     
    
    
     DETAILED DESCRIPTION 
     The current disclosure relates in part to balloon designs that can be incorporated into medical devices, such as endoscopes. The current disclosure further relates to overtubes incorporating such balloons that may be coupled to medical devices, such as endoscopes. More particularly, the current disclosure relates to balloons having exterior surfaces that are at least partially textured. Texturing of the balloons is achieved by the inclusion of multiple pillar-like protrusions extending from the surface of the balloon. In at least one application of the current disclosure, a medical device including the balloon is disposed within a physiological lumen with the balloon in a substantially deflated state. The physiological lumen may be a portion of a patient&#39;s GI tract, but more generally may be any vessel, airway, duct, tract, stricture, sphincter, biliary stricture, or similar physiological structure. Once positioned within the physiological lumen, the balloon may be inflated such that the protrusions contact the lumen wall, thereby engaging the balloon and medical device with the lumen wall. The balloon may be subsequently deflated to facilitate disengagement of the protrusions from the wall of the lumen, thereby permitting movement of the medical device. Accordingly, the balloons (or similar structures) disclosed herein include textured/patterned surfaces that provide increased friction and adhesion with biological tissue as compared to conventional smooth balloons. As a result of such increased friction and adhesion, balloons in accordance with the present disclosure more reliably engage biological tissue as compared to conventional balloon designs. 
     As described below in further detail, the shape and distribution of the protrusions may vary in applications of the present disclosure to provide varying degrees of traction between the balloon and the biological tissue with which the balloon is in traction. In certain implementations, the protrusions may also be configured to deform in response to a strain applied to the balloon. Such deformation alters the adhesive and frictional properties of the protrusions. As a result, a physician may control the relative traction of the balloon to the biological tissue by selectively inflating or deflating the balloon. For example, a physician may apply a first strain to the balloon (e.g., by inflating the balloon to a first extent) resulting in a first degree of deformation of the protrusions and a corresponding first engagement level of the balloon (e.g., a first level of engagement based on the adhesive and frictional properties of the protrusions when in a first shape). Subsequently, the physician may apply a second strain (e.g., by modifying the degree to which the balloon is inflated) resulting in a second degree of deformation of the protrusions and a corresponding second engagement level of the balloon. 
     In certain implementations of the present disclosure, the foregoing balloons may be incorporated into an overtube assembly that may be coupled to an endoscope (or similar elongate medical device) to facilitate transit of the endoscope within a physiological lumen of a patient. In at least some implementations, the overtube assembly includes a split overtube that facilitates coupling of the overtube assembly without removing the endoscope from a patient. 
     Although discussed herein primarily in the context of endoscopic balloons for use in the GI tract, the present disclosure may be used in a variety of medical and non-medical applications. Accordingly, to the extent that any particular applications of the present disclosure are discussed herein, such applications should not be viewed as limiting the scope of the present disclosure. Nevertheless example implementations of the present disclosure are discussed below to provide additional details regarding aspects of the present disclosure. 
       FIGS. 1A-1E  are various views of an example medical device  100  including an inflatable balloon  102  in accordance with the present disclosure. More specifically,  FIG. 1A  is a side elevation view of the medical device  100  with the balloon  102  in deflated or collapsed state,  FIG. 1B  is a cross-sectional view along cross-section A-A of the balloon  102  of  FIG. 1A ,  FIG. 10  is a side elevation view of the medical device  100  in an at least partially inflated state,  FIG. 1D  is a cross-sectional view along cross-section A′-A′ of the balloon  102  of  FIG. 10 , and  FIG. 1E  is a side elevation view of the medical device  100  including an inlay illustrating a textured portion  104  of the balloon  102 . 
     For purposes of the present disclosure, balloons disclosed herein are described as being in various states corresponding to various stages of inflation and deflation. An “unstrained state”, for example, refers to a state in which in which the corresponding balloon may be partially inflated but not yet subject to strain and, as a result, generally corresponds to the “as-molded” shape of the balloon. A “strained state” generally refers to a state in which a balloon is inflated beyond the extent necessary to achieve the unstrained state. A “collapsed state”, in contrast, generally refers to a state of the balloon in which at least a portion of the balloon constricts or is otherwise reduced as compared to the unstrained state. In certain implementations, balloons in accordance with the present disclosure may be biased into a collapsed state. Alternatively, balloons in accordance with the present disclosure may transition into the collapsed state in response to air (or other gas) being removed from the balloon or in response to the balloon being otherwise deflated from the unstrained state. Balloons herein may also be described as being “at least partially inflated”, which generally refers to a state of the balloon including the unstrained state and any degree of inflation beyond the unstrained state. Similarly, the “collapsed” state may generally refer to balloons that are in any degree of collapse up to but excluding the unstrained state. 
     During use, the medical device  100  may be inserted into and located within a physiological lumen of a patient. Such insertion may generally be performed while the balloon  102  is in the deflated state illustrated in  FIG. 1A . Once properly located, air or a similar fluid medium may be provided to the balloon  102  to inflate the balloon, as shown in  FIG. 1B . When such inflation is performed with the balloon  102  within the physical lumen, at least a part of the textured portion  104  may be made to abut an inner wall of the physiological lumen, thereby causing frictional and adhesive engagement between the textured portion  104  and the physiological lumen and mucosal lining. 
     Various arrangements for the balloon  102  on the medical device  100  are feasible. In the specific example of  FIGS. 1A-1E , the balloon  102  has a cylindrical body capped by hemispherical ends. In another non-limiting example, the balloon  102  is disposed around an endoscope  101  or similar tubular body of the medical device  100  such that the balloon  102  forms a toroidal or spherical shape having a central lumen. In another non-limiting example, the balloon  102  is disposed around the endoscope  101  forming a cylindrical shape having hemispherical rounded ends, wherein the endoscope  101  runs along the major axis of the cylinder. In other implementations, the balloon  102  may be ellipsoid in shape or “pill” shaped. Regardless of the foregoing, balloons in accordance with the present disclosure may be substantially any shape as desired. 
     The balloon  102  may be made of at least one non-rigid material. For example, in one example implementation the balloon material may include one or more of low-density polyethylene (LDPE), latex, polyether block amide (e.g., PEBAX®), silicone, polyethylene terephthalate (PET/PETE), nylon, polyurethane, and any other thermoplastic elastomer, siloxane, or other similar non-rigid materials. In certain implementations, the balloon  102  may be formed from one material; however, in other implementations the balloon  102  may be formed from multiple materials. For example, the balloon  102  may include a body formed from a first material but may also include reinforcing or structural members formed from a second material. 
     Material selection for the balloon  102  may also be based, in part, on material hardness. Although material hardness may vary based on application, in at least one specific implementation, the balloon  102  may be formed from a material having a predetermined hardness of Shore 30A such as, but not limited to, Dow Corning Class VI Elastomer C6-530, which is a liquid silicone rubber elastomer. 
     In general, the balloon  102  has a first diameter or shape when in a collapsed or unstrained state and a second diameter when inflated into an unstrained state, the second diameter being larger than the first diameter. In certain implementations, the balloon  102  may be further inflatable beyond the unstrained state into a strained state. For example, in at least one implementation the balloon  102  can be strained up to about 1,000% relative to its uninflated state, although other maximum strain levels are possible. In other implementations, the balloon  102  does not have a set lower inflation limit. The balloon  102  may also be configured to be inflated to a first turgid state having a defined shape and then be further inflated up to a maximum strain while retaining the defined shape. 
     The balloon  102  may be structured such that, when deflated or due to biasing, the balloon  102  collapses into a particular shape. For example, as illustrated in  FIGS. 1A and 1B , the balloon  102  may be configured to collapse into a star or similar shape. Such controlled collapse of the balloon  102  may achieved in various ways including, without limitation, selectively reinforcing portions of the balloon  102  with additional material and including semi-rigid structural elements coupled to or embedded within the balloon  102 . In other implementations, the balloon  102  may form a pill, ovoid, or similar elongated shape when deflated, including a shape that substantially corresponds to the inflated shape of the balloon  102 . 
     As illustrated  FIG. 10 , the balloon  102  includes at least one textured portion  104 . In general and as illustrated in the inlay of  FIG. 10 , the textured portion  104  includes multiple protrusions, such as protrusion  106 , extending from a surface  103  of the balloon  102 . The protrusions  106  of the textured portion  104  may have any pattern. For example and without limitation, the textured portion  104  may include evenly spaced protrusions arranged in a regular geometric pattern, such as a grid. The balloon  102  illustrated in  FIG. 10 , for example, includes protrusions arranged in a triangular grid pattern. In other implementations, other grid patterns may be used including, without limitation, square, rectangular, hexagonal, and octagonal grid patterns or any other suitable grid pattern based on a tessellation of geometric shapes. In certain implementations, the textured portion  104  may include multiple areas of protrusions, with each area having a different protrusion density or protrusion pattern. In still other implementations, the protrusions may be arranged in a random or semi-random pattern across the textured portion  104 . More generally, textured portions in accordance with implementations of the present disclosure may include any suitable arrangement of protrusions. 
     In certain implementations, the protrusions  106  may be evenly spaced such that the center-to-center dimension between adjacent protrusions is constant in a given state of the balloon  102  (e.g., the unstrained state). For example, in one implementation the center-to-center spacing between protrusions (as indicated in the inlay of  FIG. 1E  by dimension “d”) may be about 20 μm to about 1,000 μm in the unstrained state. In other implementations, the protrusions may be evenly spaced with a center-to-center spacing from and including about 50 μm to and including about 750 μm apart from one another. In yet another implementation, the protrusions may be evenly spaced with a center-to-center spacing from and including about 100 μm to and including about 600 μm apart from one another. In still other implementations, the center-to-center spacing between protrusions may be greater than 1000 μm. 
     The inset of  FIG. 1E  illustrates the protrusions  106  arranged in longitudinally extending rows with adjacent rows being offset but equally spaced. It should be appreciated, however, that in other implementations of the present disclosure, aspects of the arrangement of the protrusions  106  may vary. For example, in certain implementations, protrusions of adjacent longitudinal rows may be aligned with each other. Similarly, all rows may be spaced uniformly (e.g., all rows may be spaced 1000 μm apart). Alternatively, spacing between all rows may vary or may only be uniform for a subset of adjacent rows. As yet another example, rows of the protrusions may extend along varying lengths of the textured portion  104 . Moreover, in at least certain implementations, the protrusions  106  may not be arranged in longitudinal rows. Rather, the protrusions may be arranged in any suitable pattern including, without limitation, circumferential rows, biased rows (e.g., rows extending both longitudinally and circumferentially), or in a random or pseudo-random pattern. 
     The protrusions  106  may be formed in various ways. For example and without limitation, the protrusions may be integrally formed with the balloon  102  (e.g., by simultaneously molding the balloon  102  and the protrusions), may be separately formed from and subsequently attached to the balloon  102  (e.g., by first extruding the balloon and then adhering the protrusions to the balloon  102 ), or may be formed directly onto the balloon  102  (e.g., by a co- or over-molding process in which the balloon  102  is first molded and then the protrusions are molded onto the balloon  102 ). 
     As previously discussed, balloons according to the present disclosure may be configured to inflate or deflate in a particular manner. For example, as illustrated in  FIG. 1A , the balloon  102  is configured to collapse into a star- or clover-shape when deflated. More specifically, the balloon  102  is configured such that certain longitudinal sections of the balloon  102  are collapsed to a greater degree than others when air is removed from the balloon  102 . Such selective collapse may be achieved, for example, by increasing the thickness of the balloon  102  in the longitudinal portions that are to remain protruding when the balloon  102  is deflated. 
     A similar design is illustrated in  FIGS. 20A-20B . More specifically,  FIG. 20A  illustrates a balloon  2002  in an at least partially inflated state while  FIG. 20B  illustrates the balloon  2002  in a collapsed state. Similar to the balloon  102  of  FIGS. 1A-1B , the balloon  2002  is configured to selectively collapse when deflated. More specifically, and as illustrated in  FIG. 20B , the balloon  2002  is generally divided into alternating axial bands configured to have different diameters when collapsed. For example, a first band  2010  is configured to collapse to a lesser degree than a second band  2012 . As previously noted, such selective collapse may be achieved by increasing the thickness of the first band  2010  or by otherwise reinforcing the first band  2010 . In other implementations, the shape of at least some of the bands when in the deflated state may be dictated by a mandrel or similar body disposed within the balloon  2002  and about which the balloon  2002  collapses when deflated. 
     Varying the degree to which the balloon collapses, as illustrated in the examples of  FIGS. 1A-1B and 20A-20B , facilitates insertion and transportation of the balloon when in the deflated state. In particular, by reducing the proportion of protrusions that are outwardly/radially facing or otherwise disposed at a maximum diameter, the overall adhesion and friction provided by the balloon is reduced. As a result, the likelihood and amount of contact between the balloon and a wall of a physiological lumen is significantly reduced. Referring to  FIGS. 20A-20B , for example, the balloon  2002  includes a textured portion  2004  having protrusions according to the present disclosure. When in the at least partially inflated state (as shown in  FIG. 20A ), each of the protrusions is directed substantially outwardly/radially and, as a result, is able to readily contact and engage the wall of the physiological lumen. However, when in the collapsed state (as shown in  FIG. 20B ), sections of the textured portion  2004  of the balloon  2002  (such as faces  2006  and  2008 ) and their respective protrusions are directed at least partially in a longitudinal direction and, as a result, are less likely to directly engage the wall of the physiological lumen. Similarly, sections of the textured portion  2004  (such as the second band  2012 ) may be recessed when the balloon  2002  is in the deflated state relative to other sections of the textured portion  2004  (such as the first band  2010 ). As a result the recessed sections are less likely to contact and engage the wall of the physiological lumen. 
       FIGS. 21A-210  illustrates another example balloon  2102  exhibiting non-uniform inflation/deflation.  FIG. 21A  illustrates the balloon  2102  in a collapsed or unstrained state and in which the balloon  2102  assumes a pill-shaped configuration. As shown in  FIG. 21B , the balloon  2102  may be inflated to a first inflation level in which the balloon  2102  assumes an hourglass (or similar shape) in which at least a portion of the balloon  2102  expands to a diameter (d1) that is less than a diameter (d2) of other portions of the balloon  2102 . At a second inflation level, the balloon  2102  may expand such that the diameter of the balloon is substantially uniform (d3). 
     In certain implementations, the controlled inflation of the balloon  2102  may be used to vary the adhesive and frictional force between the balloon  2102  and a wall of a physiological lumen within which the balloon  2102  is disposed. For example, the balloon  2102  includes a textured portion  2104  having protrusions according to the present disclosure. When in the partially inflated state (as illustrated in  FIG. 21B ), the diameter of the textured portion  2104  varies such that only a limited proportion of the protrusions are each of disposed at the maximum diameter of the balloon  2102  and oriented in an outward/radial direction. As a result, the adhesion and friction between the balloon  2102  and wall of the physiological lumen is reduced as compared to when the balloon  2102  is further inflated (as illustrated in  FIG. 21C ) such that substantially all of the textured portion  2104  is at the same diameter. Accordingly, a user of the balloon  2102  may inflate the balloon  2102  to the first inflation level to achieve a first degree of engagement and to the second inflation level to achieve a second, greater degree of engagement. 
       FIGS. 22A and 22B  illustrate another example balloon  2202 .  FIG. 22A  illustrates the balloon  2202  in a collapsed state while  FIG. 22B  illustrates the balloon  2202  in an at least partially inflated state. As shown, the balloon  2202  generally includes textured portions  2204 A,  2204 B disposed between two untextured ends  2206 A,  2206 B. The balloon  2202  also includes an untextured portion  2208  disposed between the textured portions  2204 A,  2204 B. 
     The textured portions  2204 A,  2204 B and the untextured ends  2206 A,  2206 B are structured such that, when in the collapsed state illustrated in  FIG. 22A , the textured portions  2204 A,  2204 B have a maximum diameter (d4) that is less than a maximum diameter (d5) of the untextured ends  2206 A,  2206 B. In such an arrangement, the outermost surface of the balloon  2202  is provided by the untextured ends  2206 A,  2206 B while the textured portions  2204 A,  2204 B are disposed radially inward of the outermost surface. In other words, when in the collapsed state, the textured portions  2204 A,  2204 B may become concave. As a result, when in the collapsed state illustrated in  FIG. 22A , contact between the balloon  2202  and an inner surface of a physiological lumen within which the balloon  2202  may be disposed is primarily between the inner surface of the physiological lumen and the untextured ends  2206 A,  2206 B. 
     As the balloon  2202  is inflated, the diameter of the textured portions  2204 A,  2204 B may expand to at least equal that of the untextured ends  2206 A,  2206 B, as illustrated in  FIG. 22B . As a result, the textured portions  2204 A,  2204 B may come into contact with the inner surface of the physiological lumen, thereby increasing friction between the balloon  2202  and the inner surface of the physiological lumen. 
     In light of the arrangement illustrated in  FIGS. 22A and 22B , the balloon  2202  may be inserted into and moved along the physiological lumen in the deflated/low-friction state illustrated in  FIG. 22A . When the balloon  2202  is at an intended location, the balloon  2202  may then be inflated to expose the textured portions  2204 A,  2204 B and to cause the textured portions  2204 A,  2204 B to come into contact with the inner surface of the physiological lumen. Doing so increases friction between the balloon  2202  and the inner surface of the physiological lumen and may be used to anchor or otherwise reduce movement of the balloon  2202  within the physiological lumen. 
     As illustrated in  FIGS. 22A and 22B , in at least some implementations of the present disclosure, an untextured portion  2208  may be disposed between textured portions of the balloon  2202 . For example, one or more untextured portions  2208  may extend longitudinally between textured portions of the balloon  2202 , such as the textured portions  2204 A,  2204 B. When in the collapsed state illustrated in  FIG. 22A , the untextured portion  2208  may have a diameter similar to that of the untextured ends  2206 A,  2206 B, thereby providing another low-friction surface that contacts the inner surface of the physiological lumen during insertion and transportation. In such cases, when in the deflated configuration, the textured portions  2204 A,  2204 B may generally be concave about an axis extending perpendicular to a longitudinal axis of the balloon  2202 . Alternatively, the untextured portion  2208  may deflate similar to the textured portions  2204 A,  2204 B. In such implementations, the untextured portion  2208  may similarly become concave when deflated, giving the balloon  2202  an “hourglass” or similar shape that tapers radially inward from the untextured ends  2206 A,  2206 B when in the deflated state. 
       FIGS. 23A-23C  are cross-sectional views of a third balloon  2302  including features to selectively collapse portions of the balloon  2302  when in the deflated state. More specifically,  FIG. 23A  illustrates the balloon  2302  in an unstrained state,  FIG. 23B  illustrates the balloon  2302  in a collapsed state, and  FIG. 23C  illustrates the balloon  2302  in a strained inflated state in which the balloon is inflated to a greater extent than as illustrated in  FIG. 23A . As shown, the balloon  2302  generally includes textured portions  2304 A,  2304 B and untextured portions  2306 A,  2306 B extending circumferentially between the textured portions  2304 A,  2304 B. In at least certain implementations, the balloon  2302  may also include untextured proximal and distal ends, as included in other implementations of the present disclosure. As illustrated in each of  FIGS. 23A-23C , each of the textured portions  2304 A,  2304 B generally includes a plurality of protrusions, such as protrusions  2320 . 
     In contrast to textured portions  2204 A,  2204 B of the balloon  2202  of  FIGS. 22A and 22B , in which the textured portions  2204 A,  2204 B becomes concave about an axis perpendicular to a longitudinal axis of the balloon  2202 , the balloon  2302  is configured such that the textured portions  2304 A,  2304 B become concave about an axis parallel to the longitudinal axis of the balloon  2302 . As illustrated in  FIG. 23B , when in the collapsed state, the concavity of the textured portions is such that the protrusions  2320  are disposed within a maximum radius defined by the untextured portions  2306 A,  2306 B. As a result, when in the deflated state, the balloon  2302  may be inserted into and/or transported through a physiological lumen with reduced interaction between the textured portions  2304 A,  2304 B and an inner surface of the physiological lumen. When in an intended position, the balloon  2302  may then be inflated such that the textured portions  2304 A,  2304 B expand from the concave configuration, thereby causing contact between the protrusions  2320  the inner surface of the physiological lumen. Doing so increases frictional engagement between the balloon  2302  and the inner surface, up to and including frictional engagement sufficient to anchor the balloon  2302  in place within the physiological lumen. 
     Controlled collapsing/concavity of balloons in accordance with the present disclosure may be achieved in various ways. For example and without limitation, portions of the balloon intended to collapse or become concave (e.g., the textured portions  2204 A,  2204 B) may have a smaller wall thickness than other portions intended to substantially retain their shape (e.g., the untextured ends  2206 A,  2206 B). In other implementations, portions of the balloon intended to retain their shape may be selectively reinforced. For example, the balloon  2202  illustrated in each of  FIGS. 22A and 22B  includes internal ridges  2210 A,  2210 B disposed within the untextured ends  2206 A,  2206 B. During inflation and deflation, the internal ridges reinforce the untextured ends  2206 A,  2206 B such that the untextured ends  2206 A,  2206 B maintain a more consistent shape as compared to unreinforced portions of the balloon  2202 , such as the textured portion  2204 A,  2204 B. 
       FIG. 24  illustrates an alternative structure for controlling collapse of an example balloon  2402  during deflation. The balloon  2402  includes a pair of textured portions  2404 A,  2404 B between which are disposed untextured portions  2406 A,  2406 B. As illustrated, each of the textured portions  2404 A,  2404 B has a first wall thickness (t1) and each of the untextured portions  2406 A,  2406 B has a second wall thickness (t2) that is greater than the wall thickness of the textured portions  2404 A,  2404 B. In one example implementation, the first wall thickness may be from and including about 100 μm to and including about 2000 μm while the second wall thickness may be from and including about 150 μm to and including about 3000 μm. 
     As a result, as the balloon  2402  collapses, the textured portions  2404 A,  2404 B will collapse and become concave prior to and to a greater extent than the untextured portions  2406 A,  2406 B. In certain implementations, the wall thickness of the untextured portions  2406 A,  2406 B may also be sufficient to prevent or substantially reduce collapse of the untextured portions  2406 A,  2406 B during deflation. As further illustrated in  FIG. 24 , controlled collapse of the balloon may also be facilitated by the use of notches  2410 A- 2410 D or similar features that provide localized reduction of the wall thickness of the balloon  2402 . For example, the notches  2410 A- 2410 D of the balloon  2402  are formed at the transition between the textured portions  2404 A,  2404 B and the untextured portions  2406 A,  2406 B to facilitate collapse of the untextured portions  2406 A,  2406 B. 
     The specific ways in which balloons may be inflated/collapsed described above are provided merely as examples. More generally, balloons in accordance with the present disclosure may be configured to collapse and/or inflate in a non-uniform way. By doing so, different states of deflation/inflation may be used to disposed different proportions of the balloon protrusions at a maximum diameter of the balloon and/or to position different proportions of the protrusions in a substantially outwardly/radially extending direction. 
       FIGS. 2A-2AD  are various views of example protrusions in accordance with the present disclosure. These example protrusions are shown with the corresponding balloon in an unstrained state. Accordingly, inflation of the corresponding balloons into a strained state will generally alter the shapes of the example protrusions. 
       FIG. 2A  illustrates a first protrusion  200 A extending from the balloon  102  and having a cylindrical or rectangular shape,  FIG. 2B  illustrates a second protrusion  200 B having a triangular or pyramidal shape, and  FIG. 2C  illustrates a third protrusion  200 C having a rounded or hemispherical shape.  FIG. 2D  is a cross-sectional view of a fourth protrusion  200 D composed of multiple materials. 
     The protrusion shapes illustrated in  FIGS. 2A-2D  are intended merely as examples and other protrusion shapes are possible. For example and without limitation, other implementations of the current disclosure may include protrusions having any shape, including but not limited to rectangular, square, triangular, pentagonal, heptagonal, hexagonal, pyramidal, mushroom, or spherical shape. These protrusions are solid in one example, while in other embodiments the protrusions may be hollow. The ends of the protrusions distal to the surface of the balloon  102  may also be formed in various shapes. For example and without limitation, the distal ends of the protrusions may be flat, rounded (including either of convex or concave), pointed, or mushroomed. The width/diameter of the protrusions may also vary. For example, the distal end of the protrusions may be larger in diameter than the proximal end, so as to resemble a mushroom. In other implementations, the proximal end of the protrusions may be larger in diameter than the distal end, such that the protrusions distally taper. 
     As noted above,  FIG. 2D  illustrates a protrusion  200 D formed from multiple materials. More specifically, the protrusion  200 D includes a first portion  202 D proximal the balloon  102  and a second portion  204 D distal the balloon  102 . As illustrated, the first portion  202 D is integrally formed with the balloon  102 . The second portion  204 D, on the other hand, forms a cap or tip of the protrusion  200 D that may be coupled to or formed onto the first portion  202 D after formation of the first portion  202 D. In other implementations, each of the first and second portions  202 D,  204 D may be formed from different materials than the balloon  102 . 
     The specific arrangement illustrated in  FIG. 2D  is intended merely as an example of a multi-material protrusion and other arrangements are possible. For example and without limitation, multi-material protrusions may be formed by embedding or implanting structural elements of a first within protrusions formed of a second material or at least partially encompassing protrusions formed from a first material with a cap, sheath, or similar element formed from a second material. It should also be appreciated that while  FIG. 2D  illustrates a two-material protrusion  200 D, any suitable number of materials may be used to form protrusions in accordance with the present disclosure. 
       FIGS. 2E-2AD  illustrate additional example protrusions that may be implemented in embodiments of the present disclosure.  FIGS. 2E and 2F , for example, are a cross-sectional view and a plan view, respectively, of a protrusion  200 E extending from the balloon  102  and having a frustoconical shape. As illustrated in  FIG. 2E , the shape of the protrusion  200 E may be defined by a base diameter b, a height h, and a top diameter t of the protrusion  200 E. Although any suitable dimension for b and h may be used, in at least certain implementations, b may be from and including about 50 μm to and including about 3000 μm, h may be from and including about 25 μm to and including about 3000 μm, and t may be from and including about 25 μm to and including about 2500 μm. Moreover, while the protrusion  200 E of  FIGS. 2E and 2F  is illustrated as having a top  202 E extending substantially perpendicular to an axis  204 E of the protrusion  200 E, in other implementations, the top  202 E may instead be biased relative to the axis  204 E. The performance characteristics of the protrusion  200 E may be modified by altering various aspects of the protrusion  200 E. For example and without limitation, any of the base diameter, top diameter, or height of the protrusion  200 E may be varied to modify the stiffness of the protrusion  200 E. 
       FIGS. 2G-2N  illustrate various implementations of pyramidal protrusions. Specifically,  FIGS. 2G and 2H  are a cross-sectional view and a plan view, respectively, of a protrusion  200 G extending from the balloon  102  and having a pointed, square-based pyramid shape.  FIGS. 21 and 2J  are a cross-sectional view and a plan view, respectively, of a protrusion  200 J extending from the balloon  102  and having a truncated, square-based pyramid shape.  FIGS. 2K and 2L  are a cross-sectional view and a plan view, respectively, of a protrusion  200 K extending from the balloon  102  and having a truncated, square-based pyramid shape including a square recess  202 K extending into the protrusion  200 K from a top surface  204 K of the protrusion  200 K. Similarly,  FIGS. 2M and 2N  are a cross-sectional view and a plan view, respectively, of a protrusion  200 M extending from the balloon  102  and having a truncated, square-based pyramid shape including a concave top surface  202 M. 
       FIGS. 2O-2R  illustrated example protrusions having an asymmetrical or “swept” configuration. More specifically,  FIGS. 2O and 2P  are a cross-sectional view and a plan view of another example protrusion  2000 , the protrusion Q having a swept square-based pyramidal shape. Similarly,  FIGS. 2Q and 2R  are a cross-sectional view and a plan view of yet another example protrusion  200 Q, the protrusion  200 Q having a swept truncated conical shape. In certain implementations, such swept shapes may be the result of molding process limitations. For example, a mold for producing balloons in accordance with the present disclosure may be formed using electrical discharge machining (EDM). In such cases, a machining electrode is plunged into a mold half to form the protrusions. In applications in which the plunging path is linear and the mold half is curved, the resulting feature will inherently have a shadowed or swept shape. Nevertheless, in other implementations the swept shapes may be specifically controlled to provide improved traction, to otherwise bias the protrusions in a particular direction, to provide reinforcement in a specific direction, and the like. 
       FIG. 2S  is a cross-sectional view of still another example protrusion  200 S. The protrusion  200 S is provided to illustrate that protrusions in accordance with the present disclosure may be hollow. While illustrated in  FIG. 2S  as being substantially rectangular or cylindrical in shape, it should be understood that any protrusion design discussed herein may be at least partially hollow and such hollow protrusions are not limited to any specific shape or dimensions. 
       FIGS. 2T and 2U  are a cross-sectional view and a plan view of another example protrusion  200 T. More specifically, the protrusion  200 T has a tubular cylindrical shape and is intended to illustrate an implementation of a protrusion having a tubular or thin-walled construction. Although illustrated as having a cylindrical shape, it should be understood that thin-walled/tubular protrusions similar to that illustrated in  FIGS. 2T and 2U  are not limited to cylindrical shapes. Rather, thin-walled or tubular protrusions may have any suitable shape. 
       FIGS. 2V and 2W  are a cross-sectional view and a plan view of still another example protrusion  200 V. More specifically, the protrusion  200 V has a barbell-type shape and is intended to illustrate an implementation of a protrusion formed from a series of interconnected ribs, walls, or similar structures extending from the surface of the balloon  102 . 
       FIG. 2X  is a cross-sectional view of a protrusion  200 X having a jagged shape. Protrusion  200 X is intended to illustrate that protrusions in accordance with the present disclosure are not limited to conventional shapes or surfaces. Rather, protrusions may be implemented having any suitable shape or surface, including random or pseudo-randomly generated shapes or surfaces. 
       FIGS. 2Y-2AD  illustrate various protrusions having a directional design. For purposes of the present disclosure, directional protrusions refer to protrusions that are specifically shaped to provide reduced friction/adhesion or improved aero- or hydrodynamic behavior in a first direction and increased friction/adhesion or reduced aero- or hydrodynamic behavior in a second direction that is generally opposite the first direction. Among other things, such protrusions designs may be beneficial for facilitating translation or movement of a balloon within a lumen in a first direction while providing increased resistance to translation or movement of the balloon in a second opposite direction. 
     Referring first to  FIGS. 2Y and 2Z , a cross-sectional and a plan view of a first directional protrusion  200 Y is provided. The protrusion  200 Y has a swept or saw tooth shape that provides variable resistance in opposite directions. More specifically, the shallower slope of a leading face  202 Y of the protrusion provides reduced friction in a first direction a first direction (indicated by arrow A) as compared to a second, opposite direction (indicated by arrow B). In the specific implementation illustrated in  FIG. 2Y , a trailing face of the protrusion  204 Y is arranged such that the protrusion  200 Y forms a barb or hook-like shape. However, it should be appreciated that variable directional performance may be achieved with a less aggressive design, such as the “swept” protrusions illustrated in  FIGS. 2O-2R . 
       FIGS. 2AA and 2AB  are a cross-sectional view and a plan view of a second direction protrusion  200 AA having a semi-circular shape. More specifically, the protrusion  200 AA includes a curved leading surface  202 AA and a substantially flat tailing surface  204 AA such that the protrusion  200 AA provides reduced friction in a first direction (indicated by arrow A) as compared to a second direction (indicated by arrow B). Additional directional properties of the protrusion  200 AA are provided by including a rounded or smoothed leading edge  206 AA and a substantially sharper tailing edge  208 AA. For example, in at least certain implementations, the tailing edge  208 AA may have a radius from and including about 5 μm to and including about 500 μm, for example 75 μm, while the leading edge  206 AA may have a radius having that is 1.1-2.0 times or greater than the radius of the tailing edge  208 AA. 
       FIGS. 2AC and 2AD  are a cross-sectional view and a plan view of a third direction protrusion  200 AA having a scalloped crescent shape. More specifically, the protrusion  200 AC includes a convex leading surface  202 AC and a concave tailing surface  204 AC such that the protrusion  200 AC provides reduced friction in a first direction (indicated by arrow A) as compared to a second direction (indicated by arrow B). Similar to the protrusion  200 Y illustrated in  FIGS. 2Y and 2Z , the crescent shaped protrusion  200 AC is also “swept” to further vary resistance between the indicated directions. 
     It should be understood that the protrusions illustrated in  FIGS. 2A-2AD  and elsewhere throughout this disclosure are intended merely as examples and should not be viewed as limiting the scope of the present disclosure. Implementations of the present disclosure may include protrusions combining features or characteristics of any of the protrusion designs discussed herein. For example and without limitation, the concave tip illustrated in  FIGS. 2M and 2N  may be incorporated into protrusions having any suitable base shape. Similarly, “swept” protrusion designs, as illustrated in  FIGS. 2O-2R  may similarly include any suitable base shape. 
     While illustrated in  FIGS. 2A-2AD  as having substantially smooth exterior surfaces, in at least certain implementations, outer surfaces of protrusions in accordance with the present disclosure may instead be selectively roughened or textured to provide additional friction/adhesion. For example and without limitation, such texturing may be applied to the protrusions by grit blasting or otherwise roughening the surfaces of the mold used to produce the protrusions. In such implementations, such additional texturing or roughening of the protrusions surfaces may be about 25 μm or less. 
     The example balloon  102  illustrated in  FIGS. 1A-1E  included a textured portion  104  having a substantially uniform distribution of protrusions extending therefrom. In contrast,  FIG. 3  is a side elevation view of another example balloon  300  in accordance with the present disclosure in a minimally inflated state including a more complicated textured portion  304 . More specifically, in contrast to the textured portion  104  of the balloon  102  illustrated in  FIG. 1E , which included a substantially uniform pattern and distribution of substantially uniform protrusions, the textured portion  304  includes multiple areas  306 A- 312  of protrusions. More specifically, the textured portion  304  includes a first set of areas  306 A- 306 F having a relatively low protrusion density; a second set of areas  308 A,  308 B having a relatively high protrusion density; a third set of areas  310 A,  310 B having an intermediate protrusion density; and a fourth area  312  that is substantially smooth. Although the areas are described as having different protrusion densities, it should be appreciated that each area may vary in other aspects including, without limitation, one or more of protrusion density, protrusion shape, protrusion rigidity, protrusion distribution pattern, protrusion material, and the like. Similarly, as illustrated in  FIG. 3 , each area of the textured portion  304  may vary in size and shape. 
     Referring back to the example medical device  100  of  FIGS. 1A-1E , the height of the protrusions  106  may vary in different applications of the present disclosure. For example and without limitation, in at least one implementation the protrusions  106  may be from and including about 5 μm to and including about 700 μm tall when the balloon  102  is in either an uninflated or inflated state. In another implementation, the protrusions may be from and including about 15 μm to and including about 200 μm tall. In yet other implementations, the protrusions may be from and including about 30 μm to and including about 110 μm tall. In at least one specific implementation, the protrusions are from and including about 300 μm to and including about 500 μm to enable the protrusions to penetrate mucosal layers of the physiological lumen. In contrast, in applications in which a mucosal layer may not be present (e.g., cardiac applications), the protrusions may be from and including about 50 μm to and including about 100 μm in height. Although implementations of the present disclosure are not limited to any specific protrusion heights, in at least certain implementations, the protrusions may have an overall height up to and including about 5000 μm or greater. Specific implementations of the present disclosure may also include protrusions having varying heights. Also, individual protrusions may have different portions extending to different heights (e.g., having a crenellated or other top having varying height). 
     As noted above, protrusion height for a given application may vary depending on the type of physiological lumen within which a balloon is being deployed and, more specifically, the thickness of any fluid layers that may be present. For example and without limitation, the mucosal layer of the colon is generally around 800-900 μm thick while that of the ileum is generally around 400-500 μm thick. Accordingly, to adequately penetrate the respective mucosal layers, balloons intended for deployment in the colon may generally be provided with protrusions of greater length as compared to those of balloons intended for deployment in the ileum. Similar considerations may be made for fluidic layers (e.g., other forms of mucus, sinus fluid, perspiration, etc.) that may be present in other physiological lumens within which balloons according to the present disclosure may be deployed. 
     Similar to height, the cross-sectional width (e.g., the diameter in the case of protrusions having a circular or ovoid cross-section) of each protrusion may vary. For example and without limitation, in one implementation the protrusions have a cross-sectional width from and including about 5 μm to and including about 1000 μm when the balloon  102  is in either the uninflated or inflated state. In another implementation the protrusions have a cross-sectional width from and including about 25 μm to and including about 300 μm. In yet other embodiments the protrusions have a cross-sectional width from and including about 70 μm to and including about 210 μm. In still another implementation the protrusions have a cross-sectional width from and including about 600 μm to and including about 1000 μm. In yet another implementation the protrusions have a cross-sectional width from and including about 300 μm to and including about 500 μm. In another implementation, the protrusions have a cross-sectional width from and including about 150 μm to and including about 250 μm. In at least one specific implementation, the protrusions have a cross-sectional width of about 400 μm. Implementations of the present disclosure may also include protrusions having varying diameters. Also, individual protrusions may have different portions having different diameters (e.g., a tapering shape). Although protrusion cross-sectional width for implementations of the present disclosure are not limited to any particular ranges or values, in at least certain implementations, the protrusions may have an overall cross-sectional width up to and including about 5000 μm or greater. 
     In certain implementations, the overall proportions of a protrusion may instead be defined according to an aspect ratio relating the height of the protrusion to the cross-sectional width/diameter of the protrusion. Although any suitable aspect ratio may be used, in one example implementation, the aspect ratio is less than about 5. In another example implementation, the aspect ratio may be from and including about 0.05 to and including about 10. In yet another example implementation the aspect ratio may be from and including about 0.1 to and including about 5.0. In another example implementation the aspect ratio may be from and including about 0.5 to and including about 1.0. In still another example implementation, the aspect ratio may be from and including about 1.0 to and including about 10.0. In another implementation, the aspect ratio may be from and including about 0.1 to and including about 1. In still another implementation, the aspect ratio may be from and including about 1 to and including about 2. In yet another example implementation, the aspect ratio may be about 0.5, about 1.0, or about 2.0. It should also be appreciated that the aspect ratio for protrusions within a given implementation of the present disclosure may vary such that a first set of protrusions of a balloon conforms to a first aspect ratio while a second set of protrusions for the same balloon conforms to a second aspect ratio. Moreover the cross-sectional width/diameter of the protrusion for purposes of determining an aspect ratio may be any measure of cross-sectional width/diameter. For example, the cross-sectional width/diameter may be the maximum cross-sectional width/diameter of the protrusion, the minimum cross-sectional width/diameter of the protrusion, an average cross-sectional width/diameter of the protrusion, or the cross-sectional width/diameter of the protrusion at a particular location along the length of the protrusion. 
     The protrusions may also be configured to have a particular stiffness to avoid inadvertent bending or deformation while still allowing engagement of the protrusions with biological tissue. In at least certain implementations, the protrusions are formed such that they have a stiffness that is at least equal to the tissue with which the protrusions. For example, in certain implementations, the stiffness of the protrusions is from and including about 1.0 to and including 2.0 times that of the tissue with which it is to engage. The stiffness may also be expressed as a modulus of elasticity of the material from which the protrusions are formed. For example, in at least some implementations, the protrusions are formed from a material having a modulus of elasticity from and including about 50 kPa to and including about 105 kPa. In other implementations including stiffer protrusions, the protrusions may be formed of a material having a modulus of elasticity from and including about 0.8 MPa to and including about 2.0 MPa. 
     In certain implementations, protrusions of balloons in accordance with the present disclosure may be configured to deform in response to a strain being applied to the balloon. Such deformation may then be used to dynamically control and adjust traction between the balloon and biological tissue. 
       FIG. 4A  illustrates a portion of a balloon  402  or similar structure in a first state of strain. In certain applications, the first state of strain may correspond to an unstrained state or, alternatively, may correspond to a state in which a first strain is applied to the balloon  402 . As shown, the balloon  402  includes multiple protrusions, such as protrusion,  406  distributed across and extending from a surface  403  of the balloon  402 . As illustrated in  FIG. 4B , the protrusions  406  may, in certain implementations, have a frustoconical shape.  FIG. 5A  illustrates the portion of the balloon  402  in a second state of strain, in which a strain greater than that of the first state of strain is applied to the balloon  402 . As shown in  FIG. 5A , in at least some applications, the applied strain when in the second state of strain may be biaxial. Such strain may result, for example, from inflation of the balloon  402 . As illustrated in  FIG. 5A , the application of strain generally results in both the distance between adjacent protrusions increasing as well as a stretching/deformation of the protrusions.  FIG. 5B  is a cross-sectional view of the protrusion  406  when a biaxial strain is applied to the balloon  402 . As illustrated, the frustoconical shape of the protrusion  406  deforms under the biaxial strain. In particular, each of a top surface  408  and side wall  410  of the protrusion  406  become increasingly concave in response to the application of biaxial strain. 
     The term “biaxial strain” is generally used herein to refer to a strain applied along two axes which, in certain implementations, may be perpendicular to each other. In certain cases, the biaxial strain may be approximately equal along each axis. For example, strain applied to the balloon may be equal in each of a longitudinal direction and a transverse direction. However, in other implementations, strain may be applied unequally along the axes, including strain resulting in non-uniform deformation of the protrusions (e.g., elongation of compression primarily along a single axis). Moreover, sufficient deformation of the protrusions may also be achieved by application of a uniaxial strain or a multiaxial strain other than a biaxial strain. Accordingly, while the examples described herein are primarily discussed with reference to a biaxial strain resulting in variations in frictional and adhesive engagement resulting from deformation of the protrusion, implementations of the present disclosure are more generally directed to variations in frictional and adhesive engagement from deformation of the protrusions in response to any applied strain. 
       FIGS. 6A and 6B  are cross-sectional views of the protrusion  406  illustrating further details of the protrusion in a strained and unstrained state, respectively. As illustrated in  FIG. 6A , when in the unstrained state, the protrusion  406  has a top diameter (D1) corresponding to the top surface  408  of the protrusion and a base diameter (D2) corresponding to a base  412  of the protrusion  406 . The top surface  408  of the protrusion  406  is shown as being disposed at a maximum height (H). The top surface  408  is also shown as being concave and having a concavity defined by a radius of curvature (R). The top surface  408  of the protrusion reaches a height (H) relative to the surface  403  of the balloon  402 . It should be appreciated that while the top surface  408  of the protrusion is shown in  FIG. 6A  as being concave, in other implementations, the top surface  408  may be substantially flat. Also, while the top diameter D1 and base diameter D2 are illustrated in  FIG. 6A  as being different, in other implementations D1 and D2 may be equal such that the protrusion  406  is substantially cylindrical in shape. 
     As shown in  FIG. 6B , the protrusion  406  may deform in response to a strain applied to the balloon  402 . In particular, each of the top diameter (D1) and the base diameter (D2) may expand to a second base diameter (D1′) and a second base diameter (D2′), respectively. The radius of curvature (R) of the top surface  408  may also decrease to a second radius of curvature (R′), thereby causing the top surface  408  to become increasingly concave. In addition to the foregoing dimensional changes, the overall height of the protrusion  406  may change from the initial height (H) to a second height (H′). 
     As illustrated in  FIGS. 6A and 6B , in at least some implementations of the present disclosure, each protrusion may include a lip or edge  414  at the transition between the side wall  410  and the top surface  408 . In general, a relatively sharp lip or edge  414  may allow the protrusions to more readily engage the wall of the physiological lumen and may also facilitate penetration of mucosal or other layers that may be present on the wall. Accordingly, in at least some implementations, the edge  414  may have a radius of no more than about 3 μm. 
     The initial dimensions of the protrusion  406  may vary. For example, in certain implementations the unstrained upper diameter (D1) of the protrusion may be from and including about 100 μm to and including about 700 μm; the unstrained lower diameter (D2) of the protrusion may be from and including about 100 μm to and including about 750 μm; the unstrained height (H) of the protrusion may be from and including about 100 μm to and including about 700 μm; and the unstrained radius of curvature (R) of the top surface  408  of the protrusion may be from and including about 1 mm to and including about 2 mm. Similarly, in certain implementations, the strained upper diameter (D1′) of the protrusion may be from and including about 375 μm to and including about 750 μm; the strained lower diameter (D2′) of the protrusion may be from and including about 405 μm to and including about 825 μm; the strained height (H′) of the protrusion may be from and including about 200 μm to and including about 400 μm; and the strained radius of curvature (R′) of the top surface  408  of the protrusion may be from and including about 500 μm to and including about 750 μm. In one specific example, the D1 may be about 250 μm, D2 may be about 270 μm, H may be about 500 μm, and R may be about 1.5 mm. In the same example, the balloon  402  may be configured to be strained such that D1′ can be up to about 375 μm, D2′ can be up to about 400 μm; H′ may be decreased down to about 450 μm, and R′ may be decreased down to about 500 μm. In other implementations, deformation of the protrusion  406  in response to a strain applied to the balloon  402  may instead be based on a change in the surface area of the protrusion  406 . For example and without limitation, the balloon  402  may be configured such that the surface area of the protrusion  406  may increase up to about 25%. 
     During experimental testing, it was observed that separation force between a piece of material including protrusions similar to the protrusion  406  of  FIGS. 6A and 6B  and a flexible probe simulating biological tissue varied with the degree of biaxial stain applied to the material. More specifically, the probe was first made to contact the material sample, causing the probe to adhere to the material sample. The probe was then withdrawn from contact with the material sample. The force required to affect such separation was measured and observed to vary non-linearly with the degree of biaxial strain applied to the material sample. 
     As indicated in  FIG. 6A , the protrusion  406  may be further characterized by the sharpness of the edge  414  at the transition between the side wall  410  and the top surface  408  of the protrusion  406 . Although the edge  414  is not limited to specific degrees of sharpness, testing has indicated that particular sharpness ranges can be advantageous in fixing balloons in accordance with this disclosure within a physiological lumen, particular in the presence of mucus and other similar fluids that may be secreted or disposed along the inner surface of the physiological lumen. More specifically, sufficient sharpness of the edge  414  appears to facilitate penetration through layers of mucus (or similar fluids) to facilitate engagement between the balloon and inner wall of the lumen. Accordingly, in at least certain implementations, the edge  414  between the side wall  410  and the top surface  408  may have a radius from and including about 25 μm to and including about 500 μm, for example 75 μm. In other implementations, the radius is not greater than about 25 μm. 
       FIG. 7  is a graph  700  summarizing the experimental findings regarding the relationship between separation force and biaxial strain. More specifically, the graph  700  includes a first axis  702  corresponding to biaxial strain and a second axis  704  corresponding to the measured separation force when separating the probe and material sample. As indicated by line  706 , the separation force varied in a non-linear fashion in response to changes in biaxial strain. 
     The graph  700  further indicates a base separation force line  708  corresponding to the separation force when the material sample is unstrained. The graph further includes a “flat” separation force line  710  corresponding to a second material sample substantially similar to the tested material sample but lacking any protrusions. 
     As illustrated in the graph  700 , the separation force for the material having the protrusions may be varied to have a range of values by changing the biaxial strain applied to the material. For example, by applying no or relatively low biaxial strain, the material with protrusions may actually be made to have less separation force (i.e., be made to be less frictional and/or adhesive) than a flat sheet of the same material. However, as biaxial strain is increased friction and adhesion also increase such that, at a certain level of biaxial strain, the separation force of the material including protrusions may be made to exceed that of a flat sheet of the same material. 
     As shown in the graph  700 , this may, in certain implementations, reduce the separation force when unstrained as compared to separation force of a flat material sheet. However, as strain is increased, the separation force may increase above that of the flat sheet. In other words, by selectively applying biaxial strain to the material sample, separation force may be varied, providing physicians with increased control and more reliable engagement for medical devices incorporating balloons in accordance with the present disclosure. 
     The specific example discussed in  FIGS. 4A-7  generally includes protrusions having a flat or partially concave top surface that, when a strain is applied, causes the protrusions to become increasingly concave, thereby increasing their surface area. In other implementations of the present disclosure, the protrusions may instead include a rounded/convex or similar top surface such that when a strain is applied, the top surfaces of the protrusions at least partially flatten. Such flattening may result in a reduction of the surface area and, as a result, a change (generally a reduction) in the separation force between the protrusions and the physiological lumen. Accordingly, whereas in the previous examples a strain is applied to increase protrusion surface area to increase separation force, strain may also be used to decrease protrusion surface area and, as a result, decrease separation force. In either case, however, strain is used as the primary mechanism for altering the shape and the result separation force of the protrusions. 
     The separation force between the balloon and the physiological lumen may vary across different implementations of the present disclosure and across different states of inflation for any given implementation. However, in at least some implementations, the balloon may be configured to have a separation force less than about 5 N when the balloon is in its deflated state (e.g., as illustrated in  FIGS. 1A-1B ) to facilitate translation of the balloon along the physiological lumen with minimal adhesion and friction. In other implementations, the separation force when in the deflated state may be less than about 3 N. In a specific example, the separation force in the deflated state may be about 1 N. The balloon may also be configured to have a particular separation force in a minimally inflated state in which the balloon substantially engages the physiological lumen. For example, in at least some implementations, the separation force in the minimally inflated state may be from and including about 10 N to and including about 30 N. In other implementations, the separation force in the minimally inflated state may be from and including about 15 N to and including about 25 N. In one specific implementation, the separation force in the minimally inflated state may be about 20 N. 
     As previously discussed, in at least some implementations, a strain on the balloon may be applied or modified (e.g., by inflating or deflating the balloon) to modify the adhesive and frictional characteristics of the balloon and, as a result, the separation force between the balloon and physiological lumen. In one implementation, the separation force relative to a minimally inflated state may be reduced to 1% or lower by deflating the balloon and up to and including 200% by overinflating and straining the balloon. In another implementation, the deflated balloon may have a separation force of less than about 5% of the minimally inflated state and a maximum of about 150% by straining the balloon. In still another example implementation, the balloon may have a lower bound separation force of less than about 5% of the minimally inflated state and a maximum of about 125% by straining the balloon. Accordingly, in at least one specific example, the balloon may have a separation force of about 20 N in the inflated state, about 1 N in the deflated state, and about 25 N in a maximum strained state. 
     As previously noted, balloons in accordance with the present disclosure may be manufactured in various ways. For example, in at least one implementation, balloons including protrusions as discussed above may be manufactured through a casting process.  FIG. 8  illustrates an example mold  800  for use in such a casting process. As illustrated the mold  800  includes an outer mold piece  802  within which an inner mold piece or core  804  is disposed. The combination of the outer mold piece  802  and the core  804  defines a cavity  806  providing the general shape of the balloon to be molded. 
     In addition to the outer mold piece  802  and the core  804 , the mold  800  includes an insert  808  for forming protrusions on the balloon during casting. The insert  808  is separately formed to have the pattern and distribution of protrusion to be included on the final balloon. The insert  808  may be manufactured in various ways including, without limitation, machining, 3D printing, microlithography, or any other similar manufacturing process. Once formed, the insert  808  may be disposed within and coupled to the outer mold piece  802 . In certain implementations, the insert  808  may be formed from a semi-rigid material such as, but not limited to, Kapton® or other polyimide material, silicone, latex, or rubber. 
     During the casting process, balloon material (such as but no limited to ECOFLEX® 50) is poured into the cavity and allowed to set. In certain implementations, a vacuum is also applied to the mold  800  to remove air from the mold cavity  806  and to facilitate the material poured into the cavity  806  to take on the shape of the mold cavity  806 , including the protrusions defined by the mold insert  808 . 
     In certain implementations, the overall thickness of the balloon may be modified by changing the thickness of the cavity  806 . For example, the outer mold piece  802  may be configured to receive cores of varying sizes such that the thickness of the cavity  806  defined between the outer mold piece  802  and the core  804  may be modified by swapping cores into the mold  800 . 
     Although illustrated in  FIG. 8  as having a substantially uniform width, the cavity  806  defined between the outer mold piece  802  and the core  804  may also be non-uniform such that the cavity  806  is wider at certain locations within the mold  800 . Accordingly, any balloon formed using the mold  800  will have corresponding variations in its thickness. By varying the thickness of the balloon, various characteristics may be imparted to the balloon. For example, the thickness of certain locations of the balloon may be increased to improve the overall durability and strength of the locations. In other cases, the thickness of the balloon may be varied such that reinforced regions of the balloon are formed that cause the balloon to collapse and/or expand in a particular way. Such reinforced regions may also cause the balloon to assume a particular shape in any of a deflated state, partially inflated state, or fully inflated state. 
       FIG. 9  is an isometric view of an alternative mold  900  for use in manufacturing balloons in accordance with the present disclosure. The mold  900  includes an outer mold piece  902  within which an inner mold piece or core (not shown) may be disposed. In contrast to the mold  800  of  FIG. 8  in which a removable insert  808  is used to form the balloon protrusions, the outer mold piece  902  includes voids  906  formed directly into an inner surface  908  of the outer mold piece  902  that are used to form the protrusions during the casting process. 
     As discussed above, in at least some implementations, balloons in accordance with the present disclosure may be formed using a casting process. Such casting processes may include piece casting, slush casting, drip casting, or any other similar casting method suitable for manufacturing a hollow article. In a slush casting process, for example, an amount of material may be added to the mold and slushed to coat the internal surface of the mold prior to the material setting. Other fabrication methods may also be implemented including, without limitation, various types of molding (e.g., injection molding) and extrusion processes. 
     While previous fabrication methods included integrally forming the protrusions with the balloon, in other implementations the protrusions may instead be formed onto a previously formed balloon. For example, in at least one other fabrication method, a base balloon may first be formed. The protrusions may then be formed or coupled to the balloon using a subsequent process. In one example fabrication method, the base balloon is extruded and then the protrusions are then added to the base balloon using a spray method. In another example fabrication method, the base balloon is formed using a first casting or molding process and, once the base balloon is set, a second casting or molding process (e.g., an over-molding process) is applied to form the protrusions on the exterior surface of the base balloon. 
     As previously discuss in the context of  FIGS. 1A-1E , balloons in accordance with the present disclosure may be implemented for use in various medical devices.  FIGS. 10-16  are schematic illustrations of various example medical devices and configurations of such medical devices including balloons of the present disclosure. It should be appreciated that the medical devices provided are merely example devices and are therefore non-limiting. More generally, balloons in accordance with the present disclosure may be used in conjunction with any medical device adapted to be inserted into a physiological lumen. In certain implementations, the medical device may include a lumen running its length. The device lumen may serve as a tool or catheter port such that tools and/or catheters can be threaded down the length of the medical device and out of a distal end of the device. Alternatively, the device may be threaded onto tools or catheters already disposed within the physiological lumen. 
       FIG. 10  is a schematic illustration of a first medical device  1000  in the form of a catheter delivery tool. As illustrated, the medical device  1000  includes a proximal hub  1004  from which each of a catheter tool channel  1006  and a balloon insufflation channel  1008 . A distal portion  1010  of the catheter tool channel  1006  extends from the hub  1004  and includes a balloon  1002  that may be selectively inflated and deflated by providing air to or allowing air to escape from the balloon  1002  via the balloon insufflation channel  1008 , respectively. Accordingly, the distal portion  1010  may be inserted into a physiological lumen of a patient with the balloon deflated. Once located at a point of interest within the physiological lumen, air may be provided to the balloon  1002  via the balloon insufflation channel  1008  to cause the balloon  1002  to expand and engage the wall of the physiological lumen. When so engaged, the catheter tool channel  1006  may be used to provide a clear and direct pathway to the location of interest. 
     The medical device  1000  is described above as being used in conjunction with or to guide a catheter or guide wire within the physiological lumen; however, in other implementations of the present disclosure, balloons in accordance with the present disclosure may be incorporated into catheters or guide wires. For example and without limitation in at least one implementation of the present disclosure an inflatable balloon as described herein may be disposed along a guide wire or catheter (e.g., at or near distal end of the guide wire or catheter). In such implementations, the guidewire or catheter may be inserted into a physiological lumen with the balloon in the deflated state. The balloon may be subsequently inflated to engage the physiological lumen and at least partially anchor the guide wire or catheter within the physiological lumen. 
       FIG. 11  is a schematic illustration of a second medical device  1100 , which may be an endoscopic tool. The second medical device  1100  includes an endoscope body  1104  that may include, for example and without limitation, a light emitting diode (LED)  1106  and a camera  1108 . The endoscope body  1104  may also define a catheter channel  1109  through which a catheter  1110  may be inserted. As illustrated in  FIG. 11 , the catheter  1110  may include a distal balloon  1102  that may be used to at least partially secure the catheter  1110  within a physiological lumen. 
     In one example application of the medical device  1100 , the catheter  1110  may be used as a guide for the endoscope body  1104 . More specifically, during a first process the catheter  1110  may be delivered to a point of interest along a physiological lumen with the balloon  1102  in an uninflated state. Once located, the balloon  1102  may be inflated to engage the balloon  1102  with the lumen and at least partially secure the catheter within the lumen. The endoscope body  1104  may then be placed onto the catheter  1110  such that the endoscope body  1104  may be moved along the catheter  1110 , using the catheter as a guide. 
       FIG. 12  is a schematic illustration of a third medical device  1200 . Similar to the medical device  1100  of  FIG. 11 , the medical device  1200  includes an endoscope body  1204  (or body of a similar tool) that may be configured to receive a catheter  1210 . However, in contrast to the medical device  1100  of  FIG. 11  in which the balloon  1102  was coupled to the catheter  1110 , the medical device  1200  includes a balloon  1202  coupled to the endoscope body  1204  and which may be used to at least partially secure the endoscope body  1204  within a physiological lumen of a patient. 
       FIG. 13  is a schematic illustration of a fourth medical device  1300  that combines aspects of both the medical device  1100  of  FIG. 11  and the medical device  1200  of  FIG. 12 . More specifically, the medical device  1300  includes an endoscope body  1304  that defines a catheter channel  1309  through which a catheter  1310  may be inserted. Like the medical device  1100  of  FIG. 11 , the catheter  1310  includes a distal balloon  1302  that may be used to at least partially secure the catheter  1310  within a physiological lumen. Also, like the medical device  1200  of  FIG. 12 , the endoscope body  1304  also includes a balloon  1312 . 
     The two-balloon configuration of the medical device  1300  may be used to progress the medical device  1300  along the physiological lumen. For example,  FIG. 17  provides a series of illustrations depicting progression of the medical device  1300  along a physiological lumen  1702  (indicated in Frame 1). As illustrated, the medical device  1300  may first be inserted into the physiological lumen in an uninflated/disengaged configuration (Frame 1). The endoscope balloon  1312  may then be inflated to engage the balloon  1312  with the lumen  1702  and to at least partially secure the endoscope body  1304  within the lumen  1702  (Frame 2). With the endoscope body  1304  secured, the catheter  1310  may then be extended from the endoscope body  1304  along the lumen (Frame 3) and the catheter balloon  1302  may be engaged with the lumen  1702  at a second location by inflating the catheter balloon  1302  at the second location (Frame 4). The balloon  1312  may then be deflated (Frame 5) and the endoscope body  1304  may be progressed along the lumen  1702  using the anchored catheter  1310  as a guide (Frame 6). When the endoscope body  1304  reaches the catheter balloon  1302 , the endoscope body  1304  may again be secured within the lumen  1702  by inflating the balloon  1312  (Frame 7). As illustrated in Frames 8-12, this process may be repeated to progress the medical device  1300  along the physiological lumen  1702 . 
     In certain implementations, the medical device may be a double balloon endoscope comprising a flexible overtube, as described in PCT Application Publication WO 2017/096350, wherein at least a portion of the outer surface of one or both of the first and second inflatable balloons includes a micro-patterned surface as described herein. In other embodiments, the endoscope does not include an overtube. 
       FIGS. 14-16  illustrate additional variations of the foregoing example medical devices.  FIG. 14  is a schematic illustration of a medical device  1400  in which a balloon  1402  is coupled to an overtube  1414  through which an endoscope device  1404  may be inserted.  FIG. 15  is a schematic illustration of a medical device  1500  similar to that of  FIG. 14  in that it includes a balloon  1502  coupled to an overtube  1514  through which an endoscope body  1504  extends. In addition to the balloon  1502 , the medical device  1500  includes a catheter balloon  1512  coupled to a distal end of a catheter  1510  extending through the endoscope body  1504 . An example double balloon endoscope device similar to that of  FIG. 15  and including a flexible overtube is described in detail in PCT Application Publication WO 2017/096350, which is incorporated herein by reference in its entirety. Finally,  FIG. 16  is another schematic illustration of a medical device  1600  including three distinct balloons. Specifically, the medical device  1600  includes a first balloon  1602  coupled to an overtube  1614 , a second balloon  1616  coupled to an endoscope body  1604  extending through the overtube  1614 , and a third balloon  1618  coupled to a catheter  1610  extending from the endoscope body  1604 . 
     In each of the medical tools, it is assumed that the described devices include suitable channels for delivering air or other fluid to the disclosed balloons to inflate the balloons and for removing air/fluid from the balloons to deflate the balloons. For example, each device may include a proximal manifold or coupling that may be connected to a pump or other fluid supply and that further includes a vent or return channel through which fluid may be removed from the balloons. In certain implementations, the medical device includes tubing that is in fluidic communication with one or more balloons of the device, the tubing allowing for controlled inflation and/or deflation of one or more of the balloons. In implementations in which the medical device includes multiple balloons, the tubing used to inflate one or more of the multiple balloons. Alternatively, different sets of tubing may be used to independently control inflation and deflation of respective subsets of the balloons of the medical device. 
     It should also be appreciated that in implementations of the present disclosure having multiple balloons, only one balloon need to have protrusions in accordance with the present disclosure. In other words, medical devices in accordance with the present disclosure my include one textured balloon as described herein, but may also include any number of non-textured balloons or balloons having designs other than those described herein. Moreover, while the example medical devices of  FIGS. 10-17  illustrate balloons located near the distal end of components of the medical devices (e.g., catheters, endoscope bodies, overtubes), in other implementations, balloons may be disposed at any location along such components, including at multiple locations along a given component. 
     The current disclosure further provides methods of performing endoscopy or similar medical procedures within a body cavity.  FIG. 18  is a flowchart illustrating an example method  1800  of such procedures which may be generally performed using medical devices in accordance with the present disclosure, including but not limited to the medical devices discussed in the context of  FIGS. 1A-1E and 10-17 . 
     At operation  1802 , the medical device is introduced into a physiological lumen or body cavity at least with a balloon of the medical device in a deflated state. As previously discussed, in at least one application of the present disclosure, the physiological lumen may include (but is not limited to) a portion of a patient&#39;s GI tract. For example, in the context of a small bowel endoscopy, the physiological lumen may correspond to a portion of a patient&#39;s lower digestive system and the medical device may include distal components, such as a light and/or camera, adapted to facilitate examination of the physiological lumen. 
     Once inserted into the physiological lumen, at least a portion of the medical device is translated along the physiological lumen to an engagement location while the balloon is in the deflated state (operation  1804 ). For example, in certain implementations, the portion of the medical device may be a catheter including the balloon and translating the portion of the medical device may include extending the catheter and balloon along the physiological lumen while a second portion of the medical device (e.g., an endoscope body) remains at the initial insertion location. In another example implementation, translating the portion of the medical device may include moving an endoscope or similar portion of the medical device along a guide wire or catheter extending along the physiological lumen. 
     Following translation of the portion of the medical device, the balloon of the medical device is inflated such that protrusions of the balloon as described herein engage with the wall of the physiological lumen (operation  1806 ). 
     Once at least partially secured within the lumen, the medical device may be manipulated to perform various functions (operation  1808 ). In one example, the secured portion of the medical device may include a catheter and the medical device may be manipulated by translating an unsecured portion of the medical device along the physiological lumen using the secured catheter as a guide. In another implementation, the medical device may be manipulated to remove a foreign object or tissue from the physiological lumen. For example, manipulation of the medical device may include insertion and operation of one or more tools of the medical device configured to capture, excise, ablate, biopsy, or otherwise interact with tissue or objects within the physiological lumen. In one specific example, the balloon may be disposed distal a foreign object or tissue of interest within the lumen during operation  1804 . The balloon may then be inflated in operation  1806  to obstruct the lumen. In one implementation, the balloon may then be moved proximally through the lumen to remove the foreign object. In another implementation, the balloon may instead be disposed within the lumen and moved distally to remove a foreign object distal the balloon. In another implementation, tools may be inserted through the medical device such that the tools may be used in a portion of the lumen proximal the inflated balloon. The foregoing examples may be useful for removing kidney stones from urinary ducts, removing gall stones from bile ducts, or clearing other foreign or undesirable matter present within the physiological lumen. 
     In another example medical procedure, a second balloon in accordance with the present disclosure may be disposed and inflated within the physiological lumen such that the protrusions of the second balloon partially engage the wall of the physiological lumen but otherwise remains at least partially movable within the physiological lumen. For example, the second balloon may be disposed on a guide wire or catheter that is then inserted through a medical device previously disposed within the physiological lumen (e.g., during operations  1804  and  1806 ). With the protrusions of the second balloon partially engaged, the second balloon may be translated along the physiological lumen to rub or scrape the wall of the physiological lumen. 
     Following manipulation of the medical device, the balloon is deflated to disengage the balloon from the physiological lumen (operation  1810 ) and an evaluation is conducted to determine when the medical procedure is complete (operation  1812 ). If so, the medical device is removed from the physiological lumen (operation  1814 ). Otherwise, the medical device may be repositioned within the physiological lumen for purposes of conducting any additional steps of the procedure (e.g., by repeating operations  1804 - 1812 ). 
       FIG. 19  is a second flowchart illustrating a method  1900  of modifying engagement between a balloon in accordance with the present disclosure and a physiological lumen. As previously discussed in the context of  FIGS. 4A-7 , the protrusions of balloons in accordance with the present disclosure may be configured to have adhesive and frictional properties that vary based on the biaxial strain applied to them. More specifically, applying strain to the balloon (e.g., by selectively inflating or deflating the balloon) causes deformation of the protrusions on the balloon&#39;s surface which in turn modifies adhesion and friction between the balloon and adjacent tissue. As previously discussed, by modifying the strain applied to the balloon, the adhesive and frictional properties may be dynamically manipulated by a physician to allow for improved control and flexibility during medical procedures. 
     With the foregoing in mind, the method  1900  begins with disposing a balloon having protrusions in accordance with the present disclosure within a physiological lumen (operation  1902 ). At operation  1904 , a biaxial strain is applied to the balloon, such as by inflating the balloon, such that protrusions of the balloon interact with a wall of the physiological lumen and have a first separation force with the wall. At operation  1906  the biaxial strain is modified such that a second separation force different from the first separation force is achieved between the balloon and the wall of the physiological lumen. 
     With respect to the foregoing, modifying the biaxial strain in operation  1906  may include either of increasing or decreasing the biaxial strain on the balloon. Increasing the biaxial strain may include, for example, inflating the balloon beyond the extent to which the balloon was inflated during operation  1904 . As discussed in the context of  FIG. 7 , increasing strain on the balloon in such a manner may generally result in an increase in the force required to separate the balloon from the wall of the physiological lumen (i.e., increase friction and/or adhesion). Decreasing the biaxial strain may include, for example, at least partially deflating the balloon to decrease the force required to separate the balloon from the wall of the physiological lumen (i.e., decrease friction and/or adhesion). 
       FIGS. 25A-25D  illustrate one example implementation of a balloon  2500  in accordance with the present disclosure in an unstrained state. More specifically,  FIG. 25A  is an isometric view of the balloon  2500 ,  FIG. 25B  is a plan view of the balloon  2500 ,  FIG. 25C  is an end view of the balloon  2500 , and  FIG. 25D  is a cross-sectional view of a textured surface of the balloon  2500 . 
     Referring first to  FIGS. 25A-25C , the balloon  2500  includes an elongate body  2502  extending along a longitudinal axis  2555 . The elongate body  2502  generally includes a middle portion  2504  and tapering end portions  2506 A,  2506 B, each of which terminates in a respective annulus  2507 A,  2507 B. The middle portion  2504  of the balloon  2500  includes oppositely disposed textured portions  2508 A,  2508 B. Extending between the textured portions  2508 A,  2508 B are untextured portions  2510 A,  2510 B. In other implementations, the surface of the middle portion  2504  of the balloon  2500  may be divided into more than two textured portions and/or more than two untextured portions. Similarly, balloons in accordance with the present disclosure may include only one textured portion. 
     As best seen in  FIG. 25B , the textured portions  2508 A,  2508 B of the balloon  2500  include uniformly distributed longitudinal rows of protrusions (e.g. protrusions rows  2512 ). As discussed below in further detail, the protrusions of the balloon  2500  have a truncated cone shape, although other protrusion shapes may be used in other implementations. Also, as visible in  FIG. 25B , adjacent rows of protrusions of the balloon  2500  are offset relative to each other such that every other row is aligned. In other implementations other row configurations may be implemented. For example, all rows may be aligned or multiple offsets may be used between different pairs of rows. 
     In at least certain implementations, the frictional and adhesive properties of the protrusions within a given row may vary based on the longitudinal spacing between the protrusions. For example, if spacing between protrusions is relatively narrow (e.g., from around 25 μm to around 400 μm, or from around 5% to 50% of the width of the protrusions), traction in a collapsed or unstrained state is generally reduced as compared to implementations including wider spacing. Testing suggest that such variable traction is the result of narrowly spaced protrusions in a given row more closely approximating the drag and traction provided by a continuous structure (e.g., a rib) as opposed to a series of independent protrusions. For example, during certain tests, it was observed that when in a partially deflated state, traction for a given balloon having twenty rows of approximately forty protrusions each approximated the traction provided by twenty continuous ribs extending along the length of the balloon. However, as the spacing between the protrusions was increased (e.g., by inflating and expanding the balloon) traction was observed to increase significantly. Among other things, the increase in traction was attributable to substantially all of the leading edges of the  400  protrusions being exposed and able to fully engage and interact with the inner wall of the physiological lumen when in the expanded state as compared to when the protrusions were more closely spaced. 
     The protrusions are configured such that when in a partially inflated state, each protrusion of each respective textured portion  2508 A,  2508 B extends in a common transverse direction relative to the longitudinal axis. In other words, the protrusions of the textured portion  2508 A extend parallel to each other in a first transverse direction while the protrusions of the textured portion  2508 B extend parallel to each other in a second transverse direction that is opposite the first lateral direction. In other implementations, the textured portions  2508 A,  2508 B may not be oppositely disposed but nevertheless including protrusions that extend in respective transverse directions. 
     As shown in  FIG. 25C , the textured portions  2508 A,  2508 B and the untextured portions  2510 A,  2510 B collectively extend around the circumference of the middle portion  2504  of the balloon  2500 . In the particular example illustrated in  FIG. 25C , each textured portion  2508 A,  2508 B extends around about a third of the surface of the middle portion  2504 , while the remaining third of the surface is divided between the untextured portions  2510 A,  2510 B. It should be appreciated, however, that the distribution of the textured and untextured portions of the balloon  2500  may vary from that which is illustrated in  FIGS. 25A-D . 
     As previously noted, each of the tapering end portions  2506 A,  2506 B terminate in a respective annulus  2507 A,  2507 B. In general, each annulus  2507 A,  2507 B is sized and shaped to be fit onto an overtube, catheter, endoscope, or similar tool. Accordingly, the shape and dimensions of each annulus  2507 A,  2507 B may vary depending on the specific tool onto which the balloon  2500  is to be disposed. However, in at least certain implementations, each annulus  2507 A,  2507 B may be reinforced relative to other portions of the balloon  2500  that are intended to expand. For example, in certain implementation, the wall thickness of each annulus  2507 A,  2507 B may be from and including about 1.25 times to and including about 5 times thicker than the wall thickness of the rest of the balloon  2500 . Among other things, thickening each annulus  2507 A,  2507 B facilitates improved retention of the balloon  2500  on an overtube or other tool, particularly when the balloon  2500  is subjected to inflation and deflation. 
     As illustrated in  FIG. 25C , in at least certain implementations, the height of each protrusion may be defined such that each protrusion extends to a common radius. For example, protrusion  2514  has a height such that a center of the tip of the protrusion  2514  extends to a radius r1 while protrusion  2516  has a height such that a center of the tip of the protrusion  2516  extends to a radius r2 that is substantially the same as the radius r1 of protrusion  2514 . An alternative interpretation of this approach to determining protrusion heights is that each protrusion extends from the surface of the balloon  2500  such that the midpoint of a top surface of each protrusion lies on a common circle. 
     Referring now to  FIG. 25D , a partial cross-sectional view of the middle portion  2504  of the balloon  2500  is provided to illustrate further details of the protrusions of the textured portions  2508 A,  2508 B. In the particular illustrated design, each protrusion (e.g. protrusions  2550 A- 2550 E) of the balloon  2500  has a truncated conical shape. While illustrated as having flat tops, in at least certain implementations, the top surface of each protrusion may instead be concave, as previously discussed herein. 
       FIG. 25D  illustrates an alternative approach to selecting the height of each protrusion. More specifically, in at least certain implementations, the height of protrusions in each row may be selected such that there is a predetermined height difference between adjacent rows. For example,  FIG. 25D  includes a dimension 61 corresponding to the difference in height between adjacent rows. As illustrated, 61 may be maintained between successive pairs of adjacent rows such that the top surfaces of the protrusions in adjacent rows descend in a step-like manner. Alternatively, 61 may differ between adjacent rows. Although various values of 61 may be used in implementations of the present disclosure, in at least certain implementations 61 may be from and including about 5 μm to and including about 3 mm. The foregoing approach may be used as an alternative to the previously discussed approach in which each protrusion extends such that a midpoint of its tip is at a common radius or lies on a common circle. 
     Although the specific dimensions of the balloon  2500  may vary based on the particular application of the balloon  2500 , in at least certain implementations, the balloon  2500  may have an overall length from and including about 10 mm to and including about 100 mm. In such implementations, the middle portion  2504  of the balloon may be from and including about 5 mm to and including about 90 mm and the end portions  2506 A,  2506 B may each be from and including about 2 mm to and including about 10 mm. The middle portion  2504  may also have a resting/partially inflated diameter from and including about 2 mm to and including about 50 mm, with the diameter corresponding to the surface of the middle portion  2504  from which the protrusions extend. The middle portion  2504  may also have a wall thickness from and including about 100 μm to and including about 3000 μm. Further in such implementations, each annulus  2507 A,  2507 B may have an outer diameter from and including 1 mm to and including 20 mm and a wall thickness from and including 100 μm to and including 5000 μm. The foregoing dimensions should be understood to be merely examples and designs in which the foregoing dimensions fall below or exceed the specified ranges should still be regarded as being within the scope of this disclosure. 
     Referring next to  FIGS. 26A-26D , a second balloon  2600  in an unstrained state is provided. Similar to the previously disclosed balloon  2500 , the balloon  2600  includes an elongate body  2602  extending along a longitudinal axis  2655 , the elongate body including a middle portion  2604  and tapering end portions  2606 A,  2606 B. Each of the end portions  2606 A,  2606 B similarly terminates in a respective annulus  2607 A,  2607 B for coupling the balloon  2600  to an overtube or similar tool. The middle portion  2604  of the balloon  2600  also includes oppositely disposed textured portions  2608 A,  2608 B and untextured portions  2610 A,  2610 B extending therebetween. 
     As best seen in  FIG. 26B , the textured portions  2608 A,  2608 B of the balloon  2600  include uniformly distributed rows of protrusions  2612 . In contrast to the truncated cone protrusions of the balloon  2500  discussed above, the protrusions of the balloon  2600  have a truncated pyramidal shape. Also, as shown in  FIG. 26B , adjacent rows of protrusions of the balloon  2600  are aligned relative to each other, as compared to the offset configuration of the balloon  2500  and adjacent protrusions within a given row of the balloon  2600  are sized and shaped such that they contact each other. This in contrast to the rows of the balloon  2500  in which adjacent protrusions in a row were spaced apart. 
     Like those of the balloon  2500 , the protrusions  2612  of the balloon  2600  are configured such that when in a partially inflated state, each protrusion of each respective textured portion  2608 A,  2508 B extends in a lateral direction relative to the longitudinal axis. In other words, the protrusions of the textured portion  2608 A extend in a first lateral direction while the protrusions of the textured portion  2608 B extend in a second lateral direction that is opposite the first lateral direction. 
     Referring now to  FIG. 26D , a partial cross-sectional view of the middle portion  2604  of the balloon  2600  is provided to illustrate further details of the protrusions of the textured portions  2608 A,  2608 B (e.g., protrusions  2650 A- 2650 E). As previously noted the protrusions  2650 A- 2650 E have a truncated square-based pyramid shape having a flat top. Nevertheless, the top surface of each protrusion may instead be concave, as previously discussed herein. Like the protrusions of the balloon  2500 , adjacent rows of the protrusions of the balloon  2600  may be configured such that the change in height (indicated as δ2) between adjacent rows of protrusions may be from and including about 5 μm to and including about 3 mm. Alternatively, and as described above in the context of  FIG. 25C , each protrusion may have a height such that a midpoint of a tip of each protrusion extends to a common radius/lies on a common circle. 
     Although the specific dimensions of the balloon  2600  may vary based on the particular application of the balloon  2600 , in at least certain implementations, the balloon  2600  may have an overall length from and including about 10 mm to and including about 100 mm. In such implementations, the middle portion  2604  of the balloon may be from and including about 5 mm to and including about 90 mm and the end portions  2606 A,  2606 B may each be from and including about 2 mm to and including about 10 mm. The middle portion  2604  may also have a resting/partially inflated diameter from and including about 2 mm to and including about 50 mm, with the diameter corresponding to the surface of the middle portion  2604  from which the protrusions extend. The middle portion  2604  may also have a wall thickness from and including about 100 μm to and including about 3000 μm. Further in such implementations, each annulus  2607 A,  2607 B may have an outer diameter from and including 1 mm to and including 20 mm and a wall thickness from and including 100 μm to and including 5000 μm. The foregoing dimensions should be understood to be merely examples and designs in which the foregoing dimensions fall below or exceed the specified ranges should still be regarded as being within the scope of this disclosure. 
     Referring next to  FIGS. 27A-27D , a third balloon  2700  in an unstrained state is provided. Similar to the previously disclosed balloons, the balloon  2700  includes an elongate body  2702  extending along a longitudinal axis  2755 , the elongate body including a middle portion  2704  and tapering end portions  2706 A,  2706 B. Each of the end portions  2706 A,  2706 B terminates in a respective annulus  2707 A,  2707 B for coupling the balloon  2700  to an overtube or similar tool. The middle portion  2704  of the balloon  2700  includes oppositely disposed textured portions  2708 A,  2708 B and untextured portions  2710 A,  2710 B extending therebetween. 
     The textured portions  2708 A,  2708 B of the balloon  2700  include uniformly distributed rows of protrusions  2712  and, more specifically, pyramidal protrusions. Similar to the rows of protrusions of the balloon  2600 , the rows of protrusions  2712  of the balloon  2700  are aligned relative to each other and adjacent protrusions within a given row of the balloon  2700  are sized and shaped such that they contact each other. However, in contrast to the previous two example balloons  2500 ,  2600 , the protrusions  2712  of the balloon  2700  are configured such that when in a partially inflated state, each protrusion of each respective textured portion  2708 A,  2708 B extends radially. 
     Referring now to  FIG. 27D , a partial cross-sectional view of the middle portion  2704  of the balloon  2700  is provided to illustrate further details of the protrusions of the textured portions  2708 A,  2708 B. As previously noted the protrusions (e.g., protrusions  2750 A- 2750 D) have a pyramidal shape; however, the pyramidal shaped protrusions may have any other suitable shape discussed herein, including shapes having concave top surfaces. 
     Although the specific dimensions of the balloon  2700  may vary based on the particular application of the balloon  2700 , in at least certain implementations, the balloon  2700  may have an overall length from and including about 10 mm to and including about 100 mm. In such implementations, the middle portion  2704  of the balloon may be from and including about 5 mm to and including about 90 mm and the end portions  2706 A,  2706 B may each be from and including about 2 mm to and including about 10 mm. The middle portion  2704  may also have a resting/partially inflated diameter from and including about 2 mm to and including about 50 mm, with the diameter corresponding to the surface of the middle portion  2704  from which the protrusions extend. The middle portion  2704  may also have a wall thickness from and including about 100 μm to and including about 3000 μm. Further in such implementations, each annulus  2707 A,  2707 B may have an outer diameter from and including 1 mm to and including 20 mm and a wall thickness from and including 100 μm to and including 5000 μm. The foregoing dimensions should be understood to be merely examples and designs in which the foregoing dimensions fall below or exceed the specified ranges should still be regarded as being within the scope of this disclosure. 
     Previous implementations discussed herein generally include balloons that are mounted coaxially with an overtube or similar medical tool and expand in a substantially uniform, radial direction about the tube. Nevertheless, it should be appreciated that in at least certain implementations, such balloons may instead be configured to expand directionally. For example,  28 A and  28 B illustrates a first example balloon  2800  eccentrically mounted to an overtube  2802 . Accordingly, as the balloon  2800  is inflated and expands (as illustrated in the transition from  FIG. 28A to 28B ), the balloon  2800  is biased to one side of the overtube  2802 . 
       FIGS. 29A and 29B  illustrate an alternative implementation in which a balloon  2900  is configured to expand directionally from an overtube  2902  or similar tool on which the balloon  2900  is mounted. Such directional expansion may be achieved, for example, by forming the balloon to have a localized region or side (indicated by hashed area  2904 ) having increased stiffness or rigidity as compared to other portions of the balloon  2900 . Such reinforcement may be achieved, for example, by increasing the wall thickness of the balloon  2900  in the region having reduced expansion; using a stiffer material in the region having reduced expansion; including internal or external ribs, bands, or similar reinforcing structures in the area having reduced expansion; or using any other suitable technique for locally increasing stiffness. 
     In addition to directional expansion, balloons in accordance with the present disclosure may have variable expansion along their length. For example  FIGS. 30A and 30B  are schematic illustrations of a balloon  3000  disposed on an overtube  3002  or similar tool. As illustrated in the transition between  FIGS. 30A and 30B , when inflated, a proximal portion of the balloon  3004  expands to a lesser extent than a distal portion of the balloon  3006 . Similar to the balloon  2900  of  FIGS. 29A and 29B , such variable expansion may be achieved by varying material, wall thickness, and reinforcement along the length of the balloon  3000 . 
     In addition to or as an alternative to selectively reinforcing sections of a balloon to provide variable expansion, balloons in accordance with the present disclosure may include distinct and selectively expandable compartments. For example,  FIG. 31  illustrates an example balloon  3100  disposed on an overtube  3102  or similar tool and defining three distinct and isolated internal compartments  3104 A- 3104 C. Each compartment  3104 A- 3104 C is connected to an independently controlled air line  3106 A- 3106 C such that air may be selectively supplied and removed from each of the compartments  3104 A- 3104 C to selectively control their respective expansion and deflation. 
       FIG. 32  illustrates an alternative approach to providing a balloon having variably expandable regions. More specifically,  FIG. 32  illustrates a sheath or outer balloon  3200  within which multiple and independently inflatable internal balloons  3204 A,  3204 B may be disposed. Each of the balloons  3200 ,  3204 A, and  3204 B may in turn be coupled to an overtube  3202  or similar tool. In such implementations, the outer balloon  3200  may include texturing or protrusions, as described herein, while the internal balloons may be substantially smooth. Similar to the compartmentalized balloon  3100  of  FIG. 31 , each internal balloon  3204 A,  3204 B may be in communication with a respective and independently controlled air line  3106 A,  3106 B to selectively control inflation and deflation of the internal balloons and, as a result, the overall shape of the outer balloon  3200 . 
     In certain implementations of the present disclosure, protrusions extending from the balloon may be reinforced to increase overall rigidity of the protrusions, thereby preventing or reduce bending or other deformation during transportation of the balloon within a physiological lumen or following anchoring of the balloon within the lumen. In certain implementations, such reinforcement of the protrusions may be provided on the internal surface of the balloon. For example,  FIGS. 33-35  each illustrate non-limiting examples of internal reinforcement that may be applied to the protrusions.  FIG. 33 , for example, illustrates a portion  3300  of an example inner balloon surface in which each protrusion (e.g., protrusion  3302 ) is individually reinforced by a corresponding bump (e.g., bump  3304  corresponding to protrusion  3302 ) or similar localized thickening of the balloon wall opposite the protrusion. As another example,  FIG. 34  illustrates a portion  3400  of another example inner balloon surface in which multiple protrusions (e.g., protrusions  3402 A- 3402 D) are linked by a corresponding ridge, rib, or similar reinforcing structure (e.g., rib  3404 ) extending along the inner surface of the balloon.  FIG. 35  illustrates another portion  3500  of an example inner balloon surface illustrating that such reinforcement may be non-uniform. For example, while protrusions  3502 A- 3502 C are reinforced using a common and straight rib  3504 , protrusions  3506 A- 3406 D are reinforced by a patch  3508  of balloon material. 
     Reinforcement of the protrusions may also be achieved by linking or connecting protrusions on the exterior surface of the balloon. For example,  FIG. 36  illustrates a portion  3600  of an external surface of a first example balloon in which adjacent protrusions (e.g., protrusions  3602 A,  3602 B) are linked or otherwise mutually reinforced by a rib  3604  extending therebetween.  FIG. 37  illustrates a portion  3700  of a second example balloon in which protrusions (e.g., protrusions  3702 A- 3702 D) are linked by continuous ribs (e.g., rib  3704 ). Finally,  FIG. 38  illustrates a portion  3800  of a third example balloon having non-uniform protrusion reinforcement. For example, protrusion  3802 A is coupled to and reinforced by each of its nearest neighboring protrusions, protrusions  3802 - 3802 D are reinforced to form an “L” shaped pattern, and protrusions  3802 E- 3802 H are reinforced by a patch  3804  or pad extending therebetween. 
     The foregoing examples of internal and external protrusion reinforcement are intended merely as non-limiting examples. More generally, reinforcement of protrusions in accordance with the present disclosure may be achieved by either or both of providing additional material on the inner surface of the balloon opposite the protrusions, providing additional material on the external surface of the balloon adjacent the protrusions, or forming a mechanical link between protrusions, such as by forming a rib or similar structure extending between protrusions. 
     The foregoing balloon designs are intended merely as examples and are not intended to limit the scope of the present disclosure. Rather, features of any balloon disclosed herein may be combined in any suitable manner. For example, any size, shape, and arrangement of protrusions may be implemented with any corresponding balloon shape or size. Similarly, other features, such as those related to controlled collapse, may be incorporated into any balloon design disclosure herein. Similarly, any specific dimensions or proportions provided in the context of specific balloon designs are intended merely as examples and should not be construed as limiting. More generally, any particular implementations of balloons discussed or illustrated herein should be regarded as one possible combination of features of balloons in accordance with the present disclosure. 
     Overtube Assemblies Including Balloon Inflation/Deflation Systems 
     An endoscopic overtube is a sleeve-like device designed to facilitate endoscopic procedures. During upper endoscopic procedures, for example, overtube may be used to protect, among other things, the hypopharynx from trauma during intubations, the airway from aspiration, and the esophagus during extraction of sharp foreign bodies. Similarly, during lower endoscopic procedures, such as enteroscopy and colonoscopy, overtubes may be used to protect various structures of the gastrointestinal tract while also preventing loop formation. 
     In endoscopic processes including endoscopic balloons, the balloon may be coupled to the overtube and the overtube may include passageways or ducts that extend along its length from the balloon to one or more proximal ports. For example, certain conventional balloon overtubes include a balloon and overtube with an inflation/deflation port and a fluid access port. Such conventional balloon overtubes are often operated using a separate and cumbersome inflation system coupled to the overtube by one or more small plastic tubes. The inflation system generally includes a pump and valves for providing air to and extracting air from the inflation/deflation port of the overtube via the plastic tubes. Such systems may be actuated by foot pedal or handheld button, either by the gastroenterologist user, or by a technician. 
     Among other issues, such conventional inflation systems are expensive to purchase and operate, time consuming to set up, and lack portability. Accordingly, such conventional systems generally preclude balloon endoscopy from being used in facilities that may lack the resources for a conventional system or in applications outside of an endoscopic center. 
     To address the foregoing issues, among others, an improved overtube assembly is provided. The improved overtube assembly includes an inflation/deflation system integrated with the overtube to provide a standalone or substantially standalone system. 
       FIG. 39  is a schematic illustration of an example overtube assembly  3900  in accordance with the present disclosure. As illustrated, the overtube assembly  3900  is disposed on an endoscope  10 . The overtube assembly  3900  includes an overtube  3902  coupled to a balloon  3904 . A balloon line  3906  extends along or through the overtube  3902  from the balloon  3904  to an inflation/deflation assembly  3908 . In certain implementations, the balloon line  3906  may be a lumen defined by the overtube  3902 ; however, in other implementations, the balloon line  3906  may be a separate lumen coupled to or embedded within the overtube  3902 . 
     The balloon  3904  may be, but is not necessarily limited to, an endoscopic balloon including one or more textured portions according to any implementation discussed herein. 
     The inflation/deflation assembly  3908  includes various ports and controls to facilitate the inflation and deflation of the balloon  3904 . For example, the inflation/deflation assembly  3908  includes each of an inflation port  3910  and a deflation port  3912 . The inflation port  3910  is adapted to be coupled to a suitable source of pressurized air (not shown), which may include, without limitation, “house air” available within an endoscopy or operation room suite, a hand pump, a hand syringe, a foot-actuated floor pump, or a reservoir of compressed air. Similarly, the deflation port  3912  may be configured to be coupled to a vacuum to facilitate rapid deflation of the balloon  3904 . Alternatively, the deflation port  3912  may vent to atmosphere. The overtube assembly  3900  may further include other ports, such as, but not limited to, a fluid in/out port  3913  to facilitate injection or removal of fluid from the physiological lumen within which the overtube assembly  3900  is disposed. 
     The inflation/deflation assembly  3908  further includes controls for selectively inflating and deflating the balloon  3904 . In the specific implementation illustrated in  FIG. 39 , for example, the inflation/deflation assembly  3908  includes each of an inflation button  3914  for selectively opening an inflation valve  3916  and a deflation button  3918  for selectively opening a deflation valve  3920 . When opened (e.g., by depressing the inflation button  3914 ), the inflation valve  3916  permits air flow from the air source through a regulator  3922  of the inflation/deflation assembly  3908  and to the balloon  3904  via the balloon line  3906 . Similarly, when opened, the deflation valve  3920  permits air flow from the balloon  3904 , through the balloon line  3906 , and out of the deflation port  3912 . 
     As noted, the inflation/deflation assembly  3908  may include a regulator  3922  disposed between the inflation port  3910  and the balloon line  3906 . In certain implementations, the regulator  3922  may be fixed to provide a predetermined flow rate at a predetermined pressure; however, in at least some implementations the regulator  3922  may be adjustable (e.g., by an adjustment knob  3924  or similar control element coupled to the regulator  3922 ). 
     The various control elements included in the inflation/deflation assembly  3908  may be mechanical, electronic, or a combination of both. In implementations in which electronic components are included, the inflation/deflation assembly  3908  may generally include suitable circuitry, memory, and processing components to perform various functions such as, but not limited to, receiving inputs from the buttons  3914 ,  3918 ; actuating the valves  3916 ,  3920 ; and adjusting the regulator  3922 . In certain implementations the inflation/deflation assembly  3908  may also be communicatively coupled to one or more remote computing devices that may be used to operator and/or collect data from the inflation/deflation assembly  3908 . To the extent any electronic components are included in the inflation/deflation assembly  3908 , the inflation/deflation assembly  3908  may further include an onboard power source (such as a battery) and/or may be electrically coupleable to an external power source, such as a wall socket or external battery. 
     In certain implementations, the inflation/deflation assembly  3908  may include an onboard pump between the inflation port  3910  and the regulator  3922  and the inflation port  3910  may simply be open to ambient air. In such implementations, the inflation/deflation assembly  3908  may further include one or more permanent or replaceable filter element disposed between the inflation port  3910  and the regulator  3922  to improve the quality of the air provided to the balloon  3904 . 
     As shown in  FIG. 39 , the inflation/deflation assembly  3908  may be directly coupled to a proximal portion of the overtube  3902 . In certain implementations, the inflation/deflation assembly  3908  may be specifically sized and shaped to be manipulated using one hand, thereby improving ease of use and freeing a user&#39;s second hand to perform other tasks. Accordingly, the size and shape of the inflation/deflation assembly  3908  may be chosen for any of right-, left-, or ambidextrous operation. 
     In at least certain implementations, the overtube assembly  3900 , including the inflation/deflation assembly  3908 , may be configured to be disposable in whole or in part. For example, in certain implementations, the overtube assembly  3900  may be disassembled in whole or in part, with certain of the components of the overtube assembly  3900  being recyclable or otherwise readily disposable. 
     It should be understood that the foregoing overtube assembly  3900  is merely an example and implementations of the present disclosure are limited to the specific implementation discussed above. Rather, overtube assemblies in accordance with the present disclosure more generally include an overtube to which flow and pressure regulating components are coupled and with which such flow and pressure regulating components are integrated into a unitary assembly. 
     Split Overtubes 
     Conventional overtubes, including balloon overtubes, are continuous tubular structures. As a result, such overtubes may only be installed on endoscopes (or similar tools) by inserting a distal end of the endoscope into a proximal end of the overtube and extending the endoscope through the overtube. This process necessarily requires that the endoscope be outside the patient and, as a result, must be performed at the outset of any endoscopic procedure. In certain instances, however, a physician may not know whether an overtube is required until mid-procedure. At such time in the procedure, it may be very difficult to fully intubate the patient due to irregular anatomy, or other complications. Physicians also sometime realize they cannot easily position the endoscope to successfully biopsy tissue. In these example cases, a physician would generally need to remove the endoscope from the patient, attach an overtube, re-intubate the patient, and deliver the endoscope to its prior location. This leads to increased procedure time and challenges of advancing the scope to the previous furthest point. Thus, there is a need to be able to attach an overtube mid-procedure and, more specifically, to attach an overtube to the endoscope and advance the overtube to the tip of the endoscope without losing any purchase with the endoscope, removing the endoscope from the patient, or otherwise backtracking in the procedure. 
     To address the foregoing issues, among others, a split or wraparound overtube is provided here. In general, the split overtube includes a longitudinally extending split that allows the overtube to be opened and placed onto an endoscope. To prevent separation of the split overtube and/or disengagement from the endoscope, the split overtube may include features to secure the overtube to the underlying endoscope. For example, in certain implementations, the overtube may have a high-friction inner surface adapted to frictionally engage the endoscope. Such high-friction properties may be a result of the material of the split overtube, a coating or adhesive applied to the inner surface, texturing of the inner surface, and the like. In certain implementations, friction between the overtube and the endoscope may be selectively modified by introducing a fluid into the annular space between the overtube and the endoscope, such that the fluid acts as a lubricant between the two components. 
     The overtube may also include features to prevent the overtube from splitting once coupled to the endoscope. For example, in certain implementations surfaces of the overtube that contact when closed about an endoscope may be textured or treated to frictionally engage each other. In certain implementations, the overtube may be configured to wrap about the endoscope such that portions of the overtube overlap. Like the previously mentioned contacting surfaces, the overlapping portions of the overtube may also include coatings, texturing, or structural features configured to engage each other and maintain the overtube in a closed configuration about the endoscope. 
     Referring first to  FIGS. 40A and 40B , an endoscope and overtube assembly  4000  is illustrated in each of a separated and coupled configuration. More specifically,  FIG. 40A  illustrates the endoscope  20  adjacent the overtube  4004 . The overtube  4004  includes a split  4006  extending along its length such that the overtube  4004  may be opened (e.g., into a “C”-shape) and an exposed/ex vivo portion of the endoscope  20  may be inserted laterally into the overtube  4004 . Although illustrated in  FIGS. 40A and 40B  as being straight, the split  4006  more generally extends along the full length of the overtube  4004 , but may extend both about and along the overtube  4004  in doing so. For example, instead of a straight split (such as illustrated), the split  4006  may be helical or include helically extending segments.  FIG. 40B  illustrates the endoscope and overtube assembly  4000  in an assembled configuration in which the endoscope  20  is disposed within the overtube  4004 . Once disposed on the endoscope  20 , the overtube  4004  may be advanced along the endoscope  20  (e.g., in vivo) to the tip of the endoscope  20 . 
     Although the overtube may be advanced along the endoscope  20 , in certain implementations, the frictional engagement between the endoscope  20  and the overtube  4004  may be designed to provide at least some resistance to undesirable movement of the endoscope  20  relative to the overtube  4004  once the overtube  4004  is installed.  FIGS. 41 and 42  provide two example approaches of modifying the engagement between the endoscope  20  and overtube  4004 . 
     Referring first to  FIG. 41 , a cross-sectional view of a first example overtube  4100  is provided. As illustrated, the overtube  4100  includes a split  4106  that allows the overtube  4100  to be opened for insertion of the endoscope. As illustrated in Detail A, at least a portion of the inner surface  4108  of the overtube  4100  may include a coating or layer  4110  with predetermined frictional properties. Similarly,  FIG. 42  is a cross-sectional view of a second example overtube  4200  is provided. As illustrated, the overtube  4200  also includes a split  4206  that allows the overtube  4200  to be opened for insertion of the endoscope. As illustrated in Detail B, at least a portion of the inner surface  4208  of the overtube  4200  may include texturing  4210  to modifying the frictional properties of the inner surface  4208 . Although various textures may be used, in at least certain implementations, such texturing  4210  may be similar to the texturing described above in the context of endoscopic balloons. It should be appreciated that similar coating or texturing may also be applied to portions of the exterior surface of the overtubes  4100 ,  4200  to modify the frictional engagement between the overtubes  4100 ,  4200  and any physiological lumen within which they may be used. 
       FIGS. 43-46  illustrate alternative configurations of split overtubes in accordance with the present disclosure and, in particular, different ways in which such overtubes may be retained on an endoscope. 
     Referring first to  FIG. 43 , a cross-sectional view of an overtube  4300  disposed on an endoscope  20  is provided. As illustrated, the overtube  4300  includes a lateral split  4304  including a first surface  4306 A and a second surface  4306 B. As illustrated, when disposed on the endoscope  20 , the first surface  4306 A and the second surface  4306 B abut. In certain implementations, the overtube  4300  may be formed from a material having sufficient rigidity that the first surface  4306 A and the second surface  4306 B are in positive contact. Alternatively or in addition, one or both of the first surface  4306 A and the second surface  4306 B may have a coating, layer, texture, adhesive, or similar treatment to increase frictional engagement between the first surface  4306 A and the second surface  4306 B. 
       FIG. 44  is a cross-sectional view of another overtube  4400  disposed on the endoscope  20 . As illustrated, the overtube  4400  includes a split  4404  formed between overlapping portions of the overtube  4400 . More specifically, when disposed about the endoscope  20  a first portion  4406 A of the overtube  4400  is disposed inwardly of a second portion  4406 B of the overtube  4400 , forming an interface between the inward surface of the first portion  4406 A and the outward surface of the second portion  4406 B. In certain implementations, the overtube  4400  may be formed from a material having sufficient rigidity that the first portion  4406 A of the overtube  4400  is maintained in positive contact with the second portion  4406 B of the overtube  4400 . Alternatively or in addition, one or both of the inward surface of the first portion  4406 A and the outer surface of the second portion  4406 B may have a coating, layer, texture, or similar treatment to increase frictional engagement at the interface between the two portions  4406 A,  4406 B. 
       FIG. 45  is a cross-sectional view of another overtube  4500  disposed on the endoscope  20 . As illustrated and similar to the overtube  4400  of  FIG. 44 , the overtube  4500  includes a split  4504  formed between overlapping portions of the overtube  4500 . More specifically, when disposed about the endoscope  20  a first portion  4506 A of the overtube  4500  is disposed inwardly of a second portion  4506 B of the overtube  4500 , forming an interface between the inward surface of the first portion  4506 A and the outward surface of the second portion  4506 B. In addition to the overlap at the interface, the first portion  4506 A and the second portion  4506 B may include mating or engaging structures. For example, as illustrated in  FIG. 45 , the first portion  4506 A includes a series of longitudinal ridges  4510  shaped to be received by corresponding longitudinal grooves  4512  defined in the second portion  4506 B. 
     As yet another example,  FIG. 46  is a cross-sectional view of an overtube assembly  4600  disposed on the endoscope  20 . As illustrated, the overtube assembly  4600  includes multiple overtubes and, more specifically an inner overtube  4601  and an outer overtube  4650 . Each of the inner overtube  4601  and the outer overtube  4650  may be similar to any of the other split overtube designs discussed herein; however, for purposes of the current example, each of the inner overtube  4601  and the outer overtube  4650  are similar to the overtube  4300  of  FIG. 43 . More specifically, the inner overtube  4601  includes a lateral split  4604  including a first surface  4606 A that abuts a second surface  4606 B. Similarly, the outer overtube  4650  includes a lateral split  4654  including a first surface  4656 A that abuts a second surface  4656 B, the lateral split  4654  enabling insertion of the inner overtube  4601  with the endoscope  20  therein to be received within the outer overtube  4650 . In certain implementations the inner overtube  4601  may be rotatable or otherwise movable within the outer overtube  4650 . 
     It should be appreciated that in at least some implementations, the outer overtube  4650  extend along only a portion of the inner overtube  4601 . In such implementations, multiple outer overtubes may also be distributed along the length of the inner overtube  4650 . In still other implementations the outer overtubes  4650  may instead be substituted with split rings, straps, clips, or similar components adapted to extend around and maintain the inner overtube  4601  in a closed configuration. 
     Further aspects of overtubes and overtube assemblies in accordance with the present disclosure are now provided with reference to  FIGS. 47-63 , which illustrate another example overtube assemblies and associated methods of manufacturing. 
       FIGS. 47-50  are an isometric view, a plan view, an elevation view, and a distal end view of the overtube assembly  4700 . As previously discussed, the overtube assembly  4700  may be disposed on an elongate/tubular medical tool. For purposes of the following discussion, the tubular medical device is generally referred to as an endoscope, however, it should be understood that the overtube assembly  4700  may be configured to work with other medical devices having generally tubular shapes, including medical devices other than endoscopes. 
     As illustrated in  FIG. 47 , the overtube assembly  4700  includes an overtube  4702  having a flexible tubular body  4704 . The tubular body  4704  generally includes a proximal end  4706  (indicated in  FIGS. 48 and 49 ) and a distal end  4708 . The tubular body  4704  defines a split  4710  extending from the proximal end  4706  to the distal end  4708 . As noted in the context of the foregoing example overtubes, the split  4710  permits the overtube assembly  4700  to receive an elongate medical tool, such as an endoscope, by inserting the tool through the split  4710  as opposed to passing the tool through a lumen defined by the tubular body  4704 . Notably, in at least some implementations, the split  4710  may include overlapping portions of the tubular body  4704  as previously discussed in the context of  FIGS. 43-46 . 
     The overtube assembly  4700  may further include one or more inflatable balloons, such as inflatable balloon  4712  and  4714 , which are illustrated as being disposed on opposite sides of the tubular body  4704  on a distal portion  4724  of the tubular body  4704 . Air may be provided to or removed from each of the inflatable balloons  4712 ,  4714  via respective air supply lumens  4716 ,  4718  defined by and extending through the tubular body  4704 . Although not illustrated, in at least certain implementations, each of the air supply lumens  4716 ,  4718  may extend fully through the tubular body  4704  and may be capped by an insert or otherwise sealed at the distal end  4708  of the tubular body  4704 . Also, while not illustrated, the proximal end of each air supply lumen  4716 ,  4718  may be coupled to one or more pumps or similar air supply devices that provide air to, remove air from, ventilate, etc. the inflatable balloons  4712 ,  4714 . Although described herein as an “air supply lumen”, similar lumens may be implemented that deliver any suitable fluid to or remove fluid from the inflatable balloons  4712 ,  4714 . 
     Although the overtube assembly  4700  includes inflatable balloons  4712 ,  4714 , in other implementations, the inflatable balloons  4712 ,  4714  may be omitted or replaced with other fluid-controlled features. In implementations in which the balloons are removed and not replaced with another device, the air supply lumens  4716 ,  4718  may be omitted. The inflatable balloons of other implementations discussed herein may similarly be omitted. 
     As most clearly shown in  FIG. 50 , in at least some implementations, the air supply lumens  4716 ,  4718  may be disposed on opposite sides of the split  4710  and may generally run parallel to the split  4710 . In other implementations, the air supply lumens  4716 ,  4718  may be defined within the tubular body  4704  at a location other than adjacent the split  4710 . Moreover, while the air supply lumens  4716 ,  4718  are shown as extending in a longitudinal direction, in other implementations, the air supply lumens  4716 ,  4718  may also extend in a circumferential direction as well. Also, while the split  4710  extends along the full length of the tubular body  4704 , the air supply lumens  4716 ,  4718  may only extend along a portion of the tubular body  4704  sufficient to extend from the proximal end  4706  of the overtube  4702  to the inflatable balloons  4712 ,  4714 . 
     Although illustrated in  FIGS. 47-49  as being a single tubular structure, in at least certain implementations, the tubular body  4704  may be embedded with or otherwise include additional structural elements and features. For example, the tubular body  4704  may include reinforcement in the form of ribs, ridges, or other similar structural elements disposed along the length of the tubular body  4704 . In certain implementations, such structural elements may be integrally formed with the tubular body  4704 . In other implementations, such structural elements may instead be separate components that are embedded within, attached to, or otherwise coupled to the tubular body  4704 . As another example, the tubular body  4704  may include one or more radiopaque markers to facilitate viewing of the overtube assembly  4700  using fluoroscopy. Similar to the reinforcing structures, in at least certain implementations such markers may be embedded within or attached to the tubular body  4704 . 
     As noted above, in the specific implementation illustrate in  FIGS. 47-49 , the overtube assembly  4700  includes two inflatable balloons  4712 ,  4714  that are disposed near the distal end of the overtube  4702  and on opposite sides of the overtube  4702 . As shown, the inflatable balloons  4712 ,  4714  include texturing in the form of frustoconical projections, similar to those of the balloon  2500  illustrated in  FIGS. 25A-25D  and discussed above. Although illustrated with frustoconical projections, it should be understood that the inflatable balloons  4712 ,  4714  may include any texturing disclosed herein on their exterior surfaces. It should also be appreciated that in at least some implementations, at least one of the inflatable balloons  4712 ,  4714  may be untextured. 
     This specific arrangement is provided merely as an example and other configurations are contemplated. For example, in certain implementations the overtube assembly  4700  may include any suitable number of inflatable balloons, including one. Also, the one or more inflatable balloons may be disposed at any location along the overtube  4702 . To the extent the overtube assembly  4700  includes multiple inflatable balloons, such balloons may be disposed at different longitudinal locations along the overtube  4702 . Similarly, while the inflatable balloons  4712 ,  4714  collectively extend around substantially the full circumference of the overtube assembly  4700 , in other implementations, the inflatable balloons may instead be disposed only on one side of the overtube  4702  or otherwise extend around only a portion of the circumference of the overtube  4702 . 
       FIG. 51  is a partial longitudinal cross-section of the overtube assembly  4700 . As illustrated, the tubular body  4704  of the overtube  4702  defines a tubular cavity  4726  within which the endoscope  20  or other medical tool is received via the split  4710  (shown in  FIG. 49 ).  FIG. 51  further illustrates the air supply lumen  4716 , which is defined by and extends along the tubular body  4704 . Each air supply lumen defined by the tubular body  4704  is in communication with an internal volume of one or more of the inflatable balloons  4712 ,  4714  (texturing of the balloons is omitted in  FIG. 51  for clarity). In the specific example of the overtube assembly  4700 , for instance, the air supply lumen  4716  is in communication with an internal volume  4713  of the inflatable balloon  4712 . More specifically, the tubular body  4704  defines an overtube port  4717  in communication with the air supply lumen  4716 . The inflatable balloon  4712  similarly defines a balloon port  4728  in communication with the internal volume  4713 . During assembly and as illustrated in Detail C of  FIG. 51 , the inflatable balloon  4712  is coupled to the tubular body  4704  such that the overtube port  4717  and the balloon port  4728  are also in communication, thereby enabling air flow between the internal volume  4713  of the balloon  4712  and the air supply lumen  4716  during use of the overtube assembly  4700 . 
     In certain implementations, each of the overtube port  4717  and the balloon port  4728  may be formed after initial extruding, molding, etc. of the tubular body  4704  and the balloon  4712 . For example, following extrusion of the tubular body  4704 , the overtube port  4717  may be formed by cutting, puncturing, etc. a wall  4730  of the tubular body  4704 . Similarly, following forming of the balloon  4712 , a wall  4732  of the balloon  4712  may be cut, punctured, etc. to form the balloon port  4728 . Alternatively, in either case, either of the overtube port  4717  or the balloon port  4728  may be formed directly during the extrusion, molding, etc. process. 
     In certain implementations, a hollow conduit  4734  or similar reinforcing structure may also extend between the overtube port  4717  and the balloon port  4728  and provide an air channel between the internal volume  4713  of the inflatable balloon  4712  and the air supply lumen  4716 . The hollow conduit  4734  may be inserted after formation of the overtube port  4717  and the balloon port  4728 . In other implementations and as illustrated in Detail C′, the conduit  4734  may alternatively be used to puncture each of the wall  4730  of the tubular body  4704  and the wall  4732  of the balloon  4712  to form each of overtube port  4717  and the balloon port  4728 . 
       FIG. 52  is a detailed view of the distal end  4708  of the overtube assembly  4700 . Among other things,  FIG. 52  illustrates the inclusion of a notch  4750  formed in the distal end of the tubular body  4704 , which may be included in implementations of the present disclosure. As illustrated, the notch  4750  generally extends proximally from a distal end  4752  of the tubular body  4704 , tapering toward the split  4710 , and ultimately being in communication with the split  4710   
     The notch  4750  is provided to facilitate placement of the overtube assembly  4700  onto an elongate medical tool, such as an endoscope. More specifically, when disposing the overtube assembly  4700  onto the elongate medical tool, the elongate medical tool is first placed within the notch  4750 . As the overtube  4702  is forced onto the tool, the notch  4750  provides a wedge-like action that opens the overtube  4702  along the split  4710 , thereby facilitating placement of the overtube assembly  4700  onto the tool. Inclusion of the notch  4750  is particularly useful in implementations in which the overtube  4702  is particularly thick or stiff and, as a result, separation along the split  4710  may be difficult without the added leverage afforded by the notch  4750 . Although the notch  4750  is shown as being triangular in  FIG. 52 , in other implementations, the notch  4750  may have other shapes. However, in general, the notch  4750  begins at the distal end  4752  of the overtube  4702  and tapers proximally. 
       FIGS. 53 and 54  are an isometric view and an end view, respectively, of the inflatable balloon  4712  of the overtube assembly  4700 . More specifically,  FIGS. 53 and 54  illustrated the inflatable balloon  4712  in an unstrained state. Similar to the previously disclosed balloons, the balloon  4712  includes an elongate body  5302  including a middle portion  5304  and tapering end portions  5306 A,  5306 B. In contrast to the balloons previously disclosed herein, which had a substantially cylindrical shape through which an overtube or medical tool may extend, the inflatable balloon  4712  has a semi-annular shape intended to be disposed on the exterior of the overtube  4702  of the overtube assembly  4700 . Accordingly, the inflatable balloon  4712  includes an inner concave surface  5308  shaped to receive the overtube  4702 . In certain implementations, the balloon  4712  is formed to have the inner concave surface  5308  in others however, the balloon  4712  may have an oblong or “D”-shaped cross-section and the concave surface  5308  may be formed by indenting the inner surface of the balloon prior to application onto the overtube  4702 . 
     The inflatable balloon  4712  may further include a textured outer convex surface  5310 . As illustrated, the texturing  5312  on the outer convex surface  5310  includes longitudinally extending rows of frustoconical protrusions; however, texturing of the outer convex surface  5310  may generally conform to any texturing discussed herein. 
     To facilitate assembly, the inflatable balloon  4712  may be formed with one or more open ends, such as open end  5314 . During assembly, the open end  5314  permits access to the internal volume of the balloon  4712  to facilitate coupling of the balloon  4712  to the overtube  4702 . For example, the balloon  4712  may be positioned onto the overtube  4702  and then each of the balloon  4712  and the overtube  4702  may be simultaneously pierced from within the balloon  4712  to form the overtube port  4717  and the balloon port  4728  previously discussed in the context of  FIG. 51 . Similarly, the open end  5314  of the balloon  4712  may be used to enable insertion of a conduit  4734 , as illustrated in Detail C′ of  FIG. 51 . As illustrated in the transition between  FIGS. 55 and 56  (each of which is an isometric view of the overtube assembly  4700 , the open end  5314  is ultimately closed (e.g., using an adhesive, plastic welding, or similar process), thereby sealing the inflatable balloon  4712 . 
     In certain implementations of the present disclosure, the tubular body of the overtube may include cutouts or similar voids to increase the flexibility of the overtube. In certain implementations, such voids may be evenly distributed along and about the length of the overtube to provide relatively uniform increased flexibility along the length of the tubular body. Alternatively, such voids may be disposed at specific locations (e.g., at particular longitudinal locations and/or on a particular side of the tubular body) to locally vary the flexibility of the tubular body. In certain implementations, localized thinning, scoring, grooves, etc. may similarly be used to vary the flexibility of the tubular body along its length. 
     In implementations in which voids or similar flexibility modifying features are disposed along the length of the tubular body, the tubular body may be wrapped, at least in part, in a low-friction sheath. For example, subsequent to coupling the tubular assembly to an endoscope or similar elongate tool, tape, a wrap, or similar layer formed of a low friction material (e.g., silicone) may be applied to the overtube of the overtube assembly to reduce interaction between the tubular body (and, in particular, any edges of the voids or flexibility modifying features) and the physiological lumen within which the tool is being used. 
     For example,  FIGS. 57 and 58  are an isometric view and a distal end view, respectively, of an alternative overtube assembly  5700  in accordance with the present disclosure and which includes flexibility modifying features as discussed above. More specifically,  FIG. 57  illustrates a distal portion of the overtube assembly  5700 . The overtube assembly  5700  includes an overtube  5702  having a flexible tubular body  5704  that extends from a proximal end (not shown) of the overtube  5702  to a distal end  5708  of the overtube  5702 . Similar to the tubular body  4704  of the overtube assembly  4700 , the tubular body  5704  defines a split  4710  extending from its proximal end to the distal end  4708  to facilitate coupling of the overtube assembly  5700  to an endoscope or similar elongate tool. The overtube assembly  5700  further includes one or more inflatable balloons, such as inflatable balloon  5712  and  5714 , which are illustrated as being disposed on opposite sides of the tubular body  5704  on a distal portion  5724  of the tubular body  5704 . 
     As illustrated in  FIG. 57 , the tubular body  5704  of the overtube assembly  5700  includes a solid/continuous portion, referred to herein as a strip or backbone  5740 , from which multiple ribs or bands (e.g., bands  5742 A,  5742 B and bands  5744 A,  5744 B) extend. As a result, voids or gaps (e.g., gap  5746  between band  5742 A and  5744 A) are formed between adjacent bands. As a result of the gaps, the overall flexibility of the tubular body  5704  is significantly increased as compared to the flexibility of a substantially continuous tubular body, such as the tubular body  4704  of the overtube assembly  4700  of  FIG. 47 . 
     In certain implementations, the tubular body  5704  may further include a pair of flexible rods  5746 A,  5746 B to which the bands are coupled and that extend along opposite sides of the split  5710 . For example, each of bands  5742 A and  5744 A are coupled to rod  5746 A while each of bands  5742 B and  5744 B are coupled to rod  5746 B. Among other things, the rods  5746 A,  5746 B provide additional structural stability for the tubular body  5704 . 
     While illustrated in  FIG. 57  as being paired along the length of the tubular body  5704 , implementations of the present disclosure may include bands that are offset relative to each other. 
     Air may be provided to or removed from each of the inflatable balloons  5712 ,  5714  via respective air supply lumens  5716 ,  5718  extending along the tubular body  5704 . As shown in  FIG. 57 , the air supply lumens  5716 ,  5718  of the example overtube assembly  5700  extend inwardly from the backbone  5740 , opposite the split  5710 . In certain implementations, the air supply lumens  5716 ,  5718  may be integrally formed with the backbone  5740 . Alternatively, the air supply lumens  5716 ,  5718  may be separately formed tubules that are coupled to the backbone  5740  using any suitable method. As yet another alternative, the air supply lumens  5716 ,  5718  may be defined by and extend through the rods  5746 A,  5746 B. 
     Other than their placement opposite the split  5710 , the air supply lumens  5716 ,  5718  are structurally and functionally similar to those included in the overtube assembly  4700  discussed above. More specifically, during assembly, the air supply lumens  5716 ,  5718  are made to be in communication with internal volumes of the inflatable balloons  5712 ,  5714  (e.g., by using ports defined in the tubular body and balloons and/or suitable conduits extending between the internal volume of the balloons and the air supply lumens). A proximal end (not shown) of the air supply lumens  5716 ,  5718  is also configured to be coupled to a pump or other air supply device (not shown) to supply air to and/or remove air from the internal volumes of the inflatable balloons  5712 ,  5714  via the air supply lumens  5716 ,  5718 . In certain implementations, the air supply lumens  5716 ,  5718  may extend along the full length of the tubular body  5704 . In such implementations, the distal ends of the air supply lumens  5716 ,  5718  may also be capped, plugged, or otherwise sealed (e.g., using plugs  5748 A,  5748 B, shown in  FIG. 58 ). 
     In alternative implementations of the backbone-style overtube, the rods  5746 A,  5746 B may be omitted and the tubular body  5704  may be configured similar to a comb-style binding spine. For example, the bands may extend from the backbone  5740 , extend circumferentially about the tubular body  5704 , and come into contact with either the internal or external surface of the backbone  5740 . In such implementations, the bands may extend from only one side of the backbone  5740  or may extend from both sides of the backbone  5740  in an interdigitated manner. In at least some implementations, the bands may be configured to extend circumferentially past the backbone. 
       FIG. 59  is a partial isometric view of yet another overtube assembly  5900  in accordance with the present disclosure.  FIG. 60  is a more detailed isometric view of a distal end of the overtube assembly  5900 . The overtube assembly  5900  includes an overtube  5902  having a flexible tubular body  5904  that extends from a proximal end (not shown) of the overtube  5902  to a distal end  5908  of the overtube  5902 . Similar to the tubular bodies of previously discussed implementations, the tubular body  5904  defines a split  5910  extending from its proximal end to the distal end  5908  to facilitate coupling of the overtube assembly  5900  to an endoscope or similar elongate tool. The split  5910  is shown in a closed configuration using a zipper-style closure  5950 , which is discussed below in further detail. The overtube assembly  5900  further includes one or more inflatable balloons, such as inflatable balloon  5912  and  5914 , which are illustrated as being disposed on opposite sides of the tubular body  5904  on a distal portion  5924  of the tubular body  5904 . 
     Similar to the tubular body  5704  of the overtube assembly  5700 , the tubular body  5904  includes features configured to modify the flexibility of the tubular body  5904  as compared to a substantially solid tubular body. In particular, the tubular body  5904  defines a plurality of voids or holes (e.g., void  5942 ) distributed along its length and around its circumference. Similar to the gaps between the bands of the tubular body  5704  illustrated in  FIG. 57 , the voids or holes of the tubular body  5904  similarly reduce the rigidity of the tubular body  5904 . 
     Although illustrated in  FIGS. 59 and 60  as being uniformly distributed along the tubular body  5904 , such holes may instead be concentrated at particular locations to locally modify the flexibility of the tubular body  5704 . Moreover, implementations of the present disclosure are not limited to holes or voids or any particular shape or size. 
     Air may be provided to or removed from each of the inflatable balloons  5912 ,  5914  via respective air supply lumens  5916 ,  5918 . Similar to the air supply lumens  5716 ,  5718  of the overtube assembly  5700 , the air supply lumens  5916 ,  5918  of the overtube assembly  5900  extend inwardly from a side of the tubular body  5904  opposite the split  5910 , however, they may be disposed or otherwise routed in any suitable manner along the tubular body  5904  provided they enable air to be supplied/removed from the inflatable balloons  5912 ,  5914 . 
     As noted above, the overtube assembly  5900  includes a closure mechanism and, in particular, a zipper-style closure  5950  to facilitate closing the split  5910 . Although not necessary in all implementations of the present disclosure, closure mechanisms, such as the zipper-style closure  5950 , can provide additional reinforcement and retention of the overtube assembly on the endoscope or other elongate tool in addition to any biasing of the tubular body into a closed shape resulting from its shape and material. 
     Mechanical closures in accordance with the present disclosure may include closures that are integrated into the tubular body and extend along at least a portion of the split. The zipper-style closure  5950 , for example, is coupled to or otherwise integrated with the tubular body  5904  and extends along a substantial portion of the split  5910 . Another example of an integrated closure is provided in  FIG. 45 . As discussed above, the overtube  4500  illustrated in  FIG. 45  overlapping portions  4506 A,  4506 B that form an interface. The overlapping portions of the overtube further include corresponding ridges  4510  and grooves  4512  shaped to positively engage each other when the overtube  4500  is disposed on an endoscope or similar tool. 
     In other implementations, the tubular body of the overtube assembly may include interlocking tabs, snaps, clasps, or other similar closure mechanisms disposed along the length of the split. 
     Alternatively, closures may be separate components that are disposed along the tubular body and that provide retentive force onto the tubular body. For example, one or more of clips, bands, split rings, or similar elements may be disposed along the length of the tubular body after insertion of an elongate tool into the tubular body to provide additional retention of the tubular body onto the tool. 
     In certain implementations, the closures mechanisms may require additional tools or components to facilitate their use. For example,  FIG. 61  illustrates a pull tab tool  5960  that may be used to open and close the zipper-style closure  5950  of the overtube assembly  5900 . Similar to a conventional zipper, when the zipper-style closure  5950  is open/disengaged, distal ends of each half  5952 A,  5952 B of the zipper-style closure  5950  may be inserted into a proximal end of the pull tab tool  5960 . The pull tab tool  5960  may then be translated proximally along the zipper-style closure  5950 , engaging the interdigitating teeth of the closure halves  5952 A,  5952 B. In at least some implementations, the zipper-style closure  5950  may be configured such that the pull tab tool  5960  may be disengaged after closing the zipper-style closure  5950 . For example, the pull tab tool  5960  may be disengaged by continuing to slide the pull tab tool  5960  beyond a proximal extent of the zipper-style closure  5950 . It should also be noted that in alternative implementations, the zipper-style closure  5950  may be configured such that to close the zipper-style closure  5950 , proximal ends of the halves  5952 A,  5952 B may be inserted into a distal end of the pull tab tool  5960  and the pull tab tool  5960  may be translated distally. 
       FIG. 62  is a cross-sectional view of another overtube  6200  and corresponding closure tool  6250 . As illustrated, the overtube  6200  is disposed on an endoscope  20 . As illustrated and similar to the overtubes  4400  of  FIG. 44 and 4500  of  FIG. 45 , the overtube  6200  includes a split  6204  formed between overlapping portions of the overtube  6200 . More specifically, when disposed about the endoscope  20  a first portion  6206 A of the overtube  6200  is disposed inwardly of a second portion  6206 B of the overtube  6200 , forming an interface between the inward surface of the first portion  6206 A and the outward surface of the second portion  6206 B. In addition to the overlap at the interface, the first portion  6206 A and the second portion  6206 B may include mating or engaging structures. In particular, the first portion  6206 A includes a T-shaped ridge  6210  shaped to be received by a corresponding T-shaped groove  6212  defined in the second portion  6206 B. 
     In certain implementations, engagement of mating structures, such as those illustrated in  FIGS. 45 and 62  may be facilitated by a tool that may be disposed on, applied to, or moved along the overtube. Such tools may be particularly beneficial in implementation in which closing the split by engaging the mating structures strictly may be For example, the tool  6250  illustrated in  FIG. 62  is substantially rigid and shaped to be fit over and slid longitudinally along the length of the overtube. As the tool is slid along the overtube, it forces the ridge  6210  into the groove  6212 , thereby closing the split  6204  of the overtube. More generally, however, the tool  6250  may be any device suitable to apply pressure onto the overtube  6200  to engage the mating structures of the overtube. 
       FIG. 63  is a method  6300  for manufacturing an overtube assembly, such as the overtube assembly  4700  of  FIGS. 50-53 . For explanatory purposes only, reference is made to the overtube assembly  4700  and its components. However, implementations of the method  6300  are not limited to the overtube assembly  4700  as illustrated in  FIGS. 50-53 . 
     In general, the method of manufacturing includes forming each of the tubular body  4704  of the overtube  4702  and each of the inflatable balloons  4712 ,  4714 . Forming the tubular body  4704  generally includes forming the split  4710  extending along the tubular body  4704 . The inflatable balloons  4712 ,  4714  are then coupled to the tubular body  4704  such that the internal volumes of the inflatable balloons  4712 ,  4714  are in communication with the air supply lumens  4716 ,  4718  of the overtube  4702 . Accordingly, in certain implementations, manufacturing the overtube assembly  4700  may further include forming ports in the balloons  4712 ,  4714  and/or the tubular body  4704  and disposing the inflatable balloons  4712 ,  4714  onto the tubular body  4704  such that each of the ports of the tubular body  4704  are in communication with a respective port of an inflatable balloon  4712 ,  4714 . 
     In light of the foregoing, operation  6302  includes forming the tubular body  4704 . Although any suitable process may be used to form the tubular body  4704 , in at least one implementation of the present disclosure, the tubular body  4704  is formed using an extrusion process. In such implementations, the tubular body  4704  may be formed using an extrusion machine having a die shaped to form each of the tubular cavity  4726  and the air supply lumens  4716 ,  4718  of the tubular body  4704 . 
     In at least certain implementations, the tubular body  4704  is formed from at least one of Nylon, PFA, PET, PTFE, FEP, HDPE, and TPPE. The material of the tubular body  4704  may also include additives to reduce surface friction of the tubular body  4704 . For example, in one specific implementation, the tubular body may be formed from Hytrel Thermoplastic Polyester Elastomer with Everglide. In certain implementations, the tubular body  4704  may have a wall thickness from and including about 0.25 mm to and including about 1.0 mm. Although not limited to such implementations, thinner walled tubular bodies according to the present disclosure may generally be formed from a more rigid polymer than thicker-walled tubular bodies such that the thin-walled tubular bodies have sufficient rigidity to advance within the physiological lumen of the patient (e.g., the GI tract). In one specific implementation, the wall thickness of the tubular body  4704  may be about 0.75 mm. Although not limited to specific dimensions, in at least certain implementations, the air supply lumens  4716 ,  4718  may have a diameter of approximately 0.8 mm and a wall thickness of approximately 0.33 mm. In general, however, this air supply lumen diameter and wall may be made as small and thin as possible in order to minimize the size of the tubular body and, as a result, minimize the volume invaded within the physiological lumen. Similarly, other features of the tubular body may be formed to be as thin and small as possible as thinner and smaller features generally result in the tubular body being more flexible and better able to move through any turns of the physiological lumen within which it is deployed. Nevertheless, for certain materials (e.g., silastic polymers), minimum wall thickness and other dimensions may be limited by manufacturing. Also, if the lumen is intended to deliver/remove fluids other than air, the lumen diameter may need to be larger compared to air to account for the increased viscosity of the fluid. 
     Formation of the tubular body may include surface treating a portion of either the interior or exterior surface of the tubular body  4704  to provide increased friction. For example and as discussed in the context of  FIGS. 41 and 42 , the internal surface of overtubes in accordance with the present disclosure may be coated or have integrally formed texturing at selective locations to increase friction with the medical tool disposed within the overtube. Similarly, and as discussed below in the context of  FIGS. 59-66 , the exterior surface of devices in accordance with the present disclosure, including the overtube  4702  of the overtube assembly  4700 , may similarly have exterior surfaces adapted to increase friction with the interior wall of a physiological lumen. For example, such exterior surfaces may be coated or include integrally formed texturing similar to the interior surfaces previously noted. 
     In operation  6304 , the split  4710  of the tubular body  4704  is formed. In at least certain implementations, formation of the split  4710  occurs during the extrusion process, e.g., by using an extrusion die where the wall of the tubular body  4704  is not continuous. Accordingly, the process of forming the tubular body  4704  (e.g., operation  6302 ) and forming the split  4710  along the tubular body  4704  (e.g., operation  6304 ) may occur simultaneously. 
     Alternatively, the wall  4730  of the tubular body  4704  may be extruded or otherwise formed to have a continuous circumference. In such cases, an additional cutting/splitting process may be required. In certain cases, splitting of the tubular body  4704  may be achieved using a knife or similar cutting tool disposed adjacent the extrusion machine such that the tubular body  4704  is split as it is extruded. Alternatively, a knife or similar cutting implement may be used to split the tubular body  4704  after the tubular body  4704  has been fully extruded. In at least certain implementations, the tubular body  4704  may be formed in operation  6302  with a seam or similar thin-walled portion to guide splitting. In such implementations, the seam may be designed such that splitting of the tubular body  4704  may be achieved by hand, e.g., by pulling apart the tubular body  4704  at the seam. 
     In operation  6306 , a notch  4750  is formed in the distal end  4708  of the tubular body  4704 . As previously discussed in the context of  FIG. 52 , a notch  4750  may be formed in the distal end  4708  of the tubular body  4704  to facilitate insertion of an endoscope  20  or similar elongate medical tube into the overtube  4702 . More specifically, when disposing the overtube assembly  4700  on an endoscope  20 , the endoscope  20  is first inserted into the distal extent of the notch  4750 . Formation of the notch  4750  may include, among other things, trimming or otherwise cutting away the tubular body  4704  either by hand or using an automated machine. 
     Operations  6302 - 6306  generally correspond to manufacturing and forming of the tubular body  4704 . As discussed above, other implementations of the present disclosure may include additional features and structures not included in the overtube assembly  4700 . To the extent such features are not specifically included in the method  6300 , formation of such features are nevertheless contemplated to be included in manufacturing methods according to the present disclosure. For example and among other things, manufacturing methods according to the present disclosure may include operations directed to modifying the flexibility of the tubular body. For example and referring to the overtube assembly  5700  of  FIG. 57 , manufacturing methods according to the present disclosure may include may include forming the bands (e.g., bands  5742 A,  5742 B and bands  5744 A,  5744 B) (and, as result the gaps/voids between the bands) and coupling the bands to the rods  5746 A,  5746 B. As another example and referring to the overtube assembly  5900  of  FIG. 59 , forming the tubular body may include forming the voids (e.g. void  5942 ). Manufacturing methods according to the present disclosure may also include the formation or inclusion of additional features to the tubular body. For example and again referring to the overtube assembly  5900  of  FIG. 59 , manufacturing methods of the present disclosure may include adding a closure mechanism, such as the zipper-style closure  5950 , to the tubular body. 
     In operation  6308 , the balloons  4712 ,  4714  are formed. Non-limiting examples of balloon manufacturing methods are discussed above in the context of  FIGS. 8 and 9 . In general, however, forming the balloons  4712 ,  4714  generally includes molding or otherwise producing an initial shape of the balloons  4712 ,  4714 . In certain implementations, the balloons  4712 ,  4714  may have integrally formed texturing, however, in other cases, texturing may be applied to the balloons  4712 ,  4714  after an initial molding process. To the extent the balloons  4712 ,  4714  are not produced having a shape that conforms to the overtube  4702 , forming the balloons  4712 ,  4714  may further include manipulating or shaping the balloons  4712 ,  4714  to conform to the overtube  4702 . 
     In operation  6310  ports are formed in the tubular body  4704 . As described above, the overtube ports (e.g., overtube port  4717 , illustrated in  FIG. 51 ), are in communication with a respective one of the air supply lumens  4716 ,  4718 . Forming each air overtube port generally includes forming a passage through the wall  4730  of the tubular body  4704  such that the passage extends from an exterior surface of the tubular body  4704  and terminates at one of the air supply lumens  4716 ,  4718 . Accordingly, forming the overtube ports may include, among other things, cutting, puncturing, or similarly altering the tubular body  4704 . 
     In operation  6312 , balloon ports are formed in the inflatable balloons  4712 ,  4714 . As previously discussed, each inflatable balloon generally includes a balloon port that enables air to be passed into or removed from an internal volume of the inflatable balloon, thereby inflating or deflating the balloon. Similar to the overtube ports, a balloon port for each inflatable balloon may be formed by cutting, puncturing or similarly altering the wall of the inflatable balloon. 
     In operation  6314  the inflatable balloons  4712 ,  4714  are coupled to tubular body  4704 . Coupling of the inflatable balloons  4712 ,  4714  to the tubular body  4704  generally includes disposing the inflatable balloons  4712 ,  4714  onto the tubular body  4704  such each of the balloon ports of the inflatable balloons  4712 ,  4714  is in communication with one of the overtube ports of the tubular body  4704 . The inflatable balloons  4712 ,  4714  may then be attached to the tubular body  4704 , such as by using an adhesive, fusing the inflatable balloons  4712 ,  4714  to the tubular body  4704 , or by any other suitable process. 
     In operation  6316 , a tubular conduit  4734  is inserted through each pair of balloon ports and overtube ports to reinforce the pathway between the ports. In other implementations, the tubular conduit  4734  may be omitted. 
     In certain implementations, the inflatable balloons  4712 ,  4714  may be coupled to the tubular body  4704  prior to formation of either of the balloon ports or overtube ports. For example, in certain implementations, the balloons  4712 ,  4714  may be coupled to the tubular body  4704  and the balloon and overtube ports may then be formed in a substantially simultaneous manner by cutting, puncturing, etc. the tubular body  4704  and the balloons  4712 ,  4714  after coupling. In other implementations, the step of inserting the tubular conduit  4734  may also occur 
     In operation  6318  and if the air supply lumen extends along the full length of the overtube  4702 , the distal end of the air supply lumens  4716 ,  4718  may be sealed. For example, caps or similar inserts may be disposed in the distal end of the air supply lumens. In other implementations, a filler or adhesive may be injected into the distal ends of the air supply lumens. Similarly and as illustrated in  FIGS. 55-56 , the balloons  4712 ,  4714  may be sealed (operation  6320 ). 
     The forgoing example implementations are intended merely to illustrate various concepts of split overtubes in accordance with the present disclosure and should be regarded as non-limiting. 
     Expandable Overtubes 
     In certain use cases and with certain patients, only relatively small endoscopes may be advanced through a given physiological lumen. In other words, a gastroenterologist or similar physician or technician may be prevented from inserting larger diameter scopes and advancing such scopes as far as needed to perform a procedure. One specific example is with patients with altered anatomy resulting from bariatric or other similar procedures. 
     In other cases, a side-facing endoscope may ultimately be needed for the procedure, but advancing a larger, side-facing scope may be challenging due to the patient&#39;s anatomy, among other things. In such cases, the ability to use a forward facing endoscope to reach the desired location is valuable only if an overtube can then be placed so that the overtube may be used to guide a larger scope (e.g., a side facing scope) to the desired location. 
     To address the foregoing issues, among others, the current disclosure includes an expandable overtube. In a first configuration, such as may be used during insertion of first, smaller endoscope (or similar tool) the expandable overtube is compressed to a first, smaller diameter. Upon removal of the first endoscope, a second, larger endoscope (or similar tool) may be inserted into the overtube which expands to accommodate the larger tool. In certain implementations, for example, in the first configuration the overtube may have an inner diameter of approximately 10 mm but may be configured to expand to 15 mm or more in response to insertion of a larger tool. To facilitate the forgoing expansion and contraction, the overtube may include an embedded mesh that provides structural rigidity to the overtube in each of the compressed and expanded configurations. 
       FIGS. 64A-64C  illustrate an example procedure using an expandable overtube in accordance with the present disclosure. Referring first to  FIG. 64A , a physiological lumen  30  is shown within which an endoscope assembly  6400  is disposed, the endoscope assembly  6400  including a first endoscope  6402  disposed within an expandable overtube  6404 . 
     The first endoscope  6402  may have a first diameter for use in intubating the patient with the expandable overtube  6404 . Once intubated, the first endoscope  6402  may be removed and a second endoscope or tool  6406  may be inserted into the overtube  6404 , as illustrated in  FIG. 64B . As the second endoscope or tool  6406  is advanced through the overtube  6404 , an outward force is applied to the overtube  6404  causing it to expand. In certain implementations, such expansion may be facilitate, in part, by an embedded mesh within the overtube  6404  configured to retain its shape when expanded outwardly. 
     As shown in  FIG. 64C , the second endoscope or tool  6406  may be advanced to extend beyond the now-expanded overtube  6404  to the original position of the first endoscope  6402  illustrated in  FIG. 64A . 
     Any surface of the overtube  6404  may include texturing in accordance with the present disclosure. For example and without limitation, the outer surface of the overtube  6404  may include texturing configured to facilitate frictional engagement of the overtube  6404  with the inner surface of the physiological lumen within which the overtube  6404  is disposed. Such frictional engagement may prevent slippage or shifting of the overtube  6404  during expansion of the overtube  6404  in response to insertion of the second, larger tool  6406  into the overtube  6404 . In implementations in which the overtube  6404  is textured, such texturing may be applied to substantially the entire length of the overtube  6404  or may be applied to one or more segments of the overtube  6404 . In certain implementations, the texturing may be configured to have a first engagement level when the overtube  6404  is in a first (e.g., the compressed) configuration, but to have a second engagement level when the overtube is in a second (e.g., the expanded) configuration, the second engagement level resulting from a difference in strain applied to the textured portions of the overtube  6404 . 
     The forgoing example implementations are intended merely to illustrate various concepts and applications of an expandable overtube in accordance with the present disclosure and should be regarded as non-limiting. 
     Textured Endoscopic Tools 
     Endoscopic procedures may include a biopsy or similar removal of a portion of tissue. When a snare or a biopsy catheter is used, the location of the scope and the tissue of interest may be located such that holding the snare steady relative to the tissue and the scope may be extremely challenging, particularly because the snare/biopsy catheter is generally unsupported within the physiological lumen within which the biopsy is to be taken. 
     To address the foregoing issues, among others, textured endoscopic tools are provided herein. In one implementation, texturing is applied to a snare, biopsy forceps, or other endoscope gastroenterology tools. Such texturing may be used to frictionally engage or adhere the tool to an inner wall of a physiological lumen and to help steady the tool relative to the tissue being removed. In certain implementations, texturing is disposed on the snare, biopsy tool, etc., itself. Alternatively or in addition to texturing of the tool itself, texturing may also be applied to a catheter through which the tool is delivered. In the latter case, the catheter adheres to the wall of the physiological lumen and is steadied by such adherence. 
     Texturing on the tool and/or catheter may also be used to pull tissue (e.g., a polyp or the wall of the physiological lumen) to facilitate tissue removal or to improve a physician&#39;s view of the physiological lumen. Notably, such tissue manipulation relies on relatively minimal engagement with the tissue, particularly when compared to conventional approaches in which a snare or similar tool is used to grasp the tissue. 
       FIG. 65  is a schematic illustration of an operational environment  6500  including a physiological lumen  6501  in which an endoscopic tool  6502  is disposed. For purposes of the current example, the physiological lumen  6501  is assumed to include a polyp  6503  which is to be removed; however, it should be appreciated that implementations of the current disclosure are not limited to such applications. 
     As illustrated the endoscopic tool  6502  includes an endoscope body  6504  from which a catheter  6506  may be extended. The endoscopic tool  6502  further includes a snare  6508  disposed within and extending from the catheter  6506 . As illustrated, the snare  6508  includes a loop  6510  which may be used to encircle and capture the polyp  6503  for subsequent removal. The snare  6508  of  FIG. 65  is provided merely as a non-limiting example of an endoscopic tool. It should be understood that the present disclosure is equally applicable to other tools including, without limitation, biopsy forceps, brushes, rods, guidewires, or any other tool that may be delivered via the endoscopic tool  6502  for any purpose. 
     As illustrated in Detail D, at least a portion of the snare  6508  includes texturing  6512  configured to increase frictional engagement between the snare  6508  and an inner wall  6505  of the physiological lumen  6501 . In the specific example illustrated, the texturing  6512  is in the form of a series of protrusions extending from the snare  6508  and disposed proximal to the loop  6510 ; however, it should be understood that any suitable texturing applied at any location along an endoscopic tool may be used instead. 
     During use, a physician or technician may extend the snare  6508  from the catheter  6506  and position the snare  6508  such that the texturing  6512  contacts the inner wall  6505  of the physiological lumen  6501 . Such contact between the texturing  6512  and the inner wall  6505  adheres the snare  6508  to the inner wall  6505 , thereby stabilizing the snare  6508 . In certain implementations, the physician or technician may advance, retract, or otherwise manipulate the snare  6508  once adhered to the inner wall  6505  to manipulate the physiological lumen (e.g., to improve visibility of an area of interest or to move tissue to make biopsy or tissue removal easier). 
       FIG. 66  is a schematic illustration of an operational environment  6600  including a physiological lumen  6601  in which an endoscopic tool  6602  is disposed. For purposes of the current example, the physiological lumen  6601  is assumed to include a polyp  6603  which is to be removed; however, it should be appreciated that implementations of the current disclosure are not limited to such applications. 
     As illustrated the endoscopic tool  6602  includes an endoscope body  6604  from which a catheter  6606  may be extended. The endoscopic tool  6602  further includes a snare  6608  disposed within and extending from the catheter  6606 . As illustrated, the snare  6608  includes a loop  6610  which may be used to encircle and capture the polyp  6603  for subsequent removal. Similar to the previous discussion, the snare  6608  is provided merely as a non-limiting example of an endoscopic tool. 
     As illustrated in Detail E, at least a portion of the catheter  6606  includes texturing  6612  configured to increase frictional engagement between the catheter  6606  and an inner wall  6605  of the physiological lumen  6601 . In the specific example illustrated, the texturing  6612  is in the form of a series of protrusions extending from a distal portion of the catheter  6606 ; however, it should be understood that any suitable texturing applied at any location along the catheter  6606  may be used instead. 
     During use, a physician or technician may extend the catheter  6606  from the endoscopic tool  6602  and position the catheter  6606  such that the texturing  6612  contacts the inner wall  6605  of the physiological lumen  6601 . Such contact between the texturing  6612  and the inner wall  6605  adheres the catheter  6606  to the inner wall  6605 , thereby stabilizing the catheter  6606 . The snare  6608  may then be advanced, retracted, or otherwise manipulated relative to the catheter  6606  to perform a given procedure. 
     The foregoing implementations are intended merely as examples and, as a result, should be viewed as non-limiting. More generally, the present disclosure is directed to catheters and endoscopic tools including texturing adapted to adhere the catheter and/or tool to tissue. In certain implementations, the texturing may be in accordance with specific examples of texturing discussed herein; however, implementations of the present disclosure are not necessarily limited to such specific examples. Moreover, texturing may be applied to the tool/catheter using any suitable technique. For example and without limitation, texturing may be integrally formed on the tool/catheter, may be applied as an outer layer or coating, or may be formed onto the tool/catheter (e.g., by overmolding or spray deposition). 
     Textured Stents 
     In yet another aspect of the present disclosure, textured stents are provided that improve anchoring of such stents, reducing potential for migration and additional interventions associated with repositioning or otherwise adjusting a stent. 
     In one specific implementation, a stent is provided for use in ducts, such as the biliary and pancreatic duct. In biliary and pancreatic duct applications, stents may be temporarily or permanently anchored to force open the duct to facilitate proper drainage into the gastrointestinal tract. For a variety of reasons, biliary and pancreatic ducts can become inflamed and be forced shut due to such inflammation. Accordingly, stents are commonly placed to allow the ducts to drain while the inflamed tissue is healed. However, as previously noted, stent migration can present a significant challenge. 
       FIG. 67  is an example stent  6700  for use in duct-related applications with various features for improving anchoring relative to the duct. As shown in  FIG. 67 , the stent  6700  includes a tubular body  6702  which may optionally terminate in flared ends, hooks, barbs, or similar retention structures  6704 A,  6704 B. However, in certain implementations, the retention structures  6704 A,  6704 B may be omitted in favor of the other retention features discussed below. 
     As illustrated, the stent body  6702  may include texturing along its length. Such texturing may be applied along substantially the entire length of the body  6702  or along certain segments of the body  6702 . For example, the stent  6700  illustrated in  FIG. 67  includes three separate textured segments  6706 A-C. Texturing is also applied to each of the end retention structures  6704 A,  6704 B. In use, the texturing on the stent  6700  improves anchoring by increasing friction/adhesion between the stent  6700  and a physiological lumen or structure within which the stent  6700  is inserted. 
     In certain implementations, the texturing may be integral to the stent body  6702 . For example, the stent  6700  may be molded using silicone or other polymer materials with the texturing included on the surface as part of the molding process. In other implementations, the body  6702  may be initially formed without texturing and the texturing may be applied afterwards. For example, texturing may be applied by applying a layer or coating to the body  6702  including the texturing, overmolding the texturing onto the body  6702 , or spraying the texturing onto the body  6702 , among other manufacturing approaches. 
     The stent  6700  may be fabricated from various materials, each of which may have a durometer suitable for one or more specific applications. The stent  6700  may also be formed from multiple materials. For example, certain sections of the stent  6700  may be formed from relatively a low durometer material to facilitate bending of the stent  6700  while other sections may be formed from a relatively high durometer material to provide localized structural integrity. In another example implementation, the stent  6700  may include multiple layers with an interior layer of the stent  6700  having a higher durometer than exterior layers. In still another example implementation, the stent body  6702  may be formed from a first material having a first durometer while the textured portions or texturing applied to the body  6702  may have a second durometer. 
     The texturing of the stent  6700  may take various forms including, but not limited to, the various example texturing patterns discussed herein. 
     In another implementation of the present disclosure, a textured stent for implantation within a physiological lumen is provided. Such stents may be used, for example, within the gastrointestinal tract or vasculature of a patient. 
     Similar to the previously discussed stents, conventional gastrointestinal and vascular stents may migrate after being placed. Accordingly, placement and anchoring of such stents typically includes the use of sutures to hold the stents in place and/or mechanisms that apply outwardly radial loading to the stent such that it is maintained against the vascular or GI wall. In either case, placement of the stent and prevention of migration results in additional steps and procedures that may increase surgery time and/or raise the possibility of additional complications during implantation of the stent. 
     To address the foregoing issues, among others, the present disclosure includes a textured stent for implantation within a physiological lumen. The stents include an expandable body (e.g., an expandable mesh) that may be covered (entirely or in part) with a textured surface for increasing frictional engagement/adhesion between the stent and the inner wall of the physiological lumen. 
       FIGS. 68A-68C  illustrate an example process of implanting a textured stent  6800 . Referring first to  FIG. 68A , the textured stent  6800  may be disposed on a deployment tool  6802  in a first, compressed configuration. The deployment tool  6802  may then be advanced within the physiological lumen  6801  to position the stent  6800  at an implantation location. 
     When located, the stent  6800  may be deployed by expanding the stent  6800  such that its surface contacts an inner surface  6803  of the physiological lumen  6801 . Although other deployment methods may be implanted, in the illustrated example, the deployment tool  6802  includes an expandable balloon  6806  that is inflated to expand the stent  6800  to contact the inner surface  6803  (as shown in  FIG. 68B ). When expanded, the textured surface of the stent  6800  abuts the inner surface  6803 , with the texturing providing increased friction and adhesion as compared to conventional, smooth stents. 
     Following deployment of the stent  6800 , the balloon  6806  may be deflated and removed from within the physiological lumen  6801 , leaving the stent  6800  in place (as shown in  FIG. 68C ). 
     As previously noted, the texturing may be applied to some or the entire exterior surface of the stent  6800 . For example, in certain implementations, texturing may be applied in one or more circumferential bands that extend about the stent  6800 . In another implementation, texturing may be applied to discrete sections or blocks distributed about the exterior surface of the stent  6800 . 
     Similar to the previous stent, the texturing may be integrally formed with the body of the stent  6800  or may be added in a subsequent process (e.g., by applying a layer or coating, overmolding, etc.). 
     As discussed in the context of the balloons, above, the texturing of the stent  6800  may be configured to have different frictional/adhesion properties in different configurations. For example, when in the compressed configuration illustrated in  FIG. 68A , the texturing may have a relatively low friction coefficient to prevent or minimize adhesion to the physiological lumen during deliver of the stent  6800 . However, in response to the strain applied during deployment of the stent  6800 , the friction coefficient of the texturing may increase to facilitate anchoring of the stent  6800  within the physiological lumen. 
       FIG. 69  is a schematic illustration of another stent  6900  according to the present disclosure. As illustrated, the stent  6900  includes a body  6902  having a tapered tip  6904 . Such stents may be used to facilitate fluid in the bile duct. Similar to the previously discussed stents, the stent body  6902  may be at least partially textured such that when implanted, the texturing of the stent body  6902  frictionally engages/adheres to the wall of a physiological lumen or other tissue, thereby resisting migration of the stent  6900  following implantation. Although the diameter of the stent body  6902  may vary, in at least one implementation the stent body  6902  tapers from a first diameter of approximately 10 Fr down to a second diameter of approximately 8.5 Fr. In certain implementations, the tapered tip  6904  may be reduced to allow use of a pusher catheter  6908  (as described below) but may include a hole or lumen through which a guidewire may be passed. 
     In certain implementations, the body  6902  may define one or more ports or openings, along its length to permit fluid. For example, in the implementation at least one implementation, multiple ports  6906 A- 6906 E may be distributed along the length of the body  6902  in a spiral/helical arrangement. In one specific implementation, the spacing of the ports  6906 A- 6906 E may be approximately 1 cm. 
     Although stent  6900  may be advanced/implanted using various techniques, in at least one approach, a pusher catheter  6908  is inserted into the stent body  6902  and made to abut the inside of the tapered tip  6904 . The stent  6900  may then be pushed from the proximal end using the pusher catheter  6908 . 
     Laparoscopic and Similar Surgical Tools 
     As another example application, texturing in accordance with the present disclosure may be applied in the context of laparoscopic tools. For example,  FIG. 70  illustrates an operational environment  7000  and, in particular a cross-sectional view of a patient abdomen  7002  including an abdominal wall  7004  and abdominal organs  7006 . 
     The operational environment  7000  further includes a pair of surgical tool assemblies  7008 A,  7008 B, which in the particular example of  FIG. 70 , are manually operated laparoscopic tool assemblies. The surgical tool assembly  7008 A includes a trocar/port assembly  7010 A, which may extend through the abdominal wall  7004  to provide access to the internal abdominal cavity  7005 , which, in the case of laparoscopic procedures, may be insufflated during surgery. The surgical tool assembly  7008 A further includes a surgical tool  7012 A including a tool shaft  7014 A terminating in a tool end effector  7016 A. The surgical tool assembly  7008 B similarly includes a surgical tool  7012 B including a tool shaft  7014 B terminating in a tool end effector  7016 B. For clarity and simplicity, the following discussion refers only to surgical tool assembly  7008 A, however, the description of surgical tool assembly  7008 A is generally applicable to surgical tool assembly  7008 B. 
     As discussed below in further detail, at least a portion of the surgical tool  7012 A may include a textured surface in accordance with the present disclosure. For example, one or both of the tool shaft  7014 A and the tool end effector  7016 A may be at least partially textured as described herein. Among other things, such texturing may facilitate manipulation and/or retention of tissue and organs of the abdomen. For example and as illustrated in  FIG. 70 , during surgery, the tool shaft  7014 A may be made to move aside or hold an internal organ. Texturing applied to the tool shaft  7014 A may generally increase grip/adhesion between the tool shaft  7014 A and the tissue/organ, thereby improving the degree of control over the tissue/organ and reducing the likelihood that the tissue/organ will slip from the tool shaft  7014 A. As previously noted, texturing may also or alternatively be applied to the tool end effector  7016 A to similarly increase adhesion and retention of the tool end effector  7016 A. 
       FIGS. 71 and 72  illustrate different implementations of the surgical tool  7012 A and, in particular, different approaches to texturing the surgical tool  7012 A. Referring first to  FIG. 65 , the surgical tool  7012 A is shown as having a first textured portion  7020  disposed along the tool shaft  7014 A and a second textured portion  7022  corresponding to the tool end effector  7016 A. 
     The first textured portion  7020  may be formed in various ways. For example and without limitation, in at least certain implementations, the textured portion  7020  may be integrally formed with the tool shaft  7014 A. In other examples, the textured portion  7020  may be overmolded onto the tool shaft  7014 A. In still other implementations, the textured portion  7020  may be a separate segment of the tool shaft  7014 A that is inserted between and coupled to a proximal and/or distal segment of the tool shaft  7014 A. In yet other implementations, the textured portion  7020  may be formed by applying a coating or similar treatment onto the tool shaft  7014 A. 
     The second texture portion  7022  corresponding to the tool end effector  7016 A may similarly be integrally formed with the tool end effector  7016 A or formed onto the tool end effector  7016 A, such as by overmolding or coating of the tool end effector  7016 A. Although illustrated in  FIG. 70  as being applied to the entire tool end effector  7016 A, texturing may alternatively be applied to only a portion of the tool end effector  7016 A. For example and without limitation, in one application, texturing may only be applied to a proximal surface of the tool end effector  7016 A. In another example implementation in which the tool end effector  7016 A is a grasper-type tool including jaws, texturing may be applied only to the inner surface of the jaws. 
       FIG. 72  is an alternative implementation of the surgical tool  7012 A in which a textured cover  7024  is disposed on the tool shaft  7014 A. In certain implementations, the textured cover  7024  may be a sheath through which the tool shaft  7014 A is inserted, the exterior surface of the sheath having texturing as described herein. The sheath may then be adhered to, shrunk onto, or otherwise retained on the tool shaft  7014 A. In an alternative implementation, the textured cover  7024  may be in the form of a wrap, tape, etc. that is wrapped around the tool shaft  7014 A. To retain the wrap/tape, an adhesive may be applied to the tool shaft  7014 A or the wrap/tape prior to wrapping. Alternatively, the wrap/tape may have an adhesive backing. 
     Although illustrated in  FIGS. 70-72  as manually-operated laparoscopic tools, implementations of the present disclosure may include actuated tools including robotically controlled tools. The various aspects of  FIGS. 70-72  are also not limited to the grasper-type tools illustrated and application of the described texturing to other tools, including other laparoscopic tools and other non-laparoscopic tools, is contemplated. 
     In certain stent applications, texturing of stents according to the present disclosure may include protrusions, ridges, or similar structures that extend outwardly from the exterior surface of the stent. In certain implementations, such protrusions extend in a substantially radial direction. However, in other implementations, at least a portion of the texturing may be swept or otherwise biased toward an end of the stent. By doing so, the texturing may provide additional resistance to movement in the direction of the bias while providing reduced resistance in the opposite direction. So, for example, a stent may include texturing that is backswept in a direction opposite a direction of advancement such that the friction provided by the texturing is reduced during insertion and advancement but increased in a direction opposite that of advancement following deployment (e.g., to counter potential movement caused by blood flow, peristalsis, etc.). Biased texturing and control of such biasing (e.g., by selectively expanding or compressing the stent to vary the angle of the texturing) may also facilitate removal of the stent as it allows physicians and technicians to dynamically modify the resistance/adhesion provided by the texturing. 
     In at least some implementations of stents according to the present disclosure, texturing of the stent may include applying texturing to a metallic or similar substrate. For example texturing of a tubular or expandable metallic stent may be applied by coating the substrate, applying an adhesive layer including the texturing to the substrate, spraying texturing onto the substrate, overmolding texturing onto the substrate, or any other suitable method of applying the texturing to the substrate. 
     It should be understood that the principles discussed in the foregoing disclosure may be combined in ways not explicitly identified above. For example, the various aspects of textures (e.g., dimensions, material, spacing, strain-response, etc.) discussed in the context of endoscopic balloons may be applied to any of the other components discussed herein (e.g., endoscopes, overtubes, endoscopic tools, stents, etc.). As a result, to the extent a given feature, such as texturing, is described with respect to a particular application or component, any such description should be considered to be equally applicable to any other similar feature discussed herein. 
     The present disclosure is further directed to kits including medical devices in accordance with the present disclosure. In certain implementations, the kit includes an endoscope or similar medical device including at least one inflatable balloon having protrusions as described herein. In other implementations, the kit further includes a catheter including a balloon having protrusions as described herein. In yet other implementations, the kit includes instructional materials detailing methods of using medical devices in accordance with the present disclosure. In still another implementation, the kit includes each of an endoscope and a catheter, each of which includes a balloon as described herein. In still other implementations, the kit includes instructional materials detailing methods of using the endoscope and the catheter. 
     As used herein, each of the following terms has the meaning associated with it in this section. 
     As used herein, unless defined otherwise, all technical and scientific terms generally have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Generally, the nomenclature used herein is those well-known and commonly employed in the art. 
     As used herein, the articles “a” and “an” refer to one or to more than one (i.e. to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element. 
     As used herein, the term “about” will be understood by persons of ordinary skill in the art and will vary to some extent on the context in which it is used. As used herein, “about” when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of ±20% or ±10%, more preferably ±5%, even more preferably ±1%, and still more preferably ±0.1% from the specified value, as such variations are appropriate to perform the disclosed methods. 
     As used herein, the term “instructional material” includes a publication, a recording, a diagram, or any other medium of expression that may be used to communicate the usefulness of the compositions and/or methods of the present disclosure. The instructional material of the kit may, for example, be affixed to a container that contains the compositions of the present disclosure or be shipped together with a container that contains the compositions. Alternatively, the instructional material may be shipped separately from the container with the intention that the recipient uses the instructional material and the compositions cooperatively. For example, the instructional material is for use of a kit; and/or instructions for use of the compositions. 
     Throughout this disclosure, various aspects of the present disclosure may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the present disclosure. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range and, when appropriate, partial integers of the numerical values within ranges. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 2.7, 3, 4, 5, 5.3, and 6. This applies regardless of the breadth of the range. 
     Every formulation or combination of components described or exemplified can be used to practice implementations of the current disclosure, unless otherwise stated. Specific names of compounds are intended to be exemplary, as it is known that one of ordinary skill in the art can name the same compounds differently. When a compound is described herein such that a particular isomer or enantiomer of the compound is not specified, for example, in a formula or in a chemical name, that description is intended to include each isomers and enantiomer of the compound described individual or in any combination. 
     Although the description herein contains many example implementations, these should not be construed as limiting the scope of the current disclosure but as merely providing illustrative examples. 
     All references throughout this disclosure (for example, patent documents including issued or granted patents or equivalents; patent application publications; and non-patent literature documents or other source material) are hereby incorporated by reference herein in their entireties, as though individually incorporated by reference, to the extent each reference is at least partially not inconsistent with the disclosure in this application (for example, a reference that is partially inconsistent is incorporated by reference except for the partially inconsistent portion of the reference). 
     Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific procedures, embodiments, claims, and examples described herein. Such equivalents were considered to be within the scope of this disclosure and covered by the claims appended hereto. In general the terms and phrases used herein have their art-recognized meaning, which can be found by reference to standard texts, journal references, and contexts known to those skilled in the art. Any preceding definitions are provided to clarify their specific use in the context of the present disclosure. 
     It is to be understood that wherever values and ranges are provided herein, all values and ranges encompassed by these values and ranges, are meant to be encompassed within the scope of the present disclosure. Moreover, all values that fall within these ranges, as well as the upper or lower limits of a range of values, are also contemplated by the present disclosure. 
     The disclosures of each and every patent, patent application, and publication cited herein are hereby incorporated herein by reference in their entirety. 
     While this disclosure includes reference to specific embodiments, it is apparent that other embodiments and variations of this disclosure may be devised by others skilled in the art without departing from the true spirit and scope of the disclosure. The appended claims are intended to be construed to include all such embodiments and equivalent variations.