Microcatheter and preparation method thereof
By coaxially welding the imaging ring to the distal end of the braided layer in the microcatheter and setting microgrooves and a platinum-iridium alloy coating at the proximal end of the imaging ring, the problem of rigidity concentration caused by the thickening of the imaging ring is solved, achieving uniformity of the outer diameter and flexibility of the microcatheter and extending its service life.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FUJIAN MEDICAL UNIV UNION HOSPITAL
- Filing Date
- 2026-01-21
- Publication Date
- 2026-05-12
AI Technical Summary
The existing microcatheter imaging ring is thickened, which leads to a sudden increase in rigidity at the distal end of the catheter, resulting in stress concentration during bending and making it prone to fatigue fracture, thus increasing the risk of clinical use of the device.
The developing ring is coaxially welded to the far end of the braided layer through multiple circumferentially distributed first solder points. The outer diameter of the developing ring does not exceed the circumferential outer contour of the braided layer. Microgrooves and a platinum-iridium alloy coating are set on the near end face of the developing ring. Combined with laser welding and liquid nitrogen cooling protection, the outer layer is covered by thermoforming.
It eliminates the sudden increase in the distal outer diameter of the microcatheter, reduces the abrupt change in rigidity in the imaging ring region, prolongs the fatigue life of the interface between the imaging ring and the braided layer, and improves the imaging properties, flexibility, and durability of the microcatheter.
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Figure CN122006064A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of medical device technology, and in particular to a microcatheter and a method for preparing the microcatheter. Background Technology
[0002] In clinical use, there is an inherent contradiction between the radioactivity (X-ray non-transmissive linearity) and the flexibility of the distal end of a microcatheter: Traditional microcatheters use a socketed platinum-iridium alloy radioactive ring, which is fixed to the metal braided layer with adhesive. This design not only increases the outer diameter of the catheter in the radioactive ring area, but also leads to a sudden increase in rigidity at the distal end of the catheter, resulting in stress concentration during bending. The end face where the metal braided layer meets the radioactive ring is prone to fatigue fracture, increasing the risk of the device in clinical use. Summary of the Invention
[0003] The purpose of this invention is to provide a microcatheter and a method for preparing a microcatheter, so as to solve the problems of the fixed thickening of the imaging ring and stress concentration in existing microcatheters.
[0004] To solve the above-mentioned technical problems, the present invention provides a microcatheter comprising: an outer layer, an inner layer, a braided layer, and a radiopaque ring; the outer layer covers the braided layer and the radiopaque ring, and the inner layer is lined within the braided layer and the radiopaque ring; the radiopaque ring is coaxially welded to the distal end of the braided layer through a plurality of circumferentially distributed first solder points; the outer diameter of the radiopaque ring does not exceed the circumferential outer contour range of the distal end of the braided layer.
[0005] Optionally, the proximal end face of the developing ring has a plurality of microgrooves, the depth of which is 10μm to 30μm.
[0006] Optionally, the proximal end face of the developing ring also has a platinum-iridium alloy coating that at least covers the microgroove, the thickness of which is 0.5 μm to 1 μm.
[0007] Optionally, the diameter of the first solder joint is 40μm~60μm.
[0008] Optionally, the microcatheter includes a proximal segment, a transition segment, and a distal segment connected sequentially in the axial direction; the inner diameter of the proximal segment is 0.52±0.1mm, and the length of the proximal segment is 1100mm~1550mm; the inner diameter of the distal segment is 0.40±0.02mm, and the length of the distal segment is 50mm~150mm; the length of the transition segment is 50mm~100mm.
[0009] Optionally, the braided layer is formed by braiding filaments; wherein the intersections of the braided filaments located in the proximal section are connected by a second solder joint; the intersections of the braided filaments located in the transition section are connected by a third solder joint; the diameter of the second solder joint is 180μm~220μm, and the diameter of the third solder joint is 85μm~115μm.
[0010] Optionally, the inner wall of the transition section has micro-spiral guide grooves; the groove depth of the micro-spiral guide grooves is 5μm~15μm, and the pitch is 0.3mm~0.7mm.
[0011] Optionally, the inner layer of the proximal segment is distributed with glass fiber reinforced polyether block amide; the inner layer of the distal segment is distributed with nanodiamond particles.
[0012] Optionally, the outer layer of the proximal segment is made of polyamide with a Shore hardness of 72D to 90D; the outer layer of the transition segment is made of polyether block amide with a Shore hardness of 55D to 74D; and the outer layer of the distal segment is made of polyether block amide with a Shore hardness of 35D to 55D.
[0013] Optionally, the outer layer located in the proximal segment is embedded in the braided layer located in the proximal segment; the outer layer located in the distal segment is distributed with barium sulfate imaging particles.
[0014] To address the aforementioned technical problems, the present invention also provides a method for preparing a microcatheter, which is used to prepare the microcatheter as described above; the method for preparing the microcatheter includes:
[0015] The inner layer is attached to the outside of the mandrel, and the braided layer is fitted over the inner layer;
[0016] The distal ends of the braided filaments of the braided layer are cut into rings, deburred by electrochemical polishing, and multiple turns are welded at the intersections of the braided filaments within a range of 2mm to 10mm from the tail end.
[0017] The developing ring is parallel to the distal end of the braided layer and laser welding is performed under liquid nitrogen cooling protection.
[0018] The outer layer is fitted over the braided layer and the developing ring, and the outer layer is thermoformed.
[0019] In summary, in the microcatheter and its preparation method provided by the present invention, the microcatheter comprises: an outer layer, an inner layer, a braided layer, and a radiopaque ring; the outer layer covers the braided layer and the radiopaque ring, and the inner layer lining the braided layer and the radiopaque ring; the radiopaque ring is coaxially welded to the distal end of the braided layer through a plurality of circumferentially distributed first solder points; the outer diameter of the radiopaque ring does not exceed the circumferential outer contour range of the distal end of the braided layer.
[0020] This configuration, by coaxially welding the imaging ring to the distal end of the braided layer, ensures that the outer diameter of the imaging ring does not exceed the circumferential outer contour of the distal end of the braided layer, eliminating the abrupt increase in the outer diameter of the distal portion of the microcatheter and making the outer diameter of the microcatheter uniform. Furthermore, the flat welding of the imaging ring to the braided layer also reduces abrupt changes in rigidity in the imaging ring area, reduces stress concentration, and improves the fatigue life of the interface between the braided layer and the imaging ring, effectively balancing the imaging properties, flexibility, and durability of the microcatheter. Attached Figure Description
[0021] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention.
[0022] Figure 1 This is a schematic cross-sectional view of the microcatheter according to an embodiment of the present invention.
[0023] Figure 2 This is a schematic diagram of the braided layer in an embodiment of the present invention.
[0024] Figure 3 This is a schematic diagram showing the connection between the braided layer and the developing ring in an embodiment of the present invention.
[0025] Figure 4 This is a schematic diagram of the gradient change of the inner diameter of the microcatheter according to an embodiment of the present invention.
[0026] In the attached diagram: 1-outer layer; 2-woven layer; 3-inner layer; 4-developing ring; 51-first solder joint; 52-second solder joint; 53-third solder joint; 61-proximal section; 62-transition section; 63-distal section; 64-micro-spiral guide groove. Detailed Implementation
[0027] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clarify the explanation of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and may sometimes use different scales.
[0028] As used in this invention, the singular forms “a,” “an,” “one,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; and the term “at least two” is generally used to mean “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature; “one end” and “the other end,” and “proximal end” and “distal end” generally refer to two corresponding parts, which include not only endpoints. Furthermore, the terms "installed," "connected," and "attached," as used in this invention, and the term "set" on one element from another, should be interpreted broadly. They generally only indicate a connection, coupling, cooperation, or transmission relationship between the two elements, which can be direct or indirect through an intermediate element. They should not be construed as indicating or implying a spatial relationship between the two elements, meaning one element can be located inside, outside, above, below, or to one side of another element, unless otherwise explicitly stated. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances. Additionally, directional terms such as above, below, up, down, upward, downward, left, and right are used relative to exemplary embodiments as shown in the figures, with upward or upper directions pointing towards the top of the corresponding figure, and downward or lower directions pointing towards the bottom of the corresponding figure.
[0029] The purpose of this invention is to provide a microcatheter and a method for preparing a microcatheter, to solve the problems of thickened and stress-concentrated imaging rings in existing microcatheters. The following description refers to the accompanying drawings.
[0030] Please refer to Figures 1 to 4 This invention provides a microcatheter comprising: an outer layer 1, an inner layer 3, a braided layer 2, and a radiopaque ring 4; the outer layer 1 covers the braided layer 2 and the radiopaque ring 4, and the inner layer 3 lining the braided layer 2 and the radiopaque ring 4; the radiopaque ring 4 is coaxially welded to the distal end of the braided layer 2 via a plurality of circumferentially distributed first solder points 51; the outer diameter of the radiopaque ring 4 does not exceed the circumferential outer contour range of the distal end of the braided layer 2.
[0031] This configuration, by coaxially welding the imaging ring 4 to the distal end of the braided layer 2, ensures that the outer diameter of the imaging ring 4 does not exceed the circumferential outer contour of the distal end of the braided layer 2, eliminating the abrupt increase in the outer diameter of the distal portion of the microcatheter and making the outer diameter of the microcatheter uniform. Furthermore, the flat welding of the imaging ring 4 to the braided layer 2 also reduces the abrupt change in rigidity in the imaging ring 4 region, reduces the occurrence of stress concentration, and improves the fatigue life of the interface between the braided layer 2 and the imaging ring 4, effectively balancing the imaging properties, flexibility, and durability of the microcatheter.
[0032] In an alternative example, the developing ring 4 is made of a platinum-iridium alloy with a Pt:Ir ratio of 9:1 and a density ≥21 g / cm³. The wall thickness of the developing ring 4 is 0.02 mm to 0.05 mm. The braided layer 2 is formed by weaving several braided wires. The material of the braided wires is 304V stainless steel wire, 316V stainless steel wire, or superelastic nickel-titanium alloy wire, and the wire diameter is preferably 0.01 mm to 0.04 mm.
[0033] The welding of the developing ring 4 to the braided layer 2 is preferably performed using a pulsed fiber laser. In one example, the laser parameters are as follows: wavelength 1070±10nm, pulse width 10ns, energy density 15J / mm², and frequency 1kHz. Argon is used as the shielding gas, with a flow rate of 10L / min. There are 16 first solder joints 51, evenly distributed circumferentially. The diameter of the first solder joints 51 is 40μm~60μm, preferably 50μm.
[0034] Optionally, the proximal end face of the developing ring 4 has multiple microgrooves (not shown), the depth of which is 10μm to 30μm, preferably 20μm. The microgrooves are preferably widely distributed on the proximal end face of the developing ring 4, and their structure enhances the mechanical strength of the first weld point 51 during welding with the braided fibers of the braided layer 2.
[0035] Furthermore, the proximal surface of the developing ring 4 also has a platinum-iridium alloy coating that at least covers the microgrooves, the thickness of which is 0.5 μm to 1 μm. The platinum-iridium alloy coating at least covers the microgrooves, optionally also covering the adjacent area of the microgrooves, and preferably covering the entire proximal surface of the developing ring 4. The platinum-iridium alloy coating can be formed on the proximal surface of the developing ring 4 using a magnetron sputtering process. The platinum-iridium alloy coating improves the welding performance between dissimilar metals (stainless steel / nickel-titanium wire and platinum-iridium alloy), and reduces or prevents microcracks caused by differences in the thermal expansion coefficients of the dissimilar metals.
[0036] It should be noted that the combined design of the microgrooves and the platinum-iridium alloy coating allows the microgrooves to increase the surface area and adhesion of the platinum-iridium alloy coating, effectively improving the metallurgical bond strength during laser welding.
[0037] Please refer to Figure 4Optionally, the microcatheter includes a proximal segment 61, a transition segment 62, and a distal segment 63 connected sequentially in the axial direction; the inner diameter of the proximal segment 61 is 0.52±0.1mm, and the length of the proximal segment 61 is 1100mm~1550mm; the inner diameter of the distal segment 63 is 0.40±0.02mm, and the length of the distal segment 63 is 50mm~150mm; the length of the transition segment 62 is 50mm~100mm. Adaptably, the cone angle of the transition segment 62 is 5°~10°, and the inner diameter of the transition segment 62 gradually transitions from 0.40mm in the distal segment 63 to 0.52mm in the proximal segment 61.
[0038] The microcatheter comprises approximately three segments axially. The proximal segment 61 is relatively long and thick, used for efficient transmission of pushing force. The distal segment 63 is the actual working segment; its relatively thin and short shape facilitates highly compliant passage through tortuous vessels. The inner diameter of the distal segment 63 is 0.40±0.02mm, compatible with 0.014" guidewire insertion. The transition segment 52 has a tapered shape, which balances the microcatheter's pushing performance and distal compliance, reducing pushing force loss. Furthermore, the variable-diameter lumen helps eliminate fluid abruptness, optimizes the flow properties of fluids (such as contrast agents), and reduces flow resistance.
[0039] Optionally, the inner wall of the transition section 62 has a micro-spiral guide groove 64; the groove depth of the micro-spiral guide groove 64 is 5μm~15μm, preferably 10μm; the pitch is 0.3mm~0.7mm, preferably 0.5mm. The micro-spiral guide groove 64 is inclined in the same direction as the cone angle of the transition section 62. If the micro-spiral guide groove 64 can be formed on the inner layer 3 of the transition section 52, its function is to further reduce the flow resistance of the fluid. For example, in the microconductor provided in this embodiment, compared with the transition section 62 without the micro-spiral guide groove 64, the shear stress can be reduced from 0.48Pa to 0.32Pa. Optionally, the micro-spiral guide groove 64 can also be further arranged on the inner wall of the proximal section 61 and / or the distal section 63.
[0040] Reducing shear stress offers an additional benefit: while blood typically doesn't enter the lumen of a microcatheter, it's still possible for blood components to come into contact with it during interventional procedures (e.g., when contrast agents or saline are injected, or when backflow occurs), making it impossible to completely prevent blood components from entering the microcatheter's lumen. Reducing shear stress minimizes fluid stagnation and turbulence, preventing blood components (such as platelets) from depositing and activating on the microcatheter's inner surface even if they do enter, thus lowering the risk of thrombosis.
[0041] Optionally, the braided layer 2 is woven from braided yarns; wherein the intersections of the braided yarns located in the proximal segment 61 are connected by a second solder joint 52; the intersections of the braided yarns located in the transition segment 62 are connected by a third solder joint 53; the diameter of the second solder joint 52 is 180μm~220μm, and the diameter of the third solder joint 53 is 85μm~115μm. Optionally, the intersections of the braided yarns located in the distal segment 63 are connected by a first solder joint 51.
[0042] Not all intersections of the braided filaments need to be welded; welding can be selectively performed at certain locations to prevent the filaments from becoming tangled. The second weld point 52, located relatively proximally, is used for high-strength fixation of the braided filaments and can withstand significant pushing forces. The first weld point 51, located relatively distally, has a smaller diameter, providing higher flexibility and reducing rigidity. The third weld point 53, located between the first and second weld points 51, is used to smooth the transition of stress gradient changes. Thus, from proximity to distality, the diameters of the second weld point 52, the third weld point 53, and the first weld point 51 decrease sequentially, adapting to the stress gradient changes required by the microcatheter.
[0043] Optionally, the outer layer 1 located in the proximal segment 61 is made of polyamide with a Shore hardness of 72D~90D; the outer layer 1 located in the transition segment 62 is made of polyether block amide with a Shore hardness of 55D~74D; and the outer layer 1 located in the distal segment 63 is made of polyether block amide with a Shore hardness of 35D~55D. The different hardnesses and materials of the outer layer 1 are adapted to the stress gradient changes required by the microcatheter. The inner layer 3 is preferably made of polytetrafluoroethylene.
[0044] Optionally, the inner layer 3 located in the proximal segment 61 is distributed with glass fiber reinforced polyether block amide; the amount of glass fiber reinforced polyether block amide added can be selected as about 10% (mass percentage), preferably evenly distributed in the material of the inner layer 3 of the proximal segment 61. The inner layer 3 located in the distal segment 63 is distributed with nanodiamond particles. The amount of nanodiamond particles added can be selected as about 5% (mass percentage), and the particle size of the nanodiamond particles can be selected as about 50 nm. The outer layer 1 located in the distal segment 63 is distributed with barium sulfate developing particles, and the amount of barium sulfate developing particles added can be selected as 0~40% (mass percentage).
[0045] Optionally, the outer layer 1 located in the proximal segment 61 is embedded in the braided layer 2 located in the proximal segment 61; that is, the outer layer 1 and the braided layer 2 of the proximal segment 61 form a composite structure. During the fabrication of the microcatheter (see description below), the braided layer 2 is placed between the outer layer 1 and the inner layer 3, and the polyamide material of the outer layer 1 can be melted and embedded in the braided layer 2 through thermoforming. This design can further enhance the delivery strength and rigidity of the microcatheter while maintaining structural integrity.
[0046] The present invention also provides a method for preparing a microcatheter, which is used to prepare the microcatheter as described above; the method for preparing the microcatheter includes:
[0047] Step S1: Attach the inner layer 3 to the outside of the mandrel, and fit the braided layer 2 over the inner layer 3;
[0048] Step S2: Cut the distal end of the braided filaments of the braided layer 2 into a ring shape, electrochemically polish to remove burrs, and weld multiple turns at the intersection of the braided filaments within a range of 2mm to 10mm from the tail end (distal end).
[0049] Step S3: The developing ring 4 is parallel to the distal end of the braided layer 2, and laser welding is performed under liquid nitrogen cooling protection. Here, liquid nitrogen micro-spray cooling is preferred, with a flow rate of 0.1 L / min, synchronized with the laser pulse, to compress the heat-affected zone (HAZ) to below 1 μm, improving the material property retention rate of the braided filaments. During welding, the weld point temperature is preferably monitored in real time using an infrared thermal imager, and the laser energy is dynamically adjusted.
[0050] Step S4: The outer layer 1 is fitted over the braided layer 2 and the developing ring 4, and the outer layer 1 is thermoformed. The thermoforming process preferably uses segmented heating (200°C at the distal end and 160°C at the proximal end), pressure 0.3MPa-0.5MPa, and thermorheological rate: 5mm / min~7mm / min.
[0051] Optionally, prior to step S3, the method for preparing the microcatheter further includes:
[0052] Step S01: Laser etching microgrooves are used to etch microgrooves on the near end face of the developing ring 4, followed by plasma cleaning and activation;
[0053] Step S02: Apply a platinum-iridium alloy coating to the near end face of the developing ring 4 using a magnetron sputtering process.
[0054] Optionally, after step S4, the method for preparing the microcatheter further includes:
[0055] Step S5: Dip the distal end of the microcatheter into a hydrophilic coating, such as PVP, preferably with a dipping length of 400mm to 800mm.
[0056] In summary, in the microcatheter and its fabrication method provided by this invention, the microcatheter comprises: an outer layer, an inner layer, a braided layer, and a radiopaque ring; the outer layer covers the braided layer and the radiopaque ring, and the inner layer lining the braided layer and the radiopaque ring; the radiopaque ring is coaxially welded to the distal end of the braided layer via multiple circumferentially distributed first weld points; the outer diameter of the radiopaque ring does not exceed the circumferential outer contour range of the distal end of the braided layer. This configuration, by coaxially welding the radiopaque ring to the distal end of the braided layer, ensures that the outer diameter of the radiopaque ring does not exceed the circumferential outer contour range of the distal end of the braided layer, eliminating the abrupt increase in the outer diameter of the distal portion of the microcatheter and making the outer diameter of the microcatheter uniform. Furthermore, the flat welding of the radiopaque ring and the braided layer also reduces the abrupt change in rigidity in the radiopaque ring region, reduces stress concentration, and improves the fatigue life of the interface between the braided layer and the radiopaque ring, effectively balancing the radiopaqueness, flexibility, and durability of the microcatheter.
[0057] It should be noted that the above embodiments can be combined with each other. The above description is only a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the present invention.
Claims
1. A microcatheter, characterized in that, include: Outer layer, inner layer, braided layer and developing ring; The outer layer covers the braided layer and the developing ring, and the inner layer is lined within the braided layer and the developing ring; the developing ring is coaxially welded to the far end of the braided layer through a plurality of circumferentially distributed first solder points; the outer diameter of the developing ring does not exceed the circumferential outer contour range of the far end of the braided layer.
2. The microcatheter according to claim 1, characterized in that, The proximal end face of the developing ring has multiple microgrooves, the depth of which is 10μm~30μm.
3. The microcatheter according to claim 2, characterized in that, The proximal end face of the developing ring also has a platinum-iridium alloy coating that at least covers the microgroove, the thickness of which is 0.5 μm to 1 μm.
4. The microcatheter according to claim 1, characterized in that, The diameter of the first solder joint is 40μm~60μm.
5. The microcatheter according to claim 1, characterized in that, The microcatheter includes a proximal segment, a transition segment, and a distal segment connected sequentially in the axial direction; the inner diameter of the proximal segment is 0.52±0.1mm, and the length of the proximal segment is 1100mm~1550mm; the inner diameter of the distal segment is 0.40±0.02mm, and the length of the distal segment is 50mm~150mm; the length of the transition segment is 50mm~100mm.
6. The microcatheter according to claim 5, characterized in that, The braided layer is woven from braided yarns; wherein the intersections of the braided yarns located in the proximal section are connected by a second solder joint; the intersections of the braided yarns located in the transition section are connected by a third solder joint; the diameter of the second solder joint is 180μm~220μm, and the diameter of the third solder joint is 85μm~115μm.
7. The microcatheter according to claim 5, characterized in that, The inner wall of the transition section has micro-spiral guide grooves; the groove depth of the micro-spiral guide grooves is 5μm~15μm, and the pitch is 0.3mm~0.7mm.
8. The microcatheter according to claim 5, characterized in that, The inner layer of the proximal segment is distributed with glass fiber reinforced polyether block amide; the inner layer of the distal segment is distributed with nanodiamond particles.
9. The microcatheter according to claim 5, characterized in that, The outer layer of the proximal segment is made of polyamide with a Shore hardness of 72D to 90D; the outer layer of the transition segment is made of polyether block amide with a Shore hardness of 55D to 74D; and the outer layer of the distal segment is made of polyether block amide with a Shore hardness of 35D to 55D.
10. The microcatheter according to claim 9, characterized in that, The outer layer located in the proximal segment is embedded with the braided layer located in the proximal segment; the outer layer located in the distal segment is distributed with barium sulfate imaging particles.
11. A method for preparing a microcatheter, characterized in that, Used to prepare microcatheters according to any one of claims 1 to 10; The method for preparing the microcatheter includes: The inner layer is attached to the outside of the mandrel, and the braided layer is fitted over the inner layer; The distal ends of the braided filaments of the braided layer are cut into rings, deburred by electrochemical polishing, and multiple turns are welded at the intersections of the braided filaments within a range of 2mm to 10mm from the tail end. The developing ring is parallel to the distal end of the braided layer and laser welding is performed under liquid nitrogen cooling protection. The outer layer is fitted over the braided layer and the developing ring, and the outer layer is thermoformed.