A gradual transition thickened guidewire and method of making the same

Abstract

This invention provides a guidewire with a smooth transition and thickening, and its preparation method, relating to the field of medical device technology. The method includes heat-shrinking a tubular non-radioactive polymer onto a core wire to form a non-radioactive region coating layer, with the tip of the core wire exposed outside the non-radioactive region coating layer; then, fitting a tubular transition polymer and a tubular tip polymer onto the tip of the core wire, followed by heat treatment, where the tubular transition polymer forms a transition coating layer, and the tubular tip polymer forms a tip coating layer; the outer diameter of the tip coating layer is larger than the outer diameter of the non-radioactive region coating layer; one end of the transition coating layer is abutted with the tip coating layer, and the other end is abutted with the non-radioactive region coating layer, with the outer surface of the transition coating layer inclined from the end abutting with the tip coating layer to the other end abutting with the non-radioactive region coating layer. This solves the technical problem in existing guidewire abutment technology where the formation of a stepped, steep slope structure at the joint of two polymers with different outer diameters causes the mating device to experience bumps when passing through the steep transition.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a guidewire with a smooth transition and a method for its preparation. Background Technology

[0002] With the continuous development of interventional medicine, guidewire products are widely used and have permeated interventional procedures in various departments. Guidewires have the design features of strong support, soft tip, and some need for tip imaging. To increase tip imaging, bare metal guidewires usually use a welded imaging spring to provide imaging support, while polymer guidewires use a welded spring with a polymer outer layer, or a polymer coating layer containing imaging material to provide imaging support.

[0003] The structure of a guidewire typically involves dividing the metal wire into a burred zone and a non-burred zone. The burred zone is usually designed from coarse to fine and from hard to soft, ensuring that the tip is the softest end. During clinical use, the softest end passes through the stenotic lesion without damage, while the non-burred zone supports the lesion and provides a treatment channel for subsequent instruments. Polymer or polymer-spring guidewires consist of a metal wire coated with polymer to meet specific clinical needs (insulation in certain areas, reduced friction such as hydrophilic or hydrophobic lubrication, coloring, or markings, etc.). Currently, the mainstream polymer guidewire manufacturing process is as follows: A first polymer material is coated onto the metal wire. A circular resection is performed at a specific location from the tip (depending on clinical needs, this location may be in the range of 3-25 cm). The first polymer material is removed and peeled off, exposing the metal wire. Then, a second polymer containing a radiopaque material is joined (or a radiopaque spring is welded and then coated with a second polymer without radiopaque material; in this case, the first and second polymers can be different materials or the same material), thus achieving tip radiopaqueness.

[0004] However, existing guidewire docking techniques have the following main drawbacks: The first polymer is typically required to have a thinner single-sided wall thickness after coating (i.e., a smaller outer diameter at the first polymer location), while the second polymer, due to imaging requirements, should be as thick as possible within clinically necessary limits without affecting tip flexibility (i.e., a larger outer diameter at the second polymer location within medically acceptable conditions). Higher material thickness and imaging material content result in better opacity under X-rays, making clinical observation more obvious and facilitating doctors' observation of the guidewire's specific location (in the case of an imaging spring, this also leads to an increase in the outer diameter of the second polymer location, making it larger than that of the first polymer location). In existing technologies, to address the discrepancy between the outer diameters of the first and second polymer locations, the common approach is to widen the first polymer at the docking point (e.g.,...). Figure 1As shown in the figure, after the flaring, the polymer forms a step at the joint. After the ring is cut and the cut surface is treated, the second polymer is then joined. However, this method will result in a step-like steep slope structure at the joint of the first and second polymers. In actual use, when the instrument passes through the steep transition of the step, it will cause "bumps" and may damage the contact surface of the instrument. Users will also face the dilemma of "going up steep slope" when operating the instrument.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] One of the objectives of this invention is to provide a method for preparing a guidewire with a smooth transition and thickening, in order to solve the technical problem in existing guidewire docking technology where the formation of a stepped steep slope structure at the docking point of two polymers with different outer diameters causes the mating device to bounce when passing through the steep transition of the step.

[0007] The second objective of this invention is to provide a guidewire with a smooth transition in thickness.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a method for preparing the above-mentioned guidewire, comprising the following steps: A. A tubular non-developable polymer is heat-shrinked onto a core filament to form a non-developable area coating layer, with the tip of the core filament exposed outside the non-developable area coating layer. B. The tubular transition polymer and the tubular tip polymer are fitted onto the tip of the core wire, and after heat treatment, the tubular transition polymer forms a transition coating layer, and the tubular tip polymer forms a tip coating layer; The outer diameter of the tip coating layer is larger than the outer diameter of the non-developable area coating; One end of the transition coating layer is connected to the tip coating layer, and the other end is connected to the non-developable area coating layer. The outer surface of the transition coating layer extends from the end connected to the tip coating layer to the other end connected to the non-developable area coating layer.

[0009] Furthermore, the absolute difference between the melting point of the tubular tip polymer and the melting point of the tubular transition polymer is 0~50°C, and the melting point of the tubular non-developable polymer is at least 100°C higher than the melting point of the tubular transition polymer, and the temperature of the heat treatment is ≥ the maximum value of the melting point of the tubular tip polymer and the melting point of the tubular transition polymer.

[0010] Furthermore, the absolute value of the difference between the melting point of the tubular tip polymer and the melting point of the tubular transition polymer is 0~50℃, and the absolute value of the difference between the melting point of the tubular non-developable polymer and the melting point of the tubular transition polymer is 0~50℃, and the temperature of the heat treatment is ≥ the maximum value among the melting points of the tubular tip polymer, the tubular transition polymer, and the tubular non-developable polymer.

[0011] Furthermore, the tubular transition polymer is composed of several tubular transition polymer segments, which are arranged sequentially from small to large outer diameter along the tubular non-radioactive polymer toward the tubular tip polymer.

[0012] Furthermore, the number of the tubular transition polymer segments is 1 to 10.

[0013] Furthermore, if the hardness of the tubular non-recognizable polymer is greater than the hardness of the tubular tip polymer, then a plurality of the tubular transition polymer segments are arranged in order of increasing outer diameter along the direction from the tubular non-recognizable polymer to the tubular tip polymer, and in order of decreasing hardness. If the hardness of the tubular non-recognizable polymer is less than the hardness of the tubular tip polymer, then a plurality of the tubular transition polymer segments are arranged in order of increasing outer diameter along the direction from the tubular non-recognizable polymer to the tubular tip polymer, and in order of increasing hardness.

[0014] Furthermore, the heat treatment includes at least one of hot air heat treatment, infrared spot heat treatment, laser welding heat treatment, or oven constant temperature heat treatment.

[0015] Secondly, the present invention provides a guidewire with a smooth transition thickening, which is prepared by the above-described preparation method.

[0016] Furthermore, the guidewire includes a core wire, and a non-radioactive zone coating layer, a transition coating layer, and a tip coating layer arranged sequentially along the axial direction of the core wire from the operating end to the tip. The transition coating layer and the tip coating layer are an integral structure.

[0017] Furthermore, taking the extension line of the outer side of the non-developable area coating layer as the baseline, the tilt angle of the outer side of the transition coating layer is 0.5°~40°.

[0018] This invention provides a method for preparing a guidewire with a smooth transition and thickening. It uses a tubular polymer for looping, eliminating the need for flaring the tubular non-radioactive polymer (requiring no additional flaring equipment). This avoids the process difficulties caused by flaring and the complexity of flaring equipment, simplifying the process steps. Only raw materials of suitable thickness and material need to be selected and cut to a fixed length, then assembled using a looping method. In terms of process, the tubular non-radioactive polymer, tubular transition polymer, and tubular tip polymer are selected with different outer diameters, increasing in size, making it easy to see and preventing assembly errors. After heating, the tubular transition polymer fuses with the tubular tip polymer, forming a smooth, thickened transition slope between the non-radioactive area coating layer and the tip coating layer. This allows for a smooth transition, creating a stepless, gentle slope for the guidewire and the accompanying instrument, avoiding "bumps" and eliminating the problems associated with "steep slopes." Figure 1 Compared to existing guidewires with stepped structures, the guidewire of this invention has a smaller diameter at the joint with the non-radioactive coating layer, resulting in a smaller gap at the joint for the same degree of bending. This solves the technical problem in existing guidewire jointing technologies where the joint of two polymers with different outer diameters forms a stepped, steep slope structure, causing the mating instrument to bounce when passing through the steep transition of the step. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the guidewire structure in the prior art; Figure 2 This is a schematic diagram of a guide wire with a smooth transition and thickening provided in Embodiment 1 of the present invention; Figure 3 for Figure 2 Enlarged schematic diagram of the structure at point A in the middle; Figure 4 This is a schematic diagram of the axial cross-sectional structure of each tubular transition polymer segment and the tubular tip polymer during the preparation of a guidewire with a smooth transition and thickening, as provided in Embodiment 2 of the present invention. Figure 5 This is a schematic diagram of the axial cross-sectional structure of each tubular transition polymer segment and the tubular tip polymer during the preparation of a guidewire with a smooth transition and thickening, as provided in Embodiment 3 of the present invention. Figure 6 This is a schematic diagram of the axial cross-sectional structure of each tubular transition polymer segment and the tubular tip polymer during the preparation of a guidewire with a smooth transition and thickening provided in Embodiment 4 of the present invention.

[0021] Icons: 1-Core wire; 11-Tip; 2-Undeveloped area coating; 3-Transition coating; 4-Tip coating. Detailed Implementation

[0022] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0023] Unless otherwise stated, the methods and techniques of the present invention are generally carried out according to conventional methods well known in the art and as described in various general and more specific references, which are cited and discussed throughout this specification.

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The present invention provides a method for preparing the above-mentioned guidewire, comprising the following steps: A. The tubular non-developable polymer is thermally shrunken onto the core filament 1 to form a non-developable area coating layer 2, with the tip 11 of the core filament 1 exposed outside the non-developable area coating layer 2. B. The tubular transition polymer and the tubular tip polymer are fitted onto the tip 11 of the core wire 1. After heat treatment, the tubular transition polymer forms the transition coating layer 3, and the tubular tip polymer forms the tip coating layer 4. The outer diameter of the tip coating layer 4 is larger than the outer diameter of the non-developable area coating layer 2; One end of the transition coating layer 3 is connected to the tip coating layer 4, and the other end is connected to the non-developable area coating layer 2. The outer surface of the transition coating layer 3 is inclined from the end connected to the tip coating layer 4 to the other end connected to the non-developable area coating layer 2.

[0026] Using tubular polymers for the looping operation eliminates the need for flaring the tubular non-radioactive polymer (requiring no additional flaring equipment), avoiding the process difficulties caused by flaring and the complexity of flaring equipment. This simplifies the process; only raw materials of suitable thickness and material need to be selected and cut to a fixed length for assembly via looping. The tubular non-radioactive polymer, tubular transition polymer, and tubular tip polymer are selected with different outer diameters, increasing in size, making it easy to identify and preventing assembly errors. After heating, the tubular transition polymer fuses with the tubular tip polymer, forming a thickened transition slope between the non-radioactive area coating layer 2 and the tip coating layer 4. This allows for a smooth and gradual transition, creating a stepless, gentle slope between the guidewire and the fitting instrument, avoiding "bumps" and eliminating the problems associated with "steep slopes." Figure 1 Compared to existing guidewires with stepped structures, the guidewire of this invention has a smaller diameter at the joint with the non-radioactive coating layer 2, resulting in a smaller gap at the joint for the same degree of bending. This solves the technical problem in existing guidewire jointing technologies where the joint of two polymers with different outer diameters forms a stepped, steep slope structure, causing the mating instrument to bounce when passing through the steep transition of the steps.

[0027] In some specific embodiments, before heat treatment, one end of the tubular transition polymer is preferably in contact with the tubular non-developable polymer, and the other end is in contact with the tubular tip polymer. This avoids the formation of cold spots at the gaps, which could lead to incomplete fusion. Contact connection specifically refers to a tight fit between the end faces.

[0028] The tubular transition polymer and the tubular tip polymer have the same or similar melting points, and they can only be fused together after heat treatment. In some specific embodiments, the absolute difference between the melting point of the tubular tip polymer and the melting point of the tubular transition polymer is 0°C to 50°C, and the melting point of the tubular non-developable polymer is at least 100°C higher than that of the tubular transition polymer. The heat treatment temperature is ≥ the maximum of the melting points of the tubular tip polymer and the tubular transition polymer.

[0029] The absolute value of the difference between the melting point of the tubular non-developable polymer and the tubular transition polymer can be 100℃, 200℃, or 300℃ or higher. Since the melting point of the tubular non-developable polymer differs significantly from that of the tubular transition polymer, the heat treatment temperature is set based on the maximum value between the melting points of the tubular tip polymer and the tubular transition polymer. Heating at a temperature higher than the polymer's melting point causes the tubular tip polymer and the tubular transition polymer to fuse under heat treatment, ensuring the thermal fusion of the tip coating layer 4 and the transition coating layer 3. This preserves the gradual transition of the transition coating layer 3, forming a gentle slope and preventing microphase separation at the thermal fusion cross-section. At this temperature, although the tubular transition polymer and the tubular non-developable polymer will not fuse, compared with the prior art which uses a stepped surface structure and has a large outer diameter, resulting in a large gap when bending, the tubular transition polymer and the tubular non-developable polymer in this invention are in close contact before heat treatment, and the difference in outer diameter at the joint is significantly reduced. Therefore, even when bending at this gap, the gap is much smaller than that of the prior art.

[0030] To prevent gaps, in some specific embodiments, the absolute difference between the melting point of the tubular tip polymer and the tubular transition polymer is 0~50°C, and the absolute difference between the melting point of the tubular non-developable polymer and the tubular transition polymer is also 0~50°C. The heat treatment temperature is greater than or equal to the maximum value among the melting points of the tubular tip polymer, the tubular transition polymer, and the tubular non-developable polymer. Since the melting points of the tubular tip polymer, the tubular transition polymer, and the tubular non-developable polymer are the same or similar, they meet the conditions for fusion. The heat treatment temperature is set based on the maximum melting point. During heat treatment, the section of the tubular non-developable polymer closest to the tubular transition polymer will also fuse with the tubular transition polymer, eliminating gaps between the tubular non-developable polymer and the tubular transition polymer.

[0031] In some specific embodiments, the tubular transition polymer is composed of several tubular transition polymer segments, which are arranged sequentially from small to large outer diameter along the direction from the tubular non-developable polymer to the tubular transition polymer. The tubular transition polymer is used in a segmented grouping ring operation to increase the polymer thickness and achieve thickening, which retains the development requirements while realizing the fusion of two polymers with different outer diameters and precisely controlling the slope formed.

[0032] The number of tubular transition polymer segments can be selected according to the specific application scenario of the guidewire. Specifically, the inner diameter of the tubular transition polymer segment can be determined based on the size of the core wire 1 at the docking point, the outer diameter of the tubular non-radioactive polymer determines the outer diameter of the first tubular transition polymer segment, and the outer diameter of the tubular tip polymer determines the outer diameter of the last tubular transition polymer segment. The number and width need to be matched and combined according to the size of the non-radioactive area coating layer 2 (tubular non-radioactive polymer) and the tip coating layer 4 (tubular tip polymer). In some specific embodiments, the outer diameter of the tubular transition polymer segment is 0.1mm~1.0mm; in some specific embodiments, the width of the tubular transition polymer segment is 0.4mm~10mm.

[0033] To better control the angle, in some specific implementations, the number of tubular transition polymer segments is 1 to 10. Specifically, the number of tubular transition polymer segments can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, depending on the actual transition effect.

[0034] To address the issues of stress concentration and slow hardness transition during guidewire bending, in some specific implementations, if the hardness of the tubular non-radioactive polymer is greater than that of the tubular transition polymer, then several tubular transition polymer segments are arranged sequentially from small to large outer diameter along the direction from the tubular non-radioactive polymer to the tubular transition polymer, and in descending order of hardness; if the hardness of the tubular non-radioactive polymer is less than that of the tubular transition polymer, then several tubular transition polymer segments are arranged sequentially from small to large outer diameter along the direction from the tubular non-radioactive polymer to the tubular transition polymer, and in ascending order of hardness.

[0035] The hardness of several tubular transition polymer segments can change slowly, transitioning from a hardness similar to that of the tubular non-developable polymer to a hardness similar to that of the tubular transition polymer.

[0036] In some specific embodiments, the outer diameter of the tubular non-reproducible polymer is 0.2~1.0 mm; in some specific embodiments, the material of the tubular non-reproducible polymer is selected from at least one of PTFE, thermoplastic PTFE mixtures, TPU-type thermoplastic polyurethane elastomers, TPU-type thermoplastic polyurethane elastomer mixtures, PEBAX-type polyether block amide polymers, or PEBAX-type polyether block amide mixtures. The material possesses elasticity and shrinkage properties.

[0037] In some specific embodiments, the outer diameter of the tubular tip polymer is 0.2~1.0 mm; in some specific embodiments, the material of the tubular tip polymer is selected from at least one of PTFE containing a developing material, thermoplastic PTFE mixtures, TPU-type thermoplastic polyurethane elastomers, TPU-type thermoplastic polyurethane elastomer mixtures, PEBAX-type polyether block amide polymers, or PEBAX-type polyether block amide mixtures, and the material has elasticity and shrinkage. The developing material is a precious metal material that is not transparent to X-rays, specifically selected from at least one of gold, silver, platinum alloys, or tungsten. Alternatively, a developing spring can be welded to the tip before covering the tubular tip polymer. In embodiments with a developing spring, the tubular tip polymer may not contain a developing material.

[0038] To ensure fusion between the tubular transition polymer and the tubular tip polymer, the material of the tubular transition polymer is similar to that of the tubular tip polymer, achieving mutual fusion. In some specific embodiments, the tubular transition polymer is selected from at least one of PTFE, thermoplastic PTFE blends, TPU-type thermoplastic polyurethane elastomers, TPU-type thermoplastic polyurethane elastomer blends, PEBAX-type polyether block amide polymers, or PEBAX-type polyether block amide blends, and the material possesses elasticity and shrinkage; it can also be at least one of the above-mentioned polymers containing a developing material. The developing material is a precious metal material that is not X-ray transparent, specifically selected from at least one of gold, silver, platinum alloys, or tungsten. Alternatively, a developing spring can be welded to the tip before covering the tubular tip polymer.

[0039] In some specific implementations, the heat treatment includes at least one of hot air heat treatment, infrared spot heat treatment, laser welding heat treatment, or oven constant temperature heat treatment.

[0040] According to another aspect of the present invention, a guidewire with a smooth transition thickening is also provided, which is prepared by the above-described preparation method.

[0041] In some specific embodiments, the guidewire includes a core wire 1, and a non-recognizable area covering layer 2, a transition covering layer 3, and a tip covering layer 4 arranged sequentially along the axial direction of the core wire 1 from the operating end to the tip 11; the outer diameter of the tip covering layer 4 is larger than the outer diameter of the non-recognizable area covering layer 2; one end of the transition covering layer 3 is connected to the tip covering layer 4, and the other end is connected to the non-recognizable area covering layer 2, and the outer surface of the transition covering layer 3 is inclined from the end connected to the tip covering layer 4 to the other end connected to the non-recognizable area covering layer 2.

[0042] The guidewire provided by this invention is provided with a transition coating layer 3. The outer surface of the transition coating layer 3 is inclined from one end that mates with the tip coating layer 4 to the other end that mates with the non-contrast coating layer 2. This forms a gradual, thickened slope, creating a stepless, gentle slope for the guidewire and the accompanying instruments, avoiding "bumps" and eliminating the problems associated with "steep slopes".

[0043] In some specific implementations, the extension line of the outer surface of the non-recognizable area coating layer 2 is used as the baseline, and the tilt angle α of the outer surface of the transition coating layer 3 is 0.5°~40°. This allows for better instrument passage.

[0044] In some specific embodiments, the transition coating layer 3 and the tip coating layer 4 are an integral structure. This eliminates mechanical joint gaps and ensures uniform distribution of bending stress.

[0045] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0046] Example 1 A 0.035-inch guidewire suitable for endoscopic diagnosis and intervention in the urinary and digestive tracts, its structure is as follows: Figure 2 As shown, a non-developable area coating layer 2, a transition coating layer 3, and a tip coating layer 4 are sequentially arranged along the axial direction of the core wire 1 from the operating end to the tip 11. The outer diameter of the tip coating layer 4 is larger than that of the non-developable area coating layer 2. One end of the transition coating layer 3 is connected to the tip coating layer 4, and the other end is connected to the non-developable area coating layer 2. The transition coating layer 3 and the tip coating layer 4 are an integral structure. The outer surface of the transition coating layer 3 is inclined from the end connected to the tip coating layer 4 to the end connected to the non-developable area coating layer 2. Using the extension line of the outer surface of the non-developable area coating layer 2 as a baseline, the inclination angle of the outer surface of the transition coating layer 3 is 0.5°≤α≤40°. Specifically, this inclination angle can be adjusted by adjusting the length of the transition coating layer 3 according to the difference between the outer diameter of the tip coating layer 4 and the outer diameter of the non-developable area coating layer 2.

[0047] Example 2 The 0.035-inch guide provided in Example 1 is suitable for endoscopic diagnosis and intervention in the urinary and digestive tracts.

[0048] 1. Materials Core wire 1 (NITI alloy wire): A super-elastic nickel-titanium alloy wire with a diameter of 0.58 mm and a length of 4500 mm is selected. The tip 11 of the nickel-titanium wire is a tapered section with an outer diameter of 0.24 mm, which makes the tapered section more flexible and the head end has good flexibility. The non-grinding section has good support.

[0049] Tubular non-developable polymer: A hollow polymer tube made of a PEBAX-type polyether block amide mixture with an outer diameter of 0.44 mm at the joint after coating treatment is selected. The inner diameter matches the core wire 1. The melting point is 190℃ and the hardness is 95A.

[0050] Tubular tip polymer: Specifically, a hollow polymer tube made of a PEBAX-type polyether block amide mixture (containing developing material) with an overall outer diameter of 0.60 mm is selected. The inner diameter matches the core wire 1. The melting point is 190℃ and the hardness is 60A.

[0051] Tubular transition polymer: The outer diameter of the non-radioactive area coating layer 2 (tubular non-radioactive polymer) of the guidewire is 0.44 mm, the outer diameter of the tip coating layer 4 (tubular tip polymer) of the guidewire is 0.60 mm, and the guidewire transition coating layer 3 (tubular transition polymer) is planned as follows: the inner diameter of each tubular transition polymer segment in the segmented group of tubular transition polymer is 0.24 mm, and the width is 1 mm. The outer diameter of the first segment of the group is 0.44 mm, which is connected to the non-radioactive area coating layer 2 (tubular non-radioactive polymer). The outer diameters of the second segment are 0.46 mm, the third segment is 0.48 mm, the fourth segment is 0.50 mm, the fifth segment is 0.52 mm, the sixth segment is 0.54 mm, the seventh segment is 0.56 mm, and the eighth segment is 0.58 mm. There are 8 groups in total, with a total interval of 8mm to achieve a slow transition. The material is a PEBAX-type polyether block amide mixture. The inner diameter matches the core wire 1. The melting point is 190℃. The hardness of the first to eighth segments is 95A, 90A, 85A, 80A, 75A, 70A, 65A, and 60A, respectively.

[0052] 2. Preparation of guidewire Combination Figures 3-4 The process involves first heat-shrinking a tubular non-radioactive polymer onto the core wire 1, then performing a circular excision to remove and peel off the first polymer material, exposing the metal wire. This exposed wire is positioned at a specific point relative to the tip (the distance from the tip may be 3-25 cm, depending on clinical needs), forming a non-radioactive area coating layer 2. Next, a tubular transition polymer and a tubular tip polymer are fitted onto the core wire 1, with one end of the transition polymer contacting the tubular non-radioactive polymer and the other end contacting the tubular tip polymer. Infrared spot heat treatment is then performed, resulting in the tubular non-radioactive polymer forming the non-radioactive area coating layer 2, the tubular transition polymer forming the transition coating layer 3, and the tubular tip polymer forming the tip coating layer 4. The heat treatment temperature is 200°C, and the tilt angle α of the outer surface of the transition coating layer 3 in the resulting guidewire is 0.57°.

[0053] Example 3 Combination Figure 5To illustrate, unlike Example 2, in this example, the core wire 1 at the docking location has a size of 0.24 mm, the outer diameter of the non-radioactive coating layer 2 (tubular non-radioactive polymer) is 0.44 mm, the outer diameter of the tip coating layer 4 (tubular tip polymer) is 0.60 mm, and the transition coating layer 3 (tubular transition polymer) is designed as follows: the inner diameter of each tubular transition polymer segment in the group is 0.24 mm, and the width is 2 mm. The outer diameter of the first segment in the group is 0.44 mm, the outer diameter of the second segment is 0.48 mm, the outer diameter of the third segment is 0.52 mm, and the outer diameter of the fourth segment is 0.56 mm. There are a total of 4 groups, with a total interval of 8 mm, to achieve a slow transition. The tilt angle α of the outer surface of the transition coating layer 3 in the fabricated guidewire is 0.57°.

[0054] Example 4 Combination Figure 6 To illustrate, unlike Example 2, in this example, the core wire 1 at the docking point has a size of 0.24 mm, the outer diameter of the non-radioactive area coating layer 2 (tubular non-radioactive polymer) is 0.44 mm, the outer diameter of the tip coating layer 4 (tubular tip polymer) is 0.60 mm, and the inner diameter of the transition coating layer 3 (tubular transition polymer) is 0.24 mm, the width is 2 mm, and the outer diameter is 0.50 mm. One end is docked with the non-radioactive area coating layer 2 (tubular non-radioactive polymer), and the other end is docked with the tip coating layer 4 (tubular tip polymer), achieving a slow transition. The tilt angle α of the outer surface of the transition coating layer 3 in the resulting guidewire is 2.29°.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a guidewire with a smooth transition and thickening, characterized in that, Includes the following steps: A. The tubular non-developable polymer is heat-shrinked onto the core wire (1) to form a non-developable area coating layer (2), and the tip (11) of the core wire (1) is exposed outside the non-developable area coating layer (2); B. The tubular transition polymer and the tubular tip polymer are fitted onto the tip (11) of the core wire (1) and heat-treated to form a transition coating layer (3) of the tubular transition polymer and a tip coating layer (4) of the tubular tip polymer. The outer diameter of the tip coating layer (4) is larger than the outer diameter of the non-developable area coating layer (2); One end of the transition coating layer (3) is connected to the tip coating layer (4), and the other end is connected to the non-developable area coating layer (2). The outer surface of the transition coating layer (3) is inclined from the end connected to the tip coating layer (4) to the other end connected to the non-developable area coating layer (2).

2. The preparation method according to claim 1, characterized in that, The absolute value of the difference between the melting point of the tubular tip polymer and the melting point of the tubular transition polymer is 0~50°C, and the melting point of the tubular non-developable polymer is at least 100°C higher than the melting point of the tubular transition polymer, and the temperature of the heat treatment is ≥ the maximum value of the melting point of the tubular tip polymer and the melting point of the tubular transition polymer.

3. The preparation method according to claim 1, characterized in that, The absolute value of the difference between the melting point of the tubular tip polymer and the melting point of the tubular transition polymer is 0~50℃, and the absolute value of the difference between the melting point of the tubular non-developable polymer and the melting point of the tubular transition polymer is 0~50℃, and the temperature of the heat treatment is ≥ the maximum value among the melting points of the tubular tip polymer, the tubular transition polymer, and the tubular non-developable polymer.

4. The preparation method according to claim 1, characterized in that, The tubular transition polymer is composed of several tubular transition polymer segments, which are arranged sequentially from small to large outer diameter along the tubular non-radioactive polymer toward the tubular tip polymer.

5. The preparation method according to claim 4, characterized in that, The number of tubular transition polymer segments is 1 to 10.

6. The preparation method according to claim 4, characterized in that, If the hardness of the tubular non-recognizable polymer is greater than the hardness of the tubular tip polymer, then a plurality of the tubular transition polymer segments are arranged in order of increasing outer diameter along the direction from the tubular non-recognizable polymer to the tubular tip polymer, and in order of decreasing hardness. If the hardness of the tubular non-recognizable polymer is less than the hardness of the tubular tip polymer, then a plurality of the tubular transition polymer segments are arranged in order of increasing outer diameter along the direction from the tubular non-recognizable polymer to the tubular tip polymer, and in order of increasing hardness.

7. The preparation method according to any one of claims 1 to 6, characterized in that, The heat treatment includes at least one of hot air heat treatment, infrared spot heat treatment, laser welding heat treatment, or oven constant temperature heat treatment.

8. A guidewire with a smooth, gradually thickened transition, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 7.

9. The guidewire according to claim 8, characterized in that, The guidewire includes a core wire (1), and a non-radioactive area covering layer (2), a transition covering layer (3) and a tip covering layer (4) arranged sequentially from the operating end to the tip (11) along the axial direction of the core wire (1). The transition coating layer (3) and the tip coating layer (4) are an integral structure.

10. The guidewire according to claim 9, characterized in that, With the extension line of the outer side of the non-developable area coating layer (2) as the baseline, the tilt angle of the outer side of the transition coating layer (3) is 0.5°~40°.

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