Patent Application
20200197669
This application relates to guidewires formed by metallurgical joining of components of shape memory and superelastic nickel titanium alloys to other components of shape memory and superelastic nickel titanium alloys, and/or to other biocompatible metals or metal alloys, by reactive eutectic brazing.
U.S. Pat. 7,896,222 (the “222 patent”) discloses reactive eutectic brazing for joining of shape memory and superelastic nickel titanium alloys to each other or other metals or metal alloys. As disclosed in the '222 patent, niobium reacts with Nitinol shape memory alloys to produce a eutectic liquid that may be used to form a strong metallurgical joint. Thus, pure niobium can be used as a braze-foil by way of its well-understood contact melting reaction with NiTi (nitinol) alloys. Niobium is brought into contact with a NiTi alloy and heated to 1170 degrees C., and then quenched, in order to effect the braze. Pure niobium alloyed with another metal capable of forming an alloy with niobium is also disclosed.
However, how and where to apply the required niobium to form the joint requires great care as the niobium does not melt by itself. It needs to be in direct contact with NiTi for melting to occur, and a very significant amount of NiTi enters the eutectic melt as well. When joining NiTi alloys, it is undesirable to bring niobium in direct contact with the NiTi objects to be joined, because those same objects will be significantly attacked as the contact melting reaction proceeds. When pure niobium reacts with a NiTi alloy, approximately two volumes of NiTi metal will enter the eutectic liquid for each volume of niobium in the reaction. The amount of niobium also requires great care as too much niobium can damage the components to be joined and too little niobium could result in an insufficiently strong joint causing fracture of the device. Therefore, a balance needs to be achieved between these opposing factors.
Thus, if the location, form, and amount of added niobium metal are not carefully controlled, deleterious attack of the structures-to-be-joined can occur. Also, the capillary flow of the eutectic liquid must be managed properly so that eutectic liquid metal flows to regions of the joint structure where it is needed for formation of the joint. Therefore, the need exists for connecting such components without damaging the components to be joined while still providing a sufficiently strong joint connecting the components.
Additionally in forming small devices such as guidewires or other medical devices, the processes for applying niobium to the small components in the desired quantity and correct locations for formation of a strong metallurgical joint (by reactive brazing) can be difficult and expensive. Therefore, it would be advantageous to provide a process to simplify and reduce the cost of manufacturing such medical devices using the reactive brazing process of the '222 patent, while ensuring a sufficiently strong and effective joint is formed. Providing such processes would enable manufacture of guidewires or other medical devices of different components of varying properties.
The present invention provides metallurgical joining of shape memory and superelastic nickel titanium alloys to each other, and/or to other biocompatible metals or metal alloys, by reactive eutectic brazing to form guidewires or other medical devices of varying properties. That is, the guidewire can be formed of components of different materials having different stiffnesses/malleability or other properties to provide a guidewire with desired properties at different portions (regions) of the guidewire. Thus, the guidewires can be formed of two or more components such as long thin tubes or wires made from dissimilar biomedical alloys.
In accordance with one aspect of the present invention, the guidewire is formed by a first component, which forms a niobium-coated NiTi alloy sleeve, and a second component (and in some embodiments additional components) of a different property positioned partially within the first component. In some embodiments, the outer sleeve component has a liner tube that abuts the inner component for forming a butt joint. The first component and/or the second component can be solid (only having a single diameter) or alternatively hollow (having an OD and ID) as described in more detail below.
In accordance with one aspect of the present invention, two components are joined end to end by a niobium-coated NiTi alloy sleeve. In accordance with another aspect of the present invention, a niobium-coated sleeve is joined to a single inner component. In accordance with yet another aspect of the present invention, the niobium coated sleeve forms a connector for two axially spaced longitudinally aligned components. In accordance with another aspect of the present invention, multiple components are joined by multiple niobium sleeves forming multiple joints along the device. Each of these variations is discussed in detail below.
In some embodiments, a cylindrical niobium-coated NiTi-alloy sleeve is utilized to join and reinforce two components such as long thin tubes made from dissimilar biomedical alloys. Differently configured sleeves and different geometries are discussed herein. The components joined can be solid (only having a single diameter) or alternatively hollow (having an OD (outer diameter) and an ID (inner diameter)).
Three different process protocols are disclosed herein. The first process specifies a set of guidelines for a niobium metal coating to be applied, in a batch process, to a metal feed stock. The second process describes a laser-micromachining procedure for fenestrating, slotting, and dicing this feed stock (after coating with niobium or in some embodiments prior to coating with niobium) into many tiny sleeves, preferably cylindrical, these later being used to create and reinforce butt-joints in hypodermic tubing segments (or other components, e.g., wires) of dissimilar biomedical alloys. The third process describes a galvo-controlled laser based vacuum brazing process, based on the eutectic brazing U.S. Pat. No. 7,896,222, however, here it utilizes the niobium coated cylindrical sleeve to effect a metallurgical, robust, and hermetic joint between dissimilar tubes or wires. In some embodiments, as described below, the niobium metal coating can be applied after separating the feed stock into 10 individual sleeves.
In accordance with one aspect of the present invention, a method of joining two metal components is provided comprising a) positioning a first metal component in a first end of a sleeve, the sleeve composed of a nickel titanium alloy and having niobium deposited thereon; b) positioning a second metal component in a second end of the sleeve; and c) increasing the temperature of the sleeve so the niobium reacts to form a joint joining the first and second components.
In some embodiments, the first and second components are laser heated and heat transfers to the sleeve to increase the temperature.
In some embodiments, the first component is composed of one of platinum, tantalum or stainless steel, e.g., annealed 316 or 304 stainless steel, or stainless steel plated or clad coated with NiTi, Pt or Ta (which expands the temperature processing window) and the second component is composed of a shape memory or superelastic nickel titanium alloy. In some embodiments, the first component is composed of a shape memory or superelastic nickel titanium alloy.
In some embodiments, the sleeve is composed of a shape memory or superelastic nickel titanium alloy.
In some embodiments, the first component has a flexibility less than a flexibility of the second component at room temperature. In some embodiments, the first component has a flexibility less than a flexibility the second component at body temperature. The first and second components can have other varying properties.
In some embodiments, the first and second components are placed with ends in abutment within the sleeve prior to melting. The sleeve in preferred embodiments, avoids direct contact of the niobium and the first and second components underlying the sleeve.
In some embodiments, the sleeve has a plurality of fenestrations (openings) in a wall of the sleeve for flow of the melted niobium into contact with a surface of the first and second components underlying the sleeve. Various placements/arrangements and number of the fenestrations are disclosed. In some embodiments, the plurality of fenestrations are spaced from edges of the sleeve and spaced from the center point of the sleeve.
In some embodiments, the sleeve has a slot at the first and second ends for flow of eutectic liquid into a gap between the inner diameter of the sleeve and the outer diameter of the first and second components.
In accordance with another aspect of the present invention, a method of forming a joint between a first component composed of nickel titanium alloy and a second component composed of a biocompatible metal or metal alloy is provided, the method comprising placing a niobium coated sleeve over a region of the first and second components and reactively brazing the sleeve to the first and second components to form a brazed joint between the first and second components.
In some embodiments, the method further includes the step of placing the first and second components within opposing ends of the sleeve and in end to end abutment prior to reactive brazing. In some embodiments, during reactive brazing, the niobium flows around edges of the sleeve and into a gap between the inner surface of the sleeve and outer surface of the components. In some embodiments, during reactive brazing, the niobium flows through openings in the sleeve, the openings communicating with an outer surface of the first and second components.
In some embodiments, the biocompatible metal is a nickel titanium alloy; in other embodiments, the biocompatible metal is one of platinum, titanium or stainless steel coated or plated with another metal or alloy of the foregoing. In some embodiments, the first and second components are superelastic and/or shape memory.
In some embodiments, a ratio of niobium coating thickness to a sleeve wall thickness is ≤½; in other embodiments it is less than ¼; and in other embodiments the niobium coating thickness is between about 1% and about 15% of the sleeve wall thickness. In some embodiments, the niobium coating thickness on the sleeve is between one half the sleeve wall thickness at maximum and one half the thickness of the sleeve to inner component gap.
In accordance with another aspect of the present invention, a method of forming niobium coated nickel titanium alloy sleeves for use for joining a first component of shape memory or superelastic material to a second component of a biocompatible metal is provided, the method comprising:
In some embodiments, the individual tubes have a first opening at a first end to receive the first component and a second opening at a second end to receive the second component so the tubes overlie a region of the first and second components.
In accordance with another aspect of the present invention, a medical device is provided having a first region having a first property, a second region having a second property different than the first property and a joint formed by a niobium coated nickel titanium alloy sleeve joined, e.g., melted, onto a first section of the first region and a second section of the second region.
In some embodiments, the device includes a third region of a third property different than the first property and the second property, and a second joint is formed by a second niobium coated nickel titanium sleeve joined, e.g. melted, onto a third section of the second region and a fourth section of the third region.
In some embodiments, the first property is a first stiffness (Young's modulus) and the second property is a second stiffness greater than the first stiffness. In other embodiments, the first property is a first yield stress and the second property is second yield stress greater than the first yield stress. In some embodiments, the first region is distal of the second region; in other embodiments, the second region is distal of the first region. With shape memory, the stiffness changes with temperature.
In accordance with another aspect of the present invention, a medical device is provided having a first component having a first property, a second component having a second property different than the first property and a nickel titanium sleeve bridging the first and second component. The device has a first joint formed by the nickel titanium alloy sleeve having niobium thereon at a first end melted onto a first section of the first component and a second joint formed by the nickel titanium alloy sleeve having niobium thereon at a second end melted onto a second section of the second component.
In some embodiments, the sleeve has a flexibility less than a flexibility of the first component.
In some embodiments, the first component is a metal braided structure.
In accordance with another aspect of the present invention, a medical device is provided having a first region, a second region and a third region, wherein the Af temperature of each of the regions is different, and at least the first region is composed of a nickel titanium alloy and the first and second regions are formed by different components, the first and second components each containing niobium thereon.
In accordance with another aspect of the present invention, a product by a process is provided comprising a medical device formed by a laser brazing process, the device formed by first and second components joined together by a nickel-titanium alloy sleeve having niobium thereon and laser brazed to react and melt to flow to the first and second components extending into the sleeve thereby forming a joint to join the first and second components.
In some embodiments, the sleeve avoids direct contact with the niobium and the first and second components extending into the sleeve. Preferably, the niobium for reactive brazing is not applied to the first and second components extending into the sleeve. The sleeve can be coated by various processes such as by a PVD process of sputtering.
In some embodiments, the ratio of niobium coating thickness to a sleeve wall thickness is ≤½ and the niobium coating thickness on the sleeve is between one half the sleeve wall thickness at maximum and one half the thickness of the sleeve to inner component gap.
In accordance with another aspect of the present invention, a guidewire is provided having a first region having a first property, a second region having a second property different than the first property and a joint formed by a niobium coated nickel titanium alloy sleeve or coupler joined onto a first section of the first region and a second section of the second region.
In some embodiments, the first property is a first stiffness and the second property is a second stiffness greater than the first stiffness. In some embodiments, the first property is a first transition temperature and the second property is a second transition temperature.
In some embodiments, the sleeve or coupler is composed of a shape memory or superelastic nickel titanium alloy. In some embodiments, the first region and the second region are composed of a shape memory or superelastic nickel titanium alloy. In some embodiments, the first region has an austenitic finish temperature different from the second region.
The guidewire can include in some embodiments a third region composed of a core and a coil positioned over the core, the core having a third property different than the second property and joined to the second region by a second niobium coated nickel titanium alloy sleeve or coupler. In some embodiments, the core has a taper and the coil is positioned over the taper. In some embodiments, the core is composed of a nickel titanium alloy. The third region can be distal of the second region and more flexible than the second region.
In accordance with another aspect of the present invention, a guidewire is provided having a first component having a first property and a second component having a second property different than the first property. The second component is composed of a shape memory material or superelastic nickel titanium alloy and joined to the first component, the first component composed of a shape memory or superelastic nickel titanium alloy. The second component is more flexible than the first component.
In some embodiments, the second component has a tapered region tapering distally, and a coil is positioned over the tapered region. In some embodiments, the first and second components are connected at a joint formed by a niobium coated nickel titanium alloy sleeve or coupler joined onto a first section of the first component and a second section of the second component.
The guidewire in some embodiments can include a third component joined to the first component and extending proximally thereof, the third component having a stiffness greater than a stiffness of the first component. In some embodiments, the first component has an austenitic finish temperature different from the second component.
In accordance with another aspect of the present invention, the first and second components are joined by a niobated coupler, e.g., a niobated coupler bead, interposed between the components and aligned with the components, and the temperature is increased so the niobium reacts to form a joint between the two components.
In accordance with another aspect of the present invention, the first and second components have niobated ends which are placed in abutment and the temperature is increased so the niobium reacts to form a joint between the two components.
In accordance with another aspect of the present invention, a method of forming a guidewire is provided comprising the steps of:
a) positioning a first metal component in a first end of a first sleeve, the first sleeve composed of a nickel titanium alloy and having niobium deposited thereon;
b) positioning a second metal component in a second end of the first sleeve;
c) increasing the temperature of the first sleeve so the niobium reacts to form a first joint joining the first and second components.
d) either before or after step (c), positioning the second metal component in a first end of second sleeve and positioning a third metal component in the second end of a second sleeve, the second sleeve composed of a nickel titanium alloy and having niobium deposited thereon; and
e) increasing the temperature of the second sleeve so the niobium reacts to form a second joint joining the second and third components.
In some embodiments, the third component is composed of a shape memory or superelastic nickel titanium alloy. In some embodiments, the first, second and third components have different stiffnesses. In some embodiments, the first, second and third components have different austenitic finish temperatures.
In some embodiments, the first sleeve has a slot at the first and second ends for flow of eutectic liquid into a gap between an inner diameter of the first sleeve and an outer diameter of the first and second components.
In accordance with another aspect of the present invention, a method of forming a guidewire is provided comprising:
In accordance with another aspect of the present invention, a method of forming a guidewire is provided comprising a) positioning a first metal component in abutment with first end of a second metal component, the first component composed of a nickel titanium alloy, the first and second components having niobium deposited on an end thereof; and b) increasing the temperature of the ends of the first and second components so the niobium reacts to form a first joint joining the first and second components;
So that those having ordinary skill in the art to which the subject invention appertains will more readily understand how to make and use the surgical apparatus disclosed herein, preferred embodiments thereof will be described in detail hereinbelow with reference to the drawings, wherein:
As disclosed in U.S. Pat. No. 7,896,222, niobium reacts with Nitinol shape memory alloys to produce a eutectic liquid that may be used to form a strong metallurgical joint. Thus, pure niobium can be used as a braze-foil by way of its well-understood contact melting reaction with NiTi (nitinol) alloys. Niobium is brought into contact with a NiTi alloy and heated to 1170 degrees C., and then quenched, in order to effect the braze.
How and where to apply the required niobium requires great care. Unlike a solder, or a conventional braze foil, the niobium does not melt by itself. It needs to be in direct contact with NiTi for melting to occur, and a very significant amount of NiTi enters the eutectic melt as well. The eutectic liquid composition is fixed and is thought to be approximately 76 atom % (NiTi) and 24 atom % niobium and forms at 1170 C. For this reason, when joining NiTi alloys, it is undesirable to bring niobium in direct contact with the NiTi objects to be joined, because those same objects will be significantly attacked as the contact melting reaction proceeds.
Since direct contact is undesirable, the present invention provides a process to avoid such direct contact. The process brings niobium in contact with NiTi in a sacrificial structure that can contribute the (NiTi) atoms to the melt pool, but without damaging the underlying components to be joined. This is possible because once formed, the eutectic liquid flows hydraulically with great ease. Since this liquid is more than one third titanium atoms, which are very reactive, it readily dissolves surface oxides and wets completely virtually any metal surface. It flows with ease into capillary crevices and can thus fill them, bonding surfaces metallurgically, and doing so without the use of fluxes.
The present invention enables making strong metallurgical joints between extremely fine solid or hollow tubes, or other members. For these joints, only very small quantities of niobium are needed and may be supplied by any of a number of deposition or coating processes. The use of organic binders is precluded by the need to exclude contamination. Furthermore, such joints require some degree of reinforcement in order to be mechanically robust. The present invention uses a small cylindrical sleeve covering the joint region between the inner components, e.g., small tubes (hypotubes) or solid tubes or wires, to be joined, the sleeve coated with a controlled amount of niobium, and reactively brazed to the inner components as in the brazing technique disclosed in U.S. Pat. No. 7,896,222.
If the niobium for reactive brazing is deposited onto the inner tubes-to-be-joined before they are inserted into the sleeve, contact melting occurs between niobium and the tubes-to-be-joined, potentially weakening them.
Furthermore, in dealing with very small physical elements such as hypotubes, it could be difficult and expensive to apply such niobium, in the correct quantity, and at the correct location, to each of the individual objects (components) to be joined. That is, techniques for efficiently applying a niobium coating or film to small components such as by physical vapor deposition (PVD), are not easily performed. The present invention provides a simpler way to utilize NiTi and niobium to effect a joint between two components composed of nickel titanium alloy (nitinol-NixTiy), or between two NiTi components having different compositions, or between a NiTi alloy and another metal or metal alloy (e.g., biocompatible metal or metal alloy for medical applications). The processes can facilitate manufacture and reduce manufacturing costs.
It should be appreciated that the term melt or melting or melted as used throughout the application does not mean the entire sleeve (or coupler) needs to be turned into liquid but can also mean that only a portion of the sleeve (or coupler) turns into a liquid. Thus, less than the entire sleeve (or coupler) or the entire sleeve (or coupler) can turn into a liquid via melting using the methods and processes disclosed herein.
The present invention has application to construct surgical tools or other biomedical devices (or other non-medical devices), in which the special mechanical properties of superelastic nitinol (NiTi) alloys (SE NiTi) are combined with also-desired properties of shape-memory nitinol (SM NiTi) formulations, or of ductile stainless steel alloys or other metal alloys or metals. A biocompatible brazed joint can be made between NiTi alloy components if a small amount of pure niobium metal, in the joint region, enters into a contact-eutectic-melting reaction with the NiTi alloys in the joint. This invariant reaction produces a liquid with eutectic composition that is rich in titanium such that it flows readily on, and along, surfaces and into capillary spaces. When pure niobium reacts with a NiTi alloy, approximately two volumes of NiTi metal will enter the eutectic liquid for each volume of niobium in the reaction. Thus, if the location, form, and amount of added niobium metal are not carefully controlled, deleterious attack of the structures-to-be-joined can occur. Also, the capillary flow of the eutectic liquid must be managed properly, so that eutectic liquid metal flows to regions of the joint structure where it is needed for formation of the joint.
In the present invention, a carefully-controlled volume of pure niobium metal is applied or deposited (by any one of many possible physical deposition methods) to the outside diameter (outer surface) of a metal component, e.g., a wire or tube such as a thin-walled tube, that is designed to be used as a coupling sleeve for a brazed joint with another component or between two components such as wires or tubes, e.g., two hypodermic-gauge tubes, of dissimilar biomedical alloys. The sleeve can be composed of nitinol (nickel titanium alloy) material such as SM-495 or NDC's SE-508 material. The present invention utilizes an economical industrial method for batch niobium-coating of NiTi tubes to make a precursor material, and can also utilize laser micromachining of the individual sleeve-tubes to enhance their functionality during the joint assembly process, and during the subsequent thermal brazing process. The process enables joining for example components of the following material, however, it should be appreciated that the present invention is not limited to such materials:
The inner component has an end which is inserted into an opening in the outer component (the sleeve) to ultimately form a device having different properties along its length. In some embodiments by way of example, the device could be a guidewire or a hypotube formed to have different properties along its length. Thus, the first component can form a proximal section of the device and the second component can form a distal section of the device, and the ratio of the length of the inner component to the outer component can vary dependent on the desired length for the more rigid section of the device. Depending on the selected lengths, one of the components could also form an intermediate section of the device. For example, the second component can be composed of a material of less rigidity so that it can form a more flexible distal end of the device. In alternative embodiments, another component is inserted into another opening in the outer component (sleeve) at the end opposite the end the first component was inserted to form another device section. For guidewires, it is desirable to have the distal section the most flexible (less stiff) or the distal section more malleable or more formable than the proximal section. In other devices, it might be desirable to have the proximal section or an intermediate section most flexible (less stiff). It can be appreciated that by joining these materials using the processes of the present invention disclosed herein, varying properties can be provided along a length of the device. These include by way of example, varying stiffnesses, varying transition temperatures, varying dimensions (e.g., tapers), varying formability or malleability, varying radiopacity, varying structure such as tubes joined to braids, etc. Additionally, multiple joints can be provided so that the device can be formed of multiple components, with the niobium sleeve utilized to join the two adjacent components. Thus, it should be appreciated that one component can be joined to the sleeve, (e.g.,
Also, in alternate embodiments the sleeve can be bifurcated to have more than two open ends, e.g., have a Y-shape to receive three components, e.g., a component extending into each leg of the “Y”. Additionally, it is also contemplated that multiple components can be inserted into an end of the sleeve. For example, the “first component” and/or the “second component” can be a single component or multiple components inserted into an end of the sleeve. If multiple components, the components can be D-shaped (less than 360 degrees when viewed in transverse section) and preferably together form a full 360 degrees extending into the end of the sleeve. If not forming the 360 degrees, the sleeve shape preferably conforms to the shape (<360 degrees) of the combined inner components inserted in the end of the sleeve.
The present invention utilizes an economical industrial method for batch niobium-coating of NiTi tubes to make a precursor material, and can also utilize laser micromachining of the individual tubes (sleeves) to enhance their functionality during the joint assembly process, and during the subsequent thermal brazing process. In preferred embodiments, a continuous wave rather than a pulse wave is utilized for laser brazing. Also, in preferred embodiments, XYZ 3-Axis simultaneous scanning method is utilized rather than a fixed laser. Furnace brazing can be used to join very thick workpieces (thick samples require more power to heat) or in a batch process where multiple joints are brazed at one time (instead of laser brazing where typically one joint is created at a time). One advantage of laser brazing is that unlike furnace brazing, the entire device is not exposed to the brazing temperatures but just the joints. In some embodiments by way of example, laser brazing can be used for heating a solid wire of 0.040 inch diameter.
In one embodiment, the sleeve (outer component) is coated with niobium by a PVD process such as sputtering. Other deposition methods/techniques for applying niobium so it sticks to the outer surface of the sleeve, thereby providing a niobium coating or film (having a coating thickness), are also contemplated. These include by way of example pulsed laser deposition, vacuum evaporation, laser powder consolidation (as in 3D printing), plasma spray, thermal spray, kinetic spray (spraying fine local powders), laser cladding, etc. Tube co-extrusion could also be utilized. Preferably, the deposition process is applied to precursor nitinol stocks, such as nitinol sheets, wires, strips, tubes, etc., which are subsequently cut into the sleeves, or other joint-enabling structures, for joining two components, e.g., two tubes. After the deposition process, the nitinol stock is preferably laser cut to form the individual sleeves. During the individual sleeve cutting process, the laser can be also be utilized to cut other features into the sleeves such as fenestrations and/or slots, as discussed below. In some embodiments, the niobium is applied to the nitinol stock then the features (e.g., fenestrations or slots described below) are laser cut followed by laser cutting the stock into individual sleeves; in other embodiments, the features (e.g., fenestrations or slots) are laser cut in the nitinol stock then the niobium is applied to the stock followed by laser cutting the stock into individual sleeves; in other less preferred embodiments, the features (e.g., fenestrations or slots) are laser cut in the nitinol stock then the stock is laser cut into individual sleeves followed by applying niobium to individual sleeves. Other sequences of these steps are also contemplated.
The sleeve (also referred to herein as “the niobium-coated sleeve” or the “niobated sleeve”) can be used for joining two components. The sleeve is positioned over the two components to be joined (also referred to herein as the “inner components”), which can in some embodiments be in the form of two tubular components that are substantially longer than the sleeve. The niobium reacts with the NiTi alloy on the outer surface of the sleeve, to produce a eutectic liquid in the manner described in aforementioned U.S. Pat. No. 7,896,222 (the entire contents incorporated herein by reference). The eutectic liquid produced is typically about 3× the volume of the niobium that has reacted, and flows by capillary action on the surface of the sleeve, finding its way into the gap between the overlying sleeve (outer component) and the underlying inner components, i.e., the gap between the outer diameter of the inner components and the inner diameter of the outer component (sleeve). That is, the eutectic liquid flows over the ends (edges) of the sleeve (and or through holes in the sleeve) and through the space (gap) between the inner components and the sleeve, eventually filling this gap. When the assembly is quenched, this effects robust metallurgical attachment of the two components and applies reinforcement of the butt joint of the two components. Various embodiments of the sleeve are disclosed herein.
In some embodiments, the niobium-coated sleeve is configured so it that allows eutectic liquid to flow mainly through intermediate regions of the sleeve, i.e., regions spaced from its ends or edges (some flow can also be over the ends). This flow through the intermediate regions can be achieved by providing the sleeve with micromachined porosity, i.e., fenestrated zones through the wall of the sleeve, spaced from the two ends of the sleeve, as discussed below. In other embodiments, the eutectic liquid is channeled to flow only through these intermediate regions of the sleeve rather than through the intermediate regions and the ends. This is also described in more detail below.
The amount/level of niobium applied to the sleeve needs to be carefully predetermined to effect the desired joining of the components. One volume niobium, as noted above, reacts with approximately two volumes of NiTi alloy, to form a eutectic liquid having a total of three times the niobium volume. Consequently, if there is too much niobium on the sleeve, when heated, it can dissolve the whole structure. That is, an excess of niobium on the surface of the sleeve results in too much eutectic liquid being formed which can cause the destruction of the sleeve, and/or an unwanted erosive attack of the inner components. On the other hand, if there is too small an amount of niobium on the sleeve, an insufficient amount of eutectic liquid is formed that would not adequately fill the critical capillary spaces, such that a weak joint between the components would be formed. Therefore, the amount of niobium needs to be carefully optimized so the proper ratio of niobium coating to the sleeve, i.e., the PVD film or coating thickness on the sleeve surface, is applied.
For this ratio, let the optimum niobium coating thickness on the outer diameter of the sleeve be given as a fraction of the sleeve wall thickness, which is directly proportional to the volume ratio of coating to sleeve. Then if this ratio is greater than one half, the eutectic reaction would consume the whole of the sleeve, an undesired result. Therefore, in preferred embodiments, the desired ratio of coating thickness to sleeve wall thickness would be ≤½.
Additionally, the absolute thickness of the niobium coating or film that is required on the sleeve is related to the size of the gap between the sleeve and the inner component(s) to be joined, the gap defined as the space between the inner diameter of the sleeve and the outer diameter of the inner components to be joined (and referred to herein as the “sleeve-to-inner-component gap”). This gap is proportional to the amount of eutectic liquid needed to fill it. The volume of this gap may be taken as an absolute minimum volume of eutectic liquid needed, which should be corrected upwards for diversion of eutectic liquid to capillary sinks outside the gap. Therefore, if a gap of a given thickness is to be filled, in preferred embodiments, then a niobium coating of one half this thickness would provide enough eutectic liquid to fill this gap, with 50 percent to spare.
Consequently, the preferred niobium coating thickness on the outer diameter of the sleeve is between one half the sleeve wall thickness, at a maximum, and, at a minimum, one half the thickness of the sleeve-to-inner-component gap.
A refinement of the foregoing optimized ratios discussed above can be made taking into account how much unreacted nitinol sleeve is desired to remain, unreacted, at the joint, to function as a reinforcement. (After the brazing process, the now-brazed sleeve may be subjected to post-braze centerless grinding operations and other finishing protocols such as electropolishing).
In preferred embodiments, at minimum, the maximum thickness of the Nb layer is less than or equal to ½ the thickness of the wall of the sleeve. In more preferred embodiments, the maximum thickness of the Nb layer is less than or equal to ¼ the thickness of the wall of the sleeve Note in such embodiments, portions of the sleeve will be left behind and not dissolved into the eutectic liquid, creating a reinforcement. In other embodiments, for example, the niobium coating thickness is between about 1% and about 15% of the sleeve wall thickness, and in more particular embodiments between about 2% and about 10%, and in more particular embodiments between about 1.8% and about 9.2% of the sleeve wall thickness and in other more particular embodiments between about 2.9% to about 14.6%. (Note “about” as used herein can mean for a range of ±10% or a range of ±20% of the given percentage or given value/amount). Note the thickness of the niobium coating can be higher when joining solid components than when joining tube components since too much niobium could eat through the walls of the tubes due to their thinner walls. In some embodiments, the niobium by way of example has a thickness between 1 to 5 microns.
The required niobium coating thickness does not depend on the length of the sleeve because all of the volumes discussed above vary directly with this length, such that the ratios mentioned are not changed if the length of the sleeve is changed. However, the preferred length of the sleeve, in order for it to have ease of handling, and so that it acts as adequate reinforcement of the joint, is preferably ten times the outer diameter of the inner components, e.g., hypotubes, to be joined, but may for example be as little as five times, or for example as great as one hundred times this diameter. In any case, preferred sleeves for joining hypotube-gauge components will be only a few millimeters in length, and many individual sleeves may be mass produced from off-the-shelf nitinol hypotube stock. In the present invention, the niobium required to create a sufficient liquid volume to fill critical capillary spaces is applied to the outer surface of the sleeve material, in a batch process, in the knowledge that the liquid formed during the eutectic reaction (contact melting) will flow along surfaces and collect in the capillary spaces between the sleeve and tubes that constitute the reinforced metallurgical joint.
Referring now in detail to the drawings wherein like reference numerals identify similar or like components throughout the several views, the sleeves in preferred embodiments are manufactured from a plurality of long superelastic NiTi tubes having an inner diameter selected so that a close fit, e.g., a friction-fit, can be made between the sleeve and the inner components (e.g., tubes) to be joined. Preferably the inner diameter of the sleeve is 5-12 micrometers greater than the outer diameter of the inner components (e.g., tubes) to be joined, although other dimensions are also contemplated. A plurality of these tubes, each long enough to be later cut into multiple individual laser-cut sleeves, are preferably niobium coated in a single deposition batch before being cut into separate tubes (sleeves).
The tubes 12 may positioned side by side, e.g., their longitudinal axes are parallel, and attached to adjacent tubes forming a row of parallel tubes 12. These tubes 12 could then be coated by sputter deposition of pure niobium on both sides. Other deposition methods can alternatively be utilized. Various arrangements of the plurality of tubes are contemplated. For example, the tubes 12 could be fixed in a line (parallel) as shown in
The advantage of the batches is that multiple tubes can be niobium coated from the stock. This reduces the manufacturing costs since multiple tubes can be formed at one time. Additionally, since the tubes are initially part of an attached set, it facilitates forming of the tubes since it avoids the difficulties involved with handling of the small tubes if they were individual units. Once niobated (or before niobated in some embodiments), the tubes can be laser cut to provide features such as slots, holes, etc., as described herein. In preferred embodiments, only after these laser cut modifications are complete are the niobated tubes finally laser cut into individual tubes for use as the individual sleeves described herein. The final dicing can in some embodiments occur at the time of mechanical assembly of the joint.
It should be appreciated that although not preferred, in some embodiments of the present invention, the sleeves can be niobated after cut into individual tubes.
The tubes of the set can be of desired length for intended applications and in some embodiments by way of example are each about 3 inches to about 4 inches, although other lengths are contemplated. (As noted above, the tubes can also be cut to this desired length from a longer tube). In the embodiment of
In one embodiment by way of example, sleeves meant for joining two hypodermic-scale tubular components that are each of a length of several tens of centimeters and a diameter of about 0.4 millimeters, are made from a batch of tubes 12 which are small superelastic NiTi tubes and each have a length of about 4 inches and a diameter of about 0.020 inches, with inside diameters as described herein. The tubes can then be separated, i.e., laser cut, from the batch after application of niobium if a solid tube is desired, or alternatively, separated after application of niobium and laser micromachined to add features such as fenestrations, slots, etc. Note tubes of different lengths and diameters (which form the outer sleeve) are also contemplated, depending on the components to be joined. Note the foregoing processes can be utilized for tubular components with a lumen or solid components.
Various alternate embodiments of the niobium-coated sleeve will now be discussed. In the embodiment of
In an alternate embodiment, the niobium-coated sleeve has micro fenestrations for entry of eutectic liquid through intermediate portions of the outer surface (wall) of the sleeve. As shown in the embodiment of
In one example, a fenestrated sleeve having a length between about 3 mm to about 5 mm is placed over two different NiTi alloy tubes to be joined. The sleeve has an outer diameter of 0.0185 inches and an inner diameter of 0.0145 inches. The wall thickness is therefore 0.002 inches. The fenestrations extend though the entire wall thickness and are of a diameter of between 0.0005-0.001 inches. When heated the eutectic liquid flows through the fenestrations as well as around the ends of the sleeve.
Although vacuum furnace heating can be used to initiate the eutectic melting event, preferably laser irradiation is utilized to selectively heat the sleeve without excessively heating the inner objects (components) to be joined. The embodiment shown in
Below are charts showing two examples of dimensions of the sleeve 160, with the dimensions/areas demarcated in
In Example 2, all dimensions are the same as Example 1 except the following
In an alternate embodiment (Example 4), the dimensions can be the same as Example 3 except the ID of the sleeve is 0.0122 inches and the strut width is 0.0164 inches.
In the embodiment of
In the foregoing embodiments, the sleeves are placed over the components, e.g., the two inner (e.g., tubular or solid (e.g., wire)) components to be joined, and initially held by a friction fit. In alternate embodiments, the sleeve is provided with a gripping or retention feature to enhance retention of the internal components during processing. Such gripping/retention feature can be utilized with any of the sleeves disclosed herein, e.g., the solid sleeve, fenestrated sleeve, slotted sleeve etc. This provides for additional gripping of the inner wires or tubes, e.g., hypotubes, for ease of handling at the time of assembly/manufacture.
In the alternate embodiment of
In
In the foregoing embodiments, circular (or oval) or semi-circular (or semi-oval) sleeves are described to join circular (or oval) or semi-circular (or semi-oval) components. For such joining, circular (or oval) or semi-circular (or semi-oval) sleeves are placed over the components to be joined, preferably fully, but at least partially or substantially, surrounding the outer surface adjacent the abutting end.
It is also contemplated that the planar component 90 can be used to join components that are not planar, e.g., tubular or have curved surfaces. This would provide a flexible joint since the components would not be joined around the full circumference.
The foregoing embodiments illustrate use of the niobium-coated sleeve to attach two components end-to-end, i.e., forming a butt joint. However, the niobated sleeve concept disclosed herein can also be utilized in alternate embodiments to attach an outer component over a single inner component. For example, as illustrated in
In the embodiments described above, the components are joined end to end, forming a rigid joint between the two components so the two components are fixed with respect to each other. In the embodiment of
In the embodiment of
In the embodiment of
The braids of
The foregoing embodiments utilize niobated sleeves to attached components, with the component inserted inside the sleeve. In the alternate embodiments of
Various geometries of the niobated coupler bead can be utilized and several examples of the geometry are illustrated. These geometries are provided by way of example as other shaped edges are also contemplated to provide complementary shaped ends/edges. Preferably the edges/sides are non-linear to increase the contact surface area and aid in axial alignment. Note the components to be joined illustrated in
In
It should be appreciated that the niobated coupler bead, like the niobated sleeve, can be used to attach to a single component.
In the foregoing embodiments, a sleeve is placed over the two components or a coupler is placed in axial alignment interposed between the two components. In the alternate embodiment of
With the description above, it can be appreciated how devices of different properties and/or different materials can be joined by the niobated sleeve.
Another embodiment of the guidewire is illustrated in
L1=180 cm
L2=142 cm
L3=25 cm
L4=7 cm
L5=10 cm
In the embodiment of
In an alternate embodiment, instead of the three segments, the guidewire can be formed from four sections: the proximal section (region) which has an Af=−15° C.; the adjacent intermediate section (region) which has an Af=20° C.; the adjacent distal section (region) which has an Af=45° C., and a distalmost section (region) can also have an Af=45° C. which form the very distal tip of the instrument. Stated another way, this embodiment differs from the embodiment of
It should be appreciated that the lengths L1-L10, along with other dimensions disclosed herein, are provided by way of example as other dimensions, e.g., lengths, are also contemplated.
Various diameters are also contemplated for the guidewires. For example, an outer diameter of 0.014 inches can be utilized. Additionally, a hydrophilic coating can be provided along a length of the guidewire. For example, in a guidewire having an overall length of 200 cm or 300 cm, an hydrophilic coating can extend along a length of 46 cm. Additionally, a radiopaque region for imaging can be provided along a length of the guidewire. For example, in a guidewire having an overall length of 200 cm or 300 cm, radiopaque can extend along a length of 10 cm. The distal flex zone of guidewire can extend for example a length of 20 cm or a length of 30 cm in guidewire having a length of 2200 cm or 300 cm. It should be understood that these dimensions/lengths are provided by way of example as other lengths are also contemplated. For example, the radiopaque length and hydrophilic coating can be longer or shorter than listed above.
As can be appreciated, the guidewires of
The system includes a control box having a stiffness changing button 202. Button 202 is operable to increase the stiffiiess of the device by applying heat to selected regions of the device. Wires extend from the box through the device into contact with the electrical contacts (heating elements. e.g., heating coils) 206 on the device to heat select contacts and regions. The number of contacts can vary and preferably insulation is provided between contacts. A wire lock button 208 is actuable to clamp the wire within the box 200 to maintain the wire on position. The wire lock button can in some embodiments be spring loaded and in a normally clamped (closed) position wherein it is released for wire insertion. The various sections/regions of the device can be electrically heated during insertion to adjust the stiffness during insertion or during use. After insertion, the device can be detached from the control box 200. Note cold fluid can be injected to cool regions of the device to reduce the stiffness of the desired regions.
As can be appreciated, use of the sleeve (collar) with a niobium coating or film creates a reinforced butt joint for two axially positioned (end to end) components and a reinforced joint for two coaxially positioned components (joining an outer component to an inner component). The sleeves with a niobium coating or film can also join two axially spaced components to create a connector or bridge between the two components. The components to be joined can be of different lengths. Configurations of the sleeves, e.g., laser cut holes, enable control/direction of eutectic liquid flow to form the reinforced metallurgical joint.
The metallurgical joining of components by the aforedescribed reactive eutectic brazing using niobated sleeves enables joining of superelastic material to superelastic material, shape memory material to shape memory material, shape memory material to superelastic material and stainless steel, tantalum or platinum to superelastic material or to shape material. The attachment to stainless steel for example can provide a super stiff component or alternatively a malleable material, depending on the stainless steel. The joining of components disclosed herein enables not only joining of components of different materials, but components of the same or different material having different properties to form for example a single tube with varying properties along its length, such as a stiffer portion at one end and a more flexible portion at another end, an enhanced radiopaque region at one end, a different diameter at one end, etc. The embodiments wherein the niobated sleeve forms a connector for the two axially spaced longitudinally aligned components provide a device such as an elongated tube with a flexible joint wherein one end of the device is flexible or bendable or otherwise movable with respect to the other end.
The components joined herein can be used for creating medical devices such as guidewires, stents, microcatheters, etc.; however, it also has application outside the medical device area where it is desired to join two components.
The present invention provides a) a method of forming the devices using the niobium sleeve process described herein; b) a device having regions of different properties and a joint formed by a niobium coated nickel titanium alloy sleeve melted thereon; and/or c) a device formed by the process of joining separate components together by a niobium coated nickel-titanium alloy sleeve melted onto the components to form a joint(s).
The present invention can also provide a) a method of forming the devices using the niobium coupler, e.g., a coupler bead in alignment with the components, and process described herein; b) a device having regions of different properties and a joint formed by a niobium coated nickel titanium alloy coupler melted thereon; and/or c) a device formed by the process of joining separate components together by a niobium coated nickel-titanium alloy coupler melted onto the components to form a joint(s).
The present invention can also provide a) a method of forming the devices using the process described herein for joining niobated ends of two components; b) a device having regions of different properties and a joint formed by melting niobium coated nickel titanium alloy ends of two components; and/or c) a device formed by the process of joining separate components together by melting of niobium coated nickel-titanium alloy ends of the components to form a joint(s).
While the above description contains many specifics, those specifics should not be construed as limitations on the scope of the disclosure, but merely as exemplifications of preferred embodiments thereof. Those skilled in the art will envision many other possible variations that are within the scope and spirit of the disclosure as defined by the claims.
This application claims priority from provisional application Ser. No. 62/791,693, filed Jan. 11, 2019 and is a continuation in part of application Ser. No. 16/271,593, filed Feb. 8, 2019, which claims priority from provisional application 62/631,867, filed Feb. 18, 2018, and from provisional application No. 62/791,693, filed Jan. 11, 2019. The entire contents of each of these applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62791693 | Jan 2019 | US | |
| 62631867 | Feb 2018 | US | |
| 62791693 | Jan 2019 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16271593 | Feb 2019 | US |
| Child | 16728183 | US |
