JP2006296848A - Atmospheric-pressure plasma sterilization apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an atmospheric-pressure plasma sterilization apparatus having a high sterilizing capacity and reducing the cost of the apparatus. <P>SOLUTION: An atmospheric-pressure surface wave excitation plasma unit 2 is connected to the upper part of the side of a treatment chamber 1 storing a sterilization object. When performing the sterilization, gas (for example, mixed gas of oxygen gas and argon gas) from a gas supply part 3 is introduced from a treatment chamber lower part, and the atmosphere in the treatment chamber 1 is exhausted from a pipe D3 connected to the treatment chamber upper part. When performing the sterilization, the gas in the treatment chamber 1 is circulated between the treatment chamber 1 and the ASWP (atmospheric-pressure surface wave excitation plasma) unit 2 via a pipe D4. The oxygen gas contained in the circulating gas is activated by the plasma in the ASWP unit 2 to generate oxygen radical. The oxygen radical is guided to an atmospheric-pressure treatment chamber 1 to sterilize the sterilization object by the strong sterilizing effect of the oxygen radical. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for sterilizing medical instruments and the like, and relates to an atmospheric pressure plasma sterilization apparatus using atmospheric pressure plane wave excitation plasma.

  Conventional methods for sterilizing medical instruments include chemical methods such as EO (ethylene oxide) gas sterilization and reduced-pressure hydrogen peroxide plasma sterilization, and physical methods include high-pressure steam sterilization (autoclave). ), Gamma ray sterilization method, electron beam sterilization method and the like. A sterilization method using microwave plasma is also known (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 2004-223038

  However, in the case of the E.O. gas sterilization method, ethylene oxide gas itself is extremely toxic and explosive, so that it is difficult to handle and the effect on the environment becomes a problem. This necessitates detoxification treatment of residual gas and exhaust gas, which increases the cost for detoxification. In addition, the reduced pressure hydrogen peroxide plasma sterilization method and the sterilization method using microwave plasma are performed under reduced pressure, and conversely, the high pressure steam sterilization method is performed under high pressure. Become high. Further, the gamma ray sterilization method and the electron beam sterilization method require a device for generating gamma rays and an electron beam, so that the device becomes large-scale and high in cost, and is not suitable for a small-scale sterilization device.

The atmospheric pressure plasma sterilization apparatus according to the invention of claim 1 includes a processing chamber in which an object to be sterilized is accommodated and maintained at substantially atmospheric pressure, and a radical generator that generates radicals by generating atmospheric pressure surface wave excitation plasma. And sterilizing an object to be sterilized with radicals generated by the radical generator.
The invention according to claim 2 is the atmospheric pressure plasma sterilization apparatus according to claim 1, wherein the radical generation unit generates radicals by atmospheric pressure surface wave excitation plasma in a space different from the processing chamber, and generates radicals during sterilization processing. And introducing means for introducing radicals generated in the section into the processing chamber.
A third aspect of the present invention provides the atmospheric pressure plasma sterilization apparatus according to the second aspect, wherein a plurality of treatment chambers are provided for one radical generation unit, and the introducing means includes a plurality of radicals generated by the radical generation unit. Each is introduced into a processing chamber.
According to a fourth aspect of the present invention, there is provided the atmospheric pressure plasma sterilization apparatus according to the second or third aspect, wherein the introduction means is provided with a transfer means for introducing the radical introduced into the processing chamber downward into the upper region of the processing chamber. It is a thing.
A fifth aspect of the present invention is the atmospheric pressure plasma sterilization apparatus according to any one of the second to fourth aspects, wherein a gas supply means for introducing a radical generating gas into a lower region in the processing chamber, and an upper portion of the processing chamber. Discharging means for discharging the gas in the processing chamber, and circulation means for circulating the radical generating gas introduced into the processing chamber between the processing chamber and the radical generating portion, the radical generating portion being guided by the circulating means. The radical is generated using the radical generating gas.
The invention of claim 6 is the atmospheric pressure plasma sterilization apparatus according to any one of claims 1 to 5, wherein after the sterilization treatment, the dry air is passed through the atmospheric pressure surface wave excitation plasma generated in the radical generation unit. The dry air supply means for supplying the passed dry air to the processing chamber is provided.

  According to the present invention, since the object is sterilized by radicals generated by generating atmospheric pressure surface wave excitation plasma, the processing chamber is maintained at substantially atmospheric pressure, and the processing chamber and the pressure vessel are It is not necessary to reduce the cost, and at the same time, it is not necessary to adjust the pressure, and quick processing is possible. In addition, the sterilization effect by radicals is strong, and the processing time is shortened.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of an atmospheric pressure plasma sterilization apparatus according to the present invention, and is a diagram showing a schematic configuration of the entire apparatus. The atmospheric pressure plasma sterilization apparatus according to the present embodiment can sterilize and disinfect various items such as sterilization of medical instruments and sterilization / disinfection of food packaging containers under almost atmospheric pressure.

  Reference numeral 1 denotes a chamber constituting a processing chamber. A sterilization process is performed by storing a medical instrument or the like to be sterilized in a processing unit 1 in a holding unit (not shown) (for example, a table or a shelf). An atmospheric pressure surface wave excited plasma (ASWP) unit 2 is connected to the upper side surface of the processing chamber 1. The ASWP unit 2 is a device that generates plasma under atmospheric pressure to radicalize the sterilization gas, which will be described in detail later.

The gas supply unit 3 includes oxygen (O ₂ ) gas and hydrogen peroxide (H ₂ O ₂ ) gas for generating oxygen radicals or hydroxy radicals, argon (Ar) gas for causing discharge, and dry air. Then, the gas is supplied to the processing chamber 1 and the ASWP unit 2 through the gas supply pipes D1 and D2. Below, the case where oxygen gas is used as gas for generating a radical is demonstrated. In FIG. 1, the direction indicated by the broken line arrow is the vertical vertical direction, and the pipe D1 is connected to the bottom surface of the processing chamber 1 via the valve V4. On the other hand, a gas exhaust pipe D3 is connected to the upper surface of the processing chamber 1, and a diffusion fan F3 is provided to blow the gas in the processing chamber 1 downward and diffuse radicals described later.

  The exhaust pipe D3 is provided with a valve V1 and an exhaust fan F2 for forcibly exhausting the gas in the processing chamber 1. The pressure in the processing chamber 1 is detected by a pressure gauge PG. The processing chamber 1 is configured as a container for atmospheric pressure, and if the pressure difference between the pressure in the processing chamber 1 and the pressure in the exhaust line exceeds a predetermined pressure (for example, 1.01 atm), the processing chamber 1 is placed on the bottom of the processing chamber. The provided relief valve LV is opened so that the gas in the processing chamber 1 is released to the exhaust line. That is, the pressure in the processing chamber 1 is maintained at almost atmospheric pressure even during the sterilization process.

  The exhaust fan F1 provided at the lower part of the processing chamber 1 is a fan for sending the gas in the processing chamber 1 to the ASWP unit 2 or the exhaust line, and opens the valves A and B of the three-way valve V2 and closes the valve C. Then, the gas in the processing chamber 1 is discharged to the exhaust line. On the other hand, when the valves B and C of the three-way valve V2 are opened and the valve A is closed, the gas in the processing chamber 1 is sent to the ASWP unit 2 via the circulation pipe D4.

  FIG. 2 is a diagram showing the overall configuration of the ASWP unit 2, and FIG. 3 shows a cross section of the plasma generation unit 10 in the axial direction (front and back direction in FIG. 2). As shown in FIG. 2, the ASWP unit 2 includes a plasma generation unit 10 and a microwave supply unit 20 that supplies a microwave to the plasma generation unit 10. The microwave supply unit 20 includes a microwave power source 21, a microwave oscillator 22, an isolator 23, a directional coupler 24, a matching unit 25, and a waveguide 26. The isolator 23, the directional coupler 24, and the matching unit 25 may be omitted.

  For example, a microwave of 2.45 GHz generated by the microwave oscillator 22 is guided to the annular waveguide 11 of the plasma generation unit 10 by the waveguide 26. 2 is a cross-sectional view taken along the line CC of FIG. 3 and is a cylindrical dielectric formed of quartz, alumina or the like so as to be in contact with the inner surface of the annular waveguide 11. A body tube 12 is disposed. A plurality of slot antennas 110 having slit-like openings are formed on the inner side surface of the annular waveguide 11 at predetermined intervals.

  Reference numeral 11a denotes a termination plate provided in the annular waveguide 11, and the microwave introduced into the annular waveguide 11 from the waveguide 26 is reflected by the termination plate 11a. The circumferential length of the annular waveguide 11 is set to an integral multiple of the in-tube wavelength, and the termination plate 11a is provided to optimize the position of the standing wave in the annular waveguide 11 and the slot antenna 110. Efficiency can be improved.

  The annular waveguide 11 is made of, for example, an aluminum alloy or nonmagnetic stainless steel, and cooling jackets 111 are attached to the left and right end faces of the annular waveguide 11 as shown in FIG. A coolant passage 112 is formed in the cooling jacket 111, and the annular waveguide 11 is cooled by flowing a coolant through the passage 112. An O-ring seal 113 attached to the cooling jacket 111 seals between the end face of the dielectric tube 12 and the cooling jacket 111.

  The microwaves radiated from the slot antennas 110 of the annular waveguide 11 spread as surface waves on the inner peripheral surface of the dielectric tube 12, and the argon gas introduced into the dielectric tube 12 is excited by the surface waves. And turn into plasma. In the plasma generation unit 10 shown in FIG. 2, since the surface wave spreads over the entire wall surface of the cylindrical dielectric tube 12, high-density plasma can be efficiently formed in the internal space of the dielectric tube 12. 114 is a cylindrical shield provided to prevent heating by plasma, and is made of alumina, quartz, titanium or the like.

  Since the high-density region of the plasma is formed near the wall surface of the dielectric tube 12, for example, when the gas is spirally introduced as indicated by the broken line L, the gas flows near the wall surface of the dielectric tube 12. , Plasma is efficiently formed. When oxygen gas is allowed to flow from the left side to the right side of the formed plasma region, the oxygen gas is activated by the plasma, and oxygen radicals (superoxide, singlet oxygen) are generated. When hydrogen peroxide gas is allowed to flow instead of oxygen gas, hydroxy radicals are generated. All radicals are excellent in sterilization ability. The generated radicals are guided to the processing chamber 1 by the gas flow.

  FIG. 4 is a process diagram showing the procedure of sterilization treatment. FIG. 5 shows the operation of the valve, the exhaust fan, and the ASWP unit 2 in each step shown in FIG. In the case of performing sterilization, in the apparatus of the present embodiment, a gas filling method (FIG. 5A) in which processing is performed by filling the processing chamber 1 with gas, and gas flows into and out of the processing chamber 1. Both of the gas flow method and the gas flow method (FIG. 5B) can be employed.

  First, the gas filling process shown in FIG. 5A will be described. Step 1 in FIG. 4 is a preparatory step before starting the sterilization process. The sterilization target instrument is accommodated in the process chamber 1 and the gas replacement / filling operation in the process chamber 1 is performed. In this step 1, as shown in FIG. 5 (A), the discharge side valve V1 is opened and the supply side valve V4 is opened, and a mixed gas in which argon gas is added to the oxygen gas from the gas supply unit 3 by several percent. Into the processing chamber 1.

  Oxygen gas and argon gas having a high specific gravity are sequentially filled from the lower part of the processing chamber 1, and the atmosphere in the processing chamber 1 is pushed upward by the mixed gas. At this time, the exhaust fan F2 provided in the exhaust pipe D3 is turned on, and the air pushed upward is forcibly exhausted to the exhaust line by the exhaust fan F2. Further, regarding the three-way valve V2, the valves B and C are opened and the valve A is closed so that the gas in the processing chamber 1 is circulated also to the ASWP unit 2 via the pipe D4.

  In this manner, the atmosphere filled in the processing chamber 1 and the ASWP unit 2 is discharged through the valve V1, and the mixed gas is filled into the processing chamber 1 through the valve V4. If the gas in the processing chamber 1 and the ASWP unit 2 is finally replaced in the processing chamber 1 from the bottom, the processing chamber 1 is finished and the processing proceeds to the processing step 2. In step 1, the valve V3 is closed and the exhaust fan F1 and the ASWP unit 2 are turned off.

  In step 2, the ASWP unit 2 is turned on to start discharging. At the start of discharge, the valves V1 and V4 are closed and the exhaust fan F2 is turned off. Further, at the time of discharging, the valve V3 is opened for about 2 seconds, and argon gas (or a mixed gas of argon gas and oxygen gas), which is a discharge gas, is caused to flow into the ASWP unit 2 so that discharge is easily generated. If discharge starts and plasma is generated, the valve V3 is closed.

  If the discharge starts in step 2, the process proceeds to step 3 for maintaining the discharge, the exhaust fan F1 is turned on, and the gas in the processing chamber 1 is circulated to the ASWP unit 2. Further, the diffusion fan F3 provided in the processing chamber 1 is rotated. When plasma is generated in the ASWP unit 2, oxygen gas is activated by the action of the plasma, and a large amount of oxygen radicals are generated. Oxygen radicals generated in the ASWP unit 2 are supplied from the ASWP unit 2 to the processing chamber 1 by the flow of gas circulating through the distribution processing chamber 1, the pipe D 4 and the ASWP unit 2.

  Since the gas in the processing chamber 1 is mixed and diffused by the diffusion fan F3, the oxygen radicals are evenly distributed in the processing chamber 1 and flow down to the sterilization target device from the top to the bottom. Wrap around behind the target device. As a result, bacteria and viruses attached to the sterilization target device are killed by the strong sterilization action of oxygen radicals. Oxygen radicals and hydroxy radicals generated by the ASWP unit 2 have a strong sterilization action, and thus the sterilization process is completed by a process of several minutes. In addition, in the conventional sterilization apparatus using ethylene oxide, the treatment state must be maintained for about one week, and time is also required for the subsequent detoxification treatment.

  If the sterilization process is completed by continuing the discharge maintenance in step 3 for a predetermined time, the process proceeds to step 4 to turn off the ASWP unit 2 and stop the discharge. In the subsequent step 5, the gas in the processing chamber 1 is exhausted and replaced with dry air. That is, by opening the valves V1 and V4 and opening the valves A and B of the three-way valve V3 and closing the valve C, sterilized dry air is supplied from the gas supply unit 3 and sterilized and dried to the processing chamber 1 via the valve V4. Allow air to flow in.

  At this time, the diffusion fan F3 is stopped and the exhaust fans F1 and F2 are driven so that the gas (oxygen gas, argon gas, oxygen radicals, etc.) in the process chamber 1 flows from the lower and upper portions of the process chamber 1 to the exhaust line. Discharge. When the predetermined time has elapsed and the replacement of the gas in the processing chamber 1 with the sterilized dry air is completed, the step 5 is terminated. Thereafter, the processing chamber 1 is opened to the atmosphere, and instruments that have been sterilized are removed.

  On the other hand, the gas flow process is performed in the same process as in FIG. 4, but the operation of valves and the like in process 2 and process 3 is different from that in the gas filling process, as shown in FIG. Yes. That is, in the discharge start process of step 2, the valve V3 is opened, and a mixed gas of argon gas and oxygen gas is always supplied from the gas supply unit 3 to the ASWP unit 2. Further, when the exhaust fan F1 is driven and the valves A and B of the three-way valve V2 are opened and the valve C is closed, the gas in the processing chamber 1 is forcibly discharged to the exhaust line by the exhaust fan F1.

  That is, in step 2, the mixed gas is supplied from the side surface to the processing chamber 1 via the valve D3 and the ASWP unit 2 from the pipe D2, and is discharged from the lower portion of the processing chamber 1 after being downflowed by the diffusion fan F3. Is done. In step 3, the same gas flow as in step 2 is employed. Other processes are the same as those in the gas filling method.

  In the above description, in step 5, sterilized dry air is supplied from the gas supply unit 3 to perform gas replacement in the processing chamber 1, but mere dry air is supplied from the pipe D2 while the ASWP unit 2 is in operation. It is also possible to provide sterilized dry air by supplying and passing dry air through the plasma.

(Modification)
FIG. 6 is a diagram showing a modification of the atmospheric pressure plasma sterilization apparatus shown in FIG. In this modification, two processing chambers 1A and 1B are provided, and radicals (oxygen radicals and hydroxy radicals) generated in the ASWP unit 2 are guided to the processing chambers 1A and 1B through a pipe D100. The piping D100 is provided with valves V100 and V101, and the supply of radicals from the ASWP unit 2 to the processing chambers 1A and 1B can be independently turned on and off by opening and closing the valves V100 and V101. That is, by controlling the opening and closing of the valves V100 and V101, the sterilization process can be performed in one of the processing chambers 1A and 1B, or both can be performed simultaneously. Note that three or more processing chambers may be provided for one ASWP unit 2.

  In addition, the structure regarding the process chamber 1 other than ASWP unit 2, valve | bulb V3, piping D2, and gas supply part 3 in FIG. 1 is each provided in each process chamber 1A, 1B of FIG. That is, pipes D11 and D12 correspond to pipe D1, pipes D31 and D32 correspond to pipe D3, pipes D41 and D42 correspond to pipe D4, valves V11 and V12 correspond to valve V1, three-way valve V21, V22 corresponds to three-way valve V2, valves V41 and V42 correspond to valve V4, relief valves LV1 and LV2 correspond to relief valve LV, exhaust fans F11 and F12 correspond to exhaust fan F1, exhaust fan F21, F22 corresponds to the exhaust fan F2, diffusion fans F31 and F32 correspond to the diffusion fan F3, and pressure gauges PG1 and PG2 correspond to the pressure gauge PG.

The atmospheric pressure plasma sterilization apparatus of the present embodiment described above has the following operational effects.
(1) Since radicals are generated by the ASWP unit 2, sterilization can be performed at normal pressure. Therefore, it is not necessary to use the processing chamber 1 as a pressure vessel, and the cost of the apparatus can be reduced. Moreover, sterilization can be performed at normal temperature.
(2) Since no toxic or explosive gas is used, handling is easy and no detoxification treatment is required.
(3) By using the ASWP unit 2, a plasma having a higher density and a larger plasma region than before can be obtained, and a larger amount of radicals are generated. By utilizing the large amount of radicals for sterilization, sterilization can be effectively performed. In addition, since the radical sterilization ability is high, the sterilization time can be shortened.

(4) Since gas is introduced from the lower portion of the processing chamber and gas is discharged from the upper portion of the processing chamber, gas replacement can be performed quickly, and the total processing time including the processing before and after the sterilization processing is reduced. It can be shortened.
(5) Disperse radicals using a diffusion fan, and sufficiently diffuse by downflowing from the upper side to the lower side of the processing chamber, and uniformly over the entire surfaces of a plurality of instruments to be sterilized accommodated in the processing chamber Sterilization can be performed.
(6) In the case of the gas filling method, since oxygen gas is circulated between the processing chamber 1 and the ASWP unit 2, radicals are efficiently supplied to the processing chamber 1.
(7) As shown in FIG. 6, by providing a plurality of processing chambers with one ASWP unit 2, it is possible to increase the processing capacity while suppressing an increase in cost.
(8) By sterilizing the dry air from the gas supply unit 3 with the plasma of the ASWP unit 2 and supplying it to the processing chamber 1, there is no need to newly provide a device for supplying sterilized dry air.

  In the above-described embodiment, the ASWP unit 2 is provided separately from the processing chamber 1 and radicals generated in the ASWP unit 2 are introduced into the processing chamber 1. However, the ASWP unit 2 may be provided in the processing chamber 1. good.

  In the correspondence between the embodiment described above and the elements of the claims, the ASWP unit 2 is a radical generator, the pipe D100 and the valves V100 and V101 are introduction means, the pipe D4, the three-way valve V2 and the exhaust fan F1 are Introducing means and circulating means, diffusion fan F3 as transfer means, gas supply unit 3, pipe D1 and valve V4 as gas supply means, pipe D3, valve V1 and exhaust fan F2 as discharge means, pipe D4 and three-way valve V2 and the exhaust fan F1 constitute circulation means, and the gas supply unit 3, the pipe D2 and the valve V3 constitute dry air supply means, respectively. The above description is merely an example, and when interpreting the invention, there is no limitation or restriction on the correspondence between the items described in the above embodiment and the items described in the claims.

It is a figure which shows one Embodiment of the atmospheric pressure plasma sterilization apparatus by this invention. FIG. 2 is a diagram illustrating an overall configuration of an ASWP unit 2. FIG. 2 is a diagram showing an axial cross section of a plasma generation unit 10. It is process drawing which shows the procedure of a sterilization process. FIG. 5 is a diagram showing operations of a valve, an exhaust fan, and an ASWP unit 2 in each step shown in FIG. 4. It is a figure which shows a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Processing chamber 2 ASWP unit 3 Gas supply part 10 Plasma production | generation part 11 Annular waveguide 12 Dielectric tube
D1 to D4, D11, D12, D31, D32, D41, D42, D100 Piping
F1, F2, F11, F12, F21, F22 exhaust fan
F3, F31, F32 diffusion fans
V1, V3, V4, V11, V12, V41, V42, V100, V101 Valve
V2, V21, V22 3-way valve

Claims (6)

A processing chamber in which objects to be sterilized are stored and maintained at approximately atmospheric pressure;
A radical generating unit that generates radicals by generating atmospheric pressure surface wave excitation plasma,
An atmospheric pressure plasma sterilization apparatus that sterilizes an object to be sterilized with radicals generated by the radical generator. In the atmospheric pressure plasma sterilizer according to claim 1,
The radical generating unit generates radicals by atmospheric pressure surface wave excitation plasma in a space different from the processing chamber,
An atmospheric pressure plasma sterilization apparatus comprising an introducing means for introducing radicals generated in the radical generation unit during sterilization into the processing chamber. In the atmospheric pressure plasma sterilizer according to claim 2,
A plurality of the treatment chambers are provided for one radical generation unit,
The atmospheric pressure plasma sterilization apparatus, wherein the introduction unit introduces radicals generated by the radical generation unit into the plurality of processing chambers. In the atmospheric pressure plasma sterilizer according to claim 2 or 3,
The introducing means is introduced into the upper region of the processing chamber;
An atmospheric pressure plasma sterilization apparatus comprising a transfer means for sending the radical introduced into the processing chamber downward. In the atmospheric pressure plasma sterilization apparatus according to any one of claims 2 to 4,
A gas supply means for introducing a radical generating gas into a lower region in the processing chamber;
Discharging means for discharging the gas in the processing chamber from the upper part of the processing chamber;
A circulation means for circulating the gas for generating radicals introduced into the processing chamber between the processing chamber and the radical generating unit;
The atmospheric pressure plasma sterilization apparatus, wherein the radical generation unit generates radicals using radical generation gas introduced by the circulation means. In the atmospheric pressure plasma sterilization apparatus according to any one of claims 1 to 5,
After the sterilization process, there is provided a dry air supply means for passing the dry air through the atmospheric pressure surface wave excitation plasma generated in the radical generating unit and supplying the passed dry air to the processing chamber. Atmospheric plasma sterilizer.

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