A novel magnetic guidewire with variable stiffness tip and method of making same

Abstract

This invention discloses a novel magnetic guidewire with a variable stiffness tip and its preparation method, belonging to the field of medical device technology. The magnetic guidewire includes a guidewire body, a magnetically controlled tip, and a spring coil. The guidewire body comprises a core wire and an outer layer. One end of the core wire is connected to the spring coil, and the end of the spring coil furthest from the core wire is connected to the magnetically controlled tip. The core wire and the spring coil are embedded together inside the magnetically controlled tip. The spring coil is a continuous spring with a gradually changing stiffness distribution along the axial direction, consisting of an unstretched section, a transition section, and a stretched section. The preparation method includes guidewire body pretreatment, spring coil treatment and fixation, magnetically controlled tip forming, and post-treatment. This invention solves the problems of uneven stiffness transition, easy slippage of the magnetically controlled tip, and susceptibility to puncture by the core wire in conventional magnetic guidewires. It achieves a natural and smooth stiffness transition, improves vascular permeability and connection stability, has a simple preparation process, good biocompatibility, and is suitable for vascular interventional surgery.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a novel magnetic wire with a variable stiffness end and its preparation method. Background Technology

[0002] Magnetically controlled guidewires are key instruments in interventional vascular surgery, widely used in the diagnosis and treatment of tortuous and complex vascular diseases such as cerebrovascular diseases. Their performance directly affects the safety and effectiveness of the procedure. A typical magnetically controlled guidewire usually consists of a magnetically controlled tip and a guidewire body (see appendix). Figure 1 The guidewire body typically consists of two parts: a core wire and a TPU outer layer (or other equivalent alternative materials). The magnetically controlled tip is usually made of soft, magnetically doped silicone. The guidewire body and the magnetically controlled tip are usually directly connected and integrated through the core wire.

[0003] The flexibility of the magnetically controlled tip ensures excellent magnetic response characteristics, meaning it can quickly respond and deform under the influence of an external magnetic field, thereby achieving steering and positioning within the blood vessel. However, there is a significant technical defect in the existing technology: the stiffness difference between the flexibility of the magnetically controlled tip and the high-rigidity metal core wire is too large. This uneven stiffness transition can seriously affect the passage of the magnetic guidewire in blood vessels, especially when dealing with tortuous and complex cerebral blood vessels. Often, the magnetically controlled tip can successfully enter the intended blood vessel, but the main body of the guidewire, due to its high stiffness, cannot deform with the magnetically controlled tip and is difficult to follow, significantly increasing the difficulty and risk of the operation.

[0004] Meanwhile, due to the thin diameter of the core wire, typically only 0.1-0.2 mm, the contact area between the core wire and the magnetic control tip is small, resulting in insufficient interfacial bonding and a risk of the magnetic control tip slipping during surgical procedures. Furthermore, in actual clinical practice, the thin core wire may puncture the epidermis of the magnetic control tip, causing damage and leakage of magnetic materials, further affecting surgical safety and the lifespan of the magnetic guide wire.

[0005] Currently, there is no effective solution to the aforementioned technical problems of uneven stiffness transition, easy slippage of the magnetic control end, and easy puncture. Therefore, this invention proposes a new type of magnetic wire that can achieve smooth stiffness transition, firm connection, and safe use. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of conventional magnetic guide wires in the prior art, such as uneven stiffness transition, easy slippage of the magnetically controlled end, and easy puncture by the core wire. It provides a novel magnetic guide wire with a variable stiffness end and its preparation method. Through structural improvement, the stiffness transition is made natural and smooth, which improves the passability of the magnetic guide wire in tortuous blood vessels. At the same time, it enhances the connection stability between the core wire and the magnetically controlled end, avoids slippage and puncture of the magnetically controlled end, and ensures surgical safety.

[0007] A novel magnetic guide wire with a variable stiffness end, the guide wire body includes a core wire, an outer layer covering the outside of the core wire and a magnetically controlled end, and also includes a spring coil, one end of the core wire is connected to the spring coil, and the core wire and the spring coil are connected together to the magnetically controlled end; The spring coil is a continuous spring with its stiffness gradually distributed along the spring axis. The spring coil includes an unstretched section, a transition section and a stretched section in sequence along the axial direction. The unstretched section is close to the magnetic control end, the stretched section is close to the core wire, and the transition section is between the unstretched section and the stretched section. Furthermore, the bending stiffness of the unstretched section is less than that of the stretched section, and the bending stiffness of the unstretched section is greater than that of the magnetically controlled end, while the bending stiffness of the stretched section is less than that of the core wire.

[0008] Furthermore, the pitch of the stretched section is greater than that of the unstretched section, and the pitch of the transition section is gradually distributed.

[0009] Furthermore, the core wire is a nickel-titanium alloy wire with a diameter of 0.1-0.2 mm; the spring coil is a biocompatible metal spring with a diameter of 0.4 mm in its unstretched state, and the spring coil is coiled layer by layer on the core wire.

[0010] Furthermore, the spring coil and the core wire are bonded and fixed together with medical adhesive, which has good biocompatibility and bonding strength.

[0011] Furthermore, the outer layer of the guidewire body is a TPU outer layer or other biocompatible equivalent material.

[0012] A method for preparing the above-mentioned novel magnetic wire with variable stiffness end includes the following steps: S1: Pre-processing the guide wire body: Take a conventional magnetic guide wire, peel off the outer layer of the guide wire body to expose a section of core wire, and the length of the exposed core wire matches the length of the stretching section of the spring coil; S2: Spring Coil Processing and Fixing: Take a whole continuous spring and stretch it while leaving a part of the unstretched section, so that the spring forms a structure of "unstretched section-transition section-stretched section". Then, tightly fit the stretched section of the spring coil onto the exposed core wire in step 1, and use medical glue to bond and fix the stretched section to the core wire. S3: Magnetically controlled end forming: Insert one end of the core wire connected to the spring coil in step 2 into the polytetrafluoroethylene tube mold, inject the silicone material doped with magnetic particles into the polytetrafluoroethylene tube mold, so that the silicone material completely covers the unstretched section and transition section of the spring coil, as well as the end of the core wire; then put the polytetrafluoroethylene tube mold containing the silicone material into an oven and bake to cure. S4: Post-processing: Remove the PTFE tube mold to obtain a pre-formed new magnetic wire; then magnetize the magnetic control end to obtain the final new magnetic wire with variable stiffness end.

[0013] Furthermore, in step 3, the silicone material doped with magnetic particles is PDMS doped with magnetic particles, and the mass ratio of magnetic particles to PDMS is 1:(1.2~5); if other silicone materials are selected, the doping ratio of magnetic particles can be adjusted adaptively according to the material characteristics.

[0014] Furthermore, in step 3, the baking temperature of the oven is 70-80℃, and the baking time is 1.5-2.5 hours.

[0015] The beneficial effects of this invention are as follows: 1. Achieving smooth stiffness transition and improving vascular permeability: This invention uses a variable stiffness spring coil between the core wire and the magnetically controlled end. The bending stiffness of the unstretched section, transition section, and stretched section of the spring coil increases sequentially, with the stiffness of the unstretched section being greater than that of the magnetically controlled end and the stiffness of the stretched section being less than that of the core wire. This results in a natural and smooth transition of stiffness changes in each part of the novel magnetic guide wire end. It retains the flexibility of the magnetically controlled end to achieve rapid and accurate magnetic response deflection, while ensuring that the guide wire body follows the magnetically controlled end smoothly. This effectively solves the problem of the guide wire body being unable to follow due to the uneven stiffness transition of conventional magnetic guide wires, and is especially suitable for tortuous and complex cerebrovascular interventional surgeries.

[0016] 2. Enhanced connection stability and prevention of magnetron slippage: The spring coils are wound layer by layer on the core wire, significantly increasing the contact area with the core wire. At the same time, the winding structure of the spring coils increases the contact area with the magnetron end. During the injection molding process of the magnetron end, PDMS can fully fill the gaps of the spring coils to form a firm interlocking structure, effectively preventing the magnetron end from slipping off the core wire and improving the reliability of the magnetic wire.

[0017] 3. Preventing the core wire from piercing the magnetic control tip and improving safety: The diameter of the spring coil when it is not stretched is about 0.4mm. Its larger diameter and curved coil shape can effectively wrap and buffer the core wire, preventing the thinner core wire from directly contacting the magnetic control tip and piercing its surface. This prevents damage to the magnetic control tip and leakage of magnetic materials, ensuring surgical safety and the service life of the magnetic guide wire.

[0018] 4. Simple preparation process and low cost: The novel magnetic wire of this invention can be prepared by simple modification based on conventional magnetic wire. The preparation steps are simple and convenient, which can effectively reduce production costs. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a cross-sectional view of a conventional magnetic wire; Figure 2 The conventional guidewire body cannot deform with the magnetically controlled tip; Figure 3 This is a cross-sectional view of the novel magnetic guide wire of the present invention; Figure 4 This is a schematic diagram showing the gradual change in stiffness of the spring coil; Figure 5 For comparison of bending stiffness, the stiffness of the unstretched spring coil is less than that of the stretched spring coil. Figure 6 The new type of magnetic guide wire can achieve deflection of the main body of the guide wire under the drive of the magnetically controlled end; Figure 7 This is a schematic diagram of the pitch of the unstretched section, transition section, and stretched section of the spring coil; Figure 8 The demonstration showed a conventional magnetic wire getting stuck at a bend in a blood vessel due to a sudden change in stiffness, while the novel magnetic wire smoothly passed through the bend thanks to a variable stiffness spring coil. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] A novel magnetic guide wire with a variable stiffness end is provided. The main body of the guide wire includes a core wire 1, an outer layer 2 (preferably a TPU outer layer, but other biocompatible equivalent materials can also be selected) covering the outside of the core wire 1, and a magnetically controlled end 3.

[0023] It also includes a spring coil 4, one end of the core wire 1 is connected to the spring coil 4, and the end of the spring coil 4 away from the core wire 1 is connected to the magnetic control end. The core wire 1 and the spring coil 4 are embedded together inside the magnetic control end 3 to achieve fixed integration of the three.

[0024] Spring coil 3 is a continuous spring with its stiffness gradually varying along the spring axis. Spring coil 3 includes an unstretched section 41, a transition section 42, and a stretched section 43. The densely packed areas of spring coil 4 are the unstretched sections, the sparsely packed areas are the stretched sections, and the transition sections are between the unstretched and stretched sections. The bending stiffness of the unstretched section is less than that of the stretched section, and the bending stiffness of the unstretched section is greater than that of the magnetically controlled end. The bending stiffness of the stretched section is less than that of the core wire. The pitch of the stretched section 43 is greater than that of the unstretched section 41, and the pitch of the transition section 42 is gradually distributed.

[0025] The magnetron end 3 is made of silicone material doped with magnetic particles, preferably PDMS (polydimethylsiloxane) doped with magnetic particles. The magnetic particles are selected from any one or any combination of neodymium iron boron magnetic powder, iron tetroxide powder or pure iron powder. The particle size range of the magnetic particles is 2.6 to 150 micrometers, which ensures that the magnetron end has excellent magnetic response characteristics and can quickly respond and deform under the action of an external magnetic field.

[0026] The core wire 1 is a nickel-titanium alloy wire with good biocompatibility and toughness, and its diameter is 0.1-0.2mm. The spring coil is a biocompatible metal spring with a diameter of about 0.4mm in its unstretched state. The spring coil is coiled layer by layer on the core wire to increase the contact area with the core wire. At the same time, the coiled structure of the spring coil can increase the contact area with the magnetic control end and improve the connection stability.

[0027] The spring coil 4 and the core wire 1 are bonded and fixed together with medical adhesive. The medical adhesive has good biocompatibility and bonding strength, ensuring that the spring coil and the core wire are firmly connected and not easy to fall off.

[0028] The above-mentioned method for preparing novel magnetic wires A method for preparing a novel magnetic wire with a variable stiffness end includes the following steps: Step 1: Pre-processing the guide wire body: Take a conventional magnetic guide wire and peel off the TPU outer layer 2 (or other form of outer layer) on the outside of the guide wire body to expose a section of core wire 1. The length of the exposed core wire 1 matches the length of the stretching section of the spring coil 4 to ensure that the spring coil 4 can be stably sleeved later.

[0029] Step 2: Spring Coil Processing and Fixing: Take a continuous spring and stretch it while leaving a portion of the unstretched section, so that the spring forms a structure of "unstretched section - transition section - stretched section". Then, tightly fit the stretched section of the spring coil onto the exposed core wire in Step 1, and use medical glue to bond and fix the stretched section to the core wire, ensuring that the bond is firm and there is no looseness.

[0030] The degree of spring tension can be adjusted according to actual needs to ensure that the bending stiffness of the tensioned section is less than that of the core wire, the bending stiffness of the untensioned section is greater than that of the magnetically controlled end, and the transition section achieves a smooth transition of stiffness.

[0031] Step 3: Magnetron Terminal 3 Forming: Insert one end of the core wire 1, which was connected to the spring coil in Step 2, into the PTFE tube mold. Inject PDMS (or other equivalent silicone material) doped with magnetic particles into the PTFE tube mold, ensuring that the PDMS completely covers the unstretched and transition sections of the spring coil, as well as the end of the core wire. Then, place the PTFE tube mold containing PDMS into a 75℃ oven and bake for 2 hours to ensure complete curing and forming of the magnetron terminal. The oven temperature can be adjusted within the range of 70-80℃, and the baking time can be adjusted within the range of 1.5-2.5 hours to ensure complete curing of the PDMS without affecting the magnetic properties of the magnetic particles or the biocompatibility of the material.

[0032] In PDMS doped with magnetic particles, the mass ratio of magnetic particles to PDMS is 1:(1.2~5). If the ratio is lower than this, it may lead to insufficient magnetic response, while if the ratio is higher, it will result in the magnetron tip being too hard and difficult to deflect. This ensures that the magnetron tip has good magnetic response performance while guaranteeing its flexibility and toughness. If other silicone materials are selected, the doping ratio of magnetic particles can be adjusted adaptively according to the material characteristics.

[0033] Step 4: Post-processing: Remove the PTFE tube mold to obtain a pre-formed new magnetic wire; then magnetize the magnetic control end to give it magnetic response capability, and finally obtain a new magnetic wire with variable stiffness end.

[0034] The novel magnetic wire prepared in this embodiment has a smooth stiffness transition, a firm connection at the magnetically controlled end, no slippage or damage, and a sensitive magnetic response, which can meet the requirements for use in cerebrovascular interventional surgery.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A novel magnetic guide wire with a variable stiffness end, the guide wire body comprising a core wire (1), an outer layer (2) covering the outside of the core wire (1), and a magnetically controlled end (3), characterized in that: It also includes a spring coil (4), one end of the core wire (1) is connected to the spring coil (4), and the core wire (1) and the spring coil (4) are connected together to the magnetic control end (3); The spring coil (4) is a continuous spring with a gradually varying stiffness along the spring axis. The spring coil (4) includes an unstretched section (41), a transition section (42), and a stretched section (43) along the axial direction. The unstretched section (41) is close to the magnetic control end (3), the stretched section (43) is close to the core wire (1), and the transition section (42) is between the unstretched section (41) and the stretched section (43).

2. The novel magnetic wire with variable stiffness end according to claim 1, characterized in that: The bending stiffness of the unstretched section (41) is less than that of the stretched section (43), and the bending stiffness of the unstretched section (41) is greater than that of the magnetically controlled end (3). The bending stiffness of the stretched section (43) is less than that of the core wire (1).

3. The novel magnetic wire with variable stiffness end according to claim 1, characterized in that: The pitch of the stretched section (43) is greater than that of the unstretched section (41), and the pitch of the transition section (42) is gradually distributed.

4. The novel magnetic wire with variable stiffness end according to claim 1, characterized in that: The core wire (1) is a nickel-titanium alloy wire with a diameter of 0.1-0.2 mm; the spring coil (4) is a biocompatible metal spring with a diameter of 0.4 mm in its unstretched state, and the spring coil (4) is coiled layer by layer on the core wire (1).

5. The novel magnetic wire with variable stiffness end according to claim 1, characterized in that: The spring coil (4) and the core wire (1) are bonded and fixed together by medical adhesive, which has good biocompatibility and bonding strength.

6. The novel magnetic wire with variable stiffness end according to claim 1, characterized in that: The outer layer (2) of the guidewire body (1) is a TPU outer layer (2) or other biocompatible equivalent materials.

7. A method for preparing a novel magnetic wire with a variable stiffness end as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: Pre-processing the guide wire body (1): Take a conventional magnetic guide wire, peel off the outer layer (2) on the outside of its guide wire body (1) to expose a section of core wire (1), and the length of the exposed core wire (1) matches the length of the stretching section (43) of the spring coil (4); S2: Spring Coil (4) Processing and Fixing: Take a whole continuous spring and stretch it while keeping a part of the unstretched section (41) so that the spring forms a structure of "unstretched section (41) - transition section (42) - stretched section (43)". Then, tightly fit the stretched section (43) of the spring coil (4) onto the exposed core wire (1) in step 1, and use medical glue to bond and fix the stretched section (43) to the core wire (1). S3: Magnetically controlled end (3) forming: Insert one end of the core wire (1) connected to the spring coil (4) in step 2 into the polytetrafluoroethylene tube mold, inject the silicone material doped with magnetic particles into the polytetrafluoroethylene tube mold, so that the silicone material completely covers the unstretched section (41) and transition section (42) of the spring coil (4), as well as the end of the core wire (1); then put the polytetrafluoroethylene tube mold containing the silicone material into the oven and bake to cure. S4: Post-processing: Remove the polytetrafluoroethylene tube mold to obtain a preliminary-formed new magnetic wire; then magnetize the magnetic control end (3) to obtain the final new magnetic wire with variable stiffness end.

8. The preparation method according to claim 7, characterized in that: In step 3, the silicone material doped with magnetic particles is PDMS doped with magnetic particles, and the mass ratio of magnetic particles to PDMS is 1:(1.2~5). If the ratio is lower than this, it may lead to insufficient magnetic response, and if the ratio is higher than this, it will lead to the magnetron tip being too hard and difficult to deflect. If other silicone materials are selected, the doping ratio of magnetic particles can be adjusted adaptively according to the material characteristics.

9. The preparation method according to claim 7, characterized in that: In step 3, the baking temperature of the oven is 70-80℃, and the baking time is 1.5-2.5 hours.

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