A method of maintaining a long tubular implantable medical device straight

Abstract

This invention belongs to the field of medical device technology, specifically relating to a method for keeping a long, tubular implantable medical device straight. The method involves fixing one end of the long, tubular implantable medical device while applying external force to the other end to ensure the device remains straight. The method provided by this invention is simple and convenient, and simultaneously ensures the angle formed between the most inclined position of the long, tubular implantable medical device and the centerline of the fixing device. i ≤5°, thereby improving the uniformity of processed workpieces, the pass rate of processed products, and the accuracy of inspection.

Description

Technical Field

[0001] This invention belongs to the field of medical device technology, specifically relating to a method for keeping a long tubular implantable medical device straight. Background Technology

[0002] With the development of medical technology, implantable medical devices have gradually come into focus. They primarily function to provide support in the affected area, such as stent placement, a common procedure for vascular diseases. This involves placing a stent into the diseased area of ​​a blood vessel, causing the narrowed vessel to widen and restore normal blood supply, thus achieving revascularization. This is currently the most effective way to treat diseases caused by vascular stenosis and insufficient blood supply (such as coronary heart disease and lower extremity arteriosclerosis obliterans). However, because implantable medical devices are inserted into the human body, if factors in the manufacturing process lead to low pass rates or unstable quality, it can easily cause numerous safety issues and produce significant side effects in the patient, causing suffering. Therefore, countries around the world have set high standards and strengthened corresponding regulations for the quality and safety of implantable medical devices. Manufacturers must ensure that their products meet the relevant standards and minimize potential safety risks after implantation.

[0003] The production of medical devices often involves processes such as spraying, cutting, and testing. A common method in these processes is to hold one end of the medical device in a clamp while the other end is suspended in the air, allowing for the spraying, cutting, and testing to proceed. When the medical device is relatively short, the suspended end will not bend or sag due to gravity. Therefore, issues such as unstable manufacturing processes and low product qualification rates caused by gravity are generally avoided during processing. When the length of tubular medical devices increases to a certain value, especially for long tubular medical devices with hollow designs, the low surface material coverage and the overall lightness and thinness of the device make the suspended stent section prone to downward bending under gravity. This is particularly problematic during processes such as spraying, cutting, and testing, where the device needs to rotate within a certain speed and range. This can cause the front and rear central axes of the device to misalign, resulting in a noticeable "tail swing." This rapid swinging of the suspended section leads to a series of problems in the manufacturing process, such as uneven coating during spraying, uneven energy during laser cutting causing incomplete cuts or inconsistent rod thickness, or deviations in cutting position leading to uneven dimensions and low processing accuracy. Consequently, the final stent may cause problems such as thrombosis when used in the body. Therefore, it is necessary to provide a method to ensure that the stent remains straight throughout the manufacturing process, ensuring uniform coating on the stent surface, symmetrical cutting patterns, and high accuracy in testing results. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention provides a method for maintaining the straightness of long tubular implantable medical devices. This method ensures that long tubular implantable medical devices, especially hollowed-out long tubular implantable medical devices, remain in a relatively straight state throughout the processing or testing process. The angle formed by the line connecting the highest or lowest point the device passes through during the swinging process and the fixing point of the device's fixed end with the straight line containing the center line of the fixing device is... ≤5° or even ≤3°, which allows the pass rate of workpiece appearance and size in the processing process and the accuracy of inspection in the inspection process to reach 90% or even 95% or more.

[0005] The present invention provides a method for keeping a long tubular implantable medical device straight. The long tubular implantable medical device includes a fixed end and a suspended end, wherein an external force is applied to the suspended end to ensure that the device remains straight.

[0006] The long, tubular implantable medical device in this invention is relatively small. The longer the tubular device, the longer the suspended portion, and the more severe the tail-wagging phenomenon. In certain processing steps, because the device needs to be rotated continuously, it will experience significant tail-wagging due to gravity and its own inertia. The tail-wagging angle can reach 120°, that is, the angle formed by the lines connecting the highest and lowest points of the device during the swing to the fixed point of the device's fixed end is 2θ. During the swing, the value of 2θ can reach the range of 10°-120°. Especially when the long, tubular implantable medical device has a hollow structure, the tail-wagging is even more severe, and the swing angle 2θ can even reach 180°. Therefore, sufficient force needs to be applied to the surface of the device to achieve the effect of "straightening" the tail of the device.

[0007] It should be noted that the "highest point" and "lowest point" mentioned above refer to the center point of the device's end section when the device reaches its highest or lowest position during the swinging process.

[0008] In the above-mentioned technical solution provided by this invention, the external force provided is a magnetic field traction force; the magnitude of the magnetic field traction force acting on the implantable medical device is... Formula I

[0009] in, Let μ0 be the permeability of the magnetic medium in vacuum (i.e., vacuum permeability, where μ0 = 4π × 102). -7 N / A 2 ), x is the distance from the magnetic source to the outermost surface of the magnetically conductive material in the suspended end of the instrument, dχ is the integral of the distance from the magnetic source to the surface of the magnetically conductive material, h is the length of the magnetically conductive material on the instrument in the direction perpendicular to the surface, F 牵Let B be the total traction force exerted on the instrument by the magnetic field, B be the magnetic induction intensity of the magnetic field at the surface of the magnetically conductive material, and S be the area of ​​the surface of the magnetic field interacting with the magnetically conductive material.

[0010] The elongated tubular implantable medical device described in this invention can be induced by a magnetic field to generate a corresponding force, but the specific method by which the device surface is subjected to the magnetic field's traction force is not limited. In some cases, the elongated tubular implantable medical device itself is magnetically conductive; for example, in some embodiments, the entire suspended portion or even the entire device is magnetically conductive and can be subjected to the force of a magnetic field. In other embodiments, a portion of the device is magnetically conductive, such as the coating or main material of the device, or a material with magnetic properties (such as a radiolucent structure) exists on a certain cross-section of the device, causing the device to be subjected to the force of a magnetic field, thereby ensuring that the device can maintain a straight state. In other cases, the device itself is not magnetically conductive, but external magnetically conductive materials are used to enable the device to be subjected to the force of a magnetic field and thus maintain its straightness, such as attaching magnetically conductive patches to the outer surface of the device.

[0011] When the instrument itself is magnetically conductive, and its suspended portion or the entire instrument is magnetically conductive, such as when the instrument is made of pure iron or an iron alloy, the force exerted by the magnetic field on the instrument in this invention is: ,in Let μ0 be the permeability of the magnetic medium in vacuum, i.e., the vacuum permeability, μ0 = 4π × 10⁻⁶. -7 N / A 2 x is the distance from the magnetic source to the outermost working surface of the suspended end of the instrument, dχ is the integral of the distance from the magnetic source to the working surface of the instrument, h is the length of the suspended part of the instrument, and F 牵 Let B be the total traction force exerted on the instrument by the magnetic field, B be the magnetic field strength at the surface of the instrument, and S be the area of ​​the surface of the instrument.

[0012] In this invention, "the area S of the surface where the magnetic field interacts with the instrument" refers to the area of ​​the covering material of any circumferential cross-section of the instrument under magnetic force. When the instrument in this invention is a hollow tubular structure, "the area S of the surface where the magnetic field interacts with the instrument" refers to the area of ​​the instrument support rod on the cross-section, that is, S 支撑杆截面 The calculation formula is the circumferential cross-sectional area S of the instrument's outer diameter. 周向 Multiply by the coverage area S of the material covered by the instrument cross section 截面覆盖率 ,Right now:

[0013] S 器械杆截面 =S 周向 * S 截面覆盖率 Formula II

[0014] The coverage rate S of the material covered by the instrument on the cross section 截面覆盖率It refers to the area S occupied by the support rod across the entire circumferential cross-section. 支撑杆截面 Circumferential cross-sectional area S of the outer diameter of the support 周向 The ratio, that is:

[0015] S 截面覆盖率 = *100% Formula III

[0016] It should be noted that the S mentioned above... 截面覆盖率 S 周向 S 支撑杆截面 All figures are averages, and all areas are under the condition of instrument processing / during processing, not the area of ​​the instrument when it is implanted in the body and in use.

[0017] When the device in this invention is only partially magnetic (internal magnetic) or has magnetically conductive material attached to its outer surface (external magnetic), especially when the length of the magnetically conductive material at the internal or external magnetic location is very short or even negligible in the length direction of the device, the formula for the above-mentioned traction force can be:

[0018] Formula IV,

[0019] That is, the magnitude of the magnetic field pulling force on the instrument is only related to the area of ​​the magnetic material in the circumferential cross-section direction.

[0020] Because magnetic fields gradually weaken with increasing distance, in a constant magnetic field emitted by a magnetic source, the magnetic induction intensity decreases with distance from the source. Therefore, when the distance between the magnetic field and the outermost surface of the implantable medical device is greater, the magnetic induction intensity emitted by the magnetic source needs to be increased accordingly to ensure that the force acting on the device surface remains constant. When the distance between the magnetic source and the outermost surface of the implantable medical device is large, the required magnetic induction intensity can reach 1000 mT. When the distance between the magnetic source and the outermost surface of the implantable medical device is small, a magnetic induction intensity of 100 mT is sufficient. In the above-mentioned technical solution provided by the present invention, the magnetic induction intensity B of the magnetic field generated by the magnetic source is ≤1000 mT, including but not limited to any value below 1000 such as 200 mT, 300 mT, 400 mT, 500 mT, 600 mT, 700 mT, 800 mT, 900 mT, etc. Further, the magnetic induction intensity B of the magnetic field generated by the magnetic source is ≤750 mT or B≤600 mT, etc.

[0021] In the above-mentioned technical solution provided by this invention, the magnetic source that generates the magnetic field traction force can be any device and / or equipment capable of generating a magnetic field. It can be naturally magnetic, such as a commonly used permanent magnet, or a device or equipment that can generate a magnetic field under external force, such as generating a magnetic field when energized. Furthermore, the magnetic source described in this invention includes, but is not limited to, permanent magnets and electromagnets, and can be... magnet , Magnets, coils that generate magnetic fields, etc. It can be any one or more of the following: constant magnetic field, alternating magnetic field, pulsating magnetic field, and pulsed magnetic field. Furthermore, the number of magnetic field sources is not limited to one; it can be one or a combination of multiple sources.

[0022] In the above-mentioned technical solution provided by the present invention, the distance between the magnetic source and the outermost extended working surface of the suspended end of the implantable medical device is... The value range is 0.1 mm - 100 mm (including but not limited to 0.5 mm, 1 mm, 3 mm, 5 mm, 7 mm, 9 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm, 95 mm, 98 mm, etc.); further, the distance between the magnetic source and the outermost active surface of the suspended end of the implanted medical device. The value can be any two values ​​between 0.1 and 100 mm, such as 0.1 mm - 10 mm, 0.1 mm - 15 mm, 0.1 mm - 25 mm, 0.1 mm - 50 mm, 0.1 mm - 60 mm, 0.1 mm - 70 mm, 0.1 mm - 80 mm, 0.15 mm - 80 mm, 0.15 mm - 90 mm, etc.

[0023] In this invention, the outermost working surface of the suspended end of the implantable medical device is the circumferential cross section of the magnetic material at the point closest to the magnetic source along the radial surface of the device. When the entire device or the suspended part of the device in this invention is made of magnetic material, the outermost working surface of the suspended end of the implantable medical device refers to a circumferential cross section of the suspended end of the device that is in contact with the air and is perpendicular to the radial surface.

[0024] This invention provides a technical solution specifically for the processing of long, tubular implantable medical devices. The longer the implantable medical device, the lower its surface coverage. Due to gravity, the implantable medical device is more prone to bending and tailing during rotation or vibration. However, since the length of medical devices required / suitable for use in the human body is limited, this invention is applicable to long tubular devices with a suspended portion length of 5mm-200mm (including but not limited to suspended portion lengths of 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 110mm, 120mm, 130mm, 140mm, 150mm, 160mm, 170mm, 180mm, 190mm, 200mm, etc.). (mm, etc.) Keep straight, and further applicable to long tubular instruments within a new range of any two values ​​in the range of 5mm-200mm, where the length of the suspended part is 38mm-150mm, 38mm-140mm, 15mm-150mm, 15mm-140mm, 20mm-150mm, 20mm-140mm, etc.

[0025] In the above-mentioned technical solution provided by the present invention, in order to ensure that the instruments remain basically straight, that is, to ensure as much as possible the angle formed between the most inclined position of the instrument and the center line of the fixing device. The value is very small, which can control the included angle. The value is 5° or below, and can even reach 3° or below, thus ensuring that the pass rate of the workpiece's appearance and dimensions in the processing process and the inspection accuracy in the testing process can reach over 90%. Therefore, sufficient external force or magnetic traction force must be applied to the suspended end of the device. However, the magnetic traction force applied to the implantable medical device cannot be too large. If it is too large, the device may easily detach from the fixed end and lose stability. That is, the magnitude of the magnetic traction force acting on the implantable medical device needs to be less than the pulling force of the fixed end on the device to ensure that the fixed end of the device does not move left or right or up and down. In addition, when the long tubular implantable medical device in this invention has a hollow structure, if the applied external force is too large, it is easy to deform the device. Therefore, the magnitude of the magnetic traction force applied to the implantable medical device needs to be limited in the invention to ensure that the magnitude of the magnetic traction force acting on the device is moderate. In the technical solution provided by this invention, the magnitude of the magnetic field traction force acting on the device is 1-40 times the weight of the implanted medical device, including but not limited to 2, 3, 5, 7, 10, 12, 15, 18, 20, 23, 25, 28, 30, 35, 38, and 40 times. Furthermore, the magnitude of the magnetic field traction force acting on the implanted medical device is 1-28 times, 1-20 times, 5-35 times, 3-35 times, and 3-40 times the weight of the implanted medical device.

[0026] In the spraying process of long tubular implantable medical devices, the spraying liquid is very viscous. If the spraying liquid is sprayed onto the device end with the clamp during spraying, it can easily cause the device to stick to the clamp, resulting in the coating on the device surface being torn during separation from the clamp. Therefore, it is currently common practice to spray the device in two or more stages. This also requires that the length of the clamp at the holding end of the implantable medical device cannot exceed the length of the device; that is, the length of the device must be longer than the length of the clamp. In the above-mentioned technical solution provided by this invention, the length of the clamp is the length of the implantable medical device. The following can also be the following, the following, the following, The length of the clamps, even those located inside the instrument, can be 0 mm.

[0027] In the above-mentioned technical solutions provided by the present invention, the fixation method of the implantable medical device fixation end is diverse. It can be fixed by clamping, by physical interference fit, or by magnetic or chemical means. That is, the fixation methods of the device fixation end in the technical solutions provided by the present invention include, but are not limited to, clamping, physical interference fit, magnetic fixation, and chemical fixation.

[0028] The preparation method provided by the present invention is applicable to the processing of long tubular implantable medical devices with all outer diameters, wall thicknesses and coverage, and is especially suitable for the processing of hollow long tubular implantable medical devices, ensuring that the long tubular implantable medical devices remain straight during the processing.

[0029] In the above-mentioned technical solution provided by the present invention, the outer diameter of the long tubular implantable medical device is 1.0mm-20.0mm; further, the outer diameter of the long tubular implantable medical device is 1.0mm-15.0mm; even further, the outer diameter of the long tubular implantable medical device is 1.0mm-10.0mm.

[0030] In the above-mentioned technical solution provided by the present invention, the wall thickness of the long tubular implantable medical device is 10μm-600μm (including but not limited to 20μm, 30μm, 40μm, 50μm, 80μm, 100μm, 120μm, 150μm, 175μm, 200μm, 225μm, 250μm, 280μm, 300μm, 320μm, 350μm, 380μm, 400μm, 425μm, 450μm, 475μm, 500μm, 520μm, 550μm, 560μm, 580μm, 600μm, etc.); further, the wall thickness of the long tubular implantable medical device is 10μm-500μm; even further, the wall thickness of the long tubular implantable medical device is 15μm-450μm.

[0031] In the above-mentioned technical solutions provided by the present invention, the coverage rate of the cross-section of the long tubular implantable medical device is 0.1%-35% (including but not limited to 1%, 5%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22.5%, 25%, 28%, 30%, 33%, 34.5%, etc.); further, the coverage rate of the cross-section of the long tubular implantable medical device is 0.1%-30%; even further, the coverage rate of the cross-section of the long tubular implantable medical device is 0.1%-25%.

[0032] In the above-mentioned technical solution provided by the present invention, the long tubular implantable medical device has a hollow design, and the surface coverage of the device is 5%-60% (including but not limited to 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22.5%, 25%, 28%, 30%, 33%, 36%, 40%, 45%, 50%, 55%, 58%, etc.). Further, the surface coverage of the long tubular implantable medical device is 5%-55%. Even further, the surface coverage of the long tubular implantable medical device is a value within any two values ​​within the range of 5%-60%, such as 5%-50%, 8%-55%, 8%-50%, 10%-55%, 10%-50%, 8%-45%, 8%-40%, 5%-45%, 5%-40%, 10%-45%, 10%-40%, 8%-35%, or 10%-35%.

[0033] It should be noted that the "surface coverage of the instrument" in this invention refers to the surface coverage of the instrument material under the instrument diameter conditions during processing, that is, the ratio of the surface area covered by the instrument material to the total cylindrical side area of ​​the support coverage section, as shown in the following formula:

[0034] Surface coverage = A = Sr / Ss × 100% (1) Where:

[0035] Sr: The actual area filled / occupied on the outer surface of the instrument pattern during the processing. The outer surface area of ​​the bracket is measured by CAD software.

[0036] Ss: The total cylindrical lateral surface area of ​​the support covering section during processing, Ss=π×D1×L1(2)

[0037] D1: Diameter of the support during processing;

[0038] It should be noted that the "outer diameter," "wall thickness," "section coverage," and "surface coverage" of the long tubular implantable medical device in this invention refer to the corresponding values ​​of the long tubular implantable medical device in the processing state. That is, the values ​​of the "outer diameter," "wall thickness," "section coverage," and "surface coverage" of the tubular material to be processed or being processed into a long tubular implantable medical device.

[0039] In some embodiments of the technical solutions provided by this invention, the long tubular implantable medical device is a lumen prosthesis; further, it is a blood flow guiding device; and even further, it is a vascular support. In some embodiments of this invention, the long tubular implantable medical device is a stent; in other embodiments, it is a tube to be processed into a stent; in some embodiments, it is a semi-finished product to be processed into a final stent; in still other embodiments, it can be any long and lightweight implantable medical device for internal use; and in yet another embodiment, it is a raw material, semi-finished product, or finished stent to be processed into a stent.

[0040] In the above-mentioned technical solution provided by this invention, the implantable medical device itself is magnetically conductive; or a magnetic patch is added to the implantable medical device. The magnetic patch can be attached to any position on the device, but the effect is better when it is attached to the part without clamps and closer to the magnetic source. This includes, but is not limited to, adding magnetically conductive imaging points at both ends of the stent, or coating the surface of the stent with a magnetically conductive coating. Furthermore, the smaller the average distance between the magnetic patch and the magnetic source, the better. The number of magnetic patches attached in this invention can be one or more, and the shape of the magnetic patches is not limited, but they can cooperate with the magnetic field strength generated by the magnetic source and the distance between the device's working surface and the magnetic source to generate sufficient magnetic force to keep the stent in a straight state.

[0041] This method is applicable to multiple processes in the production of long tube instruments with hollowed-out designs, including but not limited to spraying, cutting, testing, and coating.

[0042] In some embodiments of the technical solutions provided by the present invention, the material of the device can be pure iron-based, iron-based alloy, or any other pure metal or alloy material with magnetic conductivity; in other embodiments, the material of the device can be polylactic acid or other substances that do not have magnetic conductivity.

[0043] The "fixing" described in this invention can be achieved by using the force generated by the interaction between the clamp and the instrument to fix the fixed end of the instrument in a specific position; it can also be achieved by using external force such as magnetic force to fix the fixed end of the instrument in a specific position; it can also be achieved by interference fit; or it can be achieved by the chemical action of a magnetic field, etc.

[0044] It should be noted that, for ease of description, the term "long tubular implantable medical device" has been simplified in this invention. That is, the terms "device," "medical device," and "implantable medical device" used in this invention all refer to "long tubular implantable medical device."

[0045] The “long tubular” implantable medical device described in this invention refers to a device whose length is greater than its outer diameter, especially a device whose suspended portion has a length greater than or equal to 5 mm, and more specifically a device whose suspended portion has a length greater than 10 mm.

[0046] In this invention, "tail-flicking" refers to the fact that the central axes of the front and rear ends of the instrument do not overlap during the processing.

[0047] In this invention, "straight" refers to the angle formed by the most inclined position of the implantable medical device and the center line of the fixation device. ≤5°.

[0048] It should be noted that the symbol " / " in this invention represents "or", such as "required / applicable in vivo" means required or applicable in vivo.

[0049] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used. Attached Figure Description

[0050] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. Wherein:

[0051] Figure 1 This is a schematic diagram of the bracket spraying state in Example 1;

[0052] Figure 2 This is a schematic diagram of the connection between the developing hole and the support in Example 5;

[0053] Figure 3 This is a schematic diagram of the state of the bracket cutting process in Example 6. Detailed Implementation

[0054] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0055] Test method:

[0056] For coating thickness testing, the stent is placed under an ultrasonic atomizing nozzle for spraying, covering the stent surface with a coating. Then, a Sensofar non-contact 3D optical profilometer is used to measure the coating thickness using white light interferometry. The coating thickness is measured at multiple locations throughout the stent, and the maximum and minimum coating thicknesses are compared; the difference between the two should ideally not exceed 2 μm.

[0057] The strut width test involves placing the cut struts under a 3D microscope for observation. The eye scans all struts, identifying and measuring the struts with the largest and smallest widths. Stumps with a width difference exceeding 16 μm are defined as male and female struts. The number of struts cut using male and female struts is then counted. This yields the following results:

[0058] Cutting size qualification rate = 1 - 100% × (number of male and female rod supports / number of cutting supports).

[0059] The length h of the suspended section of the support is determined by measuring the tilt angle. The height b between the center point of the farthest section of the support and the horizontal center line of the clamping section is measured. This height can be obtained using trigonometric functions. From this, we can obtain the magnitude of the tilt angle θ.

[0060] The cut appearance inspection involves placing the cut bracket under a three-dimensional microscope to observe whether there are any incomplete cuts on the bracket surface, and counting the number of brackets with incomplete cuts.

[0061] Therefore, the cut appearance qualification rate = number of incomplete blanking brackets / number of cutting brackets.

[0062] Example 1

[0063] A 118mm long iron-based absorbable drug-eluting peripheral stent (stent outer diameter 1.58mm, stent surface coverage 30%, stent wall thickness 70μm, stent circumferential cross-sectional support rod coverage 5%, stent mass m 112.53mg) was fixed at one end with a 59mm long clamp via physical interference fit. The length h of the unclamped section was 59mm, in order to emit the maximum magnetic induction intensity B. maxA 400mT magnet is used as the magnetic source to apply magnetic traction force to the support. When the magnet is positioned 1mm from the outermost surface of the suspended end of the support, the support remains relatively straight. The magnetic induction intensity B of the magnet at different positions is measured using a gaussmeter, and an exponential function curve of magnetic induction intensity versus distance x is fitted. Substituting this curve into the force F... 牵 The formula can be used to calculate F. 牵 =0.00844N, while the gravity F acting on the suspended part of this support is... 重 =0.00056N, therefore F 牵 ≈15F 重 At this point, the height b between the center point of the farthest section of the support and the horizontal center line of the clamping section is 3.09 mm. This can be calculated using trigonometric functions. =3° < 5°. The support structure in the above condition was placed under an ultrasonic atomizing nozzle for spraying. The coating thickness of the support structure after spraying was measured using a sensofar non-contact 3D optical profilometer. The difference between the maximum and minimum coating thickness was 0.5 μm.

[0064] Example 2

[0065] A 200mm long iron-based absorbable drug-eluting peripheral stent (stent outer diameter 1.58mm, stent surface coverage 30%, stent wall thickness 60μm, stent circumferential cross-sectional support rod coverage 4%, stent mass m 152.16mg) was fixed at one end with a 100mm long clamp via physical interference fit. The length h of the unclamped section was 100mm, in order to emit the maximum magnetic induction intensity B. max A 600mT magnet is used as the magnetic source to apply magnetic traction force to the support. When the magnet is positioned 1mm from the outermost surface of the suspended end of the support, the support can be kept relatively straight. The magnetic induction intensity B of the magnet at different positions is measured using a gaussmeter, and an exponential function curve of magnetic induction intensity versus distance x is fitted. Substituting this curve into the force F... 牵 The formula can be used to calculate F. 牵 = 0.01902N, while the gravity F acting on the suspended part of this support is... 重 =0.00076N, therefore F 牵 ≈25F 重 At this point, the height b between the center point of the farthest section of the support and the horizontal center line of the clamping section is 6.98 mm. This can be calculated using trigonometric functions. =4°<5°. The support structure in the above state was placed under an ultrasonic atomizing nozzle for spraying. The coating thickness of the support structure after spraying was measured using a sensofar non-contact 3D optical profilometer. The difference between the maximum and minimum coating thickness was 1 μm.

[0066] Example 3

[0067] A 38mm long iron-based absorbable drug-eluting peripheral stent (stent outer diameter 1.2mm, stent surface coverage 40%, stent wall thickness 80μm, stent circumferential cross-sectional support rod coverage 10%, stent mass m 22.83mg) was fixed at one end with a 15mm long clamp via physical interference fit. The length h of the unclamped section was 23mm, in order to emit the maximum magnetic induction intensity B. max A 300mT magnet is used as the magnetic source to apply magnetic traction force to the support. When the magnet is positioned 3mm from the outermost surface of the suspended end of the support, the support remains relatively straight. The magnetic induction intensity B of the magnet at different positions is measured using a gaussmeter, and an exponential function curve of magnetic induction intensity versus distance x is fitted. Substituting this curve into the force F... 牵 The formula can be used to calculate F. 牵 = 0.00209N, while the gravity F acting on the suspended part of this support is... 重 =0.00026N, therefore F 牵 ≈8F 重 At this point, the height b between the center point of the farthest section of the support and the horizontal center line of the clamping section is 2.00 mm. This can be calculated using trigonometric functions. =5°. The support structure in the above state was placed under an ultrasonic atomizing nozzle for spraying. The coating thickness of the support structure after spraying was measured using a sensofar non-contact 3D optical profilometer. The difference between the maximum and minimum coating thickness was 1 μm.

[0068] Example 4

[0069] A cobalt alloy support with a length of 118 mm (outer diameter of 2.4 mm, surface coverage of 20%, wall thickness of 100 μm, support rod coverage of 4% in the circumferential section, and mass m of 98.8 mg) is fixed at one end with a 50 mm long clamp using a physical interference fit. The length h of the unclamped section is 68 mm, in order to emit the maximum magnetic induction intensity B. max A 300mT magnet is used as the magnetic source to apply magnetic traction force to the support. When the magnet is positioned 1mm from the outermost surface of the suspended end of the support, the support can be kept relatively straight. The magnetic induction intensity B of the magnet at different positions is measured using a gaussmeter, and an exponential function curve of magnetic induction intensity versus distance x is fitted. Substituting this curve into the force F... 牵 The formula can be used to calculate F. 牵 = 0.00878N, while the gravity F acting on the suspended part of this support is... 重 =0.00057N, therefore F 牵 ≈15F 重 At this point, the height b between the center point of the farthest section of the support and the horizontal center line of the clamping section is 4.74 mm. This can be calculated using trigonometric functions. =4°<5°. The support structure in the above condition was placed under an ultrasonic atomizing nozzle for spraying. The coating thickness of the support structure after spraying was measured using a sensofar non-contact 3D optical profilometer. The difference between the maximum and minimum coating thickness was 0.5 μm.

[0070] Example 5

[0071] A 58mm long iron-based absorbable drug-eluting stent (stent outer diameter 8.0mm, stent surface coverage 11%, stent wall thickness 150μm, stent circumferential cross-sectional support rod coverage 0.8%, stent mass m 215.98mg) was fixed at one end with a 15mm long clamp via physical interference fit. The length h of the unclamped section was 43mm, in order to emit the maximum magnetic induction intensity B. max A 600mT magnet is used as the magnetic source to apply magnetic traction force to the support. When the magnet is positioned 3mm from the outermost surface of the suspended end of the support, the support remains relatively straight. The magnetic induction intensity B of the magnet at different positions is measured using a gaussmeter, and an exponential function curve of magnetic induction intensity versus distance x is fitted. Substituting this curve into the force F... 牵 The formula can be used to calculate F. 牵 = 0.04937N, while the gravity F acting on the suspended part of this support is... 重 =0.00160N, therefore F 牵 ≈31F 重 At this point, the height b between the center point of the farthest section of the support and the horizontal center line of the clamping section is 3.75 mm. This can be calculated using trigonometric functions. =5°. The support structure in the above state was placed under an ultrasonic atomizing nozzle for spraying. The coating thickness of the support structure after spraying was measured using a sensofar non-contact 3D optical profilometer. The difference between the maximum and minimum coating thickness was 1 μm.

[0072] Example 6

[0073] A magnesium alloy stent with a length of 68 mm and a mass of 57.26 mg (m) was cut at each end, with a cross-sectional area of ​​0.5 mm². 2 The developing holes are filled with a nickel material with good magnetic permeability (such as...). Figure 2 As shown), the clamp length is 30mm, and the length h of the bracket without clamping section is 38mm, in order to emit the maximum magnetic induction intensity B. max A 300mT magnet is used as the magnetic source to apply magnetic traction force to the support. When the magnet is positioned 3mm away from the developing hole, the support can be in a relatively straight state. Since the support only receives traction force at the developing point, and because the radial length h of the developing point on the support is too small, the traction force on the support is calculated according to the formula... Calculate F based on the magnetic flux density of the magnet at x=3, which is B=150mT as measured by a gaussmeter. 牵 =0.00447N, while the gravity F acting on the suspended part of this support is 0.00447N. 重 =0.00032N. At this time, F 牵 =14F 重 At this point, the height b between the center point of the farthest section of the support and the horizontal center line of the clamping section is 2.65mm. This can be calculated using trigonometric functions. =4°<5°. The support structure in the above condition was placed under an ultrasonic atomizing nozzle for spraying. The coating thickness of the support structure after spraying was measured using a sensofar non-contact 3D optical profilometer. The difference between the maximum and minimum coating thickness was 0.5 μm.

[0074] Example 7

[0075] One end of a 38mm long iron-based absorbable drug-eluting peripheral stent (stent outer diameter 1.58mm, stent surface coverage 30%, stent wall thickness 70μm, stent circumferential cross-sectional support rod coverage 5%, stent mass m 36.24mg) was fixed with a magnet. The length h of the unclamped section was 38mm, so as to emit the maximum magnetic induction intensity B. max A 400mT magnet is used as the magnetic source to apply magnetic traction force to the support. When the magnet is positioned 1mm from the outermost surface of the suspended end of the support, the support remains relatively straight. The magnetic induction intensity B of the magnet at different positions is measured using a gaussmeter, and an exponential function curve of magnetic induction intensity versus distance x is fitted. Substituting this curve into the force F... 牵 The formula can be used to calculate F. 牵 = 0.00844N, while the gravity F acting on the suspended part of this support is... 重 =0.00036N, therefore F 牵 ≈23F 重 At this point, the height b between the center point of the farthest section of the support and the horizontal center line of the clamping section is 1.99 mm. This can be calculated using trigonometric functions. =3°. The support structure in the above state was placed under an ultrasonic atomizing nozzle for spraying. The coating thickness of the support structure after spraying was measured using a sensofar non-contact 3D optical profilometer. The difference between the maximum and minimum coating thickness was 0.5 μm.

[0076] Example 8

[0077] Please see the appendix Figure 3A metal pipe with an outer diameter of 1.6 mm and a length of 200 mm is clamped in a fixed device. The material is fed by a rotating mechanism on the left at a constant speed of 6 mm / s, while the right side laser-cuts the metal into a specific pattern. When cutting a long support, as in state one, when only a small section of the support has been cut, the support maintains a certain straightness due to the hardness of the metal material, without affecting the energy of the laser reaching the material surface. However, when the support is cut to state two, the cut length reaches a certain value. When the length of the suspended, hollowed-out support is relatively long, the suspended end of the support tilts due to gravity. The tilt angle θ increases with the length of the section of the support with the completed pattern, causing a shift in the distance between the part of the support to be cut and the laser source from the originally set laser cutting distance. The greater the shift, the weaker the laser energy reaching the material surface, resulting in incomplete cutting or significant deviations in the size of the pattern after cutting. At this point, a variable electromagnetic source capable of emitting a magnetic field with a maximum intensity of 1000 mT is added to the suspended end of the support. The intensity of the emitted magnetic field can be adjusted by the magnetic source, and / or the intensity of the magnetic field on the suspended end of the metal tube can be adjusted by adjusting the distance between the magnetic source and the metal tube. In this embodiment, the magnetic source is initially set 5 mm away from the end of the support. As the metal tube moves towards the magnetic source, the hollowed-out support gradually lengthens, and the distance between the support and the magnetic source shortens. At this stage, the magnetic source does not need to be adjusted. As more of the metal rod is cut, the length of the suspended end increases, and the magnetic field strength is adjusted according to the distance / angle of the support from its original center position, ensuring that the angle of the support from the central axis remains within 5°. After cutting, the height b of the center point of the farthest section of the support and the horizontal center line of the clamping section is 13.95 mm. =4°<5°, and the cut bracket was placed in a three-dimensional microscope for inspection. The cut appearance qualification rate was 97% and the cut size qualification rate was 95%.

[0078] Comparative Example 1

[0079] A 118mm long iron-based absorbable drug-eluting peripheral stent (stent outer diameter 1.58mm, stent surface coverage 30%, stent wall thickness 70μm, stent circumferential cross-sectional support rod coverage 5%, stent mass m 112.53mg) was fixed at one end with a 59mm long clamp. The length h of the unclamped section was 59mm. At this time, the height b between the center point of the stent's farthest cross-section and the horizontal center line of the clamped section was 37.92mm. Calculate using trigonometric functions... =40°. The support structure in the above state was placed under an ultrasonic atomizing nozzle for spraying. The coating thickness of the support structure after spraying was measured using a sensofar non-contact 3D optical profilometer. The difference between the maximum and minimum coating thickness was 7 μm.

[0080] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. For example, this application uses a stent as an example for illustration only, and does not mean that the method provided in the present invention is only applicable to the processing of stents. Any other method of using magnets to keep long tubular implantable devices straight is within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method of maintaining a long tubular implantable medical device straight, the long tubular implantable medical device having a fixed end and a free end, the method comprising: The long tubular implantable medical device is applied with external force to ensure that the device remains straight; The external force is a magnetic field traction force; the magnetic field traction force acts on the implantable medical device with a size of wherein: is the magnetic permeability of the magnetic medium in vacuum, is the distance from the outermost surface of the magnetic permeable material in the suspended end of the long tubular implantable medical device to the magnetic source, dχ is the integral of the distance from the magnetic source to the surface of the magnetic permeable material, h is the length of the magnetic permeable material on the device in the direction perpendicular to the surface, F 牵 is the total magnetic field-induced force on the device, B is the magnetic flux density of the magnetic field at the surface of the magnetic permeable material, and S is the area of the surface of the magnetic permeable material on which the magnetic field acts.

2. The method of claim 1, wherein, The magnetic source generating the magnetic field traction force is a permanent magnet or an electromagnet.

3. The method of claim 1, wherein the method further comprises: The distance from the magnetic source to the outermost action surface of the magnetic conductive material in the suspended end of the long tubular implantable medical device The value range of the distance is 0.1 mm-100 mm.

4. The method of claim 1, wherein, The magnetic induction intensity of the magnetic field generated by the magnetic source is less than or equal to 1000 mT.

5. The method of claim 1, wherein, The length of the suspended part of the implantable medical device is 5 mm-200 mm.

6. The method of claim 1, wherein, The magnetic field traction force acting on the implantable medical device is 1-40 times the gravity of the suspended part of the implantable medical device.

7. The method of claim 1, wherein, Length L of the instrument to which the fixed end of the implantable medical instrument is fixed 固定 ≤ 2 / 3 L 器械 .

8. The method of claim 1, wherein, The fixation mode of the fixed end of the implantable medical device includes clamping, physical interference fit, magnetic force linkage, and chemical fixation.

9. The method of claim 1, wherein, The outer diameter of the long tubular implantable medical device is 1.0 mm-20.0 mm; and the wall thickness of the long tubular implantable medical device is 10 μm-600 μm.

10. The method of claim 1, wherein, The wall thickness of the long tubular implantable medical device is 10 μm-500 μm; and the outer diameter of the long tubular implantable medical device is 1.0 mm-15.0 mm.

11. The method of maintaining a long tubular implantable medical device straight according to claim 1, wherein, The coverage rate of the cross section of the long tubular implantable medical device is 0.1%-35%; and the coverage rate of the surface of the long tubular implantable medical device is 5%-60%.

12. The method of maintaining a long tubular implantable medical device straight according to claim 1, wherein, The coverage rate of the surface of the long tubular implantable medical device is 5%-55%; and the coverage rate of the cross section of the long tubular implantable medical device is 1%-30%.

13. The method of claim 1, wherein: The implantable medical device itself has magnetic permeability; or a magnetic permeable patch is added to the implantable medical device.

14. The method of claim 1, wherein: The long tubular implantable medical device is a raw material, a semi-finished product to be processed into a stent, or a finished product of a stent.

15. The method of claim 1, wherein: The magnetic induction intensity of the magnetic field generated by the magnetic source is 100 mT≤B≤1000 mT; the distance from the magnetic source to the outermost acting surface of the magnetic conductive material in the overhanging end of the long tubular implantable medical device is in the range of 0.5 mm-100 mm.

16. The method of claim 1, wherein: The distance from the magnetic source to the outermost action surface of the magnetic conductive material in the suspended end of the long tubular implantable medical device The value range of B is 0.15 mm-98 mm; the magnetic induction intensity of the magnetic field generated by the magnetic source is 100 mT≤B≤750 mT.

17. The method of claim 1, wherein: The distance from the magnetic source to the outermost action surface of the magnetic conductive material in the suspended end of the long tubular implantable medical device The value range of the distance is 3 mm-100 mm; the length of the suspended part of the implantable medical device is 10 mm-200 mm; the magnetic induction intensity of the magnetic field generated by the magnetic source is 100 mT≤B≤600 mT.

18. The method of maintaining a long tubular implantable medical device straight according to claim 1, wherein, The magnetic field traction force acting on the implantable medical device is 2-40 times the gravity of the implantable medical device.

19. The method of claim 1, wherein, The magnetic field traction force acting on the implantable medical device is 2-35 times the gravity of the suspended part of the implantable medical device.

20. The method of maintaining a long tubular implantable medical device straight according to claim 1, wherein, The wall thickness of the long tubular implantable medical device is 15 μm-450 μm; and the magnetic field traction force acting on the implantable medical device is 3-35 times the gravity of the suspended part of the implantable medical device.

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