Metallic material for medical devices, method for manufacturing a metallic material for medical devices, and medical device

Abstract

The present disclosure provides a metal material for medical devices, the metal material for medical devices having: a metal layer; and a diamond-like carbon layer containing fluorine and silicon provided on the metal layer.

Description

Technical Field

[0001] This disclosure relates to a metal material for medical devices, a method for manufacturing the metal material for medical devices, and a medical device. Background Technology

[0002] Diamond-like carbon (DLC) films are well-known as amorphous carbon films and are used in various fields due to their hard, dense, and inactive surface.

[0003] For example, techniques have been studied to impart properties such as wear resistance, corrosion resistance, and surface smoothness to the surface of substrates using inorganic materials such as metals and ceramics, or organic materials such as resins, by forming a DLC film on the surface of the substrate. Specifically, a method for improving the durability of molds or metal tools by coating the surface of a metal with DLC and then covering it with a DLC film is known. Additionally, DLC films are also used in medical devices (stents, etc.). For example, research is underway to improve the durability of metals used in medical devices by applying a DLC film to the surface.

[0004] As a specific example, Japanese Patent No. 5536168 discloses a superhydrophilic material having a DLC film with hydrophilic functional groups on the surface of a substrate, and an intermediate layer between the substrate and the DLC film to improve the adhesion between the substrate and the DLC film.

[0005] In addition, Japanese Patent No. 5661632 discloses a support comprising: a substrate layer, the surface of which is formed of a metallic material; a carbon compound layer formed of silicon carbide; a first type of diamond carbon layer containing at least silicon and free of fluorine; and a second type of diamond carbon layer (F-DLC layer) containing fluorine, wherein the atomic percentage concentration of silicon forming the first type of diamond carbon layer is 1% or more and 10% or less. Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] As mentioned above, for example, in medical devices such as stents (hereinafter referred to as medical devices), the technology of using diamond-like carbon (DLC) membranes is being researched. In the prior art, the stent described in Japanese Patent No. 5661632 suppresses the occurrence of cracks and delamination by providing a fluorine-free first DLC layer between a carbon compound layer and an F-DLC layer. Existing medical devices using DLC ​​membranes include… Figure 13As shown, a medical device having a laminated structure of F-DLC layer 32 / Si-DLC layer 36 / SiC layer 38 / substrate 34 is known.

[0008] It is common practice for medical devices to be used for extended periods after being implanted in the body.

[0009] Therefore, the medical device is required to possess the following stable properties within a living organism: the ability to continuously and stably follow the organism's movements over a long period of time, and the ability to flexibly deform in response to various stresses of varying strengths or directions while following the organism's movements. However, in the current state of the technology, medical devices have not yet achieved the ability to follow all movements of a living organism, nor the flexibility to mitigate various stresses.

[0010] This disclosure is made in view of the foregoing.

[0011] The problem to be solved by the embodiments of this disclosure is to provide a metal material for medical devices and a method for manufacturing the same, wherein the metal material for medical devices has the ability to stably follow the movement of a living organism and the ability to flexibly deform in response to various stresses during the following process.

[0012] Another embodiment of this disclosure aims to solve the problem of providing a medical device that has the ability to stably follow the movement of a living organism and the flexibility to flexibly deform in response to various stresses during the following process.

[0013] Methods for solving problems

[0014] The specific methods used to solve the problem include the following.

[0015] <1> A metal material for medical devices, wherein the metal material for medical devices has: a metal layer; and a diamond-like carbon layer, the diamond-like carbon layer being disposed on the metal layer and containing fluorine and silicon.

[0016] <2> According to the medical device metal material described in <1> above, the total concentration of fluorine contained in the diamond-like carbon layer is 7 atomic% to 10 atomic% relative to the combined concentration of carbon, fluorine and silicon.

[0017] <3> According to the above <1> or <2>, the total concentration of silicon contained in the diamond-like carbon layer is 17 atomic% to 25 atomic% relative to the total concentration of carbon, fluorine and silicon.

[0018] <4> The medical device metal material according to any one of <1> to <3> above, wherein the concentration of fluorine on the surface of the diamond-like carbon layer opposite to the side facing the metal layer in the thickness direction of the diamond-like carbon layer is greater than the concentration of fluorine on the surface facing the metal layer.

[0019] <5> According to the metal material for medical devices described in <4> above, the ratio Cf of the concentration of fluorine on the surface of the diamond-like carbon layer opposite to the side facing the metal layer to the concentration of fluorine on the surface facing the metal layer satisfies the relationship 1 < Cf ≤ 155.

[0020] <6> According to the above <4> or <5>, the concentration of fluorine contained in the diamond-like carbon layer gradually increases in the thickness direction of the diamond-like carbon layer from the side facing the metal layer toward the side opposite to the side facing the metal layer.

[0021] <7> The medical device metal material according to any one of <1> to <6> above, wherein the concentration of silicon on the surface of the diamond-like carbon layer opposite to the side facing the metal layer in the thickness direction of the diamond-like carbon layer is less than the concentration of silicon on the surface facing the metal layer.

[0022] <8> According to the metal material for medical devices described in <7> above, the ratio Cs of the silicon concentration on the surface of the diamond-like carbon layer opposite to the side facing the metal layer to the silicon concentration on the surface facing the metal layer satisfies the relationship 0.015≤Cs<1.

[0023] <9> According to the metal material for medical devices described in <7> or <8> above, the concentration of silicon contained in the diamond-like carbon layer gradually decreases in the thickness direction of the diamond-like carbon layer from the side facing the metal layer toward the side opposite to the side facing the metal layer.

[0024] <10> The metallic material for medical devices according to any one of <1> to <9> above, wherein the concentration D of the fluorine in the surface of the diamond-like carbon layer on the side opposite to the side facing the metal layer. F With respect to the concentration D of the silicon S The ratio (D) F :D S The ratio is 1:1 to 90:1.

[0025] <11> A metal material for medical devices according to any one of <1> to <10> above, wherein the diamond-like carbon layer is the outermost layer on the metal layer.

[0026] <12> A metal material for medical devices according to any one of <1> to <11> above, wherein the metal layer comprises at least one metal selected from the group consisting of titanium, nickel, cobalt, chromium, tantalum, platinum, gold and alloys thereof, and stainless steel.

[0027] <13> The metal material for medical devices described in <12> above, wherein the metal layer comprises a nickel-titanium alloy, a cobalt-chromium alloy, or stainless steel.

[0028] <14> A metal material for medical devices according to any one of <1> to <13> above, wherein the metal material for medical devices is used for a stent.

[0029] <15> The metal material for medical devices described in <14> above, wherein the stent is a stent for blood vessels throughout the body.

[0030] <16> A medical device, wherein the medical device comprises a medical device metal material as described in any one of <1> to <15> above.

[0031] <17> The medical device described in <16> above, wherein the medical device is a stent.

[0032] <18> According to the medical device described in <17> above, the stent is a stent for lower limb blood vessels.

[0033] <19> A method for manufacturing a metallic material for medical devices, wherein the method for manufacturing a metallic material for medical devices includes the following steps: using a mixed raw material containing silane compounds and fluorinated aliphatic hydrocarbons as raw material, and forming a diamond-like carbon layer containing fluorine and silicon by vapor deposition (evaporation) on a metal layer through vapor phase epitaxy (vapor growth method, hydrogen phase growth method).

[0034] Invention Effects

[0035] According to embodiments of the present invention, a metallic material for medical devices and a method for manufacturing the same are provided. This metallic material exhibits stable tracking of the movement of a living organism and flexibility to adapt to various stresses during tracking. The metallic material for medical devices disclosed herein is expected to be suitable for prolonged continuous use.

[0036] According to another embodiment of the present invention, a medical device is provided that possesses both stable tracking ability to follow the movement of a living organism and flexibility to flexibly deform in response to various stresses during tracking. The medical device of this disclosure is expected to be suitable for prolonged continuous use. Attached Figure Description

[0037] Figure 1 This is a SEM image showing the adhesion state of platelets in the test sample of Example 3, in which a single layer of DLC is formed on a NiTi alloy substrate.

[0038] Figure 2 This is a SEM image showing the adhesion state of platelets in a NiTi alloy substrate without a DLC layer.

[0039] Figure 3 This is a SEM image showing the peeling state (follow-up) of the test sample in Example 3, where a single-layer DLC layer was formed on NiTi alloy wire.

[0040] Figure 4 This is a SEM image showing the adhesion state of platelets in the test sample of Example 7, in which a single layer of DLC is formed on a SUS316L (stainless steel) substrate.

[0041] Figure 5 This is an SEM image showing the adhesion state of platelets in a stainless steel substrate without a DLC layer.

[0042] Figure 6 This is a SEM image showing the adhesion state of platelets in a test sample of Comparative Example 1, in which a multilayer DLC layer is formed on a NiTi alloy substrate.

[0043] Figure 7 This is a SEM image of the platelet adhesion state in the test sample of Comparative Example 2, which shows a multilayer DLC layer formed on a SUS316L (stainless steel) substrate.

[0044] Figure 8 This is a SEM image showing the peeling state (follow-up) of a test sample in Comparative Example 1, which shows the formation of a multilayer DLC layer on a NiTi alloy wire.

[0045] Figure 9 This is a bar chart comparing the adhesion of the DLC layer (for NiTi alloy substrate) in Examples 1 to 3 and Comparative Example 1.

[0046] Figure 10 This is a bar chart comparing the adhesion of the DLC layer (to a stainless steel substrate) in Examples 5 to 7 and Comparative Example 2.

[0047] Figure 11 This is a schematic cross-sectional view showing an example of a metallic material for medical devices according to the present disclosure.

[0048] Figure 12 This is a schematic cross-sectional view showing another example of the metallic material for medical devices disclosed herein.

[0049] Figure 13 It is a schematic cross-sectional view of existing metal materials used in medical devices. Detailed Implementation

[0050] The following provides a detailed description of the metal materials for medical devices, the manufacturing method thereof, and the medical devices disclosed herein. While the descriptions of the constituent elements herein are sometimes based on representative embodiments of this disclosure, this disclosure is not limited to such embodiments.

[0051] In this disclosure, the "~" sign indicating a range of values ​​means that the values ​​recorded before and after it are included as the lower limit and the upper limit.

[0052] In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range can be replaced by the upper or lower limit value of other numerical ranges described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of the numerical range can also be replaced by the values ​​shown in the embodiments.

[0053] In this disclosure, the term "process" includes not only independent processes, but also processes that achieve the desired effect as long as they cannot be clearly distinguished from other processes.

[0054] In this disclosure, the amount of each component in the composition refers to the total amount of the multiple substances present in the composition, unless otherwise specified, when multiple substances conforming to each component are present in the layer.

[0055] Furthermore, in this disclosure, the combination of preferred methods is a more preferred method.

[0056] Metallic Materials for Medical Devices

[0057] The metal material for medical devices disclosed herein comprises: a metal layer; and a diamond-like carbon layer (hereinafter referred to as "DLC layer") disposed on the metal layer and containing fluorine and silicon. Depending on the need, the metal material for medical devices disclosed herein may also have other layers such as an intermediate layer.

[0058] In the metal material for medical devices disclosed herein, since the DLC layer disposed on the metal layer is a diamond-like carbon layer containing fluorine (F) and silicon (Si), it has excellent stability in following the movement of a living organism, and also has the flexibility to flexibly deform in response to various stresses generated by the movement of a living organism. Therefore, it exhibits excellent stability within a living organism.

[0059] The reasons for achieving the effects of this disclosure are not yet clear, but the following inferences can be made.

[0060] In the DLC layer of the medical device metallic material disclosed herein, diamond-like carbon containing fluorine (F) and silicon (Si) is used. Diamond-like carbon is generally considered hard and has excellent surface properties, but in living organisms, it is easily regarded as a foreign body and becomes a target for attack by platelets and other organisms. In addition, the movements of living organisms are varied, and in addition to bending and tensile stresses, torsional stresses are mostly applied. In order to use continuously and stably in living organisms under such conditions for a long time, the medical device metallic material is required to have the flexibility to stably follow the movements of living organisms and to flexibly deform in response to various stresses.

[0061] Previously, it is known that F was used to impart biocompatibility to the outermost DLC layer, and Si was used to improve the adhesion of the DLC layer to the substrate.

[0062] To cope with the stresses caused by the movement of living organisms, it is important to have flexibility that allows the material to easily follow and mitigate stress. If only layers containing F or Si are used, insufficient interlayer bonding can easily occur. Even if properties corresponding to the composition are partially exhibited, it is inappropriate to assume a balance between the material's overall ability to follow the movement of living organisms and its ability to mitigate stress (flexibility) during this process. Therefore, the effect on suppressing cracks or peeling under multiple stresses is minimal.

[0063] In this disclosure, by using diamond-like carbon containing F and Si, it is possible to impart to the DLC layer a stable ability to follow the movement of a living organism, and to impart a flexibility to deform softly in response to various stresses during the following process.

[0064] Therefore, the metal material for medical devices disclosed herein can withstand long-term continuous use.

[0065] -Metal layer-

[0066] The metal material for medical devices disclosed herein has a metal layer.

[0067] The metal layer can also be in the form of a substrate suitable for forming a metallic material for medical devices (i.e., a substrate that is metallic). Alternatively, the metal layer can also be in the form of a part of a substrate suitable for forming a metallic material for medical devices (e.g., a substrate in which a material other than the desired metal (such as resin or silicone rubber) is used).

[0068] Examples of metals that can be used as the metal layer include: iron, copper, titanium, nickel, cobalt, chromium, aluminum, zinc, manganese, tantalum, tungsten, platinum, and gold. Preferably, the metal contains at least one element selected from the group consisting of titanium, nickel, cobalt, chromium, tantalum, platinum, and gold.

[0069] As a metal, it can also be an alloy of the aforementioned metals.

[0070] Alloys of the aforementioned metals include: nickel-titanium alloys, cobalt-chromium alloys, copper-aluminum-manganese alloys, copper-zinc alloys, nickel-aluminum alloys, and stainless steel. Among these alloys, nickel-titanium alloys, cobalt-chromium alloys, and stainless steel are preferred.

[0071] As for stainless steel, SUS316L is preferred, for example, in terms of corrosion resistance.

[0072] More preferably, it contains at least one metal selected from the group consisting of titanium, nickel, cobalt, chromium, tantalum, platinum, gold and their alloys, and stainless steel; even more preferably, it contains at least one metal selected from the group consisting of titanium, nickel, cobalt, chromium and their alloys, and stainless steel.

[0073] Among them, layers containing nickel-titanium alloys, cobalt-chromium alloys or stainless steel are particularly preferred, or layers formed of nickel-titanium alloys, cobalt-chromium alloys or stainless steel are preferred.

[0074] It should be noted that when the metal layer is formed of nickel-titanium alloy, cobalt-chromium alloy or stainless steel, the metal layer may contain metals other than nickel, titanium, cobalt, chromium and stainless steel, provided that it does not significantly impair the effects of the metal material for medical devices disclosed herein and the medical device.

[0075] There are no particular limitations on the thickness of the metal layer; it can be appropriately selected based on factors such as the location within the biological body where the medical device will be applied or its lifespan. When the metal layer has a flat plate shape, the thickness can be selected according to its intended use or shape. For example, when the metal layer is used as a stent, the thickness can be in the range of 50 μm to 250 μm. Similarly, when the metal layer is used as a fixation plate, the thickness can be in the range of 100 μm to 2000 μm. Furthermore, when the metal layer has shapes such as square, round, semi-circular, block, or irregular (e.g., bolts, screws, artificial hearts, artificial hip joints), the thickness can be selected according to the required shape.

[0076] The metal layer can be made by any method, or it can use commercially available products.

[0077] -Diamond-like carbon layer-

[0078] The metal material for medical devices disclosed herein has a DLC layer on a substrate.

[0079] The DLC layer in this disclosure is a diamond-like carbon layer containing fluorine (F) and silicon (Si). Due to the use of diamond-like carbon containing F and Si, it is able to exhibit stable tracking of the movement of a living organism and flexibility to deform softly in response to various stresses during tracking.

[0080] The DLC layer is a layer that can be formed by any method that contains both F and Si. DLC layers can be formed using known methods such as vapor deposition and sputtering. The DLC layer in this disclosure is preferably formed by vapor phase epitaxy.

[0081] The method for forming DLC ​​layers by vapor phase epitaxy will be described in detail in the section on manufacturing methods of metallic materials for medical devices, which will be discussed later.

[0082] -F concentration-

[0083] The total concentration of fluorine contained in the DLC layer relative to the combined concentration of carbon, fluorine, and silicon is preferably 7 atomic% to 10 atomic%, more preferably 7 atomic% to 8.5 atomic%.

[0084] The concentration of fluorine in the DLC layer can be determined by X-ray photoelectron spectroscopy (XPS). Specifically, by using an XPS device, the content of elements such as carbon (C), F, Si, and oxygen (O) as needed on the surface of the DLC layer containing F and Si is determined.

[0085] In the thickness direction of the DLC layer, the fluorine concentration (hereinafter referred to as "F concentration") on the surface opposite to the side facing the metal layer is preferably greater than the F concentration on the surface facing the metal layer. Especially when the DLC layer is the outermost layer on the metal layer, it is preferable that the F concentration on the surface opposite to the side facing the metal layer (i.e., the outermost surface) of the DLC layer is greater than the F concentration on the surface facing the metal layer, and more preferably, the F concentration on the outermost surface of the DLC layer is the largest in the thickness direction of the DLC layer.

[0086] The F concentration (C) of the surface of the DLC layer opposite to the side facing the metal layer (preferably, the outermost surface when the DLC layer is the outermost layer) F1 ), relative to the F concentration (C) on the side of the surface facing the metal layer F0 The ratio Cf (=C) F1 / C F0 Preferably, the relationship 1 < Cf ≤ 155 is satisfied. That is, preferably, the F concentration increases from the inner side of the metal layer closest to the DLC layer towards the outer side in the stacking direction of the metal layer and the DLC layer of the medical device metal material. As a result, the medical device metal material has excellent flexibility and biocompatibility.

[0087] The ratio Cf is more preferably satisfied with the relationship in Equation 1, and even more preferably satisfied with the relationship in Equation 2.

[0088] 30<Cf≤85 Equation 1

[0089] 40<Cf≤75 Equation 2

[0090] The DLC layer can also be configured such that the F concentration in the DLC layer increases stepwise along its thickness direction from the side of the DLC layer facing the metal layer towards the side opposite to the metal layer. A preferred configuration is where the F concentration in the DLC layer gradually increases from the side of the DLC layer facing the metal layer towards the side opposite to the metal layer. A stepwise increase means that the F concentration increases with a constant or arbitrary concentration difference. In the latter configuration, a preferred configuration is where, in the stacking direction of the metal layer and the DLC layer of the medical device metal material, the F concentration gradually increases from the interior of the metal layer near the DLC layer towards the direction away from the metal layer (towards the outside). This maintains the biocompatibility of the medical device metal material while exhibiting flexibility to adapt to various stresses caused by the movement of living organisms, thereby effectively suppressing cracks and peeling.

[0091] -Si concentration-

[0092] The total concentration of silicon contained in the DLC layer is preferably 17 atomic% to 25 atomic% relative to the combined concentration of carbon, fluorine and silicon, more preferably 20 atomic% to 25 atomic%.

[0093] The concentration of silicon in the DLC layer can be determined by X-ray photoelectron spectroscopy (XPS) in the same way as the concentration of F mentioned above.

[0094] In the thickness direction of the DLC layer, the silicon concentration (hereinafter referred to as "Si concentration") on the surface opposite to the side facing the metal layer is preferably less than the Si concentration on the surface facing the metal layer. Especially when the DLC layer is the outermost layer on the metal layer, it is preferable that the Si concentration on the surface facing the metal layer is greater than the Si concentration on the surface opposite to the side facing the metal layer (i.e., the outermost surface).

[0095] The Si concentration (C) on the surface of the DLC layer opposite to the side facing the metal layer. S1 ), relative to the Si concentration (C) on the side of the surface facing the metal layer S0 The ratio Cs (=C) S1 / C S0 Preferably, the Si concentration satisfies the relationship 0.015 ≤ Cs < 1. That is, preferably, the Si concentration increases towards the interior of the metal layer closer to the DLC layer in the stacking direction of the metal layer and the DLC layer of the medical device metal material. As a result, it exhibits excellent deformability in response to the movement of the organism.

[0096] Deformability refers to the property of metal materials used in medical devices to change shape due to bending, stretching, torsion, etc., caused by the movement of living organisms.

[0097] The ratio Cs is more preferably satisfied with the relationship in Equation 3, and even more preferably satisfied with the relationship in Equation 4.

[0098] 0.3≤Cs<1 Equation 3

[0099] 0.3≤Cs<0.8 Equation 4

[0100] The DLC layer can also be configured such that the Si concentration in the DLC layer decreases in a stepwise manner along the thickness direction of the DLC layer from the side of the DLC layer facing the metal layer toward the side opposite to the metal layer. A preferred configuration is where the Si concentration in the DLC layer gradually decreases from the side of the DLC layer facing the metal layer toward the side opposite to the metal layer. A stepwise decrease means that the F concentration decreases with a constant or arbitrary concentration difference. In the latter configuration, a preferred configuration is where, in the stacking direction of the metal layer and the DLC layer of the medical device metal material, the Si concentration gradually increases toward the interior of the metal layer closer to the DLC layer. This results in excellent deformation properties that allow the medical device metal material to deform under bending, stretching, torsional, and other forces applied by the movement of a living organism, thereby effectively suppressing cracks and peeling.

[0101] The F concentration D on the surface of the DLC layer, opposite to the side facing the metal layer. F With Si concentration D S The ratio (D) F :D S The ratio is preferably 1:1 to 90:1, more preferably 1:1 to 80:1, and even more preferably 1:1 to 50:1.

[0102] Due to the ratio of the DLC layer on the surface opposite to the side facing the metal layer (D F :D S Within the aforementioned range, the composition of the DLC layer, which is furthest from the metal layer, exhibits a higher content of F than Si within a certain range. This allows for more flexible deformation under various stresses while following the movement of a living organism. This effect is even more pronounced when the DLC layer is the outermost layer of a metallic material used in medical devices.

[0103] As mentioned above, since the DLC layer can deform more flexibly in response to various stresses while following the movement of the organism, it is preferable to place the DLC layer as the outermost layer on the metal layer.

[0104] From the viewpoint of medical device use, the thickness of the DLC in this disclosure is preferably thin, for example, preferably in the range of 10 nm or more and less than 1000 nm, more preferably in the range of 100 nm to 500 nm, and even more preferably in the range of 150 nm to 250 nm.

[0105] The metal material for medical devices disclosed herein can be in any form as long as it has a DLC layer containing F and Si on a metal layer. Specifically, the metal material for medical devices can also have the following layered structure.

[0106] (1) DLC layer / metal layer containing F and Si

[0107] (2) DLC layer containing F and Si / DLC layer without F and Si / Metal layer

[0108] (3) DLC layer containing F and Si / DLC layer containing Si / Metal layer

[0109] (4) DLC layer containing F and Si / intermediate layer other than DLC layer / metal layer

[0110] From the perspective of softness and stability in living organisms, the form in which the DLC layer is in contact with the metal layer and the DLC layer is the outermost layer of the metal material for medical devices is preferred, and the form described above (1) is particularly preferred.

[0111] Figure 11 This illustrates an example of a metallic material for medical devices disclosed herein.

[0112] Figure 11 The medical device metal material 10 shown is an example of (1) above, in which a DLC layer 12 containing F and Si is stacked on the metal layer 14. If it is the configuration described in (2) above, the stacked structure is as follows: Figure 11 A DLC layer without F and Si is disposed between the DLC layer 12 and the metal layer 14.

[0113] Figure 12 This represents another example of the metallic materials for medical devices disclosed herein.

[0114] Figure 12 The medical device metal material 20 shown is another example of (1) above. A DLC layer 22 is stacked on the metal layer 24, wherein the DLC layer 22 contains F and Si, and the F concentration gradually increases from the side of the DLC layer facing the metal layer 24 (i.e., the side closer to the metal layer) towards the side opposite to the side facing the metal layer (i.e., the side farther from the metal layer) in the thickness direction of the DLC layer. That is, in the thickness direction of the DLC layer, the F concentration on the surface of the side opposite to the side closer to the metal layer is greater than the F concentration on the surface of the side closer to the metal layer 24. In this configuration, the Si concentration gradually decreases in the thickness direction of the DLC layer from the side of the DLC layer facing the metal layer 24 towards the side opposite to the side facing the metal layer 24.

[0115] It should be noted that in the above-mentioned stacked structure, "DLC layer without F and Si" means that if F and Si are not present, other atoms can also be contained in the DLC layer. "Without F and Si" means that the content of F and Si is less than 1.0 atom% relative to the total number of carbon, fluorine, and silicon atoms in the DLC layer.

[0116] "DLC layer containing Si" refers to a DLC layer that contains Si, and if it does not contain F, it may contain other atoms besides F and Si. "F-free" means that the F content is less than 1.0 atomic% relative to the total number of carbon, fluorine, and silicon atoms in the DLC layer.

[0117] "Intermediate layers other than DLC layers" can be, for example, layers made of silicon carbide (SiC), titanium carbide (TiC), chromium carbide (Cr3C2), titanium silicon carbide (Ti3SiC2), etc.

[0118] There are no particular restrictions on the use of the metallic materials for medical devices disclosed herein.

[0119] Applications of metallic materials for medical devices include, for example, stents, catheter instruments, endoscopic instruments, or fixing instruments such as bolts and screws.

[0120] The aforementioned stent is suitable as a vascular stent. A stent is a medical device that expands a tubular portion of the human body (e.g., a blood vessel) from within its lumen. The stent made of metallic material used in the medical device disclosed herein is a stent for the blood vessels throughout the human body (a stent for the blood vessels of the whole body), suitable for blood vessels such as cerebral vessels, pulmonary vessels, cardiac vessels (e.g., coronary arteries), trunk vessels (e.g., superior mesenteric artery, common hepatic artery), and lower limb vessels (e.g., lower limb veins).

[0121] In terms of more effective performance, the metal material for medical devices disclosed herein is suitable for use in blood vessels with greater movements such as bending, stretching and twisting, and is therefore more suitable for stents used in cardiac or lower limb blood vessels.

[0122] <Manufacturing Methods for Metallic Materials for Medical Devices>

[0123] The method for manufacturing metallic materials for medical devices disclosed herein includes the following steps (hereinafter referred to as the DLC layer formation step): using a mixture of silane compounds and fluorinated aliphatic hydrocarbons as raw materials, a diamond-like carbon layer (DLC layer) containing fluorine and silicon is formed on the metallic layer by vapor phase epitaxy. The method for manufacturing metallic materials for medical devices disclosed herein may also include other steps as needed.

[0124] -DLC layer formation process-

[0125] The DLC layer formation process in this disclosure uses a mixture of raw materials containing silane compounds and fluorinated aliphatic hydrocarbons to form a diamond-like carbon layer containing fluorine and silicon by vapor deposition on a metal layer via vapor phase epitaxy.

[0126] Vapor phase epitaxy includes chemical vapor deposition (CVD) and physical vapor deposition (PVD).

[0127] Examples of CVD methods include plasma-enhanced chemical vapor deposition (PE-CVD) and thermochemical vapor deposition. Thin films containing F, Si, and C can be formed using PE-CVD.

[0128] PE-CVD is a type of chemical vapor deposition (CVD) method that uses gases in the raw materials. It involves introducing a raw material gas into a vacuum chamber to generate plasma, which triggers a chemical reaction to deposit a film. CVD is a general term for methods that utilize chemical reactions to deposit films on a substrate.

[0129] As an energy source to initiate chemical reactions, heat, plasma, lasers, etc., can be used. In the CVD method, gas is used as the feedstock. Therefore, by selecting the feedstock gas, the quality of the film that can be formed can be freely changed, and various elements can be added as needed.

[0130] In this disclosure, a DLC layer can be appropriately formed by CVD. Therefore, film formation conditions (e.g., various parameters) can be controlled as needed to suit the formation of a DLC layer where the F and Si concentrations vary along the thickness direction of the DLC layer.

[0131] PE-CVD (Polyethylene-Liquid Crystallization) is a process that deposits a film by introducing hydrocarbon gas or a gas containing the desired added element into a vacuum chamber, generating plasma, and causing a chemical reaction. For generating the plasma, AC power such as direct current, high-frequency power, or microwave power is preferred. PE-CVD can utilize plasma to react highly activated chemical species, allowing the reaction to occur at low temperatures.

[0132] The DLC layer disclosed herein can be formed using an inductively coupled plasma-chemical vapor deposition (ICP-CVD) apparatus that utilizes a high frequency. For example, the YH-100NX manufactured by Onward Technology Co., Ltd. can be used as the ICP-CVD apparatus.

[0133] In an ICP-CVD apparatus, plasma is generated between ring electrodes through high-frequency discharge. By applying a bias voltage to a fixture on which a substrate is mounted, ionized or excited chemical species are adsorbed and deposited to form a film. The film formation conditions can be controlled by parameters such as processing time, high-frequency output, bias voltage, feed gas flow rate, high-frequency pulse amplitude, bias voltage pulse amplitude, high-frequency voltage at plasma ignition, bias voltage, and feed gas flow rate.

[0134] Examples of PVD methods include plasma ion implantation, vacuum vapor deposition, and sputtering.

[0135] As a raw material, a mixture of silane compounds and fluorinated aliphatic hydrocarbons is used.

[0136] As silane compounds, organosilicon compounds containing carbon are preferred. Examples of organosilicon compounds include those represented by the following formula S.

[0137] SiR x H 4-x Formula S

[0138] In formula S, R represents an alkyl group with 1 to 4 carbon atoms, and x represents an integer from 1 to 4.

[0139] Examples of compounds represented by the formula S include: tetramethylsilane, tetraethylsilane, trimethylsilane, diethylsilane, methyldiethylsilane, diethyldimethylsilane, etc.

[0140] As fluorinated aliphatic hydrocarbons, fluorinated aliphatic hydrocarbons with 1 to 4 carbon atoms are preferred, and perfluorocarbons with 1 to 4 carbon atoms are more preferred. Examples of fluorinated aliphatic hydrocarbons include tetrafluoromethane (CF4), hexafluoroethane (C2F6), octafluoropropane, and perfluorobutane (C4F6). 10 )wait.

[0141] Hydrocarbons can also be used as raw materials.

[0142] When using the CVD method, saturated hydrocarbons (e.g., methane (CH4), ethane (C2H6) etc.) and unsaturated hydrocarbons (e.g., acetylene (C2H2), benzene (C6H6) etc.) can be used as hydrocarbons.

[0143] When using the PVD method, solid carbon can be used as hydrocarbon.

[0144] In the DLC layer formation process, a silane compound is vaporized, and the vaporized silane compound and fluorinated aliphatic hydrocarbons (unsaturated hydrocarbons may also be added) are introduced into a chamber for film formation. At this time, it is preferable to control the partial pressure of the silane compound and the fluorinated aliphatic hydrocarbons to allow for gradual changes in their concentrations. The mixed feedstock of silane compound and fluorinated aliphatic hydrocarbons can be mixed in any controlled ratio to form the DLC layer of this disclosure. For example, it can be carried out in the following manner.

[0145] That is, firstly, silane compounds and fluorinated aliphatic hydrocarbons are supplied to the surface of the metal layer with a mixing ratio of silane compounds greater than or equal to that of fluorinated aliphatic hydrocarbons, and adsorption and deposition occur. Initially, no mixed material may be used, and only silane compounds may be used. Then, the mixing ratio of silane compounds is reduced (preferably gradually reduced), and the mixing ratio of fluorinated aliphatic hydrocarbons is increased (preferably gradually increased), while adsorption and deposition continue, thereby continuously forming a film.

[0146] By forming a film in this manner, a DLC layer with a compositional distribution in which the amount of F increases (preferably gradually increases) and the amount of Si decreases (preferably gradually decreases) in the deposition direction (thickness direction of the layer formed) from the metal layer side.

[0147] -Other processes-

[0148] In the method for manufacturing metallic materials for medical devices disclosed herein, when a substrate is used as the metallic layer, an etching step on the substrate may be included as an additional step. Etching further improves the adhesion between the substrate and the DLC layer.

[0149] As an etching method, dry etching methods such as ion beam etching and plasma etching can be used.

[0150] Gases used in etching include: rare gases (such as helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), etc.), halogen gases containing halogen atoms (such as CCl4, CClF3, AlF3, AlCl3, etc.), O2, N2, CO, CO2, etc.

[0151] A gas can be used alone or as a mixture of two or more gases.

[0152] The etching process is preferably a plasma etching process on the surface of the substrate.

[0153] In the manufacturing method of the metal material for medical devices disclosed herein, as another step, a step of further forming a coating layer containing a drug on the DLC layer may also be included.

[0154] A drug release layer containing the target drug (e.g., a polymer layer containing the drug and a polymer) can be provided on at least a portion of the DLC layer. Thus, as described above, drug release functionality can be provided while maintaining excellent conformability and flexibility.

[0155] The choice of drug depends on the purpose, such as causing the death of target cells.

[0156] <Medical Devices>

[0157] The medical device disclosed herein is a medical device having the metallic material for medical devices described above.

[0158] Examples of medical devices disclosed herein include: stents, catheter instruments, endoscopic instruments, or fixation devices such as bolts and screws, artificial hearts, artificial hip joints, and fixation plates. The medical devices disclosed herein are suitable as stents, suitable as stents for use in blood vessels throughout the human body, and more suitable as stents for use in blood vessels of the lower limbs, brain, lungs, heart, and trunk.

[0159] The lower limbs refer to the entire leg, from the hip joint to the toes, including the three major joints of the hip, knee, and ankle, as well as the toes.

[0160]

Example

[0161] The present invention will be described in more detail below through embodiments, but the present invention is not limited to the following embodiments as long as it does not depart from its spirit.

[0162] [Example 1]

[0163] -1. Preparation of the substrate (metal layer)-

[0164] As substrates, NiTi alloy substrates and silicon (Si) substrates were prepared for chemical composition analysis and adhesion evaluation. Additionally, a NiTi alloy substrate was prepared for blood compatibility evaluation. Furthermore, NiTi wires were prepared to evaluate the conformability of the substrate, which was assumed to be a scaffold. The substrate thickness was 380 μm, and the wire diameter was 150 μm.

[0165] -2. Preparation of raw material gases-

[0166] The following compounds were prepared as raw materials for the modulating feed gas.

[0167] • Silane compounds: Tetramethylsilane (Si(CH3)4)

[0168] Fluorinated aliphatic hydrocarbons: perfluoropropane (C3F8)

[0169] -3. Formation of DLC Layers-

[0170] A DLC layer containing F and Si is formed on a substrate or wire according to the steps shown below.

[0171] (1) Etching process

[0172] First, under the following conditions, a plasma etching-based surface treatment is performed on the surface of each substrate to improve the adhesion of the substrate surface.

[0173] <Etching Conditions>

[0174] • Etching equipment: YH-100NX (developed by Onward Technology Co., Ltd.)

[0175] • Etching gas: Argon (Ar) gas

[0176] • Etching time: 10–1000 seconds

[0177] • Gas flow rate: 10 mL / min

[0178] (2) Film formation

[0179] An inductively coupled plasma-chemical vapor deposition (ICP-CVD) apparatus YH-100NX, manufactured by Onward Technology Co., Ltd., was prepared, and various substrates were sequentially arranged in the chamber. Then, vaporized tetramethylsilane (TMS; silane compound) and perfluoropropane (OFP / alias: octafluoropropane; fluorinated aliphatic hydrocarbon) were introduced to form films on the surface of each substrate.

[0180] Film formation is achieved by controlling the partial pressure PSi of TMS and the partial pressure PF of OFP within the inlet chamber. Specifically, as shown in Table 1, TMS is first introduced at a flow rate of 6 sccm (PSi: 0.22 Pa), and while maintaining the flow rate of TMS, the flow rate of OFP is gradually increased until it reaches 50 sccm (PF: 0.53 Pa).

[0181] As described above, a medical material (metallic material for medical devices) is fabricated by forming a DLC layer with a thickness of 200 nm on a substrate or wire. The elemental composition of carbon, fluorine, and silicon in the DLC layer is determined by the following method.

[0182] -4. Measurement and Evaluation-

[0183] The following measurements and evaluations were performed on the DLC layers formed on the substrate or wire.

[0184] (1. F concentration and Si concentration)

[0185] The F and Si concentrations were determined by chemical composition analysis of test samples with DLC layers formed on Si or NiTi alloy substrates using the following methods. The results are shown in Tables 2 and 3.

[0186] Using an XPS apparatus (JPS-9010TR manufactured by Nippon Electronics Corporation), the elemental content (content of C, F, Si, and O) was determined based on the spectra measured on the outermost surface of the DLC layer, the surface in contact with the substrate of the DLC layer, and along the thickness direction of the DLC layer. Furthermore, the outermost surface of the DLC layer is the surface of the DLC layer on the side opposite to the side in contact with the substrate.

[0187] The specific steps are as follows.

[0188] a) The X-ray source used was MgKα, and the X-ray generation conditions were 10kV and 10mA. The C, F, Si and O of each surface of the untreated DLC layer formed on each substrate were analyzed.

[0189] b) Next, the surfaces of the DLC layer are etched for 10 seconds using an Ar gas cluster ion beam (GCIB).

[0190] c) Using the same method as a) above, the C, F, Si and O inside the DLC layer that was etched in b) above were analyzed.

[0191] d) Based on the measured spectra, determine the elemental content of the surface and interior of the DLC layer. The elemental content is calculated using the correlation sensitivity coefficient method based on the spectral area of ​​each element obtained from the measurements.

[0192] Furthermore, by etching the DLC layer and measuring its interior, the surface of the DLC layer in contact with the substrate and the elemental content in the thickness direction of the DLC layer can be determined. By etching the DLC layer at predetermined intervals in the thickness direction, the elemental distribution in the plane parallel to the outermost surface in the thickness direction within the layer is measured. The amounts of carbon, fluorine, and silicon in the DLC layer are integrated from the outermost surface towards the thickness direction to obtain the elemental content in the thickness direction of the DLC layer.

[0193] Furthermore, in the determination of elemental distribution on the outermost surface and in the thickness direction of the DLC layer, a DLC layer formed using a silicon (Si) substrate was used. In the determination of the surface of the DLC layer in contact with the substrate, a DLC layer formed using a NiTi alloy substrate was used.

[0194] (2. Fit)

[0195] The adhesion of the DLC layer to the NiTi alloy substrate was evaluated using a scratch test. Specifically, a nano-scratch tester (Rhesca CSR5000) was used to determine the critical peel load of the DLC layer five times, and the average value of the five tests was calculated as the index for evaluating adhesion. The evaluation results are shown in Table 4 and... Figure 9 As shown.

[0196] <Steps>

[0197] (1) Use the top diameter A diamond indenter is used to scan the surface of a DLC layer formed on a NiTi alloy substrate under the following conditions.

[0198] <Experimental Conditions>

[0199] Maximum load: 100mN

[0200] • Load application rate: 1.67 mN / s

[0201] • Scratch length: 600μm

[0202] Number of trials: 5

[0203] (2) Measure the peeling start point of the DLC layer generated during the scanning and calculate the critical peeling load.

[0204] (3) Based on the results of the stripping critical load, the following evaluation criteria shall be used for evaluation.

[0205] <Evaluation Criteria>

[0206] A: It exhibits extremely excellent fit.

[0207] B: Shows a level of tightness that does not affect actual use.

[0208] C: Poor fit.

[0209] (3. Followership)

[0210] The following evaluation method was used: electron microscopy observation, to assess the following effect of the DLC layer on the deformation of the NiTi wire. Specifically, the test sample was prepared using NiTi wire, the most deformable material, and bent at a 120° angle. The bent sample was then observed using scanning electron microscopy (SEM), and the following evaluation criteria were used to assess the following effect of the DLC layer on the deformation caused by bending. The evaluation results are shown in Table 4.

[0211] <Evaluation Criteria>

[0212] A: It is highly flexible and exhibits excellent responsiveness.

[0213] B: The flexibility is slightly insufficient. No peeling of the DLC layer was observed, but cracks were found in the DLC layer.

[0214] C: Lack of flexibility; peeling areas were observed on the DLC layer.

[0215] (4. Blood compatibility)

[0216] Platelet adhesion tests are performed to evaluate the antithrombotic properties of samples by attaching platelets to a NiTi alloy substrate or a substrate with a DLC layer formed on a NiTi alloy substrate, thereby assessing blood compatibility. The primary cause of thrombosis in intravascular biomaterials is blood coagulation due to the surface properties of materials known as intrinsic clotting factors; therefore, it can be said that the lower the amount of platelets attached, the higher the blood compatibility.

[0217] The experiments were conducted using a NiTi alloy substrate and a substrate with a DLC layer, following the steps outlined below. The results are shown in Table 4.

[0218] <Steps>

[0219] (1) Platelet-rich plasma (PRP) separated from the blood of healthy adults was added to a NiTi alloy substrate or a substrate with a DLC layer formed on a NiTi alloy substrate and fused together. The substrate was then incubated in a CO2 incubator at 37°C, with a CO2 partial pressure ratio of 5% in the air, for 60 min.

[0220] Platelet-rich plasma (PRP) is a blood solution with a high platelet concentration that is separated from the blood.

[0221] (2) After incubation, carefully remove the blood from the NiTi alloy substrate or sample and wash it with physiological saline.

[0222] (3) After dehydration, the platelets attached to the surface of the DLC layer of the NiTi alloy substrate or the substrate with DLC layer are fixed and then observed using a differential interference microscope, which is a type of optical microscope.

[0223] (4) Evaluate the platelet attachment status observed in the microscopic photographs according to the following evaluation criteria.

[0224] <Evaluation Criteria>

[0225] A: Very few platelets adhere to the platelet.

[0226] B: Platelet attachment is visible.

[0227] C: Platelet attachment is clearly visible.

[0228] [Example 2]

[0229] In Example 1, as shown in Table 1, in addition to controlling the partial pressure P of the TMS introduced into the chamber... Si The voltage divider P of OFP FIn addition to varying the fluorine and silicon content ratio along the thickness direction of the DLC layer to form a film, the DLC layer was also formed in the same manner as in Example 1, and further measurements and evaluations were performed. Specifically, firstly, 6 sccm (P Si The film was formed by introducing a flow rate of 0.22 Pa (PF: 0.53 Pa) into the TMS, gradually decreasing the TMS flow rate while gradually increasing the OFP until a flow rate of 50 sccm (PF: 0.53 Pa) was reached. The measurement and evaluation results are shown in Tables 2 and 3, and... Figure 9 As shown.

[0230] [Example 3]

[0231] In Example 1, as shown in Table 1, in addition to controlling the partial pressure P of the TMS introduced into the chamber... si The voltage divider P of OFP F The partial pressure P of acetylene C In addition to forming a film by varying the ratio of carbon, fluorine, and silicon along the thickness direction of the DLC layer, the DLC layer was also formed in the same manner as in Example 1, and further measurements and evaluations were performed.

[0232] Specifically, firstly, 6sccm(P) Si A flow rate of 0.22 Pa is introduced into the TMS, and the flow rate of the TMS is gradually reduced while the OFP is gradually increased until it reaches 50 sccm (Pa). F The flow rate was increased to 0.53 Pa, and the acetylene flow rate was gradually increased until it reached 3 sccm (P). F Film formation is achieved using a flow rate of 0.11 Pa.

[0233] The measurement and evaluation results are shown in Tables 2 and 3. Figure 1 (In contrast, Figure 2 ), Figure 3 and Figure 9 As shown. In Figure 9 In the image, the white areas visible within the field of view are the regions where peeling has occurred.

[0234] [Example 4]

[0235] In Example 1, except that the substrate type was changed from NiTi alloy to CoCr alloy, a DLC layer was formed in the same manner as in Example 1, and further measurements and evaluations were performed. The measurement and evaluation results are shown in Table 4.

[0236] [Examples 5 to 7]

[0237] In each of Examples 1 to 3, except that the substrate type was changed from NiTi alloy to SUS316L (stainless steel), the DLC layer was formed in the same manner as in Example 1, and further measurements and evaluations were performed. The measurement and evaluation results are shown in Table 4. Figure 4 (In contrast, Figure 5 )and Figure 10 As shown.

[0238] [Comparative Example 1]

[0239] A NiTi alloy substrate was prepared as the substrate in the same manner as in Example 1. After argon bombardment of the substrate surface for approximately 10 minutes, a SiC layer with a thickness of approximately 100 nm was formed using tetramethylsilane (TMS) as the feed gas. Next, a Si-DLC layer with a thickness of approximately 100 nm was formed on the surface of the SiC layer as the first DLC layer using tetramethylsilane (TMS) and acetylene (C2H2) as feed gases. Subsequently, a fluorinated DLC layer (F-DLC layer) with a thickness of approximately 200 nm was formed on the surface of the Si-DLC layer using perfluoropropane (C3F8) and acetylene (C2H2) as feed gases as the second DLC layer. Furthermore, the gas flow rates and reaction times were appropriately adjusted during the formation of the SiC layer, Si-DLC layer, and F-DLC layer to obtain the aforementioned thicknesses of each layer.

[0240] As mentioned above, such as Figure 13 As shown, a scaffold with a laminated structure of F-DLC layer / Si-DLC layer / SiC layer / substrate was fabricated. The fabricated scaffold was measured and evaluated in the same manner as in Example 1. The measurement and evaluation results are shown in Tables 3 and 4. Figure 6 , Figure 8 and Figure 9 As shown. In Figure 8 In the image, the white areas visible within the field of view are the regions where peeling has occurred.

[0241] [Comparative Example 2]

[0242] Except that the substrate type in Comparative Example 1 was changed from NiTi alloy to SUS316L (stainless steel), the measurements and evaluations were performed in the same manner as in Comparative Example 1. The measurement results are as follows: Figure 7 and Figure 10 As shown.

[0243] [Table 1]

[0244]

[0245] [Table 2]

[0246]

[0247]

[0248] [Table 3]

[0249]

[0250] [Table 4]

[0251]

[0252] As shown in Table 4, in the embodiment where the concentrations of fluorine (F) and silicon (Si) in a single-layer DLC layer are gradually varied along the thickness direction, good results were obtained in terms of adhesion, conformability and blood compatibility compared to Comparative Example 1, which has a multilayer structure containing F and Si in different layers.

[0253] from Figure 1 (Example 3) and Figure 6 As can be seen from the comparison (Comparative Example 1), in the test sample (medical device metal material) of Example 3 with a single-layer DLC layer on a NiTi alloy substrate, the number of platelets attached was significantly reduced compared to Comparative Example 1, where the DLC layer was a multi-layered structure. Furthermore, as a reference example, in a NiTi alloy substrate without a DLC layer, such as... Figure 2 As shown, the degree of platelet adhesion is quite obvious. This is evident from... Figure 4 (Example 7) and Figure 7 The comparison in (Comparative Example 2) also shows that the same results were obtained between Example 7, where a SUS316L (stainless steel) substrate was used instead of a NiTi alloy substrate, and Comparative Example 2. Furthermore, through comparison... Figure 4 (Example 7) and Figure 5 (The reference example without a DLC layer) can also be clearly seen. That is, similar to the case using a NiTi alloy substrate, in the case of a single DLC layer on a stainless steel substrate (the test sample of Example 7 (metal material for medical devices)), the number of platelets attached is significantly reduced compared to the case using a stainless steel substrate without a DLC layer.

[0254] In addition, from Figure 3 (Example 3) and Figure 8 (Comparison Example 1) shows that the test sample of Example 3 (medical device metal material) which uses a NiTi alloy wire scaffold and has a single-layer DLC layer on the NiTi alloy wire, can suppress the peeling of the DLC layer and has been confirmed to have excellent followability compared to Comparison Example 1, which has a multi-layered structure of DLC layer.

[0255] Regarding the adhesion of the DLC layer, see Table 4, and Figure 9 and Figure 10 As shown, in Examples 1 to 3 and Examples 5 to 7, in which the concentrations of fluorine (F) and silicon (Si) in a single-layer DLC layer are gradually varied along the thickness direction, the results are superior to those of Comparative Example 1 or Comparative Example 2, which contain F and Si in different layers.

Claims

1. A metallic material for medical devices, wherein, The metallic material used in the medical device has the following characteristics: Metal layer; and A diamond-like carbon layer is disposed on the metal layer and contains fluorine and silicon in a single layer; wherein the composition of the diamond-like carbon layer at the surface furthest from the metal layer contains more fluorine than silicon. The concentration of fluorine on the surface of the diamond-like carbon layer opposite to the side facing the metal layer in the thickness direction is greater than the concentration of fluorine on the surface facing the metal layer. The silicon concentration on the surface of the diamond-like carbon layer opposite to the side facing the metal layer in the thickness direction of the diamond-like carbon layer is less than the silicon concentration on the surface facing the metal layer. The concentration D of fluorine in the surface of the diamond-like carbon layer on the side opposite to the side facing the metal layer. F With respect to the concentration D of silicon S The ratio (D) F :D S The ratio is 1:1 to 90:

1.

2. The metallic material for medical devices according to claim 1, wherein, The total concentration of fluorine contained in the diamond-like carbon layer is 7 atomic% to 10 atomic% relative to the combined concentration of carbon, fluorine and silicon.

3. The metallic material for medical devices according to claim 1, wherein, The total concentration of silicon contained in the diamond-like carbon layer is 17 atomic% to 25 atomic% relative to the combined concentration of carbon, fluorine and silicon.

4. The metallic material for medical devices according to claim 1, wherein, The ratio Cf of the concentration of fluorine on the surface of the diamond-like carbon layer opposite to the side facing the metal layer, relative to the concentration of fluorine on the surface facing the metal layer, satisfies the relationship 1 < Cf ≤ 155.

5. The metallic material for medical devices according to claim 1, wherein, The concentration of fluorine contained in the diamond-like carbon layer gradually increases in the thickness direction of the diamond-like carbon layer from the side facing the metal layer toward the side opposite to the side facing the metal layer.

6. The metallic material for medical devices according to claim 1, wherein, The ratio Cs of the silicon concentration on the surface of the diamond-like carbon layer opposite to the side facing the metal layer, relative to the silicon concentration on the surface facing the metal layer, satisfies the relationship 0.015 ≤ Cs < 1.

7. The metallic material for medical devices according to claim 1, wherein, The concentration of silicon in the diamond-like carbon layer gradually decreases in the thickness direction of the diamond-like carbon layer from the side facing the metal layer toward the side opposite to the side facing the metal layer.

8. The metallic material for medical devices according to claim 1, wherein, The metal layer has the diamond-like carbon layer as the outermost layer.

9. The metallic material for medical devices according to claim 1, wherein, The metal layer comprises at least one metal selected from the group consisting of titanium, nickel, cobalt, chromium, tantalum, platinum, gold and their alloys, and stainless steel.

10. The metallic material for medical devices according to claim 9, wherein, The metal layer comprises a nickel-titanium alloy, a cobalt-chromium alloy, or stainless steel.

11. The metallic material for medical devices according to claim 1, wherein, The metal material used in the medical device is used for the stent.

12. The metallic material for medical devices according to claim 11, wherein, The stent is a stent used for blood vessels throughout the body.

13. A medical device, wherein, The medical device comprises a metallic material for medical devices as described in any one of claims 1 to 12.

14. The medical device according to claim 13, wherein, The medical device in question is a stent.

15. The medical device according to claim 14, wherein, The stent in question is a stent used for lower limb blood vessels.

16. A method for manufacturing a metallic material for medical devices according to any one of claims 1 to 12, wherein, The manufacturing method of the metal material for medical devices includes the following steps: using a mixture of silane compounds and fluorinated aliphatic hydrocarbons as raw materials, a diamond-like carbon layer containing fluorine and silicon is formed by vapor deposition on the metal layer through vapor phase epitaxy.

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