WO2014132216A1

WO2014132216A1 - Device and method for generating cold plasma.

Info

Publication number: WO2014132216A1
Application number: PCT/IB2014/059300
Authority: WO
Inventors: Vittorio Colombo; Matteo GHERARDI; Paolo SANIBONDI; Romolo LAURITA; Augusto STANCAMPIANO; Anna LIGUORI
Original assignee: Alma Mater Studiorum - Universita' Di Bologna
Priority date: 2013-02-28
Filing date: 2014-02-27
Publication date: 2014-09-04
Also published as: ITBO20130087A1; EP2961438A1

Abstract

A device (1 ) for generating cold plasma for treating a three-dimensional surface using a "dielectric barrier discharge" technique, comprises an electrode (4) connectable to a high-voltage generator (5) and a layer (3) of deformable dielectric material, having a first face coupled to the electrode (4) and a second face juxtaposable with the surface to be treated, the latter defining a counter-electrode; the electrode (4) is made from a liquid or semi liquid material with low electrical resistivity and the dielectric layer (3) is made from a material which is impermeable to that liquid.

Description

DESCRIPTION

DEVICE AND METHOD FOR GENERATING COLD PLASMA Technical field

This invention relates to a device for generating cold plasma. Background art

The invention relates to a system for generating "cold" plasma, otherwise known as "non-thermal" plasma.

"Cold" or "non-thermal" plasma is plasma at a relatively low temperature, for example, approximately 40°C.

This type of plasma lends itself to the direct treatment of surfaces such as human body skin or other biological surfaces.

It should be noted that in recent years, sources of non-thermal plasmas have been designed and developed for biological and medical applications. For these applications, the maximum effectiveness of the biological treatment can be obtained by direct exposure of the substrate to be treated to the plasma.

As regards systems for generating cold plasma, the use of technology called "DBD" - an acronym for "Dielectric Barrier Discharge" - is known. DBD technology involves generating the plasma in a region of space (typically a gap) adjacent to the surface of a dielectric covering an electrode. Also used is a source of high voltage to create in that region of space an electric field such as to generate the plasma by establishing a potential difference between that electrode and a secondary electrode, also known as counter-electrode.

In the context of DBD systems where the plasma is used to treat the surface of a part, the electrode covered by the dielectric is connected to the high voltage source and the potential difference between the electrode and the selfsame part to be treated is used to generate the electric field. In such cases, therefore, the counter-electrode of the DBD system is the part to be treated.

Patent documents US2009/0054896, US8103340 and WO201 1/1 16984A2 provide examples of devices for generating cold plasma using DBD technology, where the part to be treated constitutes a counter-electrode. These devices, however, are not particularly suitable for treating three- dimensional surfaces which are irregular and varied in shape as is human body skin.

Indeed, the dielectric surfaces of these devices are stiff and cannot be adapted to the specific surface to be treated.

From the patent document DE19532105A1 it is known another example of a cold plasma generation device with DBD technology; such a device has a surface that, in a preparation phase of the device, prior to use of the device itself on the surface to be treated, can be assigned a desired, predetermined shape by thermo-forming, in order to fit three-dimensional surfaces to be treated.

However, even such a device is unsuitable for the treatment of three- dimensional surfaces which are mutable and irregular, non pre-determined in shape, such as those formed from the skin of the human body; in fact, such a device is not able to adapt during use, dynamically, to the conformation of the surface to be treated. Indeed, in use the outer surface of the device DE19532105A1 is rigid and maintains the pre-set shape. In light of this, it should be noted that to prevent the plasma treatment from causing discomfort or damage to the surface to be treated, the plasma must be generated in a sufficiently diffuse manner.

This condition occurs if the electric field in the zone where the plasma is generated is uniform and the gap between the dielectric surface and the treated surface is substantially uniform and relatively small (to prevent the plasma from adopting too intense a form, with localized, repeated and potentially harmful events). In effect, if the gap between the surface to be treated and the dielectric surface is not uniform, the plasma generated between the two surfaces does not have the required uniformity. This problem is tackled in patent document US2012/0259270, which proposes making the dielectric surface and the electrode coupled thereto using a flexible, multi-layer structure, where the electrode is a flexible, planar structure inserted in a dielectric layer made of a flexible material. This solution, too, however, is not entirely problem free.

Indeed, this solution is constructionally complicated. Moreover, it involves the risk of triggering electrical discharges between the conductive layer (electrode) and the dielectric layer, with the consequent risk of weakening the device and losing in efficiency.

Disclosure of the invention

The aim of this invention is to provide a device for generating non-thermal plasma for treating a three-dimensional surface using a "dielectric barrier discharge" technique and which overcomes the above mentioned disadvantages of the prior art.

More specifically, this invention has for an aim to provide a device for generating non-thermal plasma for treating a three-dimensional surface using a "dielectric barrier discharge" technique and which is simple to construct and reliable.

Another aim of the invention is to provide a device for generating nonthermal plasma for treating a three-dimensional surface using a "dielectric barrier discharge" technique and which can be used to sanitize the hands in a particularly effective and convenient manner.

These aims are fully achieved by the device according to the invention as characterized in the appended claims.

More specifically, the device according to the invention comprises an electrode which is connectable to a high voltage source (comprising a high voltage generator) and a layer of deformable dielectric material, having a first face coupled to the electrode and a second face juxtaposable with the surface to be treated, the latter defining a counter-electrode (in the DBD system); the term "deformable" means that the layer of dielectric material can change its shape during its normal use; in other words, the layer of dielectric material may alter its shape in response to a pressure exerted on it, so that the liquid (i.e. the liquid electrode) in contact with it can occupy volumes of different shape, as an effect of the deformation itself.

In this light, it is observed that the layer of dielectric material is deformable in a reversible way, even when cold, or at room temperature or during use in contact with the surface to be treated.

In fact, the layer of dielectric materia! is soft; it is flexible.

According to the description, the electrode is made of a liquid material. The term "liquid" means a material which, under standard conditions of temperature and pressure, is in the liquid phase.

Further, the liquid material may have different viscosity values. For example, the liquid electrode might be a paste.

Further, the liquid electrode is made of a material with low resistivity (that is, electrical resistivity).

Further, the dielectric layer is made of a material which is impermeable to that liquid.

The DBD structure with a liquid electrode has several applications.

A first application regards sanitization of the hands (or other parts of the body or other objects) by generating plasma in the region of space surrounding the surface of the hands.

A second possible application is skin treatment on different parts of the body, for example, the elbows, the back of the knee, etc., by applying plasma in contact with the part of the skin to be treated.

In the case of the first application, the device preferably comprises a vessel filled with the liquid electrode.

The vessel defines at least one opening into which a glove (or other similar object able to receive a hand) can be inserted.

The part of the glove which receives the hand is positioned inside the vessel. Thus, the glove is at least partly immersed in the liquid electrode.

The glove opening into which the hand can be inserted is accessible from the outside of the vessel without coming into contact with the liquid electrode (which is live).

For example, the part of the glove defining the opening is positioned outside the vessel.

The first face of the dielectric layer defines the outside surface of the glove.

The inside surface of the glove (and more specifically, the at least one glove portion positioned inside the vessel) defines the second face of the dielectric layer.

Thus, it should be noted that the glove constitutes a dielectric container which substantially completely surrounds the part to be treated and prevents the formation of a plasma arc.

In the case of the second application, the first face of the dielectric layer preferably defines the inside surface of a sealed container filled with the liquid electrode.

Thus, the container contains the liquid electrode and externally defines the surface which is intended to be juxtaposed (partly also in contact) with the surface to be treated.

The dielectric layer is deformable, so that the shape of the dielectric can be adapted to the shape of the surface to be treated.

More specifically, the dielectric layer preferably has at least one elastic portion (having a particularly high stretch capability) to facilitate deformation of the container when it is pressed against the surface to be treated in order to adapt it to the shape of the surface to be treated.

The invention therefore also provides a method for treating a three- dimensional surface with non-thermal plasma generated using the DBD technique.

The method comprises the following steps:

- preparing an electrode connected to a high-voltage generator;

- preparing a layer of deformable dielectric material having a first face which is coupled to the electrode; - juxtaposing a second face of the dielectric layer with the surface to be treated, defining a counter-electrode, or vice versa.

According to the invention, the electrode is made of a liquid or semi liquid material with low resistivity.

Further, the dielectric layer is made of a material which is impermeable to the liquid constituting the electrode.

In the case of the first application, the first face of the dielectric layer defines an outside surface of a glove which is partly immersed in the liquid electrode and whose opening is accessible from the outside of the liquid electrode, the juxtaposing step comprising inserting the surface to be treated into the glove.

In the case of the second application, the first face of the dielectric layer defines the inside surface of a sealed container filled with the liquid electrode and has at least one elastic portion, the juxtaposing step comprising pressing the second face of the dielectric layer against the surface to be treated to deform it in such a way that it adapts to the shape of the surface to be treated.

It should be noted that the high voltage source is configured to supply alternating or pulsed voltage.

The dielectric layer is deformable (flexible). More specifically, it is designed to become deformed upon touching a contact surface defined by the counter-electrode to adapt to the profile thereof.

Preferably, the second face of the dielectric layer (that is, the face directed towards the surface to be treated) is covered by spacers which help to form gaps between the layer of dielectric material and the surface to be treated, where the plasma can be generated.

It should be noted that the treated material may, in principle, be of any type, for example biological, inorganic, metallic or polymeric.

In light of this, in some applications (for example when the object to be treated is metallic) the liquid electrode might be connected to earth and the object to be treated to the high-voltage generator. The device is a portable device and preferably also comprises the high- voltage generator (for example, it is also equipped with a battery).

It should also be noted that, in addition to the (first) liquid electrode contained in the (first) dielectric layer, the device might also comprise a second liquid electrode contained in a second dielectric layer.

The corresponding outside surfaces of the two dielectric layers may be juxtaposed to define a gap in which the plasma is generated.

Operatively, therefore, the object to be treated is interposed between the two assemblies comprising the liquid electrode and the respective dielectric containment layer.

At least one of the dielectric layers, but preferably both of them, is deformable (preferably elastically flexible).

Operatively, the first and second liquid electrodes may both be connected to earth, while the object to be treated is connected to the high-voltage source.

Alternatively, the first and second liquid electrodes may both be connected to the high-voltage source, while the object to be treated is connected to earth. Brief description of drawings

This and other features will become more apparent from the following description of a preferred embodiment, illustrated purely by way of non- limiting example in the accompanying drawings, in which:

- Figure 1 illustrates a device according to this invention, in a first embodiment;

- Figure 2 illustrates a device according to this invention, in a second embodiment;

- Figures 3-5 illustrate further examples of embodiments of a device according to this invention. Detailed description of preferred embodiments of the invention

The numeral 1 in the drawings denotes a plasma generating device according to the invention.

The device 1 is a device for generating non-thermal plasma (also known as "cold" plasma) for treating the surface of a part 2.

Generally speaking, the surface is a three-dimensional surface (that is, a non-planar surface).

The device 1 has an architecture of the "dielectric barrier discharge" (DBD) type.

Further, more specifically, the device 1 is configured in such a way that during the operation of the device the surface to be treated acts as a counter-electrode.

More specifically, the device 1 comprises a dielectric layer 3, that is, a layer of dielectric material.

For example, the layer 3 is made of natural rubber or PVC.

The dielectric layer 3 is deformable, in order to allow the layer 3 itself to adapt to the different shapes of the surfaces to be treated.

The device 1 also comprises an electrode 4 connectable to a generator 5

(that is, a source) of high voltage.

Preferably, the generator is configured to generate an alternating voltage at 50 or 60 Hz. Also, preferably, the generator is configured to establish a potential difference of approximately 3-10 kV.

According to the invention, the electrode 4 is made of a liquid or semi- liquid material (as, for example, silver paste). Thus, the electrode 4 is a liquid electrode.

The liquid material has low resistivity, preferably less than 105 Ω/m.

For example, the liquid electrode 4 is made from one of the following materials: water (from the tap), salt water, conductive paste, silver epoxy resin or Galinstan.

In light of this, the dielectric layer 3 is made of a material which is impermeable to that liquid. The dielectric layer 3 has a first face which is coupled to the electrode 4. More specifically, the liquid electrode 4 is in contact with the first face of the dielectric layer 3 (or with a part thereof).

The dielectric layer 3 has a second face which is juxtaposable with the surface to be treated.

Operatively, the surface (that is, the part 2) to be treated defines a counter-electrode, in the DBD system, in such a way that the generator 5 generates an electric field by effect of a potential difference between the electrode 4 and the counter-electrode.

It should be noted that, at least for some applications, the counter- electrode might be connected to the generator 5 and the liquid electrode 4 to earth.

Preferably, the second face of the dielectric layer 3 is provided with a plurality of protrusions 6, for example bosses (hemispherical in shape) or protuberances of other shapes.

In addition or alternatively to the protrusions 6, the second face of the dielectric layer 3 might be provided with cavities, grooves or recesses. The function of the protrusions 6, or the cavities, is to create a plurality of empty (that is, air-filled) interstices or gaps in which the plasma can be generated when the dielectric layer 3 is juxtaposed or placed in contact with the surface to be treated.

Operatively, a relative movement (for example, by wiping) between the dielectric layer 3 and the surface to be treated allows the plasma to cover the entire surface to be treated, even if a part of the second face of the dielectric layer 3 remains in contact with the surface to be treated.

For example, in the case of the protrusions 6, the ends of the protrusions 6 are operatively in contact with the surface to be treated and the plasma is formed in the zones adjacent the protrusions. In the case of the cavities, the portions of the second face of the dielectric layer 3 situated between one cavity and another are operatively in contact with the surface to be treated and the plasma is formed inside the cavities. Thus, the protrusions 6 and the cavities define spacer elements. These spacer elements are made of a dielectric material which may be the same material as that of the dielectric layer 3 or a different material. The purpose of the spacers is to create a plurality of gaps in which the plasma is generated. Another purpose is to obtain a particularly high value of the electric field inside the gaps.

Preferably, the protrusions 6 and the cavities are configured in such a way that the size of the gaps is in an interval of several tenths of a micron to a few centimetres.

The spacers may be permanently fixed to the dielectric layer 3 or placed fixedly or removably on a further layer.

In a first embodiment of it, the device 1 is a device for sanitizing the hands. In this embodiment, the first face of the dielectric layer defines an outside surface of a glove 7 (or similar object, shaped to receive a hand).

Thus, the protrusions 6 or cavities are directed inwardly of the glove 7.

The glove is immersed (wholly or partly) in the liquid electrode 4. The glove opening 8 is positioned in such a way as to be accessible from the outside of the liquid electrode 4.

Preferably, the device 1 comprises a vessel 9 filled with the liquid electrode 4.

In practice, the glove seals the vessel 9, in the sense that the dielectric layer 3 constituted by the glove 7 forms a separating wall between the liquid electrode 4 inside the vessel 9 and the atmosphere outside the selfsame vessel 9.

More specifically, the part of the glove 7 which receives the hand is positioned inside the vessel 9.

The glove 7 also has a part (defining the opening 8 in the glove 7 through which the hand can be inserted into the glove 7) which is positioned outside the vessel 9 (so it is not in contact with the liquid electrode).

In any case, the opening 8 of the glove 7 is accessible from the outside of the vessel 9. It should be noted that the vessel 9 defines a box-shaped element defining a space (within the box-shaped element itself).

The glove 7 defines a portion of that space, that portion being occupiable by a hand and being delimited by the dielectric layer 3.

Thus, the dielectric layer 3 acts in conjunction with a wall of the vessel 9 to form a closed surface containing the liquid electrode 4 .

Preferably, the device 1 comprises two (or more) of the gloves 7.

Preferably, the device 1 comprises (at least) two gloves inside the same vessel 9 and positioned in such a way as to reduce (minimize) the overall dimensions of the vessel (and the volume of the liquid electrode 4).

For example, the gloves 7 are positioned with the palms substantially parallel. Preferably, the gloves 7 are positioned with the palms facing each other. This makes it possible to reduce the overall dimensions of the vessel 9, giving the vessel 9 a compact form.

It should also be noted that the gloves 7 are preferably positioned with the palms substantially parallel to side walls of the vessel 9, these side walls facing the back or the palm of the gloves 7.

This allows particularly efficient use of the space defined inside the vessel 9, with the possibility of giving the vessel 9 forms which allow the user's hands to be held in a comfortable, natural position during sanitization.

Preferably, the device 1 comprises a switch 10 to connect and disconnect the liquid electrode 4 to and from the high voltage generator 5.

Preferably, the device 1 comprises a pedal 1 1 (or other control operable without the hands, for example a microphone able to receive a voice command) used to operate the switch 10 (in order to make and break an electrical circuit connecting the liquid electrode 4 to the high voltage source 5).

The numeral 12 in Figure 1 denotes a control unit (for example, an electronic board) connected to the switch 10 and to the pedal 1 1.

Preferably, the opening 8 of the glove (or gloves if there are two or more) is reversibly deformable (for example, elastically) to reduce or enlarge the size of the opening 8 itself to receive the hand.

The purpose of this is to prevent any harmful gases (in particular ozone) produced inside the glove during (or after) treatment of the hand from escaping to the atmosphere and, in particular, from being breathed in by the person whose hands are being sanitized.

In light of this, the device 1 preferably also comprises an actuator configured to deform the end of the glove 7 (the end defining the opening 8) between a first configuration, where the opening 8 of the glove 7 is wide open to allow the hand to be inserted into it, and a second configuration, where the opening 8 of the glove 7 is tightly closed to prevent gas from escaping from the glove 7.

Preferably, the actuator (schematically illustrated in Figure 1 , where it is labelled 13) is connected to the control unit 12. The actuator 13 is, for example, pneumatic.

The device 1 preferably also comprises a duct (not illustrated, consisting for example of one or more pipes, made preferably of dielectric material, and preferably flexible) in communication with the space inside the glove 7 and connected to an extractor (for example, a pump) or other means for removing ozone or other unwanted gases from the space inside the glove 7.

Preferably, the device comprises a (further) box-shaped element connected to the duct and designed to receive the gas extracted from the inside of the glove. This allows the ozone to be returned safely to the atmosphere after recombination. In light of this, filtering elements are also provided which operate inside the space in the box-shaped element to facilitate and speed up breakdown and recombination of the ozone.

Preferably, the extractor, too, is connected to the control unit 12.

In light of this, the control unit is preferably configured to turn on the actuator (which deforms the glove opening 8), the switch 10 and the extractor automatically and in synchronized manner (in sequence) in response to an action taken by the user (for example with the pedal 1 1 ). For example, operatively, a person wishing to sanitize his/her hands inserts them into the gloves 7 and then operates the pedal 1 1 (or other control means).

This action activates the control unit 12, which drives the actuators 13 to tighten the openings 8 of the gloves 7 in such a way that they close the hands inside the gloves, sealing them off from the outside atmosphere.

At the same time, or after that, the control unit 12 closes the switch 10, preferably for a preset time interval (for example, 30 seconds).

After that, the control unit 12 re-opens the switch 10 (preferably automatically or, alternatively, through the agency of control means which can be operated by the user without using his/her hands).

The control unit 12 also activates the extractor and then issues the command to widen the openings 8 of the gloves 7.

In a second embodiment, the device 1 is a hand-held instrument used to treat a surface by juxtaposing the device 1 itself (preferably by pressing it gently against) the surface to be treated.

In this embodiment, the first face of the dielectric layer 3 preferably defines the inside surface of a sealed container 14 filled with the liquid electrode 4. In that case, preferably, the dielectric layer 3, besides being deformable, has at least one elastic portion (preferably having a particularly high stretch capability).

For example, the container 14 has a highly deformable, elastic membrane 15 (dielectric).

Thus, when the dielectric layer 3 is pressed into contact with the surface to be treated, the container 14 is deformed and adapts more easily to the shape of the surface to be treated.

The invention therefore also provides a method which can be used to treat a three-dimensional surface with non-thermal plasma generated using the "dielectric barrier discharge" technique and which comprises the following steps:

- preparing the liquid electrode 4 connected to a high-voltage generator 5; - preparing the layer 3 of deformable dielectric material which is impermeable to the liquid constituting the electrode 4 and which has a first face which is coupled to (in contact with) the electrode 4 itself;

- juxtaposing a second face of the dielectric layer 3 with the surface to be treated, defining a counter-electrode, or vice versa (in the sense that the surface to be treated can be moved towards the dielectric layer 3).

It should also be noted that (depending on the type of application), the part 2 can be connected to the generator 5 and the liquid electrode 4 can be connected to earth.

In the first embodiment, constituting a first possible application of the method according to the invention, the method is a method for sanitizing the hands.

In this embodiment, the first face of the dielectric layer 3 defines the outside surface of the glove 7, which is partly immersed in the liquid electrode 4 and whose opening 8 is accessible from the outside of the liquid electrode 4.

The juxtaposing step comprises inserting the hand into the glove 7.

Further, during application of the plasma to the hand (when the generator 5 is connected up and creates the electric field) the method preferably also comprises moving the hand inside the glove in order to facilitate applying the plasma uniformly to the entire surface of the hand.

In the second embodiment, constituting a second possible application of the method according to the invention, the method is a method for treating an irregular, three-dimensional surface (for example, the surface of any of several different parts of the human body) by adapting the shape of the device 1 (in particular of the dielectric layer 3) to the shape of the surface to be treated in each case.

In this embodiment, the first face of the dielectric layer 3 preferably defines the inside surface of the sealed container 14 filled with the liquid electrode 4.

The juxtaposing step comprises pressing the second face of the dielectric layer 3 on the surface to be treated to deform the dielectric layer 3 in such a way as to adapt it to the shape of the surface to be treated.

According to the present description, for additional applications or embodiments of the device of cold plasma generator are provided, according to the following examples.

In a first example of possible embodiment, the device comprises a closed box-shaped body containing the liquid electrode 4.

At least a top wall of the box-shaped body 3 is defined by the layer of dielectric deformable (or flexible) material; a remaining portion of the outer wail of the box body is constituted by a frame of the box-shaped body itself.

In this way, the device defines a bearing, formed by the layer 3 of deformable dielectric material, on which a person can place a hand, alternately with the palm and with the back, for sterilizing the hand through the cold plasma.

The outer surface of the layer 3 of deformable dielectric material, intended to come into contact with the hand, is provided with the plurality of protrusions 6 and / or recesses.

In a second example of possible embodiment, the device comprises a structure having a first portion and a second portion articulated reciprocally to allow a relative movement between a closed position and an open position (for example, with a book-like movement) .

The layer 3 of deformable (or flexible) dielectric material has at least a first face coupled to the first part of the structure and a second face coupled to the second part of the structure.

In this way, it is defined a first and a second bearing, reciprocally movable between the open position and the closed position.

Operationally, the person positions his hand (or hands) with the back or the pole leaning against the first bearing, with the structure in the open position; then the structure moves in the closed position so that the hand is interposed between the two bearings, palm and back simultaneously in contact with the respective faces of the layer 3 of deformable (flexible) dielectric material.

This allows you to sanitize your hand in a particularly quick and effective manner,

Alternatively, said articulation of the structure could be replaced by a rigid connection or an elastic connection between the two parts of the structure; in this case, the two bearings are always positioned in a mutually approached position, to define a slot (interspace, fissure) in which the hand can be introduced. Preferably, the device is configured to generate an interference with the hand inserted in said interspace; such interference is compensated for by the deformabiiity (or flexibility) of the layer 3 of dielectric material and possibly by the elastic connection between two parts of the structure.

Also in this embodiment, the areas of the outer surface of the third layer 3 of dielectric material deformable intended to enter into contact with the hand are equipped with the plurality of projections 6 and / or recesses. In a further example of possible embodiment, the device comprises a structure defining a passage (or slit) having an opening through which a hand can be inserted within the same passage.

The structure has at least two opposing walls to define the passage or slit. Preferably, in a first zone of the walls, proximal to the opening, there are nozzles connected to a compressed air generator, to generate jets (for example in the form of blades) to direct air inside the passage, to intercept the hand inserted in the passage itself.

In a (second) area of the walls (distal to the opening), there are a first and a second surface of the layer 3 of deformable (flexible) dielectric material, to form a slot (interspace, fissure); for example said slot is formed by two bearings pushed together, preferably so as to generate interference with one hand introduced between the bearings themselves; in such a way, a hand can be inserted in the slot to be sanitized with cold plasma.

Also in this embodiment, the areas of the outer surface of the third layer of dielectric material deformable intended to enter into contact with the hand are equipped with the plurality of projections 6 and / or recesses.

Operationally, the person, progressively inserting the hand in the passage, first obtains the hand to effect drying of air jets, and subsequently obtains a sanitizing effect through the plasma, by moving the hand further in the passage through the opening, to insert the slot. As regards the particular embodiments of the slot (interspace between surfaces of the dielectric layer 3), for example, the solutions described above in the second example of embodiment can be adopted.

!n all the embodiments described above, the layer 3 of dielectric material is deformable in contact with the electrode 4 liquid.

Claims

1 . A device (1 ) for generating cold plasma for treating a three- dimensional surface using a "dielectric barrier discharge" technique, comprising:

- an electrode (4) connectable to a high-voltage generator (5);

- a layer (3) of deformable dielectric material, having a first face coupled to the electrode (4) and a second face juxtaposable with the surface to be treated, the latter defining a counter-electrode;

characterized in that the electrode (4) is made from a liquid material with low electrical resistivity and the dielectric layer (3) is made from a material which is impermeable to that liquid.

2. The device according to claim 1 , wherein the second face of the dielectric layer (3) is provided with a plurality of protrusions (6) and/or cavities.

3. The device according to either of the preceding claims, wherein the first face of the dielectric layer (3) defines an outside surface of a glove (7) which is at least partly immersed in the liquid electrode (4) and having an opening (8) that is accessible from the outside of the liquid electrode (4).

4. The device according to claim 3, comprising a vessel (9) filled with the liquid electrode (4) and defining at least one opening into which the glove (7) is inserted, in such a way that the part of the glove (7) designed to receive a hand is positioned inside the vessel and the part of the glove (7) defining the opening (8) is accessible from the outside of the vessel.

5. The device according to claim 4, wherein the vessel (9) defines a box-shaped element defining a space, the glove (7) defining a portion of that space which is occupiable by a hand and which is delimited by the dielectric layer (3), the dielectric layer (3) acting in conjunction with a wall of the vessel (9) to form a closed surface containing the liquid electrode (4).

6. The device according to claim 4 or 5, comprising two gloves (7) placed in the same vessel (9) and positioned with the palms parallel.

7. The device according to any of the claims from 3 to 6, comprising a pedal (1 1 ) used to make and break an electrical circuit connecting the liquid electrode (4) to the high voltage generator (5).

8. The device according to any of the claims from 3 to 7, comprising:

- an actuator (13) configured to deform one end of the glove (7) between a first configuration, where the opening (8) of the glove (7) is wide open to allow the hand to be inserted into it, and a second configuration, where the opening (8) of the glove (7) is tightly closed to prevent gas from escaping from the glove;

- a duct in communication with the space inside the glove (7) and connected to an extractor.

9. The device according to claim 1 or 2, wherein the first face of the dielectric layer (3) defines the inside surface of a sealed container (14) filled with the liquid electrode (4) and has at least one elastic portion.

10. A method for treating a three-dimensional surface with cold plasma generated using the "dielectric barrier discharge" technique, comprising the following steps:

- preparing an electrode (4) connected to a high-voltage generator (5); - preparing a layer (3) of deformable dielectric material having a first face which is coupled to the electrode (4);

- juxtaposing a second face of the dielectric layer (3) with the surface to be treated, defining a counter-electrode,

characterized in that the electrode (4) is made from a liquid or semi liquid material with low electrical resistivity and the dielectric layer (3) is made from a material which is impermeable to that liquid.

1 1 . The method according to claim 10, wherein the first face of the dielectric layer (3) defines an outside surface of a glove (7) which is partly immersed in the liquid electrode (4) and which has an opening (8) that is accessible from the outside of the liquid electrode (4), the juxtaposing step comprising inserting the surface to be treated into the glove (7).

12. The method according to claim 10, wherein the first face of the dielectric layer (3) defines the inside surface of a sealed container (14) filled with the liquid electrode (4) and has at least one elastic portion, the juxtaposing step comprising pressing the second face of the dielectric layer (3) against the surface to be treated to deform the dielectric layer (3) in such a way that it adapts to the shape of the surface to be treated.