Micro-catheter based on laser etching hollow structure and preparation method of micro-catheter

Abstract

The invention relates to the technical field of medical instruments, and discloses a micro catheter based on a laser etching hollow structure and a preparation method of the micro catheter. A plurality of laser etching notches are formed in the outer surface of the outer pipe component, each laser etching notch comprises a near-end non-through area and a far-end through area in the axial direction, and the cross section of each far-end through area is of a symmetrical structure with the middle narrowed and the two ends expanded. A laser etching notch with a near-end non-through area and a far-end through area is formed in the surface of an outer pipe component, part of wall thickness is reserved in the near-end area to maintain the axial rigidity, the far-end area is completely through and is of a symmetrical structure with the middle narrowed and the two ends expanded, and the local flexibility is remarkably improved; through the synergistic effect of the structural design and the lining layer, stress distribution is more uniform when the microcatheter is bent, and stress concentration is avoided, so that the anti-fatigue life of the catheter is greatly prolonged, and the structural reliability of the catheter is greatly improved while the excellent bending performance is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, and in particular to a microcatheter based on a laser-etched hollow structure and a preparation method thereof. BACKGROUND

[0002] In the medical field, guide wires and catheters are important tools for performing precise surgeries. They can penetrate the human vasculature and complete high-difficulty medical operations. During surgery, doctors usually insert catheters through the femoral artery, radial artery, carotid artery, or jugular vein of patients, and guide them to pass through the complex vasculature, and finally reach the key target anatomical structures such as the heart and brain. In actual operation, doctors will first accurately route the guide wire to the target area, and then guide one or more catheters along the guide wire to the designated position. Once the catheter is in place, it can perform tasks such as sucking clots, removing other occlusions, or delivering therapeutic substances or devices such as drugs, stents, embolic devices, and radiopaque dyes.

[0003] In the field of microcatheters, to improve their ability to pass through curved parts of the vasculature, notches are usually etched on the catheter wall to enhance its bending flexibility. However, this design also brings new problems: when the microcatheter is too flexible, if an axial force is applied from the proximal end, the catheter may be compressed axially, showing a shape similar to an accordion, rather than effectively transmitting the force to the distal end. This can seriously affect the accuracy of surgical operations, making it difficult for doctors to accurately control the distal end of the microcatheter to reach the target anatomical structure.

[0004] Therefore, it is necessary to provide a microcatheter based on a laser-etched hollow structure and a preparation method thereof to solve the above technical problems. SUMMARY

[0005] The present application overcomes the shortcomings of the prior art and provides a microcatheter based on a laser-etched hollow structure and a preparation method thereof, which allows effective axial stiffness without excessively compromising its bending flexibility.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows: a microcatheter based on a laser-etched hollow structure, comprising:

[0007] an outer tube member;

[0008] an inner lining layer arranged on the inner wall of the outer tube member; and

[0009] a plurality of laser-etched notches opened on the outer surface of the outer tube member, each of the laser-etched notches comprising in the axial direction:

[0010] a proximal non-penetrating region in the shape of a rectangle, with an etching depth less than the wall thickness of the outer tube member;

[0011] a distal through region with an etching depth equal to the wall thickness of the outer tube member;

[0012] wherein the cross-sectional shape of the distal through region is a symmetrical structure with a narrowed middle and expanded two ends, and the side close to the proximal non-through region is conformally connected with the proximal non-through region;

[0013] The inner lining layer completely covers all the distal through regions on the outer tube member.

[0014] In a preferred embodiment of the present application, the circumferential angular interval between the center lines of adjacent laser etched notches on a single circumferential layer with N laser etched notches is not equal.

[0015] In a preferred embodiment of the present application, in the next 4-6 continuous axial layers, the center lines of the laser etched notches between adjacent axial layers have a circumferential angular offset of 5-15°, and the offset direction is opposite to that of the previous continuous axial layer. Through the arrangement of the laser etched notches, a continuous and uninterrupted solid axial beam is constructed between the laser etched notches, forming a physical connection path from the proximal end to the distal end of the microcatheter, thereby ensuring that the axial thrust can be efficiently and low-loss transmitted through the solid axial beam.

[0016] In a preferred embodiment of the present application, the etching depth of the proximal non-through region is 30-60% of the wall thickness of the outer tube member.

[0017] In a preferred embodiment of the present application, the cross-sectional shape of the distal through region is composed of two mirror-image right trapezoids; wherein the right-angle waists of the two right trapezoids are collinear and jointly form a connecting side shared with the long side of the rectangle of the proximal non-through region; the lower bases of the two right trapezoids are located at the two ends in the notch width direction, and their lengths are greater than the length of the middle narrow notch formed by the upper bases of the two trapezoids.

[0018] In a preferred embodiment of the present application, the axial length of the proximal non-through region is consistent with that of the distal through region.

[0019] In a preferred embodiment of the present application, the outer tube member and the inner lining layer are both made of high molecular materials, and the modulus of the high molecular material of the inner lining layer is much lower than that of the outer tube member.

[0020] A preparation method of a microcatheter, comprising the following steps:

[0021] S1, preparing an outer tube member;

[0022] S2, etching a plurality of the laser-etched notches on the outer surface of the outer tube member using a laser, the etching depth being controlled to be a preset depth of the proximal non-through region, to form an initial notch;

[0023] S3, performing secondary laser etching on the distal end portion of the initial notch formed in step S2, the etching depth being equal to the remaining wall thickness at the position, to form the distal through region and make the region completely through;

[0024] S4, integrating an inner lining layer on the inner wall of the outer tube member, so that the inner lining layer completely covers and seals all the distal through regions.

[0025] In a preferred embodiment of the present application, in the S4, a flexible high polymer thin-walled tube prepared in advance is inserted into the inner cavity of the outer tube member, and the thin-walled tube is expanded and attached to the inner wall of the outer tube member by applying gas pressure and heat treatment, to form the inner lining layer.

[0026] In a preferred embodiment of the present application, the outer tube member and the inner lining layer are both made of polymer materials, and the melting point of the polymer material of the inner lining layer is lower than that of the polymer material of the outer tube member.

[0027] The present application solves the defects in the background art and has the following beneficial effects:

[0028] (1) The present application provides a microcatheter based on a laser-etched hollow structure, which has laser-etched notches with a proximal non-through region and a distal through region on the surface of the outer tube member. The proximal region retains part of the wall thickness to maintain axial stiffness, and the distal region is completely through and has a symmetrical structure with a narrowed middle part and expanded two ends, which significantly improves the local flexibility. The synergistic effect of this structure design and the inner lining layer makes the stress distribution more uniform when the microcatheter is bent, avoiding stress concentration, thereby greatly improving the fatigue life and structural reliability of the catheter while ensuring excellent bending performance. Compared with the existing conventional rectangular or spiral groove structure, it is more suitable for long-term use in complex blood vessel environments.

[0029] (2) The present application adopts a notch arrangement strategy of circumferential asymmetric arrangement and axial staggered alignment, the circumferential angle interval between adjacent notches is not equal, and there is periodic reverse offset every 4-6 layers in the axial direction, forming a continuous and uninterrupted solid axial beam network, which ensures that the axial thrust can be efficiently and lowly transmitted from the proximal end to the distal end, effectively inhibiting the "accordion effect" in the pushing process. Compared with the existing symmetrical or spiral arrangement method, the pushing efficiency and control accuracy in surgery are significantly improved.

[0030] (3) The inner lining layer of the present application adopts a high polymer material with low modulus and low friction coefficient, and completely covers and seals all the distal end through areas through a thermal re-lining process, which not only ensures the fluid tightness of the microcatheter lumen to prevent leakage of contrast agent or drugs, but also provides an extremely smooth inner surface, greatly reducing the resistance of the guide wire and delivery instrument; compared with the existing catheter without an inner lining or with a high modulus inner lining, the present application has excellent delivery performance and smooth operation while maintaining ultra-high flexibility.

[0031] (4) The outer tube component and the inner lining layer of the present application are combined with high polymer materials with a significant difference in modulus, and the modulus of the outer tube is much higher than that of the inner lining, with a modulus ratio of more than 5:1. This material gradient design enables the outer tube to have sufficient rigidity and force transmission capacity, while the inner lining layer can fully deform and absorb stress when bending, protecting the notch structure and avoiding interlayer peeling, further enhancing the durability and consistency of the overall structure of the catheter in repeated bending, solving the problem of difficult balance between rigidity and flexibility in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, a brief introduction to the drawings needed to be used in the embodiments or the prior art description will be given below. Obviously, the drawings described below are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings;

[0033] Figure 1 is a schematic diagram of the microcatheter of the present application;

[0034] Figure 2 is a laser etched notch structure and arrangement diagram of the present application.

[0035] In the figure: 1, outer tube component; 2, laser etched notch; 21, proximal non-through area; 22, distal end through area. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0037] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, therefore, the scope of protection of the present application is not limited by the specific embodiments disclosed below.

[0038] In the diagnosis and treatment by minimally invasive intervention technology, microcatheter and microguide wire are usually used in cooperation. The microguide wire is placed in the microcatheter and can slide along the microcatheter. After the position of the lesion area is determined by the microguide wire, the microguide wire is withdrawn, and the microcatheter is used to deliver drugs or micro-treatment devices such as vascular stents to the lesion area. In general, the guide wire goes first, and the catheter goes later. In clinical application, only the microcatheter and the microguide wire cannot completely meet the needs of the operation. For example, in order to improve the positioning accuracy of the lesion area, it is usually necessary to continuously take X-ray to obtain the real-time position of the microcatheter and the microguide wire.

[0039] The blood vessels of the human body are complex, and the cerebral blood vessels present a complex path of "serpentine tortuosity + acute angle turning". The peripheral blood vessels need to cross a serpentine path of tens of centimeters. In order to enable the microcatheter to smoothly pass through such tortuous blood vessels, the existing technology usually etches multiple notches on the wall of the tube to improve flexibility by weakening the local rigidity. However, the existing microcatheter usually adopts symmetrically distributed rectangular notches or spiral notches. On the one hand, if the notches are too deep or too wide, although the flexibility can be improved, the axial rigidity will be excessively weakened, causing the catheter to be easily folded or compressed during pushing; on the other hand, if the notches are too shallow or too narrow, although the rigidity can be maintained, the flexibility requirement of the complex curve cannot be met, and the microcatheter is easily stuck with the blood vessel wall, and even the endothelium of the blood vessel is damaged due to stress concentration.

[0040] In view of the above problems found by the applicant, the applicant improves the structure of the microcatheter and proposes a microcatheter based on laser etching hollow structure. By precisely laser etching the wall of the microcatheter body, a new type of through and non-through notch combined structure with axial functional gradient is constructed, and combined with the circumferential asymmetric arrangement mode and the axial staggered alignment arrangement, the collaborative optimization of the axial thrust transmission efficiency and the local bending flexibility of the microcatheter is realized, and the controllability, passability and surgical safety of the microcatheter in the complex vasculature are significantly improved.

[0041] Figure 1 A schematic diagram of the microcatheter of the present embodiment is shown. The microcatheter comprises an outer tube member 1 and an inner lining layer. The outer tube member 1 serves as the core bearing structure of the microcatheter, and a plurality of laser etching notches 2 are opened on the outer surface thereof. The inner lining layer is continuously provided on the inner wall of the outer tube member 1 and extends along the entire axial length direction thereof to provide a fluid-tight and low-friction inner surface.

[0042] The outer tube member 1 is made of medical grade polymer material, which should have good biocompatibility, mechanical strength and fatigue resistance. In a specific embodiment, the outer tube member 1 is made of polyether block amide (PEBAX 72D) material, with an outer diameter of 1.5 mm and an inner diameter of 1.2 mm. The outer tube member 1 extends along its axial length direction, has a proximal end and a distal end, the proximal end is the user's operating end, and the distal end is the head end of the microcatheter, and the total length of the outer tube member 1 is set according to the clinical application requirements, such as 700 mm.

[0043] Further, the plurality of laser etched notches 2 on the outer surface of the outer tube member 1 are periodically or non-periodically arranged along the axial direction of the outer tube member 1. Each laser etched notch 2 includes a proximal non-penetrating region 21 and a distal penetrating region 22 in the axial direction, and the two regions together form a laser etched notch 2, which ensures that within a single laser etched notch 2, the mechanical properties exhibit a continuous transition from relatively rigid to highly flexible along the axial direction.

[0044] Specifically, the proximal non-penetrating region 21 is rectangular or trapezoidal in shape, serving as the main axial force receiving and transmitting anchor point. The proximal non-penetrating region 21 is a non-penetrating shallow notch region with an etching depth less than the wall thickness of the outer tube member 1, ensuring that there is a continuous tube wall material on the inner wall side of the outer tube member 1, thereby maintaining a high local axial stiffness and effectively resisting local buckling. The proximal non-penetrating region 21 is rectangular in shape, with an etching depth of 30% to 60% of the wall thickness of the outer tube member 1. This parameter configuration allows the proximal non-penetrating region 21 to provide firm support when subjected to axial thrust, while avoiding affecting the fluid tightness of the inner lumen.

[0045] Adjacent to the proximal non-penetrating region 21 is the distal penetrating region 22, which occupies 50% to 60% of the total axial length of the laser etched notch 2. The distal penetrating region 22 serves as the main bending flexibility unit, aiming to minimize the local bending stiffness. The distal penetrating region 22 is a deep notch region that completely penetrates the wall thickness of the outer tube member 1, with an etching depth equal to the wall thickness of the outer tube member 1, i.e. 0.15 mm.

[0046] Further, the distal penetrating region 22 has a symmetric structure with a narrowed middle and expanded ends in cross-sectional shape, and the side close to the proximal non-penetrating region 21 is conformally connected to the proximal non-penetrating region 21, i.e. the two regions smoothly transition at the connection without height difference or gap, together forming a continuous notch structure.

[0047] Specifically, the cross-sectional shape of the distal through region 22 is composed of two mirror-image right-angled trapezoids, forming a dumbbell-like or double-horn-like structure with a narrow opening in the middle and wide openings at both ends. Among them, the right-angle waists of the two right-angled trapezoids are collinear and jointly form a connecting edge shared with the long side of the rectangle of the proximal non-through region 21, ensuring continuous and smooth force flow transmission between the two regions, and the opening length is relatively large; while the upper bases of the two trapezoids are adjacent and jointly form a narrow opening in the middle, and the length of the narrow opening in the middle is significantly smaller than the length of the lower base at both ends. Preferably, the ratio of the length of the narrow opening in the middle to the length of the opening at a single end is in the range of 1:1.5-3. The included angle between the hypotenuse and the base of the right-angled trapezoid (i.e. the wedge angle) is in the range of 20°-45°, which is beneficial to optimize the stress distribution and avoid stress concentration at sharp corners.

[0048] This special through design, by forming a narrow flexible hinge in the middle and keeping larger openings at both ends, achieves multiple beneficial effects: first, while ensuring that the material in this region is completely removed to achieve extreme flexibility, the narrow opening structure in the middle can serve as a more explicit bending fulcrum when the catheter is bent, making the bending behavior more controllable and smoother, and avoiding the disordered twisting that may occur in ordinary rectangular through grooves; second, the wide opening structure expanded at both ends provides more deformation space for bending, further reducing the bending resistance, and helping to reduce the extrusion of the inner lining layer when bending; third, the gradual transition structure from the wide opening to the narrow opening effectively disperses the bending stress and improves the fatigue resistance of this region, so that cracks or structural damage are less likely to occur even after high-frequency repeated bending.

[0049] Figure 2 The laser etched notch structure and arrangement of the present embodiment are shown. A plurality of laser etched notches 2 present a specific arrangement pattern on the outer tube member 1:

[0050] The first arrangement pattern: on a single circumferential layer with N laser etched notches 2, the circumferential angular interval between the center lines of adjacent laser etched notches 2 is not equal. Specifically, at any axial section of the outer tube member 1, the plurality of axial beams (i.e. the solid material parts not etched by the notches) separated by the N laser etched notches 2 are unevenly distributed in the circumferential direction of the outer tube member 1. In one embodiment, at a certain specific axial position, there are three laser etched notches 2 arranged on the circumference of the outer tube member 1, which separate the circumference into three axial beams with different widths. The circumferential angles of the three axial beams are 110°, 210° and 315° respectively. By optimizing the circumferential size and distribution angle of each axial beam, the present invention aims to ensure that the microcatheter has controllable and consistent bending performance in different bending directions, thereby improving its multi-directional passing ability in complex blood vessel networks, effectively dispersing local stress and enhancing fatigue resistance.

[0051] The second arrangement mode: in the continuous 4-6 axial layers, the center line of the laser etching notch 2 between adjacent axial layers has a circumferential angle offset of 5-15°, and in the continuous 4-6 axial layers, the offset direction remains the same (for example, all clockwise or all counterclockwise). After that, in the next continuous 4-6 axial layers, the center line of the laser etching notch 2 between adjacent axial layers also has a circumferential angle offset of 5-15°, but the offset direction is opposite to that in the previous continuous 4-6 axial layers (for example, if the previous layer is clockwise offset, then this layer is counterclockwise offset). After that, the offset mode repeats every 4-6 axial layers.

[0052] This periodic reverse offset arrangement strategy can build a continuous, strong and slightly helical extending axial solid beam network in the outer tube member 1. These solid beams serve as the main force transmission path, ensuring that the axial thrust applied from the proximal end of the microcatheter can be efficiently and low-loss transmitted to the distal end, greatly inhibiting the "accordion effect" caused by local structural instability during pushing. At the same time, this arrangement mode avoids the continuous helical extension of the notches in a single direction, effectively inhibiting the unintended twisting or rotation of the catheter when under stress, significantly enhancing the predictability and precision of the physician's control of the catheter's distal end orientation. In addition, this arrangement allows stress to be dispersed over a longer range of axial solid beams, avoiding excessive concentration of stress at a specific location, thereby further improving the microcatheter's fatigue resistance and structural reliability for long-term use in repeated bending and pushing operations.

[0053] Through the synergistic effect of the above-mentioned first and second arrangement modes, the microcatheter of the present application achieves a comprehensive optimization of axial stiffness, bending flexibility, torsional stability and fatigue resistance, making it better adapt to complex and tortuous vascular anatomical environments and improving the success rate and safety of interventional surgery.

[0054] The inner lining completely covers all the distal through regions 22 on the outer tube member 1, and both the outer tube member 1 and the inner lining are made of high molecular materials, and the modulus of the high molecular material of the inner lining is much lower than that of the outer tube member 1. Specifically, the outer tube member 1, as the main load-bearing and force transmission structure, is made of medical high molecular materials with high stiffness and strength, with a tensile modulus in the range of 500-3000 MPa, preferably greater than 1000 MPa. Suitable materials for the outer tube member 1 include but are not limited to polyether block amide (PEBAX, such as 72D and above hardness grade), polyamide (Nylon), polyimide (Polyimide) or their composite materials. Such materials not only provide the necessary axial compressive stiffness to effectively resist the "accordion effect", but also ensure high machining precision and edge quality during laser etching.

[0055] Further, the inner liner layer, as a sealing and low-friction functional layer, is made of a flexible medical polymer material with low modulus, low friction coefficient and excellent biocompatibility. The material of the inner liner layer includes but is not limited to medical high-density polyethylene (HDPE) or low-hardness polyether block amide (PEBAX, such as 35D-55D hardness grade).

[0056] Further, the ratio of the modulus of the material of the outer tube member 1 to the modulus of the material of the inner liner layer is greater than 5:1. For example, the outer tube member 1 is made of PEBAX 72D with a modulus of about 1200 MPa, and the inner liner layer is made of HDPE with a modulus of about 110 MPa, and the modulus ratio of the two is about 12:1.

[0057] Through the design of the modulus difference between the materials of the outer tube member 1 and the inner liner layer, the present application realizes the synergistic optimization of multiple performances. The high-modulus outer tube member 1 forms a solid main load-bearing structure, ensuring that the proximal non-penetrating region 21 and the axial beam formed by the staggered arrangement can efficiently transfer the axial thrust, greatly avoiding energy dissipation and "accordion effect" during pushing. At the same time, the extremely low modulus of the inner liner layer can cause sufficient elastic deformation when the catheter is bent, not only perfectly adapting to the deformation of the outer tube structure and reducing interlayer shear stress, thereby significantly improving the fatigue resistance, but also completely retaining the ultra-high local flexibility brought by the distal penetrating region 22. In addition, the extremely low friction coefficient of the inner liner layer material also provides a smooth inner lumen surface for the guide wire and the delivery instrument, further reducing the delivery resistance and enhancing the smoothness and controllability of the surgical operation.

[0058] Further, the design of the inner liner layer ensures the complete fluid sealing and low-friction delivery capability of the microcatheter. The continuous, uninterrupted low-modulus inner liner layer provides reliable fluid sealing for all distal penetrating regions 22 on the outer tube member 1, ensuring the airtightness of the microcatheter lumen, so that it can be safely and efficiently used for injection of contrast medium, drugs or embolic agents.

[0059] The present application also provides a preparation method of a microcatheter for preparing the above-mentioned microcatheter, comprising the following steps:

[0060] Step S1, a medical-grade polymer material is used to prepare a pipe material with a predetermined outer diameter, inner diameter and wall thickness by an extrusion process, which is used as the outer tube member 1. The material of the outer tube member 1 is selected from one of polyether block amide, polyamide or polyimide, and the tensile modulus thereof ranges from 500 to 3000 MPa.

[0061] Step S2, the outer tube component 1 obtained in step S1 is clamped on a high-precision rotary and linear motion platform, and a picosecond or femtosecond pulse laser is used to perform first laser etching on the outer surface of the outer tube component 1 in an inert gas protection atmosphere; the overall profile shape of the plurality of laser etching notches 2 is etched by controlling the laser parameters (including wavelength, pulse energy, repetition frequency and scanning speed) and the rotation and feeding of the motion platform, and the etching depth is controlled to be a preset depth (i.e. 30% to 60% of the wall thickness of the outer tube component 1) of the proximal non-penetrating region 21, thereby forming an initial notch.

[0062] Step S3, a second laser etching is performed on the distal end portion of the initial notch formed in step S2; by dynamically adjusting the pulse energy and focusing position of the laser, the etching depth is controlled to be exactly equal to the remaining wall thickness at the position, thereby accurately forming the distal penetrating region 22 and making the region completely penetrate; the second laser etching is also performed in an inert gas protection atmosphere.

[0063] Step S4, a pre-prepared thin-walled tube made of low-modulus flexible high-molecular material is used as an inner lining preform, and is inserted into the inner cavity of the outer tube component 1 after step S3; then, through a hot relining process, the thin-walled tube is caused to heat expand and plastically deform at an accurately controlled temperature (which is higher than the softening point of the inner lining material but lower than the melting point of the material of the outer tube component 1) and an air pressure of 0.1 MPa to 0.4 MPa, so as to tightly fit with the inner wall of the outer tube component 1, thereby forming a complete, continuous and smooth inner lining; the inner lining completely covers and seals all the distal penetrating regions 22, thereby ensuring the fluid tightness of the inner cavity of the microcatheter; the inner lining material is selected from one of medical high-density polyethylene and low-hardness polyether block amide.

[0064] It is worth noting that during the hot relining process, the inner lining thin-walled tube after heat treatment is in a softened or preliminarily molten state, and an inert gas pressure of 0.1 MPa to 0.4 MPa is applied to the inner cavity of the inner lining thin-walled tube. The softened or preliminarily molten inner lining thin-walled tube fills and perfectly seals all the distal penetrating regions 22 under pressure, and through the surface tension effect and accurate temperature control and pressure control, it is ensured that the inner lining thin-walled tube is tightly combined with the inner wall of the outer tube component without causing the inner cavity surface to have protrusions or be not smooth due to excessive flow or accumulation.

[0065] Step S5, the microcatheter integrated with the inner lining is cleaned to remove processing residues; then, the geometry of the notch, the etching depth, the penetration condition, and the covering quality and sealing performance of the inner lining are inspected by using an optical microscope or an endoscope, so as to ensure that the product meets the design requirements.

[0066] Further, in steps S2 and S3, the high-precision motion platform controls the rotation of the outer tube member 1 about its axis and the translation of the outer tube member 1 along its axis according to a preset program, so that the plurality of laser-etched notches 2 are distributed asymmetrically in the circumferential direction and are arranged in a periodically reversed staggered manner in the axial direction. The high-precision motion platform has at least two motion axes: a high-precision rotation axis (for rotation about the tube axis) and a high-precision linear axis (for movement along the tube axis). During installation, the concentricity error between the microcatheter body and the rotation axis of the workbench should be less than ±10 μm, and the axial straightness should be checked to avoid geometric distortion during etching.

[0067] Further, the thermal re-lining process is performed in a heating furnace or by local heating with a hot air gun, and a slight positive pressure of 0.1 MPa to 0.4 MPa can be applied to the inside of the thin-walled tube to assist its expansion and attachment.

[0068] The technical advantages of the microcatheter of the present application are further illustrated by the following examples, comparative examples, and performance data comparison.

[0069] Example 1:

[0070] This example provides a microcatheter according to the present application.

[0071] The outer tube member 1 is made of medical-grade polyether block amide (PEBAX 72D, modulus about 1200 MPa), with an outer diameter of 0.85 mm, an inner diameter of 0.55 mm, and a wall thickness of 0.15 mm.

[0072] A plurality of notches are formed on the outer surface of the outer tube member 1 by laser etching, each notch consisting of a proximal non-penetrating region 21 and a distal penetrating region 22. The proximal non-penetrating region 21 has an etching depth of 0.075 mm, an axial length of 0.4 mm, a width of 0.10 mm, and a rectangular cross-section; the distal penetrating region 22 has an etching depth of 0.15 mm, an axial length of 0.6 mm, and a symmetric structure with a narrowed middle portion and expanded ends, wherein the length of the narrow middle portion is 0.05 mm and the length of the two end openings is 0.15 mm. All notches are arranged asymmetrically in the circumferential direction (4 notches, circumferential intervals of 80°, 100°, 80°, 100°) and in a staggered manner in the axial direction (4 axial layers in a group, with a 10° offset in the same direction within the group and a reversed offset between groups).

[0073] A HDPE inner liner tube with a wall thickness of 0.03 mm and a modulus of about 110 MPa is inserted into the inner cavity of the outer tube member 1 with etched notches, and hot relining is performed at a temperature of 140-155°C, which is higher than the melting point of HDPE, so as to soften or even preliminarily melt the HDPE, but is far lower than the melting point of the PEBAX outer tube member 1, so as to ensure that the outer tube structure remains stable in shape during processing; during this process, a nitrogen pressure of 0.2-0.3 MPa is applied to the inner cavity of the HDPE inner liner tube, so that the inner liner tube is tightly combined with the inner wall of the outer tube member 1 and completely covers all the distal through regions 22, and the microcatheter is formed after cooling and setting.

[0074] Example 2

[0075] This example provides another microcatheter according to the present application.

[0076] The outer tube member 1 of the microcatheter is made of medical-grade Nylon 12 with a modulus of about 1600 MPa, and has the same size as in Example 1.

[0077] The etching depth of the non-through region 21 near the proximal end of the notch is 0.09 mm, and the rest of the notch structure and size are the same as in Example 1. The notches are arranged in a circumferential asymmetric manner (3 notches, spaced 110°, 130°, and 120°) and an axial staggered manner (5 continuous axial layers, with the same direction offset by 8° within the group).

[0078] A PEBAX inner liner tube with a wall thickness of 0.03 mm is inserted into the inner cavity of the outer tube member 1 with etched notches, and hot relining is performed at a temperature of 160-170°C, which is higher than the melting point of HDPE, so as to soften or even preliminarily melt the HDPE, but is lower than the melting point of the Nylon 12 outer tube member 1, so as to ensure that the outer tube structure remains stable in shape during processing; during this process, a nitrogen pressure of 0.25-0.35 MPa is applied to the inner cavity of the PEBAX inner liner tube, so that the inner liner tube is tightly combined with the inner wall of the outer tube member 1 and completely covers all the distal through regions 22, and the microcatheter is formed after cooling and setting.

[0079] Comparative Example 1

[0080] This comparative example provides a conventional spiral groove microcatheter. The outer tube member 1 of the microcatheter is made of the same PEBAX tube material as in Example 1. A continuous, equal-depth, and equal-width spiral groove is formed by laser etching, with a groove width of 0.10 mm, a pitch of 0.8 mm, and an etching depth of 0.12 mm (non-through, with a remaining wall thickness of 0.03 mm). The microcatheter does not have an inner liner.

[0081] Comparative Example 2

[0082] The outer tube member 1, inner liner, and notch shape and size of the microcatheter of this comparative example are exactly the same as in Example 1, but the notches are arranged in a circumferential symmetric manner (4 notches, with a spacing of 90°).

[0083] Comparative Example 3:

[0084] The outer tube member 1 and the slot design and arrangement pattern of the microcatheter of the present comparative example are exactly the same as those of Example 1, but no inner lining layer is integrated.

[0085] The above examples and comparative examples are tested for performance according to the industry standards YY / T 0663.1-2014 and YY / T 1536-2017, including axial thrust transmission efficiency, minimum bending radius, buckling resistance critical load, fluid tightness, guidewire delivery resistance and fatigue life of 10,000 cycles. The results are shown in Table 1.

[0086] Table 1. Comparison of performance test results

[0087]

[0088] The test results show that the microcatheters of Examples 1 and 2 of the present application exhibit significant advantages in axial thrust transmission efficiency, buckling resistance, bending flexibility, fluid tightness, guidewire delivery smoothness and fatigue life. Specifically, the axial thrust transmission efficiency of Example 1 is as high as 92.5%, which is much higher than that of Comparative Example 1 (65.8%), which is due to the efficient force transmission path constructed by the axial staggered arrangement of the proximal non-penetrating region 21 and the distal penetrating region 22, effectively suppressing the "accordion effect". At the same time, its minimum bending radius can reach 1.8 mm, which is significantly better than that of Comparative Example 1 (2.5 mm), proving the key role of the design of the distal penetrating region 22 in improving flexibility. The integrated PTFE inner lining layer ensures fluid tightness and provides extremely low guidewire delivery resistance (0.12 N). Comparative Example 2 has slightly lower axial thrust transmission efficiency and buckling resistance than Example 1 due to the circumferential symmetrical arrangement, indicating the importance of asymmetrical arrangement in optimizing stress distribution and force transmission. Comparative Example 3 has no inner lining layer, although it has good flexibility, but it completely loses the fluid sealing function and has a huge guidewire delivery resistance.

[0089] In summary, the microcatheter based on laser etching hollow structure and the preparation method thereof of the present application synergistically realize the previously difficult to achieve high efficient axial force transmission capacity, excellent bending flexibility, complete fluid tightness and excellent instrument delivery smoothness on a single device, and completely overcome the technical contradictions between the multiple dimensions of the performance of the microcatheter in the prior art, bringing important technical breakthroughs to the field of interventional surgical instruments.

[0090] The application is not limited to the above-mentioned embodiments, and those skilled in the art can make various modifications and variations according to the technical solutions of the application, and all the modifications and variations shall be included in the protection scope of the application. For example, the material of the outer tube member 1 can be selected from other medical polymer materials or alloy materials according to specific application scenarios, such as medical-grade stainless steel, nickel-titanium alloy, etc. The shape, axial length, circumferential width, etching depth and arrangement density of the gradient functional through slot can be adjusted to adapt to different parts and different surgical needs. The material of the inner lining layer can also be selected from other medical polymer materials with similar low modulus and low friction characteristics. All these modifications within the spirit and scope of the application shall be regarded as equivalent embodiments of the application.

Claims

1. A microcatheter based on a laser-etched hollow structure, characterized in that, The microcatheter includes: outer tubular components; An inner lining layer is disposed on the inner wall of the outer tube component; and Multiple laser-etched grooves are formed on the outer surface of the outer tube component, and each laser-etched groove includes, in the axial direction: In the proximal non-through region, the etching depth is less than the wall thickness of the outer tube component; The etching depth of the distal through-area is equal to the wall thickness of the outer tube component; The distal through region has a symmetrical cross-sectional shape that narrows in the middle and expands at both ends, and its side near the proximal non-through region is conformally connected to the proximal non-through region. The inner lining completely covers all of the distal through-areas on the outer tube component.

2. The microcatheter based on a laser-etched hollow structure according to claim 1, characterized in that: On a single circumferential layer having N laser-etched grooves, the circumferential angular intervals between the center lines of adjacent laser-etched grooves are not equal.

3. A microcatheter based on a laser-etched hollow structure according to claim 1, characterized in that: Within 4 to 6 consecutive axial layers, the center line of the laser-etched groove between adjacent axial layers has a circumferential angular offset of 5°-15°, and the offset direction is the same. Within the next 4 to 6 consecutive axial layers, the center line of the laser-etched groove between adjacent axial layers has a circumferential angular offset of 5°-15°, and the offset direction is opposite to that of the previous consecutive axial layer.

4. A microcatheter based on a laser-etched hollow structure according to claim 1, characterized in that: The etching depth of the proximal non-through region is 30% to 60% of the wall thickness of the outer tube component.

5. A microcatheter based on a laser-etched hollow structure according to claim 1, characterized in that: The cross-sectional shape of the distal through area is composed of two mirror-image right-angled trapezoids; wherein the right-angled legs of the two right-angled trapezoids are collinear and together form a connecting side shared with the long rectangular side of the proximal non-through area; the lower bases of the two right-angled trapezoids are located at both ends in the width direction of the slot, and their length is greater than the length of the narrow opening in the middle formed by the upper bases of the two trapezoids.

6. A microcatheter based on a laser-etched hollow structure according to claim 1, characterized in that: The axial length of the proximal non-penetrating region is the same as that of the distal penetrating region.

7. A microcatheter based on a laser-etched hollow structure according to claim 1, characterized in that: Both the outer tube component and the inner lining are made of polymer materials, and the polymer material modulus of the inner lining is much lower than that of the polymer material of the outer tube component.

8. A method for preparing a microcatheter, comprising preparing a microcatheter as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Prepare the outer tube components; S2. Using a laser, the overall outline shape of multiple laser-etched grooves is etched on the outer surface of the outer tube component. The etching depth is controlled to be the preset depth of the near-end non-penetrating region to form an initial groove. S3. In the initial groove formed in step S2, a secondary laser etching is performed on the far end portion, with the etching depth equal to the remaining wall thickness at that position, to form the far end through area and make the area completely through. S4. Integrate the inner liner into the inner wall of the outer tube component, such that the inner liner completely covers and seals all the distal through areas.

9. A method for preparing a microcatheter according to claim 8, characterized in that: In step S4, a pre-prepared flexible polymer thin-walled tube is inserted into the inner cavity of the outer tube component. By applying gas pressure and heat treatment, the thin-walled tube expands and adheres to the inner wall of the outer tube component, forming the inner lining layer.

10. A method for preparing a microcatheter according to claim 9, characterized in that: Both the outer tube component and the inner lining are made of polymer materials, and the melting point of the polymer material in the inner lining is lower than that of the polymer material in the outer tube component.

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