An interventional soft catheter with a stiffness gradient and a method of making the same

Abstract

The present application relates to an interventional soft catheter with a stiffness gradient and a preparation method thereof, the preparation method comprising the following steps: preparing a catheter mold; preparing an interventional soft catheter with a single stiffness catheter head; performing catheter head processing; performing catheter head multi-stiffness processing to obtain a soft structure with a stiffness gradient; connecting the soft structure with a stiffness gradient with a catheter body and extending into a driving wire to obtain an interventional soft catheter with a stiffness gradient. The interventional soft catheter with a stiffness gradient comprises a catheter head, a catheter body and a driving wire; the catheter head is in interference fit with the catheter body; and the driving wire extends into a through hole of the catheter head. Compared with the prior art, the interventional soft catheter of the present application is a soft medical instrument integrating a soft head and capable of self-bending, and during treatment, a doctor can control the movement of the catheter through a host computer, thereby ensuring the safety of the doctor and greatly improving the treatment efficiency of minimally invasive surgery.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to an interventional soft catheter with a stiffness gradient and its preparation method. Background Technology

[0002] For over a decade, cardiovascular diseases have been a persistent threat to human health. In 2019, the World Health Organization (WHO) reported that cardiovascular and cerebrovascular diseases ranked among the leading causes of death globally, characterized by high mortality and low post-operative survival rates. Current treatments primarily rely on minimally invasive surgery, utilizing medical catheters and guidewires inserted through incisions into blood vessels and delivered to the lesion site under radiological guidance. However, this approach still has limitations. Traditional medical catheters require custom-made tips of varying shapes to accommodate different intravascular environments; the tips of guidewires are uncontrollable within the body, making it difficult to address complex lesions and, once reached, to deploy coils, stents, or other implants in stable positions; rigid medical catheters can damage blood vessels during intravascular procedures. Therefore, developing a safe and effective minimally invasive surgical medical catheter is crucial for addressing these cardiovascular diseases.

[0003] Therefore, there is an urgent need for an interventional soft catheter with a flexible tip and a stiffness gradient that can bend on its own, in order to reduce the complexity of minimally invasive surgery and to deal with more complex lesions. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art by providing an interventional soft catheter with a stiffness gradient and its preparation method. The tip of the interventional soft catheter with a stiffness gradient has a soft structure made of a super-elastic soft material, which provides higher safety when interacting with the fragile internal structure of the human body. Furthermore, the catheter tip can be actively bent through a wire-driven method, giving the catheter greater degrees of freedom to address the problem of reduced mobility when the catheter penetrates the human body. The stiffness of one side of the catheter tip is similar to that of the catheter body, and its stiffness varies with a gradient along the axis. This characteristic of stiffness gradient variation ensures that the curvature of the catheter tip changes uniformly when bent, preventing abrupt changes that could scratch or damage the inner wall of the blood vessel.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] The first objective of this invention is to provide a method for preparing an interventional soft catheter with a stiffness gradient, the method comprising the following steps:

[0007] S1. Prepare a catheter mold according to the structural dimensions of the required interventional soft catheter;

[0008] S2. Using the catheter mold prepared in S1, prepare an interventional soft catheter with a single stiffness catheter tip;

[0009] S3. The single-stiffness catheter tip of the interventional soft catheter prepared in S2 is processed to obtain the processed interventional soft catheter.

[0010] S4. Using the catheter mold prepared in S1, perform multi-stiffness treatment on the catheter tip of the treated interventional soft catheter obtained in S3 to obtain a soft structure with stiffness gradient.

[0011] S5. Connect the soft structure with stiffness gradient obtained in step S4 to the catheter body and extend it into the drive line to obtain the interventional soft catheter with stiffness gradient.

[0012] Furthermore, the preparation of the catheter mold in step S1 includes the following sub-steps:

[0013] S11. Based on the structural dimensions of the required interventional soft catheter, prepare the corresponding first glass plate and glass rod, wherein the thickness of the first glass plate is the same as the radius of the interventional soft catheter, and the diameter of the glass rod is the same as the diameter of the interventional soft catheter.

[0014] S12. Attach the glass rod described in step S11 to the glass slide, and then attach the first glass slide described in step S11 to both sides of the glass rod.

[0015] S13. Cut four second glass sheets according to the glued dimensions, so that the four second glass sheets can just surround the first glass sheet and glass rod in S12 and form a closed cavity to obtain the master mold.

[0016] S14. After covering all surfaces of the master mold with the release agent, let it stand for 30 minutes.

[0017] S15. Mix the conduit mold material in a certain proportion and stir thoroughly to make it evenly mixed;

[0018] S16. Place the well-mixed conduit mold material into a vacuum pump to remove air bubbles, and carefully inject it into the master mold to prevent air bubbles from forming. Then use a blade to scrape off the material that overflows from the master mold.

[0019] S17. After heat treatment of the master mold to solidify the conduit mold material, remove it and demold it to obtain the conduit mold.

[0020] Furthermore, the catheter mold includes two correspondingly arranged catheter mold halves.

[0021] Furthermore, the preparation of the interventional soft catheter at the single-stiffness catheter tip in step S2 includes the following sub-steps:

[0022] S21. Based on the structural dimensions of the required interventional soft catheter, prepare a corresponding porous glass tube, wherein the diameter of the porous glass tube is the same as the diameter of the interventional soft catheter.

[0023] S22. Fix the metal rod in the corresponding through hole in the porous glass tube in step S21, and fix a porous glass tube to each end of the metal rod.

[0024] S23. After covering all surfaces of the conduit mold with the release agent, let it stand for 30 minutes.

[0025] S24. Place one porous glass tube at one end of the guide tube mold, press the other half of the guide tube mold tightly, and leave the other porous glass tube suspended to leave an injection hole.

[0026] S25. Select a first hyperelastic material with stiffness similar to that of the interventional soft catheter as the catheter tip material, and mix them in a certain proportion and stir them thoroughly to make them evenly mixed.

[0027] S26. Place the uniformly mixed first superelastic material into a vacuum pump to remove air bubbles, and carefully inject it into the conduit mold with a syringe. Then, embed the suspended porous glass tube into the conduit mold.

[0028] S27. After heat treatment of the catheter mold to solidify the superelastic material, remove it and carefully demold it to obtain an interventional soft catheter with a single stiffness catheter tip.

[0029] Furthermore, the catheter tip processing in step S3 includes the following sub-steps:

[0030] S31. Trim the single-stiffness catheter tip obtained from demolding to the required length and keep the cross-section flat to obtain the processed interventional soft catheter.

[0031] Furthermore, the process of multi-stiffness treatment at the catheter tip in step S4 includes the following sub-steps:

[0032] S41. Re-fix the processed interventional soft catheter into the half-catheter mold, and insert the metal rod into the corresponding through hole of the porous glass tube to constrain its position.

[0033] S42. Cover all surfaces of the conduit mold with the release agent and press it with the other half of the conduit mold, then let it stand for 30 minutes.

[0034] S43. Inject the Nth hyperelastic material with a stiffness relative to the previous hyperelastic material into the mold, so that the stiffness of the guide head gradually changes along the axis, and then merge the two molds to fix them.

[0035] S44. After heat-treating the mold to solidify the material, remove it and carefully demold it.

[0036] Further, after step S44, the following steps are performed:

[0037] S45. Repeat the catheter tip processing process, and trim the catheter after demolding N-1 times (in this invention, the purpose of repeating N-1 times after S3 is to prepare N segments, that is, catheter tips with stiffness gradients) to the required length, and keep the cross-section flat.

[0038] Furthermore, by varying the stiffness of the hyperelastic material and repeating the multi-stiffness treatment process at the tip of the conduit, a soft structure with a stiffness gradient is obtained, the stiffness gradient being determined by the properties of the selected hyperelastic material.

[0039] A second objective of this invention is to provide an interventional soft catheter with a stiffness gradient, the interventional soft catheter with a stiffness gradient comprising a catheter tip, a catheter body, and a drive wire; the catheter tip is interference-fitted with the catheter body; the drive wire extends into through holes arranged in a circumferential array at the catheter tip.

[0040] Furthermore, the catheter tip uses a hyperelastic material with a stiffness gradient, the stiffness of which varies gradient along the axis.

[0041] Furthermore, the specific preparation of the superelastic material (including the first superelastic material and the Nth superelastic material) is as follows: silicone is selected as the material of the catheter tip. The A glue, B glue and silicone thinner of the silicone material are mixed in a mass ratio or volume ratio of 1:1:x and stirred thoroughly to make them evenly mixed (the mixing ratio of silicone thinner is determined according to the actual stiffness of the catheter body. The higher the proportion of silicone thinner, the lower the material stiffness).

[0042] Optionally, the stiffness of each catheter tip can be approximately i / (N+1) of the catheter body, where i is the position of the catheter tip.

[0043] Furthermore, the main body of the catheter uses a medically common, biocompatible catheter.

[0044] Furthermore, the drive wire uses a super-elastic metal wire, such as a nickel-titanium super-elastic metal wire.

[0045] Furthermore, the material of the conduit mold is polyurethane resin.

[0046] Optionally, the stiffness of the adjacent catheter tip segments differs by 1 / (N+1) (where N is the number of catheter tip segments).

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] 1. The present invention provides an interventional soft catheter and method with a stiffness gradient. The tip of the interventional soft catheter with a stiffness gradient has a soft structure made of a highly elastic soft material, which provides higher safety when interacting with the fragile internal structures of the human body. Furthermore, the catheter tip can be actively bent via a wire-driven method, giving the catheter greater degrees of freedom to address the issue of reduced mobility when the catheter penetrates the human body. The stiffness of one side of the catheter tip is similar to that of the catheter body, and its stiffness varies gradually along the axis. This gradient stiffness ensures a uniform change in curvature when the catheter tip bends, preventing abrupt changes that could scratch or damage the inner wall of the blood vessel.

[0049] 2. The present invention provides an interventional soft catheter and method with a stiffness gradient. This interventional soft catheter with a stiffness gradient is a soft medical robot integrating a flexible tip that can bend independently. The bending direction and angle of the catheter tip can be controlled by tightening or loosening the drive wire inside the tip, thus greatly reducing the complexity of minimally invasive surgery and enabling the treatment of more complex lesions. During treatment, the physician can control the catheter's movement via a host computer, ensuring the physician's safety and significantly improving the efficiency of minimally invasive surgery. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the catheter mold used in step S1 of the present invention for preparing an interventional soft catheter with a stiffness gradient.

[0051] Figure 2 This is a schematic diagram of step S2 of the preparation of a single-stiffness catheter tip for an interventional soft catheter with a stiffness gradient provided by the present invention.

[0052] Figure 3 This is a schematic diagram of the catheter tip treatment in step S3 of an interventional soft catheter with a stiffness gradient provided by the present invention.

[0053] Figure 4 This is a schematic diagram of step S4 of the present invention, which involves the preparation of a multi-stiffness catheter tip.

[0054] Figure 5 This is a schematic diagram of the structure of an interventional soft catheter with a stiffness gradient provided by the present invention.

[0055] Figure 6 This is a three-dimensional structural diagram of an interventional soft catheter with a stiffness gradient provided by the present invention.

[0056] In the diagram: 1. Catheter tip, 2. Catheter body, 3. Drive line. Detailed Implementation

[0057] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0058] Any preparation methods, materials, structures, or composition ratios not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0059] The interventional soft catheter with stiffness gradient includes a soft catheter tip, a catheter body, and a drive line; the catheter structure adopts a soft structure with stiffness gradient; the catheter manufacturing process adopts a two-stage manufacturing method, which is divided into a mold manufacturing process and a catheter tip manufacturing process; the catheter tip manufacturing process is divided into a single stiffness manufacturing process, a catheter tip processing process, and a multi-stiffness manufacturing process.

[0060] The mold manufacturing process includes the following steps:

[0061] S1: Based on the structural dimensions of the required interventional soft catheter, customize the corresponding glass slide and glass rod, wherein the thickness of the glass slide is the same as the radius of the catheter, and the diameter of the glass rod is the same as the diameter of the catheter.

[0062] S2: Attach the custom-made glass rod to the glass slide, and then attach the custom-made glass sheet to both sides of the glass rod.

[0063] S3: Cut four glass pieces according to the glued dimensions so that they can just surround the glass piece and glass rod in S2 and form a closed cavity.

[0064] S4: After covering all surfaces of the mold with the release agent, let it stand for 30 minutes.

[0065] S5: Mix the mold materials in a certain proportion and stir thoroughly to make them evenly mixed.

[0066] S6: Place the well-mixed material into a vacuum pump to remove air bubbles, and carefully inject it into the mold to prevent air bubbles from forming. Then use a blade to scrape off the material that overflows from the mold.

[0067] S7: After heat-treating the mold to solidify the material, remove it and carefully demold it.

[0068] The aforementioned single-stiffness fabrication process for the catheter tip includes the following steps:

[0069] S1: Based on the structural dimensions of the required interventional soft catheter, a corresponding porous glass tube is customized, with the same diameter as the catheter.

[0070] S2: Fix the metal rod in the corresponding through hole in the porous glass tube.

[0071] S3: After covering all surfaces of the mold with the release agent, let it stand for 30 minutes;

[0072] S4: Place the porous glass tube at one end of the mold, press the other half of the mold together, and leave the other porous glass tube suspended with an injection hole.

[0073] S5: Select a superelastic material with similar stiffness to the catheter tip as the catheter tip material, and mix it in a certain proportion and stir it thoroughly to make it uniform.

[0074] S6: Place the well-mixed material into a vacuum pump to remove air bubbles, and carefully inject it into the mold with a syringe. Then, embed the suspended porous glass tube into the mold.

[0075] S7: After heat-treating the mold to solidify the material, remove it and carefully demold it.

[0076] The catheter tip processing procedure includes the following steps:

[0077] S1: Trim the long tube obtained from demolding to the required length and keep the cross-section flat.

[0078] The aforementioned multi-stiffness fabrication process for the catheter tip includes the following steps:

[0079] S1: Re-fix the processed guide tip into the mold and insert the metal rod into the corresponding through hole to constrain its position.

[0080] S2: After covering all surfaces of the mold with the release agent, let it stand for 30 minutes.

[0081] S3: Inject a superelastic material with varying stiffness into the mold, so that the stiffness of the guide tube tip gradually changes along the axis, and then merge the two molds to fix them.

[0082] S4: After heat-treating the mold to solidify the material, remove it and carefully demold it.

[0083] S5: Repeat the catheter tip treatment process, trim the long catheter after it has been cured again to the required length, and keep the cross-section flat.

[0084] S6: Repeat steps S1 to S5 to obtain a soft structure with a stiffness gradient, the stiffness gradient being determined by the properties of the selected hyperelastic material.

[0085] The catheter includes a soft catheter tip, a catheter body, and a drive wire. The soft catheter tip uses a hyperelastic material with a gradient stiffness along the axis, and the stiffness of one end is close to that of the catheter body. The catheter body uses a medically common, biocompatible catheter. The drive wire uses a hyperelastic metal wire.

[0086] The tip of the soft catheter is connected to the body of the catheter by an interference fit.

[0087] The drive wire extends into the through holes arranged in a circumferential array at the tip of the soft catheter and is fixed at one end.

[0088] The catheter tip with a stiffness gradient can match the stiffness of the catheter body, and the curvature can change uniformly when bending at a large angle.

[0089] In the following embodiments, the catheter tip uses a hyperelastic material with a stiffness gradient, the stiffness of which varies gradient along the axis.

[0090] In the following embodiments, the superelastic material is Dragon. 10SLOW high-performance silicone mixed with silicone thinner diluent. The specific preparation of the superelastic material is as follows: silicone is selected as the material of the catheter tip. The A and B components of the silicone material and the silicone thinner diluent are mixed in a mass ratio or volume ratio of 1:1:x, and stirred thoroughly to make them evenly mixed (the mixing ratio of silicone thinner diluent is determined according to the actual stiffness of the catheter body; the higher the proportion of silicone thinner diluent, the lower the material stiffness).

[0091] In the following embodiments, the catheter body uses a medically common, biocompatible catheter, specifically a commercially available Pebax catheter.

[0092] In the following embodiments, the drive wire uses a superelastic metal wire, specifically a nickel-titanium superelastic metal wire.

[0093] In the following embodiments, the catheter mold material is polyurethane resin, specifically... 327.

[0094] Example

[0095] like Figure 5 , 6As shown, this embodiment provides an interventional soft catheter with a stiffness gradient. The interventional soft catheter with a stiffness gradient includes a catheter tip 1, a catheter body 2, and a drive wire 3. The catheter tip 1 is interference-fitted with the catheter body 2. The drive wire 3 extends into through holes arranged in a circumferential array in the catheter tip 1. The catheter tip 1 is made of a hyperelastic material with a stiffness gradient, the stiffness of which varies gradient along the axis.

[0096] like Figures 1-4 The method for preparing the aforementioned interventional soft catheter with stiffness gradient includes the following steps:

[0097] S1. Prepare a catheter mold according to the structural dimensions of the required interventional soft catheter:

[0098] S11. Based on the structural dimensions of the required interventional soft catheter, prepare the corresponding first glass plate and glass rod, wherein the thickness of the first glass plate is the same as the radius of the interventional soft catheter, and the diameter of the glass rod is the same as the diameter of the interventional soft catheter.

[0099] S12. Attach the glass rod described in step S11 to the glass slide, and then attach the first glass slide described in step S11 to both sides of the glass rod.

[0100] S13. Cut four second glass sheets according to the glued dimensions, so that the four second glass sheets can just surround the first glass sheet and glass rod in S12 and form a closed cavity to obtain the master mold.

[0101] S14. After covering all surfaces of the master mold with the release agent, let it stand for 30 minutes.

[0102] S15. Mix the conduit mold material in a certain proportion and stir thoroughly to make it evenly mixed;

[0103] S16. Place the well-mixed conduit mold material into a vacuum pump to remove air bubbles, and carefully inject it into the master mold to prevent air bubbles from forming. Then use a blade to scrape off the material that overflows from the master mold.

[0104] S17. After heat treatment of the master mold to solidify the conduit mold material, remove it and carefully demold it to obtain the conduit mold.

[0105] S2. Using the catheter mold prepared in S1, prepare an interventional soft catheter with a single stiffness catheter tip:

[0106] S21. Based on the structural dimensions of the required interventional soft catheter, prepare a corresponding porous glass tube, wherein the diameter of the porous glass tube is the same as the diameter of the interventional soft catheter.

[0107] S22. Fix the metal rod in the corresponding through hole in the porous glass tube in step S21, and fix a porous glass tube to each end of the metal rod.

[0108] S23. After covering all surfaces of the conduit mold with the release agent, let it stand for 30 minutes.

[0109] S24. Place one porous glass tube at one end of the guide tube mold, press the other half of the guide tube mold tightly, and leave the other porous glass tube suspended to leave an injection hole.

[0110] S25. Select a first hyperelastic material with stiffness similar to that of the interventional soft catheter as the catheter tip material, and mix them in a certain proportion and stir them thoroughly to make them evenly mixed.

[0111] S26. Place the uniformly mixed first superelastic material into a vacuum pump to remove air bubbles, and carefully inject it into the conduit mold with a syringe. Then, embed the suspended porous glass tube into the conduit mold.

[0112] S27. After heat treatment of the catheter mold to solidify the superelastic material, remove it and carefully demold it to obtain an interventional soft catheter with a single stiffness catheter tip.

[0113] S3. The single-stiffness catheter tip of the interventional soft catheter prepared in S2 is processed to obtain the processed interventional soft catheter:

[0114] S31. Trim the single-stiffness catheter tip obtained from demolding to the required length and keep the cross-section flat to obtain the processed interventional soft catheter.

[0115] S4. Using the catheter mold prepared in S1, perform multi-stiffness processing on the catheter tip of the treated interventional soft catheter obtained in S3 (the catheter tip 1 in this embodiment includes N segments) to obtain a soft structure with stiffness gradient:

[0116] S41. Re-fix the processed interventional soft catheter into the half-catheter mold, and insert the metal rod into the corresponding through hole of the porous glass tube to constrain its position.

[0117] S42. Cover all surfaces of the conduit mold with the release agent and press it with the other half of the conduit mold, then let it stand for 30 minutes.

[0118] S43. Inject a hyperelastic material with a different stiffness (reduced stiffness) relative to the previous hyperelastic material into the mold, so that the stiffness of the guide head gradually changes along the axis, and then merge the two molds to fix them.

[0119] S44. After heat-treating the mold to solidify the material, remove it and carefully demold it.

[0120] S45. Repeat the catheter tip processing process, trim the catheter after multiple demoldings to the required length, and keep the cross-section flat.

[0121] Compared to the treated interventional soft catheter obtained in S3, the stiffness of the hyperelastic material is varied and the multi-stiffness treatment process (S41~S45) at the catheter tip is repeated N-1 times to obtain a soft structure with stiffness gradient.

[0122] S5. Connect the soft structure with stiffness gradient obtained in step S4 to the catheter body 2 and extend it into the drive line 3 to obtain the interventional soft catheter with stiffness gradient.

[0123] The stiffness (Shore hardness) of the catheter body 2 is 40D. In this embodiment, the stiffness of one end of the catheter tip 1 is close to the stiffness of the catheter body 2, which is i / (N+1) of the stiffness of the catheter body 2; the catheter tip 1 includes multiple connected segments; the stiffness gradient means the following: the stiffness of adjacent catheter tip 1 segments differs by 1 / (N+1). Where i is the position of the catheter tip segment, the position is counted from the end furthest from the catheter body 2, and N is the number of catheter tip 1 segments.

[0124] By simply changing the stiffness of the hyperelastic material in step S4 and repeating the multi-stiffness treatment process at the catheter tip a certain number of times, it is possible to prepare interventional soft catheters with different stiffness gradients.

[0125] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing an interventional soft catheter with a stiffness gradient, characterized in that, The preparation method includes the following steps: S1. Prepare a catheter mold according to the structural dimensions of the required interventional soft catheter; S2. Using the catheter mold prepared in S1, prepare an interventional soft catheter with a single stiffness catheter tip; S3. The single-stiffness catheter tip of the interventional soft catheter prepared in S2 is processed to obtain the processed interventional soft catheter. S4. Using the catheter mold prepared in S1, the treated interventional soft catheter obtained in S3 is subjected to multi-stiffness treatment at the catheter tip to obtain a soft structure with stiffness gradient, namely the catheter tip (1). S5. Connect the soft structure with stiffness gradient obtained in step S4 to the catheter body, that is, connect the catheter tip to the catheter body and extend it into the drive line to obtain the interventional soft catheter with stiffness gradient. The preparation of the single-stiffness catheter tip in step S2 includes the following sub-steps: S21. Based on the required structural dimensions of the interventional soft catheter, prepare a corresponding porous glass tube, wherein the diameter of the porous glass tube is the same as the diameter of the interventional soft catheter. S22. Fix the metal rod in the through hole of the porous glass tube in step S21, with a porous glass tube fixed at each end of the metal rod. S23. After covering all surfaces of the conduit mold with the release agent, let it stand. S24. Place one porous glass tube at one end of one half of the conduit mold, press the other half of the conduit mold together, and leave the other porous glass tube suspended with an injection hole. S25. Select the first superelastic material as the catheter tip material, and mix it in proportion and stir it thoroughly to make it uniform; S26. The first superelastic material after being mixed evenly is placed into a vacuum pump to remove air bubbles and injected into a conduit mold. Then, the suspended porous glass tube is embedded into the conduit mold. S27. After heat treatment of the catheter mold to solidify the superelastic material, remove it and demold it to obtain an interventional soft catheter with a single stiffness catheter tip. The catheter tip processing in step S3 includes the following sub-steps: S31. Trim the single-stiffness catheter tip obtained from demolding to the required length and keep the cross-section flat to obtain the processed interventional soft catheter. The process of multi-stiffness treatment at the catheter tip in step S4 includes the following sub-steps: S41. Re-fix the processed interventional soft catheter into the half-catheter mold and insert the metal rod into the through hole of the porous glass tube to constrain its position. S42. Cover all surfaces of the conduit mold with the release agent and press it with the other half of the conduit mold, then let it stand. S43. Inject the Nth hyperelastic material with a stiffness relative to the previous hyperelastic material into the mold, so that the stiffness of the guide head gradually changes along the axis, and then merge the two molds to fix them. S44. After heat-treating the mold to solidify the material, remove it and demold it.

2. The method for preparing an interventional soft catheter with a stiffness gradient according to claim 1, characterized in that, The preparation of the catheter mold in step S1 includes the following sub-steps: S11. Based on the structural dimensions of the required interventional soft catheter, prepare the corresponding first glass plate and glass rod, wherein the thickness of the first glass plate is the same as the radius of the interventional soft catheter, and the diameter of the glass rod is the same as the diameter of the interventional soft catheter. S12. Attach the glass rod described in step S11 to the glass slide, and then attach the first glass slide described in step S11 to both sides of the glass rod. S13. Cut four second glass sheets according to the glued dimensions, so that the four second glass sheets can just surround the first glass sheet and glass rod in S12 and form a closed cavity to obtain the master mold. S14. After covering all surfaces of the master mold with the release agent, let it stand. S15. Mix the conduit mold material according to the proportion and stir thoroughly to make it evenly mixed; S16. Place the well-mixed conduit mold material into a vacuum pump to remove air bubbles, and then inject it into the master mold. Scrape off the material that overflows from the master mold. S17. After heat treatment of the master mold to solidify the conduit mold material, remove it and demold it to obtain the conduit mold.

3. The method for preparing an interventional soft catheter with a stiffness gradient according to claim 1, characterized in that, The catheter mold includes two correspondingly arranged catheter mold halves.

4. The method for preparing an interventional soft catheter with a stiffness gradient according to claim 1, characterized in that, After step S44, perform the following steps: S45. Repeat the catheter tip processing process, trim the catheter after N demoldings to the required length, and keep the cross-section flat.

5. The method for preparing an interventional soft catheter with a stiffness gradient according to claim 1, characterized in that, By varying the stiffness of the hyperelastic material and repeating the multi-stiffness treatment process at the tip of the conduit, a soft structure with a stiffness gradient is obtained.

6. An interventional soft catheter with a stiffness gradient as described in any one of claims 1-5, characterized in that, The interventional soft device with stiffness gradient includes a catheter tip (1), a catheter body (2), and a drive line (3). The catheter tip (1) is press-fitted with the catheter body (2); The drive line (3) extends into the through hole at the tip of the conduit (1).

7. An interventional soft catheter with a stiffness gradient according to claim 6, characterized in that, The catheter tip (1) uses a hyperelastic material with a stiffness gradient, the stiffness of which varies along the axis. The drive wire uses a highly elastic metal wire; The catheter tip (1) comprises multiple connected segments; The stiffness of adjacent catheter tip (1) segments differs by 1 / (N+1), where N is the number of catheter tip (1) segments.

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