Plasma jet device

Abstract

The invention relates to a cold atmospheric-pressure plasma jet device (3) comprising: - at least one capillary tube (20) comprising at least one noble-gas feed inlet (22), a plasma generation zone (24) and at least one plasma outlet (26); the capillary tube comprising, downstream of the plasma generation zone and upstream of a distal part of the capillary tube, a portion (60) having an enlarged cross-section, preferably the portion having the enlarged cross-section having a width-to-height ratio between 0.1 and 1000, the width corresponding to the maximum inner diameter of the portion having the enlarged cross-section.

Description

[0001] Description

[0002] Title: Plasma jet device

[0003] Technical field

[0004] The present invention relates to atmospheric pressure cold plasma jet devices. In particular, the present invention relates to the field of cold plasmas in cosmetic or medical applications, in particular for skin applications such as the treatment of cancer cells, the healing or sterilization of wounds, for example chronic or acute post-operative wounds, or in the context of grafting, post-grafting to promote healing and prevent infections or pre-grafting to prepare the skin.

[0005] Prior art

[0006] The use of cold plasma, produced from a rare gas, typically helium or argon, subjected to an electrical discharge delivered by a high-voltage power supply at room temperature, is well known in the field of medical cutaneous applications. The plasma propagates in a pulsed, and possibly periodic, form until it exits the capillary, and upon contact with the ambient air produces reactive oxygen and nitrogen species, which, together with the electric field, are responsible for the biological effects of cold plasmas.

[0007] Skin treatment with atmospheric pressure cold plasma technique has proven its effectiveness in the treatment of skin injuries, pruritus and skin infections. In particular, plasma is known to accelerate wound healing by promoting re-epithelialization, reducing inflammation through activation of the body's protective mechanisms and recruitment of immune cells to the wound area, activating fibroblasts that induce actin cytoskeleton rearrangement and promote matrix synthesis, activating healing cytokines and growth factors in fibroblasts and keratinocytes, inducing neovascularization and the production of pro-angiogenic proteins in endothelial cells.

[0008] The use of cold plasma has the advantage of being contactless and painless for patients. In addition, treatment times are relatively short, and no allergic reactions, bacterial resistance, or other side effects have been observed to date.

[0009] Furthermore, several studies have shown that bacteria, fungi, biofilms, viruses and spores can be killed very effectively using cold plasma (biocidal activity).

[0010] However, the European-compliant plasma generation devices currently on the market do not allow the power and dose of plasma to be applied to a specific skin area to be controlled. Furthermore, these devices also do not allow the plasma application surface to be modified. In particular, the currently known devices only allow practitioners to control the duration of plasma application, because the power delivered and the distribution of the plasma are non-homogeneous. Performing a treatment based primarily on a duration criterion leads to significant uncertainty and non-reproducibility of the treatment.

[0011] US 8,961,888 describes an atmospheric pressure plasma generator having an increased plasma generation zone in order to treat a large surface area, the plasma generation zone being made of an insulating material, making it possible to stabilize the plasma formation throughout the plasma generation zone. US 8,961,888 specifies that the material of the plasma generation zone may be made of sintered ceramic, a material having mechanical strength qualities making it possible to support the plasma thus generated.

[0012] US 2011 / 0042008 describes a plasma generator for generating a larger volume of plasma and stabilizing the electrical discharge that causes the plasma generation.

[0013] US 2010 / 0147464 describes a plasma treatment apparatus comprising, among other things, an electrode formed from a conductive layer covered with an insulating substrate, the substrate being made of sintered ceramic. The apparatus described in US 2010 / 0147464 makes it possible to obtain a plasma treatment apparatus that is more resistant to electrical discharge instabilities, at a lower cost.

[0014] US 2009 / 0016941 describes a plasma discharge electrode device providing improved energy efficiency.

[0015] Statement of the invention

[0016] There is a continuing need for a device facilitating cold plasma treatment for the treatment of all types of wounds. In particular, there is a need for a device ensuring the reproducibility of skin treatment and allowing the treatment to be adapted to each type of wound, particularly large wounds. There is also a continuing need for a device that can minimize the duration of cold plasma treatment and ensure its safety.

[0017] The invention aims to meet all or part of these needs.

[0018] Summary of the invention

[0019] Plasma diffuser

[0020] According to a first aspect of the invention, the invention relates to an atmospheric pressure cold plasma jet device comprising:

[0021] - at least one capillary tube comprising at least one rare gas supply inlet, a plasma generation zone, and at least one plasma outlet;

[0022] - at least one plasma diffuser arranged on the exit path of the capillary tube positioned so that the plasma generated in the plasma generation zone passes through the plasma diffuser, the plasma diffuser being made of a porous material whose median pore diameter is advantageously between 0.1 pm and 5 mm, better still greater than 1 pm and less than 1 mm, even better still greater than 10 pm and less than 500 pm.

[0023] A device according to the invention allows for homogeneous diffusion of the plasma. It also makes it possible to easily treat large wounds and reduce the application time.

[0024] In particular, the presence of the plasma diffuser on the exit path of the capillary tube makes it possible to treat surfaces ranging from 1 to 50 cm 2, homogeneously, in a single plasma pulse. The presence of the plasma diffuser at the outlet of the capillary tube can in fact make it possible to multiply by a factor of 1000 the surface area on which the generated plasma can be applied, compared to a device not including any diffuser element.

[0025] Finally, the use of a device according to the invention allows for reduced consumption of rare gas. In particular, such a device advantageously makes it possible to limit losses during the ejection of the plasma from the device.

[0026] A capillary tube is a tube in which the cold plasma jet is created and propagates.

[0027] A plasma diffuser promotes the increase of the plasma jet cross-section. The median pore diameter of the plasma diffuser may be greater than 0.1 pm and less than 5 mm, better still greater than 1 pm and less than 1 mm, even better greater than 10 pm and less than 500 pm, even better greater than 40 pm and less than 100 pm, even better greater than 50 pm and less than 80 pm.

[0028] The plasma diffuser can have a thickness between 100 pm and 5 cm, better between 500 pm and 1 cm, even better between 800 pm and 0.5 cm.

[0029] The thickness of the plasma diffuser can be variable.

[0030] Preferably, the thickness of the plasma diffuser is constant.

[0031] The plasma diffuser may be made of a dielectric, semiconductor, metallic or metallic material coated with a dielectric material, or a combination of these materials, preferably the plasma diffuser is made of a dielectric material.

[0032] In one embodiment of the invention, the plasma diffuser is made of sintered ceramic, preferably sintered glass, comprising for example materials with a high dielectric constant such as alumina or perovskites.

[0033] The plasma diffuser can extend in a plane perpendicular to the direction of propagation of the plasma in the capillary tube.

[0034] In one embodiment, a plurality of plasma diffusers are disposed along the exit path of the capillary tube and are positioned such that plasma generated in the plasma generation zone passes through the plasma diffusers in succession.

[0035] The capillary tube may comprise a distal portion, comprising the plasma outlet, which is flared. The flared distal portion may extend over a length, in the direction of propagation of the plasma, less than or equal to 20 cm, preferably less than or equal to 10 cm, more preferably less than or equal to 5 cm. The ratio of the maximum diameter of the distal portion to the minimum diameter of the distal portion may be between 1 and 100.

[0036] The diameters are measured perpendicular to the direction of plasma propagation and are internal, i.e. the walls of the tube are not taken into account for the diameter measurement.

[0037] Preferably, the plasma diffuser is positioned in the flared distal portion of the capillary tube, perpendicular to the direction of propagation of the plasma in the capillary tube.

[0038] The plasma diffuser positioned in this way allows for stabilization of the plasma over a larger dimension. In addition, the plasma diffuser prevents backscattering of air towards the flared distal part, thus improving the stability and homogeneity of the plasma passing through the diffuser.

[0039] The plasma diffuser can be positioned at the end of the flared distal portion, i.e. the plasma diffuser can be positioned at the distal portion of the capillary tube with the largest diameter.

[0040] The capillary tube may have a wall of fixed thickness or of variable thickness. In the particular case of a wall of variable thickness, the wall of the distal portion may be wider than the wall of the plasma generation zone. The wall of the distal portion may have a thickness of between 0.1 mm and 5 mm. The ratio of the thickness of the wall of the plasma generation zone to the thickness of the distal portion may be between 0.1 and 10.

[0041] A device according to the invention may comprise more than two plasma outlets and / or more than two capillary tubes. Preferably, the number of plasma outlets is between 1 and 100, preferably between 1 and 50, better still between 1 and 10.

[0042] In one embodiment of the invention, the device comprises a capillary tube having 3 plasma outlets, each plasma outlet having a plasma diffuser.

[0043] In a preferred embodiment of the invention, the device comprises several capillary tubes, each capillary tube comprising 3 plasma outlets, each of the plasma outlets comprising a plasma diffuser, preferably each capillary tube comprising a rare gas supply inlet.

[0044] A plasma diffuser may be positioned on the exit path of each plasma outlet, the plasma device having as many plasma diffusers as there are plasma outlets. Alternatively, a plasma diffuser may be positioned on the exit path of multiple plasma outlets.

[0045] According to another variant of the invention, several successive plasma diffusers can be positioned on the exit path of each plasma outlet.

[0046] The plasma diffuser can be brought to a predetermined potential. Preferably, the plasma diffuser can be at a floating potential or connected to an active or passive electrode, allowing the plasma propagation to be modulated.

[0047] Buffer volume According to a second aspect of the invention, the invention relates to an atmospheric pressure cold plasma jet device comprising:

[0048] - at least one capillary tube comprising at least one rare gas supply inlet, a plasma generation zone, and at least one plasma outlet; the capillary tube comprising, downstream of the plasma generation zone and upstream of a distal part of the capillary tube, a portion of enlarged cross-section, preferably the portion of enlarged cross-section having a width / height ratio of between 0.1 and 1000, preferably between 0.5 and 100, better still between 0.8 and 10, the width corresponding to the maximum internal diameter of the portion of enlarged cross-section.

[0049] The width corresponds to the maximum internal diameter of the enlarged cross-sectional portion, the diameter being measured perpendicular to the direction of propagation of the plasma in the tube. The diameter is said to be internal, that is to say that the walls of the tube are not taken into account.

[0050] The enlarged cross-sectional portion forms a buffer volume that allows the plasma ignition voltage to be reduced by approximately 20%, i.e. the voltage required to be applied to an electrode to enable plasma formation in the plasma generation zone of the capillary tube. Plasma propagation requires less energy. In addition, the generated electromagnetic noise is reduced.

[0051] The enlarged cross-sectional portion advantageously opens into a bottleneck towards the plasma outlet.

[0052] The enlarged cross-sectional portion may in particular have a maximum diameter greater than the maximum diameter of the plasma generation zone and / or the maximum diameter of the distal part of the capillary tube.

[0053] Furthermore, such an enlarged cross-sectional portion allows for better control of the plasma dose, i.e. the amount of plasma energy, transferred out of the device and thus control of the application of the plasma to the surface to be treated.

[0054] The device may include a sensor measuring the pressure in the enlarged cross-sectional portion and / or the plasma propagation velocity in the capillary tube.

[0055] The enlarged cross-sectional portion may be located at a distance of between 0 cm and 10 cm from the plasma outlet, preferably between 0 cm and 7 cm, more preferably between 0 cm and 5 cm. The diameter of the enlarged cross-sectional portion may be variable, in particular it may increase and then decrease from upstream to downstream.

[0056] The internal volume of the enlarged cross-sectional portion may have a shape adapted to the flow of the gas, substantially spherical, better spherical, substantially ellipsoidal, better ellipsoidal, or substantially cylindrical, better cylindrical, substantially parallelepipedal, better parallelepipedal.

[0057] Of course, this list is not exhaustive. The interior volume of the enlarged cross-sectional portion may have other geometric shapes. In particular, the shape may or may not include an axis or center of symmetry, or may be a combination of the aforementioned shapes.

[0058] The inner volume of the enlarged cross-sectional portion can be between 0.2 cm 3 and 250 cm 3 , preferably between 0.5 cm 3 and 200 cm 3 , better between 1 cm 3 and 25 cm 3 .

[0059] The minimum diameter of the capillary tube can be the diameter of the bottleneck, i.e. the diameter of the outlet of the enlarged cross-sectional portion, in the direction of plasma propagation.

[0060] Preferably, the diameter of the inlet of the enlarged cross-sectional portion is greater than the diameter of the bottleneck.

[0061] The bottleneck can be raised to a predetermined potential. The predetermined potential can be chosen so as to maintain the cold plasma in the enlarged cross-sectional portion, the predetermined potential being modified to allow the cold plasma to move towards the plasma outlet.

[0062] In a particular embodiment, the capillary tube has several plasma outlets, the enlarged cross-sectional portion having several bottlenecks each leading to a plasma outlet.

[0063] Alternatively, the capillary tube has several plasma outlets, for each of the plasma outlets, a portion of enlarged cross-section being provided in the capillary tube.

[0064] The ratio of the maximum diameter of the enlarged cross-sectional portion to the diameter of the feed inlet and / or the maximum diameter of the enlarged cross-sectional portion to the diameter of the bottleneck may be between 1 and 1000, preferably between 1 and 500, more preferably between 1 and 50. The ratio of the maximum diameter of the enlarged cross-sectional portion to the minimum diameter of the capillary tube may be between 2 and 40.

[0065] In a particular embodiment, the distal portion is flared. The capillary tube may have a minimum diameter cross-section between the widened cross-sectional portion and the flared distal portion.

[0066] Alternatively, the diameter of the distal portion of the capillary tube is constant.

[0067] The enlarged cross-sectional portion may have a wall of lesser thickness than a wall of the distal portion.

[0068] The ratio of the wall thickness of the distal portion to the wall thickness of the enlarged cross-sectional portion can be between 1 and 4.

[0069] The enlarged cross-sectional portion may be of a material distinct from the capillary tube. Preferably, the enlarged cross-sectional portion is integral with the capillary tube.

[0070] The capillary tube having at least one rare gas supply inlet, at least one plasma outlet, a plasma generation zone and a portion of enlarged cross-section can be manufactured by molding or blowing, or by additive manufacturing.

[0071] The capillary tube having at least one rare gas supply inlet, at least one plasma outlet, a plasma generation zone and a portion of enlarged cross-section may be made of glass or any insulating material with a high dielectric constant.

[0072] The capillary tube having at least one rare gas supply inlet, at least one plasma outlet, a plasma generation zone and a portion of enlarged cross-section may be monolithic.

[0073] The maximum diameter of the capillary tube is preferably less than 3 mm, more preferably less than 1 mm.

[0074] The capillary tube may be partially removable. In particular, the distal portion may be removable. Preferably, the portion downstream of the plasma generation zone is removable, i.e., it can be disengaged, unscrewed from the portion comprising the plasma generation zone and the rare gas supply inlet.

[0075] The removable downstream portion and the upstream portion comprising the plasma generation zone and the rare gas supply inlet may comprise a form fit. In particular, the upstream portion may comprise a form fit with several different removable downstream portions.

[0076] Priming

[0077] A device according to the invention may comprise a high-voltage electrode fixed to the outer wall and / or to the inner wall of the capillary tube, the device being configured so that the electrode delivers a first electrical signal and a second electrical signal having two distinct frequencies, the frequency of the first electrical signal being defined so that when the electrode delivers this first electrical signal, the rare gas introduced into the capillary tube and subjected to the voltage of the first electrical signal generates the plasma, the frequency of the second electrical signal being defined so as to generate a pulse for initiating propagation of the plasma towards the plasma outlet, the frequency of the second electrical signal being lower than the frequency of the first electrical signal, preferably in a first signal frequency / second signal frequency ratio greater than 1 and less than or equal to 1000, preferably between 3 and 100,better understood between 5 and 50.,

[0078] The second signal advantageously allows the initiation and / or acceleration of the propagation of the plasma in the capillary tube.

[0079] The second signal allows in particular to adapt the dose of plasma ejected from the device.

[0080] Plasma dose is the amount of plasma energy delivered to the target.

[0081] In one embodiment of the invention, the first electrical signal is a carrier wave modulated by the second signal. Such an embodiment advantageously makes it possible to significantly reduce the electromagnetic noise of a plasma jet device.

[0082] In another embodiment, the first and second electrical signals are delivered via a first electrode and a second electrode respectively, the first electrode being positioned upstream of the second electrode, in the direction of propagation of the plasma.

[0083] The second electrode can be positioned downstream of the portion of cross-section enlarged in the direction of plasma propagation. The second electrode can be positioned in the distal portion of the capillary tube.

[0084] In a particular embodiment, the device may comprise at least two second electrodes, for example positioned at the bottleneck of a device according to the invention comprising a portion of enlarged cross-section and in the distal part of the capillary tube.

[0085] The first and / or second electrode(s) may be positioned outside or inside the wall of the device.

[0086] The device may comprise a switch, the second electrical signal being emitted when the switch is in the closed position. Thus, the second electrical signal may be delivered only when a switch is open, for example when a push button is pressed.

[0087] The first signal can be a continuous, alternating or pulsed or mixed signal.

[0088] The second signal can be a continuous, alternating or pulsed signal.

[0089] Advantageously, a device according to the invention makes it possible to better control the plasma dose at the outlet of the device.

[0090] Parameter control

[0091] A device according to the invention may comprise one or more sensors, for example chosen from: a voltage sensor, a power sensor, a frequency sensor, a flow sensor, a distance sensor or a thermal sensor.

[0092] A sensor can be configured to measure the power of the plasma delivered at the output of the plasma diffuser and / or at the output of the plasma generator.

[0093] A sensor may be configured to measure a voltage between the plasma delivered at the output of the plasma diffuser and a surface to which the plasma is intended to be applied or between the plasma delivered at the output of the plasma generator and a surface to which the plasma is intended to be applied.

[0094] A sensor can be configured to measure the temperature when applying the cold plasma to the surface to which the plasma is intended to be applied.

[0095] Preferably, the device according to the invention further comprises a control module configured to analyze the measurements from one or more sensors. The control module can be configured to modify, as a function of analyzed measurements from one or more sensors, a voltage or a frequency of an electrical signal delivered for the generation of the plasma in the plasma generation zone, a voltage or a frequency of an electrical signal delivered to trigger or accelerate the propagation of the plasma in the capillary tube, a dose of plasma ejected by the device onto the target, the target corresponding to the surface on which the plasma is intended to be applied, a temperature of the plasma at the plasma outlet of the capillary tube, a pressure in the plasma generation zone, a pressure of the rare gas in the capillary tube, a pressure in a portion of enlarged cross-section, a flow rate of the rare gas at the supply inlet.

[0096] In one embodiment, the control module presents the measurements and / or analyses of the measurements on a digital interface. An operator can then easily modify a frequency, a voltage, a pressure and / or a flow rate to adapt the desired plasma dose at the output of the device and / or select a particular plasma regime mode.

[0097] Cold plasmas exist in a wide variety of regimes and their discharges have different typologies depending on the production conditions (diffusive jet discharges, filamentary discharges, hollow cathode discharge).

[0098] Plasma regime mode is understood to mean a mode of operation of the plasma allowing a particular type of discharge to be achieved.

[0099] A device according to the invention advantageously allows an adaptation of the dose of plasma delivered in real time, facilitating application and guaranteeing the safety of a treatment.

[0100] Preferably, a device according to the invention comprises several capillary tubes, a control module and sensors, and possibly a digital interface, the device preferably being configured so that the capillary tubes are controlled independently of each other.

[0101] Method of use

[0102] The invention also relates, according to another of its aspects, to the use of a porous material, comprising pores with a median diameter of between 0.1 pm and 5 mm as a plasma diffuser, preferably in a cold plasma jet device. The porous material may comprise pores with a median diameter of between 1 pm and 1 mm, better still between 10 pm and 500 pm, even better still between 40 pm and 100 pm, even better still between 50 pm and 80 pm.

[0103] The porous material can have a thickness between 100 pm and 5 cm.

[0104] The porous material may be of variable thickness. Preferably, the porous material has a constant thickness.

[0105] The porous material may be made of a dielectric, semiconducting, metallic or metallic material coated with a dielectric material, preferably the porous material is made of a dielectric material.

[0106] Preferably, the porous material is sintered ceramic, preferably sintered glass, comprising for example materials with a high dielectric constant such as alumina or perovskites.

[0107] The use of a porous material according to the invention as a plasma diffuser can be exploited in any field of application using cold plasmas and in particular for surface treatment or grafting or bonding or propulsion applications.

[0108] Preferably, the invention relates to the use of a porous material according to the invention as a plasma diffuser in medical application devices.

[0109] The various aspects of the invention may be combined with each other. In particular, a device according to the invention may comprise a plasma diffuser and a portion of enlarged cross-section.

[0110] The terms "upstream", "downstream", "input", "output" are defined relative to the direction of propagation of the rare gas and the plasma. The terms "interior", "exterior" are defined relative to the positioning of the plasma relative to the device, the plasma being inside the device.

[0111] Brief description of the drawings

[0112] The invention may be better understood by reading the detailed description which follows, non-limiting examples of its implementation, and by examining the attached drawing, in which:

[0113] [Fig 1] Figure 1 shows a schematic view of a longitudinal section of a plasma generation device illustrating the generation of a cold plasma, [Fig 2] Figure 2 shows a schematic view of a longitudinal section of a plasma jet device comprising a plasma diffuser according to the invention,

[0114] [Fig 3] Figure 3 represents a view of a longitudinal section of a plasma jet device comprising a plasma diffuser according to the invention,

[0115] [Fig 4a], [Fig 4b], [Fig 4c], [Fig 4d] and [Fig 4e] Figures 4a, 4b, 4c, 4d and 4e illustrate different embodiments of a device comprising a plasma diffuser according to the invention,

[0116] [Fig 5] Figure 5 shows schematically the application of a plasma to a surface using a plasma jet device,

[0117] [Fig 6] Figure 6 is a graph illustrating the propagation and diffusion of a plasma by means of a device according to Figure 5;

[0118] [Fig 7] Figure 7 shows a plasma jet device comprising, among other things, a portion of enlarged cross-section,

[0119] [Fig 8] Figure 8 shows a plasma jet device comprising a portion of enlarged cross-section according to the invention,

[0120] [Fig 9] Figure 9 is a diagram showing a view from below, in transparency, of a device comprising a portion of enlarged cross-section according to the invention, and

[0121] [Fig 10] Figure 10 is an example of a device according to the invention comprising a portion of enlarged cross-section and a plasma diffuser.

[0122] In the remainder of the description, elements that are identical or have identical functions bear the same reference sign. Their description is not repeated with respect to each of the figures, only the main differences between the embodiments being mentioned.

[0123] Detailed description

[0124] Figure 1 illustrates the operation of a plasma jet device 1 of the prior art.

[0125] Conventionally, the cold plasma is created in a dielectric tube 10 comprising a rare gas 12 at room temperature, an electrode 14 fixed on the dielectric tube 10 creates an electromagnetic field. The rare gas 12, subjected to this electromagnetic field, is at the origin of the generation of the cold plasma 16. A jet of cold plasma 16 is ejected from the device 1.

[0126] Figure 2 shows a schematic view of a longitudinal section of a plasma jet device 2 according to the invention comprising a plasma diffuser 28.

[0127] The device 2 comprises, among other things, a capillary tube 20 comprising at least one supply inlet 22 for rare gas 12, a plasma generation zone 24, and at least one plasma outlet 26, and a plasma diffuser 28 arranged on the outlet path of the capillary tube positioned so that the plasma 16 generated in the plasma generation zone 24 passes through the plasma diffuser 28, the plasma diffuser being made of a porous material whose median pore diameter is between 0.1 pm and 5 mm, preferably between 1 pm and 1 mm, better still between 10 pm and 0.5 mm.

[0128] At the tube outlet, the plasma 16 spreads homogeneously over a large application surface.

[0129] The noble gas 12 may be helium, argon, neon, or a mixture of gases, for example, argon with 5% oxygen. Preferably, the noble gas is helium.

[0130] The flow rate of rare gas can be between 0.2 L / min and 5 L / min, preferably around 1 L / min.

[0131] At least one high voltage electrode 14 is fixed on the outer wall of the capillary tube, allowing the generation of plasma in the plasma generation zone 24 from the rare gas 12 introduced through the supply inlet 22.

[0132] The electrode can deliver a sinusoidal electrical signal with a frequency of between 50 Hz and 100 kHz, preferably about 10 kHz, and a voltage of between 1 kV and 30 kV, preferably between 2 kV and 4 kV.

[0133] A second electrode 30 can be fixed to the wall of the capillary tube 20, downstream of the first electrode 14, in the direction of propagation of the plasma.

[0134] The second electrode may be a low voltage or high voltage electrode. Preferably, the second electrode is a low voltage electrode, thereby limiting the electromagnetic noise induced by the device 2.

[0135] The second electrode advantageously makes it possible to initiate or accelerate the propagation of the cold plasma 16 by capillarity in the capillary tube 20.

[0136] The second electrode may be controlled by a control module (not shown). In particular, the control module may be configured to allow a user to adapt the plasma dose output from the device, by controlling the voltage delivered by the electrode(s). For example, the control module may be configured so that when a switch is closed, a voltage is delivered via the second electrode, and when the switch is open, no voltage is delivered via the second electrode.

[0137] In a particular embodiment of the invention, a single electrode 14 delivers a first electrical signal and a second electrical signal, for example via a modulated signal, comprising a carrier frequency / and a lower frequency signal, the frequency of the lower frequency signal.

[0138] The high frequency carrier allowing the generation of cold plasma, and the lower frequency signal allowing the propagation and / or acceleration of the propagation of the cold plasma to be triggered.

[0139] The electrode(s) 14; 30 are preferably positioned against the outer surface of the wall of the capillary tube. The plasma thus produced is isolated from the electrode(s) by the thickness of the wall of the capillary tube and can be brought into contact with a living organism without danger of electric shock or heating.

[0140] The porous material 28 may comprise pores whose median diameter is between 1 μm and 5 mm.

[0141] The thickness of the porous material e28 can be between 100 pm and 5 cm.

[0142] The thickness of the porous material e28 can be variable. Preferably, the thickness of the porous material C28 is constant.

[0143] Figure 3 illustrates another embodiment of a device 2 according to the invention. The device differs from the example shown in Figure 2 in particular in that it comprises a flared distal part 20a, the plasma diffuser 28 being positioned in this flared distal part 20a. The combination of a flared distal part and a plasma diffuser made of a porous material according to the invention makes it possible to considerably increase the application surface of the cold plasma at the outlet of the device.

[0144] The plasma diffuser 28 may be disposed at the distal end of the capillary tube, as shown for example in Figures 4a, 4c and 4d.

[0145] Alternatively, the plasma diffuser 28 may be arranged in the distal portion of the capillary tube, inside the capillary tube, and not necessarily at the periphery, as shown in FIG. 4b. In particular, a distance d28,26 less than or equal to 10 mm may separate the plasma outlet 26 from the porous material 28.

[0146] A device according to the invention may comprise several rare gas supply inlets 22, possibly several plasma generation zones 24, and a plasma outlet 28. Such an example is shown in Figure 4c.

[0147] A device according to the invention may comprise several plasma outlets 26, a plasma diffuser 28 may be arranged on the path of each of the outlets 26 of the capillary tube, as illustrated in figure 4d.

[0148] The number of plasma outlets 26 is not limited to 1 or 2. A device according to the invention may comprise more than two plasma outlets, in particular a capillary tube 20 may comprise 3 plasma outlets. Preferably, the number of plasma outlets is between 1 and 100.

[0149] A device according to the invention can receive the plasma outlets, or plasma heads, in a modular, removable and interchangeable form. In particular, the plasma outlets can be mechanically fixed to the capillary tube.

[0150] A device according to the invention may comprise several capillary tubes 20, as illustrated in Figure 4e.

[0151] A device according to the invention comprising several capillary tubes 20 may comprise capillary tubes which differ from one another. The capillary tubes 20 may differ from one another by their number of supply inlet(s) 22, their number of plasma outlet(s) 26, the presence of one or more plasma diffuser(s) 28, the presence of a portion of enlarged cross-section 60, their maximum or minimum diameter of the capillary tube, the thickness of the wall of the capillary tube, or the presence of a flared distal portion 20a. This list is not limiting.

[0152] Figure 6 is a graph illustrating the propagation of a plasma in a capillary tube 20 having a porous material 28' on the plasma exit path.

[0153] The results shown in this graph were obtained by experimentation, using a device such as shown in Figure 5, in which the porous material 28' comprises pores whose median diameter is between 40 pm and 100 pm.

[0154] In the experiment, the plasma was generated in a capillary tube 20 subjected to an electromagnetic field by means of a high-voltage annular copper electrode 14, the plasma being applied to a glass target surface 4 under which an aluminum strip was deposited, a gap of 5 mm separating the plasma outlet 26 of the capillary tube from the target surface 4, the electrode 14 generating an electrical signal with a voltage of approximately 4.4 + / -0.30 kV, at a frequency of 15 kHz.

[0155] Graph 6 has a number of pixels as its abscissa and ordinate axes, one pixel being equal to 50 pm.

[0156] In this graph, we observe in particular a first phase 51 where the plasma propagates along the capillary tube 20, a second phase 52 where the plasma reaches and passes through the porous material 28', and finally a third phase 53 where the plasma passes through the porous material 28' and is applied to the surface 4.

[0157] A homogeneous diffusion of the plasma is observed, with the plasma extending over a relatively larger surface area.

[0158] Figure 7 shows a plasma jet device 3 according to the invention comprising a portion of enlarged cross-section 60.

[0159] The device 3 shown in Figure 7 comprises a capillary tube 20 having a rare gas supply inlet 22, a plasma generation zone, the plasma being generated by the electrode 14, and a plasma outlet 26; the capillary tube comprising, downstream of the plasma generation zone and upstream of a distal part of the capillary tube 20a, a portion of enlarged cross-section 60.

[0160] In one embodiment, the enlarged cross-sectional portion 60 may include the plasma generation zone 24.

[0161] The enlarged cross-sectional portion 60 may have a maximum diameter to height ratio, D p , ma x / h p , between 0.1 and 100.

[0162] The enlarged cross-sectional portion advantageously opens onto a bottleneck 62 in the direction of the plasma outlet 26.

[0163] The enlarged cross-sectional portion 60 may be located at a distance D from the plasma outlet, between 0 and 10 cm.

[0164] The diameter of p of the enlarged cross-sectional portion may be variable, in particular it may increase and then decrease from upstream to downstream. In one embodiment, the diameter d p of the enlarged cross-sectional portion may decrease from upstream to downstream. The interior volume of the enlarged cross-sectional portion may have a substantially spherical, better spherical, substantially ellipsoidal, better ellipsoidal, or substantially cylindrical, better cylindrical, shape. These examples are not limiting.

[0165] The inner volume of the enlarged cross-sectional portion can be between 0.2 cm 3 and 250 cm 3 .

[0166] The minimum diameter of the capillary tube can be the diameter of the bottleneck ds .

[0167] In a particular embodiment, the capillary tube has several plasma outlets, the enlarged cross-sectional portion having several bottlenecks 62 each leading to a plasma outlet. An example of such an embodiment is shown in Figure 9. Figure 9 shows a bottom view of a capillary tube 20 having three plasma outlets 26 and an enlarged cross-sectional portion 60.

[0168] Alternatively, for each of the plasma outlets, a portion of enlarged cross-section is provided in the capillary tube.

[0169] The ratio of the maximum diameter of the enlarged cross-sectional portion to the inlet diameter of the enlarged cross-sectional portion d e can be between 1 and 1000, preferably between 1 and 500, better between 1 and 50.

[0170] The ratio of the maximum diameter of the enlarged cross-sectional portion to the diameter of the bottleneck d s can be between 1 and 1000, preferably between 1 and 100, better between 1 and 50.

[0171] Preferably, the diameter of the inlet of the enlarged cross-sectional portion d e is greater than the diameter of the bottleneck d s .

[0172] This advantageously increases the speed of propagation of the plasma in the distal portion of the capillary tube, by venturi effect.

[0173] The diameter of the distal portion 20a of the capillary tube may be constant, as shown in Figure 7.

[0174] In a particular embodiment, the distal portion 20a is flared.

[0175] The enlarged cross-sectional portion may have a wall of thickness e p weaker than a wall of the distal part e s, as in the example of Figure 8. The ratio of the wall thickness of the distal part e s on the wall thickness of the enlarged cross-sectional portion e p , e s / e p , can be between 1 and 4.

[0176] The maximum diameter of the capillary tube is less than 3 mm, preferably less than 1 mm.

[0177] A device according to the invention may comprise sensors 64i, 642, in particular optical sensors 64i, thermal sensors, or voltage sensors 642.

[0178] The sensors 64i, 642 can provide measurements to a control module 66 which can retroactively adapt the plasma dose transmitted out of the device, preferably by adapting the treatment time, the power, via the voltage and / or the frequency delivered by a high voltage power supply 70 to the electrode 14 at the origin of the generation of the plasma, the power, via the voltage and / or the frequency delivered by the high voltage power supply to another electrode fixed on the wall of the capillary tube, preferably on the outer wall, preferably downstream of the electrode at the origin of the generation of plasma, for example configured to trigger or accelerate the propagation of the plasma towards the plasma outlet, and / or the flow rate of rare gas at the inlet of the rare gas supply 22.

[0179] The sensors may include voltage sensors measuring a difference in voltages along the capillary tube.

[0180] The sensors may include voltage sensors 642 measuring a voltage difference between the capillary tube and the surface to which the plasma is to be applied 4.

[0181] The sensors may include temperature sensors measuring a temperature at the plasma outlet or a temperature on a surface 4 to which the plasma is intended to be applied.

[0182] The sensors may include flow sensors measuring the flow rate of noble gas entering the supply inlet.

[0183] Sensors may include biosensors, that is, sensors that can detect and transform a biochemical signal into a quantifiable physical signal.

[0184] The sensors include, for example, electrocardiograms, fixed on the surface 4 on which the plasma is intended to be applied.

[0185] The control module 66 can modify one or more parameters chosen from the treatment time, a power, a voltage and / or a frequency delivered by a high voltage power supply 70 to an electrode fixed on the wall of the capillary tube, preferably on the outer wall, and / or a flow rate of rare gas at the inlet of the rare gas supply 22, making it possible to adapt the dose of plasma ejected from the device.

[0186] In a particular embodiment of the invention, the control module 66 does not retroactively adapt the dose of plasma ejected from the device but transmits the measurements provided by the sensors or an analysis of the measurements provided by the sensors to a control interface 68, via digital communication means 72.

[0187] The control interface 72 allows a user to manually control the dose of plasma ejected from the device, and to adapt it based on the measurements provided by the sensors 64i, 642.

[0188] In particular, the user can modify the power, voltage and / or frequency delivered by the high voltage power supply 70 to the electrode 14 at the origin of the generation of the plasma, the power, voltage and / or frequency delivered by a current source to another electrode fixed on the wall of the capillary tube, preferably on the outer wall, preferably downstream of the electrode at the origin of the generation of plasma, for example configured to trigger or accelerate the propagation of the plasma towards the plasma outlet, and / or the flow rate of rare gas at the inlet of the rare gas supply 22, and / or the distance from the plasma outlet 26 to the surface 4 on which the plasma is intended to be applied.

[0189] Figure 10 is an example of implementation of a device according to the invention comprising a plasma diffuser 28 and a portion of enlarged cross-section 60.

[0190] Example

[0191] A comparison of four plasma jet devices was carried out.

[0192] The comparison made it possible to measure a maximum surface area over which a plasma can spread homogeneously, via a plasma jet, when the plasma is generated and applied by means of one of the following four devices: KinPen® MED (Neoplas tools GmbH, Greifswald, Germany), PlasmaDerm® (CINOGY GmbH, Duderstadt, Germany), SteriPlas (Adtec Plasma Technology, Adtec Europe, Hunslow, UK) and a device according to the invention comprising a plasma diffuser.

[0193] The KinPen® MED is a portable device with a continuously generated medical plasma source and comprising a pen-shaped applicator delivering a cold plasma jet at atmospheric pressure using argon as the carrier gas. The typical length of the plasma effluent is 8 to 12 mm with a diameter of 1 mm. The plasma jet is guided vertically in precise and arbitrary 3D movements of approximately 5 mm / s over the target, resulting in an average treatment time of 30 to 60 s / cm2. The KinPen® MED therefore delivers a non-diffuse jet concentrated at a point. The effective treatment area is reduced to a few mm 2 .

[0194] The PlasmaDerm® is a plasma device for large-area treatment. It features multiple configurable plasma heads to cover an area of ​​up to 27 cm 2The plasma source is based on the concept of dielectric barrier discharge (DBD). The carrier gas can be argon or air. However, in a device based on the DBD concept, the generated plasma behaves differently between two alternations of plasma discharge and the inhomogeneity of the transferred plasma requires great expertise from the user. In addition, the device is in direct, mechanical contact with the target.

[0195] The SteriPlas is a large medical device on wheels with an articulated arm with a treatment head that delivers cold argon-based plasma to the treatment area. The plasma torch has 6 electrodes and argon is used as the carrier gas to carry the gas stream to the target. The plasma torch opening has a diameter of 3.5 cm, allowing a treatment area of ​​up to 12 cm. 2 .

[0196] A device according to the first aspect of the invention makes it possible to cover an area of ​​1 to 50 cm 2 with the initial propagation of a single plasma jet, in particular without the need for contact with the target.

[0197] As is now clear, a device according to the invention allows for better plasma propagation. Not only is it possible to treat large areas more quickly and more evenly, but the device also allows for better adaptability and greater dosage accuracy. Such a device is particularly advantageous for the treatment of burns, for example for treating major burn victims. In general, such a device is suitable for treating all types of wounds, in particular chronic wounds of different types. It was not obvious that sintered glass in particular, as a porous material, could be used as a plasma diffuser in cold plasma jet devices.Indeed, even if the use of sintered glass in plasma jet devices is well known in the prior art, due to its mechanical properties such as its resistance to corrosion, wear, compression, high temperatures or chemicals allowing it to withstand the conditions of plasma generation, it has never been envisaged to be able to use it as a diffuser activated by a plasma jet.

[0198] The invention allows dynamic control of the plasma dose ejected from the plasma jet device and thus allows the user to better adapt each treatment according to the wound or clinical context.

[0199] Of course, the invention is not limited to the exemplary embodiments which have just been described.

[0200] In particular, a device according to the invention may comprise a safety system configured to control the dose of plasma ejected from the device, and / or control the current delivered, and / or control a temperature of the plasma at the outlet of the device and / or control a power of the plasma and / or control a rare gas pressure in a rare gas cylinder supplying the rare gas supply inlet of the capillary tube and / or control a rare gas pressure in the capillary tube, in particular in the portion of enlarged cross-section, when the capillary tube comprises one. For example, the safety system may be a fast circuit breaker, or a control of the microcontroller of the high voltage supply of the electrode at the origin of the generation of the plasma.

[0201] A device according to the invention preferably includes redundancy, in particular in order to comply with regulations relating to medical devices.

[0202] In particular, a device according to the invention is preferably configured to comply with all or part of the following standards: ISO 13485:2016, ISO 14971:2019, IEC 62304 / AE2018, IEC 62366-1:2015, ISO 15223-1:2016, ISO 10993, IEC 60601-1, AAMI TIR 57, 14155:2020 (if RIPH1), DIN SPEC 91315. This list is not exhaustive.

[0203] The expression "comprising a" should be understood as a synonym for "comprising at least one".

Claims

Claims 1. Atmospheric pressure cold plasma jet device (3) comprising: - at least one capillary tube (20) comprising at least one rare gas supply inlet (22), a plasma generation zone (24), and at least one plasma outlet (26); the capillary tube comprising, downstream of the plasma generation zone and upstream of a distal part of the capillary tube, a portion of enlarged cross-section (60).

2. Device according to the preceding claim, the portion of enlarged cross-section being located at a distance of between 0 cm and 10 cm from the plasma outlet, preferably between 0 cm and 7 cm, better still between 0 cm and 5 cm.

3. Device according to one of the preceding claims, the diameter of the portion of enlarged cross-section being variable, in particular it increases then decreases from upstream to downstream.

4. Device according to any one of the preceding claims, in which the interior volume of the enlarged cross-sectional portion has a substantially spherical, better spherical, substantially ellipsoidal, better ellipsoidal, or substantially cylindrical, better cylindrical, substantially parallelepipedal, better parallelepipedal shape.

5. Device according to the immediately preceding claim, the internal volume of the portion of enlarged cross-section being between 0.2 cm 3 and 250 cm 3 , preferably between 0.5 cm 3 and 200 cm 3 , better between 1 cm 3 and 25 cm 3 .

6. Device according to any one of the preceding claims, the minimum diameter of the capillary tube being the diameter of a bottleneck into which the portion of enlarged cross-section opens.

7. Device according to any one of the preceding claims, the diameter of the inlet of the portion of enlarged cross-section being greater than the diameter of a bottleneck into which the portion of enlarged cross-section opens.

8. Device according to any one of the preceding claims, a bottleneck into which the portion of enlarged cross-section opens being brought to a predetermined potential.

9. Device according to any one of the preceding claims, the capillary tube comprising several plasma outlets, the portion of enlarged cross-section opening towards several bottlenecks each leading towards a plasma outlet.

10. Device according to any one of claims 1 to 8, the capillary tube comprising several plasma outlets, for each of the plasma outlets, a portion of enlarged cross-section being provided in the capillary tube.

11. Device according to any one of the preceding claims, the enlarged cross-sectional portion having a width / height ratio of between 0.1 and 1000, the width corresponding to the maximum internal diameter of the enlarged cross-sectional portion.

Images