Non-thermal plasma cleaning device and cleaning method

Abstract

The non-thermal plasma cleaning device (12) includes a housing (16) including an input port (30) for fluid connection to a gas source, a radio wave source (18), and a controller (22) configured to continuously perform at least two, preferably at least three, non-thermal plasma generation cycles during the cleaning step. Each non-thermal plasma generation cycle includes controlling the radio wave source (18) to be in an active state for a first predetermined duration to generate non-thermal plasma in the housing (16), and controlling the radio wave source (18) to be in a non-active state for a second predetermined duration. The input port (30) is in an open state for at least the second predetermined duration.

Description

Technical Field

[0001] The present invention relates to - a housing for receiving at least one object to be cleaned, the housing including an input port for fluidly connecting the housing to a gas supply source, and - a radio wave source having an active state in which the radio wave source outputs electromagnetic waves and an inactive state in which the radio wave source does not output electromagnetic waves, the electromagnetic waves having a frequency in the radio wave range or the microwave range, the radio wave source being coupled to the housing such that in the active state, the electromagnetic waves propagate within the housing, a radio wave source and relates to a type of non-thermal plasma cleaning device including the same.

[0002] The present invention also relates to a cleaning assembly including such a non-thermal plasma cleaning device, as well as a cleaning method.

[0003] The present invention relates to cleaning using plasma, particularly in the field of cleaning medical supplies and medical devices.

Background Art

[0004] It is known to use plasma to sterilize objects. Examples thereof are disclosed in Patent Documents JP3813586B2 and US2022 / 001056A1.

[0005] The document "From patent to product? 50 years of low-pressure plasma sterilization" by Fiedrandt et al., Plasma Process Polymers, 2018 discloses a comprehensive overview of all research on non-thermal plasma sterilization and provides a detailed description of several techniques enabling the generation of non-thermal plasma for sterilization.

[0006] Patent Document EP2618851A1 also discloses a sterilization device using non-thermal plasma for sterilizing objects such as medical devices, i.e., implants.

[0007] "Non-thermal plasma" (also referred to as "low-temperature plasma" or "non-equilibrium plasma") means, in the context of the present invention, a plasma in which electrons and heavy species (ions and neutrals) are not in thermodynamic equilibrium with each other. In such a plasma, the temperature of the electrons (up to several tens of thousands of Kelvin) is typically significantly higher than the temperature of the heavy species, which is maintained near room temperature, i.e., ~50 °C, by adjusting the appropriate parameters of the plasma generation mechanism. The temperature to which an article such as a medical device is exposed when placed in such a non-equilibrium plasma phase is the temperature of the heavy species, i.e., near room temperature.

[0008] The sterilization device described above includes a sealed chamber for receiving the object to be sterilized, a vacuum pump for evacuating the chamber to a secondary vacuum, and an electron cyclotron resonance generator for generating microwaves and a magnetic field within the chamber. As a result of the magnetic field output by the generator, non-thermal plasma is ignited within the chamber, and the object placed within the chamber is sterilized.

[0009] However, such a device is not sufficient.

[0010] In fact, according to Regulation (EU) 2017 / 745, sterilization is considered effective when the number of contaminants has been reduced by at least one-tenth. Nevertheless, the duration required to achieve such a reduction using the device described above is unacceptably long. 6

[0011] Figure 1 shows, for illustration purposes, the time-course progression of the number of A) Gram-negative bacteria (Pseudomonas aeruginosa), B) Gram-positive bacteria (Staphylococcus aureus), and C) spores (Bacillus subtilis spores) during the implementation of the non-thermal plasma cleaning method by the device described above in oxygen, argon, and nitrogen for Gram-negative and Gram-positive bacteria, and in vacuum and oxygen for spores.

[0012] In fact, as can be seen from FIG. 1, the duration required to achieve such a reduction using the above-described device is about 1 hour in the case of Gram-negative bacteria (Pseudomonas aeruginosa, curve A) and 2 hours in the case of Gram-positive bacteria (Staphylococcus aureus, curve B), which is unacceptably long for commercial use. Furthermore, when using the above-described device, it has been shown that the reduction in the number of spores (Bacillus subtilis spores, curve C) does not reach a factor of 10 even after 2 hours. 6 The coefficient of

[0013] An object of the present invention is to provide a cleaning device that is more time-efficient than known plasma-based cleaning devices.

Summary of the Invention

[0014] For this purpose, the present invention is a non-thermal plasma cleaning device of the type described above, and the non-thermal plasma cleaning device A controller configured to control a radio wave source and an input port so as to continuously perform at least two, preferably at least three, non-thermal plasma generation cycles during the cleaning step Further includes, and each non-thermal plasma generation cycle During a first predetermined duration, by controlling the radio wave source to be in an active state, generating non-thermal plasma in the housing, After the first predetermined duration, during a second predetermined duration, controlling the radio wave source to be in an inactive state Including, The input port is in an open state to allow the flow of gas into the housing for at least the second predetermined duration, Each of the first predetermined duration and the second predetermined duration is strictly greater than zero.

[0015] In fact, the inventors have found that the reaction kinetics associated with plasma generation is such that the chemical species that most contribute to the decomposition of undesired chemical substances and / or pathogens (i.e., excited state radiation structures and / or molecules), hereinafter referred to as "reactants of interest", exist only in a very small part in the steady state compared to other less reactive species. In contrast, in the transient state, the proportion of reactants of interest is significantly higher. The transient state includes the first few minutes after plasma ignition, during which the concentration of reactive species develops rapidly. This is different from the steady state observed several minutes after the plasma phase is established, during which the concentration of reactive species is stable.

[0016] Therefore, the present invention proposes a treatment with non-thermal plasma generated periodically at regular intervals over a predetermined duration. Here, by performing a plurality of such non-thermal plasma generation cycles, defined as turning the non-thermal plasma on and off at two defined timings, and by enabling the flow of gas from the gas source to the housing during at least a second duration of each non-thermal plasma generation cycle, the reactants of interest that appear when the plasma is ignited are regenerated.

[0017] As a result, the present invention provides a much more efficient cleaning than that achieved with known non-thermal plasma cleaning devices.

[0018] According to another advantageous aspect of the present invention, the non-thermal plasma cleaning device includes one or more of the following features alone or in any possible combination.

[0019] The non-thermal plasma cleaning device may further include a pump fluidly connected to the housing, and the controller is configured to operate the pump such that the pressure inside the housing is below a predetermined threshold during at least one non-thermal plasma generation cycle.

[0020] The predetermined threshold may be less than 4000 Pa, preferably included in 0.5×10 -6 Pa to 400 Pa.

[0021] The radio wave source can be configured to have frequencies included in intervals in the range of 30 kHz to 300 MHz, particularly preferably, in the range of 6.765 MHz to 6.795 MHz, in the range of 13.553 MHz to 13.567 MHz, and / or in the range of 26.957 MHz to 27.283 MHz for at least one interval in the range of 30 kHz to 300 MHz.

[0022] Normally, the radio wave source can be configured to operate at a frequency adapted to the frequency of the housing 16, i.e., a frequency adapted to the natural frequency of the housing 16. Thereby, it is possible to reduce the return of additional waves in the electromagnetic waves for generating non-thermal plasma.

[0023] Alternatively, the radio wave source can be configured to have frequencies included in the range of 1 GHz to 5 GHz, preferably 2 GHz to 3 GHz, for example, a frequency equal to 2.45 GHz.

[0024] The first predetermined duration may be less than 5 minutes, preferably less than 3 minutes, advantageously less than 2 minutes, for example, less than 1 minute.

[0025] The second predetermined duration may be less than 5 minutes, preferably less than 3 minutes, advantageously less than 2 minutes, for example, less than 30 seconds.

[0026] The controller can be configured to continuously perform at least 5 non-thermal plasma generation cycles during the cleaning step.

[0027] The non-thermal plasma cleaning device may further include at least one sensor configured to output a sensing signal representing the temperature inside the housing, and the controller is further configured to control the radio wave source to be in an inactive state when the temperature determined based on the sensing signal is higher than a predetermined maximum value.

[0028] The present invention also relates to a cleaning assembly including a gas supply source and a non-thermal plasma cleaning device as defined above, the gas supply source being fluidly connected to an input port of the housing to supply gas to the housing of the non-thermal plasma cleaning device.

[0029] According to another advantageous aspect of the present invention, the cleaning assembly includes one or more of the following features, either alone or in any possible combination.

[0030] The gas supply source may be configured to supply a gas including at least one of air, nitrogen, oxygen, argon, and helium.

[0031] The gas supply source and the input port of the housing may be sized such that a predetermined amount of gas is injected into the housing during a second predetermined duration.

[0032] The present invention also relates to placing at least one object to be cleaned in the housing; continuously performing at least two, preferably at least three, non-thermal plasma generation cycles, each non-thermal plasma generation cycle including generating non-thermal plasma in the housing by controlling the radio frequency source to be active for a first predetermined duration; after the first predetermined duration, controlling the radio frequency source to be inactive for a second predetermined duration, and injecting a gas flow into the housing for at least the second predetermined duration; and a non-thermal plasma cleaning method comprising: in the active state, the radio frequency source outputs electromagnetic waves, in the inactive state, the radio frequency source does not output electromagnetic waves, the electromagnetic waves have a frequency in the radio wave range or the microwave range, and the radio frequency source is coupled to the housing such that electromagnetic waves propagate in the housing in the active state; each of the first predetermined duration and the second predetermined duration is strictly greater than zero, and also relates to a non-thermal plasma cleaning method.

[0033] According to another advantageous aspect of the present invention, the cleaning method further includes reducing the pressure inside the housing to less than a predetermined threshold value before at least one non-thermal plasma generation cycle.

[0034] The present invention is more appropriately understood with reference to the accompanying drawings.

Brief Description of the Drawings

[0035]

Figure 1

Figure 2

Figure 3

Figures 4 - 5

Embodiments for Carrying Out the Invention

[0036] A cleaning assembly 8 according to the present invention is shown in FIG. 2.

[0037] "Cleaning" means sterilization, disinfection, and / or decontamination of an object or surface in the context of the present invention.

[0038] "Sterilization" means, in the context of the present invention, the complete or nearly complete removal of biological burden (bacteria, spores, viruses, or proteins). More precisely, according to the ISO 14937 standard, sterilization of an object corresponds to reducing the biological burden on the object to at least 10 6 to the power of minus one. In other words, a medical device is considered sterilized when the probability of contamination is less than one in a million.

[0039] "Disinfection" means, in the context of the present invention, the incomplete removal of biological burden. More precisely, disinfection of an object corresponds to reducing the biological burden to 10 4 to 10 6 to the power of minus one. In other words, a medical device is considered disinfected when the probability of contamination is between one in ten thousand and one in a million.

[0040] "Decontamination" means, in the context of the present invention, reducing (i.e., dividing) the biological burden on an object to less than 10 4 to the power of minus one. Decontamination may also refer to the at least partial removal of active and harmful molecules such as toxins, fertilizers, pesticides, or chemical warfare agents (e.g., in the case of CBRN defense) present on a surface or in an object.

[0041] The cleaning assembly 8 includes a gas source 10 and a non-thermal cleaning device 12 (hereinafter referred to as the "cleaning device") fluidly connected to the gas source 10.

[0042] The cleaning device 12 is configured to receive the object 14 to be cleaned and perform the cleaning of the object 14.

[0043] The object 14 may be a reusable medical device such as, for example, a surgical instrument, a robotic arm or part thereof, an endoscope or part thereof, etc., but not limited thereto, or a disposable medical device such as, for example, an implant, a custom-made surgical instrument, a disposable endoscope part, etc., but not limited thereto.

[0044] Furthermore, the gas source 10 is configured to supply the cleaning device 12 with a gas, more particularly a gas suitable for generating a non-thermal plasma within the cleaning device 12 .

[0045] Preferably, the gas supplied by the gas source 10 is air. Alternatively, the gas supplied by the gas source 10 includes nitrogen, oxygen, argon, helium, and / or any combination thereof. The use of such species is advantageous because they are largely harmless to the user and do not leave behind dangerous reactive chemical residues after use. This is particularly advantageous because known sterilization techniques using chemicals such as ethylene oxide or hydrogen peroxide leave residues that can be harmful to patients after use. For example, the use of ethylene oxide is banned in the EU and subject to restrictions in the United States.

[0046] Additionally, gases such as air, nitrogen, oxygen, argon, and helium are traditionally available and affordable in a hospital environment, thereby reducing the cost of sterilization.

[0047] Cleaning devices 12

[0048] As described above, the cleaning device 12 is configured to receive and effect cleaning of the object 14 .

[0049] The cleaning device 12 includes a housing 16, a radio wave source 18, such as a radio frequency generator, and a controller 22. Preferably, the cleaning device 12 further includes a pump 24.

[0050] The housing 16 is intended to receive at least one object 14. Furthermore, the housing 16 is fluidly connected to a pump 24. The housing 16 is also coupled to a radio wave source 18. Furthermore, the controller 22 is configured to control the operation of the radio wave source 18, and preferably the operation of the housing 16 and / or the pump 24.

[0051] "Radio waves" means electromagnetic waves having frequencies below 300 GHz.

[0052] Housing 16

[0053] The housing 16 includes an inner wall 26 that defines an internal cavity 28 for receiving the object 14. The housing 16 also includes, for example, a door (not shown) for accessing the internal cavity 28 to place the object 14. The housing 16 further includes an input port 30 and an output port 32 to allow the inflow and outflow of gas to and from the internal cavity 28.

[0054] The housing 16 further includes at least one sensor 34 configured to measure a predetermined physical property within the internal cavity 28.

[0055] Advantageously, the inner wall 26 is at least partially made of a material suitable for a high-vacuum process, such as aluminum or stainless steel, and preferably a plasma-resistant material.

[0056] In the context of the present invention, "plasma-resistant material" means a material that is not degraded by plasma, i.e., a material that does not lose mass and / or thickness and / or oxidize to the extent that its physical and / or mechanical properties are affected over a predetermined total service life of the cleaning device 12.

[0057] Preferably, the dimensions of the inner wall 26 are selected to withstand a pressure within the internal cavity 28 that is less than 4000 Pa, preferably 0.5×10 -6 Pa to 400 Pa, i.e., within the range from low vacuum to high vacuum, without undergoing irreversible deformation.

[0058] More preferably, the housing 16 is configured such that when the door is closed during the cleaning step disclosed in more detail below, fluid can flow into and out of the internal cavity 28 only through the input port 30 and / or the output port 32.

[0059] Each of the input port 30 and the output port 32 may have an open position and a closed position for allowing or blocking the flow of gas between the internal cavity 28 and the external environment of the housing 16, respectively.

[0060] Each sensor 34 is configured to output a sensed signal representing the current value of a corresponding physical property within the internal cavity 28. For example, such a physical property is the pressure or temperature within the internal cavity 28.

[0061] Radio wave source 18

[0062] The radio wave source 18 is configured to output an electromagnetic wave 36, more specifically, a radio wave source.

[0063] More precisely, the radio wave source 18 has an active state and an inactive state. In the active state, the radio wave source 18 outputs the electromagnetic wave 36. Conversely, in the inactive state, the radio wave source 18 does not output an electromagnetic wave.

[0064] More precisely, in the active state, the radio wave source 18 is coupled to the housing 16 such that the electromagnetic wave 36 propagates within the housing 16, specifically within the internal cavity 28.

[0065] The electromagnetic wave 36 has a frequency in the radio wave range or the microwave range.

[0066] Advantageously, the radio wave source 18 is configured such that the electromagnetic wave 36 has a frequency included in one or more of the LF band (or "low frequency band", in the range of 30 kHz to 300 kHz), the MF band (or "medium frequency band", in the range of 300 kHz to 3 MHz), and the HF and VHF bands (or "high frequency bands", in the ranges of 3 MHz to 30 MHz and 30 MHz to 300 MHz).

[0067] Such a frequency range offers several advantages compared to the spectra of other frequency ranges. In fact, electromagnetic waves in the UHF band (the "ultra-high frequency band", in the range of 300 MHz to 3 GHz) have wavelengths close to the characteristic wavelengths of the materials placed inside the housing. Therefore, due to the energy transfer from the electromagnetic waves to the gas inside the housing, the materials placed inside the housing can be rapidly heated, and their physical properties and integrity may be affected.

[0068] Furthermore, the UHF band has conventionally been used for wireless / telecommunication, which brings a very high risk of interference with other devices, and thus may pose electromagnetic compatibility problems, especially in a medical environment.

[0069] For example, the radio wave source 18 is configured such that the electromagnetic wave 36 has a frequency belonging to a range that conforms to a standard ISM (Industrial, Scientific, and Medical) device using a frequency band harmonized by the ITU (International Telecommunication Union). Such a suitable frequency range is -6.78 MHz ± 15 kHz (i.e., 6.765 MHz to 6.796 MHz), -13.56 MHz ± 7 kHz (i.e., 13.553 MHz to 13.567 MHz), and -27.12 MHz ± 163 kHz (i.e., 26.957 MHz to 27.283 MHz) is.

[0070] Such a frequency range promotes electromagnetic compatibility in a medical environment.

[0071] Alternatively or additionally, especially in the case of the object 14 that is less sensitive to interference, the radio wave source 18 is configured such that the electromagnetic wave 36 has a frequency included in the microwave range, i.e., 300 MHz to 300 GHz. For example, the radio wave source 18 is configured such that the electromagnetic wave 36 has a frequency included in 1 GHz to 5 GHz, preferably 2 GHz to 3 GHz, for example, a frequency equal to 2.45 GHz.

[0072] The position of the radio wave source 18 relative to the housing 16 and the output power of the radio wave source 18 are selected so as to control the radio wave source 18 to be in an active state and cause non-thermal plasma ignition in the internal cavity 28 when appropriate pressure and gas composition are realized in the internal cavity 28. Examples of techniques for generating non-thermal plasma implemented in sterilization are described in the literature "From patent to product? 50 years of low-pressure plasma sterilization" Fiedrandt et al., Plasma Process Polymers, 2018.

[0073] Controller 22

[0074] As described above, the controller 22 is configured to control the operation of the radio wave source 18.

[0075] More precisely, the controller 22 is configured to continuously perform at least two, preferably at least three, non-thermal plasma generation cycles during the cleaning step for cleaning the object 14. In this example, the controller 22, during each non-thermal plasma generation cycle, - is in an active state for a first predetermined duration, - is in an inactive state for a second predetermined duration following the first predetermined duration so as to be configured to control the radio wave source 18.

[0076] Each of the first predetermined duration and the second predetermined duration is strictly greater than zero.

[0077] As a result, when appropriate pressure and gas composition are realized in the internal cavity 28, non-thermal plasma is generated in the housing 16, thereby bringing about the cleaning of the object 14.

[0078] Furthermore, the input port 30 is in an open state for a second predetermined duration to enable the flow of gas from the gas source 10 into the housing 16, more precisely into the internal cavity 28. Optionally, the input port 30 may be in an open state also during a first predetermined duration or a part thereof during which the radio wave source is in an active state.

[0079] For example, the controller 22 is configured to control the position of the input port 30 such that the input port 30 is in an open state during the second predetermined duration and, optionally, during at least a part of the first predetermined duration. Alternatively, the input port 30 is in a permanently open position and does not require control from the controller 22.

[0080] According to the present invention, a much more efficient cleaning is achieved than that associated with known non-thermal plasma cleaning. In fact, the inventors have found that the reaction kinetics involved in plasma generation are such that the chemical species (i.e., excited radiative structures and / or molecules) that most contribute to the decomposition of undesired chemicals and / or pathogens, hereinafter referred to as "reactants of interest", are present only in a very small part in the steady state compared to other less reactive species. In contrast, in the transient state, the proportion of reactants of interest is significantly higher.

[0081] Therefore, by performing such a non-thermal plasma generation cycle a plurality of times and enabling the flow of gas from the gas source into the housing during at least a predetermined second duration of each non-thermal plasma generation cycle, the reactants of interest that appear when the plasma is ignited are regenerated, thereby providing the cleaning device according to the present invention with improved cleaning performance.

[0082] Furthermore, the ignition of the plasma within the internal cavity 28 itself yields much better results than those achieved with known devices that perform cleaning using afterglow discharges (also referred to as "plasma beam cleaning").

[0083] In fact, when performing plasma beam cleaning, the gas flow passes through the discharge region and plasma is ignited. The plasma is then transported to the object to be cleaned located at a position distant from the discharge region. However, the inventors have discovered that the reactants of interest described above include reactants having a very short lifespan. As a result, by the time the plasma reaches the object to be cleaned, the reactants of interest have almost completely undergone chemical changes and thus lost their efficiency. In contrast, according to the present invention, the plasma is ignited around the object 14 to be cleaned, and the problems caused by the transport of the plasma are overcome.

[0084] Preferably, for each non-thermal plasma generation cycle, the first predetermined duration is less than 5 minutes, preferably less than 3 minutes, advantageously less than 2 minutes, for example less than 1 minute.

[0085] In fact, as described above, the reactants of interest are a mixture containing reactants having a short lifespan, and increasing the first duration beyond a certain time (typically part of the lifespan of the reactants of interest) does not bring great advantages.

[0086] Preferably, the controller 22 is configured to continuously perform at least 2, particularly at least 3, preferably at least 5 non-thermal plasma generation cycles during the cleaning step.

[0087] Furthermore, for each non-thermal plasma generation cycle, the second predetermined duration is less than 5 minutes, preferably less than 3 minutes, advantageously less than 2 minutes, for example less than 30 seconds.

[0088] In fact, since cleaning is not achieved due to the absence of plasma during the second duration, the second duration should be as short as possible. This is due to the fact that when the radio wave source 18 is switched to the inactive state, the plasma in the housing 16 rapidly disappears (within a few seconds, generally less than 5 seconds).

[0089] Advantageously, the input port 30 is sized such that during the above-mentioned predetermined second duration, a predetermined amount of gas is injected into the housing 16, more specifically into the internal cavity 28. By way of example, the amount of gas injected is greater than or equal to the amount of gas present in the internal cavity 28 during the first duration, preferably at least three times that amount, for example at least ten times that amount. In other words, the input port 30 is sized such that during a second predetermined duration, the gas in the internal cavity 28 is refreshed prior to the next non-thermal plasma generation cycle.

[0090] The flow rate of the pump 24 may be optimized together with the input port 30 such that during a second predetermined duration, the gas in the internal cavity 28 is refreshed prior to the next non-thermal plasma generation cycle.

[0091] For example, if the flow rate of dioxin is 1 scmm (standard cubic centimeter per minute), the pressure in the internal cavity is 10 -4 mbar (millibar), the temperature of the gas at the input port is 273.15 K (Kelvin), and the volume of the internal cavity 28 is 10 L, the second predetermined duration can be as short as 5 seconds.

[0092] As described above, the controller 22 is also configured to operate the pump 24. More precisely, the controller 22 is configured to control the pump 24 such that during at least one non-thermal plasma generation cycle, the pressure within the housing falls below a predetermined threshold value.

[0093] Preferably, the predetermined threshold value is less than 4000 Pa, preferably included in the range of 0.5×10 -6 Pa to 400 Pa.

[0094] Advantageously, the controller 22 is configured to operate the pump 24 based on a sensed signal output by one or more sensors 34, more precisely based on the pressure within the housing 16 (i.e., within the internal volume 28) derived from the sensed signal.

[0095] Advantageously, the controller 22 is configured to operate the radio wave source 18 based on a sensed signal output by one or more sensors 34, and more precisely based on the temperature of the object 14 derived from the sensed signal. For example, the controller 22 is configured to control the radio wave source 18 such that the radio wave source 18 is in an inactive state when the temperature of the object 14 exceeds a predetermined maximum value. As a result, heat-related degradation of the object 14 is prevented.

[0096] Operation

[0097] Here, the operation of the cleaning assembly 8 will be described.

[0098] During the sterilization step, the cleaning device 12 is connected to the gas supply source 10. Further, the controller 22 is configured such that, for example, a first duration and a second duration are stored in the controller. The controller 22 may be configured to store measurements of important parameters of the cycle for process control, regulation, and safety, including but not limited to the type of gas supplied by the gas supply source, and / or the number of non-thermal plasma generation cycles performed during the cleaning step, and / or the enclosure pressure, gas flow rate, radio wave power.

[0099] Next, in an initial step, at least one object 14 to be cleaned is placed within the enclosure 16, and more precisely within the internal cavity 28 of the enclosure 16.

[0100] The enclosure is closed, and preferably, the pressure within the enclosure 16 (i.e., within the internal cavity 28) is brought below a predetermined threshold using, for example, an optional pump 24 connected to the output port 32 of the enclosure 16.

[0101] Next, during the cleaning step, the controller 22 performs at least two, and preferably at least three, non-thermal plasma generation cycles continuously based on, for example, the type of gas supplied by the gas supply source 10 and / or the number of non-thermal plasma generation cycles to be performed that were previously stored.

[0102] As described above, during each non-thermal plasma generation cycle, the controller 22 - During a first predetermined duration, by being in an active state, generates non-thermal plasma within the housing 16, - During a second predetermined duration following the first predetermined duration, is in an inactive state to control the radio wave source 18 as such.

[0103] Furthermore, during the second predetermined duration, a gas flow is injected into the housing 16. In other words, during the second predetermined duration, the position of the input port 30 enables gas to flow from the gas supply source into the housing 16. In some cases, the gas flow may be injected into the housing 16 over a part or all of the first predetermined duration.

[0104] Next, in the storage step, each washed object 14 is stored within a corresponding package.

[0105] Alternatively, as shown in FIG. 3, the object 14 to be washed is provided within a corresponding package 40.

[0106] In this case, the package 40 can be considered as a housing, and is provided with an input port 42 connectable to the gas supply source 10 and an output port 44 connectable to the external environment, for example via a pump 24.

[0107] For convenience, a frame 44 coupled to the radio wave source 18 is provided, the package 40 is disposed within the frame 44, and when the radio wave source 18 is in an active state, electromagnetic waves propagate within the package 40 to enable the ignition of non-thermal plasma.

[0108] In this case, after the washing step, instead of having to put the object 14 into another sealable bag for storage purposes, the package containing the washed object 14 is removed from the frame and sealed.

[0109] Example

[0110] The above-described cleaning assembly was implemented in comparative experiments related to the treatment of spores, particularly Bacillus subtilis spores.

[0111] For this purpose, 10 6 Bacillus subtilis spores were prepared on a 2 cm × 8 cm glass sample from a Liophilchem spore suspension appropriately diluted before spreading on the support. In the post-treatment, the samples were recovered by sonication, vortexing, and filtration, and then from the filters exposed on the gel for UFC numbering.

[0112] The cleaning assembly 8 was implemented with the following settings. - Pressure inside the housing 16: in the range of 3×10 -4 mBar to 1×10 -4 mBar, - Frequency and power of the electromagnetic wave: 13.56 MHz to 100 W, - Electromagnetic flow density: 0 Gauss to 10 Gauss, - Gas inside the housing 16: 1 sscm of oxygen.

[0113] Figure 4 shows various types of exposure to non-thermal plasma, namely, - Continuous exposure to non-thermal plasma, - Discontinuous exposure to non-thermal plasma where the radio wave source is "on", i.e., active, for a first predetermined duration of 5 minutes and "off", i.e., inactive, for a second duration of 5 minutes, - Discontinuous exposure to non-thermal plasma where the radio wave source is "on" for a first predetermined duration of 5 minutes and "off" for a second duration of 3 minutes, - Discontinuous exposure to non-thermal plasma where the radio wave source is "on" for a first predetermined duration of 3 minutes and "off" for a second duration of 3 minutes, - Discontinuous exposure to non-thermal plasma where the radio wave source is "on" for a first predetermined duration of 2 minutes and "off" for a second duration of 2 minutes, - Discontinuous exposure to non-thermal plasma where the radio wave source is "on" for a first predetermined duration of 2 minutes and "off" for a second duration of 1 minute shows the progress of the number of Bacillus subtilis spores (on a logarithmic scale) as a function of time.

[0114] As the duration of exposure to non-thermal plasma increases (i.e., as the first predetermined duration increases), it can be seen that the time required to achieve a 10 6 division of the number of spores on object 14 actually becomes longer.

[0115] More specifically, on the condition that the first duration is longer than the lifetime of the reactant of interest, it is actually the number of cycles that affects the cleaning efficiency. This is clear from FIG. 5 which shows the progress of the number of Bacillus subtilis spores (on a logarithmic scale) as a function of the non-thermal plasma generation cycles due to the duration of exposure to non-thermal plasma described above. In other words, the cleaning efficiency depends on the time during which object 14 is exposed to the reactant of interest.

[0116] FIG. 4 and FIG. 5 also show that the sequential control of the generation of non-thermal plasma by the cycles described above reduces the biological load more linearly than known sterilization where non-thermal plasma is continuously generated.

[0117] In another example, the cleaning assembly 8 was implemented on 10 6 Bacillus subtilis spores on the glass sample described above with the following settings. - Pressure inside the housing 16: 2×10 -4 mBar, - Frequency and power of the electromagnetic wave: 13.56Mhz ~ 100W, - Electromagnetic flux density: 0 Gauss ~, - Gas inside the housing 16: 1 sscm of oxygen.

[0118] Table 1 below shows the results of various discontinuous exposures to non-thermal plasma according to cycles each having an "on" period of a first predetermined duration of 2 minutes and an "off" period of a second duration of 1 minute when the radio wave source is in an active state. [Table 1]

[0119] The cleaning assembly 8 was implemented for 10 6 Bacillus subtilis spores on the glass sample described above. - Pressure inside the housing 16: in the range of 3×10 -4 mBar~, - Frequency and power of the electromagnetic wave: 13.56Mhz~100W, - Electromagnetic flow density: 0 Gauss~, - Gas inside the housing 16: 1 sscm of oxygen.

[0120] The following Table 2 shows the results of various discontinuous exposures to non-thermal plasma according to a cycle having a first predetermined duration "on" period of 2 minutes and a second duration "off" period of 1 minute when the radio wave source is in an active state. [Table 2]

[0121] The cleaning assembly 8 was implemented for 10 6 Bacillus subtilis spores on the glass sample described above. - Pressure inside the housing 16: in the range of 3×10 -4 mBar~, - Frequency and power of the electromagnetic wave: 13.56Mhz~200W, - Electromagnetic flow density: 0 Gauss~, - Gas inside the housing 16: 1 sscm of oxygen.

[0122] The following Table 3 shows the results of various discontinuous exposures to non-thermal plasma according to a cycle having a first predetermined duration "on" period of 2 minutes and a second duration "off" period of 1 minute when the radio wave source is in an active state. [Table 3]

Claims

1. A sterilization assembly comprising a gas supply source (10) and a non-thermal plasma sterilization device (12), wherein the non-thermal plasma sterilization device (12) - A housing (16) for receiving at least one object to be sterilized, the housing (16) including an input port (30) for fluidly connecting the housing to a gas supply source, - A radio source (18) having an active state in which it outputs electromagnetic waves (36) and an inactive state in which it does not output electromagnetic waves (36), wherein the electromagnetic waves (36) have a frequency in the radio wave range or microwave range, and the radio source (18) is coupled to the housing (16) such that the electromagnetic waves (36) propagate within the housing (16) in the active state, - Controller (22), The number of non-thermal plasma generation cycles is at least two, preferably at least three. First duration and second duration for each non-thermal plasma generation cycle The controller is configured to store the radio wave source (56) and the input port (30) to perform a number of non-thermal plasma generation cycles in succession during the cleaning step, and each non-thermal plasma generation cycle is By controlling the radio wave source (18) to be in the active state for a first predetermined duration, a non-thermal plasma is generated within the housing (16), After the first predetermined duration, the radio wave source (18) is controlled to be in the inactive state for a second predetermined duration. A controller (22) and Includes, The input port (30) is left open for at least the second predetermined duration to allow gas to flow into the housing. Each of the first predetermined duration and the second predetermined duration is strictly greater than zero. The gas supply source (10) is fluidly connected to the input port (30) of the housing (16) of the non-thermal plasma sterilization device (12) to supply gas to the housing, and the gas supply source (10) is configured to supply a gas comprising at least one of air, nitrogen, oxygen, argon, and helium. Sterilized assembly.

2. The non-thermal plasma sterilization assembly according to claim 1, wherein the gas supply source (10) and the input port (30) of the housing (16) are sized such that a predetermined amount of gas is injected into the housing (16) during the second predetermined duration, the predetermined amount being at least equal to the amount of gas present in the housing (16) during the first duration, preferably at least three times that amount, for example, at least ten times that amount.

3. The non-thermal plasma sterilization assembly according to claim 1, wherein the non-thermal plasma sterilization device (12) further includes a pump (24) fluidly connected to the housing (16), and the controller (22) is configured to operate the pump (24) such that the pressure inside the housing (16) is below a predetermined threshold for at least one non-thermal plasma generation cycle.

4. The predetermined threshold is less than 4000 Pa, preferably 0.5 × 10 －６ A non-thermal plasma sterilization assembly according to claim 3, comprising ~400 Pa.

5. The radio wave source (18) emits electromagnetic waves (36) Frequencies included in the interval between 30 kHz and 300 MHz, particularly preferably, The range is 6.765 MHz to 6.795 MHz. The range of 13.553 MHz to 13.567 MHz, and / or Range of 26.957 MHz to 27.283 MHz The non-thermal plasma sterilization assembly according to claim 1, configured to have frequencies within the range of 30 kHz to 300 MHz in at least one interval.

6. The non-thermal plasma sterilization assembly according to claim 1, wherein the radio wave source (18) is configured such that the electromagnetic wave (36) has a frequency equal to a frequency in the 1 GHz to 5 GHz range, preferably 2 GHz to 3 GHz range, for example, 2.45 GHz.

7. The non-thermal plasma sterilization assembly according to claim 1, wherein the first predetermined duration is less than 5 minutes, preferably less than 3 minutes, advantageously less than 2 minutes, for example less than 1 minute.

8. The non-thermal plasma sterilization assembly according to claim 1, wherein the second predetermined duration is less than 5 minutes, preferably less than 3 minutes, advantageously less than 2 minutes, for example less than 30 seconds.

9. The non-thermal plasma sterilization assembly according to claim 1, wherein the controller (22) is configured to perform at least five non-thermal plasma generation cycles continuously during the cleaning step.

10. A non-thermal plasma sterilization assembly according to any one of claims 1 to 9, further comprising at least one sensor (34) configured to output a sensing signal representing the temperature inside the housing (16), wherein the controller (22) is further configured to control the radio wave source (18) to the inactive state if the temperature determined based on the sensing signal is higher than a predetermined maximum value.

11. A non-thermal plasma sterilization method for implementing a non-thermal plasma sterilization assembly according to any one of claims 1 to 9, wherein the non-thermal plasma sterilization method is: The steps include placing at least one object to be sterilized inside the housing (16), The step of performing at least two, preferably at least three, non-thermal plasma generation cycles in succession, wherein each non-thermal plasma generation cycle is: The method involves generating a non-thermal plasma within the housing (16) by controlling the radio wave source (18) to remain in an active state for a predetermined duration, Controlling the radio wave source (18) to be inactive for a second predetermined duration after the first predetermined duration, wherein a gas flow is injected into the housing for at least the second predetermined duration. Steps and Includes, In the active state, the radio source (18) outputs electromagnetic waves (36), and in the inactive state, the radio source (18) does not output electromagnetic waves (36), the electromagnetic waves (36) have a frequency in the radio wave range or microwave range, and in the active state, the radio source (18) is coupled to the housing (16) so that the electromagnetic waves (36) propagate within the housing (16). Each of the first predetermined duration and the second predetermined duration is strictly greater than zero. Non-thermal plasma sterilization method.

12. The non-thermal plasma sterilization method according to claim 11, further comprising reducing the pressure inside the housing (16) to below a predetermined threshold before at least one non-thermal plasma generation cycle.

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