Method for delivering ascorbic acid and / or one of its derivatives via iontophoresis

Abstract

The present invention relates to a cosmetic method for delivering ascorbic acid and / or one of its derivatives through the skin via iontophoresis, preferably bipolar iontophoresis, and / or electrostimulation, the method comprising the following steps: • providing a device comprising a main electrode, a counter-electrode and a power source electrically connected to the main electrode on the one hand and to the counter-electrode on the other hand, the main electrode and the counter-electrode being intended to be in direct or indirect contact with the skin and being separated from one another by a free space; • applying a cosmetic composition comprising ascorbic acid and / or one of its derivatives and one or more cosmetically acceptable additives to the main electrode and the counter-electrode but not to the free space; • applying the device to the skin such that the main electrode and the counter-electrode with the cosmetic formulation are in direct or indirect contact with the skin; • applying, over a certain time period, a direct current with an average current density of 0.03 mA / cm2 to 0.5 mA / cm2, preferably 0.1 mA / cm2 to 0.2 mA / cm2. The present invention also relates to an iontophoresis kit for implementing this method.

Description

[0001] Method for delivering ascorbic acid and / or one of its derivatives by iontophoresis

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to the field of skin treatment. More specifically, the present invention relates to a method for the cosmetic treatment of the skin, in particular by iontophoresis and / or electroporation and / or electrostimulation, preferably by bipolar iontophoresis.

[0004] STATE OF THE ART

[0005] Iontophoresis is an active technique that allows for improved passage of certain molecules into or through the skin using a low electrical current (< 1 mA). An iontophoretic device consists of a power source and at least two electrodes. One electrode is active, as the current entry point, the other is passive, as the current exit point. One electrode is then the anode, preferably connected to the positive pole, while the other is the cathode, preferably connected to the negative pole. The main mechanisms of iontophoresis are:

[0006] • Electro-migration or electro-repulsion: the electric current causes the ions to migrate according to their charge. A positively charged molecule in a formulation placed under the anode(+) will be repelled towards the skin and will be attracted by the electrode(-). On the contrary, a negatively charged molecule in a formulation placed under the cathode(-) will be repelled towards the skin and will be attracted by the electrode(+);

[0007] • Electro-osmosis or convective transport: allows the transport of molecules thanks to the movements of the solvent from the anode to the skin and from the skin to the cathode.

[0008] Many active molecules in skin care compositions are in ionic form, therefore iontophoresis can be an effective tool for the delivery of these active molecules.

[0009] Analysis of skin penetration profiles suggests insufficient penetration of ascorbic acid and its derivatives by simple topical application.

[0010] It is necessary to increase the penetration amount and release kinetics of ascorbic acid and to improve the release rate in the skin, compared to topical application. It has been surprisingly discovered that the area of ​​application of the cosmetic composition relative to the electrodes and the current value are crucial to improve the penetration of ascorbic acid and its derivatives into the skin.

[0011] SUMMARY OF THE INVENTION

[0012] A first subject of the invention relates to a non-therapeutic cosmetic process for delivering ascorbic acid and / or one of its derivatives through the skin by iontophoresis, preferably bipolar, and / or electrostimulation comprising the following steps:

[0013] • Provide a device comprising a main electrode, a counter-electrode and a power source electrically connected to the main electrode on the one hand and to the counter-electrode on the other hand, the main electrode and the counter-electrode being intended to be in direct or indirect contact with the skin and being separated from each other by a free space;

[0014] • Applying a cosmetic composition comprising ascorbic acid and / or one of its derivatives and one or more cosmetically acceptable additives to the main electrode and the counter-electrode but not to said free space;

[0015] • Apply said device to the skin so that the main electrode and the counter electrode with the cosmetic formulation are in direct or indirect contact with the skin;

[0016] • Apply a direct current with an average current density of 0.03 mA / cm over a certain time range 2at 0.5 mA / cm 2 , advantageously 0.03 mA / cm 2 at 0.3 mA / cm 2 preferably 0.1 mA / cm 2 at 0.2 mA / cm 2 and particularly advantageously substantially equal to 0.1 mA / cm 2

[0017] A second subject of the invention relates to an iontophoretic kit comprising:

[0018] • A cosmetic composition suitable for an iontophoretic process comprising ascorbic acid and / or one of its derivatives and one or more cosmetically acceptable additives, and

[0019] • An iontophoretic device for implementing the method according to the invention.

[0020] DESCRIPTION OF FIGURES

[0021] [Fig. 1]: Diagram of a drop-shaped iontophoresis device (power source not shown) [Fig. 2]: Diagram of a drop-shaped iontophoresis device according to one embodiment

[0022] [Fig. 3]: diagram of a circular iontophoresis device according to one embodiment

[0023] [Fig. 4]: diagram of the support layer of a drop-shaped iontophoresis device according to one embodiment

[0024] [Fig. 5]: diagram of the support layer of a circular iontophoresis device according to one embodiment

[0025] [Fig. 6]: diagram of the support layer of a triangular-shaped iontophoresis device according to one embodiment

[0026] [Fig. 7]: Diagram of the operation of a device, according to a sectional view, when it is applied to the skin of a user

[0027] [Fig. 8]: diagram summarizing the methods of applying the cosmetic composition to the electrodes

[0028] [Fig. 9]: evaluation of the penetration of the active ingredient according to the method of application of the composition (vs. passive 1)

[0029] [Fig. 10]: evaluation of the penetration of the active ingredient according to the method of application of the composition (vs. passive 2)

[0030] [Fig. 11]: Comparison of the penetration of the skin active ingredient between the method of applying the composition to the two electrodes and the sum of the two methods at one electrode

[0031] [Fig. 12]: Comparison of skin penetration of the active ingredient at different current densities

[0032] [Fig. 13]: Diagram of a full-face mask iontophoresis device

[0033] [Fig. 14]: Diagram of a partial mask iontophoresis device

[0034] [Fig. 15]: diagram illustrating the principle of ion migration according to the invention

[0035] DETAILED DESCRIPTION OF THE INVENTION

[0036] A first subject of the invention relates to a non-therapeutic cosmetic process for delivering ascorbic acid and / or one of its derivatives through the skin by iontophoresis, preferably bipolar, and / or electrostimulation comprising the following steps:

[0037] • Provide a device (0) comprising a main electrode (22), a counter-electrode (23) and a power source electrically connected to the main electrode (22) on the one hand and to the counter-electrode (23) on the other hand, the main electrode (22) and the counter-electrode (23) being intended to be in direct or indirect contact with the skin and being separated from each other by a free space (25);

[0038] • Applying a cosmetic composition comprising ascorbic acid and / or one of its derivatives and one or more cosmetically acceptable additives to the main electrode (22) and the counter-electrode (23) but not to said free space (25);

[0039] • Applying said device (0) to the skin so that the main electrode (22) and the counter electrode (23) with the cosmetic formulation are in direct or indirect contact with the skin;

[0040] • Apply a direct current with an average current density of 0.03 mA / cm over a certain time range 2 at 0.5 mA / cm 2 , preferably 0.1 mA / cm 2 at 0.2 mA / cm 2 .

[0041] The method according to the invention can be applied to any biological subject, in particular mammals, preferably human beings.

[0042] Ascorbic acid and derivatives

[0043] This method relates to the delivery of ascorbic acid and / or one of its derivatives. The ascorbic acid may be in the D or L form, preferably in the L form. Among its derivatives, mention may be made of salts of ascorbic acid such as sodium ascorbate, ose esters of ascorbic acid and salts of phosphorylated ascorbic acid.

[0044] The ose esters of ascorbic acid which can be used in the context of the present invention are in particular the glycosylated, mannosylated and fructosylated derivatives of ascorbic acid, more particularly 2-OaD-Glucopyranosyl of L-ascorbate (INCI name: ascorbyl glucoside).

[0045] The phosphorylated ascorbic acid salts which can be used in the context of the present invention are the salts of alkali or alkaline-earth metals such as magnesium or sodium ascorbylphosphate.

[0046] Preferably, the ascorbic acid and / or one of its derivatives are chosen from ascorbic acid, magnesium ascorbylphosphate, sodium ascorbylphosphate, ascorbyl glucoside, 3-O-ethyl ascorbic acid, ascorbyl palmitate and mixtures thereof, preferably ascorbyl glucoside. With reference to Figure 1, a bipolar iontophoresis device 0 and a set of electrodes 22 and 23 are illustrated schematically.

[0047] The device 0 is intended to be applied to the user's skin, preferably to the face. However, the device 1 could be applied to any other skin part of the user's body. The invention provides different forms of device which are remarkably well suited for particular areas of the face which are often the subject of a desire for treatment by users.

[0048] With reference to Figures 1, 2, 3 and 6, the device may therefore have different shapes depending on the area to which it is designed to be applied. For example, a device 0 or 1a intended to be applied to the temple may have a general drop shape. Thus, the contours of the device are rounded and a first portion of the device, when viewed from above, is wider than a second portion of the device. A device 1b intended to be applied to the cheekbone may have a circular shape. Thus, when viewed from above the device forms a disc. A device intended to be applied to the forehead may have a triangular shape, Figure 5 illustrating a layer 2c of this device.Thus, thanks to the different shapes proposed by the invention, each area of ​​the face traditionally treated by care (cheekbone, forehead, temple) has a device particularly well adapted to the shape of the area in question, which makes it possible to increase the comfort of use, the ergonomics and the effectiveness of the treatment. However, other shapes could be imagined, without departing from the scope of the invention, which would be adapted to other areas of the face or other skin areas of the body such as the tops of the hands, the décolleté, etc.

[0049] Whatever the embodiment of the device, the device 0 notably comprises a power source (not illustrated), such as a battery, a rechargeable battery or a current generator which is activated by the application of the cosmetic composition, a first electrode 22, a counter-electrode 23. The device may also comprise other electrodes and other elements (such as a light-emitting diode for example) without departing from the scope of the invention.

[0050] A suitable power source is any power source capable of generating electrical current to power the various other circuits and devices. In some embodiments, a battery, preferably a rechargeable battery, is used as the power source. In some embodiments, the iontophoresis device is plugged into a wall outlet. In some embodiments, the power source produces direct current.

[0051] The electrodes 22, 23 are intended to be in direct or indirect contact with the skin. By indirect contact, it is meant that an element is arranged between the electrode 22, 23 and the skin such as a cosmetic composition, an absorbent layer and / or a fabric, etc. It is understood that when an element is arranged between the electrodes and the skin, in particular an absorbent layer and / or a fabric, the step of applying the cosmetic composition to the electrodes corresponds to the application of the cosmetic composition to this intermediate element.

[0052] In operation, the cosmetic composition is thus absorbed by the skin at the main electrode 22, the shape of which can then advantageously be chosen to correspond as precisely as possible with the area to be treated. Thus, the main electrode 22 of the device can advantageously have the same shape as the general shape of the device 0. This makes it possible to position the main electrode 22 as close and as precisely as possible opposite the specific area to be treated (cheekbone, temple, forehead, etc.). However, unexpectedly, it is also important to also apply the cosmetic composition at the counter-electrode in order to optimize the penetration of the cosmetic composition comprising ascorbic acid and / or one of its derivatives.

[0053] The main electrode 22 may be a cathode or an anode and, correspondingly and inversely, the counter electrode 23 may be an anode or a cathode. Preferably, the main electrode 22 will be adapted to be a cathode.

[0054] More specifically, the cosmetic composition may comprise molecules that are positively or negatively charged at a given pH. If the main electrode 22 has the same polarity as the polarity of the molecules, the molecules are repelled by the main electrode 22 and thus pushed towards the user's skin. For example, ascorbic acid molecules are negatively charged for a pH between 5 and 7. A device 0 aimed at improving the absorption by the skin of ascorbic acid molecules present in the cosmetic composition will therefore preferably have a main electrode 22 forming an anode. The main electrode 22 preferably comprises carbon, advantageously in the form of a plurality of carbon dots, for example arranged under the main metal constituting the main electrode.This makes it possible to give the user a visual indication of the main electrode 22 (or active electrode as explained previously) to help him position the latter correctly on the area of ​​the skin that he wishes to treat, without degrading the electrical conductivity of the main electrode 22.

[0055] The counter-electrode 23 has a polarity opposite to that of the main electrode 22. The counter-electrode 23 is therefore a cathode if the main electrode 22 is an anode and the counter-electrode 23 is therefore an anode if the main electrode 22 is a cathode.

[0056] The main electrode 22 and the counter electrode 23 are made from conductive materials, typically metals.

[0057] The main electrode 22 and the counter electrode 23 preferably comprise silver and / or silver chloride. More preferably, the main electrode 22 and the counter electrode 23 are made of silver and / or silver chloride. Silver and silver chloride have the advantage of being hypoallergenic and interacting well with the skin. In addition, silver and silver chloride have the advantage of being good conductors of electricity. Silver chloride is less prone to oxidation than silver, so that combined with silver, it helps to limit oxidation and therefore improve the durability of the electrodes 22, 23.

[0058] Preferably, the main electrode 22 and the counter electrode 23 are made of silver and silver chloride. More specifically, the main electrode 22 and the counter electrode 23 are each composed of 55% silver and 45% silver chloride.

[0059] Alternatively, the main electrode 22 and / or the counter electrode 23 are made of carbon. Carbon is conductive and not very oxidizable.

[0060] The device 0 may further comprise an impregnation layer comprising at least one impregnation film, the impregnation layer covering at least the main electrode 22 and the counter-electrode 23.

[0061] Preferably, in operation, it is preferable that cosmetic composition is also present between each of the electrodes 22, 23 and the user's skin to facilitate the circulation of the electric current between the device 1 and the skin. This also makes it possible to limit the risk of reddening of the skin upon contact with the electrodes 22, 23 and to increase the comfort of use. In addition, this impregnation layer also makes it possible to act as a reservoir of cosmetic composition, more precisely of ascorbic acid and / or one of its derivatives, for a certain period of time. The impregnation film is made from at least one porous material, that is to say a material which absorbs the cosmetic composition.

[0062] Preferably, the impregnation film is made from a non-woven fabric, for example non-woven cotton. A non-woven fabric has the advantage of being absorbent and is generally hypoallergenic so that it can be brought into contact with the skin of a user without risk of skin reaction. In addition, a non-woven fabric has the advantage of being very flexible and therefore does not limit the flexibility of the device 0.

[0063] The thickness of the impregnation layer will be chosen according to the desired absorption capacity of the impregnation layer, typically greater than or equal to 100 pm, preferably greater than or equal to 800 pm, and less than or equal to 2 mm.

[0064] The impregnation film may be made from materials adapted to the viscosity of the cosmetic composition. For example, if the cosmetic composition is very low in viscosity and therefore very liquid (as would be the case, for example, with physiological serum or saline solution), it would be desirable for the impregnation film to be made from a highly absorbent material to prevent, when the cosmetic composition is applied to the device 0, the cosmetic composition from spreading (by capillarity) in an undesired manner in the device 0 (for example, keeping the free space 25 free of cosmetic composition) or from flowing out of the device 0 (for example, to the ground).Conversely, if the cosmetic composition is very viscous (as would be the case, for example, with a cosmetic cream or gel), it would be desirable for the impregnation film to be made of a low-absorbency material to allow the impregnation film to soak up sufficiently.

[0065] The impregnation layer may comprise a single impregnation film which covers the assembly comprising the main electrode 22 and the counter-electrode 23. In this case, the impregnation layer is said to be monolithic. For example, this embodiment, which is particularly simple and easy to implement during the manufacture of the device 0, is well suited in the case where the cosmetic composition has a high viscosity (it is therefore pasty, for example in the form of a cosmetic cream). Indeed, in this case, when the cosmetic composition is applied opposite the electrodes, the cosmetic composition remains substantially in this area and does not spread in an undesirable manner onto other undesirable areas of the impregnation layer, in particular to avoid the formation of a “bridge” of cosmetic composition between the two electrodes 22 and 23, that is to say to avoid a continuity of cosmetic composition between the two electrodes 22 and 23.

[0066] In this case of a monolithic impregnation layer, the impregnation layer may comprise at least one capillary action limiting device, such as a groove, a throat or even a slot. Such a device makes it possible to cut capillary paths within the impregnation layer and thus to locally limit the diffusion of the cosmetic composition within the impregnation layer by capillarity. Advantageously, the impregnation layer comprises two capillary action limiting devices, arranged on either side of the free zone 25.

[0067] However, it is perfectly conceivable, without departing from the scope of the invention, to provide a device without an activation layer. Such a device would then be suitable for the use of a cosmetic composition in the form of a gel or cream of high viscosity.

[0068] Other devices according to the invention are illustrated in Figures 13 and 14.

[0069] The device 10 of Figure 13 illustrates, for example, a bipolar iontophoresis device particularly well suited to covering and treating the entire face of a user.

[0070] More specifically, the device 10 comprises a substrate 11 comprising a first opening 12 and a second opening 13 intended to correspond with the user's eyes, a cutout 15 intended to accommodate the user's nose, a third opening 14 intended to accommodate the user's mouth. The substrate 11 also comprises different notches 16 allowing the device 10 to be adjusted to the face. The device 10 comprises at least one main electrode 22 (advantageously forming a cathode) and at least one counter electrode 23 which can form a current-generating galvanic couple, or be connected to a set of current-generating galvanic couples (not shown) or even to an external power supply (not shown). The substrate 11 is further provided with markings 17. The markings 17 have the form of linked dotted lines.

[0071] These markers 17 can be used by a user to correctly position the device 10 on the face.

[0072] The device 30 of Figure 14 illustrates for example a bipolar iontophoresis device particularly well suited to covering and treating the upper part of the face (forehead and around the eyes). The device 30 then comprises a substrate 31 comprising openings 32 and 33 intended to correspond with the user's eyes, at least one main electrode 22 (advantageously forming a cathode) and at least one counter electrode 23 which can form a current-generating galvanic couple, or be connected to a set of current-generating galvanic couples (not illustrated) or even to an external power supply (not shown).

[0073] Whatever the device, the main electrode 22 and counter electrode 23 can be powered by a battery or cell type current generator, the latter being able to be integrated or remote from the device.

[0074] As mentioned, the iontophoresis device is a bipolar device, as it has at least two electrodes of opposite polarities. Thus, unlike a galvanic iontophoresis device, it is possible to precisely control the area of ​​application of the current as well as the path taken by the current through the human body, by limiting the latter between the two electrodes.

[0075] Device activation

[0076] According to a preferred embodiment, the method according to the invention uses a device 1, 10, 30 which is adapted to control the area of ​​application of the cosmetic composition and which is adapted to be activated, i.e. placed in operating conditions, by an activation product which is electrically conductive. In other words, the generation of electric currents is triggered by the application of a product to at least certain areas of the device 1, 10, 30. The device 1, 10, 30 is therefore inactive in the absence of the activation product, and only becomes active when the activation product is in contact with at least one predefined area, as will be detailed later. This makes it possible to control the moment of activation of the product, and in particular to match this moment to the actual use of the device 1, 10, 30 by the user.Thus, during the storage (or transport) phase of the device 1, 10, 30, the latter is not activated, thus preserving its lifespan, and in particular the lifespan of the current generator. According to this preferred embodiment, the activation product is the cosmetic composition comprising ascorbic acid and / or one of its derivatives.

[0077] Referring to Figures 4 to 6, the device 1 comprises a support layer 2. By support layer is meant any layer serving as a support for other layers, in this case the impregnation and stencil layers. Figure 4 illustrates the support layer 2a of a drop-shaped device 1a. Figure 5 illustrates the support layer 2b of a circular-shaped device 1b. Figure 6 illustrates the support layer 2c of a triangular-shaped device.

[0078] With reference to Figure 4, the support layer 2 comprises at least one support film 21. The support film 21, and consequently, the device 1, is sufficiently flexible to be able to adapt to the shapes and reliefs of the skin of the area to be treated, and in particular to the cheekbones, temple, and forehead, as explained previously. The support film 21 is preferably insulating, that is to say that it does not allow current to pass. This makes it possible to avoid any risk of short circuit within the device, by preventing the current from circulating in the support film 21.

[0079] The support film 21 is for example made of a flexible plastic such as polyurethane (PU) or polyethylene terephthalate (PET). Preferably, the support film 21 has a thickness greater than or equal to 20 μm, preferably greater than or equal to 40 μm, and less than or equal to 90 μm, for example substantially equal to 50 μm or 80 μm. Indeed, such thicknesses allow the support film 21, and therefore the device 1, to conform well to the area of ​​skin on which it is intended to be placed.

[0080] The device 1 may comprise a plurality of support films 21 assembled together, for example by gluing. On the contrary, the support film may be monolithic, that is to say formed from a single film.

[0081] The support layer 2 comprises at least one main electrode 22, at least one counter-electrode 23 and at least one current generator 24. The current generator 24 is electrically connected to the main electrode 22 on the one hand and to the counter-electrode 23 on the other hand, so as to create an electrical potential differential between the latter.

[0082] The electrodes 22, 23 are intended to be applied opposite the user's skin and are adapted to allow the circulation of an electric current in the user's skin, when the device 1 is placed in contact with the user's skin. Indeed, the user's skin behaves as a current consumer, in particular as a resistor. The skin of a mammal, in particular human skin, typically behaves as a 10 kΩ resistor. For this purpose, the main electrode 22 and / or the counter electrode 23 is formed at least from one main metal, a good electrical conductor.

[0083] The device 1 is in a so-called “operating” state when it is applied to the skin of a user and when the current generator 24 is activated so as to generate an electric current. The expression “in operation” will subsequently be used to designate a situation in which the device 1 is in operation, that is to say that it generates a potential differential between the electrodes, then an electric current when the device is applied to the skin.

[0084] In operation, the electric current generated by the current generator 24 flows between the electrodes 22, 23 and into the user's skin. As illustrated in FIG. 7, the electric current flows via the current generator 24 to the main electrode 22, then enters the user's skin to reach the counter electrode 23. The current can also flow in a direction opposite to that illustrated.

[0085] Advantageously, the main electrode 22 and the counter-electrode 23 are printed on the support film 21 using conductive inks, and preferably metallic inks. In particular, the main electrode 22 and the counter-electrode 23 are preferably printed on the support film 21 by screen printing.

[0086] The current generator 24 comprises at least one galvanic couple 240. The galvanic couple 240 is formed of a first conductive pole 241 forming a cathode and a second conductive pole 242 forming an anode separated from each other by a free space 243. The free space 243 is preferably insulating, that is to say that it does not allow the electric current to pass through. This can for example be made possible by the fact that the support film 21 is insulating and that the free space 243 consists of an area of ​​the support film 21 on which no material is printed.

[0087] Alternatively, an insulating material could be disposed on the support film 21 at the free space 243.

[0088] Preferably, the first conductive pole of a galvanic couple and the second conductive pole of a galvanic couple are separated by a distance of between 0.5 mm and 5 mm, preferably between 1 mm and 3 mm, for example equal to 2 mm. In other words, the free space 243 has a length of between 0.5 mm and 5 mm, preferably between 1 mm and 3 mm, for example equal to 2 mm.

[0089] The free space 243 is intended to be filled, at the time of activation (of putting into operation) of the device 1, by an electrically conductive activation product to connect together the first conductive pole 241 and the second conductive pole 242 of the same galvanic couple 240.

[0090] The first conductive pole 241 and the second conductive pole 242 of the galvanic couple 240 are adapted to, when connected by the activation product, allow the circulation of electrons between them. The electrons are generated by the difference between the standard electrical redox potentials of the first conductive pole 241 and the second conductive pole 242.

[0091] A galvanic couple 240 is thus adapted to generate an electric current when the first conductive pole 241 and the second conductive pole 242 are connected so as to allow an oxidation-reduction reaction between said poles. An electrochemical cell is formed.

[0092] More specifically, when the first conductive pole 241 and the second conductive pole 242 of the galvanic couple 240 are connected by the activation product, upon contact with the activation product, atoms constituting the second conductive pole 242 (forming an anode) oxidize and electrons are released. The electrons then flow via the activation product to the second conductive pole 242. As illustrated in FIG. 7, the activation product PÀ between the first conductive pole 241 and the second conductive pole 242 allows the flow of electrons and the generation of an electrical circuit.

[0093] Thus, in operation, the device 1 is traversed by an electric current without requiring an external battery or any other source of electrical power external to the device 1. This results in a remarkably limited size of the device 1, and remarkable freedom of use (no need for a power outlet, external battery, etc.).

[0094] The constituent materials of the first conductive pole 241 and the second conductive pole 242 advantageously comprise conductive materials, typically metals.

[0095] The first conductive pole 241 (forming the cathode) advantageously comprises silver and / or silver chloride. Preferably, the first conductive pole 241 is made of silver and / or silver chloride. The second conductive pole 242 (forming the anode) advantageously comprises zinc. Preferably, the second conductive pole 242 is made of zinc. In this case, the zinc is the reducing agent of the oxidation-reduction chemical reaction and the second conductive pole 242 (the zinc ink in this case) will be consumed during use of the device 1.

[0096] Thus, advantageously, when the first conductive pole 241 and the second conductive pole 242 are connected by an activation product, the zinc atoms are oxidized and therefore release electrons according to the following reaction: Zn -> Zn2+ + 2e-.

[0097] The electrons will flow from the first conductive pole 241 to the second conductive pole 242. This is made possible by the fact that the standard electrical redox potentials of zinc and silver are different. In this case, the theoretical standard electrical potential of zinc is -0.76 V and that of silver is +0.80 V. Thus, each galvanic couple 240 formed of zinc and silver theoretically makes it possible to produce a 1.56 V battery.

[0098] Galvanic couples 240 may include other materials. For example, these pairs can be formed from: zinc-copper, zinc-copper / copper halide, zinc-copper / copper oxide, magnesium-copper, magnesium-copper / copper halide, zinc-silver, zinc-silver-silver oxide, zinc-silver-silver halide, zinc-silver-silver chloride, zinc-silver-silver bromide, zinc-silver-silver iodide, zinc-silver-silver fluoride, zinc-gold, magnesium-gold, aluminum-gold, magnesium-silver, magnesium-silver-silver oxide, magnesium-silver-silver halide, magnesium-silver-silver chloride, magnesium-silver-silver bromide, magnesium-silver-silver iodide, magnesium-silver-silver fluoride, magnesium-gold, aluminum-copper, aluminum-silver, aluminum-silver-silver oxide, aluminum-silver / silver halide, aluminum-silver / silver chloride, aluminum-silver / silver bromide, silver / silver aluminum iodide, silver / silver aluminum fluoride,copper-silver / silver halide, copper-silver / silver chloride, copper-silver / silver bromide, copper-silver / silver iodide, copper-silver / silver fluoride, iron-copper, iron-copper / copper oxide, iron-copper, iron-copper / copper oxide, iron-copper / copper halide, iron-silver, iron-silver / silver oxide, iron-silver / silver halide, iron-silver / silver chloride, iron-silver / silver bromide, iron-silver / silver iodide, iron-silver / silver fluoride, iron-gold, iron-carbon conductor, zinc-carbon conductor, copper-carbon conductor, magnesium-carbon and aluminum-carbon.,

[0099] The galvanic couples 240 and the couple comprising the main electrode 22 and the counter electrode 23 may also comprise alloys.

[0100] As explained above, the current generator 24 is electrically connected to the main electrode 22 on the one hand and to the counter electrode 23 on the other hand. More precisely, the main electrode 22 is electrically connected to a first conductive pole 241 of a galvanic couple 240 or to a second conductive pole 242 of a galvanic couple 240.

[0101] Depending on the nature of the main electrode 22 (anode or cathode), the main electrode 22 is electrically connected to one or the other of a first conductive pole 241 of a galvanic couple 240 and a second conductive pole 242 of a galvanic couple 240.

[0102] For example, if the main electrode 22 is an anode, it will be connected to a second conductive pole 242 since the latter forms an anode. Generally, each of the main electrode 22 and counter electrode 23 is of the same polarity as the first or second conductive pole 241, 242.

[0103] The main electrode 22 and the counter-electrode 23 can be connected to a conductive pole 241, 242 of the same galvanic couple 240 or of different galvanic couples 240. In the case where the current generator 24 comprises a single galvanic couple 240, the main electrode 22 and the counter-electrode 23 are connected to a conductive pole 241, 242 of this same galvanic couple 240.

[0104] One of the electrodes 22, 23 is electrically connected to a first conductive pole 241 by a first connector 244. The other of the electrodes 22, 23 is electrically connected to a second conductive pole by a last connector 245.

[0105] In other words, the first conductive pole 241 connected to an electrode 22, 23 is connected to the electrode 22, 23 via the first connector 244. The second conductive pole 242 connected to an electrode 22, 23 is connected to the electrode 22, 23 via the last connector 245.

[0106] The main electrode 22 and the counter-electrode 23 can be connected to a conductive pole 241, 242 via connectors 244, 245 advantageously comprising carbon, and preferably made of carbon. A connector 244, 245 comprising carbon, referred to hereinafter as a carbon connector 244, 245, allows the circulation of an electric current.

[0107] A carbon connector 244, 245 is advantageously a carbon strip. A carbon connector 244, 245 preferably has a length of less than 5 mm and greater than 1 mm and a width of the order of 2 mm. The length of a carbon connector 244, 245 is preferably less than 5 mm to allow good current conductivity, a carbon connector that is too long having significant resistance. In the case where a connector is required over a longer distance, in particular greater than 5 mm, it will be preferable to use another better conductive material, preferably the material used for the main electrode 22 or the counter-electrode 23.

[0108] Preferably, a connector 244, 245 is printed on the support film 21 using a conductive ink comprising carbon, preferably by screen printing. A carbon connector 244, 245 comprises carbon but may additionally comprise other materials, preferably conductive materials.

[0109] The main electrode 22 and the counter electrode 23 may be connected to a conductive pole 241, 242 via connectors 244, 245 comprising other electrically conductive materials. For example, a connector 244, 245 may comprise the same material as a material included in the main electrode 22 and / or the counter electrode 23.

[0110] Alternatively, the main electrode 22 and the counter electrode 23 may be connected to a conductive pole 241, 242 by direct contact between an electrode 22, 23 and a conductive pole 241, 242.

[0111] According to a non-illustrated embodiment, the first connector 244 comprises a material identical to a material included in the electrode 22, 23. Preferably, the first conductive pole 241 and the electrode 22, 23 to which the first conductive pole 241 is connected comprise silver and / or silver chloride and the first connector 244 comprises silver and / or silver chloride. Also preferably, the last connector 245 is made of carbon.

[0112] According to an embodiment illustrated in Figure 4, the counter electrode 23 is connected to the first conductive pole 241, the counter electrode 23 and the first conductive pole 241 are made of silver and / or silver chloride and the first connector 244 which connects the counter electrode 23 and the first conductive pole 241 is made of silver and / or silver chloride. Since the counter electrode 23 and the first conductive pole 241 are made of the same material, they can be continuously connected by a first connector 244 of the same material. The printing of the counter electrode 23, the first conductive pole 241 and first connector 244 on the support film 21 is thus facilitated and does not require a different material for the first connector 244.

[0113] Furthermore, in the embodiment illustrated in Figure 4, the main electrode 22 is connected to the second conductive pole 242, the electrode 22 is made of silver and / or silver chloride, the second conductive pole 242 is made of zinc and the last connector 245 which connects the electrode 22 and the second conductive pole 242 is made of carbon.

[0114] Alternatively, the electrode 22 could be in direct contact with the second conductive pole 242 and there would be no additional connector.

[0115] Advantageously, the current generator 24 comprises a plurality of galvanic couples 240. It is then understood that the main electrode 22 is connected to a conductive pole 241, 242 of a galvanic couple 240a different from the galvanic couple 240d of which a conductive pole 241, 242 is connected to the counter-electrode 23. More precisely, a conductive pole 241, 242 of a first galvanic couple 240a is electrically connected to the main electrode 22 and a conductive pole 241, 242 of a last galvanic couple 240d is electrically connected to the counter-electrode 23.

[0116] The current generator 24 comprises a plurality of galvanic couples 240 connected in series. The galvanic couples 240 are thus adjacent two by two and are electrically connected two by two. This makes it possible to make a series connection of said plurality of galvanic couples 240, and therefore to increase the voltage potential, as will be detailed later.

[0117] Preferably, two adjacent galvanic couples 240 are separated by a distance equal to the distance which separates the two conductive poles 241, 242 of the same galvanic couple 240.

[0118] More precisely, two adjacent galvanic couples 240b, 240c are connected by connecting the second conductive pole 242b of one galvanic couple 240b and the first conductive pole 241c of the other galvanic couple 240c.

[0119] Advantageously, two adjacent galvanic couples 240 are electrically connected via a couple connector 246 advantageously comprising carbon. Preferably, the couple connector 246 is made of carbon. The couple connectors 246 make it possible to circulate an electric current from one galvanic couple 240 to another adjacent galvanic couple 240. Alternatively, the couple connector 246 may comprise other materials, such as electrically conductive metals. However, as illustrated in the various figures 2 to 7, it will be preferred to use carbon couple connectors 246 for its low cost, its ease of implementation and its harmlessness to the skin.

[0120] Preferably, with reference to Figures 4 and 7, the torque connector 246 extends below at least one conductive pole 241, 242 that it connects. In other words, the at least one conductive pole 241, 242 partially covers the torque connector 246.

[0121] More preferably, the couple connector 246 comprises a portion extending below at least 80% of the surface of a conductive pole 241, 242. Advantageously, the couple connector 246 comprises a portion extending below at least 80% of the surface of a second conductive pole 242. This makes it possible to improve the electrical conductivity between two adjacent galvanic couples 240. Advantageously, each couple connector 246 has, in top view, a p-shape (or symmetrically q-shape), that is to say that it has a solid, substantially square zone and a tail (or thin zone), the solid zone extending below the surface of a second conductive pole 242 while the tail is not covered. Such an arrangement makes it possible to optimize the passage of current between two adjacent galvanic couples 240 without impacting the redox reaction, or even by optimizing it.

[0122] Indeed, in the case, for example, of a couple connector 246 made of carbon and a second conductive pole 242 made of zinc, the conductivity is improved because carbon is more conductive than zinc. It has been measured that the conductivity could be multiplied by two when the couple connector 246 has a solid area under a conductive pole 241, 242.

[0123] According to one embodiment, the solid area of ​​the torque connector 246 corresponds to 100% of the surface of a second conductive pole 242. In the embodiment illustrated in FIG. 4 for example, the surface of a second conductive pole 242 is greater than the solid area of ​​the torque connector 246, that is to say that the second conductive pole 242 (in this case zinc) covers the torque connector 246 (in this case carbon) and protrudes from said torque connector 246. This makes it possible to ensure that, despite manufacturing tolerances, the second conductive pole 242 (in this case zinc) will completely cover the torque connector 246 (in this case carbon), in particular in order to guarantee a good aesthetic appearance of the device 1.

[0124] Alternatively, according to an embodiment not illustrated, two adjacent galvanic couples 240 are electrically connected by direct contact between the second conductive pole 242 of a galvanic couple 240 and the first conductive pole 241 of an adjacent galvanic couple 240. This makes it possible to achieve the series connection of said plurality of galvanic couples 240, without having to use another material.

[0125] Arranging a plurality of galvanic couples 240 in series makes it possible to generate, when the device 1 is in operation, a voltage (measured between the main electrode 22 and the counter-electrode 23) higher than the voltage generated by a single galvanic couple 240. Indeed, the voltages generated by each galvanic couple 240 of a series of galvanic couples 240 are cumulative. For example, theoretically, a zinc-silver galvanic couple 240 generates a voltage of 1.56 V. Consequently, theoretically, a current generator 24 comprising two galvanic couples 240 will generate a voltage of 3.12 V (1.56 V multiplied by 2) and a current generator 24 comprising three galvanic couples 240 will generate a voltage of 4.68 V (1.56 V multiplied by 3). Empirically, it has been measured that a 24 current generator comprising a 240 zinc-silver galvanic couple generates a voltage of 1.1 V.Thus, empirically, a current generator 24 comprising two galvanic couples 240 generates a voltage of 2.2 V (1.1 V multiplied by 2) and a current generator 24 comprising three galvanic couples 240 generates a voltage of 3.3 V (1.1 V multiplied by 3). The current generator 240 of the support layer 2 illustrated in FIG. 4 comprises five galvanic couples 240. Empirically, this current generator 24 generates a voltage of 5.5 V (1.1 multiplied by 5).

[0126] Consequently, in operation, the intensity of the electric current generated by the plurality of galvanic couples 240 in series is greater than the electric current generated by a single galvanic couple 240. Indeed, the resistance of the skin (which will consume the current) remaining identical, by increasing the voltage compared to the devices of the prior art, thanks to the series connection of said plurality of galvanic couples 240, the current (principle of Ohm's law) which will circulate in the skin is necessarily increased, when the device 1 of the invention is activated and placed on the skin. It is recalled that the skin behaves on average like a resistance of 10 kO (10,000 O). Thus, theoretically, a current generator 24 comprising a single galvanic couple 240 will generate a current of 110 pA (1.1 V / 10,000 O). Similarly, a 24 current generator comprising five 240 galvanic couples will generate a current of 550 pA (5.5 V / 10,000 O).Preferably, a current generator comprising three 240 galvanic couples can be chosen which will generate a current of 330pA (3.3 V / 10,000 O).

[0127] The performance of the current generator 24 is thus improved. Thus, more current flows into the user's skin, which will increase the treatment by iontophoresis and / or electrostimulation and / or electroporation.

[0128] Advantageously, the current generator 24 comprises at least three galvanic couples 240. Preferably, the current generator 24 comprises at least four galvanic couples 240 as in the examples illustrated in figures 4 to 6.

[0129] According to the embodiment illustrated in Figure 4, the current generator 24 comprises five galvanic couples 240. According to a certain embodiment not illustrated, the current generator may comprise at least two current generation assemblies each comprising a plurality of galvanic couples connected in series and the two current generation assemblies are connected in parallel. This makes it possible to accumulate the intensities of the electric currents generated by each current generation assembly. Thus, the intensity of the electric current generated by the current generator is increased.

[0130] Preferably, the elements printed on the support film 21 (electrodes 22, 23, current generator 24 and connectors 244, 245, 246) have a thickness of between 10 μm and 20 μm. The support film 21 has, as already mentioned, a thickness of between 20 μm and 90 μm, or 40 μm and 90 μm. Consequently, the support layer 2 preferably has a thickness of between 30 μm and 110 μm, or between 50 μm and 110 μm. The support layer 2 thus offers a remarkable compromise between electrical conductivity, flexibility, and duration of use.

[0131] The device 1 further comprises an impregnation layer 4 comprising at least one impregnation film 41. The impregnation layer 4 covers at least the main electrode 22, the counter-electrode 23 and the current generator 24.

[0132] Indeed, to operate the device 1, it is desired that the activation product be impregnated at the level of zones 42 of the impregnation layer 4, called “activation zones 42”.

[0133] First of all, it is necessary to activate the current generator 24 and therefore its galvanic couples 240. To do this, the conductive poles 241, 242 of each galvanic couple 240 must be connected together so that an oxidation-reduction reaction takes place, as explained above. This can be implemented by the presence of the activation product at the free spaces 243 between the conductive poles 241, 242 of each galvanic couple 240. Thus, it is desired that activation product be placed at the free spaces 243 and that activation product remain during a certain operating time of the device 1 at the free spaces 243. The impregnation layer 4 at the current generator 24 plays in particular the role of a reservoir of activation product and thus allows the activation of the galvanic couples 240 of the current generator 24 for a certain period of time.Thus, current is generated for a certain period of time, preferably for the time necessary for the treatment of the area of ​​the face to be treated. First activation zones 42a therefore correspond to the zones of the impregnation layer 4 arranged at the level of the free spaces 243. By “at the level”, it is understood that first activation zones 42a therefore correspond to the zones of the impregnation layer 4 arranged opposite and / or on and / or above the free spaces 243.

[0134] Preferably, each first activation zone 42a extends from the first conductive pole 241 to the second conductive pole 242 of a galvanic couple 240. More preferably, each first activation zone 42a is arranged opposite a part of a first conductive pole 241, a part of the free space 243 and a part of a second conductive pole 242 of a galvanic couple 240. In such a way, when activation product is applied at the first activation zone 42, the first conductive pole 241 and the second conductive pole 242 of each galvanic couple 240 are correctly connected to allow an oxidation-reduction reaction. More precisely, at the time of activation (of putting the device into operation), the activation product will make it possible to bring the first and second conductive poles 241, 242 into electrical contact by filling the free space 243, initially insulating.

[0135] According to a certain embodiment, for a galvanic couple 240, a first activation zone 42a comprises a zone of the impregnation layer 4 located opposite (i.e. covering) the entire galvanic couple 240, namely its first conductive pole 241, its second conductive pole 242 and its free space 243.

[0136] A second activation zone 42b corresponds to the zone of the impregnation layer 4 arranged at the level of the main electrode 22, as can be seen in FIG. 2 for example. A third activation zone 42c corresponds to the zone of the impregnation layer 4 arranged at the level of the counter-electrode 23.

[0137] By "at the level", it is understood that the third and second activation zones 42b, 42c correspond respectively to the zones of the impregnation layer 4 arranged opposite and / or on and / or above the main electrode 22 and the counter-electrode 23.

[0138] As explained previously, the impregnation layer 4 can be monolithic.

[0139] According to another embodiment not illustrated, the impregnation layer comprises a plurality of impregnation films. In other words, the impregnation layer is then not monolithic but comprises at least two, preferably three, distinct impregnation films separated from each other. For example, the impregnation layer comprises three impregnation films including a first impregnation film intended to cover the main electrode, a second impregnation film intended to cover the counter-electrode and a third impregnation film intended to cover the current generator. Advantageously, the first, second and third impregnation films are not in contact with each other. This embodiment is for example suitable in the case where the activation product has a low viscosity (it is therefore liquid, fluid, for example in the form of serum or solution).Indeed, in this case, when the activation product is applied to an activation zone (i.e. to all or part of this zone) of the impregnation layer 4, the activation product tends to spread. The fact that the impregnation films are not in contact makes it possible to prevent the activation product from spreading undesirably to other zones of the impregnation layer 4, in particular to zones which are not activation zones 42.

[0140] In the case where the impregnation layer comprises a plurality of impregnation films, the impregnation films are not necessarily made of the same material. However, for reasons of simplicity and cost, three separate but identical films (made of the same material) may be used.

[0141] The device 1 comprises a stencil layer 6 at least partially covering the impregnation layer 4. The stencil layer 6 comprises at least one stencil film 61.

[0142] The stencil layer 6 comprises at least one permeable zone 62 adapted to allow electrically conductive activation product to pass only at the level of predefined zones of the impregnation layer 4 called “free zones 44”.

[0143] Preferably, the stencil layer 6 comprises a plurality of permeable zones 62 and to each permeable zone 62 of the stencil layer 6 corresponds a free zone 44 of the impregnation layer 4. In other words, the free zone 44 of a permeable zone 62 is the zone of the impregnation layer 4 at which the permeable zone 62 is located. By "at" is meant "facing", "above" and / or "on". The free zone 44 has a surface and a shape identical to the permeable zone 62. The permeable zone 62 makes the free zone 44 accessible to an activation product which would be applied to the permeable zone 62. The stencil layer 6 has in particular the role of allowing the activation of only the activation zones 42, and of protecting the other zones from the activation product. The stencil layer 6 aims to prevent the application of activation product to areas of the impregnation layer 4 which are not activation areas 42.This allows the designers of the device 1 to determine which areas will or will not be in contact with the activation product, regardless of the user's handling and skills. This results in great simplicity of use of the device 1 and great reliability.

[0144] For this, the stencil layer 6 comprises permeable zones 62. The permeable zones 62 allow the circulation of activation product through the stencil layer 6, towards the impregnation layer 4 during an application of activation product on the stencil layer 6. The permeable zones 62 are for example made of a porous material.

[0145] The remainder of the stencil layer 6, i.e. the impermeable zones 63, are preferably made of a material which would prevent any circulation of activation product towards the impregnation layer 4 during an application of activation product on the stencil layer 6 at these impermeable zones 63.

[0146] Advantageously, as can be seen in the various figures, the permeable zones 62 are openwork zones, preferably formed by holes (or openings or cutouts) made in the stencil film 61. In other words, the permeable zones 62 are empty zones. A stencil film 61 is therefore openwork, i.e. perforated, at the level of a permeable zone 62. In other words, the permeable zones 62 reveal the free zones 44 of the impregnation layer 4. The permeable zones 62 are thus, in terms of shape, complementary to the free zones 44.

[0147] Each free zone 44 comprises at least one activation zone 42. A free zone 44 typically has a surface area smaller than or identical to that of a corresponding activation zone 42.

[0148] The free zones 44 are adapted to allow impregnation with activation product at the activation zones 42. By applying activation product to a permeable zone 62 and therefore at a corresponding free zone 44, it is expected that the activation product will impregnate a corresponding activation zone 42. More precisely, the free zone 44 may be smaller than the activation zone 42 in the case of a liquid activation product. Indeed, in this case, it is expected that the activation product having reached the free zone 44 will spread (by capillarity) beyond the free zone 44 and impregnate at least the corresponding activation zone 42. Furthermore, the free zone 44 may have a size substantially identical to that of the activation zone 42 in the case of a viscous activation product, such as for example a gel or a cream.Indeed, in this case, it is not expected that the activation product having reached the free zone 44 will spread beyond the free zone 44 so that it is preferred that the free zone 44 corresponds substantially to the activation zone 42.

[0149] Preferably, at least one free zone 44, called “first free zone 44a”, comprises at least a portion of the first activation zone 42a. In other words, a permeable zone 62, called “first permeable zone 62a”, is located opposite at least a portion of the first activation zone 42a. Thus, at least one first permeable zone 62 is located opposite at least a portion of the free space 243 of a galvanic couple 240.

[0150] Advantageously, a first permeable zone 62a, and therefore a corresponding first free zone 44a, is located opposite each free space 243 of the support layer 2. In such a way, the stencil layer 6 is provided to allow the activation of each galvanic couple 240.

[0151] According to one embodiment, a first permeable zone 62a, and therefore a corresponding first free zone 44a, is only arranged opposite a part of a free space 243 and the length of the first permeable zone 62 (and therefore also of the first free zone 44a) is less than the length of the free space 243. The surface area of ​​the first permeable zone 62a, and therefore of the first free zone 44a, is thus less than the surface area of ​​the first activation zone 42a. This scenario is suitable, for example, when an activation product is not very viscous and therefore very liquid, such as a physiological serum or a saline solution. Indeed, in this case it is sufficient to initially apply the activation product to a first free zone 44a corresponding to a small part of the first activation zone 42a because the activation product will spread so as to impregnate at least the first activation zone 42a of the impregnation layer 4.

[0152] According to another embodiment illustrated in Figure 2, a first permeable zone 62a is arranged opposite at least 20% of the total surface area of ​​the first activation zone 42a. The corresponding first free zone 44a therefore has a surface area of ​​at least 20% of the total surface area of ​​the first activation zone 42a. In other words, the first permeable zone 62a, and therefore also the first free zone 44a, is arranged opposite a part of a galvanic couple 240 which extends from the first conductive pole 241 to the second conductive pole 242. The first permeable zone 62a can also be arranged opposite a part of a galvanic couple 240 so as to be opposite a part of a first conductive pole 241, a part of the free space 243 and a part of a second conductive pole 242 of a galvanic couple 240. This scenario is for example suitable when an activation product is viscous.Indeed, in this case it is necessary to initially apply activation product to the first free zone 44a which has a surface area of ​​at least 20% of the surface area of ​​the first activation zone 42a to impregnate at least the first activation zone 42a with the impregnation layer 4 because the activation product will spread little.

[0153] It is thus understood that the dimensioning of the permeable zones 62 of the stencil layer 6 is correlated, in particular, with the viscosity of the activation product. Indeed, the more viscous, pasty, thick the activation product is, as would be the case for example with a cream or a gel, the less it will spread (diffuse) in the impregnation layer 4, therefore it is appropriate to maximize the size of the permeable zones 62. Conversely, the more liquid, fluid the activation product is, the more it will spread (diffuse) in the impregnation layer 4, in particular by capillarity, therefore it is appropriate to minimize the size of the permeable zones 62.

[0154] In the example illustrated in Figure 2, the first permeable zones 62a are rectangular in shape. Each first permeable zone 62a has a length approximately equal to 7 mm and a width approximately equal to 2 mm. Each first permeable zone 62a is designed so that each corresponding first free zone 44a is arranged opposite a portion of a first conductive pole 241, a portion of the free space 243 and a portion of a second conductive pole 242 of a galvanic couple 240, each of these portions having an advantageously similar surface area.

[0155] Advantageously, the stencil layer 6 further comprises permeable zones 62 arranged opposite the main electrode 22 and / or the counter-electrode 23. The impregnation layer 4 therefore comprises corresponding free zones 44.

[0156] Preferably, a second permeable zone 62b is arranged opposite the second activation zone 42b which is arranged at the level of the main electrode 22. The impregnation layer 4 therefore comprises at least one second free zone 44b corresponding to the second permeable zone 62b located opposite said second free zone 44b. TJ

[0157] Also preferably, a third permeable zone 62c is arranged opposite the third activation zone 42c which is arranged at the level of the counter-electrode 23. The impregnation layer 4 therefore comprises at least one third free zone 44c corresponding to the third permeable zone 62c located opposite said third free zone 44c.

[0158] Thus, an activation product can be applied to these permeable zones 62b, 62c so that the activation product impregnates the second free zone 44b and third free zone 44c and, consequently, impregnates the second activation zone 42b and third activation zone 42c to allow the circulation of electric current via the electrodes 22, 23 when the device 1 is applied to the skin of a user.

[0159] Preferably, the second permeable zone 62b has a shape similar to that of the main electrode 22. The second free zone 44b therefore has a shape similar to that of the main electrode 22. Also preferably, the third permeable zone 62c has a shape similar to that of the counter-electrode 23. The third free zone 44c therefore has a shape similar to that of the counter-electrode 23.

[0160] The stencil layer 6 preferably comprises a stencil film 61. The stencil layer 6 may also comprise a plurality of stencil films 61, each of which may comprise one or more permeable zones 62.

[0161] Whatever the embodiment of the stencil layer 6 detailed above, it is understood that the latter allows the user to apply cosmetic composition comprising ascorbic acid and / or one of its derivatives (also called activation product) to the entire device 1, on the stencil layer 6, without having to worry about the areas to be activated or not and without taking special precautions to avoid a continuity of cosmetic between the main electrode 22 and the counter electrode 23. Indeed, it is the permeable areas 62 and the impermeable areas 63 of the stencil layer 6 which allow the activation product to pass through to the activation area(s) 42 or on the contrary to prevent the activation product from reaching the other areas.In other words, the stencil layer 6 makes it possible to guide the activation product towards areas previously defined by the designers of the device 1, in this case the activation areas 42. The stencil layer 6 is preferably adapted to be removed from the device 1 before the application of the device 1 to the skin of a user. Indeed, the stencil layer 6 aims in particular to allow the application of activation product to the free areas 44 of the impregnation layer 4 so as to allow the impregnation of the activation areas 42. Once the user has applied the activation product to the stencil layer 6 and indirectly to the free areas 44 of the impregnation layer 4, the stencil layer 6 can be removed.

[0162] This can in particular make it possible to discover the second and third activation zones 42b, 42c. Thus, according to one embodiment, the total surface of the electrodes 22, 23 can be applied in contact with the skin.

[0163] Furthermore, this makes it possible to keep on the device 1 only the activation product necessary for the operation of the device 1 and not the activation product which would have been applied to impermeable zones 63. This guarantees that no activation product remains on unwanted zones, which limits the risk of short circuits occurring when using the device 1.

[0164] The stencil layer 6 is preferably flexible. The stencil layer 6 is for example made of a flexible plastic such as polyethylene terephthalate (PET). The stencil layer 6 preferably has a thickness of less than 50 μm. The thickness of the stencil layer 6 is typically greater than 30 μm, preferably approximately equal to 40 μm.

[0165] Thus, the stencil layer 6 makes it possible, thanks to a remarkable combination of permeable zones 62 and impermeable zones 63 judiciously sized and positioned, to guide (i.e. to let through) the cosmetic composition (which plays the role of activation product) only towards the activation zones 42 comprising, in this case, a part of the free space 243, and preferably, a part of a first conductive pole 241, a part of a second conductive pole 242 of a galvanic couple 240, and advantageously the main electrode 22 and the counter electrode 23; and on the contrary, to preserve the other zones (other than the activation zones 42) of the cosmetic composition.

[0166] Device 1 advantageously comprises:

[0167] - a support layer 2 comprising at least one support film 21 and comprising a main electrode 22, a counter-electrode 23 and a current generator 24 electrically connected to the main electrode 22 on the one hand and to the counter-electrode 23 on the other hand, the current generator 24 comprising at least one galvanic couple 240, the galvanic couple 240 being formed of a first conductive pole 241 forming a cathode and a second conductive pole 242 forming an anode separated from each other by a free space 243;

[0168] - an impregnation layer 4 comprising at least one impregnation film 41, the impregnation layer 4 covering at least the main electrode 22, the counter-electrode 23 and the current generator 24, preferably at least one impregnation film is made of non-woven material;

[0169] - a stencil layer 6 covering the impregnation layer 4 and comprising at least one stencil film 61, the stencil layer 6 comprising at least one permeable zone 62 adapted to allow the electrically conductive cosmetic composition to pass only at the level of at least one predefined zone of the impregnation layer 4, called free zone 44, the free zone 44 being intended to be covered with the cosmetic composition, optionally the stencil layer 6 is adapted to be removed so that said stencil layer 6 no longer covers the impregnation layer 4.

[0170] Advantageously, the device 1 comprises contact and holding means to ensure contact between the device 1 and the user's skin and to hold the device 1 on the skin despite possible external disturbances (wind, clothing, hair, etc.).

[0171] The contact means comprise, for example, an elastic band. For example, in the case of a device 1 in the form of a face mask, the device 1 may comprise an elastic band which would surround the head to press the device 1 against the face.

[0172] Preferably, the contact means comprise an adhesive layer 5. The adhesive layer 5 is preferably arranged between the impregnation layer 4 and the stencil layer 6. The adhesive layer 5 comprises at least one adhesive film 51.

[0173] The adhesive layer 5 preferably comprises at least one permeable zone 52 adapted to allow an activation product to pass only at the level of at least one activation zone 42. The permeable zone 52 is preferably perforated, for example by being formed by a hole (or an opening) made in the adhesive film 51.

[0174] The adhesive layer 5 preferably has a shape similar to the stencil layer 6. Preferably, the adhesive layer 5 covers the impregnation layer 4 located on the current generator 24 (except the free zones 44). The adhesive layer 5 is arranged on and in contact with at least a portion of the impregnation layer 4. The adhesive layer 5 does not cover the portions of the impregnation layer 4 located opposite the main electrode 22 and the counter electrode 23, in order to allow good current flow between the electrodes 22 and 23 and the skin.

[0175] Thus, the adhesive layer 5 ensures that the device 1 is held on the skin while isolating the galvanic couples 240 from the skin and allowing the activation of each galvanic couple 240 via the free zones 44. The galvanic couples 240 being isolated from the skin by the adhesive layer 5, the risk of short circuit within the latter is eliminated and the risk of seeing redness appear on the skin is reduced.

[0176] The adhesive layer 5 has an external adhesive surface 53 intended to come into contact with the user's skin and to ensure the attachment of the device 1 to the skin for the entire duration of the treatment.

[0177] Advantageously, the stencil layer 6 constitutes a cover for the adhesive layer 5. In other words, when the stencil layer 6 is removed from the device 1, the adhesive external surface 53 of the adhesive layer 5 is uncovered and can then be stuck to the user's skin.

[0178] The adhesive layer 5 therefore also remarkably allows the stencil layer 6 to be held on the device 1 before the stencil layer 6 is removed from the device 1. The stencil layer 6 and the adhesive layer 5 therefore play a respective role towards one another: the stencil layer 6 protects the adhesive outer surface 53 of the adhesive layer 5, in particular from dust, thus preserving its adhesive power, while the adhesive outer surface 53 ensures the holding of the stencil layer 6 while waiting for the user to remove it during the actual use of the device 1.

[0179] The adhesive layer 5 advantageously furthermore has an internal adhesive surface intended to come into contact with the impregnation layer 4, and thus ensure its attachment to the latter. Preferably, the adhesive layer 5 is then formed by a double-sided adhesive film 51, that is to say a film having an external adhesive surface 53 intended to be in contact with the skin and an internal adhesive surface intended to be in contact with the impregnation layer 4. The adhesive layer 5 preferably has a thickness of less than 150 μm. The thickness of the adhesive layer is for example approximately equal to 140 μm.

[0180] Consequently, the total thickness of the device 1 (i.e. of the stack of layers previously described) is less than 3 mm, preferably even less than 2 mm. The device 1 is thus flexible and can therefore conform to the shape of the area of ​​the body on which it will be placed.

[0181] The device capable of implementing the method of the invention is not limited to the embodiments described and represented in the appended figures. Modifications remain possible, in particular from the point of view of the constitution of the various technical characteristics or by substitution of technical equivalents, without departing from the general teaching.

[0182] Cosmetic composition

[0183] The cosmetic composition comprising ascorbic acid and / or one of its derivatives is suitable for an iontophoretic process. It further comprises one or more cosmetically acceptable additives.

[0184] Advantageously, the cosmetic composition comprises 0.001 to 20.0% by weight, preferably 0.1 to 10.0% by weight, more preferably 0.3% to 2.0% by weight of ascorbic acid and / or one of its derivatives relative to the total weight of the composition.

[0185] Ascorbic acid and ascorbyl glucoside have a first pKa of 4.1 and 3.4, respectively. Therefore, ascorbic acid and its derivatives are good candidates for iontophoresis since these molecules are negatively charged at pH above 4.5.

[0186] Advantageously, the cosmetic composition has a pH of between 4.5 and 10, in particular between 5.0 and 7, preferably between 5.5 and 6.5.

[0187] The composition may further comprise one or more polar solvent(s), preferably present in an amount of at least 30% by weight, preferably in an amount of at least 40% by weight, and more preferably in an amount of at least 50% by weight, relative to the total weight of the composition. Preferably, the polar solvent(s) is(are) chosen from water, a hydrosol, a distillate and mixtures thereof. As hydrosol that can be used in the context of the present invention, mention may be made of rose hydrosol, tea hydrosol, eucalyptus hydrosol or lavender hydrosol.

[0188] Advantageously, the cosmetic composition comprises at least 30% by weight, preferably at least 60% by weight and more preferably at least 80% by weight of water relative to the total weight of the composition.

[0189] The composition is, for example, free of any ionizable preservative.

[0190] As is known, the galenic forms dedicated to topical administration may also contain conventional adjuvants in the cosmetic and / or dermatological field such as stabilizers, antioxidants, solvents, perfumes, chelating agents, surfactants and silicone oils, this list not being exhaustive. Such a composition may be in the form of an aqueous, hydroalcoholic solution or gel, a solution or dispersion of lotion or serum type, an emulsion of liquid or semi-liquid consistency of milk type, obtained by dispersion of a fatty phase in an aqueous phase (OAV) or vice versa (W / O), or a suspension, or emulsion, of soft, semi-solid consistency, of the cream, aqueous or anhydrous gel type, a microemulsion, a microcapsule, a microparticle, or a vesicular dispersion of ionic and / or non-ionic type.

[0191] These compositions are prepared according to the usual methods known to those skilled in the art.

[0192] Process for the derivation of ascorbic acid and / or one of its derivatives

[0193] The first subject of the invention relates to a non-therapeutic cosmetic process for delivering ascorbic acid and / or one of its derivatives through the skin by iontophoresis, preferably bipolar, and / or electrostimulation comprising the following steps:

[0194] • Providing a device comprising a main electrode, a counter-electrode and a power source electrically connected to the main electrode on the one hand and to the counter-electrode on the other hand, the main electrode and the counter-electrode being intended to be in direct or indirect contact with the skin and being separated from each other by a free space; • Applying a cosmetic composition comprising ascorbic acid and / or one of its derivatives and one or more cosmetically acceptable additives to the main electrode and the counter-electrode but not to the free space;

[0195] • Apply said device to the skin so that the main electrode and the counter electrode with the cosmetic formulation are in direct or indirect contact with the skin;

[0196] • Apply a direct current with an average current density of 0.03 mA / cm over a certain time range 2 at 0.5mA / cm 2, preferably 0.1 mA / cm 2 at 0.2 mA / cm 2 .

[0197] As explained previously, the Applicant has surprisingly discovered that the area of ​​application of the cosmetic composition comprising ascorbic acid and / or one of its derivatives is crucial. In particular, it is essential to apply the cosmetic composition to both electrodes without there being any continuity of cosmetic composition between the main electrode and the counter electrode. This particular application makes it possible to generate a much better penetration of the active ingredient, i.e. ascorbic acid and / or one of its derivatives, into the skin, whether compared to an application on one of the two electrodes or on both electrodes with a continuity of cosmetic composition between the electrodes.

[0198] This application allows the use of both the electro-migration and electroosmosis mechanisms in a combined manner. Indeed, the isoelectric point of the skin is 4.5. Thus, it has a natural negative charge which will induce a transport value of Na+ ions higher than that of Cl- ions. Since Na+ ions are very mobile, they will create a charge deficit on the anode side. Thus, an electroosmotic flow will naturally be created from the anode to the cathode when a current is applied, carrying with it both charged and neutral molecules and molecules with higher molecular weights (see figure 15).

[0199] The application of the cosmetic composition can be done directly on the electrodes or, when present, on the impregnation layer opposite the electrodes.

[0200] Consequently, when the method implements the device 1, the free zones 44 allow impregnation with cosmetic composition at the activation zones 42. By applying cosmetic composition to a permeable zone 62 and therefore at a corresponding free zone 44, it is expected that the cosmetic composition impregnates a corresponding activation zone 42 as described previously. This device thus makes it possible to control the application of the cosmetic composition to the electrodes and in addition to control the moment of activation of the device.

[0201] The user therefore applies the cosmetic composition to the device 1 so as to cover at least the permeable zone(s) 62 of the stencil layer 6 and therefore the corresponding free zone(s) 44 of the impregnation layer 4. The cosmetic composition then impregnates the free zones 44 and, consequently, the activation zones 42 of the impregnation layer 4.

[0202] Regardless of the power source an electric current passes through the user's skin, this current can be generated directly in the device for example in the case of device 1.

[0203] This current is a direct current with an average current density of 0.03 mA / cm 2 at 0.3 mA / cm 2 , preferably 0.1 mA / cm 2 at 0.2 mA / cm 2 .

[0204] In some embodiments of the iontophoresis method, the current is applied for from 30 seconds to 120 minutes, preferably from 2 minutes to 50 minutes, and more preferably from 3 minutes to 40 minutes.

[0205] When the device comprises a stencil layer, the method according to the invention may comprise an additional step, which is subsequent to the application of the cosmetic composition, of removing the stencil layer so that the stencil layer no longer covers the impregnation layer.

[0206] Kit i

[0207] A second subject of the invention relates to an iontophoretic kit comprising:

[0208] • A cosmetic composition suitable for an iontophoretic process comprising ascorbic acid and / or one of its derivatives and one or more cosmetically acceptable additives, and

[0209] • An iontophoretic device for implementing the method according to the invention.

[0210] Preferably, the cosmetic composition is as defined above. EXAMPLES

[0211] Example 1: examples of cosmetic compositions suitable for the process according to the invention

[0212] Table 1

[0213] PBS: phosphate buffered saline, 1: Polysurf 67 (cetyl hydroxyethylcellulose) (5%)

[0214] Example 2: Study of skin penetration by iontophoresis of ascorbyl glucoside depending on the method of application of the cosmetic composition

[0215] Materials and methods

[0216] This study is carried out with Àg / ÀgCL electrodes with a carbon coating.

[0217] Franz cells are placed in a 37°C water bath in a room temperature room. The skin type is pig belly skin. The receptor fluid is 7.4-phosphate buffered saline.

[0218] The composition used is composition E from example 1. It has the following properties:

[0219] - Viscosity at 100 s 1 : 1600 mPa.s,

[0220] Tensile force at 0.5 mm / s: 0.32 N, Conductivity: 8670 pS / cm at 27 °C,

[0221] - pH: 5.94. A control composition (without ascorbyl glucoside) was also prepared with 2% hydroxyethylcellulose in PBS.

[0222] Detection is done by high performance liquid chromatography with UV detection (HPLC-UV) with the following parameters:

[0223] Column: Waters XSelect CSHTM Fluoro-Phenyl 3.5pm 4.6 x 150mm,

[0224] Temperature: 30°C,

[0225] Injection volume: 20 pL,

[0226] Mobile phase: 100% water + 0.1% formic acid,

[0227] Flow rate: 1 mL / min,

[0228] Wavelength: 240 nm.

[0229] Two different current densities are applied in direct current: 0.2mA / cm 2 and 0.1 mA / cm 2 The current is applied for 30 minutes and then the different sub-layers of the skin are divided at t = 4h.

[0230] Different modes of application of the composition are then tested as summarized in Table 2.

[0231] Table 2

[0232] The active electrode corresponds to the cathode and the passive electrode corresponds to the anode.

[0233] The application mode AÀ SC therefore corresponds to an application of composition E on the two electrodes "without contact", that is to say without composition continuity between the two electrodes. The application mode AÀ ÀC therefore corresponds to an application with composition continuity E between the two electrodes. The two modes ÀSA SC and ASA SC2 are two non-contact modes with each of the two electrodes with composition E or control composition. For ÀSA SC, composition E is applied to the active electrode and the control composition to the passive electrode, and vice versa for ASA SC2. The application modes are also summarized in Figure 8. As for the passive ones, they correspond to applications without contact and without application of a current.

[0234] Figure 9 shows that the penetration of the active ingredient is not improved when there is contact with the electrodes (AA AC), regardless of the current applied.

[0235] For the Franz cell receptor fluid (LR) and the dermis, there is considerable benefit in applying a direct current for 30 minutes when there is no contact between the electrodes. For the receptor fluid, however, this result is not improved when the applied current density is increased by 0.1 mA / cm 2 at 0.2 mA / cm 2 On the contrary, for the dermis, we see that the application of a weaker current allows more active ingredient to penetrate.

[0236] For the epidermis, the same conclusions are reached as for the dermis, i.e. the AA SC application method allows for a considerable increase in skin penetration with optimum penetration for a current density of 0.1 mA / cm 2. The AA AC contact mode does not allow better penetration of ascorbyl glucoside into the epidermis than the passive mode 1 .

[0237] The results presented in Figure 10 allow us to probe the impact of the two main mechanisms of iontophoresis, electrorepulsion and electroosmosis, on the penetration of the active ingredient. The ASA SC application mode allows us to probe the electrorepulsion phenomenon and the ASA SC2 mode allows us to probe the electroosmosis phenomenon.

[0238] The results indicate that there is better skin penetration via the electrorepulsion phenomenon compared to the electroosmosis phenomenon in the Franz cell receptor fluid and at both applied current densities. On the other hand, in the dermis, viable epidermis and stratum corneum, whether for electrorepulsion or electroosmosis, the penetration of the active ingredient is not improved at both applied current densities. In all cases, the results at both current densities are the same and the penetration of the active ingredient is not improved in either case.

[0239] Figure 11 shows the comparison of the skin penetration of the active ingredient between the “contactless” application mode and the sum of the “contact” modes. Whether in the LR, in the dermis or in the dermis, the penetration of the active ingredient is significantly higher with the contactless mode compared to the sum of the contact modes. It even seems that the two phenomena taken separately do not generate any additional penetration of active ingredient compared to the passive one. In other words, the contactless application mode with the composition comprising the active ingredient on the two electrodes makes it possible to obtain a synergistic effect on the penetration of ascorbyl glucoside into the skin compared to the simple accumulation of the electro-osmosis and electro-repulsion phenomena.

[0240] Figure 12 shows the skin penetration results of ascorbyl glucoside in the dermis, epidermis and receptor fluid at different current densities applied in the AÀ SC application mode. Regarding the epidermis, the application of a current (even at a low current density such as 0.033 mA / cm 2 ) has an impact on the skin penetration of ascorbyl glucoside. It should be noted that the penetration of the active ingredient is significantly increased at current densities close to 0.1 mA / cm 2 . Regarding the receiving liquid and the dermis, the penetration of the active is remarkably increased compared to the passive at current densities close to 0.1 mA / cm 2 and 0.2 mA / cm 2 .

Claims

CLAIMS 1. Non-therapeutic cosmetic process for delivering ascorbic acid and / or one of its derivatives through the skin by iontophoresis and / or electrostimulation comprising the following steps: • Provide a device (0) comprising a main electrode (22), a counter-electrode (23) and a power source electrically connected to the main electrode (22) on the one hand and to the counter-electrode (23) on the other hand, the main electrode (22) and the counter-electrode (23) being intended to be in direct or indirect contact with the skin and being separated from each other by a free space (25); • Applying a cosmetic composition comprising ascorbic acid and / or one of its derivatives and one or more cosmetically acceptable additives to the main electrode (22) and the counter-electrode (23) but not to said free space (25); • Applying said device (0) to the skin so that the main electrode (22) and the counter electrode (23) with the cosmetic formulation are in direct or indirect contact with the skin; • Apply a direct current with an average current density of 0.03 mA / cm over a certain time range 2 at 0.5 mA / cm 2 , preferably 0.1 mA / cm 2 at 0.2 mA / cm 2 .

2. Method according to claim 1, wherein a direct current is applied for from 30 seconds to 120 minutes, preferably from 2 minutes to 50 minutes and more preferably from 3 minutes to 40 minutes.

3. Method according to any one of the preceding claims, said composition comprising 0.001 to 20.0% by weight, preferably 0.1 to 10.0% by weight, more preferably from 0.3% to 2.0% by weight of ascorbic acid and / or one of its derivatives relative to the total weight of the composition.

4. Method according to any one of the preceding claims, said composition comprising one or more polar solvents.

5. Method according to any one of the preceding claims, said composition comprising at least 30% by weight, preferably at least 60% by weight and more preferably at least 80% by weight of water relative to the total weight of the composition.

6. A method according to any one of the preceding claims, wherein the cosmetic composition comprises ascorbyl glucoside.

7. Method according to any one of the preceding claims, in which the device comprises an impregnation layer covering at least the main electrode (22) and the counter electrode (23).

8. Method according to any one of the preceding claims, wherein the power source of the device (0) is a current generator which is activated by the application of the cosmetic composition.

9. Method according to claim 8, wherein the device is a device (1) comprising: - a support layer (2) comprising at least one support film (21) and comprising a main electrode (22), a counter-electrode (23) and a current generator (24) electrically connected to the main electrode (22) on the one hand and to the counter-electrode (23) on the other hand, the current generator (24) comprising at least one galvanic couple (240), the galvanic couple (240) being formed of a first conductive pole (241) forming a cathode and a second conductive pole (242) forming an anode separated from each other by a free space (243); - an impregnation layer (4) comprising at least one impregnation film (41), the impregnation layer (4) covering at least the main electrode (22), the counter-electrode (23) and the current generator (24), preferably at least one impregnation film is made of non-woven material; - a stencil layer (6) covering the impregnation layer (4) and comprising at least one stencil film (61), the stencil layer (6) comprising at least one permeable zone (62) adapted to allow the electrically conductive cosmetic composition to pass only at the level of at least one predefined zone of the impregnation layer (4), called free zone (44), the free zone (44) being intended to be covered with the cosmetic composition, optionally the stencil layer (6) is adapted to be removed so that said stencil layer (6) no longer covers the impregnation layer (4).

10. Method according to claim 9, in which a permeable zone (62) comprises an openwork zone and / or at least one permeable zone (62) is located opposite at least a portion of the free space (243) of the galvanic couple (240).

11. Method according to claim 10, in which at least one permeable zone (62) located opposite at least a part of the galvanic couple (240) extends in the free space (243) at least from the first conductive pole (241) of the galvanic couple (240) to the second conductive pole (242) of the galvanic couple (240).

12. Method according to any one of claims 9 to 11, in which the stencil layer (6) comprises a permeable zone (62) facing the main electrode (22) and a permeable zone (62) facing the counter-electrode (23).

13. Method according to any one of claims 9 to 12, wherein the main electrode (22) and the counter electrode (23) comprise silver and / or silver chloride, each first conductive pole (241) forming a cathode comprises silver and / or silver chloride and each second conductive pole (242) forming anode comprises zinc.

14. Method according to any one of claims 9 to 13, in which the support layer (2) comprises a plurality of galvanic couples (240) connected in series, preferably via carbon connectors (246).

15. Method according to any one of claims 9 to 14, wherein the main electrode (22) is electrically connected to a second conductive pole (242) via a carbon connector and the counter electrode (23) is electrically connected to a first conductive pole (241) via a silver and / or silver chloride connector.

16. Method according to any one of claims 9 to 15, wherein the device (1) comprises an adhesive layer (5) arranged between the impregnation layer (4) and the stencil layer (6), the adhesive layer (5) comprising at least one adhesive film (51), the adhesive layer (5) comprising at least one permeable zone (62) adapted to allow the cosmetic composition to pass only at the level of at least one predefined zone of the impregnation layer (4), called the free zone (44), the adhesive layer (5) having an external adhesive surface (53) intended to come into contact with the user's skin.

17. Method according to any one of claims 9 to 16, comprising a step of removing the stencil layer (6) before applying the device (1) to the skin.

18. Iontophoretic kit including: • A cosmetic composition suitable for an iontophoretic process comprising ascorbic acid and / or one of its derivatives and one or more cosmetically acceptable additives, and • An iontophoretic device for implementing the method according to any one of claims 1 to 17.

Images