Non-thermal plasma cleaning equipment and cleaning method

Abstract

A non-thermal plasma cleaning device (12) comprising:-a housing (16) comprising an input port (30) for fluid connection with a gas supply; a radio wave source (18); -a controller (22) configured to successively perform at least two, preferably at least three, non-thermal plasma generation cycles during the cleaning step, each generation cycle comprising: controlling the radio wave source (18) in an active state for a first predetermined duration to generate a non-thermal plasma in the enclosure (16); and controlling the radio wave source (18) to be in an inactive state during a second predetermined duration, the input port (30) to be in an open state at least during the second predetermined duration.

Description

Technical Field

[0001] The present invention relates to a non-thermal plasma cleaning device, which comprises:

[0002] - a housing for receiving at least one object to be cleaned, the housing comprising an input port for fluidly connecting the housing to a gas supply;

[0003] - a radio wave source having an active state and an inactive state, wherein in the active state the radio wave source outputs electromagnetic waves, and in the inactive state 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 in the housing.

[0004] The present invention also relates to a cleaning assembly comprising such a non-thermal plasma cleaning device, and a cleaning method.

[0005] The present invention relates to the field of cleaning using plasma, and in particular to the cleaning of medical supplies and instruments. Background Art

[0006] The use of plasma to sterilize objects is known, and examples thereof are disclosed in JP 3813586 B2 and US 2022 / 001056 A1.

[0007] The publication “From patent to product? 50 years of low-pressure plasma sterilization”, Fiedrandt et al., Plasma Process Polymers, 2018, discloses an overview of all research on non-thermal plasma sterilization and provides a detailed description of several technologies that can generate non-thermal plasma for sterilization.

[0008] Document EP 2 618 851 A1 also discloses a sterilization device for sterilizing objects (eg medical devices, ie implants) using non-thermal plasma.

[0009] In the context of the present invention, "non-thermal plasma" (also known as "cold plasma" or "non-equilibrium plasma") refers to 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 tens of thousands of Kelvin) is much higher than the temperature of the heavy species (which is typically maintained near room temperature, i.e., -50°C, by adjusting appropriate parameters of the plasma generation setup). The temperature to which an item, such as a medical device, placed in such a non-equilibrium plasma phase is exposed is the temperature of the heavy species and is therefore near room temperature.

[0010] The sterilization apparatus includes a sealed chamber for accommodating objects to be sterilized, a vacuum pump for performing a secondary vacuum treatment on the chamber, and an electron cyclotron resonance generator for generating microwaves and a magnetic field within the chamber. The electromagnetic field output by the generator ignites a non-thermal plasma within the chamber, sterilizing the objects placed within.

[0011] However, this device is not entirely satisfactory.

[0012] In fact, according to Regulation (EU) 2017 / 745, if the amount of pollutants is divided by at least 10 6 However, the duration required to achieve this reduction using the above-mentioned equipment is unacceptably long.

[0013] For illustrative purposes, Figure 1 Shown is the evolution over time of the number of A) Gram-negative bacteria, B) Gram-positive bacteria, and C) spores during the non-thermal plasma cleaning method for Gram-negative bacteria (Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus) in vacuum, oxygen, argon, and nitrogen, and during the non-thermal plasma cleaning method for spores (Bacillus subtilis spores) in vacuum and oxygen using the above-mentioned apparatus.

[0014] In fact, in Figure 1 As can be seen in the graph, the duration required to achieve such a reduction using the above-mentioned device is approximately one hour for Gram-negative bacteria (Pseudomonas aeruginosa, curve A) and approximately two hours for Gram-positive bacteria (Staphylococcus aureus, curve B), which is unacceptably long for commercial use. Furthermore, it has been demonstrated that, even after two hours, the reduction in the number of spores (Bacillus subtilis spores, curve C) using the above-mentioned device never reaches 10 6 .

[0015] It is an object of the present invention to provide a cleaning device which is more time-efficient than known plasma-based cleaning devices. Summary of the Invention

[0016] To this end, the present invention is a non-thermal plasma cleaning device of the above type, wherein the non-thermal plasma cleaning device also includes:

[0017] a controller configured to control the radio wave source and the input port to perform at least two, preferably at least three, non-thermal plasma generation cycles in succession during the cleaning step, each non-thermal plasma generation cycle comprising:

[0018] - controlling the radio wave source to be active during a first predetermined duration to generate a non-thermal plasma in the enclosure; and

[0019] - after the first predetermined duration, controlling the radio wave source to be inactive for a second predetermined duration,

[0020] the input port being open during at least a second predetermined duration to allow gas to flow into the housing;

[0021] Each of the first predetermined duration and the second predetermined duration is strictly greater than zero.

[0022] In fact, the inventors have discovered that the reaction dynamics associated with plasma generation are such that the chemical species that contribute most to the degradation of undesirable chemicals and / or pathogens (i.e., free radicals and / or molecules in an excited state) (hereinafter referred to as "reactants of interest") are present in very small quantities in the steady state compared to other less reactive species. In contrast, in the transient state, the proportion of the reactants of interest increases significantly. The transient state encompasses the first few minutes after the plasma is ignited, during which the concentration of the reactive species evolves rapidly. This is distinct from the steady state, which is observed a few minutes after the plasma phase is established, during which the concentration of the reactive species is stable.

[0023] Thus, the present invention proposes to perform treatment by generating a non-thermal plasma at regular intervals for a predetermined duration in a periodic manner. By performing a plurality of such non-thermal plasma generation cycles (defined herein as turning the non-thermal plasma on and off during two determined time periods), and by allowing gas to flow from the gas supply to the enclosure during at least the second duration of each non-thermal plasma generation cycle, the reactants of interest present when the plasma is ignited are regenerated.

[0024] Thus, the present invention provides a more efficient cleaning apparatus than known non-thermal plasma cleaning apparatuses.

[0025] According to further advantageous aspects of the invention, the non-thermal plasma cleaning device comprises one or more of the following features, which can be present alone or in any possible combination.

[0026] The non-thermal plasma cleaning apparatus may further include a pump fluidly connected to the housing, the controller being configured to operate the pump such that a pressure within the housing is below a predetermined threshold during at least one non-thermal plasma generation cycle.

[0027] The predetermined threshold value may be lower than 4000 Pa, preferably 0.5x10 -6 Pa to 400Pa.

[0028] The radio wave source may be configured such that the electromagnetic waves have a frequency comprised in the interval 30 kHz to 300 MHz, in particular in the range 30 kHz to 30 MHz, preferably in at least one of the following intervals:

[0029] The range is from 6.765MHz to 6.795MHz;

[0030] range from 13.553 MHz to 13.567 MHz; and / or

[0031] The range is from 26.957MHz to 27.283MHz.

[0032] Typically, the radio wave source can be controlled to operate at an adapted frequency, ie a frequency suitable for the natural frequency of the housing 16. This makes it possible to reduce the return of additional waves in the electromagnetic waves used to generate the non-thermal plasma.

[0033] Alternatively, the radio wave source may be configured such that the frequency of the electromagnetic waves is 1 GHz to 5 GHz, preferably 2 GHz to 3 GHz, for example equal to 2.45 GHz.

[0034] 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.

[0035] 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.

[0036] The controller may be configured to sequentially perform at least five non-thermal plasma generation cycles during the cleaning step.

[0037] The non-thermal plasma cleaning device may further include at least one sensor configured to output a sensing signal representing a temperature within the housing, and the controller may be further configured to control the radio wave source to an inactive state if the temperature determined based on the sensing signal is greater than a predetermined maximum value.

[0038] The invention also relates to a cleaning assembly comprising a gas supply and a non-thermal plasma cleaning apparatus as defined above, the gas supply being fluidly connected to an input port of a housing for providing gas to the housing of the non-thermal plasma cleaning apparatus.

[0039] According to other advantageous aspects of the invention, the cleaning assembly comprises one or more of the following features, alone or in any possible combination.

[0040] The gas supply device may be configured to supply a gas including at least one of air, nitrogen, oxygen, argon, and helium.

[0041] The gas supply and the input port of the housing may be sized such that a predetermined amount of gas is injected into the housing during the second predetermined duration.

[0042] The present invention also relates to a non-thermal plasma cleaning method comprising the following steps:

[0043] placing at least one object to be cleaned in the housing; and

[0044] At least two, preferably at least three, non-thermal plasma generation cycles are performed successively, each non-thermal plasma generation cycle comprising:

[0045] controlling the radio wave source to be activated for a first predetermined duration to generate a non-thermal plasma in the enclosure; and

[0046] After the first predetermined duration, the radio wave source is controlled to be in an inactive state for a second predetermined duration, and the gas flow is injected into the housing for at least the second predetermined duration,

[0047] wherein, in an activated state, the radio wave source outputs electromagnetic waves, and in an inactivated state, 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 activated state, the electromagnetic waves propagate in the housing,

[0048] Each of the first predetermined duration and the second predetermined duration is strictly greater than zero.

[0049] According to another advantageous aspect of the present invention, the cleaning method further comprises: prior to the at least one non-thermal plasma generation cycle, bringing the pressure within the enclosure below a predetermined threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The present invention will be better understood with reference to the accompanying drawings, in which:

[0051] Figure 1is a graph showing the evolution over time of the number of contaminants (logarithmic scale) on a surface cleaned using a known non-thermal plasma sterilization device;

[0052] Figure 2 is a schematic diagram of a first embodiment of a cleaning assembly according to the present invention;

[0053] Figure 3 is a schematic diagram of a second embodiment of a cleaning assembly according to the present invention;

[0054] Figure 4 and Figure 5 Provides implementation Figure 2 The results of the comparative experiment of cleaning components to treat spores, Figure 4 shows that the use of non-thermal plasma at different exposure durations Figure 2 the evolution over time of the number of spores (logarithmic scale) on the surface cleaned by the cleaning assembly, and Figure 5 shows that the use of non-thermal plasma at different exposure durations Figure 2 Evolution of the number of spores (logarithmic scale) on a surface cleaned by a cleaning assembly as a function of the non-thermal plasma generation period. DETAILED DESCRIPTION

[0055] The cleaning assembly 8 according to the present invention is Figure 2 Shown in.

[0056] "Cleaning" in the context of the present invention means sterilizing, disinfecting and / or decontaminating an object or surface.

[0057] "Sterilization" in the context of the present invention means the complete or almost complete removal of bioburden (bacteria, spores, viruses or proteins). More precisely, according to ISO 14937, sterilization of an object corresponds to dividing the bioburden on the object by at least 10 6 In other words, a medical device is considered sterile when the probability of contamination is less than one in a million.

[0058] "Disinfection" in the context of the present invention does not mean the complete removal of the bioburden. More precisely, disinfecting an object corresponds to dividing the bioburden on that object by 10 4 to 10 6 In other words, a medical device is considered sterile when the probability of contamination is between one in a million and one in ten thousand.

[0059] "Decontamination" in the context of the present invention means reducing (i.e. dividing) the bioburden on an object by 10 4Decontamination may also refer to the at least partial removal of active and harmful molecules present on a surface or object, such as toxins, fertilizers, pesticides or chemical warfare agents (e.g. in the context of CBRN defense).

[0060] The cleaning assembly 8 includes a gas supply 10 and a non-thermal cleaning device 12 (hereinafter referred to as “cleaning device”) fluidly connected to the gas supply 10 .

[0061] The cleaning device 12 is configured to receive an object 14 to be cleaned and is configured to clean the object 14 .

[0062] Object 14 can be a reusable medical device, such as but not limited to a surgical tool, a robotic arm or parts thereof, an endoscope or parts thereof, or a disposable medical device, such as but not limited to an implant, a customized surgical tool, a disposable endoscope part, etc.

[0063] Furthermore, the gas supply arrangement 10 is configured to provide a gas to the cleaning apparatus 12 , and more particularly, to provide a gas suitable for generating a non-thermal plasma within the cleaning apparatus 12 .

[0064] Preferably, the gas provided by the gas supply device 10 is air. Alternatively, the gas provided by the gas supply device 10 includes nitrogen, oxygen, argon, helium, and / or any mixture of these gases. The use of these chemicals is advantageous because they are generally harmless to the user and do not leave behind hazardous reactive chemical residues after use. This is particularly beneficial because known sterilization techniques using chemicals such as ethylene oxide or hydrogen peroxide can leave residues after use, potentially posing a hazard to the patient. This has led, for example, to the ban on the use of ethylene oxide in the European Union and restrictions on its use in the United States.

[0065] Furthermore, gases such as air, nitrogen, oxygen, argon, helium, etc. are generally available in hospital environments at reasonable costs, thus limiting sterilization costs.

[0066] Cleaning equipment 12

[0067] As described above, the cleaning device 12 is configured to receive and clean the object 14 .

[0068] The cleaning device 12 includes a housing 16, a radio wave source 18 (eg, a radio frequency generator, etc.), and a controller 22. Preferably, the cleaning device 12 also includes a pump 24.

[0069] Housing 16 is intended to house at least one object 14. Furthermore, housing 16 is fluidically coupled to a pump 24. Housing 16 is also coupled to a radio wave source 18. Furthermore, controller 22 is configured to control the operation of radio wave source 18 and preferably housing 16 and / or pump 24.

[0070] "Radio waves" refer to electromagnetic waves with frequencies below 300 GHz.

[0071] Housing 16

[0072] The housing 16 includes an inner wall 26 that defines an interior cavity 28 for receiving the object 14. The housing 16 also includes a door (not shown) for accessing the interior cavity 28, e.g., for loading the object 14. The housing 16 also includes an input port 30 and an output port 32 for allowing gas to flow into and out of the interior cavity 28.

[0073] The housing 16 may also include at least one sensor 34 configured to perform a measurement of a predetermined physical property within the interior cavity 28 .

[0074] Advantageously, the inner wall 26 is at least partially made of a material that is compatible with high vacuum processes, and preferably a plasma-resistant material, such as aluminum or stainless steel.

[0075] “Plasma-resistant material” in the context of the present invention refers to a material that is not degraded by plasma, i.e., does not lose mass and / or thickness, and / or is not oxidized to an extent that its physical and / or mechanical properties are affected over the predetermined total usage time of the cleaning device 12.

[0076] Preferably, the dimensions of the inner wall 26 are selected so that it can withstand a pressure in the inner cavity 28 of less than 4000 Pa (preferably, including from 0.5x10 -6 Pa to 400Pa, that is, from low vacuum to high vacuum) without causing irreversible deformation.

[0077] Even more preferably, the housing 16 is arranged such that fluid can only flow into and out of the interior cavity 28 through the input port 30 and / or the output port 32 when the door is closed during a cleaning step (disclosed in more detail later in this specification).

[0078] Each of the input port 30 and the output port 32 may have an open position and a closed position to respectively allow or prevent the flow of gas between the interior cavity 28 of the housing 16 and the external environment.

[0079] Each sensor 34 is configured to output a sensing signal representing a current value of a corresponding physical property within the interior cavity 28. For example, the physical property is the pressure or the temperature within the interior cavity 28.

[0080] Radio wave source 18

[0081] The radio wave source 18 is configured to output electromagnetic waves 36 , more specifically radio waves.

[0082] More specifically, the radio wave source 18 has an active state and an inactive state. In the active state, the radio wave source 18 outputs electromagnetic waves 36. In contrast, in the inactive state, the radio wave source 18 does not output any electromagnetic waves.

[0083] More specifically, radio wave source 18 is coupled to housing 16 such that, in an activated state, electromagnetic waves 36 propagate within housing 16 , and more specifically within interior cavity 28 .

[0084] The frequency of the electromagnetic waves 36 belongs to the radio wave range or the microwave range.

[0085] Advantageously, the radio wave source 18 is configured so that the frequency of the electromagnetic waves 36 is included in one or more of the following frequency bands: LF band (or "low frequency band", ranging from 30 kHz to 300 kHz), MF band (or "medium frequency band", ranging from 300 kHz to 3 MHz), and HF band and VHF band (or "high frequency band", ranging from 3 MHz to 30 MHz and 30 MHz to 300 MHz).

[0086] These frequency ranges offer several advantages over other spectral ranges. In fact, the wavelengths of electromagnetic waves in the UHF band ("ultra-high frequency band," ranging from 300 MHz to 3 GHz) are close to the characteristic wavelengths of the materials placed in the enclosure. Consequently, the energy transfer from the electromagnetic waves to the gas inside the enclosure can lead to rapid heating of the materials placed in the enclosure, potentially affecting their physical properties and integrity.

[0087] Furthermore, the UHF band is commonly used for radio communications / telecommunications, resulting in a very high risk of interference with other equipment and potentially causing electromagnetic compatibility issues, particularly in medical environments.

[0088] For example, the radio wave source 18 is configured so that the frequency of the electromagnetic wave 36 falls within a range compatible with standard ISM (Industrial, Scientific and Medical) equipment, which uses frequency bands coordinated by the ITU (International Telecommunication Union). These preferred frequency ranges are:

[0089] -6.78MHz±15kHz (i.e. 6.765MHz to 6.795MHz);

[0090] -13.56MHz±7kHz (i.e. 13.553MHz to 13.567MHz); and

[0091] -27.12MHz±163kHz (i.e. 26.957MHz to 27.283MHz).

[0092] These frequency ranges help improve electromagnetic compatibility in medical environments.

[0093] Alternatively or additionally, in particular for objects 14 that are insensitive to interference, the radio wave source 18 is configured so that the frequency of the electromagnetic waves 36 is in the microwave range, i.e., 300 MHz to 300 GHz. For example, the radio wave source 18 is configured so that the frequency of the electromagnetic waves 36 is in the range of 1 GHz to 5 GHz, preferably in the range of 2 GHz to 3 GHz, for example, equal to 2.45 GHz.

[0094] 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 that, when a suitable pressure and gas composition are reached in the interior cavity 28, the radio wave source 18 is controlled so as to enter an activated state, thereby igniting a non-thermal plasma in the interior cavity 28. For an example of a technique for generating non-thermal plasma implemented in sterilization, reference can be made to the publication “From patent to product? 50 years of low-pressure plasma sterilization”, Fiedrandt et al., Plasma Process Polymers, 2018.

[0095] Controller 22

[0096] As previously described, the controller 22 is configured to control the operation of the radio wave source 18 .

[0097] More precisely, the controller 22 is configured to perform at least two, preferably at least three, non-thermal plasma generation cycles in succession during a cleaning step for cleaning the object 14. In this case, the controller 22 is configured to control the radio wave source 18 during each non-thermal plasma generation cycle to:

[0098] - being active for a first predetermined duration; and

[0099] - being inactive for a second predetermined duration following the first predetermined duration.

[0100] Each of the first predetermined duration and the second predetermined duration is strictly greater than zero.

[0101] Thus, if the appropriate pressure and gas composition are achieved within the interior cavity 28 , a non-thermal plasma is generated within the enclosure 16 , thereby causing cleaning of the object 14 .

[0102] Furthermore, the input port 30 is in the open state during the second predetermined duration to allow gas to flow from the gas supply device 10 to the housing 16, and more precisely to the internal cavity 28. Possibly, the input port 30 may also be in the open state during the first predetermined duration or during a portion of the first predetermined duration, when the radio wave source is active.

[0103] For example, the controller 22 is configured to control the position of the input port 30 so that the input port 30 is in the open position during the second predetermined duration and possibly at least during part of the first predetermined duration. Alternatively, the input port 30 does not require control by the controller 22 and is always in the open position.

[0104] Thanks to the present invention, more efficient cleaning is achieved compared to known non-thermal plasma cleaning devices. In fact, the inventors have discovered that the reaction kinetics associated with plasma generation are such that the chemical species that contribute most to the degradation of undesirable chemicals and / or pathogens (i.e., excited free radicals and / or molecules) (hereinafter referred to as "reactants of interest") are present in very small quantities in the steady state compared to other less reactive species. In contrast, in transient states, the proportion of the reactants of interest increases significantly.

[0105] Thus, by performing a plurality of such non-thermal plasma generation cycles, and by allowing gas to flow from the gas supply to the housing for at least the predetermined second duration of each non-thermal plasma generation cycle, reactants of interest that are present when the plasma is ignited are regenerated, thereby providing improved cleaning performance to the cleaning apparatus according to the present invention.

[0106] Furthermore, the ignition of the plasma within the internal cavity 28 itself produces results far superior to those achieved by known apparatuses that use afterglow discharge (also known as "plasma beam cleaning") for cleaning.

[0107] In practice, during plasma beam cleaning, a gas stream passes through a discharge region, where plasma is ignited. The plasma is then transported to the object to be cleaned, located at a distance from the discharge region. However, the inventors have discovered that the aforementioned reactants of interest include those with very short lifespans. Consequently, by the time the plasma reaches the object to be cleaned, the reactants of interest have almost completely undergone chemical changes, rendering them ineffective. In contrast, thanks to the present invention, the plasma is ignited around the object to be cleaned, overcoming the problems associated with plasma transport.

[0108] Preferably, the first predetermined duration is less than 5 minutes, preferably less than 3 minutes, advantageously less than 2 minutes, such as less than 1 minute for each non-thermal plasma generation cycle.

[0109] In practice, as mentioned above, the reactants of interest are mixtures comprising reactants with short lifetimes, and increasing the first duration beyond a certain time (typically the lifetime of a fraction of the reactants of interest) does not bring significant advantages.

[0110] Preferably, the controller 22 is configured to perform at least two, in particular at least three, and preferably at least five non-thermal plasma generation cycles in succession during the cleaning step.

[0111] 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, such as less than 30 seconds.

[0112] In fact, the second duration should be as short as possible because during the second duration no cleaning can be achieved due to the absence of plasma. This is because the plasma in the housing 16 disappears quickly (within a few seconds, typically less than 5 seconds) once the radio wave source 18 switches to its inactive state.

[0113] Advantageously, the size of the input port 30 is such that during the second predetermined duration, a predetermined amount of gas is injected into the housing 16, and more specifically, into the internal cavity 28. By way of example, the amount of gas injected is at least equal to the amount of gas present in the internal cavity 28 during the first duration, and preferably at least three times that amount, for example, at least ten times that amount. In other words, the size of the input port 30 is such that during the second predetermined duration, the gas in the internal cavity 28 is refreshed before the next non-thermal plasma generation cycle.

[0114] The flow rate of the pump 24 may also be optimized in conjunction with the input port 30 such that during the second predetermined duration, the gas in the internal cavity 28 is refreshed prior to the next non-thermal plasma generation cycle.

[0115] For example, if the molecular oxygen flow rate is 1 scmm (Standard Cubic Centimeters per Minute) and the pressure in the inner cavity is 10 -4 mbar (millibar), the temperature of the gas at the input port is 273.15K (Kelvin), and the volume of the internal cavity 28 is 10L, the second predetermined duration can be as short as 5 seconds.

[0116] As previously described, the controller 22 is also configured to operate the pump 24. More specifically, the controller 22 is configured to control the pump 24 such that the pressure within the enclosure is below a predetermined threshold during at least one non-thermal plasma generation cycle.

[0117] Preferably, the predetermined threshold is lower than 4000 Pa, preferably 0.5x10 -6 Pa to 400Pa.

[0118] Advantageously, the controller 22 is configured to operate the pump 24 based on sensing signals output by the one or more sensors 34 , and more specifically based on the pressure within the housing 16 (ie, within the interior cavity 28 ) derived from the sensing signals.

[0119] Advantageously, the controller 22 is configured to operate the radio wave source 18 based on the sensing signals output by the one or more sensors 34, and more precisely based on the temperature of the object 14 derived from the sensing signals. For example, the controller 22 is configured to control the radio wave source 18 so that the radio wave source 18 is inactive if the temperature of the object 14 is greater than a predetermined maximum value. Thus, heat-related degradation of the object 14 is prevented.

[0120] operate

[0121] The operation of the cleaning assembly 8 will now be described.

[0122] During the initial step, the cleaning apparatus 12 is connected to the gas supply 10. Furthermore, the controller 22 is configured to, for example, store the first duration and the second duration in the controller. The controller 22 may also be configured to store the type of gas provided by the gas supply, and / or the number of non-thermal plasma generation cycles to be performed during the cleaning step, and / or measurements of key parameters of the cycles for process control, regulation, and safety purposes, including but not limited to housing pressure, gas flow rate, and radio wave power.

[0123] Then, during an initial step, at least one object to be cleaned 14 is arranged in the housing 16 , and more precisely in the inner cavity 28 of the housing 16 .

[0124] The housing is closed, and preferably, the pressure within the housing 16 (ie, within the interior cavity 28 ) is below a predetermined threshold, for example, using an optional pump 24 connected to an output port 32 of the housing 16 .

[0125] Then, during the cleaning step, controller 22 successively performs at least two, preferably at least three, non-thermal plasma generation cycles, for example based on the type of gas provided by gas supply 10 and / or a previously stored number of non-thermal plasma generation cycles to be performed.

[0126] As previously described, during each non-thermal plasma generation cycle, the controller 22 controls the radio wave source so that:

[0127] - being in an activated state for a first predetermined duration, thereby generating a non-thermal plasma in the housing 16; and

[0128] - being inactive for a second predetermined duration following the first predetermined duration.

[0129] Furthermore, during the second predetermined duration, a flow of gas is injected into the housing 16. In other words, during the second predetermined duration, the position of the input port 30 allows gas to flow from the gas supply to the housing 16. Possibly, the flow of gas may also be injected into the housing 16 during part or all of the first predetermined duration.

[0130] Then, in the storing step, each cleaned object 14 is stored in a corresponding package.

[0131] Alternatively, the object to be cleaned 14 is placed in a corresponding package 40, such as Figure 3 shown.

[0132] In this case, the packaging 40 can be considered as a housing and is provided with an input port 42 connectable to the gas supply 10 and an output port 44 connectable to the external environment (eg via the pump 24 ).

[0133] For convenience, a frame 44 coupled to the radio wave source 18 is provided so that when the package 40 is arranged in the frame 44 and the radio wave source 18 is in its activated state, electromagnetic waves propagate in the package 40 allowing ignition of a non-thermal plasma.

[0134] In this case, after the cleaning step, the package containing the cleaned objects 14 is removed from the frame and sealed, without the objects 14 having to be arranged in another sealed bag for storage purposes.

[0135] Example

[0136] The cleaning assembly disclosed hereinbefore has been implemented in comparative experiments in connection with the treatment of spores, in particular spores of Bacillus subtilis.

[0137] For this purpose, a suitable dilution of the Liophilchem spore suspension was smeared on a glass slide to prepare 10 spores on a 2 cm x 8 cm glass sample. 6 In post-processing, the sample was recovered by sonication, vortexing, filtering and then recovering from the filter, and the sample was developed on a gel for UFC numbering.

[0138] Cleaning assembly 8 has been implemented using the following setup:

[0139] - Pressure in housing 16: range 3 x 10 -4 mBar to 1x 10-4 mBar,

[0140] -Frequency and power of electromagnetic waves: 13.56MHz-100W,

[0141] -Magnetic flux density: 0 Gauss to 10 Gauss,

[0142] - Gas inside housing 16: 1 sscm of oxygen.

[0143] Figure 4 Shown is the time evolution of the number of Bacillus subtilis spores (logarithmic scale) exposed to non-thermal plasma in various ways, namely:

[0144] - continuous exposure to non-thermal plasma,

[0145] - discontinuous exposure to non-thermal plasma, wherein the radio wave source is in an "ON" state, i.e. in an active state, for a first predetermined duration of 5 minutes and in an "OFF" state, i.e. in an inactive state, for a second predetermined duration of 5 minutes,

[0146] - discontinuous exposure to a non-thermal plasma, wherein the radio wave source is in an "ON" state for a first predetermined duration of 5 minutes and the radio wave source is in an "OFF" state for a second predetermined duration of 3 minutes,

[0147] - discontinuous exposure to a non-thermal plasma, wherein the radio wave source is in an "ON" state for a first predetermined duration of 3 minutes and the radio wave source is in an "OFF" state for a second predetermined duration of 3 minutes,

[0148] - discontinuous exposure to a non-thermal plasma, wherein the radio wave source is in an "ON" state for a first predetermined duration of 2 minutes and the radio wave source is in an "OFF" state for a second predetermined duration of 2 minutes,

[0149] - discontinuous exposure to non-thermal plasma, wherein the radio wave source is in an "ON" state for a first predetermined duration of 2 minutes and the radio wave source is in an "OFF" state for a second predetermined duration of 1 minute.

[0150] It can be seen that increasing the duration of exposure to the non-thermal plasma (ie, increasing the first predetermined duration) actually increases the number of spores on the object 14 divided by 10. -6 The time required.

[0151] More specifically, if the first duration is at least equal to the lifetime of the reactant of interest, then it is actually the number of cycles that has an impact on the cleaning efficiency. Figure 5This is evident from FIG, which shows the evolution of the number of Bacillus subtilis spores (logarithmic scale) over the non-thermal plasma generation period for the aforementioned durations of exposure to the non-thermal plasma. In other words, the cleaning efficiency depends on the amount of time the object 14 is exposed to the reactant of interest.

[0152] Figure 4 and Figure 5 It has also been shown that sequential control of the generation of non-thermal plasma according to the cycles described above results in a bioburden reduction that is more linear than the bioburden reduction resulting from the continuous generation of non-thermal plasma in known sterilizations.

[0153] In another example, the following settings were used to measure the 10 6 Implementation of cleaning components for Bacillus subtilis spores 8:

[0154] -Pressure in housing 16: ranges from 2x10 -4 mBar up,

[0155] -Frequency and power of electromagnetic waves: 13.56MHz-100W,

[0156] -Magnetic flux density: from 0 Gauss,

[0157] - Gas inside housing 16: 1 sscm of oxygen.

[0158] Table 1 below shows the results of different discontinuous exposures to non-thermal plasma according to cycles, each cycle comprising a first predetermined duration "ON" period of 2 minutes and a second duration "OFF" period of 1 minute with the radio wave source active.

[0159] Logarithm of reduction 1 cycle 1.57 6 cycles 3.53 12 cycles >6

[0160] Table 1

[0161] The following setup was used to measure the 10 6 Bacillus subtilis spores are cleaned using component 8:

[0162] -Pressure in housing 16: ranges from 3x10 -4 mBar up,

[0163] -Frequency and power of electromagnetic waves: 13.56MHz-100W,

[0164] -Magnetic flux density: from 0 Gauss,

[0165] - Gas inside housing 16: 1 sscm of oxygen.

[0166] Table 2 below shows the results of different discontinuous exposures to non-thermal plasma according to cycles, each cycle comprising a first predetermined duration "ON" period of 2 minutes and a second predetermined duration "OFF" period of 1 minute with the radio wave source active.

[0167] Logarithm of reduction 10 cycles 3.21 30 cycles 5.2 40 cycles >6

[0168] Table 2

[0169] The following setup was used to measure the 10 6 Implementation of cleaning components for Bacillus subtilis spores 8:

[0170] -Pressure in housing 16: ranges from 3x10 -4 mBar up,

[0171] -Frequency and power of electromagnetic waves: 13.56MHz-200W,

[0172] -Magnetic flux density: from 0 Gauss,

[0173] - Gas inside housing 16: 1 sscm of oxygen.

[0174] Table 3 below shows the results of different discontinuous exposures to non-thermal plasma according to cycles, each cycle comprising a first predetermined duration "ON" period of 2 minutes and a second predetermined duration "OFF" period of 1 minute with the radio wave source active.

[0175] Logarithm of reduction 37 cycles >6

[0176] Table 3

Claims

1. A non-thermal plasma cleaning apparatus (12), comprising: - a housing (16) for accommodating at least one object to be cleaned, said housing comprising an input port (30) for fluidly connecting said housing to a gas supply; a radio wave source (18) having an active state and an inactive state, wherein in the active state the radio wave source (18) outputs electromagnetic waves (36), and in the inactive state the radio wave source (18) does not output electromagnetic waves (36), wherein the electromagnetic waves (36) have a frequency in the radio wave range or the microwave range, the radio wave source (18) being coupled to the housing (16) such that in the active state the electromagnetic waves (36) propagate in the housing (16); a controller (22) configured to control the radio wave source (56) and the input port (30) to perform at least two, preferably at least three, non-thermal plasma generation cycles in succession during the cleaning step, each non-thermal plasma generation cycle comprising: controlling the radio wave source (18) to be active during a first predetermined duration, thereby generating a non-thermal plasma in the housing (16); and After the first predetermined duration, controlling the radio wave source (18) to be inactive for a second predetermined duration, The input port (30) is open during at least a 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.

2. The non-thermal plasma cleaning apparatus (12) of claim 1 , further comprising a pump (24) fluidly connected to the housing (16), the controller (22) being configured to operate the pump (24) such that the pressure within the housing (16) is below a predetermined threshold during at least one non-thermal plasma generation cycle.

3. The non-thermal plasma cleaning apparatus (12) according to claim 2, wherein: The predetermined threshold is lower than 4000 Pa, preferably 0.5x10 -6 Pa to 400Pa.

4. The non-thermal plasma cleaning device (12) according to any one of claims 1 to 3, wherein: The radio wave source (18) is configured such that the electromagnetic wave (36) has the following frequency: - comprised within the interval range of 30 kHz to 300 MHz, in particular 30 kHz to 300 MHz, preferably within at least one of the following intervals: The range is from 6.765MHz to 6.795Hz; range from 13.553 MHz to 13.567 MHz; and / or The range is from 26.957MHz to 27.283MHz.

5. The non-thermal plasma cleaning apparatus (12) according to any one of claims 1 to 3, wherein: The radio wave source (18) is configured such that the frequency of the electromagnetic wave (36) is between 1 GHz and 5 GHz, preferably between 2 GHz and 3 GHz, for example equal to 2.45 GHz.

6. The non-thermal plasma cleaning apparatus (12) according to any one of claims 1 to 5, wherein: Said first predetermined duration is less than 5 minutes, preferably less than 3 minutes, advantageously less than 2 minutes, for example less than 1 minute.

7. The non-thermal plasma cleaning apparatus (12) according to any one of claims 1 to 6, wherein: Said second predetermined duration is less than 5 minutes, preferably less than 3 minutes, advantageously less than 2 minutes, for example less than 30 seconds.

8. The non-thermal plasma cleaning apparatus (12) according to any one of claims 1 to 7, wherein: The controller (22) is configured to sequentially execute at least five non-thermal plasma generation cycles during the cleaning step.

9. The non-thermal plasma cleaning device (12) according to any one of claims 1 to 8, further comprising at least one sensor (34) configured to output a sensing signal representing the temperature within the housing (16), the controller (22) being further configured to control the radio wave source (18) to be in an inactive state if the temperature determined based on the sensing signal is greater than a predetermined maximum value.

10. A cleaning assembly comprising a gas supply (10) and a non-thermal plasma cleaning apparatus (12) according to any one of claims 1 to 9, the gas supply (10) being fluidly connected to an input port (30) of the housing to provide gas to the housing (16) of the non-thermal plasma cleaning apparatus (12).

11. The cleaning assembly according to claim 10, wherein The gas supply device (10) is configured to supply gas, and the gas includes at least one of air, nitrogen, oxygen, argon and helium.

12. A non-thermal plasma cleaning method comprising the steps of: - arranging at least one object to be cleaned in the housing (16); as well as - performing at least two, preferably at least three, non-thermal plasma generation cycles in succession, each non-thermal plasma generation cycle comprising: controlling the radio wave source (18) to be active during a first predetermined duration to generate a non-thermal plasma in the housing (16); and After the first predetermined duration, controlling the radio wave source (18) to be inactive for a second predetermined duration, injecting a gas flow into the housing at least during the second predetermined duration, wherein, in the activated state, the radio wave source (18) outputs electromagnetic waves (36), and in the inactivated state, the radio wave source (18) does not output electromagnetic waves (36), the electromagnetic waves (36) having a frequency in the radio wave range or the microwave range, the radio wave source (18) being coupled to the housing (16) such that, in the activated state, the electromagnetic waves (36) propagate in the housing (16), Each of the first predetermined duration and the second predetermined duration is strictly greater than zero.

13. The non-thermal plasma cleaning method of claim 12, further comprising: Prior to at least one non-thermal plasma generation cycle, the pressure within the enclosure (16) is brought below a predetermined threshold.

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