A gradient embossed expanded polytetrafluoroethylene implant and an embossing die therefor

Abstract

This utility model relates to the field of biomedical materials, and more particularly to a gradient embossed expanded polytetrafluoroethylene (e-PTFE) implant and its embossing mold. It is composed of at least two layers of e-PTFE sheets stacked together. The outer surface of the uppermost sheet is embossed with fine grooves 0.3-0.6 mm deep and 0.5-2.0 mm wide; the outer surface of the lowermost sheet is embossed with fine grooves 0.3-0.6 mm deep and 0.5-2.0 mm wide; the contact surface between every two adjacent sheets is embossed with coarse grooves 0.8-1.2 mm deep and 2.0-4.0 mm wide, and these coarse grooves penetrate the contact surface between the adjacent sheets. The technical problem this utility model aims to solve is that traditional e-PTFE implants suffer from drawbacks such as a smooth surface leading to limited tissue contact area, damage to the microporous structure, strong hydrophobicity making cell adhesion difficult, long integration cycle, and unstable processing effects, complex processes, and potential alteration of the material's chemical composition due to existing surface modification techniques.

Description

Technical Field

[0001] This utility model relates to the field of biomedical materials, and in particular to a gradient embossed expanded polytetrafluoroethylene implant and its embossing mold. Background Technology

[0002] Expanded polytetrafluoroethylene (e-PTFE) has become the preferred implant material in clinical practice due to its excellent chemical inertness, biological stability, and unique microporous structure. However, existing e-PTFE implants present several challenges. First, the surface of traditional e-PTFE implants is typically smooth, with a surface roughness Ra of only 0.5-1 μm, resulting in limited contact area with tissues. Furthermore, the unique microporous structure of e-PTFE is disrupted by the smooth surface. Second, e-PTFE itself is highly hydrophobic, with a water contact angle typically greater than 100°, making it difficult for cells to adhere and grow on its surface. These issues lead to a prolonged integration period between the implant and surrounding tissues, usually requiring 8-12 weeks, and increasing the risk of displacement and infection in dynamic environments.

[0003] While existing technologies offer methods for modifying the surface of expanded polytetrafluoroethylene (ePTFE) implants, such as surface roughening and coating, these methods often suffer from drawbacks such as unstable treatment effects, complex processes, and potential alterations to the material's chemical composition. Consequently, they struggle to effectively improve surface properties while maintaining the material's inherent superior performance. Therefore, developing an ePTFE implant that can effectively increase implant surface area, improve cell adhesion, shorten tissue integration time, and simultaneously preserve the material's excellent properties has significant clinical application value. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a gradient embossed expanded polytetrafluoroethylene (e-PTFE) implant and its embossing mold, which addresses the shortcomings of traditional expanded polytetrafluoroethylene (e-PTFE) implants, such as limited contact area with tissue due to smooth surface, damage to microporous structure, strong hydrophobicity making it difficult for cells to adhere, long integration cycle, and the unstable treatment effect, complex process and possible change of chemical composition of materials in existing surface modification technology.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: According to a first aspect of the present invention, a gradient embossed expanded polytetrafluoroethylene implant is provided, which is composed of at least two layers of expanded polytetrafluoroethylene sheets stacked together. The outer surface of the uppermost sheet is embossed with fine grooves with a depth of 0.3-0.6 mm and a width of 0.5-2.0 mm; the outer surface of the lowermost sheet is embossed with fine grooves with a depth of 0.3-0.6 mm and a width of 0.5-2.0 mm; and the contact surface of every two adjacent sheets is embossed with coarse grooves with a depth of 0.8-1.2 mm and a width of 2.0-4.0 mm, and the coarse grooves penetrate the contact surface of the adjacent sheets.

[0006] Optionally, the distribution density of the fine grooves is 20-30 grooves / cm²; the distribution density of the coarse grooves is 8-15 grooves / cm².

[0007] According to a second aspect of the present invention, an embossing mold for manufacturing the above-mentioned implant includes an end pressure plate assembly and a central pressure plate assembly. The end pressure plate assembly includes a top pressure plate and a bottom pressure plate. The working surface of the top pressure plate is provided with fine raised patterns with a depth of 0.3-0.6 mm. The working surface of the bottom pressure plate is provided with fine raised patterns with a depth of 0.3-0.6 mm. The central pressure plate assembly includes at least one detachable central pressure plate, both of which are provided with coarse raised patterns with a depth of 0.8-1.2 mm on both working surfaces. The number of central pressure plates and the number of sheet stacking layers satisfy the following condition: number of central pressure plates = number of sheet layers - 1.

[0008] Optionally, the fine pattern of the top pressure plate is configured to press the outer surface of the uppermost sheet; the fine pattern of the bottom pressure plate is configured to press the outer surface of the lowermost sheet; and the coarse pattern of each central pressure plate is configured to press the contact surface of adjacent sheets.

[0009] Optionally, the positional deviation of the coarse pattern on both sides of the central pressure plate is ≤0.05mm; the phase synchronization error of the pattern of adjacent central pressure plates is ≤0.1mm.

[0010] Optionally, the top pressure plate, bottom pressure plate, and central pressure plate may have a hexagonal honeycomb grid, a square grid, or a circular grid.

[0011] Optionally, the embossing die also includes a synchronous pressure system configured to simultaneously apply a vertical pressure of 1.0-3.0 MPa to the end pressure plate group and the central pressure plate group.

[0012] The advantages of this utility model are: 1. This utility model maintains the inherent chemical inertness and biological stability of e-PTFE through a physical embossing process rather than a chemical modification method, avoiding the biosafety risks that may be caused by the introduction of foreign substances, while ensuring the durability of the modification effect, which will not decay over time.

[0013] 2. The embossing process adopted in this utility model can precisely control the surface morphology by adjusting different embossing molds. The process is simple and controllable, and does not require expensive chemical reagents or complex equipment, thus having good cost-effectiveness.

[0014] 3. This invention significantly increases the effective contact area between the implant and human tissue by forming regular patterns on the implant surface, making it easier for cells to adhere, while maintaining the integrity of the microporous structure of expanded polytetrafluoroethylene, thus improving biocompatibility and tissue integration speed.

[0015] 4. The three-dimensional network structure formed by embossing in this invention effectively restricts the slippage of PTFE molecular chains, significantly improves the material's creep resistance, and enhances the stability of the implant in a dynamic environment.

[0016] 5. The unique gradient surface structure design of this utility model uses fine grooves on the surface to promote initial cell adhesion, and coarse grooves on the inner layer to provide space for blood vessel ingrowth. This realizes the functional hierarchy of "surface-inner layer", simulates the natural gradient characteristics of human tissue interface, and guides the layered growth of cells and blood vessels. It is particularly suitable for complex implantation scenarios that require multi-tissue integration. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the expanded polytetrafluoroethylene implant structure with two sheets according to this utility model; Figure 2 A schematic diagram of the expanded polytetrafluoroethylene implant with two sheets and its embossing mold for this utility model; Figure 3 A schematic diagram of the expanded polytetrafluoroethylene implant with four sheets and its embossing mold for this utility model; Figure 4 This is a SEM image of the expanded polytetrafluoroethylene sheet described in this utility model; Figure 5 This is a schematic diagram of the embossing mold described in this utility model.

[0019] In the diagram: 1. Expanded polytetrafluoroethylene sheet; 2. Top pressure plate; 3. Bottom pressure plate; 4. Central pressure plate. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] Example 1

[0022] like Figures 1-5 As shown, a gradient embossed expanded polytetrafluoroethylene (ePTFE) implant is composed of at least two layers of ePTFE sheets 1 stacked together. The outer surface of the uppermost sheet is embossed with fine grooves 0.5 mm deep and 1.0 mm wide, with a distribution density of 25 grooves / cm². The outer surface of the lowermost sheet is also embossed with fine grooves 0.5 mm deep and 1.0 mm wide, with a distribution density of 25 grooves / cm². These fine grooves increase the surface roughness of the implant, promoting tissue growth and cell adhesion, and improving the integration of the implant with surrounding tissues.

[0023] On the contact surface of every two adjacent sheets, coarse grooves with a depth of 1.0 mm and a width of 3.0 mm are embossed, with a distribution density of 10 grooves / cm². These coarse grooves penetrate the contact surface of adjacent sheets, forming a connected channel structure. The design of the coarse grooves creates an interconnected spatial network within the implant, which is beneficial for fluid circulation and tissue ingrowth, while also enhancing the bonding strength between the layers of the implant.

[0024] This gradient embossing design, with a surface of fine grooves and an interior of coarse grooves, creates a gradually increasing pore gradient from the outside to the inside. This better mimics the natural structure of human tissue and improves the biocompatibility and tissue integration of the implant.

[0025] like Figure 1 and Figure 2 As shown, in one embodiment, the implant sheet has two layers, and the embossing mold for manufacturing the implant has three pressure plates.

[0026] like Figure 3 As shown, in one embodiment, the implant sheet has four layers, and the embossing mold for manufacturing the implant has five pressure plates.

[0027] Example 2

[0028] The embossing mold for manufacturing the gradient embossed expanded polytetrafluoroethylene implant in Embodiment 1 includes an end pressure plate assembly and a central pressure plate assembly. The end pressure plate assembly includes a top pressure plate 2 and a bottom pressure plate 3. The working surface of the top pressure plate 2 is provided with fine raised patterns with a depth of 0.5 mm for pressing the outer surface of the uppermost sheet. The working surface of the bottom pressure plate 3 is provided with fine raised patterns with a depth of 0.5 mm for pressing the outer surface of the lowermost sheet.

[0029] The central pressure plate assembly includes at least one removable central pressure plate 4, both of which have coarse raised patterns with a depth of 1.0 mm on both working surfaces for pressing the contact surfaces of adjacent sheets. The number of central pressure plates 4 is related to the number of sheet stacking layers as follows: number of central pressure plates = number of sheet layers - 1. For example, when fabricating a three-layer sheet implant, two central pressure plates are required.

[0030] In a preferred embodiment, the positional deviation of the double-sided coarse pattern on the central pressure plate 4 is controlled within 0.03 mm, and the phase synchronization error of the patterns on adjacent central pressure plates is controlled within 0.08 mm. This precise positional control ensures that the pressed grooves are accurately aligned, forming a continuous channel structure.

[0031] In another preferred embodiment, the top pressure plate 2, the bottom pressure plate 3, and the central pressure plate 4 are patterned with a hexagonal honeycomb mesh. This honeycomb structure provides a more uniform stress distribution and better mechanical properties. Furthermore, the pattern can also be designed as a square or circular mesh to suit different clinical application needs.

[0032] The embossing mold also includes a synchronous pressure system configured to simultaneously apply a vertical pressure of 2.0 MPa to both the end pressure plate group and the central pressure plate group. This synchronous pressure system ensures that each layer of sheet is subjected to uniform pressure during the pressing process, thereby producing an implant with a uniform structure and stable quality.

[0033] When using this embossing mold to fabricate the implant, firstly, expanded polytetrafluoroethylene (ePTFE) sheets are stacked sequentially according to the designed number of layers. Then, the stacked sheets are placed into the embossing mold, with the top pressure plate 2 and bottom pressure plate 3 located on the outer sides of the top and bottom layers, respectively, and the central pressure plate positioned between adjacent sheets. After activating the synchronous pressure system, each pressure plate simultaneously applies pressure to the sheets, pressing the pattern into the sheets to form corresponding groove structures. The sheets are then transferred to an oven under pressure, with the pressure value adjusted according to the required sheet hardness. A gradient temperature program is set in the oven for curing. After cooling to room temperature, the pressure plates are removed, resulting in an ePTFE sheet with a uniform pore structure.

[0034] This gradient-embossed expanded polytetrafluoroethylene (ePTFE) implant exhibits excellent tissue compatibility and biofusion properties, making it suitable for various soft tissue repair and reconstruction surgeries. Its unique gradient porosity structure promotes tissue ingrowth and vascularization, reducing postoperative complications and improving surgical success rates.

[0035] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A gradient embossed expanded polytetrafluoroethylene implant, comprising at least two layers of expanded polytetrafluoroethylene sheets stacked together, characterized in that: The outer surface of the topmost sheet is embossed with fine grooves 0.3-0.6 mm deep and 0.5-2.0 mm wide; The outer surface of the bottommost sheet is embossed with fine grooves 0.3-0.6 mm deep and 0.5-2.0 mm wide; The contact surfaces of every two adjacent sheets are embossed with coarse grooves that are 0.8-1.2 mm deep and 2.0-4.0 mm wide, and the coarse grooves penetrate the contact surfaces of the adjacent sheets.

2. The implant according to claim 1, characterized in that: The distribution density of the fine grooves is 20-30 grooves / cm. 2 The distribution density of the coarse grooves is 8-15 grooves / cm. 2 .

3. An embossing mold for manufacturing the implant according to any one of claims 1-2, comprising an end pressure plate assembly and a central pressure plate assembly, characterized in that: The end pressure plate assembly includes a top pressure plate and a bottom pressure plate; The working surface of the top pressure plate is decorated with fine raised patterns with a depth of 0.3-0.6mm; The working surface of the bottom pressure plate is decorated with fine raised patterns with a depth of 0.3-0.6mm; The central pressure plate assembly includes at least one detachable central pressure plate, both of which have coarse raised patterns with a depth of 0.8-1.2mm on both working surfaces; The number of central pressure plates and the number of sheet stacking layers satisfy the following condition: number of central pressure plates = number of sheet layers - 1.

4. The embossing mold according to claim 3, characterized in that: The fine pattern of the top pressure plate is configured to press the outer surface of the top sheet; The fine pattern of the bottom pressure plate is configured to press the outer surface of the bottom sheet; The coarse pattern of each central pressure plate is configured to press the contact surfaces of adjacent sheets.

5. The embossing mold according to claim 3, characterized in that: The positional deviation of the coarse pattern on both sides of the central pressure plate is ≤0.05mm; The phase synchronization error of the pattern on adjacent central pressure plates is ≤0.1mm.

6. The embossing mold according to claim 3, characterized in that: The top pressure plate, bottom pressure plate, and central pressure plate have hexagonal honeycomb grids, square grids, or circular grids.

7. The embossing mold according to claim 3, characterized in that: The embossing mold also includes a synchronous pressure system configured to simultaneously apply a vertical pressure of 1.0-3.0 MPa to the end pressure plate group and the central pressure plate group.

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