WO2008146990A1

WO2008146990A1 - Plasma radical sterilization apparatus and method

Info

Publication number: WO2008146990A1
Application number: PCT/KR2007/005057
Authority: WO
Inventors: Sung-Chun Kim; Song-Sun Chang
Original assignee: Sung-Chun Kim; Song-Sun Chang
Priority date: 2007-05-31
Filing date: 2007-10-16
Publication date: 2008-12-04
Also published as: KR100847216B1

Abstract

Provided is a plasma radical sterilization apparatus and method. The apparatus includes a vacuum controller, a flow control vaporizer, a sterilizer spray unit, a high frequency impedance unit, and a sterilization chamber with a plasma region and a sterilization region independently separated. The vacuum controller reduces and controls a pressure and controls the sterilization chamber to a set vacuum state. The flow control vaporizer vaporizes a liquid sterilizer into a gaseous sterilizer and controls an amount of the gaseous sterilizer suppied to the sterilization chamber. The sterilizer spray unit uniformly sprays the gaseous sterilizer under the control of the flow control vaporizer. The high frequency impedance unit provides a high frequency power to the sterilization chamber, generates plasma, and automatically matches an impedance of the sterilization chamber. The sterilization chamber separates radicals through an electrode from plasma and sterilizes a sterilization target using the radicals.

Description

PLASMA RADICAL STERILIZATION APPARATUS AND

METHOD

Technical Field

[1] The present invention relates to sterilization using plasma, and more particularly, to a plasma radical sterilization apparatus and method for generating plasma within a sterilization chamber and concurrently performing a sterilization work using generated radicals, thereby maximizing a sterilization efficiency and performing sterilization without a damage caused by temperature and plasma.

[2]

Background Art

[3] In general, a method for sterilizing medical instruments and medical supplies uses high-temperature, high-pressure steam or Ethylene Oxide (EO) gas. However, the method has many drawbacks of a damage of a sterilization target due to temperature, a long time taken for eliminating residual gas, environmental pollution regulations, etc.

[4] Further, an apparatus for spraying hydrogen peroxide (H O ) to a decompressed chamber and performing sterilization has been developed. However, the apparatus has a disadvantage that it requires repeating a procedure of decompression/ spraying/compression for perfect sterilization and hence requires a long sterilization time, because hydrogen peroxide (H O ) has a limitation in its sterilizing power and infiltration into a sterilization target. Further, the apparatus has a troublesome drawback that it requires subsequent processing of exhaust of residual hydrogen peroxide (H O ) using plasma or other technologies.

[5] To provide a solution to the drawbacks, a diversity of sterilization apparatuses directly using plasma has been developed. The plasma sterilization apparatuses up to now have drawbacks that a conductive target is damaged due to high-voltage arc generation, and plastic type and rubber type targets are irreversibly damaged due to high temperature and high voltage, because a sterilization target is directly positioned in a plasma region.

[6] To prevent the plasma- induced damage to the sterilization target, a plasma generation chamber is installed in front or in rear of a sterilization chamber. However, there are issues of inefficiency due to installation of a separate supplementary chamber and a limitation of a plasma region size, and a problem on sterilization efficiency based on a physical distance from a sterilization target.

[7] Further, in order to go beyond a limitation of sterilization within a plasma region, a method for wetting a sterilization target by previously spraying a sterilizer such as hydrogen peroxide and then exposing the sterilization target to plasma to thereby improve sterilizing power has been developed. However, real circumstances are that vexatious preceding processes of decompression/ sterilizer-spraying/compression/decompression are increased and also a problem caused by exposure to plasma has been unsettled.

[8]

Disclosure of Invention Technical Problem

[9] Accordingly, the present invention is directed to a plasma radical sterilization apparatus and method that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

[10] An object of the present invention is to provide a plasma radical sterilization apparatus and method for generating plasma within one sterilization chamber and con- cucrrently performing a sterilization work using generated radicals, thereby miximizing a sterilization efficiency and sterilizing a sterilization target in one-time process using plasma radicals.

[11] Another object of the present invention is to provide a plasma radical sterilization apparatus and method for simply installing and effectively sterilizing even an elongate sterilization target such as an endoscope hose by installing a union for enabling installation of elongate hoses of a diversity of calibers at a manifold exhaust plate, preventing a sterilization target from being damaged due to direct contact with plasma by independently separating a plasma region from a sterilization region, and effecting a powerful sterilization by vaporizing a liquid state sterilizer, generating plasma, and generating a large amount of radicals from the plasma.

[12]

Technical Solution

[13] To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided a plasma radical sterilization apparatus. The apparatus includes a vacuum controller, a flow control vaporizer, a sterilizer spray unit, a high frequency impedance unit, and a sterilization chamber with a plasma region and a sterilization region independently separated. The vacuum controller reduces and controls a pressure and controls the sterilization chamber to a set vacuum state. The flow control vaporizer vaporizes a liquid sterilizer into a gaseous sterilizer and controls an amount of the gaseous sterilizer suppied to the sterilization chamber. The sterilizer spray unit uniformly sprays the gaseous sterilizer under the control of the flow control vaporizer. The high frequency impedance unit provides a high frequency power to the sterilization chamber, generates plasma, and automatically matches an impedance of the sterilization chamber. The sterilization chamber separates radicals through an electrode from plasma, which is generated by applying a high frequency power of the high frequency impedance unit to a sterilizer sprayed from the sterilizer spray unit, and sterilizes a sterilization target using the radicals, if it is completed to control a vacuum state by the vacuum controller, control an amount of a sterilizer by the flow control vaporizer, and spray the sterilizer by the sterilizer spray unit.

[14] The sterilization chamber may include a plasma unit for controlling generated plasma by installing the sterilizer spray unit spraying gas and serving as an anode and the electrode serving as a cathode.The electrode may have a plurality of vents and passes radicals whose electric property is controlled among the generated plasma.

[15] The sterilization chamber may include a sterilization room for sterilizing a sterilization target by radicals generated from plasma. The sterilizer spray unit may spray a gaseous sterilizer using a shower head in a rectangular- shaped sterilization apparautus. In the shower head, a clamp may be installed outside of the sterilization chamber and move up/down in position and adjust a density of generated plasma.

[16] The shower head may include a plate serving as an anode and having a plurality of holes, a sterilizer supply line for supplying gas to the plate, and the clamp connecting to the supply line and supplying a high frequency power.

[17] The flow control vaporizer may include a vessel supplied with oxygen for carrying a sterilizer and generating plasma, and supplied with the sterilizer, a heater for heating the vessel, a temperature controller for controlling a temperature of the sterilizer within the vessel and controlling vaporization, and a line heater connecting with a supply line for a vaporized sterilizer gas, controlling a temperature of the supply line, and preventing a liquefaction of the sterilizer gas.

[18] In another aspect, there is provided a plasma radical sterilization method. The method includes a first process of decompressing and making a sterilization chamber vacuous by a set value; a second process of putting a sterilizer into the sterilization chamber, uniformly spraying the sterilizer through a sterilizer spray unit, and controlling an amount of the sterilizer and a pressure intensity of the sterilization chamber; a third process of generating and applying a high frequency power to the sterilizer spray unit and an electrode and generating the sterilizer in a plasma state; and a fourth process of carrying only radicals among the plasma to a sterilization room within the sterilization chamber and sterilizing a sterilization target.

[19] The fourth process includes carrying only radicals among the plasma to the sterilization room through a plurality of vents; and horizontally or vertically rotating while sterilizing a sterilization target provided in the sterilization room.

[20] The fourth process includes, upon completion of sterilization of the sterilization target, stopping sterilizer supply and the high frequency power; opening the vacuum valve to the maximum and making the sterilization chamber vacuous; injecting nitrogen (N ) into the sterilization chamber and making the sterilization chamber in an atmospheric pressure state; and taking a sterilization target out of the sterilization chamber. [21]

Advantageous Effects

[22] As described above, a rectangular-shaped or circular- shaped plasma radical steriliztion apparatus of the present invention has an effect of facilitating plasma generation as well as performing efficient radical generation and fast sterilization by a small amount of hydrogen peroxide (H O ), because the plasma radical sterilization apparatuses all use vaporized hydrogen peroxide (H O ) and oxygen (O ).

[23] First, the present invention can perform faster sterilization in a single process

(decompression-plasma radical), not a complex and repeated work of decompression, spraying, compression/heating, decompression, spraying, and compression/heating that has been implemented by a conventional sterilization apparatus.

[24] Second, the present invention can perform fast and efficient sterilization, using OH⁺ and O⁺ radicals having a smaller molecular size and a greater oxidation force than a conventional sterilizer (hydrogen peroxide (H O )).

[25] Third, a conventional sterilizer supply way (spraying) being a physical method had a difficulty in sterilizing sterilization targets a distance between which is small or a sterilization target positioned outside a sprayer region. Unlike this, in the present invention, a gas shower head and a manifold exhaust plate are installed at proper positions and radicals sterilize a sterilization target, getting in uniform contact with the sterilization target, as well as a tray storing the sterilization target is rotated to maximize such an efficiency of sterilization.

[26] Fourth, in the present invention, a plasma region is completely separated from a sterilization region in the same chamber, thereby preventing a sterilization target from being damaged by plasma.

[27] Fifth, the present invention is designed to vary a distance between a gas shower head and a cathode and thus can maintain an optimal distance upon plasma generation depending on a volume or amount of a sterilization target, provides a manifold exhaust plate with several vents having a different size on the basis of a decompression port to maintain a uniform pressure in a sterilization chamber, and efficiently sterilize an elongate hose type (endoscope parts), etc.

[28] Sixth, the present invention does not require a separate device for sterilizing an elongate hose type (endoscope parts), etc. [29] Seventh, unlike a conventional sterilization apparatus, the present invention is simple and convenient in use in that it does not require adding a conventional supplementary process such as after-sterilization sterilizer reprocessing because sterilization is performed using plasma.

[30] Eighth, the present invention completes a sterilization process by positioning a sterilization target in a sterilization chamber and manipulating an operation switch, without a conventional inconvenient and complex process of putting a sterilization target in hydrogen peroxide (H O ) or absorbing hydrogen peroxide (H O ) on a surface of a sterilization target.

[31] Ninth, the present invention has an automatic impedance matching unit for automatically tracing and matching a chamber impedance variation. The automatic impedance matching unit can perform impedance matching, communicating with a sterilization apparatus or independently.

[32] Tenth, the automatic impedance matching unit displays a matching state by graph and digital value in real-time and has a storage unit and a circuit design program as well.

[33] In addition to the above description, the present invention can implement a process of decompression, spraying, compression/heating, decompression, spraying, and compression/heating that has been implemented by a conventional sterilization apparatus and a process of putting a steriliztion target in hydrogen peroxide (H O ) or absorbing hydrogen peroxide (H O ) on a surface of the sterilization target for sterilization. The present invention can properly sterilize a sterilization target in compliance to a usage of the sterilization target, without installing a separate sterilization unit to prevent the sterilization target from being deformed due to high temperature.

[34] The present invention has an effect of monitoring a sterilization status in real-time using a radical analysis unit and when sterilization is not completed within a setting time or when a sterilization work is stopped, notifying a worker of a sterilization result through alarm or other methods, thereby preventing an accident from happening due to incomplete sterilization of a sterilization target.

[35]

Brief Description of the Drawings

[36] FIG. 1 is a schematic diagram illustrating a construction of a plasma radical sterilization apparatus according to an exemplary embodiment of the present invention;

[37] FIG. 2 is a schematic diagram illustrating a construction of a plasma radical sterilization apparatus according to another exemplary embodiment of the present invention; [38] FIG. 3 is a diagram illustrating constructions of a vaporizer and a supply line according to the present invention;

[39] FIG. 4 is a detailed diagram illustrating rectangular and circular shower heads;

[40] FIG. 5 is a diagram illustrating a gas tube of a circular chamber;

[41] FIG. 6 is a diagram illustrating a variable unit for varying a distance between plasma generating electrodes according to the present invention; [42] FIG. 7 is a diagram illustrating an electrode serving as a plasma generating ground electrode while passing radicals generated from plasma according to the present invention; [43] FIG. 8 is a diagram illustrating a rotation unit for horizontally or vertically rotating a tray to increase a sterilization efficiency of a sterilization chamber according to the present invention; [44] FIG. 9 is a diagram illustrating a construction of a manifold exhaust plate for uniform exhaust within a sterilization chamber according to the present invention; [45] FIG. 10 is a diagram illustrating a construction of a manifold exhaust plate for uniform exhaust within a circular sterilization chamber according to the present invention; [46] FIG. 11 is a diagram illustrating a construction of an automatic impedance matcher for performing automatic impedance matching depending on a chamber impedance at the time of plasma generation; [47] FIG. 12 illustrates a real-time graph displaying a matching format and an example of a digital display screen in a plasma radical sterilization apparatus according to the present invention; and [48] FIG. 13 is a flowchart illustrating a plasma radical sterilization method according to the present invention. [49]

Mode for the Invention [50] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to accompanying drawings. [51] It should be noted that a description of only part necessary for understanding operation of the present invention will be made below and a description of other parts will be omitted. [52] A plasma radical sterilization apparatus of the present invention is of a rectangular or circular shape. The rectangular-shaped sterilization apparatus generates radicals from plasma, carries the radicals from top to bottom, and performs a sterilization work by the radicals. [53] In the circular-shaped sterilization apparatus, a plasma unit is installed to surround a sterilization room by 360 degrees and generates plasma. Hence, the circular-shaped sterilization apparatus processes a quick and efficient sterilization because it can acquire much more radicals and plasma potentials than the rectangular-shaped sterilization apparatus.

[54] FIG. 1 is a schematic diagram illustrating a construction of a plasma radical sterilization apparatus according to an exemplary embodiment of the present invention.

[55] Referring to FIG. 1, the plasma radical sterilization apparatus according to the present invention includes a sterilization chamber 10, an automatic flow controller 20, a vaporizer 30, an automatic impedance matcher 40, a high-frequency power supply unit 50, a shower head 60, a plasma unit 70, a sterilization room 80, an electrode 90, a manifold exhaust plate 100, an automatic pressure controller 110, a decompressor 120, a sterilizer supply line unit 130, and a radical analysis unit 140.

[56] The sterilization chamber 10, an airtight chamber, includes the plasma unit 70 for generating plasma and the sterilization room 80 for performing sterilization using radicals. The automatic flow controller 20 automatically controls gas or vaporized H O to a set value.

2

[57] The vaporizer 30 vaporizes a liquid-state H O into gas facilitating plasma generation. The automatic impedance matcher 40 automatically matches an impedance depending on a variation of impedance within the sterilization room.

[58] The high-frequency power supply unit 50 generates and provides a high frequency power supply. The shower head 60 uniformly sprays a vaporized H O while serving as an anode for plasma generation. The plasma unit 70 that is a plasma generation region houses OH⁺ and O⁺ radicals and ions.

[59] The strilization room 80 houses only OH⁺ and O⁺ radicals and processes sterilization.

The electrode 90 has vents for uniformly carrying OH⁺ and O⁺ radicals to the sterilization room 80.

[60] The manifold exhaust plate 100 uniformly discharges reaction residues. The automatic pressure controller 110 automatically controls and opens and closes an opening depending on a set pressure. The decompressor 120 decompresses the sterilization room 80.

[61] Regarding an operation principle of a sterilization apparatus using radicals, oxygen

(O ) and a sterilizer are formed as plasma within the decompressed sterilization chamber 10 by supplying a high frequency power of 13.56 MHz or 27.12 MHz. The vaporized sterilizer is generated as radicals, passing through the shower head serving as an anode.

[62] The generated radicals pass through the plasma source ground electrode 90 and thus, only radicals with no electric property are carried toward an exhaust side, thereby getting in contact or being infiltrated into a sterilization target in the sterilization room 80 and performing sterilization.

[63] If sterilization using radicals according to the present invention is applied, a sterilization target can be prevented from being damaged due to temperature, high frequency power, and plasma since it is exposed only to radicals without direct exposure to plasma, and can be sterilized with a sterilizing power even greater than that of a sterilizer itself by using radicals.

[64] Unlike plasma, radicals have no directionality because the radicals do not have an e lectric property, and are carried along a flow of exhaust gas together with a reactant. Thus, the manifold exhaust plate 100 is installed to increase an exhaust uniformity and enable a sterilization target to get in uniform contact with even more radicals. The radical analysis unit 140 is installed to monitor an amount of generated radicals in realtime, thereby enabling comparison and analysis of sterilization status.

[65] In the rectangular- shaped plasma radical sterilization apparatus according to the present invention, the rotation unit is installed in the sterilization room 80 to rotate a tray putting a sterilization target and process uniform steriliation for a sterilization target during an inflow of radicals from a plasma source through the electrode 90. The rotation unit rotates horizontally or vertically.

[66] Meantime, a conventional sterilization apparatus has a difficulty in effectively sterilizing an interior of an elongate sterilization target with a fine caliber (about 10 mm or less) such as an endoscope hose because of its spray type construction. Unlike this, the present invention installs a fixing union 102 for simply and conveniently installing hoses with diverse sizes (about 1 mm to 50 mm) at the exhaust vents of the manifold exhaust plate 100 and discharges O⁺ and OH⁺ radicals through the interior of the sterilization target. By doing so, the present invention can simply install even the elongate sterilization target with the fine caliber and facilitate sterilization.

[67] In the rectangular- shaped plasma radical sterilization apparatus of FIG. 1 according to the present invention, a sterilization target is positioned in the bottom sterilization room 80 and the manifold exhaust plate 100 is positioned under the sterilization target. Thus, plasma is generated at top and is carried to bottom while the sterilization target is sterilized using radicals generated from the plasma.

[68] Thus, the present invention installs the rotation unit for rotating a target safekeeping box under or in rear of the sterilization chamber 10 to prevent a sterilization target from getting in direct contact with plasma and being damaged by arc, ions or high temperature as in the conventional art and allow radicals to uniformly react with the sterilization target.

[69] Further, the present invention is designed to vary a distance between the gas shower head 60 and the cathode electrode 90 and thus, can control an optimal distance for plasma generation depending on a size or amount of a sterilization target. [70] An operation of the rectangular-shaped sterilization apparatus of FIG. 1 will be described. First, after a sterilization target is put in the sterilization chamber 10, the decompressor 120 comprised of a vacuum pump is activated. Next, by opening the automatic presure controller 110 comprised of a vacuum valve to the maximum, the sterilization chamber 10 is in a vacuum state through the manifold exhaust plate 100.

[71] After that, when the sterilization chamber 10 reaches a target vacuum degree (about

100 mTorr or less), hydrogen peroxide (H O ) gas vaporized by the vaporizer 30 is inputted into the sterilization chamber 10 under the control of the automatic flow controller 20. If so, the gas injected through the shower head 60 is uniformly sprayed.

[72] A combination gas of O and H O injected using the automatic flow controller 20 is controlled to about 100 seem to 2000 seem. A pressure within the sterilization chamber 10 is maintained at about 500 mTorr to 2000 mTorr using the automatic pressure controller 110 comprised of the vacuum valve.

[73] The high frequency power supply unit 50 generates a high frequency power between

100 W to 2000 W and applies the generated high frequency power to the shower head 60 serving as an anode and the cathode 90 serving as a cathode.

[74] The automatic impedance matcher 40 matches an impedance such that a high frequency power is applied to both the shower head 60 and the electrode 90 without a loss of a reflected wave.

[75] The high frequency power supplied from the high frequency power supply unit 50 leads to a plasma state of the combination gas of O and H O in the plasma unit 70. r ° 2 2 2 ^r

Plasma contains OH⁺ and O⁺ radicals and ions to be used for sterilization.

[76] Because the electrode 90 serving as a cathode is grounded, the generated plasma is not carried into the sterilization room 80 and only OH⁺ and O⁺ radicals are carried into the sterilization room 80 through the vents of the electrode 90.

[77] The OH⁺ and O⁺ radicals are carried into the sterilization room 80 through the vents of the electrode 90 while sterilizing the sterilization target.

[78] Upon completion of sterilization, a high frequency power supply is switched off and gas is turned off. By opening the automatic pressure controller 110 to the maximum, the sterilization chamber 10 is in a vacuum state (about 100 mTorr or less). By injecting nitrogen (N2) into the sterilization chamber 10, the sterilization chamber 10 is in an atmosperic pressure state. After that, the sterilization target is taken out of the sterilization chamber 10, thereby completing a sterilization work. The sterilization work is automatically performed by one-time setting.

[79] FIG. 2 is a schematic diagram illustrating a construction of a plasma radical sterilization apparatus according to another exemplary embodiment of the present invention.

[80] Unlike the rectangular- shaped plasma radical sterilization apparatus of FIG. 1, a circular-shaped plasma radical sterilization apparatus can generate much more radicals by constructing a whole (up/down, left/right) of a sterilization chamber 10 as an electrode.

[81] Referring to FIG. 2, a circular sterilization room 80 is positioned inside an inner electrode 90, and a plasma unit 70 is installed to surround the circular sterilization room 80 by 360 degrees.

[82] A sterilization target is sterilized in the sterilization room 80 using radicals, independently separated from the plasma unit 70. Hence, a damage caused by plasma, that is, a damage caused by arc, ions or high temperature is prevented.

[83] The plasma unit 70 surrounding an exterior of the sterilization room 80 by 360 degrees is installed to generate plasma in all directions. Hence, the circular- shaped plasma radical sterilization apparatus can acquire much more radicals and plasma potentials than the rectangular-shaped sterilization apparatus and thus, processes a quick and efficient sterilization.

[84] The circular- shaped sterilization apparatus injects gas into a gas tube 65 and generates plasma between the anode 60 surrounding an exterior of the sterilization chamber 10 by 360 degrees and the electrode 90. Among the thus generated plasma, ions or electrons with electric property are extinguished by two electrodes 60 and 90. Alternately, the generated plasma exists only within a plasma unit 70 region, thereby preventing a damage of a sterilization target.

[85] However, radicals with no electric property are carried into the sterilization room 80, passing through vents of the electrode 90 by a vacuum unit using a manifold exhaust plate, and perform a sterilization.

[86] In the rectangular- shaped sterilization apparatus, the shower head 60 serves as an anode and sprays gas. In the circular- shaped sterilization apparatus, the gas tube 65 sprays gas and serves as an anode.

[87] As described above, the present invention separates the sterilization chamber 10 into the plasma unit 70 and the sterilization room 80 and processes steriliation without a damage of a sterilization target.

[88] Unlike the apparatus of FIG. 1, the circular-shaped plasma radical sterilization apparatus of FIG. 2 has an advantage of generating much more radicals by constructing the whole (up/down, left/right) of the sterilization chamber 10 as the electrode.

[89] FIG. 3 illustrates the vaporizer 30 according to the present invention.

[90] The vaporizer 30 transfers a vaporized gas to the sterilization chamber 10 to prevent dew condensation.

[91] The vaporizer 30 includes a vaporizing vessel for vaporizing a liquid-state hydrogen peroxide (H O ) into a gaseous state facilitating plasma generation; and a dew condensation preventer for preventing a vaporized gas from being restored to liquid. The dew-condensation preventer is constructed by attaching a heater 32 (~ 200 ⁰C) to a bottom of the airtight vessel.

[92] Hydrogen peroxide (H O ) is vaporized by putting the hydrogen peroxide (H O ) in the vaporizing vessel, controlling a temperature by the temperature controller 34, and activating the heater 32. Oxygen (O ) is concurrently supplied as a carrier gas so as to facilitate carriage of the vaporized H O gas and plasma generation.

[93] The generated gas is supplied to the shower head 60 of the vaccum chamber 10 through a supply line 36. If the supply line 36 is at a low temperature or room temperature, the vaporized H O gas is again restored to liquid. There can occur a phenomenon of dew condensation at the supply line 36. To provide a solution to such drawbacks, a line heater 38 is used to maintain the gas supply line 36 at a predetermined temperature of about 60 ⁰C to 200 ⁰C, thereby preventing a dew condensation or a restoration to liquid.

[94] FIG. 4 is a detailed diagram illustrating rectangular and circular shower heads.

[95] The shower head connects with a shower head plate 62, the sterilizer supply line unit

130, and the automatic impedance matcher 40.

[96] FIG. 4 illustrates a schematic construction of an electrode type gas shower head 60.

The sterilizer supply line unit 130, an inlet for introducing a vaporized gas, is comprised of a copper pipe having a diameter of about 1/2 inches to 1/4 inches. The automatic impedance matcher 40 connecting to the sterilizer supply line unit 130 is a clamp using an elasticity of a copper plate having a thickness of about 1 mm. The automatic impedance matcher 40 supplies a high frequency power, connecting to the sterilizer supply line unit 130. Thus, the shower head is supplied with a sterilizer and a high freuency power at the same time.

[97] The shower head plate 62 has a total thickness of about 5 mm to 15 mm and is comprised of aluminum having a thickness of about 3 mm to 5 mm. The shower head plate 62 has a hollow interior and has a plurality of holes each having a diameter of about 0.5 mm to 2.0 mm. The holes have an interval of about 3 mm to 15 mm.

[98] The vaporized gas is uniformly sprayed to the fine holes of the shower head plate 62 via the gas introduction inlet. The shower head serves as an electrode by a high frequency power supplied from the impedance matcher 40.

[99] The thus supplied gas simply generates uniform plasma by the shower head 60 and the electrode 90.

[100] The shower head 60 can generate uniform plasma by a simple construction designed to implement high frequency power supply and gas introduction by a single unit.

[101] FIG. 5 illustrates the gas tube 65 of the circular chamber.

[102] The gas tube 65 has a plurality of holes (openings) and sprays gas.

[103] In the circular shaped sterilization apparatus of FIG. 2, the gas tube 65 is used in place of the shower head 60 and serves to spray sterilizer gas.

[104] The shower head 60 is used in the rectangular-shaped sterilization apparatus. The gas tube 65 is used in the circular- shaped sterilization apparatus.

[105] FIG. 6 is a diagram illustrating an electrode variable unit for varying a distance between plasma generating electrodes according to the present invention.

[106] As shown in FIg. 6, the electrode type gas shower head 60 fixes a gas introduction part by a circular clamp 64. If the clamp 64 is undamped and the shower head 60 is adjusted up/down, a distance between both the electrodes, that is, the shower head 60 and the electrode 90 can be adjusted as shown in FIG. 1.

[107] The adjusting of the distance between both the electrodes 60 and 90 is to increase or decrease a plasma density. The plasma density is in an inverse proportion to a square of the distance between both the electrodes. In other words, if the distance decreases, the plasma density is fourth times the decreased distance. When a sterilization target insensitive to temperature is sterilized within a shorter time, a sterilization work is implemented with the inter-electrode distance decreasing and the plasma density increasing.

[108] When a sterilization target sensitive to temperature is sterilized, sterilization is performed at low temperature with the distance between both the electrodes 60 and 90 increasing and the plasma density decreasing.

[109] FIG. 7 illustrates the electrode 90 serving as a plasma generating ground electrode while passing radicals generated from plasma according to the present invention.

[110] The electrode 90 shown in FIG. 7 is an electrode facing the electrode type gas shower head 60 serving as an anode. The electrode 90 processes ions in the plasma region by ground connection and energy loss, thereby preventing ions from being infiltrated into the sterilization room 80 and applying a physical stimulus to the sterilization target.

[I l l] The ground electrode 90 has numerous small vents 92 and hence, radicals with no electric property reach and smoothly sterilize the sterilization target without any interference.

[112] FIG. 8 illustrates a tray for putting and fixing a sterilization target and a rotation unit for horizontally or vertically rotating the tray to increase a sterilization efficiency in the plasma radical sterilization apparatus according to the present invention.

[113] The rotation unit is a solution to a disadvantage in which when sterilization targets are in standing state, a sterilizer is difficult to be infiltrated between the sterilization targets. FIG. 8A shows a rotation unit rotating in a horizontal direction and FIG. 8B shows a rotation unit rotating in a vertical direction.

[114] The rotation unit has a net type tray 82 to prevent a sterilization target from getting out of a sterilization region at the time of rotation. The rotation unit has a locker and transmits a rotary force of a plasma gear motor 84 to the tray 82 through a coupling unit 86, horizontally or vertically rotates the tray by a bearing 88, and rotates the sterilization target within the tray 82, thereby smoothly sterilizing the sterilization target with uniformity.

[115] The vertical, horizontal rotation unit of FIG. 8 is installed to enable sterilization of the sterilization target with more efficiency in the rectangular-shaped sterilization apparatus.

[116] FIG. 9 illustrates a construction of the manifold exhaust plate 100 for uniform exhaust within the sterilization chamber according to the present invention.

[117] Fixing unions 102 for simply and conveniently fixing hoses of various sizes of about 1 mm to 5 mm are installed at the exhaust vents of the manifold exhaust plate 100 to pass O⁺ and OH⁺ radicals through an interior of a sterilization target. Hence, even a sterilization target such as an endoscope hose having a large length and a fine caliber can be installed and easily sterilized.

[118] FIG. 10 is a diagram illustrating a construction of the manifold exhaust plate 105 for uniform exhaust within the circular sterilization chamber according to the present invention.

[119] To make the sterilization chamber 10 in a vacuum state, the decompressor 120 comprised of a vacuum pump performs decompression. However, an amount of decompression is in an inverse proportional to a distance.

[120] If a distance from the decompressor increases, an amount of decompression decreases. This leads to a reduction of a pressure uniformity within the sterilization chamber 10. This means a difference of a sterilization efficiency depending on a position of a sterilization target within the sterilization chamber 10.

[121] Thus, the solution to the disadvantage is provided and a pressure within the sterilization chamber is uniformly maintained, thereby guaranteeing a sterilization uniformity. For this, the exhaust vent of the manifold exhaust plate 105 increases in size as a distance from the decompressor 120 increases. By doing so, a pressure distribution is the same even in any position in the sterilization chamber because of a regular exhaust amount.

[122] When an endoscope hose is installed at the union of the manifold exhaust plate 105, plasma radicals can be discharged, flowing inside/outside the endoscope hose. By doing so, a mere general sterilization process achieve an efficient sterilization of the elongate endoscope hose.

[123] FIGS. 9 and 10 show the manifold exhaust plates of the rectangular-shaped sterilization apparatus and the circular-shaped sterilization apparatus. All of the manifold exhaust plates are equipped with the unions for installing an elongate hose type.

[124] FIG. 11 illustrates the automatic impedance matcher 40 for automatic impedance matching depending on a chamber impedance at the time of plasma generation.

[125] The automatic impedance matcher 40 is a device for automatically matching an impedance between the sterilization chamber 10 and the high frequency power supply unit 50. The automatic impedance matcher 40 is used to apply a high frequency power generated from the high frequency power supply unit 50 to the sterilization chamber 10 without loss, thereby achieving easy plasma ignition even at less power level and automatic matching according to a variation of an impedance of the sterilization chamber 10.

[126] The impedance of the sterilization chamber 10 of the present invention is about a few of ohms and an impedance matching circuit is constructed as shown in FIG. 11.

[127] The automatic impedance matcher detects a voltage, a current, and a phase of a power applied from a high frequency generating unit and varies two vacuum capacitors, thereby performing impedance matching. As described above, the impedance of the sterilization chamber varies depending on a chamber pressure, a gas amount, an inter-electrode distance, a sterilization target amount, etc. Hence, the automatic impedance matcher is designed to automatically match to such variation.

[128] An impedance circuit design program used in the plasma radical sterilization apparatus uses the impedance matching circuit of the automatic impedance matcher of FIG. 11.

[129] A matching range is automatically adjusted using a new circuit value by simply varying a value of each part (Cl, C2 Ll, L2, etc.) of FIG. 11. In the case of using program according to the present invention, impedance matching can be easily designed without a particular circuit design technology.

[130] FIG. 12 is a real-time graph displaying a matching format and an example of a digital display screen in the plasma radical sterilization apparatus according to the present invention.

[131] Impedance matching between the sterilization chamber 10 and the high frequency power supply unit 50 is implemented by each part (Cl, C2, Ll, L2, etc.) of FIG. 11. The impedance matching is expressed by a forward wave (P ) and a reflected wave (P ). ™°

REF

[132] Upon execution of impedance matching, a processing status of a sterilization work can be smoothly checked by real-time displaying such power variation and a driving variation of each device on a monitor as in FIG. 12. Also, trace data is stored for a subsequent analysis of a sterilization process.

[133] In FIG. 12, a control parameter for more quick and stable impedance matching is a solultion to a conventional disadvantage of hardware adjustment and thus enables software adjustment, thereby improving worker's safety and efficiency.

[134] FIG. 13 is a flowchart illustrating a plasma radical sterilization method according to the present invention.

[135] The plasma radical sterilization method of the present invention ionizes a sterilizer as plasma and uses radicals generated from the ionization for sterilization.

[136] Plasma, the fourth matter of substance, is generated by supplying oxygen (O ) or ozone (O ) and applying a high frequency power. Plasma contains a large amount of O + radicals. On the basis of such a basic technology, plasma is generated by vaporizing and supplying hydrogen peroxide (H O ) and applying a high frequency. If so, a large amount of OH⁺ radicals is generated.

[137] The thus generated O⁺ and OH⁺ radicals have much greater oxidation force and fast oxidation speed compared to oxygen (O ), ozone (O ), and hydrogen peroxide (H O ). This directly leads to a powerful sterilizing power.

[138] To use radicals having a smaller size than gas or liquid molecule, the present invention vaporizes liquid using the vaporizer 30, injects a gaseous sterilizer (H O ) together with oxygen (O ) into the sterilization chamber, and applies a high frequency power, thereby generating plasma. The generated OH⁺ and O⁺ radicals are used as a sterilizer.

[139] A plasma radical sterilization method will be described with reference to FIG. 13. In Step 500, a sterilizer is put in the sterilization chamber 10.

[140] In Step 510, the sterilization chamber 10 is in a vacuum state by air passing through the manifold exhaust plate 100 if the decompressor 120 comprised of the vacuum pump is enabled for decompression and the vacuum valve of the automatic pressure controller 110 is opened to the maximum.

[141] In Step 520, if the sterilization chamber 10 is in a targeted vacuum degree (about 100 mTorr or less), the H O gas vaporized in the vaporizer 30 is put into the sterilization chamber 10 through the automatic flow controller 20 and the gas injected through the shower head 60 is uniformly sprayed.

[142] In Step 530, a combination gas of O and H O is controlled to about 100 seem to 2000 seem through the automatic flow controller 20 and a pressure within the sterilization chamber 10 is maintained at about 500 mTorr to 2000 mTorr using the automatic pressure controller 110.

[143] In Step 540, a high frequency power of about 100 to 2000 W is generated from the high frequency power supply unit 50 and so, the high frequency power is applied to both the electrodes 60 and 90 without a loss of a reflected wave by the automatic impedance matcher 40.

[144] In Step 550, the combination gas of O and H O is in a plasma state by the high frequency power. The plasma contains O⁺ and OH⁺ radicals and ions to be used for sterilization.

[145] In Step 560, plasma ions are not carried into the sterilization room 80 and only OH⁺ and O⁺ radicals are carried into the sterilization room 80 through a plurality of vents of the electrode 90, because the electrode 90 is grounded.

[146] In Step 570, a sterilization target is sterilized in the sterilization room 80 using OH⁺ and O⁺ radicals.

[147] Upon completion of sterilization in Step 580, a high frequency power supply is switched off, gas is turned off, and the sterilization chamber is in a vacuum state (about 100 mTorr or less). In Step 590, nitrogen (N ) is injected into the sterilization chamber, the sterilization chamber is in an atmospheric pressure state (760 Torr), and the sterilization target is taken out of the sterilization chamber. The plasma radical sterilization method of the present invention is automatically performed with one-time switch manipulation.

[148] The present invention relates to the plasma radical sterilization apparatus and method. In the present invention, a vaporized sterilizer is injected into the decompressed sterilization chamber 10 using the high temperature sterilizer supply line unit 130, a high frequency power supply is applied to both the electrodes 60 and 90, plasma 70 is generated, a large amount of radicals 80 is generated by ionization using the generated plasma, and the sterilization target is sterilized, exposed to the radicals.

[149] The present invention provides the sterilization apparatus for generating a sterilizer as radicals having several times to dozens of times of an oxidation force and a sterilizing power of an original liquid or gas molecule, using plasma.

[150] Further, in the sterilization chamber, a sterilization target can be powerfully sterilized without a damage caused by ions, voltages, and other plasma because the sterilization target gets in contact with only radicals without direct exposure to plasma.

[151] The plasma radical sterilization apparatus of the present invention has a system and an alarm function for setting a sterilization process and monitoring a progress, but since their control and display units have been well known to the art, a detailed description thereof will be omitted.

[152]

Industrial Applicability

[153] As described above, a rectangular-shaped or circular- shaped plasma radical steriliztion apparatus of the present invention has an effect of facilitating plasma generation as well as performing efficient radical generation and fast sterilization by a small amount of hydrogen peroxide (H O ), because the plasma radical sterilization apparatuses all use vaporized hydrogen peroxide (H O ) and oxygen (O ).

[154] First, the present invention can perform faster sterilization in a single process

[155] Second, the present invention can perform fast and efficient sterilization, using OH⁺ and O⁺ radicals having a smaller molecular size and a greater oxidation force than a conventional sterilizer (hydrogen peroxide (H O )).

[156] Third, a conventional sterilizer supply way (spraying) being a physical method had a difficulty in sterilizing sterilization targets a distance between which is small or a sterilization target positioned outside a sprayer region. Unlike this, in the present invention, a gas shower head and a manifold exhaust plate are installed at proper positions and radicals sterilize a sterilization target, getting in uniform contact with the sterilization target, as well as a tray storing the sterilization target is rotated to maximize such an efficiency of sterilization.

[157] Fourth, in the present invention, a plasma region is completely separated from a sterilization region in the same chamber, thereby preventing a sterilization target from being damaged by plasma.

[158] Fifth, the present invention is designed to vary a distance between a gas shower head and a cathode and thus can maintain an optimal distance upon plasma generation depending on a volume or amount of a sterilization target, provides a manifold exhaust plate with several vents having a different size on the basis of a decompression port to maintain a uniform pressure in a sterilization chamber, and efficiently sterilize an elongate hose type (endoscope parts), etc.

[159] Sixth, the present invention does not require a separate device for sterilizing an elongate hose type (endoscope parts), etc.

[160] Seventh, unlike a conventional sterilization apparatus, the present invention is simple and convenient in use in that it does not require adding a conventional supplementary process such as after-sterilization sterilizer reprocessing because sterilization is performed using plasma.

[161] Eighth, the present invention completes a sterilization process by positioning a sterilization target in a sterilization chamber and manipulating an operation switch, without a conventional inconvenient and complex process of putting a sterilization target in hydrogen peroxide (H O ) or absorbing hydrogen peroxide (H O ) on a surface of a sterilization target.

[162] Ninth, the present invention has an automatic impedance matching unit for automatically tracing and matching a chamber impedance variation. The automatic impedance matching unit can perform impedance matching, communicating with a sterilization apparatus or independently.

[163] Tenth, the automatic impedance matching unit displays a matching state by graph and digital value in real-time and has a storage unit and a circuit design program as well. [164] In addition to the above description, the present invention can implement a process of decompression, spraying, compression/heating, decompression, spraying, and compression/heating that has been implemented by a conventional sterilization apparatus and a process of putting a steriliztion target in hydrogen peroxide (H O ) or absorbing hydrogen peroxide (H O ) on a surface of the sterilization target for sterilization. The present invention can properly sterilize a sterilization target in compliance to a usage of the sterilization target, without installing a separate sterilization unit to prevent the sterilization target from being deformed due to high temperature.

[165] The present invention has an effect of monitoring a sterilization status in real-time using a radical analysis unit and when sterilization is not completed within a setting time or when a sterilization work is stopped, notifying a worker of a sterilization result through alarm or other methods, thereby preventing an accident from happening due to incomplete sterilization of a sterilization target.

[166] While the present invention has been described and illustrated herein with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made therein without departing from the spirit and scope of the invention. Thus, it is intended that the present invention covers the modifications and variations of this invention that come within the scope of the appended claims and their equivalents.

Claims

[1] A plasma radical sterilization apparatus, comprising: a vacuum controller for reducing and controlling a pressure and controlling a sterilization chamber to a set vacuum state; a flow control vaporizer for vaporizing a liquid sterilizer into a gaseous sterilizer and controlling an amount of the gaseous sterilizer suppied to the sterilization chamber; a sterilizer spray unit for uniformly spraying the gaseous sterilizer under the control of the flow control vaporizer; a high frequency impedance unit for providing a high frequency power to the sterilization chamber, generating plasma, and automatically matching an impedance of the sterilization chamber; and the sterilization chamber with a plasma region and a sterilization region independently separated, for separating radicals through an electrode from plasma, which is generated by applying a high frequency power of the high frequency impedance unit to a sterilizer sprayed from the sterilizer spray unit, and sterilizing a sterilization target using the radicals, if it is completed to control a vacuum state by the vacuum controller, control an amount of a sterilizer by the flow control vaporizer, and spray the sterilizer by the sterilizer spray unit.

[2] The apparatus of claim 1, wherein the sterilization chamber comprises a plasma unit for controlling generated plasma by installing the sterilizer spray unit spraying gas and serving as an anode and the electrode serving as a cathode.

[3] The apparatus of claim 2, wherein the electrode has a plurality of vents and passes radicals whose electric property is controlled among the generated plasma.

[4] The apparatus of claim 1 , wherein the sterilization chamber comprises a sterilization room for sterilizing a sterilization target by radicals generated from plasma.

[5] The apparatus of claim 1, wherein the sterilizer spray unit sprays a gaseous sterilizer using a shower head in a rectangular-shaped sterilization apparautus.

[6] The apparatus of claim 5, wherein in the shower head, a clamp is installed outside of the sterilization chamber and moves up/down in position and adjusts a density of generated plasma.

[7] The apparatus of claim 6, wherein the shower head comprises: a plate serving as an anode and having a plurality of holes; a sterilizer supply line for supplying gas to the plate; and the clamp connecting to the supply line and supplying a high frequency power.

[8] The apparatus of claim 1, wherein the sterilizer spray unit sprays a gaseous sterilizer using a gas tube in a circular-shaped sterilization apparatus.

[9] The apparatus of claim 1, wherein the sterilization chamber comprises: a tray for putting a sterilization target; a motor for providing a rotary power; a coupling unit connecting to the motor, coupling with the tray, and rotating the tray; and a rotation unit having a bearing supporting tray rotation, and horizontally or vertically rotating the sterilization target for sterilization.

[10] The apparatus of claim 1, wherein the sterilization chamber comprises: a manifold exhaust plate with exhaust vents of various sizes, for enabling the sterilization chamber to have the same pressure distribution; and a union for enabling installation of a hose type at the exhaust vent and enabling sterilization of even an elongate hose.

[11] The apparatus of claim 1, wherein the sterilization chamber has a top plasma unit and a bottom sterilization unit in a rectangular-shaped radical sterilization apparatus, the top plasma unit generating plasma and carrying radicals, and the bottom sterilization unit performing sterilization.

[12] The apparatus of claim 1, wherein in a circular-shaped plasma radical sterilization apparatus, the sterilization chamber generates plasma in a form in which a plasmsa unit surrounds, by 360 degrees, a sterilization unit for sterilizing a sterilization target, and provides radicals to the sterilization unit for sterilization.

[13] The apparatus of claim 1, wherein the flow control vaporizer comprises: a vessel supplied with oxygen for carrying a sterilizer and generating plasma, and supplied with the sterilizer; a heater for heating the vessel; a temperature controller for controlling a temperature of the sterilizer within the vessel and controlling vaporization; and a line heater connecting with a supply line for a vaporized sterilizer gas, controlling a temperature of the supply line, and preventing a liquefaction of the sterilizer gas.

[14] The apparatus of claim 1, wherein the high frequency impedance unit comprises: an automatic impedance matcher for, upon provision of a high frequency power to the sterilization chamber, automatically matching an impedance of the sterilization chamber, detecting a voltage, a current, and a phase of the high frequency power, and varying a vacuum capacitor, thereby automatically performing impedance matching.

[15] A plasma radical sterilization method comprising: a first process of decompressing and making a sterilization chamber vacuous by a set value; a second process of putting a sterilizer into the sterilization chamber, uniformly spraying the sterilizer through a sterilizer spray unit, and controlling an amount of the sterilizer and a pressure intensity of the sterilization chamber; a third process of generating and applying a high frequency power to the sterilizer spray unit and an electrode and generating the sterilizer in a plasma state; and a fourth process of carrying only radicals among the plasma to a sterilization room within the sterilization chamber and sterilizing a sterilization target. [16] The method of claim 15, wherein the radicals comprise O⁺ radicals and OH⁺ radicals. [17] The method of claim 15, wherein the first process comprises: putting a sterilization target in the sterilization chamber and decompressing the sterilization chamber using a vacuum pump; opening a vacuum valve to the maximum to control a pressure; and making the sterilization chamber vacuous by a set value through a manifold exhaust plate. [18] The method of claim 15, wherein the fourth process comprises: carrying only radicals among the plasma to the sterilization room through a plurality of vents; and horizontally or vertically rotating while sterilizing a sterilization target provided in the sterilization room. [19] The method of claim 15, wherein the fourth process comprises: upon completion of sterilization of the sterilization target, stopping sterilizer supply and the high frequency power; opening the vacuum valve to the maximum and making the sterilization chamber vacuous; injecting nitrogen (N ) into the sterilization chamber and making the sterilization chamber in an atmospheric pressure state; and taking a sterilization target out of the sterilization chamber. [20] The method of claim 15, wherein the sterilizer is vaporized into gas for use in case where the sterilizer is liquid. [21] The method of claim 15, wherein the sterilizer spray unit uses a shower head in a rectangular- shaped sterilization apparatus. [22] The method of claim 15, wherein the sterilizer spray unit uses a gas tube in a circular-shaped sterilization apparatus.