JP2006020950A - Plasma sterilizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma sterilizer capable of securely and inexpensively sterilizing a treated object by generating high density oxygen radicals. <P>SOLUTION: A storage means 1 for storing the treated object is kept under low pressure by a low pressure maintaining means 2, and oxygen gas is fed to the storage means 1 from an oxygen gas feeding means 3. Oxygen in the oxygen gas is made plasmatic so that oxygen radicals are generated. Accordingly, the oxygen radicals can be maintained as a simple substance for a long period of time and can be generated at a high density, and therefore, the treated object can be sterilized securely and inexpensively. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a plasma sterilization apparatus that sterilizes an object to be processed such as medical equipment with active oxygen, and more particularly to a plasma sterilization apparatus that sterilizes an object to be processed with oxygen radicals generated in oxygen gas plasma.

  Background Art Plasma sterilizers as background art include those disclosed in Japanese Patent Laid-Open No. 10-99415 (first background art) and Japanese Patent Laid-Open No. 7-18461 (second background art). Each background art is shown in FIG. 5 and FIG.

  In FIG. 5, the plasma sterilization apparatus according to the first background art can arrange a first chamber 114 having a plasma generator 112 that generates plasma at atmospheric pressure, and an object 136 to be processed, and has a pressure-resistant structure. A compressor that is a pressurizing device and a second chamber 118, an open / close valve 120 that couples the two chambers in an openable and closable manner, and controls the flow of a gas containing a sterilizing factor supplied from the first chamber into the second chamber 118. And a connecting pipe 124 provided with 122. A pressure regulator 116 is connected to the second chamber 118 to keep the internal air pressure constant by sucking and discharging the gas in the chamber 118. In the plasma generator 112, it is possible to ionize at least a part of a mixture of gas and liquid using a pulse power source, and the ionized mixture thus obtained becomes a sterilizing factor.

  In this manner, the first chamber 114 for storing the sterilizing factor is provided separately from the second chamber 118 for sterilizing the workpiece 136, and both are connected by the connecting pipe 124 having the opening / closing valve 120. Storage of sterilization factor necessary for sterilization and pretreatment such as drying of the object to be processed can be performed in parallel, and a considerable amount of sterilizing factor can be brought into contact with the object to be processed in a short time. Thus, effective sterilization can be performed efficiently.

Further, in FIG. 6, the plasma sterilization apparatus according to the second background art opens the lid 202, puts the container 218 to be sterilized into the vacuum container 201, then closes the lid 202, and vacuum container 204 by the vacuum pump 204 The inside is evacuated until it becomes sufficiently lower than the pressure at which plasma is generated, then gas is introduced from the gas source 214 at an appropriate flow rate, and the valve 215 is adjusted to maintain a pressure suitable for the plasma. On the other hand, after the vacuum pump 204 has been operated to stabilize the pressure, a high frequency power is applied to the electrode 208 from the high frequency power supply 212 to generate plasma in the container 218, and the plasma is maintained for a period of time when sufficient sterilization is performed. Thereafter, the application of the high frequency power is stopped and the container 218 is sterilized. At the same time as the application of the high-frequency power is stopped, the introduction of gas is stopped and the vacuum pump is stopped after exhausting for a while. Next, the atmosphere introduction valve 217 is opened to introduce the atmosphere, and then the lid 202 is opened to take out the container 218.
JP-A-10-99415 Japanese Patent No. 3209944

  Since the plasma sterilization apparatus according to the first background art is configured as described above, even if oxygen radicals are generated by generating plasma in the first chamber 114 at atmospheric pressure, The oxygen radicals are bonded to the gas existing in the first chamber 114 at atmospheric pressure, for example, oxygen, hydrogen, nitrogen, etc. in a very short time, and cannot exist as oxygen radicals alone, so that a sufficient sterilization effect is obtained. There is no problem.

  Further, the plasma sterilization apparatus according to the second background art is intended to sterilize the container 218 to be sterilized in the vacuum container 120, and generates plasma composed of a mixed gas of an inert gas and a reactive gas. Since the plasma P is generated by introducing the working gas, oxygen radicals alone cannot be generated at high density, and the target container 218 cannot be reliably sterilized. The sterilization in the second background art means that microbiologically kills microorganisms to reduce the number of survivors, and is greatly different from killing or removing all substances to be sterilized and microorganisms in the surrounding space. .

  Furthermore, as a plasma sterilization apparatus according to another background art, there is an apparatus that uses hydrogen peroxide as a source gas, generates hydroxyl (OH) radicals, and performs sterilization with the sterilization ability of the hydroxyl (OH) radicals. However, since this hydrogen peroxide is a liquid at room temperature and normal pressure, when introducing a liquid into a low-pressure plasma vessel, both the structure of the device and the operation method (pressure adjustment) become complicated, and overoxidation occurs. Since hydrogen is expensive, both the device itself and the running cost have a problem of high price.

  In particular, when performing a sterilization process by switching the pressure in a container for storing an object to be sterilized between a high vacuum state and a low vacuum state, using hydrogen peroxide as a liquid as a source gas, Pressure adjustment is an extremely difficult operation, and there are problems such as that it takes a long time to uniformly diffuse hydroxyl radicals into the container.

  The present invention has been made to solve the above problems, and provides a plasma sterilization apparatus capable of generating oxygen radicals at high density and sterilizing an object to be processed reliably and inexpensively.

  The plasma sterilization apparatus according to the present invention stores an object to be sterilized, a storage unit including an airtight container, a low pressure maintaining unit that maintains a low pressure in the storage unit, Oxygen gas supply means for supplying oxygen gas to the storage means; and plasma generating means for storing at least an electrode in the storage means, and generating oxygen radicals by causing a current to flow through the electrode to convert oxygen of the oxygen gas into plasma. Is provided. As described above, in the present invention, the storage means for storing the object to be processed is maintained at a low pressure by the low pressure maintaining means, oxygen gas is supplied from the oxygen gas supply means to the storage means, and oxygen of the oxygen gas is converted into plasma. Since the generating means generates plasma to generate oxygen radicals, oxygen radicals can be maintained as a single unit for a long time and can be generated at a high density, and the object to be treated can be sterilized reliably and inexpensively.

Further, in the plasma sterilization apparatus according to the present invention, the low pressure maintaining means maintains the inside of the storage container at 3 Pa to 10 kPa as necessary. Thus, in the present invention, since the low pressure maintaining means maintains the inside of the storage container at 3 Pa to 10 kPa, oxygen (O ₂ ) is converted into plasma (2O ⁺ + 2e ⁻ ) at a higher density and oxygen is maintained. Radicals (O) can be generated, and the object to be processed can be sterilized more reliably.

  Further, in the plasma sterilization apparatus according to the present invention, the low pressure maintaining means changes the pressure of the oxygen gas in the airtight container of the storage means a plurality of times from 3 Pa to 10 kPa as necessary. As described above, in the present invention, the pressure of the oxygen gas in the airtight container of the storage means is changed a plurality of times between 3 Pa and 10 kPa. However, oxygen radicals can be permeated, and sterilization can be reliably and easily performed over the entire region of the object to be processed.

  Further, in the plasma sterilization apparatus according to the present invention, the low pressure maintaining means repeatedly changes the pressure of the oxygen gas in the airtight container of the storage means between 3 Pa and 10 kPa every 1 to 10 minutes as necessary. Is. As described above, in the present invention, the pressure of the oxygen gas in the airtight container of the storage means is repeatedly changed between 3 Pa and 10 kPa every 1 to 10 minutes. Oxygen radicals can permeate the mounting lower surface and the like, and can be sterilized reliably and easily over the entire region of the object to be processed.

  Further, in the plasma sterilization apparatus according to the present invention, the plasma generation means is constituted by inductively coupled plasma generation means as required. As described above, in the present invention, the oxygen gas is converted into plasma by the inductively coupled plasma generating means, so that higher density plasma can be generated uniformly in the airtight container, Sterilization can be performed more reliably.

  Further, in the plasma sterilization apparatus according to the present invention, as necessary, the plasma generating means is supplied with an alternating current to the electrode, and the frequency of the alternating current is set to 1 kHz to 20 kHz at the beginning of startup and 10 MHz to 60 MHz after the startup. It is. As described above, in the present invention, the alternating current supplied to the electrode of the plasma generating means is controlled so that the starting time is 1 kHz to 20 kHz and the starting time is 10 MHz to 60 MHz. In addition to facilitating the plasma generation of this, the avalanche is generated by this plasma generation, and oxygen radicals start to be generated, and then it is possible to suppress the power consumption by switching to a high frequency. The configuration can be simplified.

  In the plasma sterilization apparatus according to the present invention, the oxygen gas supply means changes the flow rate of the supplied oxygen gas between 10 sccm and 500 sccm a plurality of times as necessary. As described above, in the present invention, the flow rate of the oxygen gas to the airtight container for storing the object to be processed is changed by the oxygen gas supply means a plurality of times between 10 sccm and 500 sccm. Oxygen radicals can also permeate the part, the lower surface of the mounting, etc., and can be sterilized reliably and easily over the entire region of the object to be processed.

  Further, in the plasma sterilization apparatus according to the present invention, the oxygen gas supply means repeatedly changes the supplied oxygen gas at a flow rate of 10 sccm and a flow rate of 500 sccm every 1 to 10 minutes as necessary. As described above, in the present invention, the oxygen gas supply means repeatedly changes the flow rate of oxygen gas from 10 sccm to 500 sccm every 1 to 10 minutes. Oxygen radicals can also permeate into the fine parts of the object to be processed, the mounting lower surface, and the like, and the entire area of the object to be processed can be reliably and easily sterilized.

  In addition, in the plasma sterilization apparatus according to the present invention, the object to be processed stored in the storage means is covered with a sheet that transmits oxygen radicals as necessary. As described above, in the present invention, the object to be processed is covered with the sheet through which oxygen radicals permeate and stored in the storage means. Therefore, after sterilization and removal from the storage means, external germs are transferred to the process object. Direct adhesion does not occur and the effect of sterilization can be further improved.

(First embodiment of the present invention)
Hereinafter, a plasma sterilization apparatus according to a first embodiment of the present invention will be described with reference to FIG. This FIG. 1 shows the schematic block diagram of the plasma sterilization apparatus based on this embodiment.

  In the figure, the plasma sterilization apparatus according to the present embodiment includes a storage means 1 composed of an airtight container for storing a medical instrument (not shown) to be sterilized, and a low pressure in the storage means 1. The low pressure maintaining means 2 for maintaining the oxygen gas, the oxygen gas supply means 3 for supplying oxygen gas to the storage means 1, and at least an electrode 41 is stored in the storage means 1. The plasma generation means 4 generates oxygen radicals by converting gas oxygen into plasma.

  The low pressure maintaining means 2 includes a rotary pump 21 that discharges the air in the storage means 1, a discharge pipe 22 that is connected to the rotary pump 21 and the storage means 1, and an intermediate between the discharge pipe 22. The adjustment valve 23 is mounted and adjusts the discharge amount of air, and the connector 24 connects the discharge pipe 22 to the side wall hole of the storage means 1 in an airtight state. The oxygen gas supply means 3 includes an oxygen gas cylinder 31 that supplies oxygen gas into the storage means 1, a supply pipe 32 that communicates with and connects to the oxygen gas cylinder 31 and the storage means 1, and an intermediate between the supply pipe 32. And an adjustment valve 33 for adjusting the supply amount of oxygen gas, and a connector 34 for connecting the supply pipe 32 to the side wall hole of the storage means 1 in an airtight state.

  The plasma generating means 4 includes an electrode 41 made of an inductively coupled antenna in which a conductive wire is wound in a spiral shape, a power supply unit 42 for supplying an alternating current to the electrode 41, and between the power supply unit 42 and the electrode 41. It is the structure provided with the distribution line 45 to connect and the sealing parts 46a and 46b which make the side wall hole part of the storage means 1 which this distribution line 45 penetrates into an airtight state. The plasma generating means 4 has a configuration in which a space between the electrode 41 and the grounded storage means 1 is an impedance Z, and oxygen gas or oxygen radicals are generated by electrons moving through the impedance Z.

  Next, the operation of the plasma sterilization apparatus according to this embodiment based on the above configuration will be described. First, the adjustment valve 23 is opened and the rotary pump 21 is started, whereby the air in the storage means 1 is discharged, and the storage means 1 is in a predetermined low pressure state. In a state where the discharge by the adjustment valve 23 is continued, the adjustment valve 33 of the oxygen gas supply means 3 is opened, and oxygen gas is supplied from the oxygen gas cylinder 31 into the storage means 1 through the supply pipe 32.

An alternating current is supplied to the electrode 41 from the power supply unit 42 of the plasma generating means 4 in a state where the oxygen gas pressure in the storage means 1 becomes a predetermined value (for example, 3 Pa to 10 kPa). The alternating current causes the electrode 41 to generate an electromagnetic wave, and this electromagnetic wave generates oxygen gas (O ₂ ) into plasma (ionization) to generate oxygen ions (O ⁺ ) and electrons (e ⁻ ).

The generated electrons (e ⁻ ) collide with atoms of the oxygen gas (O ₂ ) in the storage means 1, and give high energy to the oxygen gas (O ₂ ) to generate oxygen radicals (O). . Since oxygen radicals are generated by electrons in which oxygen gas is turned into plasma in this way, the amount of oxygen radicals generated can be increased by increasing the plasma density, and the generated oxygen radicals can be used alone. In order to continue for a longer time, only oxygen gas is used as a raw material in the storage means 1 under a low pressure state.

In particular, in order to maximize the density of generated oxygen radicals (for example, 10 ¹⁰ cm ⁻³ ), the plasma generating means 4 has a power supply frequency of 13.56 MHz and a potential applied to the electrode 41 of −10V. And the discharge power consumption is 50 W. Further, the storage means 1 sets the internal oxygen gas pressure to 3 Pa and the oxygen gas flow rate to 10 sccm.
(Second embodiment of the present invention)
A plasma sterilization apparatus according to a second embodiment of the present invention will be described with reference to FIGS. 2 is a schematic configuration diagram of the plasma sterilization apparatus according to the present embodiment, and FIG. 3 is an operation timing chart of the plasma sterilization apparatus described in FIG.

  In each of the drawings, the plasma sterilization apparatus according to the present embodiment includes a storage means 1, a low-pressure maintaining means 2, an oxygen gas supply means 3, and a plasma generation means 4 as in the plasma sterilization apparatus according to the first embodiment. In addition to this configuration, the plasma generating unit 4 includes a frequency switching unit 43 that switches the frequency of the alternating current output to the electrode 41 between 10 kHz and 13.56 MHz, and the low pressure state of the storage unit 1 and oxygen gas supply It is the structure provided with the in-container condition control part 5 which controls a part.

  The frequency switching unit 43 supplies an alternating current with a frequency of 10 kHz to the electrode 41 at the beginning of activation, and after about one minute or two minutes from the start of activation, switches the frequency to 13.56 MHz and supplies the alternating current to the electrode 41. It is the structure to do. The in-container condition control unit 5 controls the suction amount of the rotary pump 21 by adjusting the opening degree of the adjustment valve 23 of the low pressure maintaining means 2 and adjusts the opening degree of the adjustment valve 33 of the oxygen gas supply means 3. Thus, the flow rate of the oxygen gas supplied from the oxygen gas cylinder 31 to the storage means 1 is controlled between 10 sccm and 500 sccm.

  Next, the operation of the plasma sterilization apparatus according to this embodiment based on the above configuration will be described. First, the rotary valve 21 is driven by controlling the adjustment valve 23 to be fully open based on the control of the in-container condition control unit 5. Further, the rotary pump 21 is driven to depressurize the storage means 1 to a predetermined low atmospheric pressure (for example, 3 Pa), and the adjustment valve 33 of the oxygen gas supply means 3 is opened in this low atmospheric pressure state via the supply pipe 32. Control is performed so that oxygen gas is supplied from the oxygen gas cylinder 31 to the storage means 1.

  While oxygen gas is being supplied to the storage means 1, the low pressure maintaining means 2 continues to discharge from the storage means 1, and the balance between the supply of oxygen gas and the discharge from the storage means 1 is continued. By adjusting the in-container condition control section 5, the oxygen gas pressure in the storage means 1 can be controlled to a desired value.

  Thus, in a state where the oxygen gas pressure in the storage means 1 is adjusted, the alternating current from the power supply unit 42 is switched to the frequency 10 kHz by the frequency switching unit 43 and output to the electrode 41. Since the oxygen gas in the storage means 1 at the time of start-up has a large impedance impedance Z characteristic, this 10 kHz low frequency alternating current can be easily impedance-matched with respect to the large impedance Z. The oxygen gas in the means 1 can be rapidly and reliably transferred to a predetermined plasma density.

  When the oxygen gas in the storage means 1 reaches this predetermined plasma density, the frequency switching unit 43 switches the frequency of the alternating current supplied to the electrode 41 to a high frequency of 13.56 MHz to further promote the oxygen gas plasmaization. As a result, the plasma density can be further increased and the density of generated oxygen radicals can be controlled to a maximum.

  Further, the in-container condition control unit 5 adjusts the opening of the adjustment valve 23 of the low pressure maintaining means 2 and the adjustment valve 33 of the oxygen gas supply means 3 to thereby adjust the oxygen gas 3Pa in the storage means 1 and the storage means. The state of oxygen gas flow rate 10 sccm to 1 is continued for 5 minutes, then the state of oxygen gas pressure 10 kPa in the storage means 1 and the state of oxygen gas flow rate 500 sccm to the storage means 1 are continued for 5 minutes. Run cyclically for 90 minutes (see FIG. 3).

In this way, the oxygen radical density is controlled to be maximized, the oxygen gas pressure is changed from 3 Pa to 10 kPa, and the oxygen gas flow rate is cyclically switched from 10 sccm to 500 sccm at intervals of 5 minutes. Oxygen radicals can penetrate into the fine parts and the mounting lower surface of the medical device, and can be reliably and easily sterilized over the entire region of the medical device.
(Third embodiment of the present invention)
A plasma sterilization apparatus according to a third embodiment of the present invention will be described based on FIG. This FIG. 4 shows the see-through | perspective structure diagram in the storage means in the plasma sterilization apparatus which concerns on this embodiment.

  In the same figure, the plasma sterilization apparatus according to this embodiment is provided with a storage means 1, a low-pressure maintaining means 2, an oxygen gas supply means 3, and a plasma generation means 4 in common as in the first and second embodiments. The arrangement configuration of the electrodes 41 in the plasma generating means 4 is different. The electrode 41 is arranged in the storage means 1 so as to cross a plurality of opening regions of the connector 34 connecting the supply pipe 32 of the oxygen gas supply means 3, and oxygen gas supplied through the supply pipe 32 is supplied to the electrode 41. It is configured to pass very close.

Next, the operation of the plasma sterilization apparatus according to this embodiment based on the above configuration will be described. As in each of the above embodiments, the state of the atmospheric pressure and oxygen gas in the storage means 1 is adjusted, the alternating current supplied from the power supply unit 42 flows to the electrode 41, and an electromagnetic field is generated around the line as the antenna of the electrode 41. Let The oxygen gas supplied from the supply pipe 32 can be forcibly passed through the very vicinity of the conductive wire of the electrode 41 having a strong magnetic field intensity, and the plasma generation of the oxygen gas is further promoted by the strong electromagnetic field. Can do.
(Other embodiments of the present invention)
The plasma sterilization apparatus according to another embodiment of the present invention has various configurations similar to the above embodiments, and in addition to the various configurations, oxygen radicals pass through the object to be processed stored in the storage means 1, Since sterilization is performed in a state of being covered with a sheet that does not allow bacteria to permeate, such as a micromesh sheet, it is possible to prevent external bacteria from re-adhering even when taken out from the storage means 1 after the process. Can do.

  Further, in the plasma sterilization apparatus according to another embodiment of the present invention, the second embodiment is configured to adjust the oxygen gas pressure and the oxygen gas flow rate of the storage means 1 respectively. It is also possible to configure so that only one of these is adjusted and controlled.

1 is a schematic configuration diagram of a plasma sterilization apparatus according to a first embodiment of the present invention. It is a schematic block diagram of the plasma sterilization apparatus which concerns on the 2nd Embodiment of this invention. It is an operation | movement timing chart of the plasma sterilization apparatus of FIG. It is a see-through | perspective block diagram in the storage means in the plasma sterilization apparatus which concerns on the 3rd Embodiment of this invention. It is a schematic structure sectional view of the conventional plasma sterilizer. It is a schematic structure sectional view of the conventional plasma sterilizer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Storage means 2 Low pressure maintenance means 3 Oxygen gas supply means 4 Plasma generation means 5 In-vessel condition control part 21 Rotary pump 22 Discharge pipes 23 and 33 Adjustment valve 24 and 34 Connector 31 Oxygen gas cylinder 32 Supply pipe 41 Electrode 42 Power supply part 43 Frequency switching part 45 Distribution line 46a, 46b Sealing part Z Impedance

Claims (9)

A storage means for storing an object to be sterilized, an airtight container,
Low pressure maintaining means for maintaining the atmospheric pressure in the storage means at a low pressure;
Oxygen gas supply means for supplying oxygen gas to the storage means;
A plasma sterilization apparatus comprising: at least an electrode housed in the housing means; and plasma generating means for generating an oxygen radical by causing a current to flow through the electrode to turn oxygen of the oxygen gas into plasma. In the plasma sterilization apparatus according to claim 1,
The plasma sterilizer characterized in that the low-pressure maintaining means maintains the inside of the storage container at 3 Pa to 10 kPa. In the plasma sterilization apparatus according to claim 1 or 2,
The plasma sterilizer characterized in that the low-pressure maintaining means changes the pressure of the oxygen gas in the airtight container of the storage means a plurality of times from 3 Pa to 10 kPa. In the plasma sterilization apparatus according to any one of claims 1 to 3,
The plasma sterilization apparatus, wherein the low pressure maintaining means repeatedly changes the pressure of oxygen gas in the airtight container of the storage means between 3 Pa and 10 kPa every 1 to 10 minutes. In the plasma sterilization apparatus according to any one of claims 1 to 4,
The plasma sterilization apparatus, wherein the plasma generation means is constituted by inductively coupled plasma generation means. In the plasma sterilization apparatus according to any one of claims 1 to 5,
The plasma sterilizer is characterized in that the plasma generating means is supplied with an alternating current to the electrode, and the frequency of the alternating current is set to 1 kHz to 20 kHz at the start and 10 MHz to 60 MHz after the start. In the plasma sterilization apparatus according to any one of claims 1 to 6,
The plasma sterilizer characterized in that the oxygen gas supply means changes the flow rate of the supplied oxygen gas a plurality of times between 10 sccm and 500 sccm. In the plasma sterilization apparatus according to any one of claims 1 to 6,
The plasma sterilizer characterized in that the oxygen gas supply means repeatedly changes the flow rate of the supplied oxygen gas between 10 sccm and 500 sccm every 1 to 10 minutes. In the plasma sterilization apparatus according to any one of claims 1 to 8,
A plasma sterilization apparatus, wherein an object to be processed stored in the storage means is coated with a sheet that transmits oxygen radicals.

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