Patent Publication Number: US-2022219194-A1

Title: Coating application system and methods for coating rotatable medical devices

Description:
This application claims the benefit of U.S. Provisional Application No. 63/135,279, filed Jan. 8, 2021, the content of which is herein incorporated by reference in its entirety. 
    
    
     FIELD 
     Embodiments herein relate to a system for coating rotatable medical devices. 
     BACKGROUND 
     Functional improvements to implantable or insertable medical devices can be achieved by coating the surface of the device. For example, a coating formed on the surface of the device can provide improved lubricity, improved biocompatibility, or drug delivery properties to the surface. In turn, this can improve movement of the device in the body, extend the functional life of the device, or treat a medical condition near the site of implantation. However, various challenges exist for the design and use of coating apparatus designed to provide coatings to medical devices. 
     Traditional coating methods, such as dip coating, are often undesirable as they may result in flawed coatings that could compromise the function of the device or present problems during use. These methods can also result in coating inaccuracies, which can be manifested in variable amounts of the coated material being deposited on the surface of the device. When a drug is included in the coating material, it is often necessary to deliver precise amounts of the agent to the surface of the device to ensure that a subject receiving the coated device receives a proper dose of the agent. It has been difficult to achieve a great degree of accuracy using traditional coating methods and machines. 
     SUMMARY 
     Embodiments herein relate to a system for coating rotatable medical devices and related methods. In an embodiment, a coating system for coating rotatable medical devices is included having a rotation mechanism, wherein the rotation mechanism is configured to mount and rotate a rotatable medical device. The coating system also includes a fluid applicator unit. The fluid applicator unit can include a rotating retention sleeve. The rotating retention sleeve can define a channel into which the rotatable medical device or a component thereof fits during a coating operation. 
     In an embodiment, a method of coating a rotatable medical device is included. The method can include fitting the rotatable medical device within a rotating retention sleeve of a fluid applicator unit. The method can also include rotating the rotatable medical device with a rotation mechanism. The method can also include rotating the rotating retention sleeve at a speed matching the rotation speed of the rotatable medical device. The method can also include moving a fluid applicator tip and the rotating retention sleeve together relative to a lengthwise axis of the rotatable medical device. The method can also include applying a coating solution onto a surface of the rotatable medical device using the fluid applicator tip, wherein an outside diameter of a component of the rotatable medical device to be coated matches an inside diameter of a channel of the rotating retention sleeve. 
     This summary is an overview of some of the teachings of the present application and is not intended to be an exclusive or exhaustive treatment of the present subject matter. Further details are found in the detailed description and appended claims. Other aspects will be apparent to persons skilled in the art upon reading and understanding the following detailed description and viewing the drawings that form a part thereof, each of which is not to be taken in a limiting sense. The scope herein is defined by the appended claims and their legal equivalents. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Aspects may be more completely understood in connection with the following figures (FIGS.), in which: 
         FIG. 1  is a schematic view of a balloon catheter being coated in accordance with various embodiments herein. 
         FIG. 2  is a schematic view of an inner collar in accordance with various embodiments herein. 
         FIG. 3  is a cross-sectional view of an inner collar as taken along line  3 - 3 ′ of  FIG. 2  in accordance with various embodiments herein. 
         FIG. 4  is a schematic view of an inner collar fit over a shaft of a balloon catheter in accordance with various embodiments herein. 
         FIG. 5  is a schematic view of a rotating sleeve in accordance with various embodiments herein. 
         FIG. 6  is a cross-sectional view of a rotating sleeve as take along line  6 - 6 ′ of  FIG. 5  in accordance with various embodiments herein. 
         FIG. 7  is a schematic view of a rotating sleeve fit over a balloon catheter in accordance with various embodiments herein. 
         FIG. 8  is a partial sectional view of a balloon catheter being coated in accordance with various embodiments herein. 
         FIG. 9  is a schematic view of a fluid applicator unit in accordance with various embodiments herein. 
         FIG. 10  is a schematic view of a fluid applicator unit in accordance with various embodiments herein. 
         FIG. 11  is a schematic view of a coating application system in accordance with various embodiments herein. 
         FIG. 12  is a schematic view of a fluid applicator unit in accordance with various embodiments herein. 
     
    
    
     While embodiments are susceptible to various modifications and alternative forms, specifics thereof have been shown by way of example and drawings, and will be described in detail. It should be understood, however, that the scope herein is not limited to the particular aspects described. On the contrary, the intention is to cover modifications, equivalents, and alternatives falling within the spirit and scope herein. 
     DETAILED DESCRIPTION 
     Coatings are frequently applied onto the surfaces of various medical devices including, but not limited to, catheters and particularly balloon catheters. It is typically desirable for such coatings to be as uniform as possible in terms of thickness, composition, and the like. However, in some cases, a rollable (or rotatable) medical device may wobble as it is being rotated during the coating process. For example, catheters generally exhibit significant longitudinal flexibility that is consistent with their intended use. However, when rotated around their lengthwise axis, this can result in a noticeable wobble. This wobble can create challenges for forming a uniform coating. For example, in the context of a coating process that includes a direct contact or near-contact coating applicator the wobble can result in variation of the coating applicator with respect to the surface of the medical device being coated leading to non-uniform coatings being deposited. 
     However, embodiments herein can be used to apply uniform coatings, such as coatings including active agents, onto various medical devices, such as onto the balloons of drug coated or drug eluting balloon catheters. In specific, embodiments herein can minimize the amount of wobble that a medical device may exhibit while being rotated during a coating application process promoting the application of a uniform coating layer thereon. Minimizing the amount of wobble can be valuable in many coating scenarios but can be particularly valuable in the case of coating systems utilizing a direct contact coating tip. 
     In various embodiments, wobble can be reduced or eliminated through the use of a rotating retention sleeve, which can rotate at a speed approximating the speed of rotation of the rotating medical device (by virtue of being driven at that speed or freely rotating under the influence of the rotatable medical device). Because the rotating retention sleeve can rotate at approximately the same speed as the rotatable medical device, the amount of friction and other forces between the rotating retention sleeve and the rotatable medical device can be minimized to prevent any inadvertent damage to the rotatable medical device and portions thereof such as a balloon as well as limiting the inadvertent creation of particulates that may otherwise be formed through frictional wear. 
     Referring now to  FIG. 1 , a schematic view of a balloon catheter  100  being coated is shown in accordance with various embodiments herein. The balloon catheter  100  serves as merely on example of a rotatable medical device herein. Many further examples of exemplary medical devices are provided below. The balloon catheter  100  includes a shaft  102  and a balloon  104  disposed on the shaft  102 . The shaft  102  includes a distal end  106  and a proximal end  108 . A fluid applicator tip  110  is shown as it may be positioned for the application of a coating fluid or coating solution. The coating fluid or coating solution can be applied to a balloon catheter to produce a drug-coated balloon useful for various types of therapeutic intervention. 
     In various embodiments, the fluid applicator tip  110  can be configured to contact a surface of the balloon catheter  100 , which a coating fluid passing out of the fluid applicator tip  110  and onto the surface of the balloon  104 . The balloon catheter  100  can be rotated as the fluid applicator tip  110  is move along the lengthwise axis of the balloon catheter  100 . As such, the pattern of deposition of the coating solution generally resembles a helical or spiral pattern. A mandrel  112  can be used to hold the balloon catheter  100  as it rotates. 
     However, when the balloon catheter  100  is being rotated it can exhibit oscillations, as illustrated in  FIG. 1 , where it moves slightly in a direction that is lateral to the lengthwise axis the balloon catheter  100 . Such oscillations are referred to herein as “wobble”. This wobble can be detrimental to providing a uniform coating. 
     Devices and systems herein can include various components that can limit or eliminate any substantial wobble of a rotatable medical device as it is being coated. One component of the system can be an inner collar. Referring now to  FIG. 2 , a schematic view of an inner collar  202  is shown in accordance with various embodiments herein. As shown in  FIG. 2 , the inner collar  202  can define a channel (as shown in  FIG. 3 ) and can fit over the mandrel  112  and/or over the shaft of a balloon catheter  100 . In some embodiments, the inner collar  202  can be slide over the mandrel  112  and/or the shaft of the balloon catheter  100  and come to rest against or adjacent to the balloon  104  of the balloon catheter  100 . 
     The inner collar  202  itself can within a channel of a rotating retention sleeve (described further below). The functionality of the inner collar  202  with respect to the rotating retention sleeve is described in greater detail below. The inner collar  202  can be formed of many different materials. In some embodiments, the inner collar  202  can include a polymer, a metal, a glass, a ceramic or a composite. An outside diameter of the inner collar  202  can approximately match an outside diameter of the balloon  104  of the balloon catheter  100  or an outside diameter of another component of a medical device to be coated. In some embodiments, an outside diameter of the inner collar  202  can be within 50, 40, 30, 20, 10, 5, 2.5, or 1 percent of the size of an outside diameter of the balloon  104  of the balloon catheter  100  or an outside diameter of another component of a medical device to be coated. 
     As used herein the terms “match” or “approximately match” with respect to a diameter size shall refer to one diameter being within 25 percent of the size of another diameter. As used herein the terms “match” or “approximately match” with respect to a rotation speed shall refer to one speed being within 25 percent of another speed. 
     Referring now to  FIG. 3 , a cross-sectional view of an inner collar  202  as taken along line  3 - 3 ′ of  FIG. 2  is shown in accordance with various embodiments herein. The inner collar  202  defines a collar channel  304  into which a shaft of a rotatable medical device can fit. 
     Therefore, the collar channel  304  can be sufficiently large to fit a mandrel used to support the rotatable medical device during a coating operation. The mandrel can be of various sizes. In some embodiments, the outside diameter of a shaft of a rotatable medical device can vary. In some embodiments, the outside diameter can be greater than or equal to 0.5, 1, 2, 3, or 4 mm. In some embodiments, the outside diameter can be less than or equal to 6, 4, or 2 mm. In some embodiments, the outside diameter can fall within a range of 0.5 to 6 mm, or 0.5 to 4 mm, or 0.5 to 2 mm. Reciprocally, the inside diameter of the collar channel  304  can vary. In some embodiments, the inside diameter can be greater than or equal to 0.5, 1, 2, 3, or 4 mm. In some embodiments, the inside diameter can be less than or equal to 6, 4, or 2 mm. In some embodiments, the inside diameter can fall within a range of 0.5 to 6 mm, or 0.5 to 4 mm, or 0.5 to 2 mm. 
     In some embodiments, the inner collar  202  also includes a contoured mouth  306  exhibiting a generally concave shape. The contoured mouth  306  can allow the inner collar  202  to fit more closely up against the balloon  104  of the balloon catheter  100 . However, in some embodiments, the contoured mouth  306  can be omitted. 
     Referring now to  FIG. 4 , a schematic view of an inner collar  202  fit over a shaft  102  of a balloon  104  catheter is shown in accordance with various embodiments herein. The shaft includes a distal end  106  and a proximal end  108 . The inner collar  202  can be fit over either the distal end  106  or the proximal end  108 , depending on various factors such as the direction that the coating process will proceed (e.g., starting from the distal end or from the proximal end). Generally, the inner collar  202  is positioned on the downstream side of the balloon during the coating operation (e.g., if the coating is applied starting on the proximal side, then the inner collar  202  can be positioned on the distal side. The inner collar  202  can fit up against the side or edge of the balloon  104 . In some embodiments, the inner collar  202  can be secured to the balloon catheter. However, in some embodiments the inner collar  202  fits over the shaft of the balloon catheter, but is not secured thereto. 
     In various embodiments, the inner collar  202  can work in conjunction with a rotating sleeve in order to prevent or eliminate wobble of the rotatable medical device. However, in some embodiments, the inner collar can be omitted and the system can rely upon the rotating sleeve in order to prevent or eliminate wobble. 
     Referring now to  FIG. 5 , a schematic view of a rotating retention sleeve  502  is shown in accordance with various embodiments herein. The rotating retention sleeve  502  can be formed of many different materials. In some embodiments, the rotating retention sleeve  502  can include a polymer, a metal, a glass, a ceramic, or a composite. 
     Referring now to  FIG. 6 , a cross-sectional view of the rotating retention sleeve  502  as taken along line  6 - 6 ′ of  FIG. 5  is shown in accordance with various embodiments herein. As can be seen, the rotating retention sleeve  502  can define a channel  604 . 
     In various embodiments, a rotatable medical device  100  and/or portions thereof can fit within the channel  604 . In specific, the channel  604  can be sufficiently large to fit a balloon  104  of the rotatable medical device  100  therein along with, if present, an inner collar  202 . It will be appreciated, however, that medical devices can be coated herein beyond just those including balloons. As such, in some embodiments, the channel  604  can be sufficiently large to fit a component to be coated of the rotatable medical device  100  therein along with, if present, an inner collar  202 . 
     The balloons of medical devices herein (in the case of coating medical device including balloons) can have an outside diameter of various dimensions. In some embodiments, the outside diameter can be greater than or equal to 0.5, 1, 2, 4, 6, 8, 10, 12, 14, 17, 20, 23, or 26 mm. In some embodiments, the outside diameter can be less than or equal to 35, 30, 26, 23, 19, 16, or 12 mm. In some embodiments, the outside diameter can fall within a range of 0.5 to 30 mm, 0.5 to 26 mm, or 2 to 12 mm. Reciprocally then, the inner diameter of the channel  604  of the rotating retention sleeve can be greater than or equal to 0.5, 1, 2, 4, 6, 8, 10, 12, 14, 17, 20, 23, or 26 mm. In some embodiments, the inner diameter can be less than or equal to 35, 30, 26, 23, 19, 16, or 12 mm. In some embodiments, the inner diameter can fall within a range of 0.5 to 30 mm, 0.5 to 26 mm, or 2 to 12 mm. In some embodiments, the outside diameter of the balloon or other component to be coated can be within 40, 30, 20, 10, 5, 2.5, or 1 percent of the size of the inner diameter of the channel  604 . 
     Referring now to  FIG. 7 , a schematic view of a rotating sleeve fit over a balloon catheter  100  is shown in accordance with various embodiments herein. The shaft of the balloon catheter  100  includes a distal end  106  and a proximal end  108 . The rotatable medical device also includes a balloon  104 . The inner collar  202  of the coating system fits over the shaft of the balloon catheter  100 . In turn, both the inner collar  202  and the balloon catheter  100  fit within the rotating retention sleeve  502  and can slide therein. 
     In operation, a rotatable medical device can be rotated during a coating operation. The rotating retention sleeve can, in turn, can be rotated at a speed that approximately matches a rotation speed of the rotatable medical device. By virtue of the rotatable medical device fitting within a channel of the rotating retention sleeve, the rotating retention sleeve can physically limit the amount of wobble that is possible for the rotatable medical device to undergo. The coating applicator tip trails behind the rotating retention sleeve as both move along the lengthwise axis of the rotatable medical device. Because the rotating retention sleeve can rotate at a speed approximating the speed of rotation of the rotating medical device (by virtue of being driven at that speed or freely rotating under the influence of the rotatable medical device), the amount of friction and other forces between the rotating retention sleeve and the rotatable medical device can be minimized to prevent any inadvertent damage to the rotatable medical device and portions thereof such as a balloon. 
     Referring now to  FIG. 8 , a partial sectional view of a balloon  104  catheter being coated is shown in accordance with various embodiments herein. As before, the balloon catheter can include a shaft with a distal end  106  and a proximal end  108  as well as a balloon  104 . In this view, the balloon  104  includes a coated portion  802  and an uncoated portion  804 . 
     The coating system includes an inner collar  202 , a rotating retention sleeve  502 , and a fluid applicator tip  110 . The rotating retention sleeve  502  defines a channel  604  into which balloon catheter  100  fits, physically limiting the amount of wobble that the balloon catheter  100  can undergo. The fluid applicator tip  110  trails behind the rotating retention sleeve  502  as both move along the lengthwise axis of the balloon catheter  100 . As the balloon catheter  100  exits the channel of the rotating retention sleeve  502 , the smaller diameter of the shaft versus the balloon allows for more lateral play of the balloon catheter relative to the rotating retention sleeve  502 . However, because of the inner collar  202 , the lateral play is effectively taken up allowing for the system to control wobble as the fluid applicator tip  110  coats up to the end of the balloon  104  of the balloon catheter  100 . 
     It will be appreciated that coating systems herein can include various other components. Referring now to  FIG. 9 , a schematic view of a fluid applicator unit  900  is shown in accordance with various embodiments herein. In this view, the fluid applicator unit  900  is being used to coat a rotatable medical device including a shaft with a distal end  106  and a proximal end  108  along with a balloon  104 . In this view, the balloon  104  includes a coated portion  802  and an uncoated portion  804 . 
     The fluid applicator unit  900  can include a fluid applicator tip  110  and a rotating retention sleeve  502 . The fluid applicator unit  900  also includes a retention sleeve drive mechanism  904 . The retention sleeve drive mechanism  904  can include an electric motor. In this particular example, the retention sleeve drive mechanism  904  includes a drive belt  906  to transfer power to the rotating retention sleeve  502 . However, in other embodiments, other mechanisms can be used including, but not limited to, drive gears, a drive chain, a drive shaft, and the like. 
     Various components of the fluid applicator unit  900  can be mounted together on a platform  902 . The fluid applicator unit  900  can also include one or more support brackets  908  which can be used to secure the rotating retention sleeve  502  to the rest of the fluid applicator unit  900 , while allowing the rotating retention sleeve  502  to rotate freely as driven by the retention sleeve drive mechanism  904 . In some embodiments, the support brackets can include mechanisms to support the rotating retention sleeve  502  such as bushings or bearings. 
     In various embodiments, the fluid applicator unit  900  can be configured to move relative to a rotatable medical device  100  along a lengthwise axis thereof. The movement can be relative in the sense that in some embodiments, the fluid applicator unit  900  can be configured to move along the lengthwise axis of the rotatable medical device. In some embodiments, the fluid applicator unit  900  can be stationary and the rotatable medical device can move in the direction of its lengthwise axis. In some embodiments, both the fluid applicator unit  900  and the rotatable medical device can move. 
     In some embodiments, the relative speed between the fluid applicator and the rotatable medical device can be greater than or equal to 0.1 mm/s, 0.5 mm/s, 0.9 mm/s, 1.2 mm/s, 1.6 mm/s, or 2.0 mm/s. In some embodiments, the speed can be less than or equal to 30.0 mm/s, 25 mm/s, 20 mm/s, 15 mm/s, 10 mm/s, or 5 mm/s. In some embodiments, the speed can fall within a range of 0.1 mm/s to 30.0 mm/s, or 0.5 mm/s to 25 mm/s, or 0.9 mm/s to 20 mm/s, or 1.2 mm/s to 15 mm/s, or 1.6 mm/s to 10 mm/s. 
     In various embodiments, the retention sleeve drive mechanism  904  can be configured to rotate a rotating retention sleeve  502  at a speed approximately matching a speed of rotation of the medical device being coated as driven by a rotation mechanism (described further below). For example, in various embodiments, the retention sleeve drive mechanism  904  can be configured to rotate a rotating retention sleeve  502  at a speed within 10, 8, 5, 4, 3, 2, 1, or 0.1 percent of the speed of rotation of a rotation mechanism that is rotating the medical device being coated itself. By matching speeds, very little force is exerted on the surface of the medical device by the rotating retention sleeve as the medical device passes therethrough because the rotational speeds are matched. This can serve to prevent inadvertent damage to the medical device during the coating process. 
     The specific rotation speed of the retention sleeve drive mechanism  904  can vary. In some embodiments, the rotation speed can be greater than or equal to 25, 50, 75, 100, 125, or 150 RPM. In some embodiments, the rotation speed can be less than or equal to 1500, 1200, 1000, 750, 500, 400, 350, 300, 250, 200, or 150 RPM. In some embodiments, the rotation speed can fall within a range of 25 to 1500 RPM, or 50 to 1250 RPM, or 100 to 1200 RPM, or 150 to 500 RPM. 
     Referring now to  FIG. 10 , a schematic view of a fluid applicator unit  900  is shown in accordance with various embodiments herein.  FIG. 10  shows a fluid applicator unit  900  consistent with that shown in  FIG. 9 . However, as depicted in  FIG. 10 , the balloon catheter has passed farther through the rotating retention sleeve  502  and a greater portion of the balloon  104  has been coated. 
     Coating systems herein can include various other components. Referring now to  FIG. 11 , a schematic view of a coating application system  1100  is shown in accordance with various embodiments herein.  FIG. 11  shows a rotatable medical device  100  being coated by the coating application system  1100 . 
     The coating application system  1100  includes a fluid applicator unit  900  and rotation mechanism including a first end drive unit  1104  and a second end drive unit  1106 . The first end drive unit  1104  and a second end drive unit  1106  are attached to opposed ends of a rotatable medical device  100 . Each of the first end drive unit  1104  and the second end drive unit  1106  can include an electric motor or another source of power to rotate the rotatable medical device  100 . 
     The first end drive unit  1104  and the second end drive unit  1106  can rotate at various speeds. Generally, the first end drive unit  1104  and the second end drive unit  1106  can be controlled to rotate at the same speed as each other. In some embodiments, the rotation speed can be greater than or equal to 25, 50, 75, 100, 125, or 150 RPM. In some embodiments, the rotation speed can be less than or equal to 1500, 1250, 1000, 750, 500, 400, 350, 300, 250, 200, or 150 RPM. In some embodiments, the rotation speed can fall within a range of 25 to 1500 RPM, or 50 to 1250 RPM, or 100 to 1200 RPM, or 150 to 500 RPM. In some embodiments, however, one of the first end drive unit  1104  and the second end drive unit  1106  can be omitted. For example, one end of the rotatable medical device  100  can be directly driven by a drive unit and the other end can freely rotate without be directly driven. 
     The fluid applicator unit  900  can also include a fluid supply reservoir  1110  and a fluid supply line  1112 , which can convey a coating fluid (described further below) to the coating applicator tip. In some embodiments, a pump (not shown) can also be used to convey coating fluid to the coating applicator tip from the fluid supply reservoir  1110 . 
     The coating application system  1100  also includes a system controller  1102 , which can be used to control operations of the system including, but not limited to, controlling the fluid applicator unit  900  and the rotation mechanism and components thereof. The system controller  1102  can include a processing unit such as a microprocessor, a microcontroller, an ASIC, or the like. 
     The coating application system  1100  can also include a fluid applicator unit conveyor  1108 . The fluid applicator unit conveyor  1108  can be used to move the fluid applicator unit  900  with respect to the longitudinal axis of the rotatable medical device  100  during a coating operation. The fluid applicator unit conveyor  1108  can be of various types. In some embodiments, the fluid applicator unit conveyor  1108  can be a belted unit, a track, a conveyor belt, a linear actuator, or the like. 
     In some embodiments, the rotating retention sleeve may not be driven to rotate (e.g., not driven by a motor). Rather, it can just freely rotate such as supported by bushing, bearings, or the like and through contact with the balloon catheter can assume a rotation speed roughly equal to the rotation speed of the balloon catheter. 
     Referring now to  FIG. 12 , a schematic view of a fluid applicator unit  900  is shown in accordance with various embodiments herein.  FIG. 12  shows a fluid applicator unit  900  that is consistent with that shown in  FIG. 10 . However, in this embodiment, there is no retention sleeve drive mechanism  904  or drive belt  906 . 
     Methods 
     Many different methods are contemplated herein, including, but not limited to, methods of making, methods of using, and the like. Aspects of system/device operation described elsewhere herein can be performed as operations of one or more methods in accordance with various embodiments herein. 
     In an embodiment, a method of coating a rotatable medical device is included, the method can include fitting the rotatable medical device within a rotating retention sleeve of a fluid applicator unit, rotating the rotatable medical device with a rotation mechanism, rotating the rotating sleeve at a speed matching the rotation speed of the rotatable medical device, and moving the fluid applicator relative to a lengthwise axis of the rotatable medical device while applying a coating solution onto a surface of the rotatable medical device using a fluid applicator tip or other fluid applicator. 
     In an embodiment, the method can further include fitting an inner collar over a shaft of the rotatable medical device. 
     In various embodiments of the method, the rotatable medical device comprises a balloon catheter. However, many other medical devices are contemplated herein as described more fully below. 
     Medical Devices 
     It will be appreciated that many different medical devices can be coated using equipment and methods herein. In various embodiments, rotatable medical device can be coated using equipment and methods described herein. In various embodiments, relatively long medical devices (such as those having a length that it is at least 20 times their diameter) can be coated using equipment and methods described herein. 
     One type of medical device is a balloon catheter. Balloon catheter constructions are well known in the art and are described in various documents, for example, U.S. Pat. Nos. 4,195,637, 5,041,089, 5,087,246, 5,318,587, 5,382,234, 5,571,089, 5,776,101, 5,807,331, 5,882,336, 6,394,995, 6,517,515, 6,623,504, 6,896,842, and 7,163,523. Balloon catheters generally include four portions, the balloon, catheter shaft, guide wire, and manifold. A balloon catheter generally includes an elongated catheter shaft with an inflatable balloon attached to a distal section of the catheter shaft. At a proximal end of the catheter shaft, there is typically a manifold. At the manifold end, placement of the catheter can be facilitated using a guide wire. Guide wires are small and maneuverable when inserted into an artery. Once the guide wire is moved to the target location, the catheter with balloon portion is then fed over the guide wire until the balloon reaches the target location in the vessel. The balloon is typically inserted into the arterial lumen of a patient and advanced through the lumen in an unexpanded state. The balloon is then inflated when the catheter reaches target site resulting in application of mechanical force sufficient to cause vessel dilation. The balloon is typically inflated using a fluid, which is injected through an inflation port. The manifold can control the fluid introduction within shaft for expansion of the balloon. The mechanics of fluid transfer and introduction within balloons vary according to the specific design of the catheter, and are well known in the art. 
     Coating Solutions 
     It will be appreciated that coating solutions/fluids/compositions applied onto medical devices herein can include various components including, but not limited to, one or more active agents, carrier agents and/or solvents, polymers (including degradable or non-degradable polymers), cross-linking agents, excipients, and the like. The relative amounts of the components of the coating solution can depend on various factors including the desired amount of active agent to be applied to the balloon and the desired release rate of the active agent. Exemplary coating compositions are described in U.S. Publ. Pat. Appl. No. 2018/0110903, the content of which is herein incorporated by reference. Exemplary cross-linking agents are described in U.S. Pat. No. 8,889,760, the content of which is herein incorporated by reference. 
     In some embodiments, active agents can specifically include those wherein the coating solution is the form of a suspension or emulsion including active agent particles. 
     In some embodiments, the coating solution/fluid/composition can omit an active agent. In some embodiments, the coating solution/fluid/composition can include a hydrophilic polymer. 
     Fluid Applicators 
     It will be appreciated that while the embodiments of the figures shown herein have depicted fluid applicator units including a fluid applicator tip (as an example of a contact-based fluid applicator) many other types of contact-based and non-contact fluid applicators are specifically contemplated herein. For example, fluid applicators herein can include spray nozzles, ultrasonic applicators, plate applicators, ink jets, brushes, and the like. 
     It should be noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. Thus, for example, reference to a composition containing “a compound” includes a mixture of two or more compounds. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. 
     It should also be noted that, as used in this specification and the appended claims, the phrase “configured” describes a system, apparatus, or other structure that is constructed or configured to perform a particular task or adopt a particular configuration. The phrase “configured” can be used interchangeably with other similar phrases such as arranged and configured, constructed and arranged, constructed, manufactured and arranged, and the like. 
     All publications and patent applications in this specification are indicative of the level of ordinary skill in the art to which this invention pertains. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated by reference. 
     As used herein, the recitation of numerical ranges by endpoints shall include all numbers subsumed within that range (e.g., 2 to 8 includes 2.1, 2.8, 5.3, 7, etc.). 
     The headings used herein are provided for consistency with suggestions under 37 CFR 1.77 or otherwise to provide organizational cues. These headings shall not be viewed to limit or characterize the invention(s) set out in any claims that may issue from this disclosure. As an example, although the headings refer to a “Field,” such claims should not be limited by the language chosen under this heading to describe the so-called technical field. Further, a description of a technology in the “Background” is not an admission that technology is prior art to any invention(s) in this disclosure. Neither is the “Summary” to be considered as a characterization of the invention(s) set forth in issued claims. 
     The embodiments described herein are not intended to be exhaustive or to limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art can appreciate and understand the principles and practices. As such, aspects have been described with reference to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope herein.