Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10 and Rule 13)

1. TITLE OF THE INVENTION:
METHOD TO FABRICATE A ROTATIONAL THROMBECTOMY WIRE

2. APPLICANT:
Meril Life Sciences Pvt. Ltd., an Indian company of the Survey No. 135/139 Bilakhia House, Muktanand Marg, Chala, Vapi-Gujarat 396191, India.

The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF INVENTION
[001] The present invention relates to a thrombectomy wire. More specifically, the present invention relates to a method for fabricating a thrombectomy wire.
BACKGROUND OF INVENTION
[002] Calcification of tissues, blood thickening and/or clumps may lead to formation of blood clots in blood vessels which block blood flow. This can cause damage to nearby tissues/organs and can be life-threatening. Some of the most common organs for blood clots to occur are legs, arms, intestines, brain, lungs and heart.
[003] Thrombectomy corresponds to removing blood clot or thrombus from within a blood vessel to help restore blood flow through the said vessel. During a surgical thrombectomy procedure, an incision into a blood vessel is made. A thrombectomy wire (which are generally sinusoidal in shape) is inserted through the incision and rotated within the affected blood vessel at the position of the thrombus, effectively breaking up the vascular thrombus or other obstructive material. The thrombus particles are removed, and the blood vessel is repaired. This restores blood flow.
[004] The fabrication of the wire involves a complex methodology. Initially, a core wire is completely wrapped with a coiled wire. The coiled wire prevents treatment of the underlying core wire thus leading to corrosion of the core wire. Further, during the manufacturing process, fracture (or weakening) might occur at the welded joints between the coiled wire and the core wire as the welded joints are directly exposed to high temperature during the heat setting steps.
[005] Moreover, the coiled wire shields the core wire from adequate heat exposure thus leading to poor shape profile of the core wire. This in turn requires more time and effort during the shape setting process.
[006] Also, as shape setting is performed on the assembly of the coiled wire and core wire, it might lead to surface adulteration, as the micro contaminant of the heating bed could get inside the gaps of coiled wire and make the process of surface cleaning more tedious.
[007] Hence, there arises a need for a new fabrication technique of a thrombectomy wire which overcomes these challenges associated with the conventional wires.
SUMMARY OF INVENTION
[008] The present invention relates to a method to fabricate a wire. An elongate member is passed between a plurality of rollers. A distal portion of the elongate member is subjected to a pre-defined temperature ranging from 500 °C to 550 °C for a pre-defined time period ranging from 2 minutes to 8 minutes. The distal portion of the elongate member is treated with at least one acid at a pre-defined temperature ranging from 50 °C to 100 °C for a pre-defined time period ranging from 10 minutes to 30 minutes. The acid being one of nitric acid, phosphoric acid, and citric acid. A coiled member is slid over at least the distal portion of the treated elongate member. The coiled member includes a pitch and an outer diameter equal to the pitch. The ends of the coiled member are coupled to at least the distal portion of the treated elongate member.
[009] The foregoing features and other features as well as the advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.
BRIEF DESCRIPTION OF DRAWINGS
[0010] The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the apportioned drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those in the art will understand that the drawings are not to scale.
[0011] Fig. 1 depicts a wire 100 in accordance with an embodiment of the present disclosure.
[0012] Fig. 1a depicts a distal portion of the wire 100 in accordance with an embodiment of the present disclosure.
[0013] Fig. 2 depicts a method 200 to fabricate the wire 100 in accordance with an embodiment of the present disclosure.
[0014] Figs. 2a-i depict various stages of the method 200 in accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION OF ACCOMPANYING DRAWINGS
[0015] Prior to describing the invention in detail, definitions of certain words or phrases used throughout this patent document will be defined: the terms "include" and "comprise", as well as derivatives thereof, mean inclusion without limitation; the term "or" is inclusive, meaning and/or; the phrases "coupled with" and "associated therewith", as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have a property of, or the like; Definitions of certain words and phrases are provided throughout this patent document, and those of ordinary skill in the art will understand that such definitions apply in many, if not most, instances to prior as well as future uses of such defined words and phrases.
[0016] Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment, but mean “one or more but not all “embodiments” unless expressly specified otherwise. The terms “including,” “comprising,” “having,” and variations thereof mean “including but not limited to” unless expressly specified otherwise. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. The terms “a,” “an,” and “the” also refer to “one or more” unless expressly specified otherwise.
[0017] Although the operations of exemplary embodiments of the disclosed method may be described in a particular, sequential order for convenient presentation, it should be understood that the disclosed embodiments can encompass an order of operations other than the particular, sequential order disclosed. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Further, descriptions and disclosures provided in association with one particular embodiment are not limited to that embodiment, and may be applied to any embodiment disclosed herein. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed system, method, and apparatus can be used in combination with other systems, methods, and apparatuses.
[0018] Furthermore, the described features, advantages, and characteristics of the embodiments may be combined in any suitable manner. One skilled in the relevant art will recognize that the embodiments may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments. These features and advantages of the embodiments will become more fully apparent from the following description and apportioned claims, or may be learned by the practice of embodiments as set forth hereinafter.
[0019] The present disclosure proposes a method to fabricate a thrombectomy wire (or wire). The wire is used to break up vascular thrombus or other obstructive material into smaller pieces to restore vascular blood flow.
[0020] The wire of the present disclosure includes a coiled member wrapped around an elongate member. Before wrapping the coiled member around the elongate member, the elongate member is subjected to a heat setting process and a chemical passivation process. Due to the absence of the coiled member over the elongate member during the heat setting process, the elongate member is efficiently heat set using less time and effort. Further, due to the absence of the coiled member over the elongate member during the chemical passivation process, the elongate member is efficiently passivated to prevent its corrosion. Furthermore, since only a distal portion (having, for example, a sinusoidal shape) of the elongate member is subjected to the heat setting process, the entire wire is not required to be subjected to any surface cleaning process. Only the distal portion of the elongate member is required to be surface cleaned thus, saving time and resource while fabricating the wire.
[0021] And only after the distal portion of the elongate member is subjected to the heat setting process, the coiled member is coupled to the elongated member via dome shape welds. Effectively, the dome shaped welds are not subjected to high temperatures thus, the physical integrity of the dome shaped welds is preserved.
[0022] Fig. 1 illustrates an exemplary embodiment of a wire 100 of the present disclosure. The wire 100 includes an elongate member 110, a coiled member 130 (as shown in Fig. 1a) and a tubular member 150.
[0023] The elongate member 110 is disposed at a distal end 100a of the wire 100. The elongate member 110 is made of a material including, but not limited to, nitinol, stainless steel (S.S.), elastomers, titanium, nickel, rubbers, polyurethanes, etc. In an exemplary embodiment, the elongate member 110 is made of nitinol.
[0024] A distal portion of the elongate member 110, as shown in Fig. 1a, may include a pre-defined shape including, but not limited to, straight, sinusoidal, angled tip (ranging from 40 degrees to 90 degrees), J tip, spiral shaped, tapered helix shaped, elliptical shaped, dome shaped, etc.
[0025] In an exemplary embodiment, the distal portion of the elongate member 110 is toggled between a straight configuration and a sinusoidal configuration. In the straight configuration, the elongate member 110 (and the wire 100) is constrained within a sheath (for example, a catheter or the like) for navigating through the tortuous vasculature. Once the wire 100 is positioned at a treatment site, the distal portion of the elongate member 110 is revealed from within the sheath. Upon revelation of the elongate member 110, the distal portion of the elongate member 110 automatically assumes its sinusoidal configuration (as shown in Fig. 1). The sinusoidal configuration of the elongate member 110 helps to break the blood clots/thrombus more efficiently and effectively from the tortuous artery or veins covering the complete periphery of the blood vessel.
[0026] The elongate member 110 may include a pre-defined length ranging from 400 mm to 4500 mm. The elongate member 110 may have a diameter ranging from 0.0047 inches (0.12 mm) to 0.039 inches (1 mm). In an exemplary embodiment, the length and diameter of the elongate member 110 is 1350 mm and 0.0098 inches (0.25 mm), respectively.
[0027] Alternatively, the elongate member 110 may include a tapered profile, i.e., the diameter of the elongate member 110 may vary along at least a portion of its length. In an exemplary embodiment, the distal portion of the elongate member 110 is tapered. The tapered distal portion of the elongate member 110 helps to increase the flexibility of the distal portion thus, providing easy trackability of the wire 100 in tortuous blood vessels. Further, the tapered profile of the distal portion of the elongate member 110 helps to maintain adequate shape (for example, sinusoidal shape) during the heat (shape) setting process.
[0028] The distal portion of the elongate member 110 may have a length ranging from 30 mm to 80 mm. In an exemplary embodiment, the length of the distal portion of the elongate member 110 is 40 mm. The maximum diameter of the distal portion of the elongate member 110 may range from 0.0047 inches (0.12 mm) to 0.039 inches (1 mm). The minimum diameter of the distal portion of the elongate member 110 may range from 0.0012 inches (0.03 mm) to 0.0078 inches (0.2 mm). The distal portion of the elongate member 110 has the minimum diameter at the distal end 100a. In an exemplary embodiment, the diameter of the distal portion of the elongate member 110 tapers from 0.69 mm to 0.18 mm. The tapering of the distal portion of the elongate member 110 may be uniform or non-uniform.
[0029] The coiled member 130 may be wrapped at least partially around the length of the elongate member 110. In an exemplary embodiment, the coiled member 130 is wrapped around the entire length of the elongate member 110.
[0030] After the coiled member 130 is wrapped around the elongate member 110, an outer diameter of the coiled member 130 (and the wire 100) ranges from 0.2 mm to 2 mm. In an exemplary embodiment, the outer diameter of the wire 100 is 1.12 mm.
[0031] The ends of the coiled member 130 may be coupled to the elongate member 110 via laser welding, spot welding, plasma arc welding, soldering, brazing, adhesives (such as ultraviolet curing adhesives), etc. In an exemplary embodiment, the ends of the coiled member 130 are coupled to the elongate member 110 by creating dome shaped welds using a laser welding technique. The dome shape welds help to improve the passage of the wire 100 through the tortuous blood vessels without afflicting any injury to the inner wall of the blood vessel. The dome shape welds eliminate any surface roughness at the junction between the elongate member 110 and coiled member 130. Further, the dome shape welds provide a comparatively good amount of strength at the junction between the elongate member 110 and coiled member 130.
[0032] The coiled member 130 may be made of a material including, but not limited to, nitinol, stainless steel (S.S.), platinum, titanium, etc. In an exemplary embodiment, the coiled member 130 is made by wounding a stainless steel (S.S.) cable. The cable may have a diameter ranging from 0.04 mm to 0.5 mm. In an exemplary embodiment, the diameter of the cable is 0.44 mm.
[0033] The coiled member 130 may define a pre-defined pitch ranging from 0.04 mm to 0.5 mm. In an exemplary embodiment, the pitch of the coiled member 130 is equal to the diameter of the cable, thus providing a close and tight pitch.
[0034] Although the elongate member 110 and the cable of the coiled member 130 are described to have a circular cross-section, cross section of other shapes is also within the scope of the teachings of the present disclosure.
[0035] The tubular member 150 is disposed at a proximal end 100b of the wire 100. In an exemplary embodiment, the tubular member (150) is coupled to a proximal portion of the elongate member 110 wrapped with the coiled member 130. The tubular member 150 may be made of a material including, but not limited to, stainless steel, nitinol, platinum, titanium, mild steel, etc. In an exemplary embodiment, the tubular member 150 is made of stainless steel. The tubular member 150 may either be hollow or solid. In an exemplary embodiment, the tubular member 150 is hollow. The tubular member 150 helps to support the elongate member 110 and transfer adequate torque to the entire elongate member 110.
[0036] The tubular member 150 may include a uniform configuration, a tapered configuration or a stepped configuration. In the uniform configuration, the tubular member 150 includes a uniform diameter throughout its length. In the tapered configuration, the tubular member 150 includes either a gradual decrease or increase in the diameter across its length. In the stepped configuration, the tubular member 150 includes one or more portions having distinct diameters.
[0037] In an exemplary embodiment, as shown on Fig. 1, the tubular member 150 includes a thick portion 150a towards the proximal end 100b and a thin portion 150b towards the distal end 100a. Thus, the elongate member 110 resembles to have a stepped configuration. The stepped configuration of the tubular member 150 helps to provide the necessary amount of strength and torque to efficiently rotate the elongate member 110. Further, the tubular member 150 gives good pushability to the wire 100.
[0038] The thick portion 150a of the tubular member 150 may include a length ranging from 15 mm to 30 mm. The thick portion 150a may include an outer diameter ranging from 2.2 mm to 3.2 mm. The thick portion 150a may include an inner diameter ranging from 1.3 mm to 2 mm. In an exemplary embodiment, the length, outer and inner diameter of the thick portion 150a are 20 mm, 2.4 mm and 1.74 mm, respectively.
[0039] The thin portion 150b of the tubular member 150 may include a length ranging from 180 mm to 220 mm. The thin portion 150b may include an outer diameter ranging from 1.25 mm to 1.8 mm. The thin portion 150b may include an inner diameter ranging from 1 mm to 1.2 mm. In an exemplary embodiment, the length, outer and inner diameter of the thin portion 150b are 200 mm, 1.6 mm and 1.3 mm, respectively.
[0040] In an exemplary embodiment, the thick portion 150a of the tubular member 150 encloses a proximal portion of the thin portion 150b of the tubular member 150. In an alternate embodiment, the thick portion 150a and the thin portion 150b form an integral structure.
[0041] Fig. 2 depicts an exemplary method 200 to fabricate the wire 100. The method 200 helps to preserve the physical properties of the material used to manufacture the wire 100 as well as helps to increase the longevity of the wire 100.
[0042] The method 200 commences at step 201 by subjecting the elongate member 110 to a straightening process. In an exemplary embodiment, as shown in Fig. 2a, a spool of nitinol wire is subjected to straightening by passing the elongate member 110 between a plurality of rollers 201a. The rollers 201a are disposed above and below the elongate member 110, thus defining a gap. The gap may have a height corresponding to the diameter of the elongate member 110.
[0043] The rollers 201a may have shape including but not limited to cylindrical rollers, guide roller (with groovy shape), semi-circle type rollers, etc. The rollers 201a may be systematically spaced to prevent uneven distribution of load. The rollers 201a may have a diameter ranging from 20 mm to 50 mm. The rollers 201a may rotate at a pre-defined speed of more than 10 RPM and up to 50 RPM based upon requirement. In an exemplary embodiment, the diameter of the cylindrically shaped rollers 201a are 30 mm which rotate at a speed of 30 RPM. In an alternate embodiment, some of the cylindrically shaped rollers 201a include different diameters ranging from 20 mm to 50 mm. The rotation of the rollers 201a helps the elongate member 110 to move linearly with respect to the rollers 201a. Once the elongate member 110 traverses between the rollers 201a, the elongate member 110 assumes a straight shape.
[0044] At step 203, the elongate member 110 is cut to its pre-defined length ‘L’ (as shown in Fig. 2b). In an exemplary embodiment, the elongate member 110 is cut using a slicing machine (not shown). Alternatively, the elongate member 110 may be cut to its length ‘L’ using at least one of a hand plier, a portable or machine grinder, a wire cutter, etc.
[0045] At step 205, at least a portion of the elongate member 110 is subjected to a grinding and deburring process. In an exemplary embodiment, the distal portion of the elongate member 110 is subjected to the grinding and deburring process. The grinding and deburring process helps to provide the tapering profile (as shown in Figs. 2c and 2d) to the distal portion of the elongate member 110 (as described above). In an exemplary embodiment, a cylindrical grinding wheel is used to grind and deburr the distal portion of the elongate member 110. Alternatively, at least one of a laser grinder, a pulley operated belt grinder, etc. is used to grind and deburr the distal portion of the elongate member 110.
[0046] At step 207, the elongate member 110 is kept inside a mold 207a. Thereafter, at least a portion of the elongate member 110 is subjected to a heat setting process. The mold 207a may be made of a material including, but not limited to, stainless steel (SS), acrylonitrile butadiene styrene (ABS), high density polyethylene (HDPE), polycarbonate (PC). In an exemplary embodiment, the mold 207a is made of stainless steel (SS). In an alternate embodiment, the mold 207a is made by stereolithography (SLA). The mold 207a may include one or more tubular structures 207b arranged in a pre-defined pattern. The pre-defined pattern corresponds to the shape of the distal portion of the elongate member 110. In an exemplary embodiment, as shown in Figs. 2e and 2e1, the tubular structures 207b are arranged in the shape of sinusoidal curve. The distal portion of the elongate member 110 is inserted through the tubular structures 207b and clamped with respect to the mold 207a to shape the distal portion of the elongate member 110 corresponding to the pre-defined pattern of the tubular structures 207b.
[0047] Alternatively, a mold (not shown) is provided with a cavity having a pre-defined shape. The pre-defined shape corresponds to the shape of the distal portion of the elongate member 110. In an exemplary embodiment, not shown, a mold is provided with a sinusoidal shaped cavity. The distal portion of the elongate member 110 is inserted into the cavity and clamped with respect to the mold to shape the distal portion of the elongate member 110 corresponding to the pre-defined shape of the cavity.
[0048] The mold 207a along with the distal portion of the elongate member 110 disposed within the tubular structures 207b of the mold 207a is subjected to a pre-defined temperature for a pre-defined time period. The pre-defined temperature ranges from 500 °C to 550 °C. The pre-defined time period ranges from 2 minutes to 8 minutes. In an exemplary embodiment, the mold 207a along with the elongate member 110 is submerged in an industrial fluidized bed (also known as heat/shape setting machine) at a temperature of 505°C for 5 minutes. As shown in Fig. 2f, subjecting the elongate member 110 to the pre-defined temperature for the pre-defined time period helps the elongate member 110 to acquire the shape defined by the tubular structures 207b of the mold 207a.
[0049] After the pre-defined time period passes, the elongate member 110 is recovered from the mold 207a and quenched to the room temperature. The quenching of the elongate member 110 relieves internal stress and improves properties such as, without limitation, the durability, ductility, toughness, and elasticity of the elongate member 110.
[0050] At step 209, the elongate member 110 is subjected to a chemical passivation process. In an exemplary embodiment, only the distal portion of the elongate member 110 is subjected to the chemical passivation process. In an alternate embodiment, the entire length of the elongate member 110 is subjected to the chemical passivation process. The chemical passivation process provides corrosive resistance property to the elongate member 110 as well as improves its biocompatibility. Further, the chemical passivation process helps to remove impurities from the surface of the elongate member 110 thus, helping to provide uniform and smooth surface.
[0051] In the chemical passivation process, the elongate member 110 (or a portion thereof) is treated with at least one acid at a pre-defined temperature for a pre-defined time period. The acid may be selected from a group including, but not limited to, nitric acid, phosphoric acid, citric acid, etc. The pre-defined temperature ranges from 50 °C to 100 °C. The pre-defined time period ranges from 10 minutes to 30 minutes. In an exemplary embodiment, the distal portion of the elongate member 110 is subjected to 20% nitric acid at 80°C for 20 mins.
[0052] At step 211, the coiled member 130 is prepared. The coiled member 130 is prepared with the help of a mandrel 211a. The mandrel 211a may have a shape corresponding to the elongate member 110. The mandrel 211a ensures precise dimensional profile of the coiled member 130 (for example, the pitch and the outer diameter of the coiled member 130).
[0053] The cable (as described above) is wound around the mandrel 211a in a pre-defined pitch (as described above) to obtain the coiled member 130. While winding the cable around the mandrel 211a, either one of the cable or the mandrel 211a is rotated in a pre-defined direction to obtain the coiled member 130. In an exemplary embodiment, as shown in Fig. 2g, the mandrel 211a is rotated in clockwise direction to wind the cable around the mandrel 211a. Once the cable is wound around the mandrel 211a, the coiled member 130 is recovered from the mandrel 211a.
[0054] At step 213, as shown in Fig. 2h, the coiled member 130 is slid over at least a distal portion of the treated elongate member 110 (as obtained from step 209). In an exemplary embodiment, the coiled member 130 is slid over the entire length ‘L’ of the elongate member 110. In an alternate embodiment, the coiled member 130 is slid over the distal portion of the elongate member 110 only.
[0055] At step 215, the ends of the coiled member 130 are coupled to at least the distal portion of the treated elongate member 110 to secure the coiled member 130 to the elongate member 110. The coiled member 130 is coupled to the elongate member 110 via laser welding, spot welding, plasma arc welding, soldering, brazing, adhesives (such as ultraviolet curing adhesives), etc. In an exemplary embodiment, as shown in Fig. 2i, the ends of the coiled member 130 are coupled to the elongate member 110 by creating dome shaped welds 130a at both the ends of the coiled member 130. The dome shaped weld 130a help to improve the passage of the wire 100 through the tortuous blood vessels without afflicting any injury to the inner wall of the blood vessel. The dome shape welds 130a eliminate any surface roughness at the junction between the elongate member 110 and coiled member 130. Further, the dome shape welds 130a provide a comparatively good amount of strength at the junction between the elongate member 110 and coiled member 130.
[0056] At step 217, the tubular member 150 is coupled towards a proximal portion of the assembly of the elongate member 110 and the coiled member 130. The tubular member 150 is coupled to the assembly of the elongate member 110 and the coiled member 130 via spot welding, plasma arc welding, etc. In an exemplary embodiment, the thin portion 150b of the tubular member 150 is coupled to a proximal portion of the assembly of the elongate member 110 and the coiled member 130 by spot welding. The tubular member 150 helps to support the elongate member 110 to transfer adequate torque to the entire elongate member 110.
[0057] Example 1 (Prior art): A method to prepare a conventional thrombectomy wire
[0058] A cable was coiled over an entire length of a core wire to form the thrombectomy wire. The ends of the cable, after coiling, was welded to the core wire. The thrombectomy wire was chemically passivated. A distal portion of the thrombectomy wire was subjected to a heat setting process to impart a sinusoidal shape to the thrombectomy wire.
[0059] It was observed that the core wire was susceptible to corrosion as the core wire was not efficiently chemically passivated. The welds between the core wire and the coiled cable were weakened due to the heat setting process. Further, the coiled cable shielded the core wire from high temperature during the heat setting process which led to inefficient heat setting process (took more time and consumed more resources). Further, during the heat setting process, the coiled cable was adulterated with micro-containments (for example, from the heating bed). Therefore, the thrombectomy wire was subjected to a tedious surface cleaning process.
[0060] Example 2 (Present disclosure): A method to prepare the wire 100 of the present invention
[0061] A spool of nitinol wire was subjected to straightening by passing the elongate member 110 between the plurality of rollers 201a. The elongate member 110 was cut to a length ‘L’ of 1350 mm using a slicing machine. The distal portion of the elongate member 110 was subjected to the grinding and deburring process. The distal portion of the elongate member 110 was inserted through the tubular structures 207b and clamped with respect to the mold 207a. The mold 207a along with the distal portion of the elongate member 110 disposed within the tubular structures 207b of the mold 207a was submerged in an industrial fluidized bed at a temperature of 505°C for 5 minutes. The elongate member 110 was recovered from the mold 207a and quenched to the room temperature. Thereafter, the distal portion of the elongate member 110 was chemically passivated using 20% nitric acid at 80°C for 20 mins.
[0062] A cable was wound around the mandrel 211a in a tight pitch to obtain the coiled member 130. The coiled member 130 was recovered from the mandrel 211a and was slid over the entire length ‘L’ of the elongate member 110. The ends of the coiled member 130 were coupled to the elongate member 110 by creating dome shaped welds 130a at both the ends of the coiled member 130. The tubular member 150 was coupled towards the proximal portion of the assembly of the elongate member 110 and the coiled member 130.
[0063] Since only the distal portion of the elongate member 110 was subjected to the heat setting process, the elongate member 110 was easily cleaned and chemically passivated (without any hindrance) to prevent corrosion. The elongate member 110 made of nitinol was efficiently shape set using the heat setting process because of the absence of the coiled member 130 over the elongate member 110 during the heat setting process. Further, the structural integrity of the dome shaped welds 130a was preserved as the welds were introduced after the heat setting process of the elongate member 110. Moreover, since distal portion of the elongate member 110 was heat set alone without the coiled member 130, there was no requirement for a tedious cleaning process.
[0064] The scope of the invention is only limited by the appended patent claims. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. , Claims:We claim,
1. A method (200) to fabricate a wire (100) comprising the following steps:
a. passing an elongate member (110) between a plurality of rollers (201a);
b. subjecting a distal portion of the elongate member (110) to a pre-defined temperature ranging from 500°C to 550°C for a pre-defined time period ranging from 2 minutes to 8 minutes;
c. treating the distal portion of the elongate member (110) with at least one acid at a pre-defined temperature ranging from 50°C to 100°C for a pre-defined time period ranging from 10 minutes to 30 minutes, the acid being one of nitric acid, phosphoric acid, and citric acid;
d. sliding a coiled member (130) over at least the distal portion of the treated elongate member (110); and
e. coupling ends of the coiled member (130) to at least the distal portion of the treated elongate member (110).
2. The method (200) as claimed in claim 1, wherein after passing the elongate member (110) between a plurality of rollers (201a), the method (200) includes grinding and deburring the distal portion of the elongate member (110) to provide a tapered profile to the distal portion of the elongate member (110).
3. The method (200) as claimed in claim 1, wherein after subjecting the distal portion of the elongate member (110) to the pre-defined temperature for the pre-defined time period, the method (200) includes quenching the elongate member (110) to the room temperature.
4. The method (200) as claimed in claim 1, wherein before subjecting the distal portion of the elongate member (110) to the pre-defined temperature for the pre-defined time period, the method (200) includes cutting the elongate member (110) to a pre-defined length ‘L’.
5. The method (200) as claimed in claim 1, wherein before subjecting the distal portion of the elongate member (110) to the pre-defined temperature for the pre-defined period, the method (200) includes shaping the distal portion of the elongate member (110) to a pre-defined shape by inserting the distal portion of the elongate member (110) into one or more tubular structures (207b) arranged in a pre-defined pattern of a mold (207a).
6. The method (200) as claimed in claim 1, wherein before subjecting the distal portion of the elongate member (110) to the pre-defined temperature for the pre-defined period, the method (200) includes shaping the distal portion of the elongate member (110) to a pre-defined shape by inserting the distal portion of the elongate member (110) into one or more a cavity of a mold to attain a predefined shape.
7. The method (200) as claimed in claim 1, wherein before sliding the coiled member (130) over at least the distal portion of the elongate member (110), the method (200) includes preparing the coiled member (130) by winding a cable having a diameter equal to the pitch of the of the coiled member (130).
8. The method (200) as claimed in claim 7, wherein preparing the coiled member (130) includes winding the cable around a mandrel (211a) having a shape corresponding to the elongate member (110).
9. The method (200) as claimed in claim 1, wherein sliding the coiled member (130) includes sliding the coiled member (130) over an entire length ‘L’ of the elongate member (110).
10. The method (200) as claimed in claim 1, wherein coupling the ends of the coiled member (130) to at least the distal portion of the treated elongate member (110) includes coupling the ends of the coiled member (130) to the elongate member (110) via dome shape welds (130a).
11. The method (200) as claimed in claim 1, wherein after coupling the ends of the coiled member (130) to the elongate member (110), the method (200) includes coupling a tubular member (150) to a proximal portion of the elongate member (110) wrapped with the coiled member (130).