Medical devices formed with microcoatings to form functionally graded materials and methods of manufacture

Abstract

A method of making a stent includes using a micro-coating to form a precursor stent. The precursor stent includes a plurality of bands made of a first material configured adjacent to each other and a plurality of connections connecting each band to an adjacent band. The precursor stent includes a plurality of first connections configured to remain and a plurality of second connections made by functionally grading the first material with a second material to create embrittlement. The plurality of second connections are configured to be removed. The precursor stent is processed to remove the plurality of second connections without adversely affecting the bands and the plurality of first connections. The second material can be a radiopaque material.

Description

Technical Field

[0001] This invention relates generally to methods of manufacturing medical devices, and more specifically to a method of manufacturing a scaffold using a microcoating manufacturing process to form a functionally graded material. Background Technology

[0002] There are a wide range of medical approaches that use medical devices, including stents or intracavitary prostheses. As used herein, the term “stent” is intended to refer to a medical device suitable for temporary or permanent implantation in body cavities, including both naturally occurring and artificially constructed cavities, such as, but not limited to: arteries, whether or not located in the coronary, mesenteric, peripheral, or cerebrovascular systems; veins; the gastrointestinal tract; the biliary tract; the urethra; the trachea; hepatic shunts; and the fallopian tubes.

[0003] Therefore, different scaffolds have been developed, each providing a unique and beneficial structure to modify the mechanical properties of the target cavity wall. For example, scaffold prostheses are known for implantation within body cavities to provide artificial radial support to the wall tissues that form various cavities within the human body.

[0004] Several methods exist for fabricating stents, including corrugating wires into a wave and spirally winding them around a mandrel, removing material from a tubular cylinder using a laser to leave a stent (sometimes called a slotted tubular stent or laser-cut stent), and forming individual cylindrical components and attaching adjacent cylindrical components to each other to form a tube. Such methods can be labor-intensive, expensive, and time-consuming. Additive manufacturing techniques will be expected to be used to manufacture stents and other medical devices. However, additive manufacturing techniques may be limited in manufacturing certain shapes of medical devices, particularly stents of certain shapes. For example, and not limitingly, certain generally tubular medical devices, such as stents, can be formed by additive manufacturing that constructs the medical device vertically. In other words, the longitudinal axis of the medical device is perpendicular to the surface or substrate on which the medical device is constructed. In additive manufacturing, layers, also known as medical device material coatings, are built on top of previous layers of material. In some medical devices, such as certain stents, it is desirable that a large portion of the perimeter of the first part of the device is not connected to the second part of the device. For example, but not limited to, in a support having multiple bands formed by struts and crowns, it is generally desirable to connect only some of the crowns of the bands to the crowns of adjacent bands. However, when such a support is constructed vertically by additive manufacturing as described above, it is desirable to construct connections between most or all of the crowns of adjacent bands to provide support for subsequent layers of material.

[0005] In the solution described in U.S. Patent No. 9,114,032, assigned to Medtronic Vascular, Inc., the connectors are formed between the crowns of the stent by additive manufacturing, the entire contents of which are incorporated herein by reference. However, some of the connectors are subsequently removed by laser removal, chemical etching, or other methods. Removing the connectors after their formation requires additional steps and must be done carefully to avoid adversely affecting the remaining stent components during the removal of unwanted connectors.

[0006] Furthermore, medical devices such as stents are made of a variety of alloy materials, such as, but not limited to, cobalt-chromium alloys or stainless steel. These alloys provide the stent with desired properties, such as flexibility and rigidity. However, the density of these alloys is insufficient to be seen during interventional procedures using existing imaging methods such as fluorescence imaging. To increase the radiopaque linearity of the stent, and in an additional manufacturing step, typically after the stent is manufactured, a radiopaque material is welded to the stent.

[0007] Therefore, it is desirable to construct medical devices such as stents using additive manufacturing processes, wherein there are connections between the various parts of the medical device, which can be removed more easily, effectively, and efficiently without adversely affecting the remaining parts of the medical device. It will also be desirable to achieve higher radiopaque linearity for certain parts of the medical device in the same process. Summary of the Invention

[0008] The embodiments described herein relate to methods of manufacturing medical devices using microcoatings. The method includes forming a precursor medical device comprising a plurality of strips made of a first material arranged adjacent to each other, wherein each strip is attached to the adjacent strips by a plurality of first connectors configured to remain and a plurality of second connectors configured to be removed. The plurality of second connectors are formed by functionally grading the first material with a second material to induce embrittlement in the plurality of second connectors. The method also includes processing the precursor medical device to remove the plurality of second connectors without adversely affecting the strips and the plurality of first connectors.

[0009] The embodiments herein also relate to a method of forming a medical device having a radiopaque portion. The precursor medical device includes forming the precursor medical device using a microcoating, wherein the precursor medical device includes a plurality of strips made of a first material arranged adjacent to each other, wherein each strip is attached to adjacent strips by a plurality of first connectors configured to remain and a plurality of second connectors configured to be removed. By functionally grading the first material with a second radiopaque material, at least a portion of at least one of the plurality of strips and / or at least one of the plurality of first connectors is radiopaque. The method further includes processing the precursor medical device to remove the plurality of second connectors without adversely affecting the strips and the plurality of first connectors.

[0010] Embodiments herein also relate to a prodrug comprising a plurality of portions or strips made of a first material configured adjacent to each other, a plurality of first connecting portions connecting each strip to adjacent strips, and a plurality of second connecting portions connecting each strip to adjacent strips. The plurality of first connecting portions are configured to remain, and the plurality of second connecting portions are made by functionally grading the first material and the second material to produce embrittlement, such that the plurality of second connecting portions are configured to be removed.

[0011] Embodiments herein also relate to a medical device comprising a plurality of portions or strips made of a first material configured adjacent to each other and at least one connecting portion connecting each strip to an adjacent strip. The at least one connecting portion is made by functionally grading the first material with a radiopaque second material. Attached Figure Description

[0012] The foregoing and other features and advantages of the invention will become apparent from the following description of embodiments of the invention illustrated in the accompanying drawings. The drawings, which are incorporated herein and constitute a part of this specification, also serve to illustrate the principles of the invention so that those skilled in the art can make and use it. The drawings are not drawn to scale.

[0013] Figure 1 This is a flowchart illustrating the steps of a method for manufacturing a medical device according to an embodiment of the present invention.

[0014] Figure 2 It is applicable Figure 1 A schematic diagram of an embodiment of the microcoating system of the method.

[0015] Figure 3 Is Figure 1 A schematic side view of an embodiment of the precursor support manufactured in the steps of the method.

[0016] Figure 4 It is shown Figure 3 A diagram illustrating an example of a mutational functional grading pattern in the second connector of the precursor scaffold.

[0017] Figure 5 It is shown Figure 3 A diagram showing another example of the functional hierarchical style of the second connection of the precursor support.

[0018] Figure 6 It is shown Figure 5 A diagram of the phase diagram of a system with functional hierarchical style.

[0019] Figure 7 It is shown Figure 3 A diagram illustrating an example of the functional hierarchical style of the first connector of the precursor support.

[0020] Figure 8 It is shown Figure 3 A diagram illustrating an example of the functional grading pattern of the struts of the precursor support.

[0021] Figure 9 yes Figure 3 A schematic diagram of a flattened two-dimensional representation of a portion of the precursor support band.

[0022] Figure 10 It is shown Figure 3 The figure shows another example of the functional hierarchical style of the first connection and / or strut of the precursor support.

[0023] Figure 11 Is using Figure 1-10 A schematic side view of an embodiment of a precursor support manufactured by the method.

[0024] Figure 12 Is Figure 11 The area obtained at "A" Figure 11 A close-up schematic diagram of an embodiment of the first connection between the crowns of adjacent bands of the support.

[0025] Figure 13 Is Figure 11 The "B" region obtained Figure 11 A close-up schematic diagram of an embodiment showing the gap between the crowns of adjacent bands of the support. Detailed Implementation

[0026] Specific embodiments of the invention are now described with reference to the accompanying drawings, wherein similar reference numerals indicate the same or functionally similar elements.

[0027] Figure 1 This is a flowchart illustrating an embodiment of a method 100 for forming a medical device according to an embodiment of the present invention. (Refer to...) Figure 1The described method is a way to manufacture medical devices using laser microcoatings, commonly referred to as microcoatings. Microcoating is a type of laser metal deposition (LMD) additive manufacturing process. The term "microcoating," also commonly referred to as "additive manufacturing," "3D printing," or "rapid prototyping," refers to the process of creating a three-dimensional entity of virtually any shape based on a digital model. Microcoatings are achieved through additive manufacturing processes in which continuous layers of material are laid up in different shapes. As used herein, the terminology may refer to methods including, but not limited to, laser metal deposition (LMD), laser cladding, and laser microcladding. Furthermore, any type of additive manufacturing machine can be used to lay up or coat the materials described herein.

[0028] Generally, microcoatings manufacture parts by adding material rather than removing it. Laser additive manufacturing (LAM) is a process that uses lasers to bond materials to create structures. LAM is typically performed sequentially, layer by layer, using information contained in a 3D CAD file. LAM is generally divided into two categories: selective laser melting (SLM) or laser metal deposition (LMD). Laser metal deposition (LMD), also known as laser cladding, uses a high-power energy beam, such as a laser, to project molten metal powder in flight and deposit it onto a substrate. The metal powder, the necessary protective gas, and the energy beam can be delivered simultaneously, forming a molten pool on the substrate (working surface). Laser metal deposition (LMD) ultimately creates a complete metallurgical bond between the laminated or cladding material and the existing substrate. Laser microcoating is a subcategory of laser cladding and refers to the process described above for manufacturing miniaturized structures and components, such as certain types of medical devices.

[0029] therefore, Figure 2 A simplified exemplary embodiment of a microcoating system 200 suitable for the purposes described herein is shown. Figure 2The microcoating system 200 includes a first powder delivery system 202, a second powder delivery system 204, a substrate 220, and an energy source or laser 208. The first powder delivery system 202 includes a first hopper 211, a first feed tube 213, and a first nozzle 212. The second powder delivery system 204 includes a second hopper 215, a second feed tube 217, and a second nozzle 216. Typically, a first powder material 210 is dispensed from the first hopper 211 via the first feed tube 213 and the first nozzle 212. Similarly, a second powder material 216 is dispensed from the second hopper 215 via the second feed tube 213 and the second nozzle 214. A mirror 218 targets the energy source 208 or laser to form a molten pool on the substrate 220 and selectively bonds the first powder material 210 and / or the second powder material 212 in a desired pattern at the fusion zone or laser focusing zone 222. The substrate 220 is movable in three planes. The substrate 220 retracts along a first direction Y1 and then moves along directions X1, X2, Z1, and Z2 to deposit and bond continuous layers of the distributed first powder material 210 and / or second powder material 214 thereon until a desired object is formed, in this example, a precursor scaffold 300. The first powder material 210 can be a material conventionally used as a scaffold material. For example, and not limited to, the first powder material 210 can be stainless steel (e.g., SS316L), a cobalt-chromium alloy, a nickel-titanium alloy (e.g., NITINOL), magnesium and magnesium alloys, or combinations thereof. The term “cobalt-chromium” alloy as used herein includes alloys containing both cobalt and chromium. Generally, materials such as, but not limited to, cobalt-nickel-chromium alloys (MP35N, MP20N, and MP35NLT) and chromium-nickel-tungsten-cobalt alloys (“L605”) are types of materials included in the term “cobalt-chromium alloy” as used herein. The second powder material 214 can be a material used to modify the characteristics of various portions of the precursor scaffold, as described in more detail below. The following describes in more detail specific embodiments of materials that can be used as the second powder material 214.

[0030] The lamination or overlay bonding of the first powder material 210 and / or the second powder material 214 requires a lower layer support for the materials to be bonded. Typically, support is provided by the previously bonded material after the first material layer is deposited on the substrate 220. However, for certain medical devices such as stents, it is desirable that a large portion of the perimeter of the first band (part) of the device is not connected to the second band (part) of the device. However, in many embodiments, these connections cannot be excluded during additive manufacturing because subsequent layers require support built on these connections. Therefore, when such a stent is built vertically, it is desirable to build connections between a large portion or all of the crown of adjacent bands to provide support for subsequent material layers. Figure 2The microcoating system 200 is provided for illustrative purposes only and is not intended to limit the invention. Other microcoating systems are possible, including, but not limited to, microcoating systems with more or fewer powder delivery systems and systems in which an energy source is directed through a nozzle of the system.

[0031] The use of, for example, about Figure 2 The microcoating system 200 described Figure 1 The method will be described in this description, focusing on the formation of the scaffold. Figure 1 However, it should be understood that the following methods can be used. Figure 1 This method can be used to create other similar medical devices. In one embodiment, in Figure 1 In step 102, the micro-coating system 200 receives a dataset corresponding to a medical device such as the prosthesis scaffold 300, such as Figure 3 As shown. Specifically, the dataset contains information about the features of the precursor scaffold 300 from which the microcoating system 200 can form the precursor scaffold 300. For example, the dimensions and positions of the various parts of the precursor scaffold 300 can be part of the dataset, allowing the microcoating system 200 to form the precursor scaffold 300. For example, and not limited to, the dataset can be a 3D printable file, such as an STL file. STL (StereoLithography) is a file format inherent to stereolithography CAD software created by 3D Systems. STL is also known as Standard Triangle Language and Standard Tessellation Language. Many software packages used in additive manufacturing support this file format.

[0032] exist Figure 1 In step 104 of the method, the microcoating system 200 forms the precursor scaffold 300, such as Figure 3 As shown. In step 104, the microcoating system 200 lays down a continuous layer or coating of one or more powders of the desired material to construct a precursor scaffold 300 from a series of cross sections. Figure 3 An embodiment of a precursor support 300 is shown. According to an embodiment of the invention, the precursor support 300 is constructed via a microcoating such that the precursor support 300 is vertically constructed on a substrate 220. The substrate 220 can be any material suitable for use in the environment of a microcoating fabrication process and for use with materials used in a microcoating fabrication process. In the illustrated embodiment, the precursor support 300 includes a plurality of annular elements or bands 310 formed of a first material. Bands 310 may also be referred to as cylindrical elements or portions. Figure 3In one embodiment, the precursor support 300 includes eight straps 310a-310h, although more or fewer straps 310 may be used. Each strap 310 is arranged adjacent to another strap 310 along the longitudinal axis LA to form a tube or cylinder. Each strap 310 is a corrugated element formed by a plurality of struts 312 connected together by bends or crowns 314. Furthermore, the crowns 314 of adjacent straps 310 are connected to each other by at least one first connecting portion 324 and a plurality of second connecting portions 326. Further, in one embodiment, the first strap 310 may be separated from the substrate 220 by a strut or connecting portion 330, such as Figure 3 As shown, it can also be constructed using a microcoating manufacturing process.

[0033] Furthermore, in some embodiments, it is desirable that a portion of the pre-existing stent is radiopaque. Therefore, in some embodiments, step 104 includes making certain portions of the pre-existing stent 300 radiopaque, as will be described in more detail below. The term "radiopaque" refers to the ability of a material to absorb X-rays. Very few materials allow 100% of X-rays to pass through, and very few materials absorb 100% of X-rays. For the purposes of this disclosure, "radiopaque" refers to those materials and substances that have suitable visibility for stent surgery when imaged by an X-ray imaging apparatus such as, but not limited to, a fluorescence spectrometer.

[0034] The difference between the first connecting portion 324 and the second connecting portion 326 is that the first connecting portion 324 is configured to remain in place, thereby connecting adjacent crown portions 314 to each other, while the second connecting portion 326 is configured to be removable from the front support 300. Similarly, the support rod 330 is configured to be removable from the front support 300 so that the band 310a closest to the substrate 220 is not damaged when the front support 300 is separated from the substrate 220. Although in Figure 3 The illustration shows a specific embodiment of the precursor stent 300, but different precursor stents can be formed using microcoating manufacturing processes. For example, and not limited to, additional connectors can be used, the strips can be tilted, different strips can have different features (such as different thicknesses), additional features such as surface features, notches, etc., can be added, and other stent design differences that can be manufactured using microcoating manufacturing processes can be employed.

[0035] As described above, each crown 314 of the band 310 is connected to a corresponding crown 314 of an adjacent band 310 via a first connecting portion 324 or a second connecting portion 326. However, as described above, for certain applications, it will be desirable for some crowns 314 of the band 310 to be independent of or not connected to corresponding crowns 314 of adjacent bands 310. Also as described above, when forming the precursor support 300 via microcoating, the second connecting portion 326 cannot be simply excluded from the precursor support 300, because excluding the second connecting portion 326 when the precursor support is vertically constructed on the substrate 220 would lead to instability between adjacent bands 310 during the microcoating manufacturing process. For example, and not limitingly, if in Figure 3 If the first band 310a and the second band 310b only include a first connecting portion 324, then the second band 310b will tend to move towards the first band 310a at the crown 314 due to gravity without a connecting portion. This tendency will adversely affect the ability to construct a stent with the desired characteristics.

[0036] therefore, Figure 1 Step 106 of method 100 is to process the precursor support 300 to remove a plurality of second connecting portions 326 between the crown portions 314 of adjacent bands 310. Figure 3 In a specific embodiment, the second connector 326 is selected to be removed, such that only a single first connector 324 is disposed between each strip 310 and its adjacent strip 310. However, the number and type of the second connector 326 to be removed can be selected based on various factors, including but not limited to the desired flexibility of the resulting support.

[0037] As described above, it is desirable to minimize the difficulty of removing the second connector. Therefore, in embodiments of this application, the second connector 326 is formed by abruptly transitioning from the first material to the second material or by functionally grading the first and second materials such that the second connector 326 is more brittle than the first connector 324 and the band 310 of the precursor support 300. Similarly, the support rod 330 can be formed using a similar method. Since the second connector 326 and the support rod 330 are more brittle than the band 310 and the first connector 324, they can be easily removed by mechanical, chemical, or other suitable methods.

[0038] Functional grading is a structural change of two materials over a given volume. In short, functional grading alters the ratio or mixture of a first material and a second material. This functional grading results in a corresponding change in the properties of the final material. Therefore, specific properties can be imparted to specific regions of a structure formed using a microcoating process that employs functional grading. For example, and not limited to, functional grading can be used to increase strength, stiffness, radiopaque linearity, embrittlement, or corrosion resistance relative to the first or base material or alloy. As an example, in Figure 1 In embodiments of the method, it is desirable to embrittle or make the second connection portion 326 of the precursor support 300 more brittle, so that the second connection portion 326 can be easily removed from the precursor support 300 during processing in step 106. Thus, each second connection portion 326 can be embrittled through functional gradation, so that each second connection portion 326 can be easily removed without adversely affecting the band 310 and the plurality of first connections 324. Embodiments of materials and methods for embrittlement of the second connection portion 326 and embodiments for making a portion of the precursor support 300 non-transparent are provided below.

[0039] In the example explained below, cobalt is used as the first powder material 210, and tantalum is used as the second powder material 214. However, this is not intended to be limiting. Cobalt is used as the first powder material 210 in this example because cobalt is the main metal in cobalt-chromium alloys such as MP35N. However, as those skilled in the art will understand, the properties of MP35N are different from those of cobalt. Furthermore, since tantalum is an example of a radiopaque material used in medical devices, tantalum is used as the second powder material 214 in this example. Furthermore, due to the cobalt-tantalum phase diagram ( Figure 6 Therefore, cobalt and tantalum were used in the embodiments. As those skilled in the art will understand, the principles explained below can be used with other materials, such as those listed above and below. For the materials selected as the first powder material 210 and the second powder material 214, reference can be made to the phase diagram of the two selected materials, which is similar to... Figure 6 The cobalt-tantalum phase diagram in the figure is used to functionally classify the two materials using the principles discussed below to achieve embrittlement and / or radiopaque linearity, as described in more detail below.

[0040] In an example that facilitates the removal of the second connector 326, as described above, the first powder material 210 is cobalt or a cobalt alloy. The second powder material 214 is tantalum. The strip 310 of the precursor support 300 and the first connector 324 are formed of the first powder material 210. In one example, Figure 3The multiple second connecting portions 326 are formed by abruptly transitioning from the first powder material 210 to the second powder material 214. Therefore, when the substrate 220 of the microcoating system 200 moves to form a layer of strips 310 and first connecting portions 324, the first powder material 210 is dispensed from the first hopper 211. When a layer of one of the second connecting portions 326 is to be formed, the second powder material 214 is dispensed from the second hopper 215. This is a sudden or stepwise transition from the first powder material 210 to the second powder material 214, as... Figure 4 The transition style diagram is shown below. Figure 4 The slash mark 340 indicates the relative level of the first material (cobalt or cobalt alloy) and the second material (tantalum). Therefore, in Figure 4 In the example, the spaced-apart diagonal markings 340 represent the first material (cobalt), while the adjacent diagonal markings represent the second material (tantalum). A sudden transition from 100% cobalt to 100% tantalum causes embrittlement in this region. Similarly, a sudden transition from 100% tantalum to 100% cobalt causes embrittlement in this region. In one embodiment, these transition regions are located at the transition from the crown 314 to the second connection 326, as... Figure 4 As shown. Therefore, the connection between the second connection 326 and the adjacent crown 314 is fragile, making the connection easy to break. Therefore, the second connection 326 can be mechanically removed by breaking the connection between the second connection 326 and the adjacent crown 314. Furthermore, since the second connection 326 does not contain any of the first powder material 210 in this example, the second connection 326 can be removed by other methods such as chemical etching, as described in U.S. Patent No. 9,114,032 assigned to Medtronic Vascular, Inc., the entire contents of which are incorporated herein by reference. The support 330 can be formed in the same manner for easy removal from the first band 310a.

[0041] exist Figure 5In another example shown, a harmful second-phase intermetallic compound is formed by functionally grading a first powder material 210 and a second powder material 214 to form each second connection 326', thereby embrittlement of multiple second connections 326'. A "harmful second-phase intermetallic compound" refers to an intermetallic compound of sufficient size and quantity to embrittle each second connection 326'. This harmful intermetallic compound is larger than the nanometer size. The second-phase intermetallic compound is a crystalline structure of an intermediate phase, formed by functionally grading a first material and a second material in a specific ratio within a specific temperature range. Second-phase intermetallic compounds differ from any basic material. They consist of a fixed composition and are similar to alloys, but the bonding portions between the different atoms in a second-phase intermetallic compound are ionic. This results in properties and characteristics different from conventional alloys. Therefore, second-phase intermetallic compounds have their own crystalline structure and are almost always brittle.

[0042] exist Figure 5 In the example shown, the first powder material 210 is cobalt, and the second powder material 214 is tantalum. Similar to the embodiments described above, a strip 310 including pillars 312 and top 314, a first connector 324, and a second connector 326' can be formed using a microcoating system 200. The first powder material 210 is dispensed from the first hopper 211 as the substrate 220 moves to form the layer of the strip 310 and the first connector 324. At the location of the second connector 326', both the first powder material 210 and the second powder material 214 are... Figure 5 The proportions shown are consistent. Therefore, in this example, the crown 314 adjacent to the second connection 326' is 100% cobalt. Figure 5 As shown, the initial layer of each second connector 326' is formed of 53% cobalt and 47% tantalum. Then, as... Figure 5 As shown, the middle portion of each second connecting part 326' is formed of 15% cobalt and 85% tantalum. Then, as... Figure 5 As shown, the end adjacent to another crown 314 is formed of 53% cobalt and 47% tantalum.

[0043] Figure 6 This is a cobalt-tantalum phase diagram. As can be seen at 350, under certain conditions, 53% cobalt and 47% tantalum are used to form the second-phase intermetallic compound Co7Ta2. Similarly, as shown at 351, under certain conditions, 15% cobalt and 85% tantalum are used to form the second-phase metallic compound CoTa2. Each of these second-phase intermetallic compounds is hard and brittle. Therefore, by forming each second connection 326' from a combination of the first powder material 210 and the second powder material 214, two harmful second-phase intermetallic compounds are formed, causing each second connection 326' to become embrittled, as... Figure 5The transition pattern is shown. Alternatively, each second connection 326' may be formed from only one harmful second-phase intermetallic compound. Figure 5 In the transitional style, the hash mark 342 to the left of the functional grading ratio indicates the relative ratio of cobalt and tantalum. The spaced diagonal marks 342 are mostly or entirely cobalt, and as the diagonal marks 342 move closer together, the proportion of tantalum increases relative to cobalt.

[0044] As mentioned above, Figure 1 Step 106 of method 100 is to process the precursor support 300 to remove a plurality of second connectors 326 between the crown 314 of the adjacent band 310 and the plurality of struts 330 without adversely affecting the adjacent band 310 and the plurality of first connectors 324. Figure 4 In an example of the second connection portion 326, where the second connection portion 326 is formed by a sudden material transition, multiple second connection portions 326 can be removed by methods such as, but not limited to, chemical dissolution or chemical etching. However, in Figure 5-6 In the example, where the second connection 326' is embrittled through functional gradation to form a harmful second-phase intermetallic compound, the second connection 326' can be removed by methods such as, but not limited to, laser ablation, electrical discharge machining (EDM), water jetting, electron beam, focused ion beam (FIB), micromachining, and other similar methods. Furthermore, the support rod 330 can be removed by methods similar to those used to remove the second connections 326, 326'.

[0045] As previously mentioned, some materials commonly used in stents are not radiopaque. Therefore, radiopaque strips or other radiopaque devices are sometimes added to stents to aid in visual inspection. In embodiments of this application, the functional grading of the first powder material 210 and the second powder material 214 can be used to impart radiopaque capabilities to various parts of a medical device such as a stent. Specifically, functional grading can be used to add radiopaque linearity to various parts of the pre-existing stent 300 configured to remain in place. In some embodiments, functional grading can be used to add radiopaque linearity to low-stress components of the pre-existing stent 300, such as struts 312 and / or multiple first connectors 324.

[0046] In one example, by using a first powder material 210 (cobalt) and a radiopaque second powder material 214 (tantalum) in such a way as Figure 7 The pattern shown is functionally hierarchical, with multiple first connecting portions 324' made non-transparent. Figure 7In the example, functional grading is performed to minimize the formation of the aforementioned cobalt-tantalum second phase (i.e., to minimize the formation of Co7Ta2, Co6Ta7, and CoTa2). Minimizing the formation of the second-phase intermetallic compound means that the second-phase intermetallic compound has a sufficiently small quantity and size (nanoscale or smaller) without causing embrittlement. Therefore, multiple first connectors 324' can be made radiopaque without becoming embrittled. Figure 7 In the illustrated embodiment, each first connector 324' adjacent to the corresponding crown 314 of the corresponding band 310 is typically 100% cobalt. When each first connector 324' is formed layer by layer using a microcoating manufacturing process, the ratio of the second powder material 214 to the first powder material 210 increases. Figure 7 In the example, the middle portion of the first connector 324' is 100% tantalum. When the first connector 324' is formed such that each layer moves from the middle portion to the corresponding crown 314 of the adjacent strip 310, the ratio of the second powder material 214 to the first powder material 210 decreases, such that near the corresponding crown 314 of the adjacent strip 310, the first connector is 100% first powder material (cobalt). Figure 7 The diagonal mark 344 on the left side of the functional grading pattern indicates the ratio of the first material to the second material, and the radiopaque linearity of the material compound compared to the radiopaque linearity of the first material. Therefore, diagonal marks 344 that are far apart represent 100% of the first material (cobalt), and the resulting material is not radiopaque. As the diagonal marks 344 move closer together, the ratio of the second material increases while the ratio of the first material decreases. Furthermore, as the diagonal marks move closer together, the radiopaqueness of the resulting material increases.

[0047] Figure 8 Another example of a functional hierarchy that can be used at a plurality of first connectors 324' is shown, these first connectors being configured to retain such that the first connectors 324' are non-transparent. Figure 7 Similar to the previous embodiment, functional grading is performed to minimize the formation of the second phase of the first and second materials, in this case, the formation of the second phase of cobalt and tantalum (i.e., minimizing the formation of Co7Ta2, Co6Ta7, and CoTa2). Therefore, the plurality of first connecting portions 324' can be made non-transparent and non-brittle. Figure 8 In the illustrated embodiment, each first connector 324' adjacent to the corresponding crown 314 of the corresponding band 310 is typically 100% cobalt. The ratio of the second powder material 214 to the first powder material 210 increases as each first connector 324' is formed layer by layer using a microcoating manufacturing process. Figure 7In the example, the middle portion of the first connector 324' is approximately 5% cobalt and 95% tantalum. When the first connector 324' is formed such that each layer moves from the middle portion to the corresponding crown 314 of the adjacent band 310, the ratio of the second powder material 214 to the first powder material 210 decreases, such that near the corresponding crown 314 of the adjacent band 310, the first connector is 100% the first powder material (cobalt). Figure 8 The diagonal marking 346 to the left of the functional gradient distribution ratio indicates the ratio of the first material to the second material, and the radiopaqueness of the material compound compared to the radiopaqueness of the first material. Therefore, diagonal markings 346 that are far apart represent 100% of the first material (cobalt), and the resulting material is not radiopaque. As the diagonal markings 346 move closer together, the ratio of the second material increases while the ratio of the first material decreases. Furthermore, as the diagonal markings move closer together, the radiopaqueness of the resulting material increases.

[0048] Figure 9 Another example of a functional hierarchy that can be used at a plurality of first connectors 324' is shown, these first connectors being configured to retain such that the first connectors 324' are non-transparent. Figure 7 and 8 Similar to the previous embodiment, functional grading is performed to minimize the formation of the second phase of the first and second materials, in this case, the formation of the second phase of cobalt and tantalum (i.e., minimizing the formation of Co7Ta2, Co6Ta7, and CoTa2). Therefore, the plurality of first connecting portions 324' can be made non-transparent and non-brittle. Figure 9 In the illustrated embodiment, each first connector 324' adjacent to the corresponding crown 314 of the corresponding band 310 is typically 100% cobalt. The ratio of the second powder material 214 to the first powder material 210 increases as each first connector 324' is formed layer by layer using a microcoating manufacturing process. Figure 9 In the example, the middle portion of the first connector 324' is approximately 100% tantalum. When the first connector 324' is formed such that each layer moves from the middle portion to the corresponding crown 314 of the adjacent strip 310, the ratio of the second powder material 214 to the first powder material 210 decreases, such that near the corresponding crown 314 of the adjacent strip 310, the first connector is 100% first powder material (cobalt). Figure 9 Implementation examples and Figure 7 The embodiments are largely similar, except that the transition from 100% first material (cobalt) to 100% second material (tantalum) is more gradual. Figure 9The diagonal marking 348 to the left of the functional gradient distribution ratio indicates the ratio of the first material to the second material, and the radiopaqueness of the material compound compared to the radiopaqueness of the first material. Therefore, diagonal markings 348 that are far apart represent 100% of the first material (cobalt), and the resulting material is not radiopaque. As the diagonal markings 348 move closer together, the ratio of the second material increases while the ratio of the first material decreases. Furthermore, as the diagonal markings move closer together, the radiopaqueness of the resulting material increases.

[0049] It has been described that at least some of the plurality of first connecting portions 324' that are nontransparent are configured to be retained. Figure 7-9 Examples of these embodiments. However, these embodiments are not limited to multiple first connections. In other embodiments, the precursor support 300 may be configured such that other portions remain radiopaque. For example, as Figure 10 As shown, at least some of the struts 312' of the anterior support 300 can be referenced above. Figure 7-9 The same square does not transmit light. Figure 10 An exemplary strip 310 is shown, flattened for simplified viewing. The exemplary strip 310 may be... Figure 3 Any or all of the bands 310. In some cases, it is desirable that all or some of the struts 312' of some or all of the bands 310 be radiopaque. For example, and not limitingly, it is desirable to make the struts of the end bands (bands 310a and 310h) radiopaque so that the ends of the stents are visible under fluorescence examination. In embodiments where the struts 312' are formed as radiopaque, see [reference needed]. Figure 10 As the substrate 220 moves to form the crown 314a, the first powder material 210 is deposited on the previous layer and melted by the laser 208. This occurs for each layer of the crown 314a. As the layers build up and begin to form pillars 312', the second powder material 214 is gradually added, and the amount of the first powder material 210 is gradually reduced to form the layers of pillars 312'. The gradual increase / decrease can be determined according to... Figure 7-9 Any of the embodiments. Approximately reaching the center of each pillar 312', the amount of the second powder material 214 is reduced, and the amount of the first powder material 210 is increased to form a layer toward the crown 314b until the layer at the crown 314b is 100% the first powder material. This gradual reduction / increase may also be based on… Figure 7-9 The resulting support 312' is non-transparent and does not adversely affect the strength, stiffness, and overall performance of the precursor support 300.

[0050] Various embodiments for manufacturing the precursor support 300 have been discussed above. (As mentioned above regarding...) Figure 1As described in step 104 of the method, a plurality of second connectors 326, 326' and optional struts 330 are removed from the anterior support 300. With the plurality of second connectors 326, 326' and struts 330 removed, the anterior support 300 becomes... Figure 11-13 The bracket 400 is shown. The bracket 400 includes multiple annular elements, sections, or bands 410. Figure 11 In one embodiment, the support 400 includes eight bands 410, which correspond to the eight bands 310 of the anterior support 300. However, more or fewer bands 410 may be used. Each band 410 is arranged adjacent to another band 410 along a central longitudinal axis LA to form a tube or cylinder. Each band 410 is a waveform formed by a plurality of struts 414 connected together by bends or crowns 412. At least one crown 414 of each band 410 is connected to a corresponding crown 414 of an adjacent band 410 via a first connecting portion 424. Figure 12 A close-up view of a first connecting portion 424 is shown, which connects the crown portions 414 of adjacent bands 410 to each other. Figure 13 As shown, at other crown portions, a gap 428 is provided between the crown portion 414 and the corresponding crown portion 414 of the adjacent band 410. It should be understood that if the method used as described above is used to prevent the first connecting portion 324' from transmitting light, then... Figure 11-13 The illustrated support 400 may have a first, non-transparent connection 424. Similarly, if the method used as described above is used to make the corresponding struts 312' of the precursor support 300 non-transparent, then at least some of the struts 412 of the support 400 may be non-transparent.

[0051] The specific embodiments described above for functionally grading the first and second materials to make the connection brittle or to make the connection or support radiopaque use cobalt and tantalum as the first and second materials, respectively. However, these are examples, and other materials may be used according to this disclosure. For example, and not limited to, the first material 210 may be stainless steel and stainless steel alloys (e.g., SS316L), cobalt-chromium alloys, nickel-titanium alloys (e.g., NITINOL), magnesium and magnesium alloys, or combinations thereof. The term "cobalt-chromium alloy" as used herein includes alloys containing both cobalt and chromium. Generally, materials such as, but not limited to, cobalt-nickel-chromium alloys (MP35N, MP20N, and MP35NLT) and chromium-nickel-tungsten-cobalt alloys ("L605") are types of materials included in the term "cobalt-chromium alloy" as used herein. Further, the second material may be platinum, gold, tantalum, and other radiopaque materials known to those skilled in the art. Moreover, the exemplary functional grading ratio patterns and transition rates provided by the method of manufacturing the precursor support 300 are merely examples and are not intended to be limiting. Other functional grading systems, system ratio patterns, and transition rates may be employed based on this application.

[0052] Although the embodiments shown and described herein refer to crowns connected to corresponding crowns of adjacent bands on the anterior support, other connections between adjacent bands may be used. For example, and not limitingly, a crown of one band may be connected to a strut of an adjacent band, or to multiple struts of adjacent bands. Further, the first connection 324 and the second connection 326 may be angled relative to the longitudinal axis LA or may be curved.

[0053] Although the embodiments shown and described herein relate to a precursor stent having a strap, at least one first connector and a plurality of second connectors, the precursor stent being processed to form a stent, this is not intended to limit the method, and other medical devices can be manufactured using the methods described herein.

[0054] Furthermore, although various embodiments of the invention have been described above, it should be understood that they are presented as illustrative and exemplary rather than as limitations. It will be apparent to those skilled in the art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Therefore, the breadth and scope of the invention should not be limited by any of the exemplary embodiments described above, but should be defined only by the appended claims and their equivalents. It should also be understood that each feature of each embodiment discussed herein and each reference cited herein can be used in combination with features of any other embodiments. All patents and published documents discussed herein are incorporated herein by reference in their entirety.

Claims

1. A method of fabricating a stent comprising the steps of: forming a precursor stent (300) using a microcladding, wherein the precursor stent (300) comprises a plurality of bands (310) made of a first material disposed adjacent to one another, wherein each of the bands (310) is attached to an adjacent band by a plurality of first links (324, 324') configured to remain and a plurality of second links (326, 326') configured to be removed, wherein the plurality of second links (326, 326') are fabricated by functionally grading a first material to a second material to produce embrittlement in the plurality of second links (326, 326'); processing the precursor stent (300) to remove the plurality of second links (326, 326') without adversely affecting the bands (310) and the plurality of first links (324, 324').

2. The method of claim 1, wherein, the step of processing the precursor stent (300) to remove the plurality of second links (326, 326') includes mechanically removing the plurality of second links.

3. The method of claim 1, wherein, the second material is a radiopaque material.

4. The method of claim 1, wherein, the plurality of second links (326, 326') are fabricated by creating an abrupt transition between the first material and the second material.

5. The method of claim 1, wherein, the plurality of second links (326, 326') are fabricated by functionally grading the first material to the second material to form a deleterious second phase intermetallic compound to impart embrittlement to the plurality of second links (326, 326').

6. The method of claim 1, wherein, the first material is selected from the group consisting of cobalt-chrome alloy and stainless steel, and the second material is selected from the group consisting of tantalum, platinum, and gold.

7. The method of claim 1, wherein, at least one of the plurality of first links (324') is fabricated by functionally grading the first material to a third material, wherein the third material is a radiopaque material, such that the at least one of the plurality of first links (324') is radiopaque.

8. The method of claim 7, wherein, the step of functionally grading the first material to the third material for the at least one of the plurality of first links (324') includes gradually transitioning from a greater percentage of the first material to a greater percentage of the third material as layers of the at least one of the plurality of first links (324') are added, and then gradually transitioning back to the first material from the greater percentage of the third material as layers are added, such that formation of a second phase intermetallic compound in the at least one of the plurality of first links (324') is minimized.

9. The method of claim 7, wherein, the second material and the third material are the same material.

10. The method of claim 1, wherein, a portion of at least one of the plurality of bands (310) is fabricated by functionally grading the first material to a third material, wherein the third material is a radiopaque material, such that the portion of the at least one of the plurality of bands is radiopaque.

11. The method of claim 10, wherein, the third material and the second material are the same material.

12. The method of claim 10, wherein, The step of functionally grading the first material and the third material for the portion of the at least one of the plurality of bands (310) includes a proportion of gradually transitioning from the first material to the third material being greater than the first material and then gradually transitioning back from the third material being greater than the first material to the first material with the addition of layers, thereby minimizing the formation of a second phase intermetallic compound in the at least one of the plurality of bands (310).

13. A method of manufacturing a stent, comprising the steps of: forming a precursor stent (300) using microcladding, wherein the precursor stent (300) includes a plurality of bands (310) made of a first material configured adjacent to one another, wherein each of the bands (310) is attached to an adjacent band (310) by a plurality of first links (324, 324') configured to remain and a plurality of second links (326, 326') configured to be removed, wherein at least a portion of at least one of the plurality of bands (310) and at least one of the first links (324') is made radiopaque by functionally grading the first material with a radiopaque second material; processing the precursor stent (300) to remove the plurality of second links (326, 326') without adversely affecting the bands (310) and the plurality of first links (324, 324').

14. The method of claim 13, wherein, The step of functionally grading the first material and the radiopaque second material for the at least a portion of the at least one of the plurality of bands (310) and the at least one of the first links (324') includes a proportion of gradually transitioning from the first material to the radiopaque second material being greater than the first material and then gradually transitioning back from the radiopaque second material being greater than the first material to the first material with the addition of layers, thereby minimizing the formation of a second phase intermetallic compound in the at least a portion of the at least one of the plurality of bands (310) and the at least one of the first links (324').

15. The method of claim 13, wherein, The at least a portion of the at least one of the plurality of bands (310) and the at least one of the first links (324') includes a strut (312') of at least one of the plurality of bands (310).

16. The method of claim 13, wherein, The at least a portion of the at least one of the plurality of bands (310) and the at least one of the first links (324') includes at least one of the first links (324').

17. A precursor stent, comprising: a plurality of bands (310) made of a first material configured adjacent to one another; and a plurality of first connections (324, 324') connecting each of the bands (310) to an adjacent band (310) and a plurality of second connections (326, 326') connecting each of the bands (310) to an adjacent band, wherein the first connections (324, 324') are configured to remain and the plurality of second connections (326, 326') are made by functionally grading the first material to the second material to create embrittlement, such that the plurality of second connections (326, 326') are configured to be removed.

18. The precursor scaffold (300) of claim 17, wherein, The second material is a radiopaque material.

19. The precursor scaffold (300) of claim 17, wherein, The plurality of second connections (326, 326') include a sudden transition between the first material and the second material to impart embrittlement at a junction of each of the plurality of second connections (326, 326') and a corresponding band (310) of the plurality of bands (310).

20. The precursor scaffold (300) of claim 17, wherein, The plurality of second connections (326, 326') include a deleterious second phase intermetallic compound to impart embrittlement to the plurality of second connections (326, 326').

21. A medical device (400) comprising: a plurality of bands (410) made of a first material configured adjacent to one another; and at least one connection (424) connecting each of the bands (410) to an adjacent band (410), wherein the at least one connection (424) is made by functionally grading the first material to a second, radiopaque material.

22. The medical device (400) of claim 21, wherein, A second phase intermetallic compound is minimized in the at least one connection (424).

23. The medical device (400) of claim 21, wherein, The medical device is a stent.

24. A medical device (400) comprising: a plurality of bands (410) made of a first material configured adjacent to one another; and at least one connection (424) connecting each of the bands to an adjacent band, wherein at least a portion of at least one of the bands (410) is made by functionally grading the first material to a second, radiopaque material.

25. The medical device (400) of claim 24, wherein, The medical device is a stent.

26. The medical device (400) of claim 25, wherein, The plurality of bands (410) include struts (412) and crowns (414) coupling the adjacent struts (412) to one another by corresponding crowns (414), wherein the at least a portion of at least one band (410) is a strut (412) of the at least one band (410).

27. The medical device (400) of claim 26, wherein, A second phase intermetallic compound is minimized in the struts (412).

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