Method for producing a coated medical support device

Method for producing a coated medical support device capable of insertion into the body, the method including the procedures of applying a coating to a section of a work-piece, positioning the work-piece in the vicinity of an electromagnetic field generator, and substantially proximate a forming mandrel, inducing electromagnetic forces in the work-piece which accelerate the work-piece toward the forming mandrel, and forming the work-piece to a medical support device, by changing the original physical configuration of the work-piece to a second physical configuration, the forming mandrel having a mandrel physical configuration, the second physical configuration being influenced by the mandrel physical configuration.

FIELD OF THE DISCLOSED TECHNIQUE

The disclosed technique relates to a method and apparatus for manufacturing medical devices, in general and to a method and apparatus for manufacturing medical support devices, in particular.

BACKGROUND OF THE DISCLOSED TECHNIQUE

Medical support devices are known in the art. An artery support device is also called a stent. Methods for manufacturing stents are known in the art. U.S. Pat. No. 5,767,480, to Anglin et al., is directed to a hole generation and lead forming for integrated circuit lead frames using laser machining.

U.S. Pat. No. 5,073,694 to Tessier et al., is directed to a method and apparatus for laser cutting a hollow metal work-piece. The method provides for the cutting of the hollow metal work-piece while minimizing or eliminating residue adherence to the inner circumference of the work-piece. Coolant is pumped through the apparatus to contact the inner portion of the work-piece before and during laser cutting.

U.S. Pat. No. 5,345,057 to Muller, is directed to a method of cutting an aperture in a device by-means of a laser beam.

U.S. Pat. No. 5,780,807 to Saunders, is directed to a method and apparatus for direct laser cutting of metal stents. The expandable stent is made from a single length of tubing and utilizes direct laser cutting from a single metal tube using a finely focused laser beam. The stent may be made in a variety of ways, but the preferred method provides for cutting a thin-walled tubular member of materials such as stainless steel in order to remove portions of the tubing and give a desired pattern. This is done by utilizing a laser beam.

U.S. Pat. No. 5,707,385 to Williams, is directed to a drug loaded elastic membrane comprising an expandable sheath for delivering a therapeutic drug in a body lumen. The expandable membrane has a first layer and a second layer, which are joined along their edges to form a fluid-tight seal. Before joining the layers, a plurality of apertures are formed in the first layer by known methods such as using a laser.

U.S. Pat. No. 5,843,117 to Alt et al., is directed to an implantable vascular and endoluminal stent and the process of fabricating the same. Tube-type stent is fabricated from tubing with longitudinally oriented struts coupled together by bars or bridges, which define a plurality of through-holes in the wall of the tube. This multiplicity of through-holes is cut by a laser beam.

U.S. Pat. No. 5,531,741 to Barbacci, is directed to illuminated stents which are designed as an improved light emitting device. The stent is formed by extruding a length of tubing and then followed by molding and shaping. Drainage openings are formed in one step of the process. These holes may be made by piercing the wall of the tubing by utilizing a sharpened cutter or by use of a laser.

Electromagnetic forming (EMF) is known in the art. In general, this method is used to form, cut, pierce, and join metals having relatively high electrical conductivity, such as copper, mild alloy, aluminum, low-carbon steel, brass, and molybdenum. The EMF process uses a capacitor bank, a forming coil, a field shaper (mandrel), and an electrically conductive work-piece to create intense magnetic fields that are used to do useful work. This intense magnetic field, produced by the discharge of a bank of capacitors into a forming coil, lasts only a few microseconds. The resulting eddy currents that are induced in a conductive work-piece that is placed close to the coil, then interact with the magnetic field to cause mutual repulsion between the work-piece and the forming coil. The force of this repulsion is sufficient to stress the work metal beyond its yield strength, resulting in a permanent deformation. The magnetic field rapidly accelerates the work-piece against the mandrel, thus forming it to the desired shape. Because the actual forming takes place in a matter of a few microseconds, the high strain rate forming does not affect the material properties in an adverse way. The pressure induced on the work-piece, is comparable to that encountered in mechanical forming of similar parts.

EMF can be usually applied to five forming methods: compression, expansion, contour forming, punching and joining. It is used to expand, compress, or form tubular shapes, to form a flat sheet, and to combine several forming and assembly operations into a single step. It is used in single-step assembly of metal parts to each other or to other components, such as in electrical cables, and joining of aluminum and copper. Highly resistant metals such as titanium, need special EMF equipment, which operate at higher frequencies in the range of 20 to 100 kHz.

Because the material is loaded into its plastic region, the springback often associated with mechanical forming, is virtually absent in electroformed parts. Joints made by EMF process are typically stronger than the parent material, and compared to other joining methods, such as laser welding. Assemblies using metal parts formed onto plastics, composites, rubber, and ceramics are also common.

U.S. Pat. No. 6,153,252 issued to Hossainy et al., and entitled “Process for Coating Stents” is directed to a method for coating stents in order to prevent the formation of bridges. The stent is placed over a mandrel whose outer diameter is less than the inner diameter of the stent. The stent and the mandrel are dipped into the coating solution. The stent and the mandrel are removed from the coating solution and the coated stent is moved relative to the mandrel. The relative outer diameter of the mandrel and the inner diameter of the stent is such that while the coating is still wet, the movement of the stent along the length of the mandrel, clears the passages of the stent, which remain open after drying.

U.S. Pat. No. 5,534,287 issued to Lukic and entitled “Methods for Applying an Elastic Coating Layer on Stents”, is directed to methods for applying a covering layer to an expandable stent, the expandable stent having a discontinuous wall. The covering layer is an elastomeric polymerizable composition. The expandable stent which is in form of a wire mesh, is radially contracted. The inner surface of a tube is coated with a lifting medium, in order to prevent adherence to the covering layer. The expandable stent is inserted into the tube and the expandable stent is allowed to radially expand.

The assembly of the tube and the expandable stent is wetted in the elastomeric polymerizable composition, dissolved in a sufficient amount of solvent, to permit wet forming of a continuous covering layer around the expandable stent. The solvent is evaporated, the elastomeric polymerizable composition is polymerized in the tube and the stent which is covered with the covering layer, is removed from the tube.

SUMMARY OF THE DISCLOSED TECHNIQUE

It is an object of the disclosed technique to provide a novel coated medical support device capable of insertion into the body, and a method for producing the same, which overcome the disadvantages of the prior art. The method includes the procedures of applying a coating to a section of a work-piece, positioning the work-piece in the vicinity of an electromagnetic field generator, and substantially proximate a forming mandrel. The method further includes the procedure of inducing electromagnetic forces in the work-piece which accelerate the work-piece toward the forming mandrel. The method further includes the procedure of forming the work-piece to a medical support device, by changing the original physical configuration of the work-piece to a second physical configuration, wherein the second physical configuration is influenced by a mandrel physical configuration of the forming mandrel.

In accordance with another aspect of the disclosed technique, there is thus provided a medical support device capable of insertion into the body. The medical support device includes an electromagnetically formed work-piece and a coating, which coats at least a section of the work-piece.

The work-piece is formed into a medical support device shape by positioning the work-piece in the vicinity of an electromagnetic field substantially proximate a forming mandrel. The work-piece is further formed by inducing electromagnetic forces in the work-piece and by changing the physical configuration of the work-piece according to the forming mandrel.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The disclosed technique overcomes the disadvantages of the prior art by providing a novel method for manufacturing medical support devices and elements, using electromagnetic forming (EMF) techniques.

Reference is now made toFIG. 1, which is a schematic illustration of a system for manufacturing metal medical support elements, generally referenced100, constructed and operative in accordance with an embodiment of the disclosed technique.

System100includes a forming coil106(electromagnetic generators), energy storage capacitors104and a power supply102. The energy storage capacitors104are coupled with the power supply102and with the forming coil—the electromagnetic field generator106. In the present example, the electromagnetic field generator includes a metal coil.

The forming coil106is placed around a conductive metal object, generally referenced110and forming coil106produces pulses of electromagnetic field. A field shaper mandrel112is inserted between the work piece110and the coil106. The electromagnetic generator (forming coil106) produces pulses of electromagnetic field. This very intense electromagnetic field is produced by the discharge of a bank of capacitors104into the forming coil106. The resulting eddy currents that are induced in the conductive metal object, then interact with the magnetic field to cause mutual repulsion between the conductive metal work-piece110and the forming coil106. The force of this repulsion is sufficient to stress the metal work-piece beyond its yield strength, resulting in a permanent deformation.

The field shaper mandrel112is used to concentrate the magnetic field at the points at which the forming/cutting is desired. The magnetic pressure is localized in certain regions of the metal work-piece. This technique most efficiently uses stored energy to produce high local forming pressures in desired areas. In the present example, mandrel112includes a hole. Accordingly, apparatus100can Electro-Magnetically “punch” a hole in work-piece110, by accelerating metal work-piece110toward the hole bearing mandrel112.

Reference is now made toFIG. 2, which is an illustration of two wires to be joined together and a forming coil, constructed and operative in accordance with another embodiment of the disclosed technique. Wires162and160are placed one over the other, whereby they cross each other at a crossing section164. A support member166is placed underneath wire160. An accelerator element168can be placed over the crossing section164. A forming coil152is located around the crossing section164and the support member166. At a predetermined moment, the forming coil152produces a magnetic field pulse. This electromagnetic field accelerates the two wires, toward the support member166, thereby forcing them to join at the crossing section164. At the same time, the magnetic field pulse also accelerates the accelerator element168toward the support member166. Accelerator element168can be used in various cases where additional forces are required, such as, when the two joined pieces are characterized by poor conductivity or non at all.

It is noted that the material characteristics of the two wires162and160are not changed outside the crossing section164. The strength of the welded joint is at least comparable to the strength of the parent material.

Reference is now made toFIG. 3A, which is a cross sectional illustration of a stent manufacturing device, generally referenced200, constructed and operative in accordance with a further embodiment of the disclosed technique. Device200includes a mandrel204and a coil202. Mandrel204is a general hollow tube (defined by a shaft208), which includes a plurality of holes206, at the perimeter thereof. Mandrel204is concentrically placed within coil202. A tubular work-piece210is concentrically placed between mandrel204and coil202.

Reference is further made toFIG. 3B, which is a cross sectional view of device200and work-piece210ofFIG. 3A. Coil202produces an electromagnetic pulse, when an electrical current pulse is conducted there through. This magnetic pulse causes a counter flow of electrical current within the work-piece210. The vector combination of the electromagnetic field and the counter electric current, causes the generation of mechanical forces on the work-piece210, which are directed toward the center of mandrel204.

As a result, pieces (generally referenced214) of material of the work-piece210are sheared against openings206, thus producing holes212. In accordance with one aspect of the disclosed technique, the various portions of the work-piece210can be punched in a single cycle. Alternatively, the entire work-piece210can be punched in a single cycle. It is noted that the material characteristics of the work-piece210are substantially maintained throughout and after the punching process. The amount of heat, generated through the process of the disclosed technique is significantly reduced with comparison to other method for manufacturing stents from a single work-piece.

Reference is now made toFIGS. 4A,4B,4C and4D.FIG. 4Ais a side view illustration of a work-piece, generally referenced310, and a device, generally referenced300, for executing a preliminary stage in the manufacturing of a tubular device, constructed and operative in accordance with another embodiment of the disclosed technique.FIG. 4Bis an illustration in perspective of the coil of the device ofFIG. 4A.FIG. 4Cis an illustration in perspective of the mandrel of the device ofFIG. 4A.FIG. 4Dis an illustration in perspective of the work-piece ofFIG. 4A.

Device300includes a coil302and a mandrel304. Coil302is a flat coil, which is adapted to surround flat objects (FIG. 4B). Mandrel304(FIG. 4C) is a flat surface, which includes a plurality of holes, generally referenced308. Mandrel304is placed within coil302(FIG. 4A). Work-piece310is placed within coil302, adjacent to mandrel304. When coil302conducts a strong electric pulse, it produces a respective magnetic field pulse, therein. The magnetic field induces electrical current in the work-piece310, and in turn causes mechanical forces, which drive the work-piece310toward mandrel304. These forces are significantly strong and press the work-piece310against mandrel304. In the present example, these forces cause shearing of work-piece material, where the mandrel304exhibits a sharp edge, such as in holes308.

Reference is further made toFIG. 4E, which is an illustration in perspective of work-piece310, after being treated by device300. Now, work-piece310includes holes, generally referenced312, in a pattern, which is respective of the hole pattern of mandrel304. The above device and procedure, provide means for perforating a pattern of holes in a material sheet, which can be further folded, and formed to a shape of a perforated tube. The edges of the material sheet may be joined by metal joining methods known in the art, such as arc welding, gas welding, resistance welding, soldering, brazing, electron beam welding, laser beam welding, friction welding, diffusion bonding, explosive welding, ultrasonic welding, adhesive bonding, EMF forming, and the like.

It is noted that if an accelerating element (as described herein below in connection withFIG. 6) is employed, work-piece310can be made of a non-conductive material. Thus, work-piece310can be made of a shape memory material, super elastic material as well as stainless steel, alloy, polymeric material, biocompatible material, and the like.

Reference is now made toFIG. 5, which is an illustration in perspective of a forming device, generally referenced350, constructed and operative in accordance with a further embodiment of the disclosed technique. Device350includes a coil352and a mandrel354. Mandrel354is a massive support device, which is fixed to its place. A work-piece360made of a generally flat sheet of material, is folded to form a tubular object. Device350is designed to firmly couple the overlapping edges362and364of work-piece360, thereby producing a closed shape.

Work-piece360is inserted in coil352. Mandrel354is inserted inside work-piece360, and placed in the vicinity of overlapping edges362and364. As a strong pulse of electric current flows through the wire, which includes coil352, the coil352produces a strong magnetic field pulse. This magnetic pulse, causes a counter electric current pulse in work-piece360. The vector combination of the magnetic pulse and the counter electric current pulse, produce a mechanical force, which accelerates overlapping edges362and364toward mandrel354. The strong impact force, causes the two overlapping edges362and364to join together, thereby producing a closed cylinder.

It is noted that this procedure can be performed on work-pieces, which were treated according to the procedure presented above, in conjunction withFIG. 4A. Alternatively, this procedure can be used independently, for work-pieces, which were initially treated by any other forming technique known in the art. Such techniques include laser beam machining, electrical discharge machining, electrochemical machining, chemical machining, photochemical blanking, abrasive jet machining, abrasive flow machining, ultrasonic machining, hydrodynamic machining, electronic beam machining, stamping, fine blanking, drilling, and the like.

It is noted that the disclosed technique can also be implemented for forming materials, which exhibit poor electrical conductivity or non at all, by utilizing an accelerator element. The accelerator element is made of a highly electrical conductive material, which provides high-induced currents.

Reference is now made toFIG. 6, which is a cross-sectional illustration of a forming device, generally referenced370, constructed and operative in accordance with another embodiment of the disclosed technique. Device370includes a coil372, a mandrel374and an accelerating element376. Two work-pieces380and382are inserted in coil372, overlapping each other.

Reference is now made toFIGS. 7A and 7B.FIG. 7Ais a cross-sectional illustration of a forming device, generally referenced400, constructed and operative in accordance with a further embodiment of the disclosed technique.FIG. 7Bis an illustration in perspective of a coil of the device ofFIG. 7A. Device400includes a pair of coils402A and402B and a mandrel404. Coils402A and402B each is designed and constructed in the form of a ring.

The coils402A and402B are positioned parallel to each other. Mandrel404is placed between the coils402A and402B. A work-piece410is placed between coil402A and mandrel404, in close vicinity to coil402A. When wire408conducts an electric current pulse, it produces in turn, a magnetic field pulse, which is induced onto work-piece410. Work-piece410produces a counter electric current. The vector combination of the magnetic field and the counter electric current pulse produces a mechanical force, which accelerates work-piece410toward mandrel404. Work-piece410is deformed depending on the shape (curves and openings) which characterizes mandrel404.

Reference is further made toFIG. 7C, which is a cross-sectional illustration of a forming device, generally referenced420, constructed and operative in accordance with another embodiment of the disclosed technique. Forming device420includes a coil422similar to coil402A as described with reference toFIG. 7A, and a mandrel426. A work-piece424is placed between the coil422and mandrel426. Work-piece424is deformed depending on the shape (curves and openings) which characterizes mandrel426, in a process similar to that described with reference toFIG. 7A.

Reference is now made toFIG. 8, which is a schematic illustration of a metal web, generally referenced450, constructed in accordance with a further embodiment of the disclosed technique. Web450is formed from a plurality of wires, generally referenced452and454. These wires are arranged in a crosswise structure, wherein the length portion is made of wires452, and the breadth portion is made of wires454. An intersection between a selected length wire452and a selected breadth wire454is denoted456. In the present example, the upper right intersection456is further denoted by a circle. In accordance with the disclosed technique, each of these intersections, is joined using electromagnetic forming techniques. It is noted that each of the wires452and454can be made using a different metal or conductive compound material.

For example, the length portion wires can be made of elastic alloys while the breadth portion wires are made of shape memory alloys. It is noted that the use of electromagnetic forming, simplifies the manufacturing process, while maintaining the original characteristics of the materials used, such as elasticity, plasticity, shape memory characteristics, and the like.

Reference is now made toFIG. 9A, which is a schematic illustration of a plurality of wire elements, generally referenced470, and a wire structure, constructed and operative in accordance with another embodiment of the disclosed technique. Wire470is shaped, generally as a uniform sinus waveform. Wires470A,470B and470C, being identical to wire470, form a mesh structure, when placed side by side and joined at selected intersections (generally referenced472) thereof, by means of electromagnetic forming techniques.

It is noted that similarly to the structure ofFIG. 8, various types of material can be used to form each of the wires470. Hence, the structure can be made of many different materials. In the present example, wire470A is made of shape memory material having a two-way action, at two different temperatures, wire470B is made of shape memory alloy having a one way action, at a predetermined temperature and wire470C is made of a spring alloy. It is noted that alloys having plastic characteristics can also be used for such wires.

Reference is now made toFIGS. 9B and 9C.FIG. 9Bis an illustration of a wire, generally referenced500, constructed in accordance with a further embodiment of the disclosed technique.FIG. 9Cis an illustration of a mesh structure, generally referenced510, constructed in accordance with another embodiment of the disclosed technique.

Wire500is shaped as a non-uniform wave function, having “maximum” locations, generally referenced502and504. It is noted that in accordance with further aspects of the disclosed technique, this wave function can include a combination of any known wave function, such as triangle, square, chainsaw, and the like. With reference toFIG. 9C, a plurality of wires500are joined together by means of electromagnetic technique, to form mesh structure510.

Reference is further made toFIG. 9D, which is an illustration of a medical support device, generally referenced520, constructed and operative in accordance with a further embodiment of the disclosed technique. In general, each of the mesh or web structures presented above, can be used to form a medical support device such as a stent or a catheter tip. In the present example, mesh510(FIG. 9C) is curved so that the left side meets the right side thereof, thereby forming support device520. It is noted that the intersections between a left side wire500A and a right side wire500B can be fixed together by means of electromagnetic forming techniques, where one electromagnetic coil is placed around the tube mesh, or by any other joining technique, such as laser welding.

Reference is now made toFIGS. 10A,10B, and10C.FIG. 10Ais an illustration in perspective of a forming device, generally referenced550, constructed and operative in accordance with another embodiment of the disclosed technique.FIG. 10Bis an illustration in perspective of a mandrel, generally referenced554A, for use with the forming device550ofFIG. 10A, constructed in accordance with a further embodiment of the disclosed technique.FIG. 10Cis a side view of forming device550ofFIG. 10A.

Forming device550includes a forming coil552, a mandrel554and a conductive layer556. Mandrel554is adapted to receive a plurality of wires, arrange them in a predetermined structure and hold them together during the forming procedure. With reference toFIG. 10B, mandrel554A includes a plurality of groves, generally referenced558A, which define a web like structure. These grooves are then filled with wires and formed within device550.

Referring both toFIGS. 10A and 10C, a plurality of wires, generally referenced560are placed in grooves558. Mandrel554and the inserted wires560are wrapped with conductive layer556, which increases the conductivity of the wire structure. Similar to devices presented herein above, the coil552produces a magnetic field pulse as an electric current pulse flows there through. In turn, the combination of conductive layer556and wires560produce a counter electric current and the combination of the above produces a mechanical force, which bonds the wires together.

In accordance with another aspect of the disclosed technique, a coating is applied to the work-piece and a coated stent is constructed, by forming the coated work-piece with the aid of an electromagnetic field generator. Electromagnetic forming operation does not change any of the properties of the coating, nor does it expose the work-piece to high temperatures. Accordingly, the work-piece can be coated with a variety of coatings, with great ease, before it is formed into a stent. Hence, different types of coatings of different thicknesses can be applied to hard-to-reach surfaces of the stent (e.g., inner surfaces), while substantially eliminating the formation of bridges (i.e., perforations plugged by the coating).

Reference is now made toFIGS. 11A,11B, and11C.FIG. 11Ais an illustration in perspective of a coated work-piece, generally referenced580.FIG. 11Bis an illustration in perspective of a system for forming a plurality of perforations in the coated work-piece ofFIG. 11A, generally referenced590, constructed and operative in accordance with another embodiment of the disclosed technique.FIG. 11Cis an illustration in perspective of the coated work-piece ofFIG. 11A, after being formed by the system ofFIG. 11B.

Coating584can further be made of a substantially flexible material or, (e.g., gold, complex—titanium nitride oxide or as described above), such that work-piece582remains flexible even after applying coating584to work-piece582. When such a coating is applied to a stent, it is possible to deform the coated stent (e.g., expanding, contracting, twisting, bending, compressing and extending).

Coating584can be applied to work-piece582, by methods known in the art, such as by dipping work-piece582in a liquid bath, by spraying work-piece582(i.e., printing with an inkjet, bubble-jet, and the like), by electrolysis, and the like. Thus, either one side or both sides of the work-piece can be coated with the coating. Moreover, the thickness of coating584on work-piece582can be controlled in a manner which is particular to the respective method of coating.

With reference toFIG. 11B, system590includes two forming coils592and594similar to forming coils106(FIG. 1), coupled with energy storage capacitors (not shown), similar to energy storage capacitors104and with a power supply586, similar to power supply102. Coated work-piece580is placed between coils592and594, and a mandrel596similar to mandrel304(FIG. 4C), is placed between coil592and coated work-piece580. Mandrel596includes a plurality of holes598.

When an electromagnetic field is generated by coils592and594, selected regions of coated work-piece580in the vicinity of holes598yield, thereby forming a plurality of holes600in coated work-piece580(FIG. 11C). It is noted that holes600are formed in work-piece582as well as in coating584. The operation of coils592and594is of short duration, substantially no heat is generated during this operation and substantially no mechanical strain is applied to coating584. Therefore, the physical properties (e.g., thickness) and chemical properties (e.g., molecular structure) of coating584remain substantially constant throughout the forming operation.

It is noted that the coated work-piece can be rolled to a cylinder similar to tubular object360(FIG. 5). Then, the two edges of the cylinder can be joined together by employing a forming device similar to forming device350, thereby constructing a coated tubular object.

Reference is now made toFIGS. 12A,12B, and12C.FIG. 12Ais an illustration in perspective of a cross section of a coated tubular work-piece, generally referenced620.FIG. 12Bis an illustration in perspective of a cross section of a system for forming a plurality of perforations in the coated tubular work-piece ofFIG. 12A, generally referenced640, constructed and operative in accordance with a further embodiment of the disclosed technique.FIG. 12Cis an illustration in perspective of a cross section of a coated stent, generally referenced650, formed from the coated tubular work-piece ofFIG. 12A, by the system ofFIG. 12B, in accordance with another embodiment of the disclosed technique.

Coated tubular work-piece620includes a tubular work-piece622and coatings624and626. Coating624is applied to an outer surface (not shown) of tubular work-piece622and coating626is applied to an inner surface (not shown) of tubular work-piece622. Coatings624and626can be either the same or different. For example, coating624is a substance which prevents intimal proliferation (i.e., restenosis) and coating626is a substance which prevents thrombosis (i.e., clotting). The thicknesses of coatings624and626can be either substantially the same or different.

With reference toFIG. 12B, system640includes a coil642and a mandrel644. Coil642and mandrel644are similar to coil202(FIG. 3A) and mandrel204, respectively. Mandrel644includes a plurality of holes646. The outer diameter (not shown) of mandrel644is smaller than the inner diameter (not shown) of coated tubular work-piece620. Coated tubular work-piece620is placed within coil642and mandrel644is placed within coated tubular work-piece620.

When an electromagnetic field is generated by coil642, selected regions of coated tubular work-piece620in the vicinity of holes646yield, thereby forming a plurality of holes648(FIG. 12C) in coated tubular work-piece620and forming coated tubular work-piece620into a coated stent650. It is noted that holes648are made in tubular work-piece622, as well as in coatings624and626. Thus, when coated stent650is placed inside a lumen of a patient, coatings624and626gradually dislodge from the outer surface and the inner surface of coated650, respectively, and are absorbed by the tissue of the patient or the bodily fluids thereof.

Reference is now made toFIG. 13, which is an illustration in perspective of a coated stent, generally referenced670, constructed and operative in accordance with a further embodiment of the disclosed technique. Coated stent670includes a plurality of coatings672,674and676on the outer surface (not shown) thereof and a plurality of holes678.

Coatings672,674and676as well as the thicknesses thereof, are different. Thus, when coated stent670is placed within the lumen of the patient, a prescribed dose of each of the substances of coatings672,674and676is absorbed by the tissue or the bodily fluid of the patient. Alternatively, the inside surface (not shown) of the coated stent can be coated with different coatings at different thicknesses.

Reference is now made toFIG. 14, which is a schematic illustration of a cross section of a multiply-coated medical support device, generally referenced700, constructed and operative in accordance with another embodiment of the disclosed technique. Multiply-coated medical support device700includes a plurality of coatings702,704and706, which are overlaid one on top of the other. Coatings702,704and706are different. The thickness of coatings702,704and706can be either the same or different. Coatings702,704and706are applied on the outer surface of multiply-coated medical support device700. However, other coatings (not shown) can be applied also to the inner surface of the multiply-coated medical support device.

Reference is now made toFIG. 15, which is a schematic illustration of a method for constructing a coated medical support device, operative in accordance with a further embodiment of the disclosed technique. In procedure710, at least one coating is applied to at least one section of a work-piece, the work-piece having an original configuration. With reference toFIG. 11A, work-piece582is coated with coating584, at a predetermined thickness, on a surface of work-piece582. At this stage of the construction method, work-piece582is free of any holes (i.e., having the original configuration). Alternatively, different sections of the surface of work-piece582can be coated with different types of coatings at different thicknesses. Further alternatively, different sections of the other side of the work-piece can be coated with other coatings at different thicknesses.

In procedure712, the work-piece is positioned in the vicinity of an electromagnetic field generator, and substantially proximate a forming mandrel, the forming mandrel having a mandrel physical configuration. With reference toFIG. 11B, coated work-piece580is positioned between forming coils592and594and mandrel596is positioned between forming coil592and coated work-piece580. Mandrel596is provided with a plurality of holes598(i.e., having mandrel physical configuration). Forming coils592and594, power source586and the energy storage capacitors form an electromagnetic field generator.

In procedure714, electromagnetic forces are induced in the work-piece, which accelerate the work-piece toward the forming mandrel. With reference toFIG. 11B, the electromagnetic field generator (i.e., forming coils592and594, the energy storage capacitors and power source586), induce electromagnetic forces in coated work-piece580, which in turn accelerate coated work-piece580toward mandrel596.

In procedure716, the work-piece is formed to a medical support device, by changing the original physical configuration to a second physical configuration, the second physical configuration being influenced by the mandrel physical configuration. With reference toFIG. 11C, the acceleration of coated work-piece580toward mandrel596, causes a plurality of holes600, substantially similar to holes598, to be formed in coated work-piece580. In this manner the physical configuration of coated work-piece580as inFIG. 11A(i.e., the original configuration), is changed to that ofFIG. 11C(i.e., the second configuration).

It is noted that the second physical configuration of coated work-piece580is influenced by the physical configuration of mandrel596. It is further noted that procedure710can be performed after procedure716(i.e., the work-piece is first formed and then coated).

It will be appreciated by persons skilled in the art that the disclosed technique is not limited to what has been particularly shown and described here in above. Rather the scope of the disclosed technique is defined only by the claims which follow.