Flat flexible support piece for a dielectrically impeded plasma treatment

In the case of a flat flexible support piece comprising an electrode arrangement, to which a high voltage can be supplied, for a dielectrically impeded plasma treatment of a surface to be treated, wherein the electrode arrangement has at least one flat electrode (3) and a dielectric layer (2) which has a support face for the surface to be treated and which is composed of flat flexible material and which electrically shields the at least one electrode (3) from the surface to be treated such that only a dielectrically impeded current flow between the at least one electrode (3) and the surface to be treated is possible when a plasma field is produced by the bias on the electrode (3) in a gas space between the electrode arrangement and the surface to be treated, simplified handling and increased safety are achieved in that the support piece has a high-voltage stage (14) for generating a high voltage, the output of said high-voltage stage being connected to the at least one electrode (3) by a connecting piece (17, 17′) on the support piece.

FIELD OF THE INVENTION

The invention relates to a planar flexible application piece having an electrode arrangement, which can be supplied with a high voltage, for a dielectric barrier plasma treatment of a surface to be treated, the electrode arrangement comprising at least one planar electrode and a dielectric layer of a planar flexible material having a bearing face for the surface to be treated, said dielectric layer electrically shielding the at least one electrode from the surface to be treated in such a way that only a dielectric barrier current can flow between the at least one electrode and the surface to be treated when a plasma field is formed in a gas space between the electrode arrangement and the surface to be treated by the high voltage of the electrode.

BACKGROUND

The treatment of surfaces, which also includes human skin, with a dielectric barrier plasma field is known. For example, DE 10 2009 060 627 B4 discloses a planar flexible application piece having the above features. The planar and flexible electrode, which is preferably fully enclosed by the dielectric in this case, is supplied in a suitable way via a high-voltage cable with a high voltage which is required for the formation of the dielectric barrier plasma field. The contacting of the electrode may be carried out at an electrode terminal which is fitted in a housing and protrudes from the dielectric layer. In an arrangement disclosed by EP 2 723 447 B1, the contacting of the electrode is carried out by means of a cutting contact which is pushed through the dielectric layer so as to contact the electrode through the dielectric. This cutting contact is arranged in a contact housing by which contacting of an operator with the high voltage is reliably prevented.

EP 2 946 641 B1 discloses, for an electrode arrangement especially described with a dielectric in the shape of a ball, that the high voltage is generated in the handle of a housing, in order then to be conducted to the electrode by means of a line routed in the housing. With the handle of the housing, the ball-shaped electrode arrangement can be moved over the surface to be treated, for example a skin surface, in such a way as to cover the surface.

SUMMARY

The object of the present invention is to make the delivery of the high voltage to an electrode of the electrode arrangement simpler and more reliable.

In order to achieve this object, according to the invention a planar flexible application piece of the type mentioned in the introduction is characterized in that the application piece comprises a high-voltage stage for generating a high voltage, the output of which is connected to the at least one electrode by a connecting piece on the application piece.

The application piece according to the invention therefore contains not only the electrode arrangement but also the high-voltage stage. This has the advantage that the output of the high-voltage stage can be connected on the shortest path to the at least one electrode of the electrode arrangement. This may be done by means of a correspondingly insulated connecting piece; in a particularly preferred embodiment, the connecting piece is contained as a conductive section inside the dielectric layer. Accordingly, the connecting piece carrying the high voltage may preferably be enclosed by the dielectric enclosing and insulating the at least one electrode, and therefore be insulated reliably against touching. In the application piece according to the invention, the problem of high-voltage delivery over a relatively long distance therefore does not arise. The short conductive section between the high-voltage stage and the at least one electrode of the electrode arrangement may comprise its own insulation, although it is preferably enclosed by the dielectric which also encloses the at least one electrode. To this end, the connecting piece may be a conductor track introduced into the dielectric layer. The conductor track may be arranged as a prefabricated component for connecting the high-voltage stage and the at least one electrode, and then be enclosed by the dielectric, preferably by the injection-molding method. It is, however, also possible to form the conductive section that constitutes the connecting piece inside the dielectric layer from an injection-molded plastic material having conductive additives. In this case, it is expedient to carry out three-stage injection molding, with which a lower level of the dielectric layer, then the conductive layer of the connecting piece, and subsequently the upper level of the dielectric layer is injected. With the production of the conductive section, at the same time the at least one electrode may likewise be produced from a plastic material having conductive additives, and preferably in the same injection-molding step as the connecting piece.

In one embodiment of the invention, the planar flexible application piece may be configured without terminals leading out, if it furthermore comprises batteries for a DC voltage supply and a control circuit for converting the DC voltage into AC voltage signals of a higher peak voltage. The AC voltage signals formed in this way may then be passed to the high-voltage stage. The batteries may likewise be embedded in the dielectric, so that the connecting lines between the batteries and the control circuit, and between the control circuit and the high-voltage stage, can be produced in the same way as the conductive section of the connecting piece. The batteries and parts of the control circuit, in particular a microprocessor chip, may suitably be introduced into the dielectric, in particular when the dielectric is formed by the injection-molding method. In the embodiment with batteries being used, the planar flexible application piece is independent of any voltage supply. The very economically producible batteries, control circuit and high-voltage stage make it possible to configure the planar flexible application piece as a disposable article, which is advantageous in particular for use as a wound dressing because any reconditioning outlay can be obviated. Optionally, the batteries may be made removable from the material of the dielectric, in order to be able to dispose of the batteries separately or to recycle them. The batteries may be conventional disposable batteries, but also rechargeable (accumulators).

In an intermediate stage, the planar flexible application piece comprises only terminals for an AC supply voltage from which the high-voltage stage then generates the required high voltage. In this case, disposal of the batteries is obviated and the connection of the AC voltage supply may be configured in conventional technology because the handling of a high voltage is obviated.

In one embodiment of the invention, an AC voltage passes to the input of the high-voltage stage. The high-voltage stage may generate therefrom AC voltage pulses which have a frequency of between 100 Hz and 100 MHz and are preferably configured as narrow needle pulses with rapidly decaying AC voltage oscillations. The high voltages used lie expediently between 1 kV and 100 kV.

In one embodiment of the invention, the electrode arrangement comprises at least two electrodes, which can be supplied in a phase-shifted manner with the AC high voltage. When AC voltage pulses are used, it may be expedient to deliver the AC voltage pulses in phase opposition to the at least two electrodes, so that a doubled voltage is formed between the electrodes. In this way, the efficiency of the plasma formation in relation to the surface to be treated, in particular the skin surface, can be improved even when the surface to be treated is used as a back electrode, which is for instance at ground potential. In the case of pulses in phase opposition, the ground potential is a zero potential which lies centrally between the two peak voltages of the pulses in phase opposition. This central potential occurs even when the surface, i.e. for example the human or animal body to be treated, is not separately placed at ground potential/earth potential.

The planar flexible application piece according to the present invention may, in one embodiment, be formed as a wound dressing comprising a wound-compatible material. The wound-compatible material may in this case be the material of the dielectric layer. It is, however, also possible to apply a wound-compatible material onto the application surface of the dielectric, which is intended for application on the surface to be treated.

In one simple and preferred embodiment of the invention, the dielectric is configured as an injection-molded part and encloses both the at least one electrode and the high-voltage part on all sides. If a control part and optionally batteries are also provided, these may also be enclosed by the dielectric, so that the dielectric functions as an encapsulation for all the electrical parts of the application piece.

DESCRIPTION

The exemplary embodiment represented inFIG. 1is represented inFIG. 1a) in a view from below, with parts inside the application piece, which are not visible during use, being represented. The exemplary embodiment is furthermore represented with the aid of a longitudinal section A-A inFIG. 1a) and a plurality of cross sections B-B (FIG. 1c)), C-C (FIG. 1d)), D-D (FIG. 1e)) and E-E (FIG. 1f).

The application piece represented has an essentially rectangular base shape, in which an edge1extends around. The edge1may be configured to be pressure-sensitively adhesive on its lower side, in order to be able to adhesively fasten the application piece on the skin of a body part, for example. The circumferential edge1may be connected integrally to a dielectric layer2, which is configured with a larger thickness than the circumferential edge1. A layer of conductive material as electrode3is embedded in the dielectric layer2, i.e. enclosed on all sides by the material of the dielectric layer2. In the exemplary embodiment represented, the electrode3likewise has a rectangular shape, although on all sides this does not extend as far as the dielectric layer2, so that the dielectric layer2protrudes with edge sections beyond the electrode3on every side. It is clear that the represented basic shape of the application piece may also be configured differently, for example polygonally, roundly, ovally or the like. In the region of the electrode3, the dielectric layer2is configured on its lower side in a grid structure4which consists of narrow intersecting webs5, so that in cross section approximately square, downwardly open chambers6are formed. Despite their small wall thickness, the webs5form a stable grid structure4, which acts as a spacer when the application piece is applied on a surface to be treated. In this way, in the gas space (air space) of the chambers6, a stable dielectric barrier plasma discharge caused by the electrode3can be formed, with which the treatment of the surface is carried out. The structural stability existing because of the grid structure4makes it possible to keep the width of the webs very small, so that the air space in the chambers6is optimally large. The width of the webs is, for example, less than ⅕ of the extent of the chambers6as measured perpendicularly to the webs.

It is clear to the person skilled in the art that the chambers6, which are formed inFIG. 1by webs5extending perpendicularly to one another, may also have different shapes, for example rhombic shapes, hexagonal shapes (honeycomb structure), etc. In order that the advantage of the stability of the grid structure4is achieved, it is expedient to provide at least four, in particular at least six, and more particularly eight chambers6successively in each direction of the dielectric layer2. For the case in which an elongate electrode arrangement consisting of dielectric layer2and electrode3is required, it is conceivable to also arrange a smaller number of chambers6next to one another in the width direction, if a larger number of chambers6is provided in the longitudinal direction. The number of chambers6on the lower side of the dielectric layer2is in conventional applications at least12, in particular at least20, and in many cases at least40. The exemplary embodiment represented inFIG. 1comprises thirteen chambers6in the longitudinal direction and eight chambers6in the width direction, which gives a total number of 104 chambers6.

In the embodiment represented inFIG. 1, the application piece does not have any terminals leading out, and is thus independently capable of generating a plasma field in the chambers6when the surface to be treated, on which the application piece is then applied, functions as a back electrode. The application piece therefore comprises a single electrode3, which must be supplied with a high voltage in order to generate a plasma field in the chambers6.

For supplying the electrode3, three batteries7, here in the form of button cells, are provided in the application piece. The batteries are located in a lower edge piece8of the dielectric layer2, which edge piece may be configured to be thickened in a bulging manner in order to receive the batteries, as can be seen in the sectional representations C-C and D-D (FIGS. 1d) ande)). The batteries7are connected to one another by conductor tracks9embedded in the dielectric layer2. The conductor tracks9extend over a lateral edge piece10of the dielectric layer as far as a microcontroller chip11. Together with an electronic signal shaper12, the microcontroller11forms a control apparatus13. The output of the control apparatus13, formed by the output of the signal shaper12, is connected to the input of a transformer stage14which is used to form a working high voltage of, for example, 15 kV from an input voltage of, for example, 250 V. The arrangement consisting of control apparatus13and transformer stage14is located in an upper edge piece15of the dielectric layer2.

As illustrated by the sectional representations ofFIGS. 1cto 1f, the upper edge section15is likewise configured to be thickened relative to the dielectric layer2in the region of the electrode3in order to receive the electronic components. The electrode3does not extend into the edge pieces8,10and13.

The microcontroller chip11, the signal shaper12and the transformer stage14are connected to one another by conductor tracks16embedded in the dielectric layer2, which are configured in the same way as the conductor tracks9.

The connection of the output of the transformer stage14to the electrode3takes place by means of a high-voltage conductor track17suitable for transferring a high voltage, said high-voltage conductor track being able to be formed as a single appendage of the electrode3.

The microcontroller chip11receives its supply voltage from the batteries7, which may be electrically connected in series in order to provide the summed cell voltages as a supply voltage of the microcontroller chip11. The microcontroller chip11controls the formation of AC voltage pulses in the signal shaper12, which are stepped up from the supply voltage of the batteries, of a few V, to an AC voltage with a peak voltage of about 250 V. This AC voltage is passed to the transformer stage14in order to form high-voltage pulses, for example by means of discharge paths (not represented), in which case the high-voltage pulses (with alternating polarity) may represent AC voltage trains with a rapidly decreasing amplitude because of a certain tuned circuit behavior. By means of the high-voltage pulses, the electrode3is brought alternately to a high positive and negative potential relative to the surface to be treated, which acts as a back electrode, so that the desired dielectric barrier plasma discharge can take place in the gas (in particular air) contained in the chambers6.

FIG. 1also shows that the dielectric layer2delimiting the chambers6upward is provided with through-openings18through which, for example, fluid may be aspirated from the surface before, during or after the plasma treatment, or as an alternative a treatment gas can be fed into the chambers6before or during the treatment.

In order to shield the electrode3with the dielectric layer2in the region of the through-opening, for each through-opening18the electrode3comprises a recess19which is larger than the through-opening18, so that the wall of the through-opening18is formed without interruption by the material of the dielectric layer2.

Even though each chamber is provided with a through-opening18in the exemplary embodiment represented, this does not mean that such a configuration is necessary. Aspiration of fluid may also be carried out through a much smaller number of through-openings18. This applies in particular when the webs5of the grid structure4allow—at least partially—fluid communication between the chambers6. In the exemplary embodiment represented, each chamber6is provided with a through-opening18. This makes it possible to form webs5with a constant height, so that the webs5form substantially closed chambers6when the application piece is applied on the surface to be treated. In the case of unevenly configured surfaces, this is also achieved in that both the material of the dielectric layer2and the material of the electrode3are flexible, so that the application piece can adapt to an uneven surface, for example a skin surface or wound surface.

The second embodiment, represented inFIG. 2, differs from the embodiment ofFIG. 1only in that the electrode3is formed by two partial electrodes3a,3b, which are configured to engage in one another in the manner of a comb. Between the partial electrodes3a,3b, there is an insulating strip configured in a meandering shape through the material of the dielectric layer, because there is no electrically conductive electrode layer in this region.FIG. 2illustrates that this configuration of the electrode3does not alter the rest of the construction of the application piece. In particular, the chambers6may be present both in the region of the partial electrodes3a,3band in the region of the insulating strip. Likewise, in this case as well the through-openings18are provided for each chamber6.

The partial electrode3aand3bare supplied by the transformer stage14′, in a manner which is as in-phase as possible, with high-voltage pulses of mutually reversed polarity. This gives rise to a plasma field between the partial electrodes3a,3brelative to the back electrodes formed by the surface, but also a voltage difference that is two times as great between the two partial electrodes3a,3b, so that the plasma formation by the electric field present between the partial electrodes3aand3bis improved further.

The transformer stage14′ is in this case provided with two transformer coils, which are poled oppositely to one another and thus respectively supply one of the two partial electrodes3a,3bwith the voltage pulses. Correspondingly, there is also respectively a high-voltage conductor track17between the transformer stage14′ and the partial electrodes3aand3b.

The exemplary embodiment represented inFIG. 3corresponds to the exemplary embodiment according toFIG. 1, with the difference that independent batteries7are not provided. Rather, in this exemplary embodiment the application piece is provided with terminals20leading out to which a DC voltage source21can be connected. The terminals20may in this case be located on an appendage of the application piece, and correspondingly contacted, or else formed by a connecting cable with which the connection to the DC voltage source21is established. The DC voltage source21replaces only the batteries7, so that the construction and the function of the application piece remain unchanged. Since batteries7do not have to be contained in the application piece, the lower edge piece8of the exemplary embodiment according toFIG. 1may be omitted.

The exemplary embodiment represented inFIG. 4is identical to the exemplary embodiment according to3, but concerns an application piece having two partial electrodes3a,3b, while the exemplary embodiment according toFIG. 3relates to a single electrode3. In this regard as well, the functions are the same as described with respect toFIGS. 1 and 2.

The fifth embodiment, according toFIG. 5, only still contains the transformer stage14on the application piece. In this embodiment as well, the application piece contains terminals20for connecting to an external voltage supply apparatus, which is formed here by an AC voltage supply22, from which the transformer stage14generates the suitable high-voltage pulses for the formation of a plasma between the electrode3and the surface to be treated.

According toFIG. 6, the connection of an AC voltage supply directly to a transformer stage14may also be used for an appendage piece having two partial electrodes3a, ab—as described above. In the embodiments according toFIGS. 5 and 6, the AC voltage supply and the signal shaping are carried out externally. The advantage nevertheless remains that high-voltage signals, which are critical in terms of safety technology, do not need to be transmitted onto the appendage piece since the high-voltage signals are only generated in the transformer stage14inside the appendage piece and are conducted on a short path, for example with the embedded high-voltage conductor tracks17, to the electrode3, or to the partial electrodes3a,3b. As described, the high-voltage conductor tracks17may be embedded in the dielectric layer, so that the insulation of the high-voltage lines17inside the dielectric layer2also takes place with the shielding of the electrode3, or of the partial electrodes3a,3b, with the same technology.

The seventh exemplary embodiment, represented inFIG. 7, corresponds to the first exemplary embodiment according toFIG. 1, although in this case the batteries7, the conductor tracks9,16, the microcontroller chip11, the signal shaper12and the transformer stage14are not enclosed by the material of the dielectric layer2but are mounted on the material of the dielectric layer2, as illustrated in particular byFIG. 7b. The conductor tracks9,16may in this case be applied directly onto the dielectric layer2, or printed onto a film which is in turn adhesively bonded onto the dielectric layer2. The electrical part is covered by a housing23, which is applied onto the dielectric layer and forms a downwardly open channel extending around in the shape of a strip on the edge of the dielectric layer2, which channel is closed underneath by the dielectric layer2. The housing23consists of an insulating material and, in order to obtain the flexibility required for adaptation of the application piece to uneven surfaces, may consist of an insulating, geometrically stable but pliable material, for example an elastomer.

The formation of an annularly closed housing23leads to versatile usability of the application piece, without creating a preferential direction. It is, however, also possible to configure the housing in the form of a strip only on one edge or—depending on requirements—with an L-shape or U-shape.

FIG. 7c) illustrates that the supply of the high voltage to the electrode3is carried out with a high-voltage conductor track17, which extends above the dielectric layer2and, through an opening of the dielectric layer2, contacts an appendage, routed in the dielectric layer2, of the electrode3with a projection17′. In this case as well, the high voltage is led only over a short distance and can be readily protected by the housing23against touching and sparking.

In all the exemplary embodiments, the dielectric layer2may preferably be produced by initially casting a lower level of the dielectric layer2, on which the electrode3is placed, whereupon an upper level of the dielectric layer is then cast, which is integrally connected to the lower level. As an alternative thereto, a lower level of the dielectric layer may be prefabricated, the electrode3then put in place, and finally an upper level of the dielectric layer2applied in prefabricated form. The two layers may then be adhesively bonded, or preferably welded using reflectors, to one another in an insulating manner. In yet another embodiment, the dielectric layer2may be produced integrally in one step by injection molding, the electrode3being placed in the injection mold.

In a similar way, the electrical components, such as batteries7, microcontroller chip11, signal shaper12and transformer stage14, may be integrated with the conductor tracks9,16and17into the dielectric layer. The thickening of the dielectric layer2in the lower edge piece8and in the upper edge piece15may, for example, be carried out during manufacture of the upper level of the dielectric layer2by the injection-molding method.

In all the embodiments represented, the application piece according to the invention may be configured and used as a disposable article. In the embodiments ofFIGS. 1, 2 and 7, the entire arrangement is disposed of, and in the other embodiments the connection to an external apparatus is merely released. In the case of connecting the application piece to a reduced-pressure source for the purpose of aspirating wound secretion, a material that absorbs the aspirated liquid may be arranged on the upper side of the dielectric layer, for example under an airtight film which assists the aspiration.

The application piece according to the invention is suitable, in particular, as a wound dressing which can remain on the wound for the entire duration of the healing of the wound, because the dielectric barrier plasma treatment can be initiated periodically for a required treatment time by the microcontroller chip11, with the result that the entire wound region can be repeatedly made germ-free so that accelerated healing of the wound is achieved. This is contributed to by a continuous increase, resulting from the plasma discharge, of the microcirculation in and around the wound region and/or in and around the intact skin.