Atmospheric pressure low-temperature plasma apparatus and method for generating atmospheric pressure low-temperature plasma jet suitable for human body

Abstract

Provided is an atmospheric pressure low-temperature plasma apparatus capable of sufficiently separating a high-voltage applying part for plasma generation and a human body surface on which a plasma jet acts.　The present invention comprises: a plasma generation part 20 in which a first electrode 22a and a second electrode 22b, which are belt-shaped and spirally provided around a dielectric tube 21, are combined to form a double helix; a cylindrical exterior part 12 provided to cover an energized part in order to hold the dielectric tube 21; a power source device 30 which is connected between the electrodes and supplies an alternating current; and a gas supplying device 50 which supplies a plasma processing target gas from one end of the dielectric tube 21. A plasma jet containing a gas processed by atmospheric pressure low-temperature plasma generated in the dielectric tube 21 is discharged from the other end of the dielectric tube 21, said other end being provided in a manner of being projecting from the exterior part 12.

Description

Atmospheric pressure low temperature plasma device and method for generating atmospheric pressure low temperature plasma jet that is beneficial to the human body

[0001] The present invention relates to an atmospheric pressure low-temperature plasma device and a method for generating an atmospheric pressure low-temperature plasma jet that is suitable for the human body.

[0002] Treatments using atmospheric pressure low-temperature plasma are being performed to achieve cosmetic effects such as sterilization, removal of impurities, and improved penetration of beauty serums. Various types of plasma generators have been proposed for such treatments using atmospheric pressure low-temperature plasma. For example, Patent Document 1 (JP-A-2003-102666) relates to an atmospheric pressure plasma device for improving various skin problems or for skin beautification, and discloses a remote-type atmospheric pressure plasma device in which a plasma spraying device is connected independently to a main controller. It states that in this atmospheric pressure plasma device, the atmospheric pressure plasma is sprayed entirely through a ground electrode, so no electrical stimulation is applied to the skin.

[0003] Special Publication No. 2020-520534

[0004] However, in Patent Document 1, the voltage electrode to which a high voltage of several kV AC is applied and the ground electrode are still placed close to the skin, so it was recognized that there was a need to more reliably prevent current leakage into the human body.

[0005] In order to solve the above and other problems, the present invention aims to provide an atmospheric pressure low-temperature plasma device and a method for generating an atmospheric pressure low-temperature plasma jet that are suitable for the human body, and that can ensure the safety of the human body with respect to atmospheric pressure low-temperature plasma generation by sufficiently separating the human body on which the atmospheric pressure low-temperature plasma jet acts from the part to which high voltage is applied for generating atmospheric pressure low-temperature plasma.

[0006] In order to achieve the above and other objects, one aspect of the present invention is an atmospheric pressure low-temperature plasma device that is suitable for the human body, comprising: an atmospheric pressure low-temperature plasma generating unit that is composed of a cylindrical dielectric tube that forms a gas flow path and a double-spiral plasma generating electrode pair formed by combining a first electrode and a second electrode, which are strip-shaped electrodes that are each spirally arranged around the periphery of the tube; a cylindrical exterior part that is arranged to cover a current-carrying part including the plasma generating electrode pair so as to be able to hold the dielectric tube of the atmospheric pressure low-temperature plasma generating unit; a power supply part that is connected between the first electrode and the second electrode and supplies AC current to the plasma generating electrode pair; and a gas supply part that supplies a gas to be plasma-treated from one end of the dielectric tube into the dielectric tube, and a plasma jet containing a gas that has been treated by the atmospheric pressure low-temperature plasma generated in the dielectric tube is emitted from the other end of the dielectric tube that protrudes from the exterior part.

[0007] The gas supply unit may be configured to be able to supply two or more types of gases to be plasma treated.

[0008] It is preferable that the other end of the dielectric tube, which is a plasma jet outlet, and the end of the plasma generating electrode pair are spaced apart by at least 11 mm.

[0009] An injection needle may be provided at the other end of the dielectric tube, which is a plasma jet outlet.

[0010] In this case, it is preferable that the needle base end of the needle tube of the injection needle and the end of the plasma generating electrode pair are spaced apart by at least 11 mm.

[0011] Another aspect of the present invention is a method for generating an atmospheric pressure low-temperature plasma jet that is suitable for the human body, which comprises combining a first electrode and a second electrode, which are strip-shaped electrodes each arranged spirally around a cylindrical dielectric tube that forms a flow path for a gas to be treated, to form a double-spiral plasma-generating electrode pair, supplying an AC current between the first electrode and the second electrode of the plasma-generating electrode pair, supplying a gas to be plasma-treated from one end of the dielectric tube into the dielectric tube, and releasing a plasma jet containing gas treated by the atmospheric pressure low-temperature plasma generated in the dielectric tube from the other end of the dielectric tube that protrudes from the exterior.

[0012] According to the present invention, it is possible to sufficiently separate the human body surface on which the atmospheric pressure low-temperature plasma jet acts from the part to which high voltage is applied for generating atmospheric pressure low-temperature plasma, thereby ensuring the safety of the human body with respect to atmospheric pressure low-temperature plasma generation, and an atmospheric pressure low-temperature plasma device and method for generating an atmospheric pressure low-temperature plasma jet are provided that are suitable for the human body.

[0013] Fig. 1 is a schematic diagram showing the overall configuration of an atmospheric pressure low-temperature plasma apparatus according to an embodiment of the present invention; Fig. 2 is a schematic perspective view of a plasma generation apparatus provided in the atmospheric pressure low-temperature plasma apparatus according to an embodiment of the present invention; Fig. 3 is a partial vertical cross-sectional view of the plasma generation apparatus illustrated in Fig. 2; Fig. 4 is a cross-sectional view of the plasma generation apparatus illustrated in Fig. 3; Fig. 5 is a partial side view illustrating a modified example of the plasma generation apparatus;

[0014] The present invention will be described below with reference to the drawings based on embodiments thereof. Note that the present invention is not limited to the following embodiments. Furthermore, the drawings referred to in the following description merely show the shapes, sizes, and positional relationships in a schematic manner to enable understanding of the contents of the present disclosure. In other words, the present invention is not limited to only the shapes, sizes, and positional relationships exemplified in the drawings.

[0015] <Atmospheric Pressure Low-Temperature Plasma Apparatus> First, the overall configuration of an atmospheric pressure low-temperature plasma apparatus according to one embodiment of the present invention will be described. Figure 1 shows a schematic diagram of an example of the overall configuration of an atmospheric pressure low-temperature plasma apparatus 1 according to this embodiment. As shown in Figure 1, the atmospheric pressure low-temperature plasma apparatus 1 mainly comprises a plasma generation device 10 for generating atmospheric pressure low-temperature plasma, a power supply device 30 for supplying plasma generation power to the plasma generation device 10, a pump 40 for supplying a gas to be treated by atmospheric pressure low-temperature plasma to the plasma generation device 10, and a gas supply device 50 for selectively supplying the gas to be treated.

[0016] In FIG. 1 , a gas to be subjected to plasma processing is supplied into a plasma generation device 10 through a conduit 70 connected to its upper opening. The gas to be processed is supplied to a pump 40 from multiple gas supply sources connected to a gas supply device 50 through a conduit 60 via a supply gas switching valve (not shown) provided in the gas supply device 50. The supply gas switching valve may be manually operated or may be electrically or other power-switched. When the gas to be processed is air, ambient air is taken into the gas supply device 50 through the conduit 60. The gas supply device 50 may mix multiple types of gases in appropriate ratios to generate a mixed gas. The gas from the gas supply device 50 is pressure-fed to the plasma generation device 10 by an appropriate type of pump 40.

[0017] The gas to be treated introduced into the plasma generator 10 through the conduit 70 is treated by the atmospheric pressure low-temperature plasma generated in the plasma generator 10, and is emitted to the outside from the end opening of the dielectric tube 21 as a plasma jet PJ containing various active species generated according to the type and composition of the gas. The plasma jet PJ is applied to the surface of human skin S, for example, to sterilize the skin surface, decompose and remove waste products, activate skin cells, and so on.

[0018] <Plasma Generation Apparatus> Next, the plasma generation apparatus 10 will be described. Fig. 2 is a perspective view showing a schematic configuration example of the plasma generation apparatus 10, Fig. 3 is a partial longitudinal cross-sectional view of the plasma generation apparatus 10, and Fig. 4 is a transverse cross-sectional view of the plasma generation apparatus 10. The plasma generation apparatus 10 has a plasma generation unit 20 that forms a cylindrical space where atmospheric pressure low-temperature plasma is generated. The plasma generation unit 20 mainly includes a dielectric tube 21 and an exterior unit 12 that has a cylindrical structure and is provided to cover the periphery of the dielectric tube 21. A conduit 70 is connected to one end of the dielectric tube 21, and a gas selected as a processing target is supplied into the dielectric tube 21 from a gas supply device 50 by a pump 40.

[0019] The plasma generating unit 20 has a dielectric tube 21. The dielectric tube 21 is a long, hollow member made of a dielectric material such as glass. The dielectric tube 21 is provided on its outer periphery with a first electrode 22a and a second electrode 22b, each made of a strip-shaped conductive material, and electrode terminals 23a and 23b provided at one end of the first electrode 22a and the second electrode 22b, respectively.

[0020] A space is defined within the dielectric tube 21 in which atmospheric pressure low-temperature plasma is generated. The first electrode 22a and the second electrode 22b are each formed of a thin strip of conductive material. The first electrode 22a and the second electrode 22b are preferably formed of, for example, a thin copper plate or copper foil tape, but are not limited thereto. Other materials may be used as long as they have good electrical conductivity and can be used as electrode materials. As illustrated in FIGS. 2 to 4, the first electrode 22a and the second electrode 22b each have a spiral shape that rotates around the central axis of the dielectric tube 21, and the spiral-shaped first electrode 22a and the second electrode 22b are further arranged to form a double spiral around the central axis. The electrode material of the first electrode 22a and the second electrode 22b is adhered to the outer surface of the dielectric tube 21 by appropriate means.

[0021] As shown in Figures 2 to 4, in the plasma generating unit 20, the portion of the dielectric tube 21 where the first electrode 22a and the second electrode 22b are provided is covered by a substantially cylindrical exterior part 12. The exterior part 12 can be formed by appropriately selecting from insulating resin materials, etc. In this embodiment, the exterior part 12 is formed to have an inner diameter larger than the outer diameter of the dielectric tube 21, and is provided so as to cover the electrode terminals 23a, 23b provided on the first electrode 22a and the second electrode 22b, respectively, and the first electrode 22a and the second electrode 22b disposed therebetween, and is fixed to the outer circumferential surface of the dielectric tube 21 near the electrode terminals 23a, 23b. An electrically insulating material, such as epoxy resin, is filled between the exterior part 12 and the dielectric tube 21, the first electrode 22a, the second electrode 22b, and the electrode terminals 23a, 23b. As a result, the first electrode 22a, the second electrode 22b, and the electrode terminals 23a, 23b, to which a high voltage for plasma generation is applied, are safely isolated from the outside world by the exterior casing 12, and also function as a grip (holder) when a user uses the plasma generating unit 20. Note that instead of providing the exterior casing 12 at a distance from the dielectric tube 21 as shown in the figure, the exterior casing 12 may be provided in close contact with the outer circumferential surface of the dielectric tube 21 so that the first electrode 22a, the second electrode 22b, and the electrode terminals 23a, 23b are completely sealed with the resin material forming the exterior casing 12. In this way, the first electrode 22a, the second electrode 22b, and the electrode terminals 23a, 23b are sealed with an appropriate resin material having electrical insulation properties, which prevents discharge from the electrodes to the human body and minimizes the current flowing through the human body, contributing to safety.

[0022] As illustrated in Fig. 3, in this embodiment, a strip-shaped conductor having a width W that forms each of the electrodes 22a and 22b is spirally wound N times at a winding pitch P. Referring to Fig. 4, each of the electrodes 22a and 22b has a thickness T and is sealed within the exterior part 12. Therefore, the first electrode 22a and the second electrode 22b are disposed opposite each other with the dielectric tube 21 interposed therebetween, sandwiching the cylindrical space within the dielectric tube 21.

[0023] Here, an example of the plasma generation unit 20 will be described. For the first electrode 22a and the second electrode 22b to form a spiral along the outer periphery, where l is the outer circumferential length of the dielectric tube 21, and W is the electrode width and D is the inter-electrode spacing, the relationship 2D + 2W < l must be satisfied. As the inter-electrode spacing D narrows, the applied voltage required to generate plasma increases due to the end effect. Furthermore, as the electrode width W narrows, creeping discharge between the first electrode 22a and the second electrode 22b becomes more likely to be induced. Therefore, as an example, if the outer diameter of the dielectric tube 21 is 4 mm, the outer circumferential length l = 12.6 mm. It was confirmed that atmospheric pressure low-temperature plasma can be stably generated by setting D = 2 mm and W = 3 mm so that 2D + 2W < 12.6 mm is satisfied.

[0024] When a high voltage is applied between the first electrode 22a and the second electrode 22b by the power supply device 30 described later, a dielectric barrier discharge occurs between the first electrode 22a and the second electrode 22b, and atmospheric pressure low temperature plasma is generated in the cylindrical space inside the dielectric tube 21. In the cylindrical space of the plasma generation device 10, the generated atmospheric pressure low temperature plasma acts on the gas to be treated, such as air, nitrogen, oxygen, carbon dioxide, etc., which is supplied into the dielectric tube 21 through the pipeline 60 from the gas supply device 50, and generates, as is well known, for example, singlet oxygen ( １ O ２ ), ozone (O ３ ), hydroxyl radical (OH), superoxide anion radical (O ２ -), hydroperoxy radical (HO ２ ), hydrogen peroxide (H ２ O ２) are generated. The gas containing these active species is ejected as a plasma jet from the opening of the dielectric tube 21 that protrudes from the exterior part 12 at one end of the plasma generating device 10. The length of the plasma jet PJ depends on the voltage applied between the electrodes, the flow rate of the gas to be treated determined by the pump 40, etc., but typically, a plasma jet PJ with a length of about 5 mm can be obtained from the opening of the dielectric tube 21. By bringing this plasma jet PJ into contact with the skin on the surface of the human body, it is possible to obtain effects such as sterilizing the skin surface, decomposing and removing waste products and the like adhering to the skin, and activating skin cells.

[0025] 3, a distance L is secured by a conduit 40b between the electrode terminal 23b of the plasma generator 10 and the opening of the dielectric tube 21 from which the plasma jet PJ is ejected. This distance prevents unexpected events such as electrical leakage from the electrodes of the plasma generator 10 to the human body, ensuring the safety of the atmospheric pressure plasma apparatus 1. The distance L may be determined based on the specifications of the high voltage applied to the electrode terminals 23a, 23b of the plasma generator 10, and is, for example, 11 mm as the spatial insulation distance assuming an impulse withstand voltage of 10 kV (see "JIS C 60664-1:2009 Insulation Coordination of Equipment in Low-Voltage Systems - Part 1").

[0026] <Power Supply Device> The power supply device 30 has the function of applying a high voltage between the first electrode 22a and the second electrode 22b of the plasma generation device 10. In this embodiment, the power supply device 30 includes a power conversion device that converts a commercial AC 100V, 50 / 60 Hz power supply into a high voltage to be applied between the electrodes. The power conversion device may include, for example, a transformer, an AC / DC converter, or a combination of an AC / DC converter and a DC / AC inverter, and is capable of applying a DC or AC high voltage between the first electrode 22a and the second electrode 22b. Any step-up or switching circuit may be used to generate the high voltage. As an example, the power supply device 30 is configured to apply an appropriate high voltage between the first electrode 22a and the second electrode 22b. Specifically, the output voltage may be adjusted according to parameters such as the distance between the electrodes, the material, planar dimensions, and thickness of the electrodes. The frequency of the applied AC voltage may also be determined appropriately. The voltage waveform may also be an appropriate waveform, such as a sine wave or a square wave. For example, when the atmospheric pressure low-temperature plasma device 1 of this embodiment is applied to facial skin, if air is used as the gas for plasma treatment, a pulse wave with a frequency of 50 Hz and AC 10 kV can be suitably used in the electrode configuration exemplified above.

[0027] According to the embodiment of the present invention described above, various active species can be generated by contacting atmospheric pressure low-temperature plasma with different types of gases or a mixture of two or more of these gases. Then, by contacting the plasma jet PJ containing these active species with the skin on the surface of the human body, effects such as sterilization of the skin surface, decomposition and removal of waste products adhering to the skin, and activation of skin cells can be achieved. The atmospheric pressure low-temperature plasma used is low-temperature, so there is no risk of burns.

[0028] Furthermore, since the plasma generating unit 20 employs a double helix structure combining the helical first electrode 22a and second electrode 22b, the current flowing through the human body to which atmospheric pressure low-temperature plasma is applied can be minimized. Furthermore, a predetermined distance for insulation according to the applied voltage between the electrodes is secured between the electrode terminal 23b of the plasma generating device 10 and the opening of the dielectric tube 21 from which the plasma jet PJ is ejected. This prevents unexpected situations such as electric leakage from the electrodes of the plasma generating device 10 to the human body, and ensures the safety of the atmospheric pressure plasma device 1.

[0029] <Modification> Next, a modification of the embodiment of the present invention described above will be described. This modification has a configuration in which a syringe needle is provided in the plasma generation device 10 of the embodiment described above. Fig. 5 shows a side view illustrating an example of the configuration of this modification.

[0030] In the previous embodiment, the atmospheric pressure low-temperature plasma generated in the plasma generating unit 20 included in the plasma generating device 10 is emitted from the opening of the dielectric tube 21 to form the plasma jet PJ. This plasma jet PJ acts on skin cells by directly irradiating the skin on the surface of the human body.

[0031] On the other hand, by applying atmospheric pressure low-temperature plasma to all subcutaneous tissues, such as the articular cells that make up the knee joint, it is expected to have the effect of promoting wound repair and suppressing inflammation, and by injecting it into the corpus cavernosum of the penis, it is possible to treat erectile dysfunction, etc. However, with the configuration of the above embodiment, it was not possible to introduce and apply atmospheric pressure low-temperature plasma to such subcutaneous tissues.

[0032] Therefore, in this modification, an injection needle 25 is provided at the tip opening of the dielectric tube 21 in the above embodiment. The injection needle 25 consists of a needle tube 25a and a needle hub 25b, and the needle hub 25b is tightly fitted into the end of the dielectric tube 21. The injection needle 25 can be selected from commercially available products depending on the application. For example, when the purpose is treatment within the knee joint, the outer diameter of the needle tube 25a can be suitably selected to be 0.7 mm (22 gauge). In this way, the injection needle 25 attached to the end of the dielectric tube 21 can be appropriately selected depending on the application and the location of application. As shown in FIG. 5 , atmospheric pressure low-temperature plasma generated within the dielectric tube 21 is ejected as a plasma jet PJ from the tip of the needle tube 25a of the injection needle 25, and various active species can be delivered to subcutaneous tissue, such as inside the joint.

[0033] Thus, according to the modified example of this embodiment, plasma treatment of subcutaneous tissue is possible, which was not possible in the above embodiment.

[0034] The technical scope of the present invention is not limited to the above-described embodiment, and other modifications, applications, etc. are also included within the scope of the claims.

[0035] REFERENCE SIGNS LIST 1 atmospheric pressure low-temperature plasma device 20 plasma generation unit 21 dielectric tube 22a first electrode 22b second electrode 25 syringe needle 30 power supply device 40 pump 50 gas supply device

Claims

1. An atmospheric pressure low-temperature plasma device suitable for the human body, comprising: an atmospheric pressure low-temperature plasma generating unit comprising a first electrode and a second electrode, which are strip-shaped electrodes arranged spirally around a cylindrical dielectric tube forming a gas flow path, and which combines these to form a double-spiral plasma generating electrode pair; a cylindrical exterior part arranged to cover a current-carrying part including the plasma generating electrode pair so as to be able to hold the dielectric tube of the atmospheric pressure low-temperature plasma generating unit; a power supply part connected between the first electrode and the second electrode to supply AC current to the plasma generating electrode pair; and a gas supply part that supplies a gas to be plasma-treated from one end of the dielectric tube into the dielectric tube, and which emits a plasma jet containing gas treated by the atmospheric pressure low-temperature plasma generated inside the dielectric tube from the other end of the dielectric tube protruding from the exterior part.

2. The atmospheric pressure low-temperature plasma device suitable for the human body according to claim 1, wherein the gas supply unit is configured to be able to supply two or more types of gases to be plasma treated.

3. An atmospheric pressure low-temperature plasma device suitable for the human body as described in claim 1 or 2, wherein the other end of the dielectric tube, which is the plasma jet outlet, and the end of the plasma generating electrode pair are configured to be at least 11 mm apart.

4. An atmospheric pressure low-temperature plasma device suitable for the human body according to claim 1 or 2, wherein a syringe needle is provided at the other end of the dielectric tube, which is the plasma jet outlet.

5. An atmospheric pressure low-temperature plasma device suitable for the human body as described in claim 4, wherein the needle base end of the needle tube of the injection needle and the end of the plasma generating electrode pair are configured to be at least 11 mm apart.

6. A method for generating an atmospheric pressure low-temperature plasma jet that is suitable for the human body, comprising: forming a double-spiral plasma generating electrode pair by combining a first electrode and a second electrode, which are strip-shaped electrodes each spirally arranged around a cylindrical dielectric tube that forms a flow path for the gas to be treated; supplying an AC current between the first electrode and the second electrode of the plasma generating electrode pair; supplying the gas to be plasma-treated into the dielectric tube from one end of the dielectric tube; and releasing a plasma jet containing the gas treated by the atmospheric pressure low-temperature plasma generated in the dielectric tube from the other end of the dielectric tube that protrudes from the exterior part.

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