Plasma jet device

Abstract

Plasma Jet Device The invention relates to a cold plasma jet device (1) comprising: - at least one gas supply inlet (2); - at least one tube (4) fluidically connected to the gas supply inlet and comprising at least one plasma outlet (5), the gas supply inlet and the plasma outlet defining a direction of gas and plasma flow; - at least one high-voltage electrode (6) outside the tube configured to generate an electric field in the tube; and - at least one electrically conductive element (7) having a floating electrical potential and extending axially inside the tube at least partially between the high-voltage electrode and the plasma outlet. Figure for the abstract: Fig. 3

Description

Title of the invention: Plasma jet device technical field

[0001] The present invention relates to the field of plasmas, in particular their use in cosmetic or medical applications such as the treatment of cancer cells, the healing or sterilization of wounds, for example of chronic or acute post-operative wounds, or in the context of transplantation, post-transplant to promote healing and prevent infections or pre-transplant to prepare the skin.

[0002] The invention relates more particularly to a cold plasma jet device, in particular at atmospheric pressure.

[0003] The invention also relates to a cold plasma jet generation assembly comprising such a device. Previous technique

[0004] The use of cold plasma, particularly plasma produced from a noble gas, typically helium or argon, subjected to an electrical discharge delivered by a high-voltage power supply at ambient temperature, is well known in the field of cutaneous medical applications. The plasma propagates in a pulsed, and possibly periodic, manner until it exits a tube, and upon contact with ambient air produces reactive oxygen and nitrogen species, which, along with the electric field, are responsible for the biological effects of cold plasmas.

[0005] Skin treatment with atmospheric pressure cold plasma therapy has proven effective in treating skin wounds, pruritus, and skin infections. In particular, plasma is known to accelerate wound healing by promoting re-epithelialization, recruiting and activating immune cells in the wound area, activating fibroblasts which induce actin cytoskeleton rearrangement and promote matrix synthesis, activating healing cytokines and growth factors in fibroblasts and keratinocytes, and inducing neovascularization and the production of pro-angiogenic proteins in endothelial cells.

[0006] The use of cold plasma has the advantage of being, in certain cases, non-contact and painless for patients. Furthermore, treatment times are relatively short, and no allergic reactions, bacterial resistance, or other side effects have been observed to date.

[0007] In addition, several studies have shown that microorganisms such as bacteria, fungi, biofilms, viruses and spores can be killed very effectively by means of cold plasma (biocidal activity).

[0008] Applications FR2300132 and FR2300133, filed on January 5, 2023, disclose a plasma jet generation device. Although entirely satisfactory, the disclosed device operates preferentially with helium as the plasma-generating gas. However, the supply of helium can be relatively difficult.

[0009] There is therefore a need to propose a plasma generation device that facilitates the use of different plasma-generating gases.

[0010] The aim of the invention is to meet at least part of this need. Summary of the invention

[0011] To this end, the invention relates, in one of its aspects, to a cold plasma jet device comprising:

[0012] - at least one gas supply inlet;

[0013] - at least one tube fluidically connected to the gas supply inlet and comprising at least one plasma outlet, the gas supply inlet and the plasma outlet defining a direction of gas and plasma flow;

[0014] - at least one high-voltage electrode outside the tube configured to generate an electric field in the tube; and

[0015] - at least one electrically conductive element having a floating electrical potential and extending axially inside the tube at least partially between the high-voltage electrode and the plasma outlet.

[0016] The conductive element significantly reduces the plasma ignition and maintenance voltage. The invention also limits the peak current and controls the power of the plasma jets, thereby reducing sensations of tingling or even electric shock when the jets are applied to a patient. The position and shape of the conductive element are advantageously chosen to optimize its effect.

[0017] The invention thus makes it easier to use different source gases. The source gas can, in particular, be a noble gas, notably chosen from helium, neon, argon, krypton, or xenon. The source gas can also be a mixture of gases, notably a mixture of a noble gas, particularly argon, and oxygen, for example, a mixture of 95% by mass of argon with 5% by mass of oxygen.

[0018] In particular, the device is especially suited to the use of argon as the source gas, since argon jets are often more difficult to control than helium jets due to the physical properties of argon. The generation of jets of Plasma from argon, for example, requires higher starting voltages than for helium.

[0019] Argon is particularly advantageous for the production of medical plasma because this gas produces plasma at relatively low temperatures compared to some other gases. Furthermore, argon has a relatively low ionization energy, which makes it possible to generate plasma at low power levels. This helps to minimize thermal stress on the treated tissues.

[0020] Floating electrical potential refers to the state of not being in direct electrical contact with an element at a fixed potential. Thus, the conducting element is not electrically connected to any element at a fixed potential.

[0021] The term "tube" refers to a tube in which the cold plasma jet is created and propagates. It may, in particular, be a capillary tube.

[0022] Preferably, the gas supplying the device is at atmospheric pressure, the generated plasma also being at atmospheric pressure.

[0023] According to an optional feature, the high-voltage electrode surrounds the tube, in particular over a proximal portion of the tube. If the device comprises a plurality of tubes, the high-voltage electrode may surround one or more tubes, in particular all of the tubes.

[0024] According to another optional feature, the conducting element and the high-voltage electrode partially overlap axially.

[0025] According to an advantageous feature, the device comprises a ground electrode connected to electrical ground and disposed around the outer wall of the tube, at a distance from the outlet less than that separating the high-voltage electrode from the outlet, downstream of said conductive element, preferably near the plasma outlet, for example, at a distance of less than 50 mm, 20 mm, or 5 mm from the plasma outlet. The ground electrode may be disposed on a distal portion of the tube. The ground electrode advantageously improves the stability and reproducibility of the generated plasma jets by allowing control of the plasma jets formed at the tube outlet.

[0026] The conductive element is preferably made of a semiconducting material or of a conductive material such as stainless steel.

[0027] It can have any elongated shape allowing it to be placed in the recess of the tube, for example a rod shape, a hook shape, a helical spring shape or even a V shape.

[0028] The conductive element may have a length greater than or equal to 1 mm, 10 mm or 100 mm, and / or less than or equal to 150 mm, 50 mm or 10 mm, in particular between 6 mm and 7 mm. The conductive element may have a diameter greater than or equal to 0.1 mm and / or less than or equal to 5 mm.

[0029] The ratio between the diameter of the section of the conducting element and the diameter of the inner section of the tube, in particular at the level of the conducting element, can be between 0.1 and 0.95. If the section of the conducting element and / or the inner section of the tube are not circular, the diameter is understood to be the diameter of the smallest circle circumscribing these sections.

[0030] A first end of the upstream conducting element is preferably located at the center of the tube in its cross-section. It is positioned longitudinally between the upstream and downstream ends of the high-voltage electrode, preferably within a distance of between 40% and 60% of the distance between the upstream and downstream ends of the high-voltage electrode, and more preferably equidistant from the upstream and downstream ends of the electrode. The distances are measured along the axis of the tube.

[0031] A second end of the conductive element on the downstream side extends beyond the downstream end of the high-voltage electrode, preferably by a length less than 20% or 10% of the length of the conductive element, or greater than or equal to 1 mm, 2 mm or 5 mm and / or less than or equal to 10 mm, 5 mm or 2 mm.

[0032] According to an advantageous feature, the conducting element has one end, which may be the second end, having an acute shape, in particular conical with a conicity angle between 5° and 120°. This strengthens the electric field at the second end and thus facilitates the ionization of the gas.

[0033] Thus, the conductive element extends mainly within the portion of the tube's volume defined by the high-voltage electrode. This allows for coupling, particularly capacitive coupling, between the electrode and the conductive element, transferring electrical power to the conductive element, which is concentrated towards the second end of the conductive element.

[0034] The conductive element is advantageously fixed within the tube or secured in such a way that its position can only vary slightly, for example, by less than 5% of the length of the conductive element. The conductive element may, in particular, be fixed within the tube by fins attached on one side to the conductive element and on the other to the inner wall of the tube, by hooks, or by barrels. It may also be overmolded or inserted into the tube using a cold or hot process.

[0035] According to one embodiment, the conductive element has a nail shape, comprising a head forming a first end of the conductive element and a shank whose free end forms a second end of the conductive element.

[0036] The stem of the conducting element can advantageously be arranged in a portion of the tube shaped to prevent the insertion of the head of the conducting element. In other words, the dimensions of the head of the conducting element are such that the head cannot be inserted into the portion of the tube receiving the stem of the element conductor. In particular, the head of the conducting element may have a maximum diameter greater than the diameter of the stem. Diameters are measured in a plane perpendicular to the axis of the tube.

[0037] The head can be flat or domed. The head can have a circular, oval, square, or rectangular cross-section. The conducting element can be T-shaped, with the head forming a cross-sectional bar.

[0038] Advantageously, the device includes a blocking element comprising at least one protrusion extending into at least one tube upstream of at least one conductive element so as to limit the upstream movement of the conductive element, with respect to the direction of gas flow. Thus, the upstream movement of the conductive element is limited. The head of the conductive element can further limit its downstream movement. The conductive element is thus held in position, optionally with some clearance due to the maximum distance between the downstream end of the protrusions and the head of the conductive element.

[0039] The locking element can be fixedly assembled with at least one tube.

[0040] According to one embodiment of the invention, the tube has a recess with a circular cross-section. The diameter of the recess's cross-section is preferably greater than the diameter of the conducting element to allow the gas and plasma to flow through the tube.

[0041] Alternatively, the tube has a cross-sectional recess comprising a central portion configured to receive and optionally retain the conducting element and one or more secondary portions arranged around the central portion and configured to allow the flow of gas and / or plasma.

[0042] In one embodiment, the tube defines, along at least a portion of the conducting element, a recess whose cross-section is non-circular, preferably multilobed, in particular a three-leaf clover, a four-leaf clover, or star-shaped, in particular a star with three or more points, the conducting element preferably being centered in this recess. A clover shape comprises a central portion for receiving the conducting element and open onto three or more secondary portions forming the leaves, each of which may, in particular, be circular or oval in shape. A star shape comprises a central portion for receiving the conducting element and open onto secondary portions forming the points of the star.

[0043] The recess within the tube can have a cross-section of variable dimensions along the tube, particularly upstream or downstream of the conducting element.

[0044] The tube is in particular made of a non-conductive material, for example a plastic material such as polycarbonate.

[0045] The tube may include a distal portion that includes the plasma outlet and is flared. The flared distal portion may extend over a length, in the direction of plasma flow, of 20 cm or less, preferably 10 cm or less, and more preferably 5 cm or less. The ratio of the maximum diameter of the distal portion to the minimum diameter of the distal portion may be between 1 and 100.

[0046] The tube may have a wall of fixed or variable thickness. In the particular case of a wall of variable thickness, the wall of the distal portion may be wider than the wall upstream of the distal portion. The wall of the distal portion may have a thickness of between 0.1 mm and 5 mm. The ratio of the wall thickness of the upstream portion to the thickness of the distal portion may be between 0.1 and 10.

[0047] A device according to the invention may comprise more than two plasma outlets and / or more than two tubes. Preferably, the number of plasma outlets is between 1 and 100, preferably between 1 and 50, and even more preferably between 1 and 10. In a preferred embodiment of the invention, the device comprises several tubes, each tube being able to comprise several plasma outlets.

[0048] Each tube may have a gas supply inlet. Alternatively, the device may have a single gas supply inlet, fluidly connected to a distribution chamber which is itself fluidly connected to each of the tubes.

[0049] According to an advantageous feature, the device comprises a single gas supply inlet fluidically connected to a distribution chamber, the device comprising a plurality of tubes, for example four tubes, each fluidly connected to the distribution chamber.

[0050] The device according to the invention is optionally configured so that the high-voltage electrode can deliver 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 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 initiation pulse of plasma propagation towards the plasma outlet, the frequency of the second electrical signal being lower than the frequency of the first electrical signal, preferably in a ratio first signal frequency / second signal frequency greater than 1 and less than or equal to 1000, preferably between 3 and 100, better between 5 and 50.

[0051] The second signal advantageously allows for initiating and / or accelerating the propagation of the plasma in the tube. In particular, the second signal allows for adjusting the dose of plasma ejected from the device.

[0052] Plasma dose means the amount of plasma energy transmitted to the target.

[0053] In another embodiment, the first and second electrical signals are delivered via a first high-voltage electrode and a second high-voltage electrode respectively, the first high-voltage electrode being positioned upstream of the second electrode, in the direction of plasma propagation. The second high-voltage electrode may be positioned downstream of the first high-voltage electrode, for example around a distal portion of the tube.

[0054] The invention further relates to a cold plasma jet generation assembly comprising a handle receiving a cold plasma jet device as described above.

[0055] Optionally, the assembly includes a spacer disposed on the handle around at least one plasma outlet and configured to prevent direct contact between the at least one plasma outlet and a surface to be treated, the spacer preferably being removable.

[0056] The invention further relates to a method of generating one or more plasma jets by means of a device as described above, the gas supply inlet being supplied with argon or a mixture of argon and oxygen. Brief description of the drawings

[0057] [Fig-1] The [Fig. 1] represents a plasma jet device according to the invention.

[0058] [Fig.2] Fig.2 is a longitudinal sectional view of the device shown in Fig.1.

[0059] [Fig.3] The [Fig.3] is a side view of the device of the [Fig.1].

[0060] [Fig.4] Fig.4 is a cross-sectional view of the device shown in the [Fig.3],

[0061] [Fig.5] [Fig.5] is a longitudinal cross-sectional view of the device shown in [Fig.3],

[0062] [Fig.6] The [Fig.6] is a cross-sectional view of tubes of a plasma jet device according to the invention.

[0063] [Fig.7] Fig.7 illustrates different cross-sectional variants of tubes for a plasma jet device according to the invention.

[0064] [Fig.8] Fig.8 is a cross-sectional view of a handle comprising a plasma jet device according to the invention.

[0065] [Fig.9] Fig.9 represents a plasma jet generation assembly comprising a plasma jet device according to the invention. Detailed description

[0066] In the rest of the description, identical elements or elements with identical functions bear the same reference sign.

[0067] The terms "upstream," "downstream," "inlet," and "outlet" are defined with respect to the direction of gas and plasma propagation. The terms "inside" and "outside" are defined with respect to the positioning of the plasma relative to the device, the plasma being inside the device. The terms "transverse" and "longitudinal" are defined with respect to the axis of the tubes, which therefore extend in the longitudinal direction.

[0068] Figures 1 to 5 illustrate an embodiment of a plasma jet device 1 according to the invention. Figures 4 and 5 are respectively cross-sectional views of the device in plane AA and longitudinal section in plane BB, planes AA and BB appearing in [Fig. 3].

[0069] The device 1 comprises a lower part 19 and an upper part 18 assembled on the lower part, and extends parallel to an axis X which is oriented from upstream to downstream in the direction of gas and plasma circulation.

[0070] The device 1 includes a tubular gas inlet 2 that allows gas to be injected into the device. The injected gas may, in particular, be a noble gas such as helium, argon, neon, or a gas mixture such as a mixture of argon and oxygen. Preferably, the gas is helium or argon. The gas flow rate may be between 0.2 L / min and 5 L / min, preferably about 1 L / min.

[0071] The gas inlet 2 is fluidly connected to a distribution chamber 3, which is itself fluidly connected to several tubes 4, for example four as illustrated, belonging to the lower part 19. The free ends of the tubes 4 form plasma outlets 5 through which the plasma generated by the device 1 can be ejected.

[0072] The tubes 4 can in particular be straight and extend parallel to the X axis. The tubes 4 are advantageously rigid and made of a non-conductive material, for example of a plastic material such as polycarbonate.

[0073] The device 1 comprises a high-voltage electrode 6 arranged around the four tubes 4, near the distribution chamber 3. The high-voltage electrode 6 is electrically connected to a voltage source. It is configured to generate an electric field in the tubes 4 and thus enable the generation of plasma from the source gas in a plasma generation zone of the tubes.

[0074] The high-voltage electrode 6 surrounds the tubes 4. The upstream and downstream ends of the electrode each define a plane transverse to the X axis.

[0075] The device 1 further includes a ground electrode 13 arranged around the four tubes 4, near the plasma outlets 5. The ground electrode 13, which is connected to the electrical ground, advantageously improves the stability and reproducibility of the plasma jets.

[0076] An electrically conductive element 7, made of conductive or semiconducting material, is arranged in each of the tubes 4.

[0077] According to one embodiment, the ground electrode electrically connected to ground forms, with the high-voltage electrode, a capacitor so that the coupling with the conducting element is capacitive.

[0078] According to another embodiment, the high-voltage electrode is in the form of a coil, one end of which is electrically connected to a voltage source and the other end is electrically connected to an electrical ground, so that the coupling with the conducting element is inductive.

[0079] Preferably, as illustrated, there is an axial overlap along the X axis between each conductive element 7 and the high-voltage electrode 6. The conductive elements 7 have a floating electrical potential: they are not in electrical contact with an element with a fixed potential.

[0080] As particularly visible in [Fig.2], a conductive element 7 may have a head 8 arranged in the extension of a rod 9, the head 8 being dimensioned so as not to be able to penetrate into the portion of the tube 4 which receives the rod 9. Thus, the head 8 prevents the conductive element 7 from moving in the tube in the downstream direction.

[0081] The conductive elements 7 can have a length between 1 mm and 150 mm and / or a diameter between 0.1 mm and 2 mm.

[0082] The conductive elements 7 can in particular be made of stainless steel, a material resistant to corrosion and oxidation, biocompatible, easy to sterilize, inert, strong and durable.

[0083] The free end of the rods 9 is advantageously acute, i.e. tapered, for example conical in shape with a conicity angle between 5° and 120°.

[0084] Other forms of conductive elements are also conceivable.

[0085] The device 1 may include a blocking element 10 comprising a main part 11 arranged in the distribution chamber 3 and protrusions 12 which each extend into a tube 4.

[0086] The main part 11 is fixed to the device 1, for example by screws or by clips, and the protrusions 12 extend into the tubes so that the free ends of the protrusions are close to the heads 8 of the conducting elements 7. The protrusions 12 thus limit the movement of the conducting elements in the upstream direction.

[0087] The locking element 10 and the heads 8 of the conductive elements 7 thus make it possible to lock the conductive elements 7 in their position within the tubes 4 in both the downstream and upstream directions. The conductive elements 7 may, however, have limited play along the X-axis, for example between 1 mm and 12 mm, corresponding to the maximum distance between the free end of the protuberances 12 and the heads 8 of the conducting elements 7.

[0088] The locking element 10 can be made of a plastic material such as polycarbonate.

[0089] Other means of blocking or retaining the conductive element may be considered.

[0090] The high-voltage electrode 6, not shown in figures 2 to 5, is arranged around the tubes 4 over a height H.

[0091] The heads 8 of the conducting elements 7, which form a first end of the conducting elements 7, are preferably as illustrated arranged at mid-height of the height H, that is to say at an equal distance along the axis X from the upstream and downstream ends of the high-voltage electrode 6.

[0092] As particularly visible in [Fig.2], the rods 9 of the conducting elements 7 extend beyond the downstream end of the high-voltage electrode 6 along the X axis. Thus, the free ends of the rods 9, which form a second end of the conducting elements 7, are arranged downstream of the high-voltage electrode 6.

[0093] Preferably, the free ends of the rods 9 extend beyond the high-voltage electrode 6 by a length along the X axis greater than or equal to 1 mm, 2 mm or 5 mm and / or less than or equal to 10 mm, 5 mm or 2 mm.

[0094] An advantageous embodiment of the tubes 4 has been illustrated in [Fig.6]. [Fig.6] is a cross-sectional view of four tubes 4.

[0095] Each tube 4 has a recess 40 which receives a conducting element 7 and allows the gas and plasma to flow from upstream to downstream. In the illustrated example, the recess 40 has a three-leaf clover-shaped cross-section with a central portion 41, generally circular in cross-section, receiving the stem 9 of a conducting element 7 and three secondary portions, or channels, 42 arranged around the central portion 41 and open onto it. The channels 42 are distributed equiangularly around the central portion 4L

[0096] Figure 7 shows the cross-sections of other embodiments of tubes 4. In these embodiments, a tube 4 has a recess 40 whose cross-section is in the shape of a four-, five-, six-, or seven-pointed star. At the center of the star, the dimensions of the recess are adapted to receive the rod 9 of a conductive element 7.

[0097] The recesses within the tubes can have a constant or variable cross-section along the X axis. Thus, the cross-section of the recess in a tube can have variable dimensions along the X axis.

[0098] By way of example, a recess with a circular cross-section may have a larger diameter in an upstream part of the tube that receives the conducting element 7 that in a downstream part, the diameter being for example between 1 mm and 5 mm in the upstream part and between 0.1 mm and 3 mm in the downstream part.

[0099] Similarly, the cross-section of a more complex shaped recess, such as a multi-pointed star or a three- or four-leaf clover, may have different dimensions along the X axis.

[0100] Fig. 8 represents a plasma jet device 1 according to the invention arranged in a handle 20, in longitudinal section view.

[0101] The handle 20 facilitates gripping and use of the device 1. The handle 20 comprises a housing 21 which receives the device 1, a gas inlet tube 22 fluidly connected to the gas inlet 2, and an electrical power cable 23 having a first wire 24 electrically connected to the high-voltage electrode 6 and a second wire 25 electrically connected to the ground electrode 13. A spacer 25 is advantageously fixed to the handle 20 so as to surround the free ends of the tubes 4. The spacer 25 extends beyond the plasma outlets 5 in the downstream direction, so that physical contact between the tubes 4 and the surface to be treated is prevented by the presence of the spacer 25.

[0102] The spacer 25 is preferably removable so that it can be changed after each use. The spacer 25 is, for example, mounted on the handle 20 by clipping (spring clips, fixing clips), by bayonet locking, by snapping or by screwing.

[0103] Figure 9 shows an example of a cold plasma jet generation assembly 100, comprising a handle 20, which includes a cold plasma jet device 1, connected to a housing 101 by a single cable 102. The cable 102 contains the power supply cable 22 and the gas supply tube 21. The housing 101 advantageously includes a control interface 103. Functioning

[0104] The operation of a plasma jet device 1 according to the invention follows directly from the above.

[0105] A source gas, which may in particular be a rare gas such as argon or helium, enters the device 1 through the gas supply inlet 2. The gas, which is typically at room temperature, then enters the distribution chamber 3 from which it is distributed into the various tubes 4.

[0106] The high-voltage electrode 6, which is electrically connected to a voltage source, delivers a first electrical signal which generates an electric field in each of the tubes 4. The electric field tends to concentrate at the downstream end of the conducting elements 7 and allows the plasma to be initiated.

[0107] The conductive elements 7 facilitate the initiation of the plasma, in particular by allowing the concentration of the electric field at the free end of the rods 9.

[0108] The first electrical signal may, in particular, have a frequency between 50 Hz and 100 kHz, preferably between 5 kHz and 50 kHz, for example approximately 10 kHz or 20 kHz. It may, in particular, have a voltage between 1 kV and 30 kV, preferably between 5 kV and 10 kV, for example approximately 5 kV or 7 kV.

[0109] Optionally, the high-voltage electrode 6 can deliver a second electrical signal adapted to promote the propagation of the generated plasma towards the plasma outlets 5.

[0110] When the plasma reaches the plasma outlets 5, it forms one or more jets that can be used to treat a surface.

[0111] As is now clear, a device according to the invention makes it possible to considerably reduce the voltage required to initiate the plasma, which facilitates the use of different gases, particularly argon, which requires a higher initiation voltage than helium. Furthermore, the reduction in the initiation voltage advantageously reduces the electromagnetic noise generated by the device.

[0112] The use of a plurality of tubes 4 increases the treatment area. Furthermore, a low plasma dose may be sufficient, particularly by using a frequency between 7 kHz and 20 kHz for the field generated by the high-voltage electrode. The device according to the invention therefore improves the treatment speed, making it possible, for example, to obtain treatment times on the order of 4 s per cm² compared to 30 s to 60 s per cm² for existing devices.

[0113] The ground electrode also ensures good homogeneity of the powers and shapes of the plasma jets.

[0114] A device according to the invention is particularly advantageous for the treatment of chronic wounds, such as ulcers, diabetic foot ulcers, and bedsores, for the treatment of burns, for example, for treating severe burns, as well as for cosmetic applications, such as the treatment of acne. In general, such a device is suitable for treating all types of wounds.

[0115] Of course, the invention is not limited to the embodiments just described.

[0116] In particular, a device according to the invention may include a safety system configured to control the plasma dose ejected from the device, and / or control the delivered current, and / or control the temperature of the plasma at the device outlet, and / or control the plasma power, and / or control the rare gas pressure in a rare gas cylinder supplying the rare gas inlet of the tube, and / or control the rare gas pressure in the tube. For example, the safety system may be a fast circuit breaker, or a microcontroller control of the high-voltage power supply to the electrode that generates the plasma.

[0117] A device according to the invention preferably includes redundancy, in particular to comply with regulations concerning medical devices.

[0118] 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 / Al:2018, 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.

[0119] The device illustrated in the figures has four tubes, but the invention applies to a different number of tubes, for example 1, 2 or 3.

[0120] The expression "comprising one" should be understood as a synonym of "comprising at least one".

Claims

Demands

1. Cold plasma jet device (1) comprising: - at least one gas supply inlet (2); - at least one tube (4) fluidically connected to the gas supply inlet and comprising at least one plasma outlet (5), the gas supply inlet and the plasma outlet defining a direction of gas and plasma flow; - at least one high-voltage electrode (6) outside the tube configured to generate an electric field in the tube; and - at least one electrically conductive element (7) having a floating electric potential and extending axially inside the tube at least partially between the high-voltage electrode and the plasma outlet.

2. Device according to claim 1, the high-voltage electrode surrounding the tube.

3. Device according to claim 1 or 2, the conducting element and the high-voltage electrode partially overlapping axially.

4. Device according to any one of the preceding claims, comprising a ground electrode (13) connected to electrical ground and disposed around the outer wall of the tube, at a distance from the outlet less than that separating the high-voltage electrode from the outlet, downstream of said conductive element, preferably in close proximity to the plasma outlet.

5. Device according to any one of the preceding claims, the conductive element having a nail shape, comprising a head (8) forming a first end of the element and a shank (9) the free end of which forms a second end of said element.

6. Device according to any one of the preceding claims, the conducting element having an end having an acute shape, in particular conical with a taper angle between 5° and 120°.

7. Device according to any one of the preceding claims, comprising a blocking element (10) including at least one protrusion (12) extending in the tube upstream of said conducting element, so as to limit the upstream movement of the conducting element, having regard to the direction of gas flow.

8. Device according to any one of the preceding claims, the tube defining along at least a portion of the conducting element a recess (40) whose cross-section is non-circular, preferably multilobed, in particular of a three-leaf clover, of a four-leaf clover, or star-shaped, in particular of a star with three or more points, the conducting element being preferably centered in this recess.

9. Device according to any one of the preceding claims, the tube having a variable internal cross-section along the tube, particularly upstream or downstream of the conducting element.

10. Device according to any one of the preceding claims, comprising a single gas supply inlet fluidly connected to a distribution chamber (3), the device comprising a plurality of tubes each fluidly connected to the distribution chamber.

11. Cold plasma jet generation assembly (100) comprising a handle (20) receiving a cold plasma jet device according to any one of the preceding claims.

12. Assembly according to the preceding claim, comprising a spacer (25) disposed on the handle around at least one plasma outlet and configured to prevent direct contact between the at least one plasma outlet and a surface to be treated, the spacer preferably being removable.

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