Sterilization method and sterilization device

Abstract

This sterilization device (1) comprises: a first container (12) that accommodates an object (A01); a first decompression unit (14) that decompresses the first container; and a supply unit (15) that supplies a pernitric acid gas to the object placed under a decompressed condition provided by the first decompression unit. The sterilization device can sterilize deep portions of the object.

Description

Sterilization method and sterilization device

[0001] The present invention relates to a sterilization method and a sterilization device.

[0002] Sterilization technology is one of the fundamental technologies that support modern life. In this specification, "sterilization" means reducing the number of viable bacteria. Sterilization treatment targets a wide range of items, including medical instruments, food containers, and food.

[0003] As an example of the background art, there is a sterilization method using a pernitric acid solution, which has been proposed by the present inventors (see, for example, Patent Document 1). In this sterilization method, the pernitric acid solution is applied to an object to be sterilized.

[0004] Japanese Patent No. 6087029

[0005] However, some objects to be sterilized are difficult to reach with the pernitrate solution. Examples of such objects include medical instruments (e.g., syringes and tubes). Furthermore, medical instruments are sterilized in a container while being placed in a sterilization bag. Sterilization bags generally have a structure that makes it difficult for liquids such as pernitrate solution to pass through. Therefore, in the background art, it may be difficult to sterilize some objects to reach their depths.

[0006] An object of the present invention is to provide a sterilization method and a sterilization device that can sterilize deep portions of an object.

[0007] In the sterilization method according to the present invention, pernitric acid gas is supplied to an object placed under reduced pressure in a first container.

[0008] The sterilization apparatus of the present invention comprises a first container for accommodating an object, a first pressure reduction section for reducing the pressure in the first container, and a supply section for supplying pernitrate gas to the object placed under reduced pressure conditions by the first pressure reduction section.

[0009] According to the present invention, a sterilization method and a sterilization device capable of sterilizing deep parts of an object can be provided.

[0010] Fig. 1 is a diagram showing the configuration of a sterilizer according to an embodiment. Fig. 2 is a flow diagram of sterilization treatment by the sterilizer shown in Fig. 1. Fig. 3 is a diagram showing the configuration of a sterilizer according to a first modified example. Fig. 4 is a flow diagram of sterilization treatment by the sterilizer shown in Fig. 3. Fig. 5 is a diagram showing the configuration of a sterilizer according to a second modified example. Fig. 6 is a diagram showing the configuration of a sterilizer according to a third modified example. Fig. 7 is a perspective view showing the configuration of a discharge pipe. Fig. 8 is a diagram showing a schematic view of the flow of gas in the sterilizer.

[0011] Hereinafter, a sterilization method and a sterilization device according to an embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same or equivalent parts are designated by the same reference numerals, and the repeated description will be avoided.

[0012] In the sterilization method according to the embodiment, pernitrate gas is supplied to an object A01 (see FIG. 1) placed under reduced pressure in a first container 12 (see FIG. 1). Therefore, deep portions of the object A01 can be sterilized. Specifically, the half-life of pernitrate gas is longer under reduced pressure conditions than under other conditions. That is, reduced pressure conditions increase the lifespan of pernitrate gas. Therefore, the distance over which pernitrate gas can diffuse within the first container 12 before being thermally inactivated is increased. Therefore, even if the object A01 has a complex shape, deep portions of the object A01 can be sterilized by the pernitrate gas. Furthermore, because the reduced pressure increases the half-life of pernitrate gas, the concentration of pernitrate gas inside the first container 12 also becomes relatively higher. This improves the sterilizing power of pernitrate gas, achieving a powerful sterilization effect in a short period of time.

[0013] Fig. 1 is a diagram showing a sterilization apparatus 1 for carrying out a sterilization method. Fig. 2 is a flow chart of the sterilization treatment by the sterilization apparatus 1 shown in Fig. 1.

[0014] As shown in FIG. 1 , the sterilization apparatus 1 includes, as components, a housing 11, a first container 12, a door 13, a first pressure reduction section 14, a supply section 15, flow paths 16A and 16B, an atmosphere release port 16C, a first valve 17, an atmosphere release valve 18, and a control section 19.

[0015] The housing 11 includes an exterior body and a frame of the sterilization device 1 and houses the components excluding the door 13 .

[0016] The first container 12 can accommodate an object A01. The object A01 is an object to be sterilized by the sterilization device 1. A typical example of the object A01 is a medical instrument. Some medical instruments have a shape that makes it difficult for liquids such as pernitric acid solution to penetrate. A catheter is an example of this type of medical instrument. Another example of a medical instrument is a syringe. The medical instrument is also housed in the first container 12 in a sterilization bag A02. The sterilization bag A02 does not allow liquids such as pernitric acid solution to pass through. Therefore, it is difficult to sterilize the object A01 placed in the sterilization bag A02 with a pernitric acid solution. In addition to medical instruments, the object A01 can also be a wide variety of items such as food containers, food, and seeds.

[0017] Hereinafter, the term "object A01" includes the meaning of the object A01 itself and the meaning of the object A01 placed in the sterilization bag A02.

[0018] The first container 12 is typically a pressure container. A pressure container is designed to be able to store a substance at a pressure different from atmospheric pressure. The first container 12 has an opening 121 that opens in a predetermined direction. That is, the opening 121 is formed in the first container 12.

[0019] Door 13 is attached to housing 11 so that opening 121 can be opened and closed (see arrow A03). When door 13 is closed, it seals the inside of first container 12. When door 13 is open, an operator places object A01 in first container 12 or puts pernitric acid solution into reservoir 151 of supply unit 15 through opening 121.

[0020] The first decompression unit 14 reduces the pressure inside the first container 12. Specifically, under the control of the control unit 19, the first decompression unit 14 exhausts gas inside the first container 12, which is closed by the door 13, to the outside of the first container 12. Furthermore, under the control of the control unit 19, the first decompression unit 14 maintains the inside of the first container 12, which is closed by the door 13, in a reduced pressure state. The first decompression unit 14 is typically a vacuum pump.

[0021] The supply unit 15 supplies pernitrate gas to the object A01 placed under reduced pressure conditions by the first pressure reduction unit 14. Pernitrate gas has a relatively long half-life under reduced pressure conditions, and therefore can sterilize deep within the object A01.

[0022] In this embodiment, the supply unit 15 includes a storage unit 151, which is a bottomed container. The storage unit 151 is installed in the first container 12. The storage unit 151 has an opening 1511. The opening 1511 is open upward. The storage unit 151 stores a pernitrate solution. As a result, in the first container 12, the pernitrate solution evaporates, generating pernitrate gas directly above the opening 1511.

[0023] The flow path 16A connects the inside of the first container 12 with the first pressure reduction section 14. The flow path 16A is a pipe made of metal or resin, and connects the inside of the first container 12 with the first pressure reduction section 14 so that a fluid can flow between them. The flow path 16A is an example of the "first flow path" in the present invention.

[0024] The first valve 17 is a control valve provided on the flow path 16 A. The first valve 17 opens and closes the flow path 16 A under the control of the control unit 19.

[0025] The flow path 16B has an atmosphere vent port 16C at one end. The atmosphere vent port 16C is an opening that is open to the atmosphere. The flow path 16B is a pipe made of metal or resin. The other end of the flow path 16B is connected to the inside of the first container 12. The flow path 16B leads from the inside of the first container 12 to the atmosphere vent port 16C. A fluid can flow through the flow path 16B.

[0026] The atmosphere release valve 18 is a valve for releasing the pressure inside the first container 12 to the atmosphere. This makes it possible to increase the pressure inside the first container 12 with a simple configuration. More specifically, the atmosphere release valve 18 is a control valve that is provided in the flow path 181 and opens and closes the flow path 181 under the control of the control unit 19.

[0027] The control unit 19 includes a processor and a memory. The processor is a central processing unit or a microcomputer. The memory includes a read-only memory and a random access memory. The memory stores a computer program. The computer program defines the processing of the processor.

[0028] In the control unit 19, the processor executes a computer program. As a result, the control unit 19 repeatedly executes a first depressurization process 191, a leaving process 192, and an atmosphere opening process 193 in the order described (see FIG. 2 ). The first depressurization process 191 and the atmosphere opening process 193 are examples of the “depressurization step” and the “atmosphere opening step” of the present invention.

[0029] In this embodiment, one cycle is defined as a period from the start of one first depressurization process 191, through one leaving process 192, to the end of one atmosphere release process 193. Three cycles of the process are illustrated in FIG.

[0030] As a preliminary step to the first depressurization process 191, the operator opens the door 13 and then places the target object A01 in the first container 12. If necessary, the operator also pours a pernitrate solution into the storage section 151. The operator then closes the door 13 and causes the sterilization device 1 to perform a sterilization process (see FIG. 2 ). As shown in FIG. 2 , the sterilization process includes the first depressurization process 191, a leaving process 192, and an atmosphere opening process 193.

[0031] 1 and 2, in first decompression process 191, so-called "vacuum drawing" is performed. Specifically, control unit 19 opens first valve 17, closes atmosphere release valve 18, and decompresses first container 12 using first decompression unit 14. Within first container 12, pernitrate gas is generated by evaporation above opening 1511. Furthermore, first container 12 is filled with pernitrate gas, and as a result, pernitrate gas is supplied to sterilization bag A02 by supply unit 15. Because the pernitrate gas is a gas, it passes through sterilization bag A02, enters sterilization bag A02, and reaches object A01.

[0032] Furthermore, because the first decompression treatment 191 places the first container 12 under reduced pressure, the half-life of the pernitrate gas is lengthened. Therefore, the distance over which the pernitrate gas can diffuse within the first container 12 before being thermally inactivated is extended. As a result, the pernitrate gas is more likely to reach deeper portions of the object A01. In this way, the sterilization device 1 is capable of sterilizing deep portions of the object A01. Furthermore, the longer half-life increases the concentration of the pernitrate gas within the first container 12. This improves the sterilization power of the pernitrate gas, thereby achieving a powerful sterilization effect in a short period of time.

[0033] In addition, in order to suppress evaporation of water from the pernitrate solution by the first decompression treatment 191, it is preferable to set the pressure inside the first container 12 to a value higher than the saturated vapor pressure of water (for example, approximately 0.02 atmospheres at 20°C).

[0034] The control unit 19 transitions to a standing process 192 on the condition that a first time T01 (i.e., evacuation time) has elapsed since the start of the first depressurization process 191. Note that this condition may also be that the degree of vacuum in the first container 12 reaches a predetermined threshold. In the standing process 192, the control unit 19 closes the first valve 17 and stops the first depressurization unit 14 while keeping the atmosphere release valve 18 closed. The control unit 19 transitions to an atmosphere opening process 193 on the condition that a second time T02 (i.e., standing time) has elapsed since the start of the standing process 192. Note that the standing process does not have to be executed. That is, in the sterilization process, a direct transition from the first depressurization process 191 to the atmosphere opening process 193 may be made. In this case, the second time T02 is zero.

[0035] In the atmosphere release process 193, a so-called "vacuum break" is performed. Specifically, the control unit 19 opens the atmosphere release valve 18 to release the inside of the first container 12 to the atmosphere. Preferably, the control unit 19 opens the atmosphere release valve 18 while closing the first valve 17 and stopping the operation of the first pressure reducing unit 14. As a result, the atmosphere is introduced into the first container 12, causing a pressure fluctuation within the first container 12, and the pernitrate gas above the opening 1511 moves within the first container 12. Accordingly, a gas with a relatively low pressure occupied by the pernitrate gas is supplied above the opening 1511. This promotes evaporation of the pernitrate solution in the storage unit 151, and new pernitrate gas is generated above the opening 1511. Therefore, the sterilization ability of the sterilization device 1 is maintained for a long period of time.

[0036] The first decompression process 191 extends the half-life of the peroxynitrate gas. The diffusion of this peroxynitrate gas within the first container 12 enables sterilization deep within the object A01. However, some objects A01 have portions that are difficult to sterilize, such as "thin tubes with sealed ends." In order to sterilize such objects A01, in this embodiment, the first decompression process 191 and the atmosphere release process 193 are repeated multiple times, resulting in a fluid flow within the first container 12.

[0037] However, in the case of pernitrate gas, when the first container 12 is opened to the atmosphere by the atmosphere opening process 193, the half-life time of the pernitrate gas shortens as the pressure increases. As a result, the sterilization ability of the pernitrate gas is lost in a short time. In this embodiment, in order to maintain the sterilization ability of the pernitrate gas for a long period of time, the sterilization device 1 periodically repeats the first decompression process 191 to fill the first container 12 with pernitrate gas under reduced pressure conditions. With exhaust using a general vacuum pump, the time required for the atmosphere opening process 193 is approximately the same as the half-life time of the pernitrate gas. Therefore, it is preferable to repeatedly perform the first decompression process 191, the leaving process 192, and the atmosphere opening process 193 immediately after introducing outside air into the first container 12 by the atmosphere opening process 193.

[0038] In addition, peroxynitrate gas has the property that its bactericidal activity is easily inactivated by heat under conditions of increased pressure. However, in this embodiment, by repeating the first decompression treatment 191 and the atmosphere exposure treatment 193 multiple times, the peroxynitrate gas having the above property can effectively reach deep inside the target object A01.

[0039] In the atmosphere release process 193, it is preferable that the flow path 16B is supplied so that a jet of air from the flow path 16B hits the liquid surface of the pernitrate solution in the storage portion 151. This makes it possible for the air introduced into the first container 12 to contain a sufficient amount of pernitrate gas above the opening 1511 of the storage portion 151. As this mixed gas diffuses within the first container 12, the first container 12 is filled with pernitrate gas under reduced pressure conditions. As a result, the sterilization ability of the sterilization device 1 is improved.

[0040] Furthermore, the pernitric acid gas is generated by evaporation of the pernitric acid solution, so that salts are not released from the pernitric acid solution into the first container 12. This prevents contamination of the object A01.

[0041] There are several methods for producing a pernitrate solution, but it is generally produced by mixing a nitrous acid solution with a hydrogen peroxide solution under acidic conditions. Nitrite solution can be made from a nitrite (e.g., sodium nitrite) and nitric acid, so pernitrate solution is produced by adding a nitrite solution dropwise to a solution obtained by mixing a hydrogen peroxide solution with a nitric acid solution. In this case, the pernitrate solution may contain a nitrate (e.g., sodium nitrate) as a salt.

[0042] 1, it is preferable to additionally place an absorbent 1512 made of paper or polymer fibers on the liquid surface of the pernitrate solution in the reservoir 151. The absorbent 1512 is more preferably in sheet form. The absorbent 1512 absorbs the pernitrate solution by capillary action. This increases the area of ​​the pernitrate solution that is in direct contact with the gas above the opening 1511. As a result, evaporation of the pernitrate solution is further promoted. Therefore, the absorbent 1512 can also be considered an evaporation promoter.

[0043] The control unit 19 transitions to the first decompression process 191 on the condition that a third time T03 (i.e., break time) has elapsed since the start of the atmosphere opening process 193. The fourth time T04, which is the sum of the second time T02 and the third time T03, is determined based on the half-life time of the pernitrate gas. Therefore, the first decompression process 191 is repeated at a period based on the half-life time of the pernitrate gas. By repeating the first decompression process 191 at a period based on the half-life time, the sterilization ability of the sterilization device 1 is maintained. Note that if the first decompression process 191 is repeated at a period much longer than the half-life time, the sterilization ability of the pernitrate gas may be lost due to thermal inactivation. Even if such pernitrate gas can reach deep within the object A01, it cannot sterilize the deep within the object A01.

[0044] The formula for calculating the half-life of peroxynitrate gas is given in the references below.

[0045] [References] Richard A. Graham, Arthur M. Winer, and James N. Pitts Jr., The Journal of Chemical Physics "Pressure and temperature dependence of the unimolecular decomposition of HO2NO2" (USA), 1978, Vol. 68, p. 4505. According to the above formula, for example, the half-life of nitric acid gas under conditions of 1 atmosphere and 4.55 degrees (277.7 K) is approximately 97 seconds. Also, under conditions of 1 atmosphere and 24.85 degrees (298 K), the half-life is approximately 12 seconds. Note that the half-life of nitric acid gas also depends on the pressure under reduced pressure conditions.

[0046] Generally, the half-life of peroxynitrate gas is shorter than the half-life of peroxynitrate solution. Therefore, if the fourth time is much longer than the half-life or first time T01, the peroxynitrate gas will not reach the depths of the object A01. Therefore, it is not preferable that the fourth time be excessively longer than the half-life or first time T01.

[0047] The inventors conducted the following experiment to confirm the effects of the sterilization method and sterilization device 1 according to the embodiment.

[0048] The inventor prepared the following three types of Teflon (registered trademark) tubes, A, B, and C. Each of tubes A to C is 1 / 8 inch (inner diameter 1.59 mm, outer diameter 3.17 mm). The lengths of tubes A, B, and C are 100 cm, 300 cm, and 500 cm.

[0049] The inventor connected syringes to each of tubes A to C and placed biological indicators (manufactured by MesaLabs, model number HMV-091) into the syringes. Biological indicators (hereinafter referred to as "BIs") are used to evaluate the effectiveness of sterilization devices. BIs have a structure in which a carrier coated with bacterial spores is wrapped in nonwoven fabric. Of liquid droplets and gas, only gas can pass through the nonwoven fabric. Therefore, if the bacteria inside the BI are sterilized, it can be determined that the sterilization was achieved by gas. Materials such as Tyvek (registered trademark), which have good permeability to pernitrate gas, are suitable for the nonwoven fabric used in the sterilization bag and BI.

[0050] The inventors evaluated the sterilization ability of the sterilizer 1 using biological indicators installed in tubes A to C, with a first time T01 (vacuuming time) of 1 minute, a second time T02 (standing time) of 1 minute, and a third time T03 (break time) of 1 minute. The first container 12 was depressurized to 0.1 atm by the first depressurization process 191. Air at 0.9 atm was introduced into the first container 12 by the atmosphere opening process 193. The sterilizer 1 repeated three cycles of the first depressurization process 191, standing time process 192, and atmosphere opening process 193. As a result, all biological indicators were less than 30 CFU (Colony Forming Unit). In other words, the inventors confirmed that the sterilizer 1 achieved sterilization in a total of 9 minutes.

[0051] Fig. 3 is a diagram showing the configuration of a sterilizer 2 according to a first modified example. Fig. 4 is a flow diagram of the sterilization process performed by the sterilizer 2 shown in Fig. 3.

[0052] As shown in Figure 3, compared to the sterilization apparatus 1 (see Figure 1), the sterilization apparatus 2 further includes a second container 21, flow paths 22A and 22B, a second valve 23, a second pressure reduction section 24, and a third valve 25.

[0053] The second vessel 21 may be a pressure vessel having the same specifications as the first vessel 12 .

[0054] The flow path 22A connects the inside of the first container 12 and the inside of the second container 21. The flow path 22A is a pipe made of metal or resin, and connects the inside of the first container 12 and the inside of the second container 21 so that a fluid can flow between them. The flow path 22A is an example of the "second flow path" in the present invention.

[0055] The second valve 23 is a control valve provided on the flow path 22 A. The second valve 23 opens and closes the flow path 22 A under the control of the control unit 19.

[0056] The second decompression unit 24 reduces the pressure inside the second container 21. Specifically, the second decompression unit 24 discharges gas inside the second container 21 to the outside of the second container 21 under the control of the control unit 19. Furthermore, the second decompression unit 24 maintains the inside of the second container 21 in a reduced pressure state under the control of the control unit 19. The second decompression unit 24 is typically a vacuum pump. Note that the second decompression unit 24 may be the vacuum pump that constitutes the first decompression unit 14.

[0057] The flow path 22B connects the inside of the second container 21 with the second pressure reduction section 24. The flow path 22B is a pipe made of metal or resin, and connects the inside of the second container 21 with the second pressure reduction section 24 so that a fluid can flow between them. The flow path 22B is an example of the "third flow path" in the present invention.

[0058] The third valve 25 is a control valve provided on the flow path 22B. The third valve 25 opens and closes the flow path 22B under the control of the control unit 19.

[0059] As in the embodiment, a process preceding the first depressurization process 191 is performed by an operator. Then, the sterilization process is started by the sterilization device 2. As shown in Fig. 4, the sterilization process differs from the sterilization process shown in Fig. 2 in that a second depressurization process 291 and a valve opening process 292 are further performed.

[0060] 3 and 4, so-called "vacuum drawing" is performed in the second depressurization process 291. Specifically, the second depressurization process 291 is performed at a different timing from the first depressurization process 191. Therefore, the second depressurization process 291 is performed during the time period when the leaving process 192 and the atmosphere opening process 193 are performed.

[0061] Specifically, in the second decompression process 291, the control unit 19 opens the third valve 25 and reduces the pressure inside the second container 21 by the second decompression unit 24. In the second decompression process 201, it is preferable that the second valve 23 is closed.

[0062] The valve opening process 292 is executed by the control unit 19 during execution of the first depressurization process 191. It is preferable that the control unit 19 executes the valve opening process 292 between the start and end of execution of the first depressurization process 191. In the valve opening process 292, the control unit 19 opens the second valve 23. As a result, in the first depressurization process 191, the pressure inside the first container 12 is reduced relatively early.

[0063] FIG. 5 is a diagram showing the configuration of a sterilization device 3 according to a second modified example.

[0064] As shown in FIG. 5, the sterilization apparatus 3 differs from the sterilization apparatus 1 (see FIG. 1) in that it includes a supply unit 31 instead of the supply unit 15, the flow path 16B, and the atmospheric release valve 18.

[0065] The supply unit 31 is a bubbling device installed outside the first container 12. The supply unit 31 supplies pernitrate gas obtained by bubbling a pernitrate solution into the first container 12. The pernitrate gas diffuses within the first container 12, filling the first container 12 with pernitrate gas under reduced pressure conditions. Specifically, the supply unit 31 flows a carrier gas into a tank storing the pernitrate solution, supplying a mixed gas of the vaporized pernitrate solution (i.e., pernitrate gas) and the carrier gas into the first container 12. That is, outside air (i.e., carrier gas) is introduced into the first container 12 by the mixed gas. Furthermore, by aerating (bubbling) the outside air through the pernitrate solution, a mixed gas containing a large amount of pernitrate gas is introduced into the first container 12. This makes it possible for the air introduced into the first container 12 to contain a sufficient amount of pernitrate gas. As this mixed gas diffuses within the first container 12, the first container 12 is filled with pernitrate gas under reduced pressure conditions. As a result, the sterilization ability of the sterilization device 1 is improved.

[0066] The supply unit 31 may control the flow of the carrier gas by an electromagnetic valve or the like, or may control the flow of the carrier gas by a mass flow controller or the like.

[0067] Fig. 6 is a diagram showing the configuration of a sterilizer 4 according to a third modified example. Compared to the sterilizer 1 (see Fig. 1 ), the sterilizer 4 includes a supply unit 41 and a partition wall 42 instead of the supply unit 15.

[0068] The partition wall 42 is a wall that divides the interior of the first container 12. The partition wall 42 separates the space in which the target object A01 is placed from the space in which the supply unit 41 is placed. A portion of the partition wall 42 is open so that the space in which the target object A01 is placed and the space in which the supply unit 41 is placed are in communication with each other.

[0069] The supply unit 41 has a reservoir 151 for storing the pernitric acid solution and a discharge pipe 43. The supply unit 41 constitutes a bubbler.

[0070] The base end of the discharge pipe 43 is connected to the flow path 16B. The tip of the discharge pipe 43 is placed in the pernitrate solution in the storage section 151. The discharge pipe 43 is a pipe for introducing air (carrier gas) into the pernitrate solution to bubbling it. By supplying air bubbles into the pernitrate solution by bubbling, evaporation of the pernitrate solution is further promoted, and a gas containing a large amount of pernitrate gas can be obtained.

[0071] The container in which the supply unit 41 is placed and the container in which the target object A01 is placed may be separate vacuum containers connected to each other by a flow path. For example, the supply unit 31 in Fig. 5 is a bubbler.

[0072] 7 is a perspective view showing the configuration of the discharge pipe 43. The discharge pipe 43 has a trunk pipe 431, a first branch pipe 432a, and a second branch pipe 432b. Air from the flow path 16B is introduced into the upper part of the trunk pipe 431. The first branch pipe 432a is connected to the tip (lower part) of the trunk pipe 431, and the second branch pipe 432b is connected to the opposite side of the first branch pipe 432a.

[0073] The first branch pipe 432a and the second branch pipe 432b extend in the horizontal direction. The first branch pipe 432a has a plurality of outlets 433a on one side (the first direction side). The second branch pipe 432b has a plurality of outlets 433b on the other side (the side opposite the first direction). Air is discharged from the plurality of outlets 433a and the plurality of outlets 433b. The first branch pipe 432a and the second branch pipe 432b have cross-sectional shapes resembling airplane wings. For example, the first branch pipe 432a and the second branch pipe 432b have slopes facing diagonally upward on the first direction side and the side opposite the first direction.

[0074] The discharge pipe 43 discharges air from multiple discharge ports 433a and multiple discharge ports 433b in a horizontal, diagonally downward, or diagonally upward direction. Therefore, the discharged air bubbles create a horizontal flow in the pernitrate solution. This allows the bubbles to remain in the pernitrate solution for a longer period of time than when air is simply discharged downward or upward. This increases the concentration of pernitrate gas contained in the bubbles. Furthermore, because bubbling occurs under reduced pressure, the volume of air introduced into the supply section 41 increases significantly. To prevent the pernitrate solution from scattering and allow a large volume of air to pass through the pernitrate solution, a configuration in which air is discharged in a rotational direction, as with the discharge pipe 43, is preferred.

[0075] Furthermore, the multiple outlets 433a and the multiple outlets 433b discharge air in opposite directions. Therefore, the bubbles of the blown air create a rotating vortex flow in the pernitrate solution. This increases the time the bubbles remain in the pernitrate solution and promotes contact between the bubbles and the pernitrate solution. Furthermore, the first branch pipe 432a and the second branch pipe 432b have a cross-sectional shape resembling an airplane wing, making them less likely to obstruct the vortex flow of the pernitrate solution. For example, the main pipe 431 is positioned at the center of the reservoir 151 in a plan view.

[0076] The discharge pipe may have only one of the first branch pipe and the second branch pipe. The first branch pipe and the second branch pipe may each have one discharge port. The discharge pipe may be configured to create a flow in the pernitrate solution that rotates in a planar view. The storage section 151 may be cylindrical. The discharge port of the discharge pipe may be configured to discharge air in a circumferential direction (rotational direction) at a position away from the center of the storage section 151.

[0077] Since the space inside the first container 12 is divided by the partition 42, maintenance such as cleaning up splashes around the supply part 41 is easy.

[0078] FIG. 8 is a schematic diagram showing the gas flow in the sterilization apparatus. The configuration indicated by the reference numeral 801 corresponds to the sterilization apparatus 4. In the configuration indicated by the reference numeral 801, an atmosphere release valve 18 is provided between the supply unit 41 constituting the bubbler and the atmosphere. On the other hand, no valve is provided between the supply unit 41 and the object A01. The first container 12 containing the object A01 and the supply unit 41 is a vacuum container. During the first decompression treatment, the first valve 17 is open and the atmosphere release valve 18 is closed. Therefore, the space around the object A01 and the space around the pernitrate solution in the supply unit 41 are evacuated. Thereafter, the control unit 19 closes the first valve 17 and opens the atmosphere release valve 18. As a result, air is introduced into the pernitrate solution in the supply unit 41, causing it to bubble. The pernitrate gas generated in the supply unit 41 is supplied to the area around the object A01, the pressure of which has been previously reduced.

[0079] In the configuration indicated by the reference numeral 802, an atmosphere release valve 18 is provided between the supply unit 41 constituting the bubbler and the target object A01. While the first decompression treatment is being performed, the first valve 17 is open and the atmosphere release valve 18 is closed. Therefore, only the space around the target object A01 is evacuated. Thereafter, the control unit 19 closes the first valve 17 and opens the atmosphere release valve 18. At this time, the air above the pernitrate solution in the supply unit 41 is at atmospheric pressure. Therefore, the air that was originally remaining above the pernitrate solution first flows into the area around the target object A01, and then the pernitrate gas generated by bubbling flows into the area around the target object A01.

[0080] Therefore, the configuration indicated by reference numeral 801 can supply a higher concentration of peroxynitrate gas to the periphery of the object A01 from the initial stage than the configuration indicated by reference numeral 802.

[0081] Furthermore, in the configuration indicated by the reference numeral 802, depending on the shape of the object A01, air not containing pernitrate gas supplied first may remain around (or inside) the object A01, preventing the pernitrate gas supplied later from contacting the object A01. In order to sterilize microorganisms adhering to the surface of the object A01, it is necessary to ensure a period of time during which the surrounding air and the pernitrate gas supplied later can sufficiently mix by diffusion. This means that the concentration of the pernitrate gas, which has a short half-life, decreases during the period required for diffusion, and a sufficient concentration of pernitrate gas is not supplied to the outermost surface of the object A01 to which microorganisms are attached, lengthening the time required for sterilization.

[0082] In contrast, in the configuration shown by reference numeral 801, the air in the space above the pernitrate solution in the supply unit 41 is evacuated in advance, preventing air from accumulating around the target object A01. Therefore, the configuration shown by reference numeral 801 (the configuration of the sterilization device 4) is particularly excellent in sterilization performance.

[0083] To prevent this problem, the timing of opening and closing each valve may be changed in the configuration indicated by the reference numeral 802. For example, while the first depressurization process is being performed, the first valve 17 is open and the atmosphere release valve 18 is closed. Thereafter, the control unit 19 opens the atmosphere release valve 18 while leaving the first valve 17 open. As a result, the air above the pernitrate solution in the supply unit 41 is evacuated, and the air supplied around the target A01 is exhausted by the first depressurization unit 14. Thereafter, the control unit 19 closes the first valve 17. As a result, high-concentration pernitrate gas is supplied around the target A01.

[0084] The configuration indicated by reference numeral 803 further includes a fourth valve 44 in addition to the configuration indicated by reference numeral 802. The fourth valve 44 connects the first pressure reduction section 14 to the space above the pernitrate solution in the supply section 41. During the first pressure reduction process, the first valve 17 is open, the atmosphere release valve 18 is closed, and the fourth valve 44 is closed. The first valve 17 is then closed and the fourth valve 44 is opened. This allows the air above the pernitrate solution in the supply section 41 to be evacuated in advance. The control section 19 then opens the atmosphere release valve 18 and closes the fourth valve 44. This introduces air into the pernitrate solution in the supply section 41, and the pernitrate gas generated by bubbling flows around the target A01. The configuration indicated by reference numeral 803 also prevents air from accumulating around the target A01.

[0085] In the configurations indicated by the reference numerals 801, 802, and 803, multiple atmosphere release valves 18 may be provided in parallel instead of a single atmosphere release valve 18. If a large amount of air is suddenly supplied to the supply unit 41, which is a bubbler, immediately after the start of the atmosphere release process, the pernitrate solution may be splashed due to a water hammer phenomenon. Therefore, by opening the multiple atmosphere release valves 18 in stages, the impact can be alleviated and the splashing of the pernitrate solution can be suppressed. The control unit 19 may open the multiple atmosphere release valves 18 in stages depending on the pressure or time inside the first container 12.

[0086] Alternatively, some of the parallel-arranged atmospheric release valves 18 may be opened during the first decompression process. In this case, a small amount of pernitrate gas is supplied from the supply unit 41 to the space surrounding the object A01 during evacuation. The half-life of pernitrate gas is longer under low pressure. Therefore, it is useful to continue supplying pernitrate gas even during the first decompression process. Furthermore, in the configuration indicated by reference numeral 802, this prevents air (which has a low concentration of pernitrate gas) that has accumulated above the pernitrate solution from being supplied to the space surrounding the object A01 during the atmospheric release process.

[0087] The inventors conducted the following experiment to confirm the effects of the sterilization method and sterilization device 4 according to the embodiment.

[0088] A syringe was connected to a fluororesin tube. A biological indicator (MesaLabs, model number: HMV-091) was placed inside the syringe. The entire tube and syringe were placed inside a nonwoven fabric bag (sterilization bag) to form a PCD (process challenge device). The tube was 5 m long, had an inner diameter of 1.0 mm, and an outer diameter of 3.0 mm. Compared to similar PCDs, the tube was longer, contained more nonwoven fabric, and had higher sterilization resistance. The vacuum container containing the PCD had a capacity of 48 L.

[0089] In the sterilization device 4, one cycle consisted of one minute of the first decompression process (first valve 17 open, atmospheric release valve 18 closed) and one minute of the atmosphere release process (first valve 17 closed, atmospheric release valve 18 open). In the first decompression process, the pressure inside the vacuum container was reduced to 0.02 atm. In the atmosphere release process, air was introduced into the vacuum container until the pressure reached 1.0 atm. All PCDs in multiple experiments were sterilized (n=6, bacterial survival probability was 10 －６ ) was successfully achieved. In this way, the sterilization device 4 can sterilize deep inside an instrument having a long, narrow lumen, such as a catheter or an endoscope.

[0090] Furthermore, when a biological indicator (manufactured by MesaLabs, model number: HMV-091) was placed alone as a PCD in a vacuum container, sterilization (n=6) was achieved by one cycle (2 minutes) of treatment.

[0091] In addition, a carrier (SUS disk) coated with bacterial spores was removed from the nonwoven fabric of a biological indicator (manufactured by MesaLabs, model number: HMV-091), placed in a syringe connected to a tube, and the entire assembly was covered with a sterilization bag to form a PCD. When this PCD was placed in a vacuum container, it was successfully sterilized (n=6) after two cycles (4 minutes) of treatment.

[0092] The embodiments of the present disclosure have been described above with reference to the drawings. However, the present disclosure is not limited to the above-described embodiments and can be implemented in various forms without departing from the spirit and scope of the present disclosure. Furthermore, various disclosures can be formed by appropriately combining multiple components disclosed in the above-described embodiments or each modification. For example, some components may be omitted from all components shown in the embodiments or each modification. Furthermore, components across the embodiments and each modification may be appropriately combined. The drawings mainly show each component in a schematic manner to facilitate understanding. The thickness, length, number, spacing, etc. of each illustrated component may differ from the actual components due to the convenience of drawing. Furthermore, the materials, shapes, dimensions, etc. of each component shown in the above-described embodiments are merely examples and are not particularly limited. Various modifications are possible within a scope that does not substantially deviate from the effects of the present disclosure.

[0093] (1) In the embodiment, the atmosphere opening process 193 opens the first container 12 to the atmosphere through the atmosphere opening port 16C and the flow path 16B, thereby increasing the pressure inside the first container 12. However, this is not limited to this, and the pressure inside the first container 12 may be increased from a reduced pressure condition to a pressure other than atmospheric pressure. Specifically, the purpose of the atmosphere opening process 193 is to create a fluid flow inside the first container 12. Therefore, the pressure inside the first container 12 does not necessarily need to be returned to atmospheric pressure. Specifically, if outside air can be introduced into the first container 12 up to a certain pressure depending on the structure of the object A01, it is possible to prevent a decrease in the half-life time due to the increase in pressure.

[0094] Furthermore, the gas introduced into the first container 12 from outside during the atmosphere release process is not limited to air, but may be other gases such as nitrogen gas. In other words, "exposure to the atmosphere" is not limited to a process of increasing the pressure inside the first container 12 to atmospheric pressure, nor is it limited to a process of introducing air. "Exposure to the atmosphere" refers to a gas supply process of supplying gas into the first container 12 from outside to increase the pressure inside the first container 12.

[0095] (2) The first time T01, the second time T02, and the third time T03 may be times other than those described in the embodiment. Furthermore, the number of cycles of the first depressurization process 191, the leaving process 192, and the atmosphere opening process 193 may be other than three.

[0096] (3) Nitrous acid gas may be mixed into the first container 12. This allows recycling to occur within the first container 12, improving the stability of the pernitrate gas under reduced pressure conditions. Alternatively, pernitrate gas synthesized using activated species generated by plasma may be used.

[0097] (4) In the embodiment, the first decompression process 191 and the atmosphere opening process 193 rapidly open the first container 12, which is filled with peroxynitrate gas under reduced pressure conditions, to the atmosphere with a mixed gas containing peroxynitrate gas. As a result, peroxynitrate gas, which is unstable under atmospheric pressure conditions, is effectively supplied to the depths of the target object A01. However, it is not necessary to perform both the first decompression process 191 and the atmosphere opening process 193. In the sterilization device 1, it is sufficient to perform at least one of the first decompression process 191 and the atmosphere opening process 193.

[0098] (5) It is generally known that the sterilizing effect of chemical substances increases as the temperature increases, accelerating the chemical reaction. Therefore, by increasing the temperature in the first container 12, for example, by using a heater, before starting the sterilization process using the sterilization device 1, the sterilization process can be completed in a short time.

[0099] (6) The half-life of pernitrate gas is relatively long under reduced pressure conditions, but relatively short under atmospheric pressure conditions. Therefore, the sterilizing activity of pernitrate gas quickly disappears under atmospheric pressure conditions. In other words, the toxicity of pernitrate gas also quickly disappears under atmospheric pressure conditions. In sterilization methods using ethylene oxide gas and hydrogen peroxide gas, due to their high toxicity, it is necessary to remove the sterilizing components remaining in the equipment by aeration for several hours or more after the sterilization treatment. However, in sterilization methods using pernitrate gas, the toxicity of pernitrate gas quickly disappears under atmospheric pressure conditions, so aeration for a relatively long period of time is not required. Therefore, the sterilization device 1 according to this embodiment has very high industrial practicality.

[0100] The present invention is applicable to the sterilization of medical instruments, cell culture isolators, food containers, etc., and has industrial applicability.

[0101] DESCRIPTION OF SYMBOLS 1, 2, 3, 4: Sterilizer 11: Housing 12: First container 121: Opening 14: First pressure reduction section 15: Supply section 151: Storage section 1511: Opening 1512: Absorber 16A, 16B, 181, 22A, 22B: Flow path 16C: Atmospheric release port 17: First valve 18: Atmospheric release valve (gas supply valve) 19: Control section 21: Second container 23: Second valve 24: Second pressure reduction section 25: Third valve 31, 41: Supply section 43: Discharge pipe 433a, 433b: Discharge port

Claims

1. The process includes a depressurization step of reducing the pressure inside the first container so as to extend the half-life of the pernitrate gas, A sterilization method comprising supplying the pernitrate gas to an object placed under reduced pressure conditions in the first container.

2. The sterilization method according to claim 1, wherein the pressure is reduced to 0.1 atm or less in the pressure reduction step.

3. A gas supply step comprising supplying gas into the first container to supply the pernitrate gas to the object placed under reduced pressure conditions in the first container, The sterilization method according to claim 1 or 2, wherein the depressurization step and the gas supply step are repeated in sequence.

4. The sterilization method according to claim 3, wherein the depressurization step is repeated at a cycle based on the half-life of the pernitrate gas.

5. The first container is provided with a storage section for storing pernitrate solution. The sterilization method according to claim 3, wherein in the gas supply step, the gas is supplied toward the opening of the storage unit.

6. The sterilization method according to claim 5, wherein an absorbent that absorbs the pernitrate solution by capillary action is placed on the surface of the pernitrate solution in the storage section.

7. The sterilization method according to claim 1, wherein the pernitrate gas obtained by bubbling a pernitrate solution is supplied into the first container.

8. In the aforementioned depressurization step, the space above the pernitric acid solution is depressurized, The sterilization method according to claim 3, wherein the gas supply step involves bubbling by supplying gas into the pernitrate solution, and the resulting pernitrate gas is supplied to the target object.

9. A first container capable of containing the object, A first depressurization unit that depressurizes the first container so that the half-life of pernitrate gas is extended, A supply unit that supplies the pernitrate gas to the object placed under reduced pressure conditions by the first pressure reduction unit, and A sterilization device equipped with the following features.

10. The sterilization apparatus according to claim 9, wherein the first depressurization section reduces the pressure to 0.1 atm or less.

11. A first flow path connecting the inside of the first container and the first pressure reduction section, A first valve that opens and closes the first flow path, A gas supply valve for increasing the pressure inside the first container, Control unit and Equipped with, The control unit, A first depressurization process involves opening the first valve, closing the gas supply valve, and reducing the pressure inside the first container using the first depressurization unit, A gas supply process is performed by opening the gas supply valve and supplying gas into the first container. A sterilization apparatus according to claim 9 or 10, which performs the following:

12. The second container, A second channel connecting the inside of the first container and the inside of the second container, A second valve that opens and closes the second flow path, A second depressurization unit for reducing the pressure of the second container, A third channel connecting the inside of the second container and the second pressure reduction section, A third valve that opens and closes the third flow path and Furthermore, The control unit, The third valve is opened, and the second depressurization process is performed to reduce the pressure inside the second container using the second depressurization unit, During the execution of the first depressurization process, a valve opening process is performed in which the second valve is opened. The sterilization apparatus according to claim 11, further performing the above.

13. The supply unit has a storage unit for storing pernitrate solution, The first depressurization section depressurizes the space above the pernitrate solution in the storage section, The sterilization apparatus according to claim 9 or 10, wherein the supply unit performs bubbling by supplying gas into the pernitrate solution while the space above the pernitrate solution is under reduced pressure, and supplies the resulting pernitrate gas to the target object.

14. The sterilization apparatus according to claim 13, wherein the supply unit has a discharge port for discharging the gas in the circumferential direction at a position away from the center of the storage unit.