WO2000010640A1

WO2000010640A1 - Method and device for topical administration of substances

Info

Publication number: WO2000010640A1
Application number: PCT/IL1998/000395
Authority: WO
Inventors: Mark Litvak; Miriam Valchikhin
Original assignee: Gal-Ion Blaze Ltd.
Priority date: 1998-08-19
Filing date: 1998-08-19
Publication date: 2000-03-02
Also published as: AU8820198A

Abstract

An electric field driven emitter electrode is used for the topical administration of a useful substance to a target portion of a subject's body surface. In operation an electric field of 1,000-15,000 volt is created whereby the useful substance is ionized. The emitter electrode is capable of holding a required amount of the useful substance and is fitted with capillary tubes or rods for the emission of ionized molecular particles. Optionally there is provided a counter electrode.

Description

METHOD AND DEVICE FOR TOPICAL ADMINISTRATION OF SUBSTANCES

FIELD OF THE INVENTION

The present invention concerns a method and device for the administration of a useful substance into and across a body surface such as the skin, the eyes, the inner ear, the nose or the respiratory tract, by use of a strong electric field. The term "useful substance" used herein denotes quite generally any substance for medical or cosmetic treatment of humans and non human animals.

BACKGROUND OF THE INVENTION It is known to administer medicaments to humans transdermally by means of electrically induced electrophoretic migration, a technique which is also referred to as iontophoresis. In accordance therewith, a liquid or pasty aqueous dispersion containing the substances to be administered in ionic form, is spread on the skin, an electrode capable of generating an electric field, sometimes referred to as applicator electrode is placed on top of the dispersion and a relatively weak electric field is applied whereby the ionic substance migrates across the subject's skin. In the performance of this method the subject's skin may serve as ground. Alternatively, a second electrode of opposite polarity, referred to sometimes as return electrode, is applied to the skin in the proximity of the first electrode, whereby the rate of ionic migration is enhanced. U.S. 5,037,380 discloses an iontophoretic electrode which includes a pouch for holding a solution of an ionic medicament. With such an electrode, the ionic medicament migrates directly from the electrode's pouch across the skin and the need of first spreading the medicament on the skin is obviated. For the rest the mechanism is the same as in all other iontophoretic methods.

Due to the fact that in iontophoresis, the applicator electrode is in direct contact with the skin, only low voltages of say below 80 volts may be applied. In consequence, only such substances may be used which (i) are a priori present in ionic form and which (ii) can be induced to migrate under the applied low voltage. It is thus evident that there are serious limitations on the applicability of conventional iontophoresis.

Moreover, the fact that in conventional iontophoresis the applicator electrode is applied directly to the skin has the following additional disadvantages: i. Physical contact between the skin and electrode may be harmful and should be avoided where the skin to be treated is damaged due to burns, cuts, operational stitches, and also in cases where the subject has a high pain sensitivity. ii. It is inherent in iontophoresis that an electric current flows across the skin which often leads to the development of so-called iontophoretic burns, iii. Hydroxyl ions are produced as a result of current passage through the aqueous dispersion which may be harmful to the skin. iv. Iontophoresis is suitable only for systemic drug administration across the skin and is unsuitable for topical treatment of the skin only. SUMMARY OF THE INVENTION

It is the object of the present invention to provide an improved method for the administration of useful substances into and across a body surface, free of the shortcomings of iontophoresis. The invention is based on a novel concept whereby the desired useful substance is accelerated to the body surface from a distance under the influence of a strong electric field of the order of 1000-15,000 volts. Such a strong electric field is capable of imparting an electric charge to an a priori non-ionic substance and accelerate an ion towards the body surface, and also of accelerating towards the body surface an a priori ionized substance.

In accordance with the present invention, there are provided a method and apparatus for the topical administration of a medically or cosmetically useful substance to a human or non-human subject, wherein a member holding said useful substance and designed for the emission thereof, to be referred to hereinafter as "an electric field driven emitter electrode", is placed at a desired distance from a target portion of the subject's body surface, e.g. the skin, and subjected to the influence of an electric field within the range of 1000 to 15,000 volts either by directly connecting the electric field driven emitter electrode to an electric power source or by placing said emitter electrode in an electric field established between the electric power source and the subject's body surface. Ionized molecular particles of the useful substance are emitted from the emitter electrode and accelerated onto the subject's body surface.

Where the useful substance applied in accordance with the invention is non-ionic, the applied voltage must be strong enough for causing ionization of the useful substance.

Where the useful substance is a priori ionic, the applied voltage may possibly be lower than in the case of an a priori electrically neutral substance of similar molecular weight. In the course of operation, a beam of charged molecular particles is accelerated across the electric field from the electric field driven emitter electrode on to the body surface and depending on the desired effect, the strength of the electric field is so selected that the particles arrive at the body surface at a velocity suitable for either partial or complete penetration of the body surface. Thus, where for example it is desired to treat the skin itself, for either cosmetic or medical purposes, the object of the topical administration will be intradermal penetration, i.e. penetration into the skin and not across it. Where, on the other hand, it is desired to achieve transdermal penetration for the introduction of the useful substance into a subcutaneous tissue or into the blood stream, the strength of the electric field and with it the velocity of the particles will have to be increased accordingly.

Quite generally, the factors that have to be taken into consideration for a given treatment in accordance with the present invention, include the nature of the useful substance to be administered, i.e. whether it is a priori ionic or non-ionic, its molecular weight and the desired degree of penetration.

The useful substance may be used in raw or composite form and be present in the electric field driven emitter electrode in any desired solid or liquid aggregate form, e.g. in comminuted solid form, in form of a paste or gel, in form of a liquid, an aqueous or non-aqueous solution, dispersion or colloid.

Thus, in accordance with the present invention there is provided a method of topical administration of a useful substance to a subject for medical or cosmetic purposes, comprising placing at a distance from a target portion of the subject's body surface an electric field driven emitter electrode having a reservoir holding said useful substance, and putting the electric field driven emitter electrode under the influence of an electric field having an intensity within the range of from 1000 to 15,000 volts, whereby ionized molecular particles are emitted from said electric field driven emitter electrode to bombard said target portion of the subject's body surface to produce a desired medical or cosmetic effect.

The electric field driven emitter electrode may be connected directly to an electric power source so that the field lines of the electric field extend from the emitter to the body surface or, alternatively, may be unconnected to the power source and be placed in an electric field formed between the electric power source and the subject's body surface.

In accordance with one embodiment of the invention, the electric field driven emitter electrode is the only electrode of the system while in accordance with another embodiment, a second electrode is placed on the subject's body surface.

The useful substance for use in the performance of the method according to the invention may be pure or compounded and be in any desired solid or liquid aggregate form, e.g. in comminuted solid form, in form of a paste or gel, in form of a liquid, such as an aqueous or non-aqueous solution, a dispersion or a colloid.

Depending on the nature of the useful substance, the subject's body surface or a second electrode placed thereon will be either the positive or negative pole of the said electric field. As mentioned, the strength of the electric field is selected in accordance with the nature of the useful substance, its molecular weight and the desired depth of penetration, and may be determined by means of simple experimentation.

The invention further provides for use in the topical administration of a useful substance to a subject for medical and cosmetic purposes, an electrical field driven emitter electrode for bombarding a target portion of the subject's body surface with ionized molecular particles, comprising reservoir means for holding said useful substance, emitter means for the emission of ionized molecular particles of said useful substance, and optionally electrical terminal means for connection to an electric power source.

The invention further provides an assembly for bombarding a target portion of a subject's body surface with ionized molecular particles of a useful substance for medical and cosmetic purposes, comprising an electric field driven emitter electrode of the kind specified, spacer means having an open ended passageway for said ionized molecular particles, and an electric power source capable of creating an electric field of 1,000-15,000 volt.

In accordance with one embodiment of the assembly, the electric field driven emitter electrode is the only electrode of the system, the function of a second electrode being fulfilled by the subject's body surface.

In accordance with another embodiment, the assembly comprises a second electrode and an electric field is formed between the electric field driven emitter electrode and said second electrode, or alternatively between said electric power source and said second electrode, with the electric field driven emitter electrode being placed within the electric field. In accordance with such an embodiment, said second electrode may be located within said spacer means in such a way as to leave a free passageway for the ionized molecular particles, whereby said particles can proceed beyond said second electrode. For example, the second electrode in such an embodiment may be annular or in form of a plate or membrane with a suitably located hole or a plurality of holes.

If desired, the said reservoir means for holding a useful substance together with said emitter means may be in form of disposable cartridges.

Typically, the body surface treated in accordance with the present invention, is the skin with the administration of the useful substance being either intradermal or transdermal and serving for cosmetic or medical purposes. In accordance with one embodiment, the substance to be applied in accordance with the invention is placed directly into the reservoir, either in pure or composite form. In accordance with another embodiment applicable when the substance for administration is liquid or in the form of a liquid solution dispersion or emulsion, the reservoir contains an absorbent material, such as for example cotton, which is soaked with the substance for administration.

The invention is fundamentally distinguished from conventional, electrically driven transdermal drug administration methods such as iontophoresis. Thus, whereas in accordance with iontophoresis, an a priori ionized substance is applied to the skin, a low voltage electric current flows across the skin and the useful substance passes therethrough by electrophoretic migration, in accordance with the present invention a target portion of a body surface such as the skin, is bombarded from a distance with ad hoc or a priori ionized molecules of the desired useful substance by the action of a strong electric field of the order of 1,000 to 15,000 volts, and penetration of said substance into the surface and, if desired, across it results from the mechanical impact of the molecules bombarding the target portion of the subject's body surface. Apart from overcoming in this way the various shortcomings of the conventional iontophoretic techniques, the invention provides a high degree of versatility in that it broadens significantly the range of useful substances that may be administered in this way, and in that it enables for the first time to adjust the depth of penetration of the useful substance. Such adjustment was not possible in accordance with the prior art which invariably involves transdermal migration. Accordingly, the present invention opens a new area of surface treatment of a subject, both for cosmetic and medical purposes. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example only, with reference to the annexed drawings in which:

Fig. 1 shows one embodiment of an assembly according to the invention in the disassembled state, in cross-sectional and bottom view;

Fig. 2 shows a cross-sectional view of the same embodiment of Fig. 1 in the assembled state;

Fig. 3 shows a cross-sectional and bottom view of another embodiment of an assembly with an emitter electrode according to the invention; Fig. 4 shows a cross-sectional and bottom view of a first component of an emitter electrode according to the invention;

Fig. 5 shows in cross-section an assembled emitter electrode embodying the component of Fig. 4;

Fig. 6 shows schematically the emission pattern in an assembly of Fig. 5;

Fig. 7 is a diagram showing the rate of ionization as a function of the applied voltage; and

Fig. 8 is a diagram showing the depth of penetration as a function of time.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Attention is first directed to Figs. 1 and 2 which show one embodiment of an assembly according to the invention serving for bombarding a selected portion of a subject's body surface, e.g. of the skin, with electrically charged molecular particles. In Fig. 1 the assembly is shown in the disassembled state and in Fig. 2 in the assembled state. As shown, the assembly comprises an electric field driven emitter electrode 1 having a handle 2 and a head portion 3 all made of electrically insulating material. Head portion 3 comprises a reservoir chamber 4 covered by a lid 5 having a central hole 6 serving for the passage of a high voltage wire 7 and for charging the useful material. The electrically powered emitter electrode 1 further comprises a matrix portion 8 also made of insulating material and holding four capillary emitter tubes 9.

Inside chamber 4 there is located a metal plate 10 merging into four metal sleeves 11, each surrounding the end portion of one capillary emitter tube 9.

The assembly further comprises a spacer device 13 comprising a matrix 14 of insulating material and four tubular members 15 each capable of accommodating one of the capillary emitter tubes 9 in the manner shown in Fig. 2, which tubular members also serve as spacers.

In the assembled state of Fig. 2, the spacer device 13 is attached to the head portion 3 of the electrically powered emitter electrode 1 and is held in position by some suitable attachment means not shown. As shown in Fig. 2, each tubular member 15 accommodates one associated capillary emitter tube 9 and electrode 10 is connected by means of wire 7 to the negative pole of an electric power supply 17. As further shown, electric power supply 17 is connected by means of a wire 18 to an external second electrode 19 covered by an insulator layer 20, which second electrode 19 is in operation placed on the skin. In this arrangement the emitter electrode 1 is the negative one and electrode 19 the positive one.

In operation reservoir chamber 4 and each of the capillary tubes 9 are filled via the central hole 6 with a useful substance 21 to be employed for the desired treatment, the openings of the tubular members 15 of spacer device 13 being placed on a subject's skin portion to be bombarded. The second electrode 19 is also placed on the skin, off the portion to be bombarded and with the insulator plate 20 down on the skin. Upon actuation of a switch (not shown) the negative emitter electrode 1 and the second, positive electrode 19 become electrically charged resulting in the formation of an electric field. Assuming that the useful substance placed in reservoir 4 is a priori non ionic, the voltage will be relatively high, say about 6,000 to 8,000 volts which brings about ionization of the useful substance inside the capillary emitter tubes 9. As a result, the negatively ionized molecular particles of the useful substance are accelerated across the electric field established between the emitter electrode 1 and the skin, and they progress inside the tubular members 15 so as to impinge at high speed on to the skin.

The embodiment of the assembly according to the invention shown in Fig. 3 also embodies a capillary emitter tube. As shown, the electric field driven emitter electrode 31 comprises an electrode 32 having a base plate 33 and a cover plate 34 forming between them a reservoir chamber 35 merging into a capillary tube 36 accommodated within a larger tube 37. Within chamber 35 is located an annular electrode plate 38 with integral high voltage wire 39.

The electric field driven emitter electrode 32 is attached to a tubular spacer device 40 fitted with two sets of radial braces 41 and 42 and accommodating the tube 37. At its end the spacer device 40 comprises four feet 43. In operation, the desired useful substance is charged into reservoir chamber 35 and capillary tube 36, and the assembly is placed by means of feet 43 on a body surface portion, e.g. the skin, selected for bombardment by ionized molecular particles emitted by the capillary tube 36, and electrode 32 is connected to a high voltage electric power supply (not shown).

The embodiment of an electric field driven emitter electrode according to the invention shown in Figs. 4 and 5, comprises as a first component emitter electrode assembly 52 having a tubular portion 53 holding a filler of absorbent material soaked with the desired useful substance to be emitted. There are further provided four emitter rods 44 which in operation emit the ionized useful substance from their tree tips. The electrode assembly 52 further comprises a funnel shaped spacer portion 45 holding a second, annular electrode 46. If desired, the emitter electrode assembly 52 may be in form of a disposable cartridge.

The second component of the emitter electrode according to Figs. 4 and 5 is a tubular handle member 47 fitted with radial braces 48 and holding an electric conductor rod 49. The tubular member 47 comprises an integral inner annular rib 50 which serves for engagement between tubular portion 53 of the first component 52 and the handle member 47 of the second component.

In operation, the emitter electrode assembly 52 is connected via conductor rod 49 to one pole of a high electric voltage power supply (not shown) and the second, annular electrode 46 to the other poles. When the power is switched on ionized useful substance is emitted from the emitter rods

44 onto a skin portion 51 passing on its way across the annular electrode 46.

The manner in which ions arrive from an emitter rod 44 onto the skin 51 across a tubular electrode 46 is shown schematically in Fig. 6 and as shown, some of the ions penetrate the skin 51 while others bounce away. The useful substance particle arrives at the skin still in the charged form, but shortly after their arrival the ions lose their charge and revert to the neutral molecular state.

In accordance with the invention, a desired body surface portion may be bombarded with a large variety of substances such as, for example, 1. Aloe extract 21. Resorcin

2. Apy toxin 22. Ammonium rodanid

3. Sodium bromide 23. Sodium salicilat

4. Ascorbic acid 24. Saluzid

5. Sodium hydrocarbonate 25. Sulfuric water

6. Griseofulvin 26. Sorbit

7. Dichloramine 27. Sulfanilamide (including

8. Imanin streptocide)

9. Ichtiol 28. Tannin

10. Potassium iodide 29. Temisal

11. Potassium chloride 30. Tetraciklicin

12. Sodium coffein-benzoate 31. Sodium thiosulfate

13. Honey 32. Trypsin

14. Nicotinic acid 33. Sodium phosphate

15. Peloidin (grease extract) 34. Phtalasol

16. Paraaminosalicilic acid 35. Sodium phtorid

17. Penicillin 36. Phyrasolin

18. Blood plasma 37. Sodium chloride

19. Propolis 38. Citral

20. Etheric oils 39. Ecmolin

It should be noted that this list is far from exhaustive and that many other substances may be used. The substances in the above list are those which are filled into the reservoir of the emitter electrode. Some of the substances in the list such as sodium bromide, sodium hydrocarbonate, potassium iodide, potassium chloride and others are salts which are, a priori in ionized form. In case of such substances and assuming that the polarity of the electrode is negative, only the anionic moiety is emitted and is upon arrival at the skin, converted into the electrically neutral molecular form. As in the case of such a priori ionized substances there is no need for any ionization energy, the applied voltage and the intensity of the resulting electric field may be significantly weaker than in the case of neutral substances where energy has first to be invested in ionization.

The invention is further described in the following non-limiting examples. Example 1

An electric field driven emitter electrode of the kind shown in Figs. 4 and 5 was used. In the first experiment, the absorbent material filler 43 was soaked with a 5% alcoholic iodine solution (I₂) and in the second experiment, cypress essential oil (EO) was used. The emitter was connected to the positive terminal of a power supply, the open end was placed at a constant distance from a target, and the ion flux between the emitter electrode and the target surface was measured by means of a multimeter. The quantity of ions was calculated in approximation on the assumption that each ionic particle carries one elementary negative electric charge, i.e. the charge of one electron. Each substance was tested at three different distances of 1 cm, 2 cm and 3 cm, and at three constant voltages of 2 kV, 4 kV and 6 kV.

The results are plotted in Fig. 7 and it can be seen therefrom that at constant voltage, the quantities of ions increased with the decrease of the distance between the cathode and target surface and that at constant distance the amount of ions increased with the applied voltage. As seen, the maximum quantity of ions was observed at a distance of 1 cm with an applied voltage of 6 kV.

The quantities of the ions also depend on the nature of the substance and it can be seen from Fig. 7 that all being equal, the iodine solution produced more ions than the etheric oil which is accountable by the difference in the molecular weights and sizes of the tested molecules - the molecules of the etheric oil being significantly larger and heavier than those ofI₂.

Example 2

The penetration of iodine from a 5% alcoholic I₂ solution into an artificial membrane of 6% gelatin gel with 1.5% starch was examined at constant voltage of 2 kV and at the constant distance of 1 cm between the free end of the emitter rod and the artificial membrane. In three different experiments, the time for bombardment was 5, 10 and 20 min. and in each case the depth of penetration of I₂ into the membrane was examined by the detection of the color produced due to the iodine-starch reaction. The depth of penetration was tested by means of a molecular microscope having an x 40 resolution and the results are plotted in Fig. 8. As shown, the depth of penetration of iodine into the gel increased with time.

Example 3 Clinical Trial for the Treatment of Acne

A clinical trial was conducted at the Rivka Ziv Medical Center in Zefat, Israel to show the efficacy of the treatment of acne in accordance with the present invention.

The group of participants was composed of 9 women and 1 man. Their ages varied from 18 to 30 years old as follows:

Table 1

Participants were divided according to the status and grade of their pathology as follows: Table II

All participants underwent physical examination and laboratory test (c.b.c. and blood chemistry) prior to their enrollment in the trial. All were in good physical and mental health.

The treatment was carried out with an apparatus of the kind shown in Figs. 4 and 5 herein using a physiological solution containing 0.1% w/w of lavender oil and 0.1% w/w eucalyptus oil as useful substances. The distance between the emitter 44 and the skin was 1 cm. A voltage of 9,000 volts was applied and each cheek portion included within the funnel shaped spacer 45 was treated for 1 min. and the aggregate time of treatment of each cheek was 5 to 7.5 mins. The treatment was administered every 2-4 days, a total of 10 sessions for each participant. No side effects were observed or reported by the participants .

An improvement in the skin status was noted. Drying of the pastules, papules, decreased redness and disappearance of hyper pigmentation. The onset of the healing process began after 3-4 treatments.

At the end of the course of treatments 9 participants exhibited improvement which varied in degrees. In one participant no change was found (see Table III). Table HI

Participants Much improved - 2 Improved - 6 No change - 2

Example 4 In vitro Test of Bactericidal Effect on Staph. Epidermidis

The investigation was conducted in the following way: Bacterial population (strain Staph. Epidermidis) was grown on agar during 18 hours. The washing of bacterial population was diluted to a concentration of 10⁷ microbes per ml with sterile physiological solution. Petri dishes with Baird-Parker agar were inoculated with bacterial solution. Directly after the inoculation Petri dishes were treated by an apparatus of the kind shown in Figs. 4 and 5. After that treatment petri dishes were placed into an incubator for 24 hours at 37°C. At the next day dishes were checked and zone of sterilization (no growth) and zone of inhibition (slow growth) were measured. The antimicrobial activity of etheric oil solutions was shown and also the correlation of antimicrobial activity and parameters of electrostatic applicator, such as voltage, time of treatment and distance from electrode and treated surface. Series of experiments were conducted during the period 30.6.98-12.7.98 and the results are shown in Table IV.

All other conditions being equal, an increase of the voltage from 8 kV to 9 kV increases the effect of sterilization. It is also seen that effect of time of treatment is more significant than the change of distance to the treated substrate. It means that occasional change of distance during a treatment in the range of 0.5-1 cm is not critical. According to the results of the investigation, conditions such as 9 kV, 10 mins. treatment and 0.5-1 cm distance from the substrate may be recommended as optimal for sterilization of Staph. Epidermidis.

Table IV

Microbiological Test of Electrostatic Applicator

Claims

CLAIMS:

1. A method of topical administration of a useful substance to a subject for medical and cosmetic purposes, comprising placing at a distance from a target portion of the subject's body surface an electric field driven emitter electrode having a reservoir holding said useful substance and putting the said emitter electrode under the influence of an electric field having an intensity within the range of from 1,000 to 15,000 volts, whereby ionized molecular particles are emitted from said emitter electrode to bombard said target portion of the subject's body surface to produce a desired medical or cosmetic effect.

2. A method according to Claim 1, wherein the electric field driven emitter electrode is connected to an electric power source.

3. A method according to Claim 1, wherein the electric field driven emitter electrode is placed in an electric field created between an electric power source and said target portion of the subject's body surface.

4. The method according to any one of Claims 1 to 3, wherein the body surface serves as ground.

5. The method according to any one of Claims 1 to 3, wherein a second electrode is placed at some distance from the electric field driven emitter electrode, said emitter electrode is connected to an electric power source, and the electric field forms between the said emitter electrode and said second electrode.

6. A method according to any one of Claims 1 to 3, wherein a second electrode is placed at some distance from the electric field driven emitter electrode and the electric field forms between an electric power source and said second electrode.

7. For use in the topical administration of a useful substance to a subject for medical and cosmetic purposes, an electric field driven emitter electrode for use in bombarding a target portion of the subject's body surface with ionized molecular particles, comprising reservoir means for holding said useful substance, emitter means for the emission of ionized molecular particles of said useful substance, and optionally electrical terminal means for connection to an electric power source.

8. An electric field driven emitter electrode according to Claim 7, wherein said emitter means are in form of at least one capillary tube extending from said reservoir means.

9. An electric field driven emitter electrode according to Claim 7, wherein said emitter means are at least one rod extending from said reservoir means.

10. An electric field driven emitter electrode according to Claim 7, wherein said reservoir comprises absorber means capable of being soaked with a liquid material.

11. An electric field driven emitter electrode according to any one of Claims 7 to 10, wherein said reservoir means together with said emitter means are in form of a disposable cartridge.

12. An assembly for bombarding a target portion of a subject's body surface with ionized molecular particles of a useful substance for medical and cosmetic purposes, comprising an electric field driven emitter electrode as defined in any one of Claims 7 to 11 and spacer means having an open ended passageway for ionized molecular particles of said useful substance, which spacer means retain the electrode at a desired distance from the body surface.

13. An assembly according to Claim 12, comprising a second electrode.

14. An assembly according to Claim 13, wherein said second electrode is mounted within said open ended passageway in such a way as to leave free passage for said ionized molecular particles, whereby said ionized molecular particles can proceed beyond said second electrode.

15. An assembly according to Claim 14, wherein said spacer means is funnel shaped and said second electrode is annular.

16. An assembly according to Claim 14, wherein said spacer means is funnel shaped and said second electrode is a plate with at least one suitably located hole.

17. An assembly according to Claim 13, wherein said second electrode is a separate unit.

18. An assembly for bombarding a target portion of a subject's body surface with ionized molecular particles of a useful substance for medical and cosmetic purposes, comprising an electric field driven emitter electrode according to Claim 8 and spacer means for attachment to said emitter electrode, which spacer means comprise at least one tube for accommodation of said at least one capillary tube.