Selective densification of expanded polyethylene

Abstract

A method of densifying an expanded polyethylene (ePE) substrate, the method comprising providing an ePE substrate having a first density and a first size, selectively densifying a portion of the ePE substrate to form a densified portion of the ePE substrate, the densified portion of the ePE substrate having a second density greater than the first density, the densified part of the ePE base material is a densified pattern; and shrinking the ePE substrate to a second size such that the densified pattern is shrunk to a fine densified pattern, the second size being smaller than the first size, the fine densified pattern being smaller than the densified pattern.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 433,123, filed Dec. 16, 2022, which is incorporated herein by reference in its entirety for all purposes. Technical Field

[0003] The present disclosure generally relates to devices, systems, and methods for densifying expanded polyethylene (ePE). More specifically, the present disclosure relates to devices, systems, and methods for densifying expanded polyethylene (ePE) that can be used in medical devices. Background Art

[0004] Methods for processing materials can impart specific properties to the processed materials. These specific properties may be necessary for the processed materials to serve their intended uses, or may enable the processed materials to be used in new applications. The choice of processing method is important in various industries, including but not limited to the medical device industry, and more specifically, for implantable medical devices. However, processed materials may be used in various industries, and the same properties required in one industry may also be important in other industries.

[0005] Medical devices often need to incorporate microscopic features to assist in treatment or interact with small molecules in the body. For example, medical treatment may require a medical device to interact with cells for the treatment to be effective. In some examples, these microscopic features may need to be located within the lumen of the medical device. However, it is very difficult to provide precise and accurate features at small scales. What is needed is a material that can reliably provide precise and accurate features at small scales. Summary of the Invention

[0006] The present disclosure relates to methods for densifying ePE substrates, articles, and devices produced by such methods, where densification can include fine embossing or micro - embossing. For example, articles and devices produced by such methods include densifying selected portions of an ePE substrate to form a densification pattern, and then reducing the size of the ePE substrate to form a fine pattern that can exhibit a set of desired features. These desired fine - pattern features can include promoting tissue ingrowth, anti - thrombosis, anti - migration, and controlling the direction of laminar flow.

[0007] According to one example (“Example 1”), a method for densifying an expanded polyethylene (ePE) substrate includes: optionally, providing an ePE substrate having a first density and a first size; selectively densifying a portion of the ePE substrate to form a densified portion of the ePE substrate, the ePE substrate having a first density and a first size, the densified portion of the ePE substrate having a second density greater than the first density, the densified portion of the ePE substrate being a densification pattern; and shrinking the ePE substrate to a second size such that the densification pattern is reduced to a refined densification pattern, the second size being smaller than the first size, the refined densification pattern being smaller than the densification pattern.

[0008] According to a further example of Example 1 (“Example 2”), a portion of the ePE substrate is selectively densified by an embossing process.

[0009] According to a further example of Example 1 (“Example 3”), selectively densifying a portion of the ePE substrate further includes applying heat and pressure to the ePE substrate.

[0010] According to a further example of Example 3 (“Example 4”), applying heat and pressure to the ePE substrate includes contacting the ePE substrate with a component having a temperature of about 110 degrees Celsius to about 180 degrees Celsius.

[0011] According to a further example of Example 1 (“Example 5”), the method further includes forming the ePE substrate into an ePE article.

[0012] According to a further example of Example 5 (“Example 6”), the ePE substrate is formed into a medical device.

[0013] According to a further example of Example 6 (“Example 7”), the medical device includes an implantable medical device.

[0014] According to a further example of Example 1 (“Example 8”), shrinking the ePE substrate to the second size further includes applying heat to the ePE substrate.

[0015] According to a further example of Example 1 (“Example 9”), the shape of the refined densification pattern is the same as the shape of the densification pattern.

[0016] According to a further example of Example 1 (“Example 10”), the refined densification pattern is configured to promote tissue ingrowth.

[0017] According to a further example of Example 1 (“Example 11”), the refined densification pattern is configured for antithrombosis.

[0018] According to another example further to Example 1 (“Example 12”), the fine densification pattern is configured to direct laminar flow over the surface of the fine densification pattern.

[0019] According to one example (“Example 13”), a method of creating a pattern on an expanded polyethylene (ePE) substrate includes: optionally, providing an ePE substrate having a first density and a first size; applying heat and pressure to the ePE substrate using a patterning assembly, the ePE substrate having the first density and the first size; the patterning assembly selectively densifying a first portion of the ePE substrate to a second density such that the ePE substrate has a first densification pattern in its first portion; and shrinking the ePE substrate to a second size such that the first densification pattern is reduced to a second densification pattern having a set of features, wherein the second densification pattern is smaller than the first densification pattern.

[0020] According to another example further to Example 13 (“Example 14”), the patterning assembly for applying heat and pressure is a mandrel.

[0021] According to another example further to Example 14 (“Example 15”), the mandrel has a texture pattern and the first densification pattern is the corresponding texture pattern.

[0022] According to another example further to Example 13 (“Example 16”), applying heat and pressure to the ePE substrate includes contacting the ePE substrate with a patterning assembly at a temperature of about 110 degrees Celsius to about 180 degrees Celsius.

[0023] According to another example further to Example 13 (“Example 17”), the first densification pattern includes a first depth ratio, the second densification pattern includes a second depth ratio, and the first depth ratio and the second depth ratio are substantially the same.

[0024] According to one example (“Example 18”), an expanded polyethylene (ePE) article includes an ePE substrate formed as the ePE article, the ePE article including a fine pattern formed by a selective densification patterning and shrinking process.

[0025] According to another example further to Example 18 (“Example 19”), the fine pattern has a texture for anti-thrombosis.

[0026] According to another example further to Example 18 (“Example 20”), the fine pattern is configured to promote tissue ingrowth.

[0027] According to another example further to Example 18 (“Example 21”), the fine pattern is configured to direct laminar flow over the surface of the ePE article.

[0028] Another example further to Example 18 (“Example 22”), the fine pattern is configured to facilitate tearing of the ePE article along the propagation path.

[0029] Another example further to Example 18 (“Example 23”), the fine pattern is configured to facilitate anti-migration.

[0030] Another example further to Example 18 (“Example 24”), the fine pattern includes repeating shapes.

[0031] Another example further to Example 18 (“Example 25”), the fine pattern is a random pattern.

[0032] The above examples are merely examples and should not be construed as limiting or otherwise narrowing the scope of any inventive concept otherwise provided by the present disclosure. Although multiple examples are disclosed, other embodiments will be apparent to those skilled in the art from the following detailed description which shows and describes illustrative examples. Accordingly, the drawings and detailed description are considered to be illustrative in nature and not restrictive. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to assist in further understanding the present disclosure, which are incorporated into and constitute a part of the specification. The drawings show embodiments of the present disclosure and, together with the specification, are used to explain the principles of the present disclosure.

[0034] Figure 1 is a block diagram of a method 100 for densifying an expanded polyethylene (ePE) substrate according to some embodiments, the method including a providing step, a selective densifying step, and a shrinking step;

[0035] Figure 2A is a front view of one embodiment according to some embodiments, wherein the ePE substrate is provided in a first dimension, selectively densified, and then shrunk to a second dimension;

[0036] Figure 2B is according to some embodiments Figure 2A bottom view;

[0037] Figure 3 is according to some embodiments, Figure 1 block diagram of a method for densifying an expanded polyethylene (ePE) substrate, wherein the method further includes a forming step;

[0038] Figure 4 is a schematic view of one embodiment according to some embodiments, wherein the ePE substrate is formed into a tubular ePE article;

[0039] Figure 5is a block diagram of a method for creating a pattern on an expanded polyethylene (ePE) substrate, the method including a providing step, a applying heat and pressure step, and a shrinking step;

[0040] Figure 6 is, according to some embodiments, a side view of a method for creating a pattern on an expanded polyethylene (ePE) substrate in accordance with Figure 5 the method;

[0041] Figure 7 is, according to some embodiments, Figure 5 a block diagram of a method for creating a pattern on an ePE substrate, the method further including a forming step; and

[0042] Figure 8A and 8B is, according to some embodiments, a schematic view of an ePE substrate having a densified pattern. DETAILED DESCRIPTION

[0043] Definitions and Terms

[0044] The present disclosure is not intended to be read in a limiting manner. For example, the terms used in this application should be read broadly in the context of the meanings ascribed to these terms in the art.

[0045] For imprecise terms, the terms “about” and “approximately” may be used interchangeably to mean that a measured value includes the stated measured value and also includes any measured value that is reasonably close to the stated measured value. As understood and readily determinable by one of ordinary skill in the relevant art, there is a reasonably small deviation between a measured value that is reasonably close to the stated measured value and the stated measured value. For example, such a deviation may be attributable to measurement error, differences in calibration of measurement and / or manufacturing equipment, human error in reading and / or setting measurements, fine-tuning for measurement differences associated with other components to optimize performance and / or structural parameters, particular implementation scenarios, imprecise adjustment and / or manipulation of an object by a person or a machine, etc. If it is determined that the value of such a reasonably small difference is not readily determinable by one of ordinary skill in the relevant art, the terms “about” and “approximately” may be understood to mean plus or minus 10% of the stated value.

[0046] As used herein, the term “laminate” refers to a multi-layer film, composite material, or other material, such as, but not limited to, polymers (such as, but not limited to, elastomers, elastomeric materials, or non-elastomeric materials and combinations thereof).

[0047] As used herein, the term “film” generically refers to one or more of a film, composite material, or laminate.

[0048] As used herein, the term "biocompatible material" generally refers to any material having biocompatible properties, including synthetic materials (such as but not limited to biocompatible polymers) or biomaterials (such as but not limited to bovine pericardium). The biocompatible material may include a first membrane and a second membrane as described herein for various embodiments.

[0049] As used herein, the term "polyethylene" (PE) includes all types of polyethylene, including but not limited to expanded polyethylene (ePE).

[0050] As used herein, the term "selective densification" generally refers to densification at a predetermined location on a substrate, including various degrees of densification, including partial densification such that the substrate remains porous and open after densification, and full densification where the substrate has a closed microstructure. Selective densification may include but is not limited to densification through the thickness of the substrate or along the length of the substrate.

[0051] As used herein, the term "shrinkage" generally refers to a reduction in size such that the size of a substrate or pattern becomes smaller relative to its size prior to shrinkage.

[0052] As used herein, the term "reduction" generally refers to a decrease in the size of a substrate or pattern such that the size of the substrate or pattern becomes smaller relative to its size prior to reduction.

[0053] Description of Various Embodiments

[0054] Those skilled in the art will understand that the various aspects of the present disclosure can be implemented by any number of methods and devices configured to perform the desired functions. It should also be noted that the drawings referred to herein are not necessarily drawn to scale and may be enlarged to illustrate the various aspects of the present disclosure, and in this regard, the drawings should not be considered limiting.

[0055] The present disclosure relates to methods for densifying an ePE substrate, articles and devices produced by such methods, wherein densifying the ePE substrate may include fine embossing or micro-embossing. For example, articles and devices produced by such methods include selectively densifying a selected portion of the ePE substrate to produce a densification pattern on the ePE substrate, and then reducing the size of the ePE substrate to form a fine pattern that may exhibit a set of desired characteristics. These desired fine pattern characteristics may include promoting tissue ingrowth, anti-thrombosis, controlling the direction of laminar flow, etc.

[0056] Figure 1 The methods shown are given as examples of various features of the method, and although combinations of these shown features are clearly within the scope of the invention, this example and its illustration are not meant to limit the inventive concept provided herein to Figure 1Fewer features, additional features, or alternative features of one or more of the features shown.

[0057] Figure 1 is a block diagram of a method 100 for densifying an expanded polyethylene (ePE) substrate according to some embodiments. The method includes a providing step, a selective densifying step, and a shrinking step. The method 100 can be implemented in a variety of situations, including but not limited to medical devices, which can include implantable medical devices. Various forms of ePE can be implemented in the method, including but not limited to membranes, films, tapes, tubes, etc. Further understood is that the ePE can have various properties, including different thicknesses, fibril and node structures, porosities, densities, etc. Thus, the embodiments discussed herein are not limited to specific initial conditions or forms, but should be broadly understood to encompass any ePE starting material applicable to the method.

[0058] In some embodiments, as Figure 1 shown, the method 100 for densifying an ePE substrate includes: optionally, providing an ePE substrate 110 of a first size; selectively densifying a portion of the ePE substrate 120; and shrinking the ePE substrate to a second size 130.

[0059] Further referring to Figure 1 , the ePE substrate also has a first density. The ePE substrate also has a first porosity. The first size can be defined by one or both of a longitudinal dimension or a transverse dimension. The ePE substrate can be square, rectangular, or other shapes, and thus can include various other dimensions for determining the size of the substrate (e.g., radius, length, width, etc.).

[0060] Still referring to Figure 1 , selectively densifying a portion of the ePE substrate 120 can form a densified portion of the ePE substrate. Selective densification refers to densifying a portion of the ePE substrate, thereby increasing the density of the selectively densified substrate. In some embodiments, selective densification includes increasing the density while also maintaining the porosity of the substrate portion being selectively densified (e.g., not fully densified, thus retaining an open microstructure). In some embodiments, selective densification includes increasing the density without retaining porosity (e.g., fully densified, thus having no open microstructure). The portion of the substrate that is not selectively densified is the porous portion that defines the undensified portion. Selective densification can be performed through the thickness of the ePE substrate or along the length of the ePE substrate. The densified portion of the ePE may not be densified through the thickness of the ePE substrate, thereby retaining at least a portion of the porosity in the thickness of the ePE substrate. In some embodiments, the undensified portion of the ePE substrate can be selectively masked such that the undensified portion remains undensified and porous.

[0061] The densified portion of the ePE substrate may have a second density greater than the first density. In some embodiments, the densified portion of the ePE substrate may have a second porosity less than the first porosity. The second porosity may retain pores, but the pore size is reduced due to shrinkage. The location of the shrinkage and the pores may be controlled to a specific location or portion of the ePE substrate. The densified portion of the ePE substrate may adopt a densification pattern. The selective densification 120 of the ePE substrate may be performed on a single portion of the ePE substrate, or may be performed on more than one portion of the ePE substrate. The densified portion may be created at any location on the ePE substrate, including but not limited to the central portion, the left portion, or the right portion of the ePE substrate. In some other embodiments, the selective densification 120 of a portion of the ePE substrate may be performed on multiple portions of the ePE substrate. In some embodiments, the densified portion covers substantially the entire surface of the ePE substrate. In some other embodiments, the selective densification 120 of a portion of the ePE substrate may be performed in one or more directions among the longitudinal, transverse, or diagonal directions with respect to the axis of the ePE substrate. In some examples, a densified portion having a certain shape and depth is produced such that the densification pattern has a certain shape and depth. It should be understood that any densified shape or pattern is contemplated herein, not limited to those provided herein, and these examples are only examples of some possible shapes and patterns.

[0062] In some embodiments, a portion of the ePE substrate may be selectively densified 120 by embossing. Embossing the portion of the ePE substrate may produce a densification pattern having a portion of raised features and a portion of recessed features. In some other embodiments, the selective densification 120 of a portion of the ePE substrate includes applying heat and / or pressure to the ePE substrate. Applying heat and / or pressure to the ePE substrate may include bringing the ePE substrate into contact with a component. The component may be heated to around the glass transition temperature or the melting temperature of the ePE substrate, which may be between about 110 °C and about 180 °C. For example, the component may be heated to a temperature of about 110 °C to about 120 °C, about 120 °C to about 130 °C, about 130 °C to about 140 °C, about 140 °C to about 150 °C, about 150 °C to about 160 °C, about 160 °C to about 170 °C, or about 170 °C to about 180 °C. The component may be provided at any temperature suitable for forming the densification pattern. The component may be applied at a pressure higher than about 2 PSI. The applied pressure should ensure that the ePE substrate does not open or break. The component may contact the ePE substrate at any pressure suitable for forming the densification pattern. In some embodiments, heat and / or pressure may be applied to the ePE substrate at a constant value. In some other embodiments, heat and / or pressure may be applied to the ePE substrate at varying values. The selected temperature and / or pressure may affect the shape and depth of the densification pattern.

[0063] In some embodiments, embossing can be performed by manual embossing or automatic embossing. Embossing can be performed by an external device (not shown; for example, a soldering iron, a hot stamper, etc.). Embossing can be performed by an internal device (not shown; a heated mandrel, etc.). Embossing by an external device can selectively densify the outer surface portion of the ePE substrate. Embossing by an internal device can selectively densify the inner surface portion of the ePE substrate (for example, Figure 4 the inner cavity of the ePE article 430 in the tubular structure shown in

[0064] Still referring to Figure 1 , in some embodiments, after selectively densifying 120 a portion of the ePE substrate (for example, the central portion 227 of the ePE substrate (see Figure 2A ), the ePE substrate shrinks from a first size to a second size 130, and the second size is smaller than the first size. In some embodiments, shrinking the ePE substrate to the second size 130 causes the size of the densification pattern to decrease or shrink, thereby forming a fine densification pattern. The size of the fine densification pattern may be smaller than the size of the initial densification pattern. In some embodiments, the ability of the ePE substrate to retain pores after selective densification contributes to the shrinkage of the ePE substrate (including the densified portion and the non-densified portion of the ePE substrate). In these embodiments, the shrinkage ratios of the densified portion and the non-densified portion of the ePE substrate are different. For example, the shrinkage ratio of the non-densified portion may be greater than the shrinkage ratio of the selectively densified portion. For example, by providing an ePE substrate having fibrils oriented in a certain direction (for example, arranged substantially along a specific direction), proportional shrinkage can occur such that the ePE substrate is more likely to undergo proportional shrinkage in a direction perpendicular to the fibrils. In some embodiments, selectively densifying a portion of the ePE substrate can cause the non-densified portion of the ePE substrate to selectively shrink. Shrinkage may occur in the non-densified portions of the ePE substrate that still retain porosity after selective densification. Shrinkage may also occur throughout the thickness of the densified portion of the ePE substrate, thereby retaining porosity within a partial thickness range. In some embodiments, the ePE substrate is fully densified when it shrinks. In other embodiments, the ePE substrate may retain pores when it shrinks.

[0065] In some embodiments, the fine densification pattern has the same or substantially similar shape as the densification pattern. For example, if the shape of the densification pattern is a longitudinal rectangle, the fine densification pattern will maintain the shape of a longitudinal rectangle (see, for example, Figures 2A - 2B)。In this regard, the refined densified pattern can maintain the dimensional accuracy of the shape even after the size is reduced. In some other embodiments, the shape of the refined densified pattern is different from that of the densified pattern. In some other embodiments, the shape of the refined densified pattern may be a shape deformed from the shape of the densified pattern. In some embodiments, the refined densified pattern includes a certain depth. In some embodiments, the depth of the refined densified pattern can be the same as the depth of the densified pattern. In some other embodiments, the ratio of the depth of the densified pattern to the longitudinal axis of the ePE substrate is the same as the ratio of the depth of the refined densified pattern to the longitudinal axis of the smaller densified ePE substrate. In this regard, the refined densified pattern can also maintain the dimensional accuracy of the depth when the size is reduced. In some other embodiments, the relative surface area coverage of the densified pattern on the densified ePE substrate can be the same as the relative surface area coverage of the refined densified pattern on the smaller densified ePE substrate. In some embodiments, during the shrinkage process of the ePE substrate, the densified pattern shrinks to the refined densified pattern, such that the densified pattern shrinks proportionally with the ePE substrate.

[0066] In some embodiments, the refined densified pattern imparts a series of characteristics to the ePE substrate. In some embodiments, the refined densified pattern is configured to promote tissue ingrowth. In some embodiments, the refined densified pattern is configured for antithrombosis. In some embodiments, the refined densified pattern is configured to direct laminar flow over the surface of the refined densified pattern. More examples of this group of characteristics are described in Figures 8A - 8B .

[0067] In some embodiments, shrinking the densified ePE substrate to the second dimension 130 further includes applying heat to the densified ePE substrate. The densified ePE substrate can be heated to a temperature near its glass transition temperature or melting temperature, which can be between about 110°C and about 180°C. For example, the densified ePE substrate can be heated to a temperature of about 110°C to about 120°C, about 120°C to about 130°C, about 130°C to about 140°C, about 140°C to about 150°C, about 150°C to about 160°C, about 160°C to about 170°C, or about 170°C to about 180°C. In some embodiments, the ePE substrate is heated by a heating environment (e.g., an oven). In some embodiments, heating the ePE substrate can selectively densify the ePE substrate. In some embodiments, heating may cause the ePE substrate to shrink or retract naturally. The degree of shrinkage or retraction can match the degree of expansion of the ePE substrate. In some embodiments, the densified ePE substrate is shrunk to the second dimension 130 without constraint. In other embodiments, the densified ePE substrate is shrunk to the second dimension 130 while the densified ePE substrate is constrained in at least one dimension (e.g., longitudinally, transversely, etc.). For example, the ePE substrate can be constrained in the z-direction (e.g., the thickness direction) such that the ePE substrate can flow longitudinally and transversely when heated. The constraint in the z-direction can include positioning the ePE substrate between two plates (e.g., weighted plates) and placing a spacer having the same thickness as the ePE substrate between the two plates to constrain the z-direction of the ePE substrate.

[0068] In some embodiments, the densified ePE substrate is cooled after being heated. The densified ePE substrate can be cooled at room temperature, placed in an environment below room temperature (e.g., a refrigerator), or slowly cooled in an environment with a temperature higher than room temperature. In some embodiments, the cooling environment of the densified ePE substrate can be a stable temperature or a variable temperature. In some embodiments, the variable temperature of the environment allows the densified ePE substrate to cool at a controlled rate. The cooling rate of the densified ePE substrate can be constant or variable.

[0069] Figure 2A is a front view of one embodiment in accordance with some embodiments in which the ePE substrate 210 is provided in a first dimension L1, selectively densified, and then shrunk to a second dimension L2. In some embodiments, Figure 2A The examples in Figure 1 follow the method 100 as described above.

[0070] In Figure 2A the ePE substrate 210 has a first dimension L1. In some embodiments, this can follow Figure 1Method steps for providing an ePE substrate (110) of a first dimension. In the present embodiment, the first dimension L1 is defined as the horizontal direction (e.g., width), but the first dimension can also be defined by the longitudinal direction (e.g., height), the thickness direction (e.g., thickness), or any combination of the transverse, longitudinal, and thickness directions. In the present embodiment, the ePE substrate 210 is shown as a square, but other shapes of the ePE substrate 210 are also contemplated.

[0071] Further referring to Figure 2A , a portion of the ePE substrate 210 can be selectively densified to form an ePE substrate 220 having a densified portion. In some embodiments, the method of forming an ePE substrate 220 having a densified portion is substantially similar to the method steps of selectively densifying a portion of the ePE substrate 120 described in Figure 1 . The ePE substrate 220 having a densified portion includes a densification pattern 225, and the densification pattern 225 has a shape. In the present embodiment, the shape of the densification pattern 225 is a longitudinal rectangle. Other shapes of the densification pattern 225 can include, but are not limited to, circular, square, or triangular, etc. The shape can also extend along the transverse, diagonal, or any other direction. In the present embodiment, the densification pattern 225 is defined in the central portion 227 of the ePE substrate 220 having a densified portion. In other embodiments, the densification pattern 225 can also be produced in the left portion 221 of the ePE substrate 220 having a densified portion or the right portion 223 of the ePE substrate 220 having a densified portion, or at any position between the left portion 221 and the right portion 223. In the present embodiment, a portion of the ePE substrate 220 having a densified portion has a densification pattern 225, but in other embodiments, multiple densification patterns can be produced within the surface of the ePE substrate 220 having a densified portion. In the present embodiment, the ePE substrate 220 having a densified portion can shrink to an intermediate dimension LI. The intermediate dimension LI can be smaller than the first dimension L1. This dimensional change may be caused by a depth local change in the ePE substrate 220 having a densified portion due to the formation of the densification pattern 225, as shown in Figure 2B . In other embodiments, the intermediate dimension L1 can be the same as the first dimension L1.

[0072] Further referring to Figure 2A , the ePE substrate 220 having a densified portion can be reduced to a retracted ePE substrate 230. The retracted ePE substrate 230 has a second dimension L2. In some embodiments, this can follow Figure 1Method steps for shrinking the ePE substrate to a second dimension 130. In the present embodiment, the second dimension L2 is smaller than the first dimension L1. In the present embodiment, the second dimension L2 is also smaller than the intermediate dimension LI. Shrinking the ePE substrate 230 includes a fine densification pattern 235. In some embodiments, the size of the fine densification pattern 235 is smaller than the size of the densification pattern 225. In the present embodiment, the fine densification pattern 235 is generated from the densification pattern 225, and the fine densification pattern 235 is generated by shrinking an ePE substrate 220 having a densified portion. In the present embodiment, the fine densification pattern 235 retains the shape of the densification pattern 225. In the present embodiment, relative to the non-densified region of the ePE substrate 220, the fine densification pattern 235 also retains the same relative surface area coverage as the densification pattern 225. In other embodiments, it is contemplated that the fine densification pattern 225 has a shape or surface area coverage that is slightly different from the densification pattern 225. In some embodiments, it is contemplated that the fine densification pattern 235 is modified from the densification pattern 225. For example, the shape of the densification pattern 225 can be substantially square, while the shape of the densification pattern 235 can be substantially rectangular. Other shapes can also be considered, such as from a substantially circular densification pattern 225 to a substantially oval fine densification pattern 235. The change in shape can be to limit shrinkage in a certain direction, or can be achieved by providing an ePE substrate having fibrils oriented in a certain direction (e.g., substantially aligned along a specific direction), such that the ePE substrate is more likely to shrink proportionally in a direction perpendicular to the fibrils.

[0073] Figure 2B is according to some embodiments Figure 2ABottom view. The ePE substrate 210 shown in the figure has a first thickness T1. The ePE substrate 220 with a densified portion shown in the figure has an intermediate thickness TI and a densification pattern 225. In some embodiments, the densification pattern 225 may have a depression depth D1 that protrudes downward relative to the undensified portions (e.g., the left portion 221 and the right portion 223). This can make the intermediate thickness TI less than the first thickness T1 at the location of the densification pattern 225. In some embodiments, the depression depth D1 is less than the thickness of the ePE substrate 220 with the densified portion, such that a portion of this thickness remains porous. In the present embodiment, when the densification pattern 225 has a depression depth, the fine densification pattern 235 may have a depression depth D2. In some embodiments, the depression depth D2 may be the same as the depression depth D1. In other embodiments, the depression depth D2 may be further recessed downward such that the depression depth D2 is greater than the depression depth D1. In other embodiments, the depression depth D2 may retract such that the depression depth D2 is less than the depression depth D1. In this embodiment, due to the higher porosity of the undensified portions, the undensified portions (e.g., the left portion 221 and the right portion 223) can be operable to retract to a greater extent than the densified portion (e.g., the central portion 227). The higher porosity of the undensified portions causes them to at least partially retract when shrinking.

[0074] In other embodiments, the densification pattern 225 may protrude or extend outward relative to the undensified portions (e.g., the left portion 221 and the right portion 223). This can be achieved by forming the densification pattern 225 as described above and then masking the densification pattern 225 on the densified portion 220 of the ePE substrate 210. For example, this can be used for an angioplasty balloon such that the balloon has a protruding densification pattern 225 to grip the blood vessel during implantation.

[0075] Figure 3 is according to some embodiments, Figure 1 Block diagram of a method 300 for densifying an expanded polyethylene (ePE) substrate, where the method further includes a forming step. The method 300 can be implemented in a variety of situations, including but not limited to medical devices, which may include implantable medical devices. The method 300 includes a plurality of method steps, including optionally providing an ePE substrate 310 of a first size, selectively densifying a portion of the ePE substrate 320, shrinking the ePE substrate to a second size 330, and shaping the ePE substrate into an ePE article 340.

[0076] The method step of optionally providing an ePE substrate 310 of a first size can be related to the above regarding Figure 1The method steps for providing the ePE substrate 110 of the first dimension are substantially similar. The method steps for selectively densifying 320 a portion of the ePE substrate may be substantially similar to the method steps for selectively densifying 120 a portion of the ePE substrate described above with respect to Figure 1 The method steps for shrinking 330 the ePE substrate to the second dimension may be substantially similar to the method steps for shrinking 130 the ePE substrate to the second dimension described above with respect to Figure 1 The method steps for shrinking 130 the ePE substrate to the second dimension.

[0077] When forming 340 the ePE substrate into an ePE article, the ePE article may include, but is not limited to, a tubular structure or a flat structure. The ePE article may be formed into a medical device or a medical device component, or provided as a medical device or a medical device component. The medical device may include an implantable medical device. The medical device may be used for long-term implantation or short-term implantation (e.g., temporary implantation). The tubular structure may be implemented, for example, as a graft. The flat structure may be implemented, for example, as a hernia patch, a cardiovascular patch, a nerve membrane, etc. The medical device may also include a balloon (e.g., an angioplasty balloon, a urinary balloon, a stent deployment balloon) formed with a fine densification pattern, wherein the fine densification pattern helps to anchor the balloon to the tissue of the patient, thereby substantially fixing the balloon in place and preventing device displacement. In some embodiments, the ePE substrate may be formed 340 into an ePE article before the step of selectively densifying 320 a portion of the ePE substrate, such that the ePE article is selectively densified. In some embodiments, forming 340 the ePE substrate into an ePE article may be performed after the selective densification step but before shrinking 330 the ePE substrate to the second dimension, such that the ePE article is shrunk to the second dimension. In other embodiments, forming 340 the ePE substrate into an ePE article may be performed after shrinking 330 the ePE substrate to the second dimension, such that the ePE article is formed in the second dimension.

[0078] Figure 4 FIG. is an illustration of one embodiment of forming 330 a reduced ePE substrate 230 into an ePE article in the form of a tubular structure. This figure is a view of Figure 2A and 2BFurther description of the embodiments. The reduced ePE substrate 230 formed into a tubular structure ePE article 430 may further include winding the reduced ePE substrate 230 around a mandrel 410. The diameter of the mandrel 410 may be D1. When wound around the mandrel 410, the reduced ePE substrate 230 may be joined or coupled to itself by one of melt bonding, using an adhesive, or mechanical connection (such as using sutures) to form the tubular structure ePE article 430. In this embodiment, the smaller densified ePE substrate 235 is wound around the mandrel 410 such that the fine densification pattern is in a vertical orientation. In other embodiments, the smaller densified ePE substrate 235 is wound around the mandrel 410 such that the fine densification pattern 235 is in a transverse orientation. The tubular structure ePE article 430 may be a medical device, including but not limited to an implantable graft.

[0079] Figure 5 is a block diagram of a method 500 for generating a pattern on an expanded polyethylene (ePE) substrate according to some embodiments, the method including a providing step, a applying heat and pressure step, and a shrinking step. The method 500 may be implemented in a variety of situations, including but not limited to medical devices, which may include implantable medical devices.

[0080] In some embodiments, as Figure 5 shown, the method 500 for generating a pattern on an ePE substrate includes: optionally providing an ePE substrate 510 of a first size; applying heat and pressure 520 to the ePE substrate using a patterning assembly; and shrinking the ePE substrate to a second size 530.

[0081] Further referring to Figure 5 , when optionally providing the ePE substrate 510 of a first size, the ePE substrate further has a first density. The ePE substrate further has a first porosity. The first size may be defined by one or both of a longitudinal size or a transverse size. The ePE substrate may be square, rectangular, or other shapes.

[0082] Still referring to Figure 5 , applying heat and pressure 520 to the ePE substrate using a patterning assembly may include selectively densifying the ePE substrate with the patterning assembly. The definition of selective densification is the same as Figure 1is substantially similar to that described in. Heat and pressure can affect the degree of densification of the ePE substrate (e.g., through the thickness of the ePE substrate), and the pattern of the patterning component can include locations of densification (e.g., through the length of the ePE substrate). The patterning component can selectively densify a first portion of the ePE substrate to a second density such that the ePE substrate has a first densification pattern in the first portion of the ePE substrate. In some embodiments, the second density can be greater than the first density. In some embodiments, the patterning component for applying heat and pressure is a mandrel. In some embodiments, where the patterning component is a mandrel, the mandrel can have a texture pattern and the first densification pattern is a corresponding texture pattern (e.g., as Figure 6 shown).

[0083] In some embodiments, applying heat and pressure 520 to the ePE substrate using the patterning component further includes contacting the ePE substrate with the patterning component at a temperature near the glass transition temperature or melting temperature of the densified ePE substrate, which can be between about 110°C and about 180°C. For example, the densified ePE substrate can be heated to a temperature of about 110°C to about 120°C, about 120°C to about 130°C, about 130°C to about 140°C, about 140°C to about 150°C, about 150°C to about 160°C, about 160°C to about 170°C, or about 170°C to about 180°C. The component can be provided at any temperature suitable for forming the first densification pattern. The patterning component can be applied at a pressure above about 2 PSI. The applied pressure should ensure that the ePE substrate does not open or break. The patterning component can be provided at any pressure suitable for forming the first densification pattern. In some embodiments, heat and pressure can be applied to the ePE substrate at a constant value. In other embodiments, heat and pressure can be applied to the ePE substrate at variable values to produce the first densification pattern.

[0084] When heat and pressure 520 are applied to the ePE substrate using the patterning component, the microstructure of the ePE substrate may change. For example, the microstructure of the ePE substrate may contain node and fibril structures, thus forming a porous (e.g., microporous) structure. In some embodiments, when heat and pressure 520 are applied to the ePE substrate using the patterning component, the porosity of the microstructure may decrease while retaining some porosity as well as the node and fibril microstructure. In some embodiments, when heat and pressure 520 are applied to the ePE substrate using the patterning component, the density of the microstructure may remain substantially unchanged. In some embodiments, applying heat and pressure may form at least partially densified microstructures such that at least a portion of the node and fibril microstructures are densified and no longer define a porous microstructure. In other embodiments, the ePE substrate can be fully densified, thereby fully densifying the microstructure.

[0085] Still referring to Figure 5 , in some embodiments, after applying heat and pressure 520 to the ePE substrate using the patterned component, the ePE substrate is shrunk to a second dimension 530. In some embodiments, the ePE substrate is shrunk to the second dimension 530 such that the size of the first densification pattern is reduced or shrunk to a second densification pattern having a set of features, and the size of the second densification pattern is smaller than the first densification pattern. In some embodiments, when the ePE substrate is shrunk to the second dimension 530, the number of open spaces in the microstructure of the ePE substrate is reduced. In some embodiments, the shape of the second densification pattern is the same as the first densification pattern. In this regard, the second densification pattern substantially maintains the dimensional accuracy of the shape during size contraction. In other embodiments, the shape of the second densification pattern is slightly different from the first densification pattern. In other embodiments, the shape of the second densification pattern may be a modified shape of the first densification pattern. In some embodiments, the first densification pattern includes a depth. This depth can be a recess depth (e.g., protruding inward from the axis of the ePE substrate). The second densification pattern can maintain the same depth as the first densification pattern during contraction. However, the depth size of the first densification pattern can be different from the depth size of the second densification pattern. Instead, the depth of the second densification pattern can maintain a second depth ratio relative to the axis of the ePE substrate, and this second depth ratio is substantially the same as the first depth ratio of the first densification pattern relative to the axis of the ePE substrate. In this regard, the second densification pattern still maintains the dimensional accuracy of the depth during size contraction. In addition, the first densification pattern covers a first surface area of the ePE substrate. The second densification pattern can maintain the same surface area coverage as the first densification pattern. In other words, the surface area ratio between a set of densified portions of the ePE substrate in the second densification pattern and a set of non-densified portions of the ePE substrate can be the same as that in the first densification pattern.

[0086] Figure 6 is a side view of generating a pattern on an ePE substrate 610 according to some embodiments in accordance with the method of Figure 5 . In Figure 6 , the ePE substrate 610 is aligned with the patterned component 620. The patterned component 620 includes a pattern 625. In this embodiment, the pattern is a triangular pattern 625 having a raised area 621 and a recessed area 623. However, the pattern 625 can also take other shapes, including but not limited to circular patterns, square patterns, rectangular patterns, etc.

[0087] Continuing to refer to Figure 6, in the present embodiment, the ePE substrate 610 is shown in contact with the patterning component 620. When heat and pressure 615 are applied to the patterning component 620 to bring it into contact with the ePE substrate 610, the ePE substrate 610 is compressed. In some embodiments, the ePE substrate 610 becomes a densified ePE substrate 630. In some embodiments, the ePE substrate 610 is flexible such that when the heat and pressure 615 are removed, the densified ePE substrate 630 retains the first densification pattern 635. In this regard, the patterning component 620 can be used to generate the first densification pattern 635. In some embodiments, the first densification pattern 635 can correspond to the pattern 625 of the patterning component 620. In some embodiments, the first densification pattern 635 is a mirror image of the pattern 625 of the patterning component 620. In this embodiment, the first densification pattern 635 has a first raised region 631 and a first recessed region 633, which correspond to the raised region 621 and the recessed region 623 of the pattern 625.

[0088] Further reference Figure 6 , in some embodiments, after forming the densified ePE substrate 630 having the first densification pattern 635, the size of the densified ePE substrate 630 shrinks to a smaller densified ePE substrate 650. In some embodiments, the smaller densified ePE substrate 650 includes a second densification pattern 655. In some embodiments, the size of the first densification pattern 635 shrinks to the second densification pattern 655. The second densification pattern 655 can retain the same shape or features as the first densification pattern 635. In the present embodiment, the second densification pattern 655 includes a second raised region 651 and a second recessed region 653, which correspond to the first raised region 631 and the first recessed region 633 but are smaller in size. Additionally, the depth of the second densification pattern 655 is substantially the same as that of the first densification pattern 635. The second densification pattern 655 also maintains the same relative surface area coverage as the first densification pattern 635. In this regard, when the densified ePE substrate shrinks, both the depth and the shape of the second densification pattern 655 maintain dimensional accuracy.

[0089] Figure 7 is according to some embodiments, Figure 5 a block diagram of a method 700 for generating a pattern on an ePE substrate, the method further including a forming step. The method 700 can be implemented in a variety of situations, including but not limited to medical devices, which can include implantable medical devices.

[0090] Method 700 includes: optionally providing an ePE substrate 710 of a first size; applying heat and pressure to the ePE substrate using a patterning component 720; shrinking the ePE substrate to a second size 730; and forming the ePE substrate into an ePE article 740.

[0091] In some embodiments, the method step of optionally providing an ePE substrate 710 of a first size may be substantially similar to the method step of optionally providing an ePE substrate 510 of a first size as described above with respect to Figure 5 In some embodiments, the method step of applying heat and pressure to the ePE substrate using a patterning component 720 may be substantially similar to the method step of applying heat and pressure to the ePE substrate using a patterning component 520 as described above with respect to Figure 5 In some embodiments, the method step of shrinking the ePE substrate to a second size 730 may be substantially similar to the method step of shrinking the ePE substrate to a second size 530 as described above with respect to Figure 5 In some embodiments, the method step of shrinking the ePE substrate to a second size 530 may be substantially similar.

[0092] Further referring to Figure 7 , when forming the ePE substrate into an ePE article (740), the ePE article may include, but is not limited to, a tubular structure or a flat structure. The ePE article may be formed into a medical device or a medical device component, or provided as a medical device or a medical device component. The medical device or medical device component may be used for long-term implantation or short-term implantation. The medical device may include an implantable medical device. The tubular structure may be implemented as a graft, for example. The flat structure may be implemented as a hernia patch, a cardiovascular patch, a neuromeninx, etc., for example. The medical device may also include a balloon (e.g., an angioplasty balloon, a urinary tract balloon, a stent deployment balloon) formed with a fine densification pattern, where the fine densification pattern helps to anchor the balloon to the patient's tissue, thereby substantially fixing the balloon in place. In some embodiments, forming the ePE substrate into an ePE article 740 may be performed before applying heat and pressure to the ePE substrate using a patterning component 720 to densify a portion of the ePE article. In some embodiments, forming the ePE substrate into an ePE article 740 may be performed after the heat and pressure step, but before shrinking the ePE substrate to a second size 730, to shrink the ePE article to the second size. In other embodiments, forming the ePE substrate into an ePE article 740 may be performed after the ePE substrate is shrunk to a second size 730 to form the ePE article in the second size. In some embodiments, forming the ePE substrate into an ePE article 740 is substantially similar to Figure 3 forming the ePE substrate into an ePE article 340 as described in Figure 4The illustrations in

[0093] Figure 8A and 8B are schematic views of ePE articles 810, 820 having a densification pattern 815, according to some embodiments. Figure 8A Shows an ePE tubular article 810, Figure 8B shows an ePE flat article 820. Both the ePE tubular article 810 and the ePE flat article 820 include a fine pattern 815. The function of this pattern 815 can be substantially similar to Figure 2A , Figure 2B and Figure 4 the fine densification pattern 235 in, and / or substantially similar to Figure 6 and the second densification pattern 655 in FIG. 8. In this embodiment, the fine pattern 815 is a densification pattern that has been shrunk to a smaller size.

[0094] In some embodiments, the ePE tubular article 810 and the ePE flat article 820 are made from a starting ePE substrate, which can be similar to the ePE substrate 210 ( Figure 2A and 2B ) or the ePE substrate 610 (FIG. 610). The starting ePE material is formed into an ePE article, which can include the ePE tubular article 810 and the ePE flat article 820. The ePE article includes a fine pattern 815. The fine pattern 815 can be formed by a selective densification patterning and shrinking process, which can be substantially similar to one of the methods described in Figure 1 , Figure 3 , Figure 5 and / or Figure 7 .

[0095] In this embodiment, the fine pattern 815 is a circular pattern or a repeating circular pattern. In other embodiments, the fine pattern 815 can have different shapes, including but not limited to square, triangular, or rectangular. In some embodiments, the fine pattern 815 is a repeating pattern. In some embodiments, the fine pattern 815 is a texture pattern. The texture pattern can include depth variations, which include local raised areas and local depressed areas.

[0096] The fine pattern 815 can impart a set of characteristics to the ePE tubular article 810 and / or the ePE flat article 820. In some embodiments, the fine pattern 815 has a texture to have antithrombogenicity. In some embodiments, the exterior of the ePE articles 810, 820 has a texture. In some embodiments, the interior of the ePE articles 810, 820 has a texture. In some embodiments, when the ePE article is the ePE tubular article 810, the inner surface of the lumen of the ePE tubular article 810 can have a texture to have antithrombogenicity. In some embodiments, the texture of the fine pattern 815 can attract cell ingrowth. In some embodiments, the texture of the fine pattern 815 can inhibit growth or ingrowth (such as thrombus growth) on the ePE articles 810, 820.

[0097] In some embodiments, the fine pattern 815 is a textured surface configured to reduce friction and surface tension, thereby enabling better adhesion. In some embodiments, the textured surface combined with the retained porosity can improve the adhesion to another surface or other devices.

[0098] In some embodiments, the fine pattern 815 is configured to promote tissue ingrowth. In some embodiments, this can be achieved by creating an increased surface area on the surface of the ePE articles 810, 820. In some embodiments, the increased surface area facilitates the formation of a textured surface or the fine pattern 815.

[0099] In some embodiments, the fine pattern 815 is configured to increase the strength of the ePE articles 810, 820 along the z-axis (e.g., along the thickness direction). This can be achieved by the selective densification and shrinkage of the ePE articles 810, 820 to produce the fine pattern 815. This can be improved by restricting the z-axis during processing. The increase in z-axis strength can also allow more than one ePE article (e.g., articles 810, 820) to be joined together by at least one of folding and bonding.

[0100] In some embodiments, the fine pattern 815 is configured to resist creep of the ePE articles 810, 820.

[0101] In some embodiments, the fine pattern 815 is configured to direct laminar flow over the surfaces of the ePE articles 810, 820. Directing laminar flow can include directing the flow of cells, body fluids, or other substances within the body. In some embodiments, this includes promoting flow to prevent blood clots. This in turn can also help improve abrasion resistance and wear resistance. The direction of the laminar flow can allow the ePE articles 810, 820 to be configured to have antibacterial properties. The laminar flow can be directed over the surfaces of the ePE articles 810, 820 in any direction. The laminar flow can also pass through the ePE articles 810, 820, such as through the lumen of the ePE tubular article 910.

[0102] In some embodiments, the fine pattern 815 is configured to facilitate tearing of the ePE articles 810, 820 along a propagation path. In some embodiments, the portion of the ePE article with the fine pattern 815 may have tear resistance. The portion of the ePE article without the fine pattern 815 may not have tear resistance, and thus when a force is applied, the portion of the ePE article without the fine pattern 815 will be torn. The portion of the ePE article without the fine pattern 815 can be selected to form a propagation path for the tear to propagate through or across the ePE article. By providing the tear-resistant fine pattern 815, the ePE articles 810, 820 can be selectively torn along the propagation path, which can be a predetermined shape. This feature can allow for more precise control of the tear location of the ePE articles 810, 820. This convenient tearing property can also be used in devices for forming fenestrations. For example, using the fine pattern 815 can cause the ePE article to selectively tear when a suture is introduced. The portion of the ePE article around the suture location can have tear resistance, so that the suture remains in place and the fenestration formed by the suture does not expand (e.g., acts as an integral grommet).

[0103] In some embodiments, the ePE articles 810, 820 are capable of expanding in the horizontal, lateral, or radial directions. The expansion ability can be achieved by shrinking the ePE substrate to form a storage length. The expansion ability can also allow for changes in the horizontal, lateral, or radial directions without adding additional mass or material to the ePE articles 810, 820.

[0104] In some embodiments, the fine pattern 815 is a regular pattern. A regular pattern can be a repeating shape or a series of repeating shapes. In other embodiments, the fine pattern 815 is an irregular pattern. An irregular pattern may not have a repeating shape or can be a random pattern.

[0105] In some embodiments, the fine pattern 815 can provide a unique tactile feel or texture. In some embodiments, the fine pattern 815 can improve moisture absorption. In some embodiments, the fine pattern 815 can provide an antibacterial surface. These features can be found in embodiments related to fabrics.

[0106] In some embodiments, the fine pattern 815 can be used to prevent device displacement. For long-term implants (e.g., stent grafts), the texture of the fine pattern 815 can increase the force required to displace the long-term implant while also providing an enhanced tissue attachment surface. In temporary implants (e.g., angioplasty or urethral balloons), the texture of the fine and dense pattern 815 may help stabilize the temporary implant while also inhibiting tissue attachment to facilitate eventual device removal.

[0107] Although specific embodiments are provided herein, it should be understood that different arrangements and material properties can be selected and processed within the spirit of the present disclosure. Additionally, the specific embodiments provide temperatures, steps, and properties that can be modified while still remaining within the spirit of the present disclosure.

[0108] The invention of the present application has been generally described above and in connection with specific embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the invention. Accordingly, the embodiments are intended to cover such modifications and variations of the invention as long as they are within the scope of the appended claims and their equivalents.

Claims

1. A method for densifying an expanded polyethylene (ePE) substrate, the method comprising: Selectively densifying a portion of the ePE substrate to form a densified portion of the ePE substrate, the ePE substrate having a first density and a first size, the densified portion of the ePE substrate having a second density greater than the first density, the densified portion of the ePE substrate having a densification pattern; And Shrinking the ePE substrate to a second size such that the densification pattern is reduced to a fine densification pattern, the second size being smaller than the first size, the fine densification pattern being smaller than the densification pattern.

2. The method according to claim 1, wherein Selectively densifying a portion of the ePE substrate is performed by embossing.

3. The method according to claim 1, wherein Selectively densifying a portion of the ePE substrate further includes applying heat and pressure to the ePE substrate.

4. The method according to claim 3, wherein, Applying heat and pressure to the ePE substrate includes contacting the ePE substrate with a component at a temperature of about 110 degrees Celsius to about 180 degrees Celsius.

5. The method according to claim 1, wherein, The method further includes forming the ePE substrate into an ePE article.

6. The method according to claim 5, wherein Forming the ePE substrate into a medical device.

7. The method according to claim 6, wherein, The medical device includes an implantable medical device.

8. The method according to claim 1, wherein, Shrinking the ePE substrate to the second size further includes applying heat to the ePE substrate.

9. The method according to claim 1, wherein, The shape of the fine densification pattern is the same as the shape of the densification pattern.

10. The method according to claim 1, wherein, The fine densification pattern is configured to promote tissue ingrowth.

11. The method according to claim 1, wherein, The fine densification pattern is configured for antithrombosis.

12. The method according to claim 1, wherein, The fine densification pattern is configured to direct laminar flow over the surface of the fine densification pattern.

13. A method for generating a pattern on an expanded polyethylene (ePE) substrate, the method comprising: Applying heat and pressure to the ePE substrate using a patterning component, the ePE substrate having a first density and a first size, the patterning component selectively densifying a first portion of the ePE substrate to a second density such that the ePE substrate has a first densification pattern in the first portion of the ePE substrate; Shrinking the ePE substrate to a second size such that the first densification pattern is reduced to a second densification pattern having a set of features, wherein the second densification pattern is smaller than the first densification pattern.

14. The method according to claim 13, wherein, The patterning component for applying heat and pressure is a mandrel.

15. The method according to claim 14, wherein, The mandrel has a texture pattern and the first densification pattern is the corresponding texture pattern.

16. The method according to claim 13, wherein, Applying heat and pressure to the ePE substrate includes contacting the ePE substrate with the patterning component at a temperature of about 110 degrees Celsius to about 180 degrees Celsius.

17. The method according to claim 13, wherein, The first densification pattern includes a first depth ratio, the second densification pattern includes a second depth ratio, and the first depth ratio and the second depth ratio are substantially the same.

18. An expanded polyethylene (ePE) article, comprising: An ePE substrate formed into an ePE article, the ePE article comprising a fine pattern formed by a selective densification patterning and shrinking process.

19. The article according to claim 18, wherein, The fine pattern has a texture for antithrombosis.

20. The article according to claim 18, wherein The fine pattern is configured to promote tissue ingrowth.

21. The article according to claim 18, wherein, The fine pattern is configured to direct laminar flow over the surface of the ePE article.

22. The article according to claim 18, wherein The fine pattern is configured to promote tearing of the ePE article along a propagation path.

23. The article according to claim 18, wherein, The fine pattern is configured to promote anti-migration properties.

24. The article according to claim 18, wherein, The fine pattern includes repeating shapes.

25. The article according to claim 18, wherein, The fine pattern is a random pattern.

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