A new self-expanding vascular stent based on mixed negative poisson's ratio structure

Abstract

The application discloses a novel self-expanding vascular stent based on a mixed negative Poisson's ratio structure. The mixed negative Poisson's ratio structure is formed by periodically expanding a single cell in a plane, and the cell is formed by mixing a traditional concave negative Poisson's ratio cell with an arrow structure and a snake structure. The mixed negative Poisson's ratio structure better retains the negative Poisson's ratio performance of the traditional concave honeycomb, and meanwhile, the bending stiffness in the vertical direction and the bending flexibility in the horizontal direction are enhanced. The proposed vascular stent is formed by curling the structure in space and is prepared from a shape memory metal. The proposed stent has the double performances of self-expansion and negative Poisson's ratio, and meanwhile, the radial support and the axial compliance of the traditional structure are further improved, and the stent has excellent mechanical properties and biocompatibility.

Description

Technical Field

[0001] This invention belongs to the field of vascular stents, specifically relating to a novel self-expanding vascular stent based on a hybrid negative Poisson's ratio structure. Background Technology

[0002] As a common cardiovascular interventional device, vascular stents have been used to treat various atherosclerosis-related diseases. The function of the stent itself and the complexity of the vascular structure place several requirements on the mechanical properties of the stent structure, the most important of which include radial support, axial flexibility, axial shortening rate, and biocompatibility.

[0003] Traditional balloon-expandable (BE) stents rely on balloon inflation to cause plastic deformation of the structure and use the balloon's expansion force to directly open the diseased blood vessel. This process may result in either incomplete or excessive stent deployment. The former can easily lead to neointimal hyperplasia between the stent and the vessel wall, increasing the risk of in-stent restenosis; the latter may cause vascular damage or rupture.

[0004] Furthermore, the elastic recoil of the stent when the supporting balloon is removed can also lead to late stent misalignment. Self-expanding (SE) stents are considered to offer significant advantages in addressing these issues. SE stents are typically confined within a delivery catheter and, upon deployment at the designated location, automatically expand to open the diseased vessel using their own elastic force. Due to the gradual release of elastic strain energy, SE stents can continuously support the vessel wall, reducing the risk of poor stent implantation and late-stage complications.

[0005] However, due to the lower Young's modulus of the hyperelastic material, the support strength of the SE stent is significantly lower than that of the BE stent. Furthermore, due to the shortening effect of the structure, incomplete coverage during stent opening can easily lead to restenosis.

[0006] Therefore, it is of great significance to develop a new generation of scaffolds with excellent mechanical properties and biocompatibility.

[0007] Negative Poisson's ratio structures are artificial structures with unique deformation capabilities, differing from conventional positive Poisson's ratio materials and structures. They exhibit anomalous lateral expansion behavior under tension. Vascular stents designed based on negative Poisson's ratio structures overcome the axial shortening effect of traditional stents and have attracted widespread attention.

[0008] Publication number CN113693798A, entitled "A Shape Memory Alloy Vascular Stent Based on Expansion Honeycomb and Its Fabrication Method," discloses a vascular stent composed of multiple periodic unit cells, with the basic unit cell being a concave honeycomb structure exhibiting an expansion effect. In this application, due to the concave honeycomb structure and its unique combination method, traditional concave honeycomb stents suffer from poor radial support and axial bending performance. Further improvements in the support and flexibility of the stent are needed for its application in implanted vascular stents. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of existing traditional concave honeycomb stents in terms of poor radial support and axial bending performance, and to provide a novel self-expanding vascular stent based on a hybrid negative Poisson's ratio structure.

[0010] The technical solution of the present invention: The present invention discloses a vibration perception threshold (VPT) detector that can automatically measure the vibration perception threshold, including a vascular stent with a ring-shaped tubular structure composed of a plurality of cell components with negative Poisson's ratio effect, wherein the cell components include cells that are symmetrical vertically and horizontally and flexible connection structures. The cell unit includes a first horizontal cell wall and a second horizontal cell wall arranged in parallel; the first horizontal cell wall and the second horizontal cell wall are symmetrical about the lateral cell walls. The first horizontal cell wall has a first oblique cell wall at each end; The second horizontal cell wall has a second oblique cell wall at each end; The first horizontal cell wall, the second horizontal cell wall, the first oblique cell wall, and the second oblique cell wall form a hexagonal cell unit structure. A lateral cell wall is provided at the intersection of the first oblique cell wall and the second oblique cell wall; the lateral cell wall is parallel to the first horizontal cell wall; the first horizontal cell wall and the second horizontal cell wall are symmetrical about the lateral cell wall; The lateral cell wall is symmetrically provided with a first cell wall and a second cell wall on both sides; the first cell wall is parallel to the first oblique cell wall; the second cell wall is parallel to the second oblique cell wall; In the annular horizontal direction, two adjacent cell components are connected in series through a flexible connection structure connected by the side cell walls; In the vertical direction of the ring, two adjacent cell components are stacked vertically, and the first horizontal cell walls overlap each other.

[0011] Furthermore, the flexible connection structure includes a first vertical cell wall, a second vertical cell wall, and a third vertical cell wall arranged in parallel and at equal intervals; the first vertical cell wall and the third vertical cell wall are symmetrical about the midpoint of the second vertical cell wall; the first vertical cell wall and the second vertical cell wall are respectively connected to the upper and lower ends of the second vertical cell wall through transition sections.

[0012] Furthermore, the angle between the first horizontal cell wall and the first oblique cell wall Less than 90 degrees.

[0013] Furthermore, the lateral cell wall is located outside the hexagonal cell structure.

[0014] Furthermore, the first oblique cell wall has the same length as the first cell wall.

[0015] Furthermore, the length of the first vertical cell wall is half the length of the second vertical cell wall.

[0016] Furthermore, the cell assembly is made of shape memory alloy.

[0017] Furthermore, the cell assembly is made of a nickel-titanium alloy.

[0018] The beneficial effects of this disclosure are as follows: 1. The cell components constituting the vascular stent in this invention are an improvement upon the traditional concave negative Poisson's ratio cell. By altering the structure of the cell components themselves and their arrangement, the bending stiffness in the vertical direction and the bending flexibility in the horizontal direction are significantly improved. This allows the vascular stent constructed from these cell components to have high flexibility in certain applications. The vascular stent structure is designed based on the proposed hybrid negative Poisson's ratio structure, exhibiting a significant negative Poisson's ratio effect. It does not experience shortening when deployed within the blood vessel, thus avoiding the adverse consequences of incomplete plaque coverage.

[0019] 2. Vascular stents possess the excellent properties of self-expanding stents, such as good expansion performance, biocompatibility, and continuous support performance; at the same time, due to structural improvements, compared with traditional concave honeycomb stents, this invention further enhances bending mechanical properties, making the stent more adaptable to the shape of curved blood vessels and providing stronger support. Attached Figure Description

[0020] Figure 1 is a schematic diagram of the specific structure of the cell component in this invention; Figure 2 is a schematic diagram of the combined state of several cell components in this invention; Figure 3 is Figure 2 A three-dimensional state diagram; Figure 4 This is a schematic diagram of the overall structure of the vascular stent in this invention; Figure 5 The computer simulation diagram of the vascular stent curling and unfolding process in this invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions 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, 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.

[0022] Based on the traditional concave cell, this invention designs a novel hybrid negative Poisson's ratio structure and proposes a novel negative Poisson's ratio self-deploying scaffold. The principle of this invention will be further explained below with reference to specific embodiments: Figure 1 A single-cell planar model of the proposed hybrid negative Poisson's ratio structure is presented. The cell components include cells that are symmetrical both vertically and horizontally, as well as flexible connection structures. The cell unit includes a first horizontal cell wall 11 and a second horizontal cell wall 12 arranged in parallel; the first horizontal cell wall 11 and the second horizontal cell wall 12 are symmetrical about the lateral cell wall 5; The first horizontal cell wall 11 has a first oblique cell wall 21 at each end; The second horizontal cell wall 21 has a second oblique cell wall 22 at each end; The first horizontal cell wall 11, the second horizontal cell wall 12, the first oblique cell wall 21, and the second oblique cell wall 22 form a hexagonal cell unit structure; the angle between the first horizontal cell wall 11 and the first oblique cell wall 21 Less than 90 degrees.

[0023] A lateral cell wall 5 is provided at the intersection of the first oblique cell wall 21 and the second oblique cell wall 22; the lateral cell wall 5 is located outside the hexagonal cell structure. The lateral cell wall 5 is parallel to the first horizontal cell wall 11; the first horizontal cell wall 11 and the second horizontal cell wall 12 are symmetrical about the lateral cell wall 5. The lateral cell wall 5 is symmetrically provided with a first cell wall 41 and a second cell wall 42 on both sides; the first cell wall 41 is parallel to the first oblique cell wall 21; the second cell wall 42 is parallel to the second oblique cell wall 22; the first oblique cell wall 21 and the first cell wall 41 have the same length.

[0024] In the annular horizontal direction, two adjacent cell components are connected in series through a flexible connection structure via the side cell wall 5; In the vertical direction of the ring, two adjacent cell components are stacked vertically, with the first horizontal cell walls 41 overlapping each other. The flexible connection structure includes a first vertical cell wall 61, a second vertical cell wall 62, and a third vertical cell wall 63 arranged in parallel and equidistantly; the first vertical cell wall 61 and the third vertical cell wall 63 are symmetrical about the midpoint of the second vertical cell wall 62; the first vertical cell wall 61 and the second vertical cell wall 62 are connected to the upper and lower ends of the second vertical cell wall 62 respectively through a transition section 64. The length of the first vertical cell wall 61 is half the length of the second vertical cell wall 62.

[0025] The cell components are made of nickel-titanium alloy.

[0026] Figure 2 A hybrid negative Poisson's ratio structure, formed by the periodic arrangement of the aforementioned cells, is presented. The number of cells in this structure is uniformly 3 in both the horizontal and vertical directions.

[0027] Cells combine with each other through replication and movement to ensure that each cell has the same structure and size. In the vertical direction, the upper and lower horizontal cell walls overlap each other, and the inclined cell walls connect with each other; In the horizontal direction, the left and right endpoints are connected to each other.

[0028] The overall dimensions of the structure can be adjusted by designing the length and height of the cells and the number of periodic arrangements to adapt to different application requirements.

[0029] In this invention, the cell wall of the hybrid structure is a beam structure with a rectangular cross-section, where the thickness and width of the rectangle are t and b, respectively. The thickness t is an in-plane parameter that can be used to adjust the porosity of the structure; the width b is an out-of-plane parameter that can be used to adjust the length of the structure stretched along the plane, wherein b / t should be between 1 and 2.

[0030] Figure 4 and 5 A three-dimensional structural diagram of the novel vascular stent is provided. This stent is formed by rolling up the aforementioned planar hybrid negative Poisson's ratio structure: Figure 2 and 3 The mixed negative Poisson's ratio structure is rolled up in the vertical direction, and the circumference of the cylinder formed by the roll-up is the vertical length of the original structure, and the height of the cylinder is the horizontal length of the original structure.

[0031] In this invention, the cell wall constituting the vascular stent is made of a nickel-titanium alloy cylindrical shell by laser cutting. The obtained blank also needs to be heat-treated, surface polished and chamfered. The final stent has good mechanical properties and biocompatibility, which can meet the needs of clinical use.

[0032] When a stent is deployed in a designated blood vessel, due to the negative Poisson's ratio effect, it expands radially and extends axially at the same time, thereby increasing the coverage area of ​​the stent and avoiding insufficient coverage.

[0033] Figure 5 Computer simulations of the stent's curling-unfolding process are presented, clearly showing that after unfolding, the stent expands to varying degrees in both the radial and axial directions. Specifically, the radial dimension recovers from 30% to 100% of its diameter; the axial dimension increases by 16% compared to when compressed, demonstrating the effectiveness of its negative Poisson's ratio performance.

[0034] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A self-expanding vascular stent based on a hybrid negative Poisson's ratio structure, comprising a vascular stent with a ring-shaped tubular structure composed of several cell components with negative Poisson's ratio effects, characterized in that: The cell component includes cells that are symmetrical both vertically and horizontally, and flexible connection structures. The cell unit includes a first horizontal cell wall (11) and a second horizontal cell wall (12) arranged in parallel; the first horizontal cell wall (11) and the second horizontal cell wall (12) are symmetrical about the lateral cell wall (5); The first horizontal cell wall (11) has a first oblique cell wall (21) at each end; The second horizontal cell wall (12) has a second oblique cell wall (22) at each end; The first horizontal cell wall (11), the second horizontal cell wall (12), the first oblique cell wall (21), and the second oblique cell wall (22) form a hexagonal cell unit structure; A lateral cell wall (5) is provided at the intersection of the first oblique cell wall (21) and the second oblique cell wall (22); the lateral cell wall (5) is parallel to the first horizontal cell wall (11); the first horizontal cell wall (11) and the second horizontal cell wall (12) are symmetrical about the lateral cell wall (5); The side cell wall (5) is symmetrically provided with a first cell wall (41) and a second cell wall (42) on both sides; the first cell wall (41) is parallel to the first oblique cell wall (21); the second cell wall (42) is parallel to the second oblique cell wall (22). In the annular horizontal direction, two adjacent cell components are connected in series through a flexible connection structure via the side cell wall (5); In the vertical direction of the ring, two adjacent cell components are stacked vertically, and the first horizontal cell wall (11) overlaps with each other; The lateral cell walls (5) are located on both sides of the hexagonal cell structure.

2. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 1, characterized in that: The flexible connection structure includes a first vertical cell wall (61), a second vertical cell wall (62), and a third vertical cell wall (63) arranged in parallel and at equal intervals; the first vertical cell wall (61) and the third vertical cell wall (63) are symmetrical about the midpoint of the second vertical cell wall (62); the first vertical cell wall (61) and the second vertical cell wall (62) are connected to the upper and lower ends of the second vertical cell wall (62) through a transition section (64).

3. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 2, characterized in that: The angle between the first horizontal cell wall (11) and the first oblique cell wall (21) is less than 90 degrees.

4. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 1, characterized in that: The first oblique cell wall (21) has the same length as the first cell wall (41).

5. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 2, characterized in that: The length of the first vertical cell wall (61) is half the length of the second vertical cell wall (62).

6. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to any one of claims 1-5, characterized in that: The cell assembly is made of shape memory alloy.

7. The self-expanding vascular stent based on a hybrid negative Poisson's ratio structure according to claim 6, characterized in that: The cell assembly is made of nickel-titanium alloy.

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