Self-expansion intravascular stent based on mixed negative Poisson's ratio structure

Abstract

The invention relates to the technical field of medical instruments, and discloses a self-expansion intravascular stent based on a mixed negative Poisson's ratio structure, which comprises an intravascular stent spliced by a plurality of concave honeycomb mechanisms and a plurality of chiral mechanisms, the inwards-concave honeycomb mechanism comprises a plurality of supports, and the supports are of inwards-concave honeycomb structures. The chiral mechanism comprises a plurality of chiral structures, each chiral structure comprises a ligament and two unclosed circular rings, and the two unclosed circular rings are fixedly connected to the two ends of the ligament respectively; cosine curved beams are arranged on the two sides of the support, connecting rods are fixedly connected to the cosine curved beams, connecting blocks are fixedly connected to the two ends of each chiral structure in the horizontal direction and the two ends of each chiral structure in the vertical direction, and one end of each connecting rod is fixedly connected with one connecting block on the adjacent chiral structure. The indent honeycomb structure and the chiral structure of the cosine curved beam structure are combined, stable supporting force can be provided, blood vessel collapse is effectively prevented, blood vessel smoothness is kept, the shape can be adjusted in a self-adaptive mode according to changes of the internal environment of the blood vessel, and damage to the blood vessel wall is reduced.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a self-expanding vascular stent based on a hybrid negative Poisson's ratio structure. Background Technology

[0002] With the continuous and rapid development of society, residents' lifestyles have undergone significant changes. Unhealthy habits such as unbalanced diets, insufficient physical exercise, and smoking are becoming increasingly common. Coupled with the increasingly serious aging population, the incidence of cardiovascular and cerebrovascular diseases continues to rise. Cardiovascular and cerebrovascular diseases have become a major challenge in the field of public health, urgently requiring effective prevention and control measures.

[0003] Currently, the main treatments for vascular stenosis include drug therapy, bypass surgery, and interventional stenting. Among these treatments, interventional therapy dominates due to its significant clinical efficacy and wide range of applications, with stent implantation being the preferred option due to its excellent therapeutic effect and high safety. The function of the stent itself and the complexity of the vascular structure place several demands on the mechanical properties of the stent structure, the most important of which include radial support force, flexibility, axial support force, axial shortening rate, and biocompatibility. There are interrelationships among the various performance indicators of the stent, making it difficult to scientifically achieve synergistic optimization of multiple performance indicators through general design methods alone.

[0004] With the continuous innovation and improvement of medical device technology, self-expanding stents, due to their unique material properties and working principle, have opened up new avenues for the clinical treatment of cardiovascular and cerebrovascular diseases. Based on the properties of superelastic materials, these vascular stents can expand autonomously without external pressure, offering a wider range of indications compared to traditional balloon-expandable stents. Simultaneously, self-expanding stents effectively maintain the physiological pulsation function of blood vessels, reduce damage to the vascular wall, and lower the risk of restenosis.

[0005] Negative Poisson's ratio structures have attracted widespread attention due to their superior mechanical properties. When subjected to lateral tension (or compression), a negative Poisson's ratio structure exhibits tension (or compression) in the longitudinal direction. Applying negative Poisson's ratio structures to vascular stents allows for increased stent strength while maintaining low surface coverage. Based on this characteristic, negative Poisson's ratio stents can adaptively adjust their shape according to changes in the intravascular environment, effectively mitigating stress concentration caused by physiological activities such as vascular bending, dilation, or contraction, achieving excellent apposition to the vessel wall.

[0006] In existing technologies, there is a significant gap between the inherent mechanical properties of negative Poisson's ratio structures and the mechanical properties required for vascular stents. Although negative Poisson's ratio structures provide favorable conditions for stents in terms of deformation behavior, their applicability in the specific engineering application of vascular stents still needs further improvement. Currently, the radial support and bending compliance of negative Poisson's ratio stents still require further optimization.

[0007] Therefore, there is an urgent need for a self-expanding vascular stent based on a hybrid negative Poisson's ratio structure to solve the above problems. Summary of the Invention

[0008] The purpose of this invention is to provide a self-expanding vascular stent based on a hybrid negative Poisson's ratio structure to solve the problems existing in the prior art.

[0009] To achieve the above objectives, the present invention provides the following solution: The present invention provides a self-expanding vascular stent based on a hybrid negative Poisson's ratio structure, comprising:

[0010] Multiple concave honeycomb structures and multiple chiral structures are staggered along the axial direction and spliced ​​together to form a vascular stent;

[0011] The concave honeycomb structure includes several supports, which are fixedly connected circumferentially to form a ring structure, and the supports are concave honeycomb structures.

[0012] The chiral mechanism includes several chiral structures, which are fixedly connected in the circumferential direction to form a ring structure. Each chiral structure includes a ligament and two open rings, which are respectively fixedly connected to both ends of the ligament.

[0013] The support has cosine curved beams on both sides, and connecting rods are fixedly connected to the cosine curved beams. Connecting blocks are fixedly connected to both ends of the chiral structure in the horizontal direction and both ends in the vertical direction. One end of the connecting rod is fixedly connected to one of the connecting blocks on the adjacent chiral structure.

[0014] According to the self-expanding vascular stent based on a hybrid negative Poisson's ratio structure provided by the present invention, one end of the connecting rod is fixedly connected to the concave point of the concave honeycomb structure.

[0015] According to the self-expanding vascular stent based on a hybrid negative Poisson's ratio structure provided by the present invention, the length of the horizontal rod in the stent is l, the length of the connecting rod is m, the mid-span height of the cosine curved beam is n, the distance between the horizontal rod and the connecting rod in the stent is h, where h is 0.628mm-1.256mm, and the angle between the cosine curved beam and the vertical direction is θ, where θ is less than 90°, and satisfies:

[0016] m>htanθ;

[0017] m>n;

[0018] l>2htanθ.

[0019] According to the self-expanding vascular stent based on a hybrid negative Poisson's ratio structure provided by the present invention, the stent and the connecting rod have a rod diameter of t1, where t1 is 70μm-120μm.

[0020] According to the self-expanding vascular stent based on a hybrid negative Poisson's ratio structure provided by the present invention, the two unclosed rings are located on the same circular outer diameter line.

[0021] According to the self-expanding vascular stent based on a hybrid negative Poisson's ratio structure provided by the present invention, the two adjacent chiral structures are mirror-distributed in the circumferential direction and are fixedly connected by the two adjacent connecting blocks.

[0022] According to the self-expanding vascular stent based on a hybrid negative Poisson's ratio structure provided by the present invention, the radius of the unclosed ring is R, where R is 0.528mm-1.206mm, the length of the ligament is L, where L is twice R, the angle between the ligament and the horizontal direction is α, where α is less than 90°, and the length of the connecting block is k, where k is 50μm-100μm.

[0023] According to the self-expanding vascular stent based on a hybrid negative Poisson's ratio structure provided by the present invention, the width of the unclosed annulus and the ligament is t2, and t2 is 70μm-120μm.

[0024] According to the self-expanding vascular stent based on a hybrid negative Poisson's ratio structure provided by the present invention, in the axial direction of the vascular stent, the number of both the concave honeycomb structure and the chiral structure is greater than one, and in the circumferential direction of the vascular stent, the number of both the concave honeycomb structure and the chiral structure is not less than two.

[0025] The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure provided by the present invention comprises a concave honeycomb structure and a chiral structure made of nickel-titanium alloy, copper-zinc-aluminum alloy, iron-manganese-silicon alloy, cobalt-based alloy, polyurethane, or polyimide material.

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] 1. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure provided by this invention, compared with the traditional concave honeycomb design, uses a cosine curve-shaped beam to construct its inclined part, which provides a stable mechanical property in the blood vessel, adapts to its expansion and contraction, allows the vascular stent to fit tightly against the blood vessel wall, and better adapts to the shape changes of the blood vessel. The cosine curve beam structure exhibits superior buffering capacity when subjected to pressure, effectively dispersing the stress concentration that may be generated in the stent structure, thereby reducing the risk of vascular stent failure.

[0028] 2. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure provided by this invention inherits the advantages of chiral structures and expands its application range and performance through innovative combinations and transformations, better adapting to changes in the shape of blood vessels and providing better compliance.

[0029] 3. This invention provides a self-expanding vascular stent based on a hybrid negative Poisson's ratio structure. By combining a concave honeycomb structure with a chiral structure, it maintains high strength and stiffness while enhancing the flexibility of the structure, giving it significant self-expanding performance and a negative Poisson's ratio effect. This not only provides stable radial support, effectively preventing vascular collapse and maintaining vascular patency, but also allows for shape adjustment according to physiological changes in the vascular environment. This effectively alleviates stress concentration during physiological bending, expansion, or contraction of the blood vessel, reducing the risk of intimal damage. It also enhances the stent's apposition performance, enabling it to better adapt to the complex vascular environment and optimizing its overall biomechanical performance. Furthermore, it proposes innovative solutions to address multiple performance limitations of existing technologies. By precisely controlling geometric parameters, it achieves synergistic optimization of key performance indicators such as radial support force, flexibility, axial support force, axial shortening rate, and biocompatibility. Especially in interventional vascular treatment, it provides a more scientific and efficient medical approach. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the concave honeycomb structure of the present invention;

[0032] Figure 2 This is a schematic diagram of a vascular stent structure composed of a concave honeycomb structure according to the present invention.

[0033] Figure 3 This is a schematic diagram of the chiral structure of the present invention;

[0034] Figure 4 This is a schematic diagram of a vascular stent structure composed of chiral structures according to the present invention;

[0035] Figure 5 This is a schematic diagram showing the connection state between the concave honeycomb structure and the chiral structure of the present invention;

[0036] Figure 6This is a schematic diagram of the vascular stent structure composed of a concave honeycomb structure and a chiral structure according to the present invention.

[0037] Figure 7 This is a schematic diagram of radial compression of the vascular stent of the present invention;

[0038] Figure 8 This is a schematic diagram of the vascular stent simulating the cantilever beam bending method of the present invention;

[0039] Figure 9 This is a schematic diagram of the longitudinal compression of the vascular stent of the present invention;

[0040] Figure 10 This is a schematic diagram of the vascular stent clamping process of the present invention;

[0041] Figure 11 This is a stress distribution cloud diagram illustrating the radial support performance of the vascular stent of the present invention.

[0042] Figure 12 This is a stress distribution cloud diagram illustrating the compliance performance of the vascular stent of the present invention.

[0043] Figure 13 This is a stress distribution cloud diagram illustrating the longitudinal support performance of the vascular stent of the present invention.

[0044] Figure 14 This is a data curve of the vascular stent of the present invention;

[0045] Figure 15 This is a schematic diagram of data for different types of supports in this invention;

[0046] Among them, 1. bracket; 2. connecting rod; 3. ligament; 4. unclosed ring; 5. connecting block. Detailed Implementation

[0047] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] Reference Figures 1-15 The present invention provides a self-expanding vascular stent based on a hybrid negative Poisson's ratio structure, comprising:

[0050] Multiple concave honeycomb structures and multiple chiral structures are staggered along the axial direction and spliced ​​together to form a vascular stent;

[0051] The concave honeycomb structure includes several supports 1, which are fixedly connected in the circumferential direction to form a ring structure. The supports 1 are concave honeycomb structures.

[0052] The chiral mechanism includes several chiral structures, which are fixedly connected in the circumferential direction to form a ring structure. The chiral structure includes a ligament 3 and two unclosed rings 4, which are fixedly connected to both ends of the ligament 3 respectively.

[0053] The bracket 1 has cosine curved beams on both sides, and connecting rods 2 are fixedly connected to the cosine curved beams. Connecting blocks 5 are fixedly connected to both ends of the chiral structure in the horizontal direction and both ends in the vertical direction. One end of the connecting rod 2 is fixedly connected to one of the connecting blocks 5 on the adjacent chiral structure.

[0054] In one embodiment of the present invention, reference is made to Figures 1-6 Compared to traditional concave honeycomb designs, the concave honeycomb structure in this application employs cosine-curved beams to construct its sloping sections. This improved structure consists of a standard concave honeycomb frame and innovative cosine curved beams. Along the central axis, the vertices of the honeycomb unit frame are connected to the vertices of adjacent curved beam units via connecting elements, thereby providing stable mechanical properties within the blood vessel to accommodate its expansion and contraction. In the circumferential layout, the edges of each honeycomb unit are tightly joined to the edges of adjacent units, forming a continuous ring structure. This continuous design allows the vascular stent to fit closely to the vessel wall, better adapting to changes in vessel shape. Furthermore, the cosine curved beam structure exhibits superior buffering capacity under pressure, effectively dispersing stress concentrations that may occur within the stent structure, thereby reducing the risk of vascular stent failure.

[0055] This application's chiral structure is derived from traditional chiral structures through transformation and combination. Traditional chiral structures consist of a circular ring and four equidistant ligaments. These ligaments are tangent to the ring, forming specific corner points. New units are constructed through the parallel arrangement of multiple chiral structures and the connection of adjacent ligaments. This structure utilizes a chiral deformation model based on the ring and ligaments to achieve negative Poisson's ratio characteristics through a specific rotation mechanism. This design not only inherits the advantages of chiral structures but also expands their application range and performance through innovative combinations and transformations. This application's chiral structure inherits the negative Poisson's ratio characteristics of traditional chiral structures, enabling the stent to contract simultaneously in both the axial and radial directions, while also exhibiting good flexibility and reducing damage to vascular tissues.

[0056] As an optional implementation, one end of the connecting rod 2 is fixedly connected to the concave point of the concave honeycomb structure.

[0057] As an optional implementation, the length of the horizontal rod in support 1 is l, the length of the connecting rod 2 is m, the mid-span height of the cosine curved beam is n, the distance between the horizontal rod and the connecting rod 2 in support 1 is h, where h is 0.628mm-1.256mm, and the angle between the cosine curved beam and the vertical direction is θ, where θ is less than 90°, and satisfies:

[0058] m>htanθ;

[0059] m>n;

[0060] l>2htanθ.

[0061] In one embodiment of the present invention, the shape function of the cosine curved beam is given by the formula y(x)=h[1-cos(2πx / n)], where n is the mid-span height of the cosine curved beam and h is half the span length of the cosine curved beam. In this structure, the design of the cosine curved beam preserves the axial symmetry of each concave honeycomb unit. In the horizontal direction, the vertex of the border of each concave honeycomb unit is connected to the vertex of the adjacent cosine curved beam structural unit, and the intersection of the cosine curved beam and the connecting body is located at half the span length of the cosine curved beam. In the circumferential direction, the edge of the border of each concave honeycomb unit coincides with the edge of the adjacent unit, forming a continuous ring structure. This special construction provides stable mechanical properties in the vascular environment by utilizing the expansion and contraction of the honeycomb units. In the circumferential direction, the edge of the border of each concave honeycomb unit coincides with the edge of the adjacent unit, forming a continuous ring structure. This design allows the vascular stent to better adapt to changes in the shape of the blood vessel, achieving good adhesion. Meanwhile, the design of the cosine curved beam also gives the structure good buffering performance during compression, avoiding stress concentration in the vascular stent structure.

[0062] As an optional implementation, the diameter of the bracket 1 and the connecting rod 2 is t1, where t1 is 70μm-120μm.

[0063] As an alternative implementation, the two unclosed rings 4 are located on the same outer diameter line.

[0064] As an optional implementation, adjacent chiral structures are mirror-distributed in the ring direction and are fixedly connected by adjacent connecting blocks 5.

[0065] In one embodiment of the present invention, reference is made to Figure 4 The two adjacent chiral structures in the axial and circumferential directions are mirror images.

[0066] As an optional implementation, the radius of the unclosed ring 4 is R, where R is 0.528mm-1.206mm, the length of the ligament 3 is L, where L is twice R, the angle between the ligament 3 and the horizontal direction is α, where α is less than 90°, and the length of the connecting block 5 is k, where k is 50μm-100μm.

[0067] As an optional implementation, the width of the unclosed ring 4 and ligament 3 is t2, which is 70μm-120μm.

[0068] As an alternative implementation, the number of concave honeycomb structures and chiral structures in the axial direction of the vascular stent is greater than one, and the number of concave honeycomb structures and chiral structures in the circumferential direction of the vascular stent is not less than two.

[0069] In one embodiment of the present invention, the number of negative Poisson's ratio structural units in the circumferential direction of the vascular stent is greater than or equal to 2, and the number can be reasonably selected according to the blood vessel diameter; in the axial direction of the vascular stent, the number of negative Poisson's ratio structural units is greater than 1, the thickness of the vascular stent is 0.025-0.177mm, and the number and length of the negative Poisson's ratio structural units arranged axially are determined according to the blood vessel length.

[0070] As an optional implementation, the concave honeycomb structure and the chiral structure are made of nickel-titanium alloy, copper-zinc-aluminum alloy, iron-manganese-silicon alloy, cobalt-based alloy, polyurethane or polyimide material.

[0071] In one embodiment of the present invention, the vascular stent with a hybrid negative Poisson's ratio structure is suitable for metallic superelastic materials, such as nickel-titanium alloys and copper-zinc-aluminum alloys, and can also be non-metallic superelastic materials such as polyurethane and polyimide. The vascular stent can be fabricated using selective laser melting (SLM), microscale selective laser melting (SLM), fused deposition modeling (FDM), laser cutting, or similar techniques.

[0072] In one embodiment of the present invention, reference is made to Figure 5 , Figure 6 A hybrid vascular stent structure, combining concave honeycomb and chiral structures, is employed. Each 3D model of the stent consists of six interconnected units in the circumferential direction and varying numbers of units in the axial direction. The stent thickness ranges from 0.025 to 0.177 mm, and its diameter and length can be adjusted according to specific requirements. The concave honeycomb structure primarily enhances the stent's stiffness, ensuring its radial and axial support performance. The chiral structure better adapts to changes in blood vessel shape, providing improved flexibility.

[0073] In one embodiment of the present invention, reference is made to Figure 7 , Figure 10 , Figure 14 , Figure 7The geometric parameters of the upper and lower pressure plates are 5mm×3mm×0.05mm. By applying a displacement load to the upper pressure plate to compress the stent diameter to half of the nominal diameter, the radial force of the vascular stent is calculated to characterize the radial support performance of the stent.

[0074] Figure 10 Throughout the entire compression process of the support structure, regardless of the type, the area of ​​maximum stress is located at the curved section of the support ring, while the stress on the connecting ribs is relatively low, indicating that this area has the lowest probability of fracture failure. Specifically, the maximum stress area for NS and NC type support structures is at the connection between the horizontal bar and the cosine curved beam in the concave honeycomb structure, while the maximum stress area for the S type support structure is on the inner surface of the diagonal bar and the curved section. Overall, the stress distribution of the support structure is mainly concentrated in the support ring, with lower stress in the connecting ribs. This indicates that during radial compression, the support ring primarily provides radial support, while the connecting ribs hardly deform, thus experiencing lower stress.

[0075] Figure 14 The radial displacement-force curves obtained after radial compression of different types of vascular stents show that the three types of stents maintain consistent trends in force and displacement. When the stent is radially compressed by 1.2 mm, it is compressed to half its initial diameter, at which point the stent's supporting force is at its maximum. The pressures required for 50% compression of these three types of stents are 1.76 N, 2.42 N, and 1.87 N, respectively. This result indicates that there is no significant difference in their radial support performance.

[0076] In one embodiment of the present invention, reference is made to Figure 8 , Figure 11 , Figure 14 , Figure 8 A vascular stent is fixed at one end and a force load is applied to the other end. The bending stiffness of the vascular stent is calculated to characterize the flexibility of the stent.

[0077] Figure 11 In the process of bending, the stress on the three types of supports is not large. In addition, from the perspective of the entire bending process of the supports, the area of ​​maximum stress on the supports, regardless of the type, is on the inner surface of the arc bending point of the pressure bending area.

[0078] Figure 14 The force and displacement curves of different vascular stent structures after bending are shown in the figure. It can be seen from the figure that the force and displacement have a linear relationship. The slopes of the NS type, NC type and S type stents are 5.27, 3.38 and 21.06, respectively, and the maximum bending displacements are 0.26mm, 0.17mm and 1.05mm, respectively. It can be seen that the S type stent is the stent structure that is most easily bent by the force. This is mainly because the bending degree of the whole structure is large and the width of the connection part is small.

[0079] In one embodiment of the present invention, reference is made to Figure 9 , Figure 12 , Figure 14 , Figure 9 The geometric parameters of the upper and lower cylinders are 2.4mm×1.5mm×0.1mm. By applying a displacement load to the upper cylinder to compress the stent length by 4% of the total length, the axial force of the vascular stent is calculated to characterize the axial support performance of the stent.

[0080] Figure 12 The stress distribution cloud map obtained from simulating the longitudinal support performance of vascular stents shows that the location of the maximum stress area differs for different stent types. For example, the maximum stress area of ​​NS and NS-type stents is on the inner surface of the curved section, while the maximum stress area of ​​S-type stents is mainly concentrated on the outer surface of the connection between the rectangular connector and the curved section. This may be due to the difference in flexibility between the semi-circular region and the connector of the S-type stent during axial compression.

[0081] Figure 14 The graph shows the longitudinal force versus compression displacement curves of different vascular stent structures after longitudinal compression. The pressures required for 4% compression of the NS, NC, and S-type stents are 4.66 N, 8.67 N, and 0.47 N, respectively. The graph shows that the NC stent has the best longitudinal support performance, while the S-type stent has the worst. This is because the NC stent evolved from a concave honeycomb structure and possesses the high rigidity characteristic of traditional honeycomb structures, while the S-type stent has good flexibility due to its chiral structure. During axial compression, the axial connector width is small, and all units are composed of arcs, resulting in significantly less axial resistance compared to the other two types of stents.

[0082] Figure 10 The diagram illustrates the compression process of a vascular stent with a hybrid negative Poisson's ratio structure. A thin-walled cylinder with a variable diameter is used to compress the stent. The cylinder has dimensions of 2.4 mm × 8 mm. The stent is radially compressed by applying a displacement load to the thin-walled cylinder, and the axial shortening rate of the vascular stent is calculated.

[0083] The preferred material for manufacturing the scaffold is a superelastic nickel-titanium alloy. Based on the macroscopic phenomenological model of shape memory alloys, the material constitutive model is defined using the following parameters: elastic modulus E = 44.27 GPa, Poisson's ratio v = 0.33, and density ρ = 6.5 g / cm³. 3 The critical stress value σ at which stress-induced martensitic transformation begins S AS =566 MPa, the critical stress value σ at which stress-induced martensitic transformation ends. FAS =638 MPa, the critical stress value σ at which stress-induced reverse martensitic transformation begins. S SA =128 MPa, the critical stress value σ at which stress-induced reverse martensitic transformation ends. F SA =84 MPa, recoverable strain or maximum residual strain e L =0.0596mm -1 The elastic modulus E of the fully martensitic phase S =37 GPa.

[0084] Reference Figure 15 The diagram shows the axial shrinkage rate of different types of stents during self-expansion. All the designed stents have a negative Poisson's ratio effect, so the axial shrinkage rate is negative. The diagram does not consider positive or negative signs, only numerical values. The axial shrinkage rates of NS type stent, NC type stent and S type stent are -6.97%, -7.74% and -13.5%, respectively. The effect of nickel-titanium alloy on the axial shrinkage rate of the three types of stents is consistent. As the stent self-expands, the axial distance increases.

[0085] Reference Figure 15 The stress on different types of stents is as follows: after implantation in a blood vessel, the stent bears the instantaneous pressure caused by blood pressure and vascular elasticity, as well as the long-term pressure during the healing process. Therefore, the stent should have sufficient radial force to support the blood vessel wall, thereby preventing stent slippage or collapse. However, excessive radial force can cause vascular damage. In this application, the stress on different types of stents is greater than 30 kPa, indicating that all three types of stents have sufficient radial force.

[0086] Reference Figure 15 The bending stiffness of different types of supports is shown in the figure. It can be seen that the bending stiffness of the S-type support is the lowest at 6.75 N·mm. 2 The NC type bracket has a maximum bending stiffness of 69.7 N·mm. 2 Except for the S-shaped bracket, which has lower bending stiffness, the others all range from 11.7 to 88.1 N·mm. 2 Within the range.

[0087] Therefore, the vascular stent with the hybrid negative Poisson's ratio structure in this application has excellent mechanical properties and biocompatibility. It can adaptively adjust its shape according to changes in the internal vascular environment, thereby reducing damage to the vascular wall and achieving good adhesion effect, and has broad prospects in the field of medical devices.

[0088] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0089] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A self-expanding vascular stent based on a hybrid negative Poisson's ratio structure, characterized in that, include: Multiple concave honeycomb structures and multiple chiral structures are staggered along the axial direction and spliced ​​together to form a vascular stent; The concave honeycomb structure includes several supports (1), and the several supports (1) are fixedly connected in the circumferential direction to form a ring structure. The supports (1) are concave honeycomb structures. The chiral mechanism includes several chiral structures, which are fixedly connected in the circumferential direction to form a ring structure. The chiral structure includes a ligament (3) and two unclosed rings (4), which are fixedly connected to both ends of the ligament (3). The bracket (1) has cosine curved beams on both sides, and a connecting rod (2) is fixedly connected to the cosine curved beams. Both ends of the chiral structure in the horizontal direction and both ends in the vertical direction are fixedly connected to connecting blocks (5). One end of the connecting rod (2) is fixedly connected to one of the connecting blocks (5) on the adjacent chiral structure.

2. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 1, characterized in that: One end of the connecting rod (2) is fixedly connected to the concave point of the concave honeycomb structure.

3. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 1, characterized in that: The length of the horizontal rod in the support (1) is l, the length of the connecting rod (2) is m, the mid-span height of the cosine curved beam is n, the distance between the horizontal rod and the connecting rod (2) in the support (1) is h, h is 0.628mm-1.256mm, the angle between the cosine curved beam and the vertical direction is θ, θ is less than 90°, and satisfies: m>htanθ; m>n; l>2htanθ.

4. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 1, characterized in that: The diameter of the bracket (1) and the connecting rod (2) is t1, which is 70μm-120μm.

5. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 1, characterized in that: The two unclosed rings (4) are located on the same outer diameter line.

6. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 1, characterized in that: The two adjacent chiral structures are mirror images of each other and are fixedly connected by the two adjacent connecting blocks (5).

7. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 1, characterized in that: The radius of the unclosed ring (4) is R, which is 0.528mm-1.206mm. The length of the ligament (3) is L, which is twice the length of R. The angle between the ligament (3) and the horizontal direction is α, which is less than 90°. The length of the connecting block (5) is k, which is 50μm-100μm.

8. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 1, characterized in that: The width of the unclosed ring (4) and the ligament (3) is t2, which is 70μm-120μm.

9. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 1, characterized in that: In the axial direction of the vascular stent, the number of both the concave honeycomb structure and the chiral structure is greater than one; in the circumferential direction of the vascular stent, the number of both the concave honeycomb structure and the chiral structure is not less than two.

10. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 1, characterized in that: The concave honeycomb structure and the chiral structure are made of nickel-titanium alloy, copper-zinc-aluminum alloy, iron-manganese-silicon alloy, cobalt-based alloy, polyurethane, or polyimide material.

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