|Publication number||US20080280025 A1|
|Application number||US 11/431,366|
|Publication date||Nov 13, 2008|
|Filing date||May 9, 2006|
|Priority date||Feb 24, 2006|
|Also published as||DE112007000445T5, US8161902, US20100227045, WO2007100838A2, WO2007100838A3|
|Publication number||11431366, 431366, US 2008/0280025 A1, US 2008/280025 A1, US 20080280025 A1, US 20080280025A1, US 2008280025 A1, US 2008280025A1, US-A1-20080280025, US-A1-2008280025, US2008/0280025A1, US2008/280025A1, US20080280025 A1, US20080280025A1, US2008280025 A1, US2008280025A1|
|Inventors||Ingo Werner Scheer|
|Original Assignee||Ingo Werner Scheer|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (9), Classifications (13)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This Application relates to and claims priority from commonly owned U.S. Provisional Patent Application Ser. No. 60/776,522, filed on Feb. 24, 2006.
1. Field of Invention
This invention relates to a holding device and a method of coating hollow cylindrical objects using the device. More specifically, the present invention provides a holding device and a method of reproducibly and securely supporting and rotating one or more hollow cylindrical objects, such as stents, during a coating process, while minimizing runout of the hollow cylindrical object during rotation and surface contact between the hollow cylindrical object and the holding device.
2. Background of the Invention
Coatings are often applied to medical appliances, such as pacemakers, vascular grafts, stents, and heart valves, to have desired effects and increase their effectiveness. These coatings may deliver a therapeutic agent or drug to the lumen that reduces smooth muscle tissue proliferation or restenosis. Furthermore, medical devices may be coated to provide beneficial surface properties achieving enhanced biocompatibility and to improve surface properties such as lubriciousness. Balloon delivery systems, stent grafts and expandable stents are specific examples of medical appliances or implants that may be coated and inserted within the body. Stents such as described in U.S. Pat. No. 4,733,665, are tiny, expandable mesh tubes supporting the inner walls of a lumen used to restore adequate blood flow to the heart and other organs.
Conventionally, coatings are applied to the stent in a number of ways including, though not limited to, dip coating, spin coating, or spray coating processes. Spray coating processes generally require an apparatus to securely hold and rotate the flexible, tiny stent structure during the coating operation to allow a repeatable and homogeneous coating application of the whole surface.
However, holding devices known from the prior art have several drawbacks which may result in low volume production of medical devices, damage to the fragile stent structure, inhomogeneous coatings, uncoated areas, coating accumulations, and the like. Coating accumulations, such as shown in
Stent holding devices, as described in U.S. Pat. No. 6,605,154, comprising a mandrel passing all the way through the inner hollow body of the stent to support the stent via support members, which partially penetrate into the opposing sides of the hollow body of the stent by incrementally moving at least one support member closer to the other, can have several disadvantages.
When using such stent holding devices there may be a risk of coating defects at the ends of the stent due to the design of the support elements. The clamping force can vary from stent to stent, which may lead to sagging or buckling of the stent. Mandrels having a small diameter and a comparatively long length of approximately 40-80 mm may easily bend resulting in a runout of the stent. Moreover, stent holding devices comprising members projecting out of a body to contact the stent, such as described in U.S. Pat. No. 6,572,644, may not center and secure the stent sufficiently.
Runout, sagging and buckling of the stent may cause an inhomogeneous coating thickness, coating defects on the stent surface and coating weight deviations. Coating consistency may vary from stent to stent depending on runout and positioning accuracy of the support members.
In addition, coating defects, such as uncoated areas on the stent surface, may arise when stent holding devices are used having a structure which interferes with the spray plume, such as described in WO Pat. No. 2004/008995.
Damage of the coating may also occur after competition of the coating process during handling and inspection. Inspection of medical devices generally requires dismounting the stent from the holding device being used during the coating process in order to mount the stent on an inspection fixture which typically contacts the outer surface of the stent.
Finally, stent holding devices known by the prior art are not designed to allow supporting and coating of multiple stents simultaneously or to be used for subsequent inspection of the coated stents.
There is therefore a need for a device and a coating method which will improve the efficiency, stability and reproducibility of the stent coating process by securing the stent during the coating operation without disturbing the coating process, damaging the medical device and/or coating and by permitting higher volume, low cost production of high quality coated medical devices.
Accordingly, a multi-purpose holding device for handling, securing and rotating one or more medical devices and a method to apply motion and coating to one or more medical devices, such as stents, is provided. The holding device includes a rigid frame structure and interchangeable support members to allow precise alignment of the medical device within the frame structure and minimized runout. To avoid coating defects, the holding device does not extend completely through the medical device, provides minimized surface contact with respect to the medical device and does not block the spray plume from uniformly coating the entire stent.
In one embodiment of the present invention, the holding device comprises a frame, which surrounds one or more stents and at least two support members. The support members are bearing mounted to the frame and are in contact with at least a portion of the stent. In a first position, the support members are engaged with the stent at two opposing sides and the stent is securely held and can be rotated in relation to the frame. At least one support member has a second position of being disengaged from the stent. In one or more embodiments, the support members are in contact with the inner surface of the stent in the first position. The support members have a body without structures projecting out of the body. At least a portion of the support members may comprise a polygonal cross-section and the support members may be interchangeable. The holding device of the present invention may further comprise one or more shafts which are bearing mounted to the frame in order to transmit rotary motion to one or more support members. It may also comprise sleeves which are bearing mounted to the frame to connect the support members to the frame, wherein in a first position the support members may be coupled to the sleeve to transmit rotary motion, and in a second position the support members may be uncoupled from the sleeve. The holding device may furthermore comprise members, such as belts, to transmit rotary motion between the shaft and the support member. In addition, one or more guide sections may be included.
In a next embodiment, the holding device includes a frame which surrounds one or more stents and at least two support members which are bearing mounted at a predetermined position to the frame. The support members include a first member having a flexible and sheet-like structure, a second member having a cylindrical shape and a third member. The second member is connected to the first member and comprises an aperture for receiving the third member. In a first position, the third member is located within the inner hollow section of the stent to expand the first member such that the resulting surface of the first member contacts the stent around its entire perimeter. The stent is securely held at two opposing sides and can by rotated in relation to the frame. In a second position, the third member is located outside the hollow section of the stent and the first member is retracted and not in contact with the stent.
In one or more embodiments, the holding device may comprise one or more shafts which are bearing mounted to the frame to transmit rotary motion to one or more support members. In addition, it may include members, such as belts, to transmit rotary motion between the shaft and the support members. Furthermore, one or more guide sections may be included.
In a further embodiment, the holding device comprises a frame, which surrounds one or more stents, and at least two support members being bearing mounted to the frame. The support members include a coil spring and a shaft to which the coil spring is connected. The coil spring has a first position of being engaged with the inner surface of the stent in which the stent is securely held at two opposing sides and can be rotated in relation to the frame. In a second position, the coil spring is disengaged from the stent and the coil spring can pass through the inner diameter of the stent to allow dismounting of the stent.
In one or more embodiments, the holding device may comprise one or more shafts which are bearing mounted to the frame to transmit rotary motion to one or more support members. Moreover, it may comprise sleeves being bearing mounted to the frame, wherein each support member is in contact with one sleeve and wherein in a first position, the support member is coupled to the sleeve to transmit rotary motion, and in a second position, the support member is uncoupled. Also, the holding device may include members, such as belts, to transmit rotary motion between the shaft and the support member. Furthermore, one or more guide sections may be provided.
In still another embodiment, an apparatus for applying linear and rotary motion to one or more stents is provided. The apparatus comprises a stent holding device including a frame which surrounds the stents, at least one shaft being rotably mounted to the frame and at least two support members being bearing mounted to the frame with two support members securing one stent at two opposing ends and one or more guide members. The holding device is in contact with one or more guide members and can be moved along the guide members to apply linear motion to the stents, and the stent can be rotated in relation to the holding device by applying rotary motion to at least one of the bearing mounted members.
In one or more embodiments, the apparatus may further comprise at least one inspection device, wherein the holding device can be moved along the guide members to allow positioning of the stents in relation to one or more inspection devices. In addition, at least one motion unit, such as a linear and rotary actuator, may be provided to transmit rotary and linear motion to the holding device in order to rotate and translate the stents.
In still another embodiment, a holding device for handling, securing and rotating one or more stents is provided, comprising a frame and at least one support member being bearing mounted to the frame and contacting at least a portion of the inner surface of the stent, wherein one support member is engaged with the stent at one end and the stent is securely held and can be rotated in relation to the frame.
In another embodiment, a method for securing and applying rotary motion to one or more stents is provided comprising the steps of locating two opposing support members in a first position, the support members being bearing mounted to the frame of a holding device surrounding the stent, and positioning a stent between the support members, locating the two support members at a second predetermined position in which the distance between the support members is smaller than the stent length to provide a repeatable securing of the stent, and transmitting rotary motion to at least one member which is bearing mounted to the holding device to rotate one or more stents in relation to the holding device.
In one or more embodiments, the method may comprise the step of applying a coating to one or more stents. It may also include the step of positioning the holding device so that one or more guide sections are in contact with one or more guide members. In addition, it may comprise the step of moving the holding device along the guide members to adjust the stent in relation to one or more inspection apparatus.
The accompanying drawings, which are incorporated in and constitute a part of this specification, serve to explain the principles of the invention. The drawings are in simplified form and not to precise scale.
The following figures illustrate embodiments of a holding device and a method to secure and rotate hollow cylindrical objects, such as stents.
As shown in
The position of the support members is determined by lock members 22, such as a pin or a securing ring, and by gears 7. In this embodiment, a pin is removably coupled to the support members to avoid axial displacement and to ensure a repeatable positioning of the support members in relation to the stent. To rotate the stent about its longitudinal axis within the frame structure, rotary motion may be transmitted from shaft 19 or from one of the support members 6 to the other support member via gears, which are provided at the support members and both ends of shaft.
The embodiment shown in
It is desirable to coat several stents simultaneously to allow higher volume production of medical devices.
With reference to
Alternatively, rotary motion can be transmitted from the motion unit to the support member and linear motion is transferred to the frame.
In a further alternative embodiment, each support member may be connected to a dedicated motion unit to transmit linear and/or rotary motion to the stent.
Motion unit 25, comprising guide member 24 on which the holding device 30 is removably mounted, is aligned via guide sections 21 in relation to guide member 24 and coupled to drive shaft 26. To easily connect or disconnect shaft 19 to drive shaft 26, the drive shaft may be equipped with an automated clamping mechanism. Linear and rotary motion is applied via drive shaft 26 to holding device 30. The motion is induced via shaft 19, belts 20, sleeves 29, which are magnetically coupled to stop member 34 and via support members 6 to the stents. The support members 6 are engaged with the stent at two opposing sides and the stent is securely held and can be rotated in relation to the frame. Adjustable stop members 34 are coupled to the sleeves 29 to secure the stent.
During the application of the coating, holding device 30 is moved in a linear direction relative to the two atomizers 27, which generate spray plume 28, and the stents are rotated. The two atomizers 27 are preferably aligned in relation to the stents, such that the center axis of the spray plume 28 is perpendicular to the rotation axis of stents 1 and both axes are located on the same plane.
After application of the coating, the holding device can be removed from drive shaft 26 and guide member 24.
For increased production output, the apparatus of
Another feature of the present invention is that the holding device can be furthermore used during subsequent inspection of the coated stents. An exemplary inspection setup is shown in
By using the holding device of the present invention it is not required to dismount and remount the stents for inspection purposes or to use inspection fixtures, which may damage the outer surface of the stent. Hence, coating damages during handling and inspection can be prevented or minimized resulting savings in time and cost.
Alternatively, the support members may be made from a folded sheet or may be constructed from a hollow profile, which can be polygon-shaped. They may also comprise passages having the shape of holes or slots. The support members can be made from a suitable metallic material such as stainless steel, titanium, cobalt chromium alloys or a suitable polymeric material such as Polyetheretherketone (PEEK).
In a first position shown in
A highly repeatable clamping mechanism is therefore provided which ensures that all supported stents are secured with an equal clamping force. High clamping forces, which can lead to a compressive and tensile load that may cause damage and deformation of the stent, can be therefore prevented.
The following method of precisely aligning and transmitting rotary and/or linear motion to one or more stents using the apparatus of the present invention is being provided by way of illustration and is not intended to limit the embodiments of the present invention.
Referring back to
To inspect the stent, stent holding device 30 may be placed with mounted stent 1 on inspection table 31, as shown in
The following example is being provided by way of illustration and is not intended to limit the embodiments of the present invention.
Stents (manufactured by STI, Israel) having a diameter of 2 mm and a length of 20 mm may be coated. The coating composition may include a solvent capable of dissolving the polymer at the concentration desired in the composition, a non-bioabsorbable or bioabsorbable polymer that can be dissolved in the composition, and a therapeutic substance. The composition can also include active agents, radiopaque elements, or radioactive isotopes.
The stents may be mounted on the holding device of the present invention as illustrated in
The holding device may move in a linear direction along the guide member in relation to the atomizers and may rotate both stents simultaneously at the same angular velocity. The two spray nozzles can disintegrate the coating solution into fine droplets at a liquid flow rate of about 0.1 to 80 ml/h and an atomizing pressure ranging from about 0.3 bar to about 1.5 bar. In order to achieve a fine atomization, the nozzles are preferably operated at an atomizing gas flow rate of 5 l/min at 0.8 bar atomizing pressure. For best results, the atomizer may be aligned in relation to the stent, such that the spray axis of the atomizer is perpendicular to the rotation axis of the stent and both axes are in the same plane. The spray nozzles are preferably positioned at a distance of approximately 12 to 35 mm from the nozzle tip to the outer surface of the stent. A syringe pump, which is operated at a constant flow rate, can be used to feed the coating substance to the atomizer. The flow rate of the coating solution may range from about 1 ml/h to 50 ml/h and is preferably 5 ml/h
During the application of the coating solution, rotary motion is transmitted from the drive shaft of the motion unit to the stents to rotate the stents about their central longitudinal axes. The rotation speed can be from about 5 rpm to about 250 rpm. By way of example, the stent may rotate at 130 rpm. The stents are translated along their central longitudinal axes along the atomizers. The translation speed of the stents can be from about 0.2 mm/s to 8 mm/s. When applying the coating solution, the translation speed is preferably 0.5 mm/s. The stents can be moved along the atomizer one time to apply the coating in one pass or several times to apply the coating in several passes. Alternatively, the atomizer may be moved one time or several times along the stent length.
Coating trials of several stents were performed using the holding device of the present invention.
While the invention will be described in connection with certain embodiments, it will be understood that the invention is not limited to these embodiments. On the contrary, the invention includes all alternatives, modifications and equivalents as may be included within the spirit and scope of the present invention. Details in the Specification and Drawings are provided to understand the inventive principles and embodiments described herein, to the extent that would be needed by one skilled in the art to implement those principles and embodiments in particular applications that are covered by the scope of the claims.
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7606625 *||Jun 15, 2007||Oct 20, 2009||Abbott Cardiovascular Systems Inc.||Method and device for aligning a stent with a stent support|
|US7853340 *||Sep 11, 2009||Dec 14, 2010||Abbott Cardiovascular Systems Inc.||Method for aligning a stent with a stent support|
|US7858143 *||May 7, 2007||Dec 28, 2010||Abbott Cardiovascular System Inc.||Apparatus and method for coating stents|
|US8003157||Jun 15, 2007||Aug 23, 2011||Abbott Cardiovascular Systems Inc.||System and method for coating a stent|
|US8055360 *||Oct 23, 2010||Nov 8, 2011||Abbott Cardiovascular Systems Inc.||Method and system for aligning a stent with a stent support|
|US8677650 *||Jun 15, 2007||Mar 25, 2014||Abbott Cardiovascular Systems Inc.||Methods and devices for drying coated stents|
|US9108205||Jun 18, 2009||Aug 18, 2015||Arzneimittel Gmbh Apotheker Vetter & Co. Ravensburg||Coating apparatus for coating an inside of a hollow body with an atomized fluid|
|US20110221113 *||Sep 29, 2009||Sep 15, 2011||Christoph Diederichs||Apparatus and method for processing a stent|
|WO2013055437A1 *||Aug 14, 2012||Apr 18, 2013||Abbott Cardiovascular Systems Inc.||Adjustable support for tubular medical device processing|
|U.S. Classification||427/2.24, 118/500, 427/240|
|International Classification||B05C13/00, B05D3/12, A61L33/00|
|Cooperative Classification||B05D1/002, A61F2/91, A61F2230/0054, B05B13/0228|
|European Classification||A61F2/91, B05D1/00C, B05B13/02B1|