A method for preparing a tubular stent based on melt near-field direct writing technology

Abstract

The application discloses a kind of tubular stent preparation methods based on melt near-field direct writing technology. Using melt near-field direct writing technology, on the basis of precise control of jet deposition, tubular stents with different fiber structures are prepared. In view of the complexity of the preparation of the tubular stent with different structures at present, by deconstructing its structure form, the original three-dimensional tubular stent is converted into a two-dimensional plane, expressed in the form of two-dimensional coordinates to more intuitively understand its structural characteristics and accurately design. At the same time, it is easier to realize various complex paths and patterns on the plane, thereby improving the degree of freedom of design. Through the idea of plane unfolding, a more simple and efficient calculation method can be derived, thereby constructing a series of relatively simple mathematical formulas to accurately control the geometric parameters of the stent and optimize the entire preparation process.

Description

Technical Field

[0001] This invention belongs to the field of micro / nanofiber material preparation, specifically relating to a method for preparing tubular scaffolds based on melt near-field direct writing technology. Background Technology

[0002] Melt near-field direct writing technology combines the advantages of electrospinning and fused deposition modeling, achieving high-precision (1–50 μm) fiber scaffold printing at the micrometer level. This technology provides a new method for constructing tissue engineering scaffold microstructures and proposes a new strategy for the preparation of biomedical materials. Among them, micrometer-sized fiber tubular scaffolds with controllable structures have attracted widespread attention and are currently a research hotspot and challenge. However, existing methods for path planning and printing of tubular scaffolds with different structures are quite complex, resulting in low freedom of design and printing of scaffold structures, which is not conducive to meeting the needs of tissue engineering tubular scaffolds. Summary of the Invention

[0003] The purpose of this invention is to provide a method for fabricating tubular scaffolds based on melt near-field direct writing technology. Addressing the complexity of fabricating tubular scaffolds with different structures, this method deconstructs the structure, transforming the originally three-dimensional tubular scaffold into a two-dimensional plane, expressing it in two-dimensional coordinates for a more intuitive understanding of its structural features and for refined design. Furthermore, it facilitates the realization of various complex patterns and paths on a plane, thereby increasing design freedom. Through the planar unfolding approach, simpler and more efficient calculation methods can be derived, leading to a series of relatively simple mathematical formulas. This enables precise control of the scaffold's geometric parameters and optimizes the entire fabrication process. Using melt near-field direct writing technology, tubular scaffolds with different fiber structures are fabricated based on precise control of jet deposition.

[0004] To solve the above technical problems, the following technical solution is adopted:

[0005] A method for fabricating a tubular scaffold based on melt near-field direct writing technology, characterized by comprising the following steps:

[0006] Step 1: By deconstructing the tubular support structure design, it is unfolded from a three-dimensional structure into a two-dimensional planar form, which facilitates an intuitive understanding of its structural characteristics;

[0007] Step 2: Mark the path trajectory on the two-dimensional planar diagram unfolded in Step 1. Based on the path trajectory, decompose the overall two-dimensional planar structure into multiple identical units. By cyclically copying the units, construct the overall two-dimensional planar structure.

[0008] Step 3: Based on the units disassembled in Step 2, establish corresponding parameters to more accurately analyze structural features; construct a mathematical mapping relationship between parameters and path trajectories within each unit, that is, map changes in parameters to corresponding changes in path trajectories using mathematical algorithms, thereby describing and connecting the designed tubular support structure and the path in the printing process; with the assistance of the mathematical mapping relationship, the units are cyclically copied using programming software;

[0009] Step 4: Select a high-molecular polymer material and fabricate a tubular scaffold using a melt near-field direct writing device. The printing accuracy of melt near-field direct writing is affected by many process parameters (such as temperature, voltage, and air pressure). The critical translation speed is an important indicator reflecting the interaction of various process parameters. When the receiving plate moving speed is equal to the jet speed, the jet is perpendicular to the receiving plate, and the fiber is straight. When the receiving plate speed is greater than or less than the critical translation speed, the jet will lag, resulting in fiber deposition deviation or the printed fiber will be coiled. Therefore, it is crucial to control the jet deposition by adjusting the receiving plate speed. Traditional tubular scaffold printing requires calculating both the X-axis translation speed and the rotation speed of the receiving tube, which is quite cumbersome. In this invention, the three-dimensional printing of the tubular scaffold is transformed into planar printing by unfolding a two-dimensional plane. The rotation speed of the receiving tube can be equated to the Y-axis translation speed in planar printing. At the same time, only the speed in the control programming software is needed to match the resultant speed of the X and Y axes. Therefore, a similar k*critical translation speed (k∈(1~1.25)) can be used for printing.

[0010] After optimization, in step one, a three-dimensional graphic of the tubular support is first drawn. By deconstructing the structural design of the tubular support, the three-dimensional graphic is transformed into a two-dimensional planar form.

[0011] After optimization, in step one, the two-dimensional planar diagram includes, but is not limited to, the three nonlinear structures: rhombus, square, and self-expanding structure.

[0012] After optimization, in step three, corresponding parameters are set based on the units disassembled in step two; (1) The parameters set for the rhombus structure include the receiving tube radius r, the number of pivot points n, and the number of cycles R. m X-axis movement distance L X The single-trip travel distance L of the R-axis Y (2) The parameters set for the grid structure include the receiving tube radius r, the radial spacing L of the R-axis. S X-axis movement distance L X unit distance L in the X-axis direction unit , coefficient a; (3) The parameters set for the self-expanding structure include the tube radius r, the long side p of the path, and the short side q of the path.

[0013] After optimization, in step three, a mathematical mapping relationship between parameters and path trajectories within each unit is established to describe and connect the designed support structure and the path in the printing process; (1) Mathematical relationship between rhombus structure parameters: number of cycles R m That is, the number of revolutions is determined by the number of pivot points n, and the single-trip distance L along the R-axis. Y It is the ratio of the receiver tube circumference to the number of cycles R. m The product of the two, the winding angle θ is the distance L moved along the R-axis. Y Distance L along the X-axis X The ratio of; (2) Mathematical relationship between grid structure parameters: X-axis movement distance L X L is the unit distance traveled in the X-axis direction. unit The product of the coefficient a and the radial spacing L along the R-axis. S Related to the number of pivot points n; (3) Mathematical relationship between the parameters of the self-expanding structure: The ratio of the circumference of the receiving tube to the sum of the long side p and the short side q of the path is an integer.

[0014] After optimization, in step three, based on mathematical mapping relationships, the units are cyclically copied using programming software to construct a two-dimensional planar overall structure, generating instructions that can be read by the motion control system for path control.

[0015] After optimization, in step four, the polymer masterbatch is loaded into a spinning syringe, and a tubular scaffold is prepared using melt near-field direct writing technology; the polymer masterbatch can be one of polycaprolactone, polyurethane, polylactic acid, etc.

[0016] After optimization, if polycaprolactone is selected as the material, the spinning parameters for melt near-field direct writing are: heating temperature 80 ℃, voltage 4.5 kV, gas pressure 0.2 MPa, receiving distance 2.5 mm, receiving tube radius 1.5 mm, stainless steel needle type 25 G with an inner diameter of 0.26 mm and an outer diameter of 0.51 mm; if polyurethane is selected as the material, the spinning parameters for melt near-field direct writing are: heating temperature 175 ℃, receiving tube temperature 60 ℃, voltage 4.5 kV, gas pressure 0.15 MPa, receiving distance 3 mm, receiving tube radius 1.5 mm, stainless steel needle type 25 G with an inner diameter of 0.26 mm and an outer diameter of 0.51 mm; if polylactic acid is selected as the material, the spinning parameters for melt near-field direct writing are: heating temperature 185 ℃, receiving tube temperature 60 ℃, voltage 2.7 kV, gas pressure 0.05 MPa, receiving distance 1.75 mm, receiving tube radius 1.5 mm. The stainless steel needle is model 25 G, with an inner diameter of 0.26 mm and an outer diameter of 0.51 mm.

[0017] After optimization, step four, ensuring precise jet deposition, is crucial for the accurate fabrication of tubular scaffolds. Traditional tubular scaffold printing requires separate calculations of the X-axis translational speed and the rotational speed of the receiving tube, necessitating precise matching of these two speeds. Otherwise, fiber deposition may deviate, resulting in inaccurate fabrication of the tubular scaffold, and this process is quite cumbersome. In this invention, the three-dimensional printing of tubular scaffolds is transformed into planar printing through a two-dimensional planar unfolding approach. The rotational speed of the receiving tube is converted into the Y-axis translational speed in planar printing. Furthermore, only the speed control software is needed to match the combined speed of the X and Y axes, simplifying the process. The combined speed generated by the X-axis and Y-axis translational speeds is the speed required to fabricate the tubular scaffold. An important indicator in planar printing is the critical translational speed. At this speed, the fibers are in a straight line. Speeds greater than or less than the critical translational speed will cause jet lag, leading to fiber deposition deviation or curled printed fibers. During planar printing, k*critical translational speed is used to fabricate the scaffold depending on the specific circumstances. Therefore, the fabrication of tubular scaffolds can also adopt a similar k* critical translation velocity (k∈(1~1.25)) as that of planes to ensure the accurate printing of tubular scaffolds.

[0018] After optimization, in step three, the combined speed (F) of the translational speed and rotational speed of the receiving tube is 300 mm / min.

[0019] After optimization, in step two: based on the summarized formula, it can be calculated that when the number of diamond-shaped pivot points is 10, the number of cycles is 2.1, the length of the tubular support is 19.78 mm, and the angle of the resulting fiber membrane structure is 45°.

[0020] After optimization, in step two: based on the summarized formula, it can be calculated that when the radius of the grid structure receiving tube is 1.5 mm and the number of pivot points is 20, the radial interval of the R-axis is 0.942 mm, the moving distance of the X-axis is 20 mm, the unit moving distance in the X-axis direction is 1 mm, and the coefficient is 20.

[0021] After optimization, in step two: based on the summarized formula, it can be calculated that when the radius of the self-expanding structure receiving tube is 1.5 mm, the long side of the path is 0.9 mm and the short side of the path is 0.67 mm.

[0022] The above technical solution has the following beneficial effects:

[0023] The design and printing freedom of tubular support structures are increased, which can meet the complexity and personalization requirements of tubular support structures in specific application scenarios.

[0024] Optimizing the printing process and increasing printing flexibility can improve production efficiency, which will help promote the widespread application and popularization of tubular stents. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings:

[0026] Figure 1 This is a two-dimensional planar diagram unfolded from the three-dimensional solid diagram described in step one;

[0027] Figure 2 This is the melt near-field direct writing device used in step three;

[0028] Figure 3 Electron microscope images of different tubular scaffold structures prepared in Example 1;

[0029] Figure 4 This is a diagram of the preparation process in Example 2. Detailed Implementation

[0030] This invention aims to provide a method for fabricating tubular scaffolds based on melt near-field direct writing technology. By transforming the tubular scaffold from a three-dimensional structure to a two-dimensional plane, a simpler calculation method is derived. Melt near-field direct writing technology is then used to achieve precise deposition of the jet, thereby fabricating different tubular fiber structures.

[0031] The melt near-field direct writing device includes a melt spinning injector 1, a ceramic heat-conducting cylinder and heating ring 2, an insulating sleeve 3, a receiving tube 4, a temperature control device for melting the polymer 5, a pneumatic device for extruding the polymer 6, a high-voltage power supply for stretching to form a jet 7, and a computer device for control 8. The receiving tube 4 is connected to a slide table, and its movement is precisely controlled by a computer program.

[0032] The invention will be further described below with reference to specific embodiments:

[0033] Example 1

[0034] Step 1: By deconstructing the tubular support structure design, it is unfolded from a three-dimensional solid structure into a two-dimensional planar form to facilitate intuitive understanding of its structural characteristics. In this invention, it mainly includes, but is not limited to, the following three non-linear structures: rhombus, square, and self-expanding structure.

[0035] Step 2: Mark the path trajectory on the two-dimensional planar diagram unfolded in Step 1. Based on the idea of ​​unfolding the two-dimensional planar diagram, the overall structure is decomposed into multiple identical units according to the path trajectory. The overall structure is constructed by iteratively copying the units.

[0036] Step 3: Using the units disassembled in Step 2, establish corresponding parameters to more accurately analyze structural features. To fabricate a precise tubular scaffold, it is necessary to construct a mathematical mapping relationship between parameters and path trajectories within each unit. This involves using mathematical algorithms to map changes in parameters to corresponding changes in the path trajectory, thereby describing and connecting the designed scaffold structure with the path during the printing process. The parameters set for the rhombus structure include the receiving tube radius (r), the number of pivot points (n), and the number of loops (R). m ), X-axis movement distance (L) X ), R-axis movement distance (L) Y ), winding angle (θ). Number of cycles (R) m The number of revolutions is determined by the sum of the number of pivot points (n) and a natural number ξ (as shown in Formula 1), and the single-trip distance (L) along the R-axis. Y ) is the ratio of the receiver tube circumference to the number of cycles (R) m The product of (as in Formula 2), the winding angle (θ) is the distance traveled one way along the R-axis (L). Y ) and X-axis movement distance (L) X The ratio of (e.g., Formula 3). With the aid of mathematical mapping relationships, the cyclic replication of units is achieved through programming software.

[0037] (ξ∈Z) Formula 1

[0038] Formula 2

[0039] Formula 3

[0040] The parameters set for the grid structure include the receiver tube radius (r), the radial spacing along the R-axis (L). S ), X-axis movement distance (L) X ), unit distance traveled in the X-axis direction (L) unit ), coefficient (a). X-axis movement distance (L) X ) is the unit distance moved in the X-axis direction (L) unit The product between () and coefficient (a) (as in Formula 4), the radial interval of the R-axis (L) S The number of pivot points (n) is related to the number of pivot points (as shown in Formula 5).

[0041] Formula 4

[0042] Formula 5

[0043] The parameters set for the self-expanding structure include the receiving tube radius (r), the long side of the path (p), and the short side of the path (q). The ratio of the receiving tube circumference to the sum of the long side of the path (p) and the short side of the path (q) is an integer (as shown in Formula 6).

[0044] Formula 6

[0045] Step 4: Spinning is performed using a melt near-field direct writing device. Based on the formula obtained in Step 2 and combined with a computer numerical control system, precise jet deposition is achieved to prepare different fiber structures. Polycaprolactone masterbatch is placed into a spinning injector, which is then fixed with a heating sleeve. A temperature control chamber is used to apply temperature to the heating coil inside the heating sleeve, melting the polycaprolactone within the injector. A pneumatic device is connected above the spinning injector, and a high-pressure device is connected to the needle. Through the combined action of air pressure and voltage, the molten polymer forms a uniform jet and deposits onto the receiving tube. In this step, the polycaprolactone is heated to 80 °C, the applied voltage is 4.5 kV, the air pressure is 0.2 MPa, the receiving distance is 2.5 mm, the receiving tube radius is 1.5 mm, and the stainless steel needle is 25 G (inner diameter 0.26 mm, outer diameter 0.51 mm).

[0046] The printing accuracy of near-field direct-write melt printing is affected by numerous process parameters (such as temperature, voltage, and air pressure). The critical translation speed is an important indicator reflecting the interaction of these process parameters. When the receiving plate's moving speed equals the jet speed, the jet is perpendicular to the receiving plate, and the fiber is straight. When the receiving plate speed is greater than or less than the critical translation speed, the jet will lag, resulting in fiber deposition deviation or the printed fiber being curled. Therefore, controlling the jet deposition by adjusting the receiving plate speed is crucial. Traditional tubular support printing requires calculating both the X-axis translation speed and rotation speed separately, which is quite cumbersome. In this invention, the three-dimensional printing of tubular supports is transformed into planar printing by using the concept of two-dimensional plane unfolding. The rotation speed of the receiving tube can be equated to the Y-axis translation speed in planar printing. At the same time, only the speed in the control software is needed to match the combined speed of the X and Y axes. Therefore, a similar k*critical translation speed (k∈(1~1.25)) can be used for printing.

[0047] After resolving the relationship between the support design parameters and determining the spinning parameters, the motion control system generates instructions that can be read by the programming software, thereby achieving path control.

[0048] In this step, the number of pivot points (n) in the diamond grid is 10. According to the formula, the number of cycles (R) can be calculated. m The value is 2.1, and the length of the tubular stent (L) is 2.1. XThe diameter of the fiber membrane is 19.78 mm, and the angle (θ) of the resulting fiber membrane structure is 45°. The radius of the grid structure receiving tube is 1.5 mm, the number of pivot points (n) is 40, and the radial spacing of the R-axis (L) is... S The distance the X-axis moves is 0.5 mm, and the distance the X-axis moves is L. X The unit movement distance (L) in the X-axis direction is 26 mm. unit The radius of the self-expanding structure receiving tube is 1.5 mm, the long side (p) of the path is 0.9 mm, and the short side (q) of the path is 0.67 mm.

[0049] Example 2

[0050] Step 1: By deconstructing the tubular support structure design, it is unfolded from a three-dimensional structure into a two-dimensional planar form, which facilitates intuitive understanding of its structural characteristics and simplifies its structure. In this invention, it mainly includes, but is not limited to, the following three non-linear structures: rhombus, square, and self-expanding structure.

[0051] Step 2: Mark the path trajectory on the two-dimensional planar diagram unfolded in Step 1. Based on the idea of ​​unfolding the two-dimensional planar diagram, the overall structure is decomposed into multiple identical units according to the path trajectory. The overall structure is constructed by iteratively copying the units.

[0052] Step 3: Using the units disassembled in Step 2, establish corresponding parameters to more accurately analyze structural features. To fabricate a precise tubular scaffold, it is necessary to construct a mathematical mapping relationship between parameters and path trajectories within each unit. This involves using mathematical algorithms to map changes in parameters to corresponding changes in the path trajectory, thereby describing and connecting the designed scaffold structure with the path during the printing process. The parameters set for the rhombus structure include the receiving tube radius (r), the number of pivot points (n), and the number of loops (R). m ), X-axis movement distance (L) X ), R-axis movement distance (L) Y ), winding angle (θ). Number of cycles (R) m The number of revolutions is determined by the sum of the number of pivot points (n) and a natural number ξ (as in Formula 1), and the single-trip distance (L) along the R-axis. Y ) is the ratio of the receiver tube circumference to the number of cycles (R) m The product of (as in Formula 2), the winding angle (θ) is the distance traveled one way along the R-axis (L). Y ) and X-axis movement distance (L) X The ratio of (e.g., Formula 3). With the aid of mathematical mapping relationships, the cyclic replication of units is achieved through programming software.

[0053] (ξ∈Z) Formula 1

[0054] Formula 2

[0055] Formula 3

[0056] The parameters set for the grid structure include the receiver tube radius (r), the radial spacing along the R-axis (L). S ), X-axis movement distance (L) X ), unit distance traveled in the X-axis direction (L) unit ), coefficient (a). X-axis movement distance (L) X ) is the unit distance moved in the X-axis direction (L) unit The product between () and coefficient (a) (as in Formula 4), the radial interval of the R-axis (L) S The number of pivot points (n) is related to the number of pivot points (as shown in Formula 5).

[0057] Formula 4

[0058] Formula 5

[0059] The parameters set for the self-expanding structure include the receiving tube radius (r), the long side of the path (p), and the short side of the path (q). The ratio of the receiving tube circumference to the sum of the long side of the path (p) and the short side of the path (q) is an integer (as shown in Formula 6).

[0060] Formula 6

[0061] Step 4: Spinning is performed using a melt near-field direct writing device. Based on the formula obtained in Step 2 and combined with a computer numerical control system, precise jet deposition is achieved to prepare different fiber structures. Polyurethane masterbatch is placed into a spinning injector, which is then fixed with a heating sleeve. A temperature control chamber is used to apply temperature to the heating coil inside the heating sleeve, melting the polyurethane within the spinning injector. A pneumatic device is connected above the spinning injector, and a high-pressure device is connected to the needle. Through the combined action of air pressure and voltage, the molten polymer forms a uniform jet and deposits onto the receiving tube. In this step, the polyurethane heating temperature is 175 ℃, the receiving tube temperature is 60 ℃, the applied voltage is 4.5 kV, the air pressure is 0.2 MPa, the receiving distance is 2.5 mm, the receiving tube radius is 1.5 mm, and the stainless steel needle is 30 G (inner diameter 0.16 mm, outer diameter 0.31 mm).

[0062] The printing accuracy of near-field direct-write melt printing is affected by numerous process parameters (such as temperature, voltage, and air pressure). The critical translation speed is an important indicator reflecting the interaction of these process parameters. When the receiving plate's moving speed equals the jet speed, the jet is perpendicular to the receiving plate, and the fiber is straight. When the receiving plate speed is greater than or less than the critical translation speed, the jet will lag, resulting in fiber deposition deviation or the printed fiber being curled. Therefore, controlling the jet deposition by adjusting the receiving plate speed is crucial. Traditional tubular support printing requires calculating both the X-axis translation speed and rotation speed separately, which is quite cumbersome. In this invention, the three-dimensional printing of tubular supports is transformed into planar printing by using the concept of two-dimensional plane unfolding. The rotation speed of the receiving tube can be equated to the Y-axis translation speed in planar printing. At the same time, only the speed in the control software is needed to match the combined speed of the X and Y axes. Therefore, a similar k*critical translation speed (k∈(1~1.25)) can be used for printing.

[0063] After resolving the relationship between the support design parameters and determining the spinning parameters, the motion control system generates instructions that can be read by the programming software, thereby achieving path control.

[0064] In this step, the number of pivot points (n) in the diamond grid is 8. The number of cycles (R) can be calculated using the formula. m The value is 8.125, and the length of the tubular stent (L) is... X The diameter of the fiber membrane is 20.41 mm, and the angle (θ) of the resulting fiber membrane structure is 75°. The radius of the grid structure receiving tube is 1.5 mm, the number of pivot points (n) is 40, and the radial spacing of the R-axis (L) is... S 0.21 mm, X-axis movement distance (L) X The unit movement distance (L) in the X-axis direction is 20 mm. unit The radius of the self-expanding structure receiving tube is 1.5 mm, the long side (p) of the path is 1.41 mm, and the short side (q) of the path is 0.47 mm.

[0065] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A method for fabricating a tubular scaffold based on melt near-field direct writing technology, characterized in that... The process includes the following steps: Step 1: Deconstruct the tubular support structure design, unfolding it from a three-dimensional structure into a two-dimensional planar form; Step 2: Mark the path trajectory on the two-dimensional planar diagram unfolded in Step 1. Based on the path trajectory, decompose the overall two-dimensional planar structure into multiple identical units. By iteratively copying the units, the overall two-dimensional planar structure is constructed; Step 3: Establish corresponding parameters for the units decomposed in Step 2; construct a mathematical mapping relationship between the parameters within each unit and the path trajectory; use mathematical algorithms to map changes in parameters to corresponding changes in the path trajectory, thereby describing and connecting the designed tubular support structure with the path during the printing process; With the aid of mathematical mapping relationships, the unit is cyclically copied using programming software; Step 4: Select a high molecular polymer material and prepare a tubular scaffold using a melt near-field direct writing device; Transform the three-dimensional printing of the tubular scaffold into planar printing by unfolding it into a two-dimensional plane, and make the rotation speed of the receiving tube equal to the Y-axis translation speed in planar printing. The resultant speed of the X and Y axes can be matched by controlling the speed in the programming software. There is no need to calculate the X-axis translation speed and the rotation speed of the receiving tube separately. That is, the printing is carried out using the k*critical translation speed equivalent to planar printing, k∈(1~1.25).

2. The method for fabricating a tubular scaffold based on melt near-field direct writing technology according to claim 1, characterized in that: In step one, a three-dimensional drawing of the tubular support is first drawn. By deconstructing the structural design of the tubular support, the three-dimensional drawing is transformed into a two-dimensional planar form.

3. The method for fabricating a tubular scaffold based on melt near-field direct writing technology according to claim 1, characterized in that: In step one, the two-dimensional planar form is a rhombus, a square, or a self-expanding structure.

4. The method for fabricating a tubular scaffold based on melt near-field direct writing technology according to claim 3, characterized in that: In step three, corresponding parameters are set using the units disassembled in step two; (1) The parameters set for the rhombus structure include the receiving tube radius r, the number of pivot points n, and the number of cycles R. m X-axis movement distance L X The single-trip travel distance L of the R-axis Y (2) The parameters set for the grid structure include the receiving tube radius r, the radial spacing L along the R axis. S X-axis movement distance L X unit distance L in the X-axis direction unit , coefficient a; (3) The parameters set for the self-expanding structure include the tube radius r, the long side p of the path, and the short side q of the path.

5. The method for fabricating a tubular scaffold based on melt near-field direct writing technology according to claim 4, characterized in that: In step three, a mathematical mapping relationship between parameters and path trajectories within each unit is established to describe and connect the designed support structure and the path in the printing process; (1) Mathematical relationship between rhombus structure parameters: number of cycles R m That is, the number of revolutions is determined by the number of pivot points n, and the single-trip distance L along the R-axis. Y It is the ratio of the receiver tube circumference to the number of cycles R. m The product of the two, the winding angle θ is the distance L moved along the R-axis. Y Distance L along the X-axis X The ratio of arctangent; (2) Mathematical relationship between grid structure parameters: X-axis movement distance L X L is the unit distance traveled in the X-axis direction. unit The product of the coefficient a and the radial spacing L along the R-axis. S Related to the number of pivot points n; (3) Mathematical relationship between the parameters of the self-expanding structure: The ratio of the circumference of the receiving tube to the sum of the long side p and the short side q of the path is an integer.

6. The method for fabricating a tubular scaffold based on melt near-field direct writing technology according to claim 5, characterized in that: In step three, based on mathematical mapping relationships, the units are cyclically copied using programming software to construct a two-dimensional planar overall structure, generating instructions that the motion control system can read for path control.

7. The method for fabricating a tubular scaffold based on melt near-field direct writing technology according to claim 1, characterized in that: In step four, the polymer masterbatch is loaded into a spinning syringe, and a tubular scaffold is prepared using melt near-field direct writing technology; the polymer masterbatch can be one of polycaprolactone, polyurethane, or polylactic acid.

8. The method for fabricating a tubular scaffold based on melt near-field direct writing technology according to claim 7, characterized in that: If polycaprolactone is selected as the material, the spinning parameters for melt near-field direct writing are: heating temperature 80 ℃, voltage 4.5 kV, gas pressure 0.2 MPa, receiving distance 2.5 mm, receiving tube radius 1.5 mm, stainless steel needle type 25 G with an inner diameter of 0.26 mm and an outer diameter of 0.51 mm. If polyurethane is selected as the material, the spinning parameters for melt near-field direct writing are: heating temperature 175 ℃, receiving tube temperature 60 ℃, voltage 4.5 kV, gas pressure 0.15 MPa, receiving distance 3 mm, receiving tube radius 1.5 mm, stainless steel needle type 25 G with an inner diameter of 0.26 mm and an outer diameter of 0.51 mm. If polylactic acid is selected as the material, the spinning parameters for melt near-field direct writing are: heating temperature 185 ℃, receiving tube temperature 60 ℃, voltage 2.7 kV, gas pressure 0.05 MPa, receiving distance 1.75 mm, receiving tube radius 1.5 mm. The stainless steel needle is model 25 G, with an inner diameter of 0.26 mm and an outer diameter of 0.51 mm.

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