Plasma electrodes and plasma devices for wound treatment.

Abstract

The present invention provides a floating-type plasma electrode pad in which, by a voltage applied to a plasma electrode which is adjacent to the skin of a human body, plasma is generated between the skin of the human body and the plasma electrode, wherein the skin of the human body acts as a ground electrode, the plasma electrode pad comprising: a plasma electrode comprising a conductive metal thin film; a polymer-based flexible dielectric thin film which is laminated on the plasma electrode and spaced apart from the skin of the human body by a predetermined distance to form micro-discharging in the separation space; and a spacer which is laminated on the dielectric thin film and separates the dielectric thin film from the skin of the human body by a predetermined distance, wherein the spacer is provided as a fabric material that is woven such that fabric bundles form multilayers.

Description

Plasma electrode pads for wound treatment and plasma treatment devices

[0001] The present invention relates to a plasma treatment device that can be used for the purpose of medical treatment, and in particular to a plasma electrode pad that is attached to the skin like a pad and is capable of generating plasma to help sterilize the affected area and regenerate tissue.

[0002] Recently, atmospheric pressure plasma is being applied not only to engineering but also to convergence technologies in bio research and medical devices. In electrode modules that generate plasma, a discharge forms in the space between the electrodes when a high voltage is applied to both electrodes, leading to the ionization of reactive gases and the generation of plasma. The plasma thus formed contains various functional ions. It has been reported that reactive species generated within the plasma possess significant effects when applied to various human treatments, such as sterilization, wound healing, hemostasis, and apoptosis. Among these reactive species, ROS (Reactive Oxygen Species) are effective for sterilization, while RNS (Reactive Nitrogen Species) are effective for maintaining cellular homeostasis. Conventionally, while plasma technology has been applied to medical devices in some cosmetic fields, such as teeth whitening, it is still difficult to find commercially available medical plasma devices that perform therapeutic functions—such as sterilization, cleaning, and cell regeneration—by directly acting on the human body.

[0003] When considering plasma electrode modules for use as medical devices, the following technical challenges must be addressed. Generally, over 90% of research has focused on small-scale Direct Barrier Discharge (DBD) or corona jet type plasmas with low discharge voltages. Conventional plasma modules consume large amounts of gases, such as helium or argon, supplied for discharge, requiring additional gas supply facilities. Consequently, system simplification must be developed to integrate plasma into various technological fields.

[0004] Meanwhile, research on atmospheric pressure plasma using air instead of discharge gas has mostly focused on dielectric barrier discharge (DBD) structures or torch-type electrode structures. Conventional electrode structures have small electrode spacing or small plasma processing cross-sectional areas, which presents a problem in that electrodes must be designed to be large to induce large-area discharge while increasing power efficiency.

[0005] As a related patent document, Korean Registered Patent No. 10-1292268 (hereinafter abbreviated as "prior patent") discloses a parallel-driven microplasma wound treatment device. The aforementioned prior patent exemplifies a plasma module that considers various surface areas and portability in relation to the application issues of the medical plasma mentioned above. As with the prior patent, plasma electrode modules for direct application to the human body generally adopt the Direct DBD model. The Direct DBD model has a structure in which an electrode to which power is applied and a ground electrode are configured together in the plasma electrode module. To explain using the prior patent as an example, the first electrode (1a) and the second electrode (1b) correspond to this, and plasma is generated in the space between these two electrodes.

[0006] The Direct DBD model radiates plasma generated between electrodes onto the skin. Considering this, the Direct DBD model may be suitable for implementation as a handpiece. However, the Direct DBD model has structural disadvantages when attempting to implement the electrode module in the form of a pad attached to the skin. In the Direct DBD model, plasma is not directly irradiated onto the skin; instead, plasma generated between the electrodes is irradiated indirectly. Consequently, the Direct DBD model may require relatively high power to generate plasma capable of producing a therapeutic effect. In this case, medical devices intended for therapeutic purposes face the problem of being unable to simultaneously satisfy various approval requirements regarding safety.

[0007] Plasma devices inevitably generate ozone during the ionization process of plasma generation. Ozone is one of the most toxic substances when inhaled into the human respiratory system. The stronger the plasma is generated, the higher the amount of ozone produced. Therefore, it is desirable for medical plasma electrode modules to be designed so that plasma is formed directly on the skin, allowing for therapeutic efficiency with minimal plasma generation. In this process, ozone generation resulting from plasma production must also be minimized. According to domestic and international regulatory trends, there are currently no guidelines in any country worldwide regarding the evaluation of plasma-based medical devices for wound treatment. Although academic research on plasma has a long history, there have been no commercialization cases to date regarding its application as a medical device for physical therapy, where safety must be a critical consideration.

[0008] Plasma involves the coexistence of therapeutically suitable reactive oxygen species and ozone, which can be fatal to the human body. When designing plasma-based medical devices for commercialization, the electrode structure and function must be primarily reviewed. In summary, for plasma devices capable of performing medical treatments, the electrode structure, plasma generation efficiency, and ozone suppression become the greatest challenges for commercialization.

[0009] Accordingly, the applicant has devised a plasma pad with a floating electrode structure in which plasma is directly generated between the skin and the electrode using the human body skin as a ground electrode, which exhibits excellent electromagnetic stability even when attached to the skin and also suppresses ozone generation.

[0010] The present invention aims to provide a plasma electrode pad and a plasma treatment device capable of performing medical treatment using plasma formed on the skin attached to the skin of the human body.

[0011] To achieve the above objective, the present invention relates to a floating type plasma electrode pad in which the skin of the human body functions as a ground electrode and plasma is generated between the skin of the human body and the plasma electrode by a voltage applied to a plasma electrode close to the skin of the human body, comprising: a plasma electrode made of a conductive metal thin film; a flexible dielectric thin film made of a polymer material that is laminated on the plasma electrode and forms a micro-discharge into a space separated from the skin of the human body by a predetermined distance; and a spacer laminated on the dielectric thin film to separate the dielectric thin film from the skin of the human body by a predetermined distance, wherein the spacer is provided as a fiber material woven such that fiber bundles form a multilayer structure.

[0012] In addition, the present invention is a floating type plasma treatment device in which the human skin functions as a ground electrode, and plasma is generated between the human skin and the plasma electrode by a voltage applied to a plasma electrode close to the human skin, wherein the device comprises: a plasma electrode made of a conductive metal thin film; a flexible dielectric thin film made of a polymer material that is laminated on the plasma electrode and forms a micro-discharge in a spaced-away space separated from the human skin by a predetermined distance; a spacer laminated on the dielectric thin film that separates the dielectric thin film by a predetermined distance from the human skin; a power supply that applies a DC voltage to the plasma electrode with a predetermined duty cycle; and a ground pad connected to the power supply and in contact with the human skin, wherein plasma having a human-compatible electromagnetic wave generation amount is output under DC power conditions.

[0013] In addition, the present invention is further characterized by a floating type plasma electrode pad in which the human skin functions as a ground electrode, and plasma is generated between the human skin and the plasma electrode by a voltage applied to a plasma electrode close to the human skin, comprising: a plasma electrode made of a conductive metal thin film; a flexible dielectric thin film made of a polymer material that is laminated on the plasma electrode and is spaced apart from the human skin by a predetermined distance to form a micro-discharge in a spaced-away space; and a spacer having one surface laminated on the dielectric thin film to space the dielectric thin film by a predetermined distance from the human skin and having a predetermined opening ratio, wherein the other surface of the spacer contacts the skin to generate plasma directly on the skin through a void formed by the predetermined opening ratio, and the irradiation pattern of the plasma is dot-shaped due to the void.

[0014] According to the present invention, plasma is generated through the voids of a spacer in contact with the skin, and there is an advantage that plasma for treatment is directly generated on the affected area.

[0015] In addition, the present invention generates therapeutic plasma by customizing DC power, which offers superior electromagnetic safety compared to AC power and has the advantage of enabling plasma treatment to be performed even with low power.

[0016] Furthermore, the present invention uses a hygienic fiber material with excellent contact with the affected area as a spacer. In this case, the multilayer fiber bundle forms a cavity particularly suitable for plasma generation. Additionally, since the spacer is a fiber material, it possesses inherent ozone hygroscopicity, which has the advantage of maximizing the efficiency of applying a photocatalyst or active catalyst to the multilayer fiber bundle.

[0017] Furthermore, the plasma electrode pad attached to the affected area is of a floating type and does not require a separate ground electrode, resulting in a simple configuration. According to the present invention, the plasma electrode pad can be made into a consumable item. The present invention performs plasma treatment by attaching and detaching the plasma electrode pad to a power supply, and the plasma electrode pad can be separated from the power supply after treatment. Consequently, the plasma electrode pad can remain attached to the affected area even after plasma treatment performed via power connection. In this case, since the contact surface is made of non-woven fiber material and the simple electrode structure makes it lightweight, the patient has the advantage of being able to carry on with daily life while maintaining the regeneration and hygiene of the affected area with the plasma electrode pad attached.

[0018] [Correction pursuant to Rule 91 21.10.2019] FIG. 1a shows a plasma treatment device according to an embodiment of the present invention, and shows a plasma treatment device during plasma treatment.

[0019] [Correction pursuant to Rule 91 21.10.2019] FIG. 1b shows a plasma treatment device according to an embodiment of the present invention, showing the use of a plasma electrode pad after plasma treatment.

[0020] FIG. 2 shows an exploded perspective view of a plasma electrode pad according to an embodiment of the present invention.

[0021] Figure 3 shows the operation of a plasma electrode pad according to an embodiment of the present invention.

[0022] [Correction pursuant to Rule 91, Oct. 2019, 2021] FIG. 4a shows the results of verifying conditions under which high output characteristics are maintained by varying the frequency (kHz) and duty cycle (μs) for four types of transformers with different winding ratios, and represents the power characteristic results of Transformer #1 and Transformer #2.

[0023] [Correction pursuant to Rule 91, 21.10.2019] Figure 4b shows the results of verifying conditions in which high output characteristics are maintained by varying the frequency (kHz) and duty cycle (μs) for each of the four types of transformers with different winding ratios, and shows the power characteristic results of transformer #3 and transformer #4.

[0024] [Correction pursuant to Rule 91 21.10.2019] Figure 5 is an experimental result showing the optical generation size of plasma according to frequency (kHz) and off-duty time.

[0025] [Correction pursuant to Rule 91 21.10.2019] Figure 6 shows the gas concentration results generated under the plasma intensity conditions of Figure 5.

[0026] [Correction pursuant to Rule 91 21.10.2019] FIG. 7 shows an experimental plasma electrode pad composed of nine types of materials as spacers for performance evaluation.

[0027] [Correction pursuant to Rule 91 21.10.2019] Figure 8 shows the configuration of a plasma electrode module for an experiment.

[0028] [Correction pursuant to Rule 91, Oct. 21, 2019] Fig. 9 shows the number of plasma generation and the average plasma area photographed in a dark room by operating the plasma electrode pad according to the experimental example. Fig. 10 is a table summarizing the number of plasma and the average area for each of the nine types of materials according to Fig. 7, using the experimental method according to Fig. 9.

[0029] Figure 11 shows tomographic images of six types of nonwoven fabric materials.

[0030] Figure 12 shows the plasma generation efficiency by operating a flexible plasma electrode composed of a nonwoven fabric material according to Figure 11 as a spacer.

[0031] Figure 13 shows the results of testing the relationship between the opening ratio of the nonwoven fabric material and the plasma generation efficiency according to Figure 11.

[0032] Figure 14 is a diagram of the experimental setup for measuring the gas generated during plasma generation.

[0033] Figure 15 shows the amount of ozone generated according to the measurement interval.

[0034]

[0035] Explanation of the symbols

[0036] 1: Floating Plasma Therapy Device

[0037] 3: Skin

[0038] 33: Power cable

[0039] 35: Grounding pad

[0040] 10: Floating Plasma Pad

[0041] 100: Adhesive cover

[0042] 1001: Adhesive

[0043] 1003: Communion

[0044] 101: Plasma electrode

[0045] 1011: Terminal

[0046] 103: Dielectric thin film

[0047] 1031, 1051: Functional coatings

[0048] 105: Spacer

[0049]

[0050] The present invention will be described in detail below with reference to the contents described in the attached drawings. However, the present invention is not limited or restricted by exemplary embodiments. Identical reference numerals in each drawing indicate components that perform substantially the same function.

[0051] The purpose and effects of the present invention may be naturally understood or become clearer through the following description, and the purpose and effects of the present invention are not limited solely to the description below. Furthermore, in describing the present invention, if it is determined that a detailed description of known technology related to the present invention may unnecessarily obscure the essence of the present invention, such detailed description will be omitted.

[0052] [Correction pursuant to Rule 91, 21.10.2019] FIG. 1a shows a plasma treatment device (1) according to an embodiment of the present invention, showing the plasma treatment device (1) during plasma treatment, FIG. 1b shows a plasma treatment device (1) according to an embodiment of the present invention, showing the use of the plasma electrode pad (10) after plasma treatment.

[0053] Referring to FIG. 1a, the plasma treatment device (1) may be composed of a plasma electrode pad (10), a grounding pad (35), and a power supply (30). In the plasma treatment device (1) according to the present embodiment, the skin of the human body functions as a grounding electrode, and only one electrode mold is provided on the plasma electrode pad (10). The plasma treatment device (1) according to the present embodiment is provided as a floating type that generates plasma between one electrode and the skin (3) of the human body. Accordingly, the electrode module according to the present embodiment is distinguished from the Direct type (Direct DBD), in which plasma is discharged between electrodes and the discharged plasma is indirectly irradiated onto the skin.

[0054] In the plasma treatment device (1) according to the present embodiment, the plasma electrode pad (10) can be connected to and disconnected from the power supply (30). Accordingly, the plasma electrode pad (10) can be configured as a consumable. Additionally, according to the present embodiment, since the plasma electrode pad (10) is of the floating type (FE-DBD), it can be provided with a simple structure without a ground electrode on the pad. The plasma electrode pad (10) according to the present embodiment grounds the human skin. In the plasma treatment device (1), a separate ground pad (35) that contacts the human skin can be provided as a separate nozzle. The ground pad (35) is connected to the power supply (30) and can be used semi-permanently together with the plasma treatment device (1).

[0055] In summary, the plasma treatment device (1) according to one embodiment is a floating type in which the skin of the human body functions as a ground electrode, and plasma is generated between the skin of the human body and the plasma electrode by a voltage applied to the plasma electrode close to the skin of the human body.

[0056] A plasma treatment device (1) comprises a plasma electrode (101, FIG. 2) made of a malleable metal thin film and a flexible dielectric thin film (103, FIG. 2) made of a polymer material that is laminated on the plasma electrode (101, FIG. 2) and forms a micro-discharge in a spaced-away space that is spaced apart from the skin of a human body at a predetermined distance. Additionally, the plasma treatment device (1) comprises a spacer (105, FIG. 2) that is laminated on the dielectric thin film (103, FIG. 2) and separates the dielectric thin film (103, FIG. 2) from the skin of a human body at a predetermined distance. The plasma electrode (101), the dielectric thin film (103), and the spacer (105) constitute a plasma electrode pad (10).

[0057] Additionally, the plasma treatment device (1) includes a power supply (30) that applies a DC voltage to a plasma electrode (101) at a predetermined duty cycle. Additionally, the plasma treatment device (1) includes a grounding pad (35) connected to the power supply (30) and in contact with the skin of a human body. The plasma treatment device (1) outputs plasma having an electromagnetic wave generation amount that is compatible with the human body under DC power conditions. The plasma electrode pad (10) according to the present embodiment will be described later through FIGS. 2 and 3.

[0058] Referring to FIG. 1b, it can be seen that after plasma treatment is performed with the plasma treatment device (1) according to FIG. 1a, the plasma electrode pad (10) is separated from the plasma treatment device (1) and the plasma electrode pad (10) is utilized as is even after the treatment is completed. Even if the plasma electrode pad (10) according to the present embodiment is separated from the power cable (33), the spacer (105) in contact with the skin can protect the affected area as is and is made of a fiber material that can secure the regenerative power of the wound, so there is no foreign sensation to the patient.

[0059] In addition, even if separate exudate or pus is generated at the affected area, the spacer (105) is made of a fiber material and can properly absorb it, and the patient can continue their daily life as it is attached and fixed to the affected area through the adhesive cover (100). Therefore, the plasma electrode pad (10) according to the present embodiment functions as an electrode module for plasma treatment of the patient, and at the same time can serve as a patch or band that protects the affected area for a predetermined period.

[0060] The power supply (30) applies a DC voltage to the plasma pad (10) at a predetermined duty cycle. In this embodiment, it is noted that the power supply (30) applies a DC voltage for plasma generation. Compared to using AC voltage, DC voltage has significantly superior electromagnetic stability during plasma treatment. In the safety evaluation items for medical devices, there are electromagnetic standards in accordance with the notification of the Ministry of Food and Drug Safety regarding the “Common Standards for Electromagnetic Safety of Medical Devices.” Therefore, in order to implement a plasma electrode pad (10) as a medical device for wound treatment, it must be possible to satisfy the above standard conditions. While it is extremely difficult to satisfy the Common Standards for Electromagnetic Safety when implementing an AC power supply (30), a DC voltage-based plasma generation module can satisfy the electromagnetic standards for human body safety.

[0061] In this case, if the DC voltage of the power supply (30) is used as the power source without separate signal processing, the plasma generation efficiency may be significantly lower than that of the AC power source. Therefore, in order to increase the plasma generation efficiency in the DC voltage power, the power supply (30) according to the present embodiment applies a pulse-shaped DC voltage having a predetermined duty cycle. In this case, the power supply (30) can increase the plasma generation efficiency by mimicking the effect of the AC power source even though it uses DC.

[0062] In this embodiment, the power supply (30) generates plasma by outputting a DC voltage in the range of greater than 0 kV and less than or equal to 5 kV having a predetermined duty cycle. More specifically, the power supply (30) according to this embodiment has a pulse frequency of 130 kHz to 150 kHz and an off-duty time in the range of 2 μs to 4 μs. The voltage conditions of the power supply (30) above are considered in light of the condition of ozone generation amount permissible to the human body among the medical device performance evaluation items. Medical devices are notified that ozone generation must be 0.05 ppm or less as a criterion for determining whether the potential harm to the human body caused by ozone generated during atmospheric pressure plasma generation is at an appropriate level.

[0063] Plasma inevitably entails ozone generation during the ionization process. Therefore, minimizing ozone generation is a technical issue in the implementation of a plasma electrode pad (10) for medical devices. Although this will be explained in more detail in the experimental examples described later, ozone generation can be minimized by controlling power conditions along with the photocatalytic or active catalyst coating of the electrode module. It is preferable to understand the power conditions of the power supply (30) according to this embodiment as conditions for lowering the amount of ozone generated by the plasma electrode pad (10) according to this embodiment to 0.05 ppm or less.

[0064] The plasma treatment device (1) may further include a display (31) that indicates whether plasma is generated or the intensity of the plasma. Since plasma is generated when the plasma electrode pad (10) comes into contact with the skin and the skin acts as a ground electrode, it is difficult for the user to visually confirm the generation of plasma. Therefore, in order to check whether the plasma electrode pad (10) is operating normally, the generation or intensity of the plasma may be displayed through a separate display (31).

[0065] The plasma electrode pad (10) according to the present embodiment is described below.

[0066] FIG. 2 shows an exploded perspective view of a plasma electrode pad (10) according to an embodiment of the present invention. FIG. 3 shows the operation of a floating plasma pad according to an embodiment of the present invention.

[0067] Referring to FIGS. 2 and 3, the plasma electrode pad (10) is attached directly to the skin (3) for treatment like a patch. The plasma electrode pad (10) may include an adhesive cover (100), a plasma electrode (101), a dielectric thin film (103), and a spacer (105).

[0068] A plasma electrode pad (10) according to one embodiment comprises: a plasma electrode (101) made of a conductive metal thin film; a flexible dielectric thin film (103) made of a polymer material that is laminated on the plasma electrode (101) and forms a micro-discharge in a spaced-away spaced apart from the skin of a human body at a predetermined distance; and a spacer (105) laminated on the dielectric thin film (103) and spaced the dielectric thin film at a predetermined distance from the skin of a human body, wherein the spacer (105) is provided as a fiber material woven such that fiber bundles form a multilayer.

[0069] A plasma electrode pad (10) according to another embodiment comprises: a plasma electrode (101) made of a conductive metal thin film; a flexible dielectric thin film (103) made of a polymer material that is laminated on the plasma electrode (101) and is spaced apart from the skin of a human body at a predetermined distance to form a micro-discharge in a spaced-away space; and a spacer (105) having one surface laminated on the dielectric thin film (103) to space the dielectric thin film (103) from the skin of a human body at a predetermined distance and having a predetermined opening ratio, wherein the other surface of the spacer (105) contacts the skin to generate plasma directly on the skin through a void formed at a predetermined opening ratio, and the plasma irradiation pattern is dot-shaped due to the void.

[0070] Below, the detailed configuration of the plasma electrode pad (10) according to each embodiment is described.

[0071] Referring to FIG. 2, the flexible plasma electrode pad (10) has a spacer (105), a dielectric film (103), a plasma electrode (101), and an adhesive cover (100) stacked sequentially from the skin (3).

[0072] The adhesive cover (100) functions as a cover for the plasma pad (10). The adhesive cover (100) insulates the plasma electrode (101) and may be provided with a flexible material. In this embodiment, the material of the adhesive cover (100) may be silicone, PDMS, or synthetic rubber. The adhesive cover (100) may include an adhesive portion (1001) for attaching the electrode pad to the skin (3). The adhesive cover (100) with the adhesive portion (1001) formed forms a larger area than the plasma electrode (101), dielectric film (103), and spacer (105). The adhesive portion (1001) has a known adhesive material applied to its lower surface and is attached to the skin (3) to fix the plasma electrode pad (10).

[0073] The adhesive cover (100) has a through hole (1003) formed in one area. The through hole (1003) allows the power terminal (1011) of the plasma electrode (101) provided at the bottom of the adhesive cover (100) to be exposed to the outside.

[0074] The plasma electrode (101) is made of a conductive metal thin film. It is preferable that the plasma electrode (101) be selected from a flexible material with excellent conductivity. As an example, copper (Cu) material has been widely used in plasma electrode modules. However, the plasma electrode pad (10) according to the present embodiment is positioned close to the skin for medical use. Therefore, it is more preferable to construct the plasma electrode (101) with carbon material rather than copper (Cu) material, which generates excessive heat and has poor durability.

[0075] The plasma electrode (101) may include a terminal (1011) for connecting a power cable (33). The terminal (1011) may be configured to protrude upward in a button shape, as in the embodiment of FIG. 2. The terminal (1011) may be configured at the distal end of the plasma electrode (101) in the plane direction, but in this case, there is the inconvenience of having to connect the power cable (33) to the side of the thin plasma electrode pad (10). In addition, if the terminal is exposed at the distal end of the plasma electrode pad (10) after the power cable (33) is disconnected from the plasma electrode pad (10), the exposed terminal may be bothersome to the patient. Therefore, in this embodiment, the terminal (1011) is configured to protrude upward from the plasma electrode (101).

[0076] The dielectric thin film (103) can be provided as a flexible configuration of a polymer material that is laminated on a plasma electrode (101) and is spaced apart from the human skin (3) by a predetermined distance to form a micro-discharge in a spaced-away space.

[0077] Generally, rigid materials are used as dielectrics in plasma electrodes, and it is difficult to find commercialized examples of products in which polymer materials are used as dielectric materials. This is because commonly used rigid dielectrics have high dielectric constants of 6 to 10, which offers the advantage of facilitating plasma generation. However, due to the high dielectric constant of rigid dielectrics, a large amount of ozone (O3) is generated during plasma creation, which poses a problem for the biomedical applications intended by this invention. On the other hand, polymer materials have low dielectric constants, making plasma generation difficult, but they possess flexible characteristics.

[0078] In this embodiment, the dielectric thin film (103) may be composed of PDMS or PI material. Although the thinner the thickness of the dielectric thin film (103), the flexibility improves, the voltage breakdown thickness of each material must be considered so that the high voltage range for plasma generation becomes the breakdown voltage and the Dielectric Breakdown phenomenon does not occur. The voltage breakdown thickness varies depending on the characteristics of each polymer material. For the polymer materials PDMS and PI in this embodiment, a thickness of at least 0.1 mm must be maintained to prevent voltage breakdown. Therefore, it is preferable that the dielectric thin film (103) be formed with a thickness of at least 0.1 mm but within a range of 1 mm or less to ensure flexibility.

[0079] The dielectric thin film (103) may be provided with photocatalyst or active catalyst particles applied for ozone absorption. The dielectric thin film (103) may be coated with a functional coating (1031) of a photocatalyst or active catalyst to reduce the amount of ozone generated. The catalyst material may include TiO2 or MnO2.

[0080] A spacer (105) is laminated onto a dielectric film to separate the dielectric film (103) from the human skin (3) by a predetermined distance. At this time, the spacer (105) is characterized by being provided as a fiber material woven so that fiber bundles form a multilayer structure. In a floating type DBD plasma electrode structure, the plasma electrode pad (10) according to the present embodiment, which uses the human skin (3) as a ground electrode, inevitably requires a predetermined clearance distance between the dielectric film (103) and the skin (3). Only when a clearance distance exists can atmospheric pressure plasma be formed in the clearance space. To this end, the plasma electrode pad (10) is provided with a configuration of a spacer (105) that separates the skin (3) and the dielectric film (103). Here, since a clearance space is theoretically required, it is common to adopt a mesh structure with through holes formed in the spacer. That is, it is natural for those skilled in the art to adopt a mesh film with holes that are visible to the naked eye as the spacer. However, regarding the spacer (105) according to the present embodiment, as a result of testing various materials through experimental examples to be described later, it was confirmed that a fiber material with a complex structure, which is difficult to view as a conventional theoretical mesh structure, functions more effectively as a spacer for plasma generation. Contrary to the expectation that plasma would not be generated because the perforations in the fiber material with a complex structure are barely visible to the naked eye and thus a sufficient space for plasma generation is not formed, the spacer having a random complicate structure showed an excellent plasma generation effect in the following experimental examples.

[0081] Accordingly, the spacer (105) according to the present embodiment is characterized by being provided with a fiber material in which fiber bundles are formed into a multilayer layer, and generates plasma between the spaced spaces of the fiber bundles. The spacer (105) has a random complicate structure in which fiber bundles form a multilayer layer. At this time, in the present specification, the ratio of the open space between the fibers forming the multilayer layer and the ratio of the open space to the space occupied by the fibers are defined as the opening ratio in a cross-section of the multilayer layer viewed from above. It is preferable that the spacer (105) according to the present embodiment be provided with an opening ratio of 30% or more. Through the experimental examples to be described later, among the fiber material spacers (105), materials having various opening ratios were tested. As a result, the opening ratio and plasma generation efficiency had a low proportional relationship in the opening ratio range of 20% or less, the proportional relationship improved in the range of 20% to 30%, and showed high plasma generation efficiency at 30% or more. In light of this, it can be seen that there is significant critical importance to plasma generation efficiency under conditions where the opening ratio is 30% or more. The spacer (105) according to the present embodiment is a multilayer fiber material with a random complicated structure and has a condition where the opening ratio is 30% or more.

[0082] More specifically, the spacer (105) is preferably provided as a nonwoven fabric material. The nonwoven fabric consists of fiber bundles arranged in a multilayer structure, in contrast to gauze woven from rayon or synthetic fibers in a mesh structure. The reasons why the nonwoven fabric material is more suitable than gauze with a mesh structure as the spacer (105) can be summarized as follows. First, according to the experimental examples to be described later, the plasma generation efficiency of the nonwoven fabric fibers was superior to that of the mesh structure. Second, the mesh structure has a large individual area of ​​the perforated holes. In this case, the thickness of a single layer of the woven fibers is what separates the skin (3) from the spacer. On the other hand, the nonwoven fabric having a multilayer structure of fiber bundles consists of multiple loosely woven fiber bundles forming a multilayer structure, while forming random spaces between the fiber bundles. At this time, there is a concern that the dielectric film (103) may be adhered to the perforations of the relatively large mesh structure of the spacer (105) attached to the skin during the adhesion process, thereby reducing the efficiency of the plasma generation space. On the other hand, even if the non-woven fabric is adhered to the skin by adhesion and compression, the fiber bundles are composed of multiple layers, making it difficult for the skin (3) and the dielectric film (103) to come into direct contact. Therefore, by applying the non-woven fabric material as the spacer (105), the affected area of ​​the skin (3) can be protected more hygienically, and the plasma generation efficiency becomes excellent. Thirdly, the non-woven fabric composed of multiple fiber bundles can reduce ozone generation due to the characteristics of the material itself. The spacer (105) according to the present embodiment maintains the concentration of ozone generated around the plasma at 0.05 ppm or less. To this end, the spacer (105) may be provided with photocatalyst or active catalyst particles applied for ozone absorption. The spacer (105) may be coated with a functional coating (1051) of a photocatalyst or active catalyst to reduce the amount of ozone generated. The catalyst may include TiO2 or MnO2. Fourth, in this embodiment where a nonwoven fabric is used as the spacer (105), the efficiency of the photocatalyst coating can be maximized.In this embodiment, photocatalytic particles are applied to the nonwoven fabric by spraying. In this case, while the mesh-structured spacer has a small area for photocatalytic application, the nonwoven fabric has photocatalytic particles attached to multilayer fiber bundles, thereby maximizing ozone absorption performance.

[0083] FIG. 3 illustrates the operation of the plasma electrode pad (10) according to the present embodiment. Referring to FIG. 3, the plasma (P) formed on the surface of the actual skin (3) takes the form of a dot. For better understanding, FIG. 3 shows the formation of the plasma (P) viewed from the bottom surface of the spacer (105) in a separate manner.

[0084] Below, experimental examples for deriving power conditions of the power supply (30) according to the present embodiment, experimental examples for deriving material conditions of the spacer (105), and experimental examples for checking ozone and active oxygen are described.

[0085]

[0086] Experimental Example 1. Power Supply Power Conditions

[0087] This experiment checks the duty cycle and frequency of the pulses that are optimal for plasma generation due to the characteristics of the power supply (30) that uses direct current.

[0088] Figure 4 shows the results of verifying conditions under which high output characteristics are maintained by varying the frequency (kHz) and duty cycle (μs) for four types of transformers with different winding ratios. Figure 4a shows the power characteristic results of transformer #1 and transformer #2. Figure 4b shows the power characteristic results of transformer #3 and transformer #4. Referring to the results in Figure 4, plasma generation was possible in the range of 100 kHz to 160 kHz in common for the four types of transformers with different winding ratios.

[0089] Figure 5 shows the experimental results representing the optical generation magnitude of plasma according to frequency (kHz) and off-duty time. The X plasma intensity and Y plasma intensity indicated in Figure 5 are conditions selected based on the change in optical intensity of the plasma according to changes in frequency and off-duty time. The plasma generation region was classified based on whether ozone in the gas generated during plasma generation was 0.05 ppm or less.

[0090] The measurement of plasma optical intensity was based on the results of optical emission spectroscopy (@360nm). For the measurement of plasma optical intensity, light with a wavelength of 360nm was selected from among the various wavelengths of light generated in atmospheric pressure plasma, and changes in optical intensity under different conditions were observed. The range in the changes in optical intensity where plasma generation is possible and ozone levels are 0.05 ppm or lower was designated as the Y plasma intensity region.

[0091] FIG. 6 shows the gas concentration results generated under the plasma intensity conditions of FIG. 5. Referring to FIG. 6, the amount of O3 and NO2 generated in the material of each spacer (105) in the X plasma intensity region is shown, as well as the amount of O3 and NO2 generated when the photocatalytic functional layer (1031, 1051) is included. Here, the selected spacer (105) materials OCL15, OCP16, OCP22, OCP30, OCP40, and CCT50 are all non-woven fabric materials, and experimental examples in which the corresponding materials were selected will be described later. Meanwhile, it is desirable for O3 to be generated at 0.05 ppm or less, and it is desirable for NO2 to be generated in large quantities as it is an active gas beneficial for sterilization.

[0092] Referring to Figure 6, it can be seen that the amount of ozone generated exceeds 0.05 ppm even when a functional layer of photocatalyst for ozone absorption is applied at X plasma intensity. On the other hand, at Y plasma intensity, it can be seen that the amount of ozone generated is 0.05 ppm or less when using nonwoven materials such as OCL15, OCP16, OCP40, and CCT50. In particular, it is noteworthy that at X plasma intensity, the amount of ozone generated and the amount of nitrogen dioxide generated are similar. Conversely, under the Y plasma intensity condition, the amount of ozone generated is reduced, while the amount of nitrogen dioxide generated is relatively high.

[0093] The operating conditions of the power supply for X plasma intensity are Frequency 120kHz, Off duty time: 5.08μs, plasma turn-on time: 0.426ms, Voltage: 0~7kV. The operating conditions of the power supply (30) for Y plasma intensity are Frequency 140kHz, Off duty time: 2.64μs, plasma turn-on time: 0.426ms, Voltage: 0~4kV.

[0094] According to the experimental results of FIGS. 4 to 6, the power supply (30) according to the present embodiment has a pulse frequency of 130 kHz to 150 kHz and an off duty time in the range of 2 μs to 4 μs.

[0095]

[0096] Experimental Example 2. Experiment on Plasma Generation Efficiency by Spacer Material

[0097] 2-1. mash structure vs complicated structure

[0098] Figure 7 shows an experimental plasma electrode pad composed of nine types of materials as spacers for performance evaluation. Figure 8 shows the configuration of a plasma electrode module for the experiment. Referring to Figure 8, agarose gel was used to function as a ground and correspond to human skin. In the flexible plasma electrode pad according to this experimental example, plasma is generated only when in contact with the human body, and transparent agarose gel was used so that this can be observed from the outside. The agarose gel was prepared by curing a mixture of Agar powder / DI water 10 wt.% at 70°C.

[0099] In FIG. 8, a flexible plasma pad was configured with nine types of materials according to FIG. 7 as the spacer configuration, and plasma generation was tested for each. The nine types of materials presented in FIG. 7 are numbered sequentially from left to right and from top to bottom, and the names of the materials are as follows.

[0100] Number Material Name1PE mesh2non-woven fabric pp-30w3non-woven fabric, smms-15w4non-woven fabric5pp mesh6pp mesh, pp507pp mesh, pp708pp mesh, pp309pp mesh, pp70

[0101] Materials numbered 1, 5 through 9 all have a mesh structure, while materials numbered 2 through 4 are non-woven fabrics composed of fiber bundles arranged in multiple layers. Figure 9 shows the number of plasma generation and the average plasma area captured in a dark room by operating a plasma electrode pad according to an experimental example. The image captured in Figure 9 shows the plasma generation when using the non-woven fabric numbered 3.

[0102] Figure 10 is a table summarizing the number of plasmas and average area for nine types of materials according to Figure 7, using the test method of Figure 9. Referring to Figure 10, serial numbers 3, 6, and 7 corresponded to materials that had excellent numbers of plasmas and plasma areas.

[0103] It is noteworthy that, contrary to theoretical expectations, dot-shaped plasma is emitted from the non-woven material shown in Fig. 9. This is because, in mesh structures such as materials No. 1, 5 through 9, plasma emission naturally occurs in correspondence with the pore shapes of the mesh, whereas the non-woven materials No. 2 through 4 are not materials with pores formed like the actual emitted plasma dots. Additionally, in the experimental method of Fig. 9, the plasma area is 10 pixels 2 Only the plasma areas mentioned above were considered. Here, unlike serial numbers 6 and 7, serial number 3 showed the least variation in the number of plasma generation and area. This corresponds to 10 pixels for each checked plasma count. 2 It is expected that the dot performance generating the above plasma area is superior. As such, it has been described that nonwoven fabric materials are more suitable for plasma electrode pads for wound treatment due to the second to fourth reasons mentioned above, in addition to the plasma generation efficiency. Considering this, regarding the structural characteristics of the spacer material, a material with a complicated structure in which fiber bundles are composed of multilayer layers and randomly intertwined will be superior to a material with a mesh structure.

[0104]

[0105] 2-2. Plasma Characteristics of Complicated Structure Materials Under Different Conditions

[0106] Figure 11 shows scanning electron microscope tomographic images of six types of nonwoven fabric materials. The six types of nonwoven fabric materials are as follows.

[0107] Material Name Thickness Fiber Diameter OCL 15 60㎛ 15㎛ OCP 16 70㎛ 15㎛ OCP 2 2 80㎛ 15㎛ OCP 3 0 1 10㎛ 15㎛ OCP 4 0 1 50㎛ 15㎛ CCT 5 0 1 80㎛ 15㎛

[0108] Figure 12 shows the plasma generation efficiency when operating a flexible plasma electrode composed of a nonwoven fabric material according to Figure 11 as a spacer. Referring to Figure 12, the plasma generated from the OCL15 nonwoven fabric produced almost no streamers (filaments), and the plasma discharged like a glow discharge, making it impossible to count the number of plasmas. It is presumed that the plasma was generated as a glow discharge because the distance between the electrodes narrowed due to the thinnest thickness of the OCL15 nonwoven fabric, which reduced the discharge voltage.

[0109] Figure 13 shows the test results regarding the relationship between the opening ratio of the nonwoven fabric material and the plasma generation efficiency according to Figure 11. In the result table of Figure 13, the y-axis on the right represents the opening ratio (%), and the y-axis on the left represents 10 pixels 2 This represents the number of plasmas emitted as dots over the above area. Here, the aperture ratio is a numerical value quantified as the ratio of the open space to the area formed by the fiber bundles in a tomographic image of the nonwoven fabric taken with a scanning electron microscope.

[0110] Notably, when the aperture ratio of the nonwoven material is 20% or less, the plasma generation efficiency is linear, but the degree of this linearity is not high. The result table in Fig. 13 shows that the plasma generation efficiency increases as the aperture ratio increases. However, the aperture ratio and plasma generation efficiency do not increase linearly over the entire range, and the plasma generation efficiency increased starting from when the aperture ratio was 30% or higher. Synthesizing the results of Figs. 11 to 13, glow discharge occurs at a thickness of 60㎛ or less, as in OCL15. Therefore, it is concluded that the best plasma is generated when the aperture ratio is 30% or higher under conditions of a thickness of 60㎛ to 100㎛.

[0111]

[0112] Experimental Example 3. Gas Generation Test

[0113] Figure 14 is a configuration diagram of an experiment for measuring gases generated during plasma generation. The gases to be measured are harmful ozone and beneficial nitrogen dioxide. The power conditions for the initial gas measurement were set to a frequency of 120 kHz, a duty time of 5.08 μs, and a delay time of 0.426 ms. The ground electrode corresponding to the skin is 2 x 1 cm. 2 Agarose gel was used. The measurement interval was at least 1 cm, the height was 2 cm, and the measurement time was repeated 5 times after a 1-minute plasma discharge.

[0114] PDMS was used as the dielectric thin film for the plasma electrode pad, and carbon was used as the plasma electrode. In addition, a photocatalyst was applied to the PDMS and spacer to conduct experiments under conditions of excellent ozone absorption. Figure 15 shows the amount of ozone generated according to the measurement interval. Referring to Figure 15, it was confirmed that the ozone decreased significantly as the distance between the electrode and the gas detector tube increased by 1 cm. According to the Framework Act on Environmental Policy and relevant standards for indoor air purifiers, when evaluating the amount of ozone generated, a dust collection test chamber or a spatial volume of 40 m³ 3 ±10m3 Measurements are taken in an indoor space with a ceiling height of 3m or less. The above test conditions are because ozone is problematic when inhaled into the human respiratory system. The plasma electrode pad (10) according to the present embodiment is attached to the skin, and even if used on the face, it can be placed at least 1 to 3 cm away from the nose or mouth, which are part of the human respiratory system. In the experimental results of FIG. 15, the amount of ozone generated is 0.05 ppm or less even when only a distance of 3 cm is formed from the plasma electrode pad.

[0115] However, in order to ensure maximum stability, this experimental example aimed to optimize conditions so that ozone generation is confirmed to be 0.05 ppm or less even when the distance between the plasma electrode pad and the detector tube is within 1 cm. The result can be seen in the experiment according to the power supply (30) conditions described in Fig. 6 above. Referring again to Fig. 6, Fig. 6 shows the results measured when the detector tube is 1 cm in the experimental configuration diagram of Fig. 14. As the thickness of the nonwoven fabric increases, the trend line of the generated gas concentration showed a characteristic of gradually decreasing. As a result of this experiment, when OCL15, OCP16, OCP40, and CCT50 were used as spacers, ozone generation was detected to be 0.05 ppm or less even at a measurement distance of 1 cm.

[0116] Although the present invention has been described in detail above through representative embodiments, those skilled in the art will understand that various modifications can be made to the above-described embodiments within the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims set forth below as well as all modifications or variations derived from the claims and equivalent concepts.

[0117]

[0118]