JP2015195162A - Electrode for generating low voltage plasma and plasma radiation method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode for generating low voltage plasma and a plasma radiation method using the same, capable of performing plasma irradiation that is gentle to human skin by preventing a cell membrane from being broken.SOLUTION: An electrode for generating low voltage plasma 10 includes: a base 11 composed of a ferroelectric resin film; a plurality of first electrodes 12 laminated on a front side thereof; a second electrode 13 laminated on the opposite rear side; protective layers 14, 15 on either one of the upper and lower surfaces or on both surfaces. The base 11 is formed by using a resin film having a dielectric constant of 3 to 110.

Description

The present invention relates to a low voltage plasma generation electrode based on a resin film having a dielectric constant of 3 to 110, and a plasma irradiation method using the low voltage plasma generation electrode.

Plasma is used for sterilization of air or the like. In recent years, research on plasma medicine has become active both at home and abroad. At the center of this is to irradiate the affected area directly with the active species and charged particles generated by the plasma jet for hemostasis, tumor treatment, and wound treatment.
Non-thermal effects of discharge plasmas such as active plasma particles (electrons, ions, radicals, other chemically active species), UV, etc. are often beneficial, for example, disinfection of biological tissues, sterilization, skin disease treatment, blood coagulation, etc. is there. The closer the active plasma is to the living tissue, the higher the electric field in the plasma, the higher the intensity and efficacy of the non-thermal plasma treatment.
As the plasma generated in the atmospheric pressure, usually, a dielectric barrier discharge (hereinafter referred to as DBD) using a high voltage is often used. In this DBD, the normal temperature rise is only a few degrees higher than room temperature. DBD is an alternating voltage discharge between two electrodes, at least one of which is typically coated with a dielectric.
DBD plasma is formed between one electrode and a dielectric, known as the discharge gap, and is driven by applying an alternating high voltage (typically 5 kilovolts or more) that generates a strong electric field between the electrodes.
As a treatment method using such DBD plasma, there are the following patent documents. Patent Document 1 describes a method of non-thermally treating human or animal tissue using high-voltage plasma discharge, which promotes blood clotting, sterilization, inactivation of bacteria and fungi, ulcers and wounds Application to treatment of tissue, treatment of tissue disorders and diseases, tissue rejoining and sealing, etc. are described, and it is written that damage is reduced by limiting the current value. That is, paragraph 0029 states that the ability to limit the discharge current to, for example, less than about 50 milliamps, and optionally less than 1 milliamp, reduces the risk of damage to surrounding tissue or nervous system.

Special table 2008-539007 gazette

However, the method of non-thermally applying the gas plasma to the living tissue described in Patent Document 1 is a method of controlling the plasma non-thermally, but the non-thermal plasma discharge is a high-voltage discharge, Is 2-50 kV, optionally 10-50 kV, and the value of the electric field near the surface of the biological tissue may exceed 200 V / mm at the moment of the maximum current, and selectively near the surface of the biological tissue. There is a description that the electric field value may exceed 500 V / mm at the moment of maximum current (paragraph 0029).
In the plasma generated by such a high voltage, the bulk gas temperature is slightly higher than room temperature, but it is clear that the surface potential of the target living body (human body) reaches several hundred volts due to the accumulation of charged particles. ing. This may cause unnecessary cell membrane disruption and DNA mutation. Therefore, it is problematic to irradiate the human body directly.
Therefore, in the present invention, the plasma generating electrode using a ferroelectric resin film that can generate plasma at a lower pressure at atmospheric pressure than in the prior art prevents the cell membrane from being destroyed and is applied to the human skin. An object of the present invention is to provide a plasma generating electrode and a plasma irradiation method capable of performing easy plasma irradiation.

(1) The low voltage plasma generating electrode of the present invention comprises a base composed of a ferroelectric resin film, a plurality of first electrodes on the front side, and a second electrode on the opposite back side, A plasma electrode having a protective layer on one or both of the upper and lower surfaces, wherein the base is a resin film having a dielectric constant of 3 to 110.
(2) The low-voltage plasma generation electrode of the present invention is characterized in that, in the above (1), a plurality of sets of plasma generation electrodes including the first electrode and the second electrode are arranged on the base. And
(3) The low voltage plasma generation electrode of the present invention is the above (1) or (2), wherein a plurality of plasma generation electrodes arranged on the base form an induced flow, and the induced flow is vertically and horizontally It is controllable.
(4) The low voltage plasma generating electrode of the present invention is characterized in that, in the above (3), the induced flow contains fine particles.
(5) The low-voltage plasma generation electrode of the present invention is the above-described (1) to (4), wherein the plasma generation electrode disposed on the base is a vortex type, and an induced flow is generated on the vortex type electrode. The induced flow is formed and can be controlled in the vertical and horizontal directions.
(6) The method of irradiating the low-voltage plasma of the present invention comprises a base composed of a ferroelectric resin film, a first electrode on the front side, and a second electrode on the opposite back side. A plasma electrode having a protective layer on one or both of its lower surfaces, wherein the base is a low-voltage plasma generating electrode using a resin film having a dielectric constant of 3 to 110, and at atmospheric pressure. It is characterized by irradiating the skin with low voltage plasma.

According to the present invention, the skin of a human body can be prevented from being destroyed by DBD by a plasma generating electrode using a ferroelectric resin film capable of generating atmospheric pressure plasma at a lower potential than before. Easy plasma irradiation.

It is a top view of the electrode for plasma generation used for the evaluation test of the electrode for plasma generation concerning the embodiment of the present invention. It is a graph which shows the relationship between a negative ion and the discharge voltage in the result of an evaluation test. It is a graph which shows the relationship between a negative ion and discharge voltage in case dielectric constant (epsilon) = 3 and the thickness of a base is 25 micrometers and 60 micrometers. It is a graph which shows the relationship between the negative ion and discharge voltage which the thickness of a base exerts in the result of an evaluation test. BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic of the atmospheric pressure plasma irradiation apparatus incorporating the electrode for low voltage plasma generation used in Example 1, (a) is a whole system figure, (b) is a plasma irradiation part, (c) is low voltage plasma production | generation. It is a graph which shows the time-dependent fluctuation | variation of the voltage and current in the electrode for operation. It is the schematic which shows the structure of the electrode for low voltage plasma generation used by evaluation of Example 1, (a) is a top view, (b) is a partial expanded longitudinal cross-sectional view. It is the schematic which showed the method for measuring the influence of the plasma irradiation on the percutaneous absorption effect of the rat skin and pig skin used as simulation skin. It is a graph which shows the percutaneous absorption effect used by evaluation of Example 1, (a) is an example of the plasma irradiation to a rat skin, (b) is an example of the plasma irradiation to a pig skin. (A) is a schematic explanatory view of chemical substance permeability to simulated skin when plasma irradiation to the skin is explained, and active species are generated by plasma generation, and the stratum corneum of the skin is reversibly destroyed by the active species. FIG. (B) is an explanatory diagram that focuses on the stratum corneum of the skin and that the lipid bilayer relaxes due to plasma irradiation, and the chemical substance permeation pathway increases. FIG. 10 is a schematic explanatory view showing peaks before and after microplasma irradiation to the pigskin stratum corneum by ATR-FTIR. It is a schematic explanatory drawing of the plasma actuator which controls the flow direction of gas, (a) is SDBD-PA with a large horizontal velocity component, (b) is explanatory drawing of PSJA with a large vertical velocity component. 6 is a cross-sectional configuration example of a plasma actuator using the plasma generation electrode of Example 3. It is the top view (a) of the multielectrode microplasma actuator used in Example 3, and a cross-sectional block diagram (b). 6 is a drive circuit diagram of a microplasma actuator used in Example 3. FIG. It is the light emission photograph of the air produced with the electrode for plasma generation when the drive circuit diagram of FIG. 14 is used. It is the visualization and measurement apparatus of the air flow generated by the microplasma actuator used in Example 3. It is the discharge voltage waveform applied to one HV electrode of a microplasma actuator, and the discharge current waveform corresponding to it. It is a Lissajous figure for estimating the power consumption corresponding to the conditions of FIG. It is explanatory drawing of the flow of the gas induced when a sine wave high voltage is applied to the microplasma actuator of Example 3. FIG. It is explanatory drawing which shows the result of having visualized the gas flow of FIG. It is explanatory drawing which shows the velocity vector in a height direction about FIG. It is explanatory drawing of the flow of the gas opposite to FIG. It is explanatory drawing which shows the result of having visualized the flow of the gas of FIG. It is explanatory drawing which shows the velocity vector in a height direction about FIG. It is explanatory drawing which generates the flow of upward gas using the microplasma actuator of Example 3. FIG. It is explanatory drawing which shows the result of having visualized the upward gas flow of FIG. It is explanatory drawing which shows the velocity vector in a height direction about FIG. It is explanatory drawing which generates the flow of the downward gas using the microplasma actuator of Example 3. FIG. It is explanatory drawing which shows the result of having visualized the flow of the downward gas of FIG. It is explanatory drawing which shows the velocity vector in a height direction about FIG. It is a graph which shows the transient characteristic of the flow induced using the microplasma actuator of Example 3. The measurement point of the transient characteristic of FIG. 31 is shown. FIG. 10 is a schematic explanatory view showing a deformation pattern of an electrode of Example 3. The result of having calculated the voltage of a material part and an electrostatic capacitance when changing the dielectric constant (epsilon) x and thickness tx of the base 11 of the electrode used in Example 3 is shown. This shows the control of fine particles during plasma generation. This shows the difference in fine particle control depending on the applied voltage during plasma generation. FIG. 34 shows the distribution of SiO 2 powder after plasma is generated after SiO 2 having a particle diameter of 50 μm is sprayed on the surface of the spiral electrode shown in FIG. FIG. 34 shows the distribution of SiO 2 powder after plasma generation after SiO 2 having a particle diameter of 50 μm is sprayed on the surface of the meandering electrode shown in FIG. FIG. 34 shows the distribution of salad oil after plasma generation after applying salad oil to the surface of the spiral electrode shown in FIG. FIG. 34 shows the distribution of salad oil after plasma generation after applying salad oil to the surface of the meandering electrode shown in FIG. It is the schematic diagram which showed an example of the arrangement | positioning figure which controls the microparticles | fine-particles on an electrode effectively by arrange | positioning multiple electrode deformation patterns (spiral type plasma generation electrode) shown in FIG.

The low-voltage plasma generating electrode of the present invention supplies a source gas for plasma generation between the plasma generating electrodes, generates plasma in the source gas flow, and irradiates the generated plasma-ized gas to the skin. It is configured. For this, it is preferable to use a very dense local microplasma. This is because “skin pain” is caused by the current flowing from the high voltage to the skin surface through the conductive plasma.
Hereinafter, the plasma generating electrode according to the embodiment of the present invention will be described in detail.
An electrode for plasma generation according to an embodiment of the present invention is formed by laminating a base made of a ferroelectric resin film, a first electrode on the front side, and a second electrode on the opposite back side. It is.

<Base>
The base material as a base on which the first electrode and the second electrode are formed may be a ferroelectric material. For example, polyimide (PI), polyester, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), Teflon (registered trademark) ), Polyethylene (PE), polystyrene (PS) and other resin films Resin films are preferred because they are flexible. Further, fiber cloth, paper, flexible ceramics, and the like are also applicable.
The thickness of the base is not specified, but it needs to be thick enough to withstand dielectric breakdown during plasma generation.

<Dielectric constant>
In the present invention, the dielectric constant ε of the base material is preferably 3 to 110. The reason for this will be described later. As a result, plasma can be generated at a low voltage of 2 kilovolts or less, and the human body surface potential does not reach a voltage for passing a current, and as a result, stimulation of the skin by the current is suppressed.
In addition, it is thought that the magnitude | size of an electric current influences the irritation | stimulation to human body skin rather than the magnitude | size of a voltage, and an electric current does not flow in 2 kilovolts from the surface resistance of skin.
Further, since the plasma is irradiated in a non-contact manner even when the driving voltage is 2 kilovolts, the surface potential of the skin is considered to be several tens of volts, which is lower than the numerical value (2 kilovolts).
In addition, by using a ferroelectric resin film as the electrode, plasma can be generated at a very low cost and at a low voltage, and there is little electromagnetic adverse effect on the target living body and it is safe.

<First electrode, second electrode>
The planar patterns as the first electrode and the second electrode are not particularly limited, and can be determined as appropriate depending on the type, lifetime, and generation amount of active species. For example, the planar pattern of the electrodes can be circular or rectangular. Moreover, it can also be set as a comb-tooth shape or an island shape.
Moreover, the material of the first electrode and the second electrode is not particularly limited, and any material having a predetermined conductivity can be used. For example, aluminum, carbon, copper, silver, iron, tungsten, molybdenum, manganese, titanium, chromium, zirconium, nickel, platinum, palladium, or an alloy thereof can be given. Conductive polymers, carbon nanotubes, and the like can also be used depending on the application. Furthermore, transparent electrodes such as ITO and IZO can also be applied.

The first electrode and the second electrode can form a pattern by, for example, etching a metal foil laminated on a resin film as a base.
The pattern can also be formed by applying a paste on the base resin film. As the coating treatment in this case, any method such as screen printing, calendar roll printing, dipping, vapor deposition, physical vapor deposition, etc. can be used.
When the electrode pattern is applied by a coating method such as screen printing, the above-mentioned various metal or alloy powders are mixed with an organic binder and a solvent (such as terpineol) to produce a conductor paste, and then this conductor paste is placed on the base. It is formed by coating and drying.

In addition, when the planar pattern of the electrodes is comb-like or island-like, DBD occurs at the edges of each comb-tooth portion and island portion, so the pitch of each comb-tooth portion and island portion must be changed. Thus, the pitch of the DBD portion can be changed as appropriate.

<Front protective layer, back protective layer>
The surfaces of the first electrode and the second electrode are preferably covered and protected by a front protective layer and a back protective layer made of a dielectric, respectively. As the protective layer, the dielectric material used as the base material can be used.
Moreover, not only the base material but also organic materials such as epoxy, acrylic, polyamine, acrylic silicon, urethane, lacquer clear, etc. can be applied as a front protective layer or a back protective layer if the film thickness is 10 μm or more. it can.
The front protective layer and the back protective layer can be covered by coating these dielectric material powders on a resin film in which the second electrode and the first electrode are formed in the form of a paste. The second electrode can be protected.
The front protective layer and the back protective layer should be plasma generating electrodes that can generate plasma even in a humid atmosphere by protecting the first electrode and the second electrode, and have excellent moisture resistance and weather resistance. Can do.
The front protective layer and the back protective layer preferably have a thickness of about 5 to 100 μm from the viewpoint of the flexibility of the plasma generating electrode. Although it is possible to make it thicker than that, it is not desirable because it may hinder an increase in applied voltage and flexibility.
In addition, the phosphor material can be made to emit light by plasma by mixing the phosphor material in the protective layer.

<Through hole>
In the present embodiment, the presence or absence of the through hole is not specified. In addition, in the preferred embodiment, after forming the first electrode and the second electrode on the base, the base is subjected to laser processing, ultrasonic processing, cutting processing, press punching method, etc. Through holes can be formed.
Further, the arrangement density and arrangement pattern of the through holes are not particularly limited. For example, in consideration of the lifetime of the activation gas and the processing amount of the object to be processed, the through hole can be provided only on the inlet side (upstream side) of the apparatus, or can be provided over the entire surface of the base.

The arrangement density (number) of through-holes and the size of the through-holes depend on the reaction rate to the object to be treated (skin), the amount (area) of the object to be treated (skin), or depending on the use situation. Density and number can be determined. In a preferred embodiment, a DBD is generated along the base surface at the edge portion of the first electrode.
When the DBD is generated along the base surface in this way, the distance between the plasma generation point and the object to be processed can be minimized, so that the processing efficiency is further increased.

The planar shape of the through hole is not limited and can be changed according to the material and form of the object to be processed and the type of active species. For example, the planar shape of the through hole may be a circle, an ellipse, a triangle, a rectangle, a polygon such as a hexagon, an elongated slit, or the like.

The gas introduced from the through hole is appropriately determined depending on the intended treatment or reaction. One kind of gas may be used, or a plurality of kinds of gases may be supplied from the through holes.
In addition, when one kind of gas is supplied from the through hole, it may be a pure gas or a mixed gas.
Moreover, although the gas supplied from the through hole can be converted into plasma by the action of DBD, a plurality of kinds of gases supplied from the through hole can be reacted with each other under the action of DBD to generate active species. .

The type of gas introduced from the through hole is not limited, and examples include noble gases (such as helium, argon, and neon), nitrogen gas, oxygen gas, hydrogen, and air (atmosphere).
In addition, a liquid such as hydrogen peroxide, peracetic acid, ethanol, methanol, water, or the like is sprayed or evaporated to form a mist (in this embodiment, it may be referred to as a mist liquid, and gas and mist liquid Are collectively referred to as gas).
Moreover, gas (oxygen and hydrogen) generated by electrolysis can also be used.

Further, the gas or mist liquid is usually supplied from the first electrode in the second electrode direction (through the through-hole), but is not limited thereto, and can be supplied along the first electrode, for example ( Such as when there is no through hole).
In addition, the gas pressure can be normally set near atmospheric pressure, and the supply flow rate of the original gas can be controlled by a mass flow meter or the like.

<Control of gas flow direction>
There are the following methods for controlling the direction of gas flow. That is, active control of plasma actuator with semiconductor switching by semiconductor switching.
There are two typical plasma actuators, SDBD-PA with a large horizontal velocity component as shown in FIG. 11A and PSJA with a large vertical velocity component as shown in FIG.
Whether the flow in the horizontal direction or the vertical direction becomes dominant depends on the electrode structure, and two kinds of flows can be selectively generated after the construction of the electrode.
For example, active control of the induced flow direction of the plasma actuator can be performed by selectively driving each electrode of the plasma actuator having three electrodes shown in FIG. 1 by semiconductor switching.
As shown in the figure, when only the left electrode or the right electrode is driven, the operation is the same as that of SDBD-PA, and when both electrodes are driven, the PSJA can be operated.
In addition, by adopting an electrode pattern as shown in FIG. 11 (d), it is possible to drive the electrodes of a plurality of lines and to accelerate the ion wind speed, and to greatly increase the wind speed of the generated ions as compared with one row of electrodes. can do.

<Low voltage processing>
The applied voltage to the plasma generating electrode in the present invention is preferably set to a low voltage of 200 V to 2000 V as the plasma generating electrode applied voltage in order to eliminate irritation of human skin.
If the applied voltage is less than 200V, it may be difficult to generate sufficient DBD on the electrode surface depending on the gas conditions. On the other hand, if it exceeds 2000V, irritation to human skin increases, which is not preferable. Skin is a generic term that includes the epidermis, dermis, hair, subcutaneous adipose tissue, and other accessory organs (cell tissue related to hair growth, pigment-producing cells, etc.).
In order to apply the plasma generating electrode of the present invention to cosmetics, it is desirable to make the electrode disposable for each treatment, and it is possible to print at low cost if it is an electrode formed of a resin film. Unlike conventional plasma generating electrodes, it is disposable and considers hygiene.

In addition, it is expected to promote the percutaneous absorption effect of the drug after irradiating the skin with plasma. Specifically, the following are considered to be targets.
For example, a drug having a molecular weight of 500 or more (specifically, a peptide vaccine) or a drug having low fat solubility (specifically, water-soluble vitamins). When directly irradiating the skin or the like, it is considered that the percutaneous absorption effect of various drugs is improved by combining with drugs in addition to the effect of plasma.

Next, the results of evaluating the concentration of negative ions generated using the low-voltage plasma generation electrode of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view of a plasma generation electrode used in an evaluation test of the plasma generation electrode according to the embodiment.
FIG. 2 is a graph showing the relationship between negative ions and discharge voltage when the dielectric constant is changed in the result of the evaluation test.
FIG. 3 is a graph showing the relationship between the negative ions and the discharge voltage exerted by the thickness of the base when the dielectric constant ε = 3, as a result of the evaluation test.
FIG. 4 is a graph showing the relationship between negative ions and discharge voltage when the thickness of the base is changed in the case of permittivity ε = 40 and 110.

As shown in FIG. 1, the electrode 10 for plasma generation used for the evaluation test has a polyimide film as a first electrode 12 on the front side of the base and a second electrode 13 on the back side, and an aluminum foil having a width of 5 mm via an adhesive. Each was laminated.
The aluminum foil was arrange | positioned so that a 1 mm overlap part might be formed in planar view by the front side and a back side. The base 11 used for the plasma generating electrode has a thickness of 60 μm and has a dielectric constant ε of 3, 40 and 110.
The applied voltage was a sine wave of 27 kHz, and the ion concentration meter was placed at a position 1 cm from the plasma generating electrode.

As shown in FIG. 2, it can be seen that as the discharge voltage is gradually increased, the concentration of negative ions generated in the plasma generating electrode also increases. Further, comparing the dielectric constant 110 and the dielectric constant 3, it can be seen that the higher the dielectric constant, the same ion concentration can be maintained even when the discharge voltage is small.
From this result, it can be seen that a base having a high dielectric constant of the material may be used to reduce the discharge voltage. This is presumably because the effective partial discharge voltage is increased because the partial pressure in the dielectric is reduced.

FIG. 3 is a graph showing the results when the dielectric constant ε of the dielectric material used for the base of the plasma generating electrode is 3, and the thickness is 25 μm and 60 μm. As shown in FIG. 3, it can be seen that a thin 25 μm thickness produces a large amount of negative ions at a low voltage.
From the above test results, in order to generate 2000 × 1000 negative ions in 1 cm ³ of air, a dielectric material having a dielectric constant ε of 110 or less and a discharge voltage of 2 kilovolts or less is used. The surface potential is suppressed below the discharge start voltage, and human-friendly treatment can be performed.

FIG. 4 is a graph showing the results of testing the influence of the thickness of the dielectric material used for the base of the plasma generating electrode.
(A) is a case where the dielectric constant ε of the base material is 40 and the thickness is 30 μm and 60 μm,
(B) is the case where the dielectric constant ε of the base material is 110 and the thickness is 58 μm and 84 μm.
As shown in FIG. 4, when (a) and (b) are compared, the applied voltage is 1300 V or less, the dielectric constant ε is 40, and the dielectric constant ε is 110, which affects the thickness of the dielectric material used for the base. It can be seen that 2000 × 1000 negative ions can be generated.

Embodiments of the present invention will be described below with reference to the drawings.
<Example 1>
Using the electrode for generating a low-voltage plasma of the present invention, evaluation was performed when a chemical substance was permeated from simulated skin (percutaneous absorption).
Percutaneous absorption is thought to be promoted by reversible destruction of the stratum corneum barrier property by irradiation of the skin with low-voltage plasma, and the whole body and local medicinal effects are considered.
For example, there is an effect such that a rapid increase in blood concentration is unlikely to occur and the drug effect is sustained.

5A and 5B are schematic views of an atmospheric pressure plasma irradiation apparatus incorporating the low-voltage plasma generation electrode used in Example 1, wherein FIG. 5A is an overall view of the system, FIG. 5B is a plasma irradiation unit, and FIG. It is a graph which shows the time-dependent fluctuation | variation of the voltage and electric current in the electrode for low voltage plasma generation.
As an evaluation condition, a 27.1 kHz AC power source was used as the power source.
The irradiation time was 3 minutes, the gas type and flow rate were argon (5.0 L / min), and the distance from the simulated skin was 1 mm.

6A and 6B are schematic views showing the configuration of the low-voltage plasma generation electrode 10 of Example 1 used in this evaluation, where FIG. 6A is a plan view and FIG. 6B is a partially enlarged longitudinal sectional view.
As shown in FIG. 6, in the low-voltage plasma generating electrode 10, the base 11 is made of a circular polyimide (PI) resin film (thickness 25 μm, dielectric constant: ε = 3 to 4) having a diameter of 32 mm. A first electrode 12 having a predetermined pattern is formed on the surface with an adhesive layer of 25 μm, and a surface protective layer 14 is covered on the upper surface thereof.
As the first electrode 12, a copper foil having a thickness of 18.5 μm and a width of 0.2 mm was used.
Further, a second electrode 13 is formed on the back surface of the base 11 so as to face the first electrode 12, and the surface thereof is covered with a back protective layer 15.
As the second electrode 13, a copper foil having a thickness of 18.5 μm and a width of 1.2 mm was used.
A through hole 16 having a diameter of 2.0 mm for gas circulation was formed so as to penetrate the first electrode 12, the second electrode 13, and the base 11.
The electrode thickness was set to a total thickness of 0.1 mm.
In this way, by arranging the through holes 16, the plasma generated by the DBD (P) in each first electrode 12 is drawn out by the gas supplied from the through holes 16, and the workpiece ( The effect is that the simulated skin) can be irradiated.
Then, DBD is generated along the base surface from the edge of the first electrode 12 toward the through hole 16.
As a result, the gas is converted into plasma by the DBD, and then supplied toward the simulated skin through the through hole 16.
The through hole 16 had an opening ratio of 18% with respect to the base 11 of a circular polyimide (PI) resin film having a diameter of 32 mm.

<Example 2>
Using the low-voltage plasma generation electrode of this embodiment, the chemical substance permeability to the simulated skin was tested. Rat skin and pig skin were used as simulated skin.
Simulated skin was placed on the stage, and atmospheric pressure plasma was irradiated from above.
The test conditions in Example 2 are as follows as shown in Example 1 (shown in FIG. 5B).
Power supply: AC, 27.1 kHz, 0.6 to 0.8 kV
Processing time: 3 minutes Injection gas flow rate: 5.0 L / min Distance between sample and electrode: 1 mm
Injection gas type: Argon

The electrode shown in Example 1 (shown in FIG. 6) was used as the plasma generating electrode.
External shape of electrode plate: 32 mm
Diameter of the through hole formed in the electrode plate: 2.0 mm
Aperture ratio: 18% (area of through hole / area of electrode plate)
Electrode plate thickness: 0.1 mm
Upper electrode width: 0.2 mm
Lower electrode width: 1.2 mm
Base: Polyimide (PI) resin film having dielectric constant ε3-4 The electrode pattern of the plasma generating electrode was prepared by etching a copper-clad laminate for a flexible material printed wiring board manufactured by Nikkan Kogyo Co., Ltd.
Protective layer: The material was polyimide (PI), thickness: 25 μm, and was coated on the electrode through an adhesive layer having a thickness of 25 μm.
The total thickness of the plasma generating electrode was 100 μm.

FIG. 7 is a schematic view showing a method for measuring the influence of plasma irradiation on the transdermal absorption effect of rat skin and pig skin used as simulated skin.
FIG. 8 is a graph in which the influence of plasma irradiation on the percutaneous absorption effect of the rat skin and pig skin used as simulated skin is measured by the measurement method of FIG. 7, and (a) shows the plasma irradiation on the rat skin. It is an example and (b) is an example of plasma irradiation to a pig skin.
As shown in FIGS. 8A and 8B, the percutaneous absorption effect was observed when the plasma irradiation was performed for 3 minutes as compared with the case where the plasma was not irradiated.
In the present invention, the reason why the plasma irradiation to the skin has an effect on the chemical substance permeability to the simulated skin is that, as shown in FIG. When the layer is reversibly broken and attention is paid to the stratum corneum of the skin as shown in FIG. 9 (b), the space between the lipid bilayers is loosened by the plasma irradiation, and the chemical permeation pathway is increased. And since the gap formed by irradiation is reversible, it is considered that it returns to its original state after a certain time.

FIG. 10 is a schematic explanatory diagram showing peaks before and after microplasma irradiation on the pigskin stratum corneum by ATR-FTIR.
As shown in FIG. 10, the peak reduction before and after microplasma irradiation to the pigskin stratum corneum by ATR-FTIR was also confirmed.
In addition, 2850 cm ⁻¹ indicates CH ₂ ≈lipid, and 2940 cm ⁻¹ indicates CH ₃ ≈protein. These indicate keratin in the pigskin horny layer, and are irradiated with microplasma (each irradiation time is 3 minutes and 10 minutes). ) Shows a decrease in keratin ≒ a decrease in barrier function.
That is, it shows improvement in the permeability of chemical substances such as drugs by the microplasma irradiation shown in FIGS. 8 (a) and 8 (b).

<Example 3>
Next, an example of a plasma actuator using the plasma generating electrode of the present invention will be described below.
FIG. 12 shows a plasma actuator using dielectric barrier discharge. Two electrodes are placed across a dielectric. When the lower electrode is grounded and an AC high voltage is applied to the upper electrode, plasma is generated from the upper electrode toward the lower electrode, and a horizontal gas flow along the wall surface as indicated by an arrow occurs. The driving principle of the plasma actuator is that charged particles in plasma generated by a high electric field are accelerated by Coulomb force, collide with neutral particles, and transmit momentum, thereby generating a macro gas flow.
Conventionally, most of the mm-scale plasma actuators are driven by a high voltage of 5 kV or higher. Therefore, the phenomenon of gas flow due to the low voltage, μm scale actuator structure has not been fully verified. In this example, the characteristics of a microplasma actuator that can be driven at a low voltage of 1.5 kV or less were evaluated. Furthermore, the plasma electrode can be driven independently, and the flow direction induced by the microplasma can be actively controlled by the input signal. The results are shown below.

The structure of the multi-electrode microplasma actuator constructed in this example is shown in FIG.
Electrodes are arranged on both sides of a 25 μm dielectric film. The lower electrode is grounded and is insulated so that no discharge occurs on the lower side. The upper electrode is composed of four independent electrodes. Also, the x coordinate was set in the horizontal direction and the y coordinate was set in the vertical direction.

FIG. 14 shows a circuit diagram for driving the microplasma actuator. A sine wave high voltage can be selectively generated for the four HV terminals by controlling the input to the four high voltage inverters using a microcomputer. The HV terminal (1-4) of the circuit was connected to the HV electrode (1-4) of the microplasma actuator.

Here, FIGS. 15A to 15D show light emission photographs of air when the microplasma actuator is driven using the circuit of FIG. As shown in FIG. 15, the plasma region can be controlled by selectively driving each HV electrode 1-4.

FIG. 16 shows an experimental apparatus for visualizing and measuring the air flow generated by the microplasma actuator. A microplasma actuator was installed on the z stage, and tracer particles were distributed around it. The tracer particles were incense smoke (submicron particles). The gas flow was visualized by irradiating particles with a 532 nm wavelength Nd YVO4 laser and photographing the scattered light with a high-speed camera (Red lake, Motion Scope M3). The discharge voltage was observed with a high voltage probe (Tektronix, P6105A) and an oscilloscope (Tektronix, TDS2024B), and the discharge current was measured with a current probe (Tektronix, P6021). The power consumption of the multi-electrode microplasma actuator was estimated by a Lissajous figure by measuring the voltage of a 10 nF capacitor connected in series.

FIG. 17 shows a discharge voltage waveform and a corresponding discharge current waveform when a high voltage sine wave having a voltage of 1.3 kV and a frequency of 15 kHz is applied to one HV electrode of the microplasma actuator in the experimental apparatus of FIG. Moreover, in order to estimate the power consumption corresponding to the conditions of FIG. 17, a Lissajous figure is shown in FIG. From the area calculation, the energy consumption for one cycle was 100 μJ. The value was multiplied by a frequency of 15 kHz to obtain a power consumption of 1.5 W. Further, when two HV electrodes were driven, the electric power was doubled to 3W.

<Visualization of gas flow>
The result of visualizing the gas flow induced when a sinusoidal high voltage (voltage 1.3 kV, frequency 15 kHz) is applied to the microplasma actuator is shown below. Since the voltage applied to the microplasma actuator is a sine wave centered at zero, the induced flow in the reverse direction described above does not occur, and the flow from the upper electrode to the lower electrode is as shown in FIG. It is thought to occur. Accordingly, when HV1 and HV3 are driven, a rightward flow is obtained as shown in FIG. Moreover, the result of visualizing the rightward flow is shown in FIG. Air is sucked from a wide range toward the leftmost plasma region, and blowout from the rightmost plasma region to a narrow region near the wall surface occurs. In addition, inhalation and blowing of air were observed in each plasma region in between.

FIG. 21 shows the velocity vector distribution of the rightward flow. The speed was 0.6 m / s at the position of the right end, height 0.5 mm. The result was 1.5 times faster than the speed of 0.4 m / s at the center and height of 0.5 mm. This is thought to be due to the repeated acceleration by suction and blowing in the plasma region. Further, it was found that at the right end and the height of 1 mm, the flow velocity was halved to 0.3 m / s, and at the height of 2 mm, it was attenuated to 0.06 m / s. Therefore, it was found that the gas flow was concentrated within 1 mm near the wall surface.

The suction at the left end of the plasma actuator was a flow rate of 0.08 m / s at a height of 0.5 mm and 0.05 m / s at a height of 2 mm. Although it is as small as about 1/6 compared with the speed of the blowout at the right end, the attenuation in the height direction is moderate, and it can be seen that air is sucked in from a wide range. In the operation of suction and rightward flow, it can be seen that suction is performed at a low speed from a wide area and is blown out at a narrow area near the wall surface at a high speed.

Next, by driving HV2 and HV4, as shown in FIG. 22, a leftward flow opposite to that in FIG. 19 was obtained. The visualized leftward flow is shown in FIG.

FIG. 24 shows the velocity vector distribution of the leftward flow. The speed was 0.6 m / s at the position of the left end, height 0.5 mm.
Because of the symmetry of the electrode structure, the flow was essentially reversed from right to left, and essentially the same flow was obtained.

When HV1 and HV4 are driven, the flow from the left and right collides at the center as shown in FIG. 25, and an upward flow is generated.
FIG. 26 shows the result of visualizing upward flow. Suction to the left and right ends occurred, and upward blowing was observed from the center.

FIG. 27 shows the velocity vector distribution of the upward flow. An upward flow of 0.5 m / s was observed at the center and height of 1 mm. Moreover, even at a height of 2 mm, the flow velocity was 0.4 m / s or more, and it was observed that air was blown away from the wall surface, unlike the left / right flow. And it became clear that the suction from the left and right was about 0.1 m / s, which was about 1/5 slower than the blowing at the center.

When HV2 and HV3 are driven, a flow of air flows from the center to the left and right as shown in FIG. 28, and accordingly, a downward flow occurs at the center. FIG. 29 shows the result of visualizing the downward flow. A blowout from the left and right sides to the outside of the plasma actuator occurred, and downward suction was observed at the center.

FIG. 30 shows the velocity vector distribution of the downward flow.
A downward flow of 0.15 m / s occurred at the center, 1 mm in height. Then, a flow of about 0.3 m / s was generated from the left and right to the outside, resulting in an earlier result than the downward flow. The downward flow at the center is due to the suction of the plasma actuator, and the flow from left to right is due to the discharge. Since the suction of the plasma actuator is in a wide range at low speed and the discharge is in a high speed and narrow region, it was confirmed that the downward flow caused by the suction is slow in principle.

Next, FIG. 31 shows the transient characteristics of the induced flow. The measurement points are as shown in FIG. It became clear that it shifted to a steady state 60-80 ms after driving. Although the electrical signal itself that drives the plasma actuator propagates instantaneously, it is thought that this delay occurred because inertial force and viscous force act on the gas.

In addition, as a deformation pattern of the electrode of Example 3, a circular (a) or square (b) spiral type as shown in FIG. 33 is also conceivable. In each pattern diagram, the top is a plan view and the bottom is an enlarged cross-sectional view.
In such a pattern, an ascending or descending airflow can be formed between the center of the whirling and the periphery of the electrode.
As a result, fine particles existing at an arbitrary position on the surface of the electrode constituting the plasma actuator can be moved to a central part of the vortex and aggregated by the fine particle movement effect by the induced flow.
Note that an electrode composed of a plurality of concentric circles or concentric quadrangles having different diameters has the same effect as the spiral type as shown in FIG.

Further, the voltage and capacitance of the material portion when the relative dielectric constant εx and the thickness tx of the electrode base 11 used in Example 3 were changed were calculated.
As shown in FIG. 34, when a ferroelectric film having a large dielectric constant is used as a base material, the voltage applied to the High-ε material portion is reduced, and the dielectric constant is reduced to 1/5 at 10 or more.
From this measurement result, it can be seen that the execution voltage necessary for plasma generation can be greatly reduced, which contributes to simplification and cost reduction of the plasma generation power supply circuit.
That is, by setting the dielectric constant to 10 or more, the capacitance per unit area can be greatly improved, and by setting the dielectric constant to 20 or more, the dependence of the thickness of the electrode base 11 (film) is hardly seen. .

FIG. 35 shows particle control during plasma generation.
Although 1 μm AL ₂ O ₃ powder (upper) and 50 μm SiO ₂ powder (lower), a decrease in the amount of powder at the plasma generation site (near the line electrode) can be seen during plasma generation.
FIG. 36 shows the difference in particulate control depending on the applied voltage during plasma generation.
The target fine particles are 1 μm WC (tungsten carbide).
The removal of fine particles on the electrode is more noticeable when the pulse voltage is 1.5 kV than when the applied voltage is 1 kV.
FIG. 37 shows the distribution of SiO 2 powder after plasma generation after the SiO 2 particle diameter of 50 μm is sprayed on the surface of the spiral electrode shown in FIG. The movement of fine particles was confirmed in the region where the ground electrode was present.
FIG. 38 shows the distribution of SiO2 powder after plasma generation after the SiO2 particle size of 50 [mu] m is sprayed on the surface of the meandering electrode shown in FIG. As in FIG. 37, the movement of the fine particles in the region where the ground electrode exists was confirmed.
FIG. 39 shows the distribution of salad oil after plasma generation after applying salad oil to the surface of the spiral electrode shown in FIG. Oil movement was confirmed in the area where the ground electrode was present.
FIG. 40 shows the distribution of the salad oil after plasma generation after applying the salad oil to the surface of the meandering electrode shown in FIG. Oil movement was confirmed in the area where the ground electrode was present.
FIG. 41 shows an example of an arrangement diagram in which fine particle control on the electrode group is effectively performed by using an electrode group in which a plurality of electrode deformation patterns (spiral type plasma generation electrodes) shown in FIG. 33 are arranged on the base. It is a schematic diagram shown.

The low voltage plasma generation electrode of the present invention prevents cell membrane destruction due to DBD by the plasma generation electrode using a ferroelectric resin film capable of generating atmospheric pressure plasma at a lower potential than before. This makes it possible to irradiate the human skin with plasma.
In the future, it is expected to be applied to cancer vaccines such as peptides and water-soluble vitamins.
Furthermore, the shape of the plasma electrode can control the induced flow and fine particles during plasma generation, which is highly industrially applicable.

DESCRIPTION OF SYMBOLS 10 Plasma generation electrode 11 Base 12 1st electrode 13 2nd electrode 14 Front protective layer 15 Back protective layer 16 Through-hole P Dielectric barrier discharge (DBD)

Claims (6)

A base composed of a ferroelectric resin film;
A plurality of first electrodes are laminated on the front side, and a second electrode is laminated on the back side on the opposite side,
A plasma electrode having a protective layer on one or both of its upper and lower surfaces,
An electrode for generating low voltage plasma, wherein the base is a resin film having a dielectric constant of 3 to 110. 2. The low-voltage plasma generation electrode according to claim 1, wherein a plurality of sets of plasma generation electrodes including the first electrode and the second electrode are arranged on the base. An induced flow is formed by a plurality of plasma generating electrodes arranged on the base,
3. The low voltage plasma generating electrode according to claim 1, wherein the induced flow can be controlled in the vertical and horizontal directions. The low-voltage plasma generation electrode according to claim 3, wherein the induced flow includes fine particles. The plasma generating electrode disposed on the base is a swirl type,
Forming an induced flow on the spiral electrode;
The low-voltage plasma generation electrode according to any one of claims 1 to 4, wherein the induced flow can be controlled in the vertical and horizontal directions. A base composed of a ferroelectric resin film;
The first electrode is laminated on the front side, and the second electrode is laminated on the back side on the opposite side,
A plasma electrode formed with a protective layer on one or both of its upper and lower surfaces,
The base is a method of applying low voltage plasma to the skin at atmospheric pressure using an electrode for generating low voltage plasma using a resin film having a dielectric constant of 3 to 110.