GB2518481A - Skin treatment devices and methods - Google Patents

Abstract

A radiofrequency (RF) skin treatment device delivers energy via electrodes 110 in a phase-controlled manner which heats skin volumes (92, figures 5A-5E) below the surface more than the skin surface (91) itself. At least one electrode at least partially encloses at least one other electrode, the electrodes preferably being concentric rings and a disc mounted in a single head 100. The outer electrodes 110B-110F may be of opposite polarity to the innermost electrode 110A in order to form a potential barrier (113, figure 5C) within the target skin volume. A specified transmission plan may be configured to keep the surface of the skin below a threshold temperature. The relative phase of the energy delivered to each electrode may be specified as part of the transmission plan. At least some of the electrodes may be linear or ellipsoidal (figure 5G).

Description

SKIN TREATMENT DEVICES AND METHODS

CROSS REFERENCE TO RELATED APPLICATIONS

100011 This application is a continuation in part of U.S. Patent Application No. 13/922,254, filed on June 20, 2013, which claims the benefit of U.S. Provisional Patent Application No. 61/665,552, filed on June 28, 2012, and also is a continuation in part of U.S. Patent Application No. 13/865,658, filed on April 18, 2013, which is a continuation of U.S. Patent Application No, 12/802,518, filed on June 7,2010, nowabandoned, which claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No, 61/213,409, filed June 5, 2009, and U.S. Provisional Patent Application No. 61/213,410, filed June 5, 2009. U.S. Patent Application No. 12/802,518 is also a continuation-in-part application of U.S. Patent Application No, 11/654,914, filed January 17, 2007, now U.S. Patent No. 8,206,381, which claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application No. 60/759,289, filed January 17, 2006, and U.S. Provisional Patent Application No. 60/774,167, filed February 17, 2006. Each such noted application is herein incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

1. TECHNICAL FIELD

100021 The present invention relates to the field of skin treatment, and more particularly, to radiofrequency (RF) skin treatment.

2. DTSCUSSION OF RELATED ART 100031 Energy emitting devices are typically used to heat cutaneous or subcutaneous tissues or to trigger a non-thermal chemical or photochemical reaction. in many cases, heating of the epidermis should be limited to prevent skin burns, This in turn limits the amount of energy that is delivered to deeper tissues, In a professional clinic setting, energy emitting skin treatment devices use skin cooling to prevent over heating of the epidermis. Due to the high cost and the size of a device which incorporates such functionality, active cooling is not practical in consumer, home-use devices, 100041 U.S. patent no. 8,206,381, which is incorporated herein by reference in its entirety, discloses an electrosurgical device for applying phase controlled RE energy to a treatment site.

s SUMMARY OF TIlE INVENTION

100051 One aspect of the present invention provides a skin treatment device comprising a plurality of electrodes applicable to a user's skin, wherein at least one of the electrodes at least partly encloses another at least one of the electrodes; at least one radio frequency (RF) generator, arranged to deliver RF energy to the skin via the electrodes; and a control unit arranged to control RF energy delivery by the at least one RF generator to the skin according to a specified transmission plan comprising controlling relative electrode polarities to concentrate the delivered RF energy to a specified skin volume below the skin surface.

100061 These, additional, and/or other aspects and/or advantages of the present invention are set forth in the detailed description which follows; possibly inferable from the detailed description; and/or learnable by practice of the present invention.

BRIEF DESCRIPTION OF THE DRAWTNGS

100071 For a better understanding of embodiments of the invention and to show how the same may be carried into effect, reference will now be made, purely by way of example, to the accompanying drawings in which like numerals designate corresponding elements or sections throughout.

100081 In the accompanying drawings: 100091 Figures 1A, lB and 2 are high level schematic perspective illustrations of skin treatment devices, according to some embodiments of the invention.

100101 Figures 3A, 3B, 4A and 4B schematically illustrate experimental results of applying skin treatment devices onto ge material that simulates the skin.

100111 Figures 5A-5G are high level schematic perspective illustrations of skin volume heating by controlling electrode polarities, according to some embodiments of the invention.

100121 Figure 6 is a high level schematic flowchart illustrating a skin treatment method, according to some embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

s 100131 Prior to the detailed description being set forth, it may be helpful to set forth definitions of certain terms that will be used hereinafter.

100141 The term "skin treatment" as used herein in this application refers to any type of skin treatment such as skin heating, treating wrinkles or rhytides, treating skin aging by collagen remodeling, treating diseases of the skin such as acne and psoriasis, treating skin roughness, treating skin pigmentation, skin peeling, epidermal skin rejuvenation, reducing hyperhydrosis, reducing acne or providing any other therapeutic or cosmetic effect.

100151 The temi "RF energy" as used herein in this application refers to radiofrequency electromagnetic energy delivered by the electrodes to the skin as a result of electromagnetic potentials applied to the skin through the electrodes and causing currents to flow through and heat regions of the skin.

100161 The term "phase" as used herein in this application refers to any value of the relative angle of a fluctuating current or voltage between electrodes which are driven from different RF sources. The terms "phase control" or "controlling the phase" of the delivered current or voltage, as used herein in this application, refer to setting a specific phase value to delivered current or voltage. The specific phase value may be any value from 0' to 360' (0 to 27t radians). The term "relative phase" between electrodes, as used herein in this application, refers to any phase difference between electrodes, including a zero phase difference.

100171 The term "polarity" as used herein in this application in relation to electrodes, refers to the electrode being a positive pole or a negative pole with respect to current delivery. The term "same polarity" as used herein in this application with reference to two electrodes, refers to the two electrodes having the same polarity during most of the time, i.e. the two electrodes being in the same polarity longer than they are in opposite polarities, or, using phase terms, have a phase difference between +90' and -90' (-m/2 to +x/2 radians). The signs + and -as used herein in this application to refer to electrode polarities schematically designate which elecodes have the same polarity, in the sense explained above. The phase between electrodes having the same sign may be zero but may also have any value between +90° and -90° (-ir/2 to +x/2 radians). Different s electrodes in the -I-or -groups may have different phase difference values between them.

Some or all of the electrodes in each of the + or -groups may have a zero phase difference between them.

100181 The term "potential barrier" as used herein in this application refers to an effect within the skin tissue volume of applying the same polarity as defined above to adjacent electrodes, As both adjacent electrodes induce similar charges into adjacent skin volumes, each of the charged skin volumes repels currents having a similar polarity from entering the skin volumes. Without wishing to be bound by theory, the repulsion effect of the potential barrier is used in the current invention to drive currents deeper into the skin volume and to control the depth through which currents flow. Potential barriers are schematically illustrated in Figures 5A-SE.

100191 With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention, In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

100201 Before at least one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is applicable to other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

100211 Radiofrequency (RF) skin treatment devices and methods are provided herein. RF energy is delivered via concentric electrodes in a phase-controlled manner which heats S skin volumes below the surface more than the skin surface itself The combination of controlling the phases of the RF energy delivered to different electrodes and the concentric configuration of the electrodes allows concentrating the delivered energy in specific regions below the skin surface at a particularly high efficiency. Configurations of the concentric electrodes, their forms and combinations with other electrodes and the phase polarities applied to the electrodes are also provided.

100221 Figures IA, lB and 2 are high level schematic perspective illustrations of skin treatment devices 100 according to some embodiments of the invention. Figures IA and lB schematically illustrate device 100 connected via a cable 99 to a central unit, while Figure 2 schematically illustrates device 100 as an independent unit having a power source (not shown) within a housing 101.

100231 Skin treatment device 100 comprises a plurality of concentrically arranged electrodes 110 applicable to a user's skin, a radio frequency (RF) generator (not shown), arranged to deliver RF energy to the skin via electrodes 110; and a control unit (not shown) arranged to control RF energy delivery by the RF generator to the skin according to a specified transmission plan comprising controlling relative electrode polarities to concentrate the delivered RF energy to a specified skin volume below the skin surface.

The specified transmission plan may be configured to keep a surface of the skin below a specified temperature threshold and/or to elevate a temperature of a specified skin volume below the surface of the skin (the elevated temperature being with respect to the surface of the skin).

100241 Skin treatment device 100 comprises at least one of electrodes 110 at least partly encloses another at least one of electrodes itO, In certain embodiments, some electrodes may be concentric, some electrodes may be eccentric with relation to each other, The degree to which certain electrodes 110 enclose other electrodes 110 may be varied according to the required fomi of potential barriers within the skin, required heating

depth and other specifications of device 100.

100251 Electrodes 110 may be round and an innermost electrode I1OA may be a disc.

Electrodes 110 may be equally spaced or electrode groups may be defined by larger s spaces between some of electrodes 110. For example, Electrodes 110 may comprise an inner electrode group (e.g., 1IOA, IIOB and hOC in Figure IA) which is interspaced from an outer electrode group (e.g., hOD, 1IOF and IIOF in Figures hA). Figure lB schematically illustrates the following dimensional parameters of illustrated exemplary device 100. Electrodes 1 bA-I IOF are characterizes, respectively, by widths EA, EB, Ec, ED, EE and EF and radii RA, RB, Rc, RD. RE and R (innermost disc-shaped electrode II OA is characterized by EARA), and are interspaced by spaces of widths SA, SB, S, SD and SE. Tn the illustrated non-limiting case, inner group of electrodes IJOA-C is separated from outer group of electrodes hOD-F by space 5c of a larger width than the other inter-electrode spaces. R103 denotes the radius of a face 105 of the applicator head, which clearly may have a shape other than circular as well and may at least partially be disposable.

100261 Without wishing to be bound by theory, the spatial configuration and the phase configuration of electrodes 110 are understood to determine the heating pattern of the treated skin for given skin characteristics, Tn particular, as larger electric currents tend to flow through regions of lower impedance, controlling the phase and the polarity of electrodes 110 allows controlling the extent of tissue heating. For example, each of two adjacent electrodes having the same polarity (i.e., electrodes that are substantially in phase with each other) increases the impedance the other electrode experiences at the tissue region between the electrodes. Hence, pairs of electrodes with the same polarity create electrical potential barriers 113 (see Figures SA-5E below) with increased impedance between the electrodes, Barriers 113 tend to drive the electric currents associated with the pair of electrodes deeper into the skin tissue (e.g,, at an angle to the skin surface), as the increased impedance is experienced closer to the electrodes and hence closer to the surface, The specified transmission plan may be configured to assign electrode polarities to generate potential barrier 113 that drives the delivered RF energy to a specified skin volume below the surface of the skin.

100271 Relative electrode polarities are controlled to deliver the RF energy preferentially below the surface of the skin, thus heating a skin volume below the surface to a greater S extent than the skin surface is heated. The inventors have found out that using at least one electrode 110 that at least partly encloses at least one other electrode 110 intensifies the effect of the phase controlled energy delivery in the sense that more energy is delivered to the skin volume below the surface and less energy is delivered to the skin surface.

Without being bound by theory, the inventors believe that the enclosing configuration of the electrodes prevents or reduces lateral (i.e., horizontal on the skin surface) RF energy delivery from electrodes 110, and hence reduces significantly surface heating. Instead, more RF energy is delivered vertically or at an angle below the surface and thus a larger portion of the delivered energy actually heats up the specified skin volume below the surface of the skin. A most symmetric configuration is of concentric electrodes 110. Such a configuration may maximize the current concentration effect. However, the present invention is not limited to configurations with concentric electrodes and comprises partially concentric, eccentric, and varying degrees of enclosing by electrodes 110. Any of enclosing electrodes 110 and enclosed electrodes 110 may have different forms, such as round, circular, elliptic, partially circular, linear etc. 100281 The relative electrode polarities may be determined according to specific purposes, requirements and configurations, and may be changed dynamically, For example, the relative electrode polarities may be controlled to yield one innermost electrode 11 OA with a reversed polarity with respect to outer electrodes 11 OB-F. Tn another example, the relative electrode polarities may be controlled to yield an inner electrode group (e.g., 11OA, 11OB and hOC in Figure 1A) with a reversed polarity with respect to an outer electrode group (e.g., lion, hOE and 11OF in Figures 1A). While the figures illustrate six electrodes, similar concentric configurations may be designed with any number of electrodes 110, in non-limiting examples, four or eight, but also larger numbers and odd numbers.

100291 Housing 101 of device 100 may be arranged to hold electrodes 110 and electronic circuitry for operating electrodes 110. Housing 101 may be ergonomically designed, for example to apply the treatment in a paintbrush-like continuous manner. Housing 101 may comprise a mechanism that assures contact of electrodes 110 with the skin. Device 100 s may be operated by pressing a button 102. Device 100 may be arranged to operate at different intensities by pressing button 102 at different patterns (repeatedly, continuously, etc.). The RF generator or generators may be external and connected via cable 99 or be internal in housing 101. Power supply may be inductive, The RF generator may be regulated by a RF voltage regulator and controlled by the control unit such as a micro controller, as described in detail in the parent applications. The control unit may be associated with a trigger and a low voltage regulator. The control unit may be further arranged to control the phase of each electrode 1 bA-F' and to coordinate the polarities of the electrodes. Hence, the control unit may be arranged to set any specified phase between any two electrodes 110 to exactly control energy delivery to the skin. In particular, the control unit may designate reversed polarities to subgroups of electrodes 110. The reversed polarities may be approximate (i.e., not necessarily 180' but also, e.g., 120' or 160', etc.) as explained above. The phase differences between electrodes 110 may be pre-determined and could be controlled during operation or be maintained constant at a predefined phase. The transmission plan may comprise controlling relative electrode polarities to concentrate the delivered RF energy to a specified skin volume. For example, the relative electrode polarities may be controlled to yield one or two pairs of adjacent electrodes 110 with substantially the same polarity. The control unit may be arranged to control the relative electrode polarities of the at least one partly enclosing electrode and of the at least one partly enclosed electrode to form a potential barrier around the latter within the specified skin volume.

100301 Electrodes 11OA-11OF may all be connected via a transformer to a single generator or several generators may be used to supply the RF energy to electrodes 110.

Paired electrode configurations (having the electrodes connected to both poles of the generator may be practical in home use devices to reduce the number of generators, while because commercial devices for use in professional clinic settings may have multiple grounded generators, each providing a single electrode. Some of electrodes 11OA-11OF may be connected together to improve current delivery and heating. Thus devices 100 having a specified number of generators may be used to deliver RF energy via a larger number of electrodes by interconnecting some of the electrodes to single generators.

s 100311 In certain embodiments, the control unit may be further arranged to derive a realtime estimation of skin impedance and adjust the delivered energy according to the estimated skin impedance, resulting in more predictable results, The skin impedance estimation may be derived from measuring energy delivery with respect to applied voltage (skin impedance increases with the treated skin volume). Different energy delivery parameters may be applied to treating different skin region (e.g., in the face, the eye region is characterized by thin skin in the range of 1mm, while the cheek region is characterized by thin skin in the range of 3-4mm).

100321 In certain embodiments, skin treatment with device 100 may be combined with any other treatment method, e.g. light or ultrasound delivery, application of gels, creams, topical formulations etc. 100331 Certain embodiments may comprise central disc-shaped electrodes 11OA having a diameter (2RA) between 4mm and 12mm and circular electrodes 11OB-F each having a width (Es, Ec, ED, ED and EF) between 1 mm and 3 mm, Adjacent electrodes may be spaced (SA, SB, 5C, SD and SE) between 1 mm and 3 mm apart, and electrode groups may be interspaced between 3mm and 6mm apart (Sc in the example illustrated in Figure 1B).

Thus, electrode radii may span a range between 1-4 mm for innermost electrode IIOA (RA) to 80mm for outermost electrode I IOF (RF), other electrodes I IOB-E having intermediate radii, Tn certain embodiments, the areas of electrodes II OA-F may range 2 2.

between 0.1 mm and 10cm, depending on the selected widths and radii.

100341 In certain embodiments, skin treatment device 100 may comprise at least one of electrodes 110 which is made of plastic (e.g., polycarbonate plastic) coated by a conductive coating. At least a part of device 100, e.g., at least part of face 105 of the applicator head containing at least one of electrodes 110, may be configured to be detachable and disposable. Face 105 of device 100 which hold electrodes 110 may be flat or slightly curved and may comprise surface features.

100351 Figures 3A, 3B, 4A and 4B schematically illustrate experimental results of applying skin treatment device onto gel material that simulates the skin. Figures 3A and 4A illustrate application of RF devices having linearly arranged electrodes (similar to devices described in the parent applications, while Figures 3B and 4B illustrate devices s 100, according to some embodiments of the invention. The illustrations are tracings of lines 71-74 and 81-84 respectively, which mark regions with equal temperature, upon application of skin treatment devices. Figures 3A and 3B illustrate a case of a dynamic treatment in which the respective device is moved during treatment, while Figures 4A and 4B illustrate a case of a static treatment in which the respective device is not moved during the treatment. In all four figures the devices applied a power of 40 Watts.

100361 In Figures 3A and 3B, lines 71, 72, 73 and 74 mark temperatures of approximately 35°C, 31°C, 26°C and 2 1°C, respectively, for dynamic device application for four minutes. The depths Di and D2 denote, respectively, the depth in the material over which a temperature difference of 15°C was created. While the prior art device with linearly arranged electrodes yielded D1=3.65 mm, device 100 with concentric electrodes yielded D2=8.80 mm, i.e., a more effective heating below the skin's surface, Figures 3A and 3B also illustrate that the skin surface is above the temperature line of 26°C, i.e., the temperature of the skin volume below the surface is &evated with respect to the temperature of the skin surface by over 9°C. Due to the dynamic application the heated skin volume below the surface has a much larger horizontal extent than vertical extent.

In Figures 4A and 4B, lines 81, 82, 83 and 84 mark temperatures of approximately 44°C, 35°C, 31°C and 26°C, respectively, for static device application for half a minute, The static application allows temperature differences to build up, and thus temperatures are higher and heated regions are larger. It is noted that actual application on the skin is recommended to be dynamic, and the illustrated static application is presented mainly for illustrative purposes. in the illustrated example, heating depths D3, D4 are similar in the prior art device and in device 100 (Figures 4A and 4B respectively), namely ca. 10 mm for a 25°C temperature difference, ca. 12 mm for a 20°C temperature difference and ca. 14mm for a 15°C temperature difference, However, device 100 provides a larger and more uniform heated volume than the prior art device as seen in the extent of the region with temperature larger than 44°C (device 100 in Figure 4B heats about double the volume heated by the prior art device illustrated in Figure 4A) and in the 35°C, 31°C and 26°C, which are strongly curved using the linearly arranged elecftodes (Figure 4A) but smooth and gradual using device 100 (Figure 4B).

s 100381 Figures SA-SE are high level schematic perspective illustrations of skin volume heating by controlling electrode polarities, according to some embodiments of the invention. Electrode configurations which are illustrated in Figures Sit-SC are non-limiting examples, and other electrode configurations, derived from the principles described below are likewise within the scope of the invention. Figures Sit-SC schematically illustrate face 105 of the applicator head of device 100 which hold electrodes 110, placed upon a user's skin 90. The head is applied onto surface 91 of skin and produces a heating of skin tissue volume 92 below surface 91, Device 100 is configured, through the configuration of the phase polarities of different electrodes 110, to heat skin volume 92 and elevate its temperature beyond the temperature of skin surface 91.

100391 Figures SA and SB schematically illustrate device 100 having innermost disc-shaped electrodes 1IOA aiid ring-shaped electrodes 1IOB-F (similar to Figure IA), concentrically arranged with respect to innermost electrode 110k Figures 5A and SB, as well as Figures SC-SE below, further illustrate schematically electrode polarities by "+" and "-" signs, denoting that the respective electrodes are allocated reverse polarities. It is noted that the term "reverse polarities" refers to electrodes having differing polarities during most of the time, i.e., having reversed phase polarities longer than they have similar polarities, or, using phase terms, having a phase difference larger than +90' or smaller than -90° (>+ir/2 or < -m/2 radians). Different electrodes in the "+" or "-" groups may have different phase difference values between them (but within -m/2 to +ir/2 within each group). Some or all of the electrodes in each polarity group may have a zero phase difference between them.

100401 Finally, Figures SA-SE schematically illustrate resulting currents 111 within skin volume 92. While varying the specific electrode configuration changes the specific current patterns within skin 90, devices 100 are arranged to configure electrode polarities to form at least one barrier 113 which drives currents 111 deeper than skin surface 91 and into skin tissue volume 92. Any of electrodes 110A-11OF as well as resulting barriers 113 may be circular, semi-circular or circular with missing sectors. Without being bound by theory, any of electrodes 110B-11OF may be shaped to shield inner electrodes from s receiving surface currents from external electrodes having a reversed polarity, thus forcing currents 111 to penetrate skin volume 92 below skin surface 91.

[004fl Figure SA schematically illustrates an inner group of electrodes IIOA-IIOC which has a reversed polarity with respect to an outer group of electrodes hOD-I lOP (see Figure IA for full electrode reference numerals). Tn this case, barrier 113 is formed as a cylindrical skin volume below the space that separates the inner group from the outer group. As barrier 113 is circular, no surface current is allowed to flow between inner group electrodes 1IOA-I bc and outer group electrodes t bOB-I lOP. Thus, more current flows into the depth of the skin tissue, resulting in a larger temperature difference between skin volume 92 below the surface and skin surface 91 itself.

100421 Figure SB schematically illustrates innermost electrodes 11OA which has a reversed polarity with respect to the other electrodes 11OB-IIOF. In this case, barrier 113 is formed as a cylindrical skin volume below the space that separates innermost electrode IIOA from other electrodes IIOB-I1OF (see Figure IA for full electrode reference numerals). As barrier 113 is circular, no surface current is allowed to flow between innermost electrode I IOA and outer electrodes I lOB-I lOP, Thus, more current flows into the depth of the skin tissue, resulting in a larger temperature difference between skin volume 92 below the surface and skin surface 91 itself. The inventors have found out in this case that heating power is increased by ca. 30% with respect to linearly arranged linear electrodes with controlled phase transmission. Certain embodiments enable using 85-90% of the delivered energy to heat skin volume 92 below skin surface 91 with little of the delivered energy heating skin surface 91. Certain embodiments comprise a bipolar arrangement of electrodes 110, in which electrodes 110 are arranged in pairs of reversed polarities, which is configured to heat skin surface 91. Device may allow switching between a phase-controlled mode and a bipolar mode of operation, 100431 Figure 5C schematically illustrates device 100 having inner disc-shaped electrode 11OA, outer ring-shaped electrode 11OF, concentrically arranged with respect to inner electrode IWA, as well as adjacent linear electrodes 109. Clearly, several concentric electrodes 110 may be positioned between inner and outer electrodes 11OA, 11OF, S respectively, and linear electrodes 109 may vary in number and be positioned at different locations around outer electrode IIOF, As illustrates schematically in Figure SC, outer electrode IIOF shields inner electrode 1IOA from linear electrodes 109 and forms potential barrier 113 within skin volume 92 which drives currents lii into the depth of the skin tissue, heating hence skin volume 92 more than skin surface 9!.

100441 Figure SD schematically illustrates device 100 having inner disc-shaped electrode I bA, outer ring-shaped electrode I IOF, concentrically arranged with respect to inner electrode I bA, as well as adjacent linear electrodes 109 at either side of outer electrode 110F. Clearly, several concentric electrodes 110 may be positioned between inner and outer electrodes 1IOA, 11OF, respectively, and linear electrodes 109 may vary in number and be positioned at different locations around outer electrode 11OF. As illustrates schematically in Figure SD, outer electrode 11OF shields inner electrode IIOA from linear electrodes 109 on either side thereof, and forms potential barrier 113 within skin volume 92 which drives currents 111 into the depth of the skin tissue, heating hence skin volume 92 more than skin surface 9!.

100451 Figure SE schematically illustrates device 100 having inner disc-shaped electrode 11 OA, outer electrode 11 OF, concentrically arranged with respect to inner electrode IIOA, as well as adjacent linear electrodes 109. Outer electrode IIOF may be a semi-circle, or be shaped as a ring which lacks a sector, to shield inner electrode I1OA from linear electrodes 109 in their respective direction. The missing sector of outer electrode 109 may not reduce the strength of barrier 113 significantly, as no electrodes of reversed polarity (with respect to innermost elecnode 11OA) are positioned near the missing sector. Clearly, several concentric electrodes 110 may be positioned between inner and outer electrodes IIOA, hOP, respectively, and linear electrodes 109 may vary in number and be positioned at different locations around outer electrode 11OF. As illustrates schematically in Figure SD, outer electrode 1101? shields inner electrode IIOA from linear electrodes 109 and forms potential barrier 113 within skin volume 92 which drives currents 111 into the depth of the skin tissue, heating hence skin volume 92 more than skin surface 91.

100461 Skin treatment device 100 may hence comprise a plurality of electrodes 110 S applicable to user's skin 90, wherein at least two of electrodes 110 are concentric. At least one of electrodes 110 may be linear (indicated as linear electrodes 109), at least one of electrodes 110 may be ring-shaped and/or at least one of electrodes 110 may be shaped as a ring that lacks a sector. All or some of electrodes 110 may be concentric and/or the at least two concentric electrodes may be round.

100471 Figures SF and SG schematically illustrate additional electrode configuration principles, according to some embodiments of the invention. Figure SF' schematically illustrates concentric electrodes I tOE, I IOF enclosing, in an eccentric manner, concentric electrodes 11OA, 11OB. Any relative positioning of electrodes 110 may be designed to achieve required heating effects. Figure SG schematically illustrates a combination of electrodes including outer elliptic electrode 1IOF enclosing innermost linear electrode IIOA which is perpendicularly positioned with respect to outer linear electrode 109, Elements from the configuration illustrated in Figure 5G may be applied to any of the other illustrated configurations, for example elliptic electrodes, linear electrode at different angles and linear innermost electrodes.

100481 Any of the electrode configurations describes above may be modified according to other configurations, e.g., any of electrodes 110 may be positioned eccentrically or be made to partly enclose inner electrodes 110, as illustrated in Figure SE, all with respect to specific requirements.

100491 The configurations presented above are non-limiting examples for configurations with four and six electrodes. They are not to be taken as limiting the number of electrodes but as indicating plausible configurations of larger numbers of electrodes.

100501 In embodiments, the control unit may be further arranged to derive a realtime estimation of skin impedance and adjust the delivered energy according to the estimated skin impedance, resulting in more predictable results, The skin impedance estimation may be derived from measuring energy delivery with respect to applied voltage (skin impedance increases with the treated sian volume). Different energy deliveiy parameters may be applied to treating different sian region (e.g., in the face, the eye region is characterized by thin skin in the range of 1 mm, while the cheek region is characterized by thin skin in the range of 3-4 mm).

s 100511 Figure 6 is a high level schematic flowchart illustrating methods 200 according to some embodiments of the invention. Methods 200 comprise methods of configuring RF skin treatment applicator heads and skin treatment methods.

100521 Method 200 may comprise delivering RF energy via electrodes to the skin according a specified transmission plan (stage 210), arranging the electrodes concentrically (stage 220) and controlling relative electrode polarities to concentrate the delivered RF energy to a specified skin volume (stage 215).

100531 Method 200 may comprise designing the transmission plan to maximize the RF energy delivery below a subgroup of the electrodes (stage 212) and/or elevating the temperature of a skin volume below the surface with respect to the skin surface (stage 216) and/or keeping a surface of the skin below a specified temperature threshold (stage 218). In certain embodiments, method 200 may comprise configuring at least one electrode to at least partly enclose another electrode (stage 219).

100541 Method 200 may comprise configuring at least two of the electrodes to be concentric (stage 222), configuring the electrodes to be round (stage 230), configuring at least one of the electrodes to be linear (stage 214), using at least one electrode which is shaped as a ring that lacks a sector (stage 232) and/or using an innermost disc-shaped electrode (stage 235).

100551 Method 200 may comprise applying reverse polarities to the innermost electrode with respect to outer electrodes (stage 240) or applying reverse polarities to an inner group of electrodes with respect to an outer group of electrodes (stage 245). Method 200 may comprise assigning electrode polarities to generate a potential barrier that drives current to skin volume below the skin surface (stage 247). Method 200 may comprise enclosing at least one electrode by another electrode which is supplied with a reversed polarity to generate the potential barrier (stage 248). Method 200 may further comprise interspacing the inner and outer electrode groups with reverse polarity (stage 249).

100561 Method 200 may comprise using plastic electrodes covered by a conductive coating (stage 250) and/or configuring at least part of the applicator head to be disposable (stage 252).

100571 In the above description, an embodiment is an example or implementation of the S invention. The various appearances of "one embodiment", "an embodiment" or "some embodiments" do not necessarily all refer to the same embodiments, 100581 Although various features of the invention may be described in the context of a single embodiment, the features may also be provided separately or in any suitable combination. Conversely, although the invention may be described herein in the context of separate embodiments for clarity, the invention may also be implemented in a single embodiment.

100591 Embodiments of the invention may include features from different embodiments disclosed above, and embodiments may incorporate elements from other embodiments disclosed above. The disclosure of elements of the invention in the context of a specific embodiment is not to be taken as limiting their used in the specific embodiment alone.

100601 Furthermore, it is to be understood that the invention can be carried out or practiced in various ways and that the invention can be implemented in embodiments other than the ones outlined in the description above.

100611 The invention is not limited to those diagrams or to the corresponding descriptions. For example, flow need not move through each illustrated box or state, or in exactly the same order as illustrated and described, 100621 Meanings of technical and scientific terms used herein are to be commonly understood as by one of ordinary skill in the art to which the invention belongs, unless otherwise defined.

100631 While the invention has been described with respect to a limited number of embodiments, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of some of the preferred embodiments, Other possible variations, modifications, and applications are also within the scope of the invention.

Accordingly, the scope of the invention should not be limited by what has thus far been described, but by the appended claims and their legal equivalents.

Claims (20)

1. CLAIMS1. A skin treatment device comprising: a plurality of electrodes applicable to a user's skin, wherein at least one of the electrodes at least partly encloses another at least one of the electrodes; S at least one radio frequency (RF) generator, arranged to deliver RF energy to the skin via the electrodes; and a control unit arranged to control RF energy delivery by the at least one RF generator to the skin according to a specified transmission plan comprising controlling relative electrode polarities to concentrate the delivered RF energy to a specified skin volume below the skin surface.
2. 2. The skin treatment device of claim I, wherein the control unit is arranged to control the relative electrode polarities of the at least one partly enclosing electrode and of the at least one partly enclosed electrode to form a potential barrier around the latter within the specified skin volume.
3. 3. The skin treatment device of claim 1 or claim 2, wherein at least one of the electrodes is at least one of linear, ring-shaped or shaped as a ring that lacks a sector.
4. 4. The skin treatment device of claim 1, 2 or 3, wherein the relative electrode polarities are controlled to yield one electrode with a reversed polarity with respect to the other electrodes; or to yield one innermost electrode with a reversed polarity with respect to at least one outer electrode.
5. 5, The skin treatment device of claim 1, 2 or 3, wherein the relative electrode polarities are controlled to yield one electrode group with a reversed polarity with respect to another electrode group; or to yield an inner electrode group of electrodes with a reversed polarity with respect to an outer electrode group of electrodes, wherein each of the inner and outer groups comprises at least one electrode.
6. 6. The skin treatment device of any preceding claim, wherein the electrodes comprise an inner electrode group which is interspaced from an outer electrode group, wherein each of the inner and outer groups comprises at least one electrode.
7. 7. The skin treatment device of any preceding claim, wherein at least two or all of the electrodes are concentric and round, and an innermost electrode is a disc.
8. 8. The sian treatment device of any preceding claim, wherein the specified transmission plan is configured to keep a surface of the skin below a specified temperature threshold.
9. 9. The skin treatment device of any preceding claim, wherein the specified S transmission plan is configured to elevate a temperature of a specified skin volume below the surface of the skin, the elevated temperature being with respect to the surface of the skin,
10. 10. The skin treatment device of any preceding claim, wherein the specified transmission plan is configured to assign electrode polarities to generate a potential barrier that drives the delivered RF energy to a specified skin volume below the surface of the skin.
11. 1 I. The skin treatment device of any preceding claim, wherein at least one of the electrodes is made of plastic coated by a conductive coating.
12. 12. The skin treathmnt device of any preceding claim, wherein at least a part of the device, containing at least one of the electrodes, is configured to be disposable.
13. 13. A method of configuring an RF sian treatment applicator head, the method comprising arranging at least one electrode to at least partly enclose another electrode on the head.
14. 14. The method of claim 13, further comprising arranging at least two or all electrodes to be concentric.
15. 15. The method of claim 13 or 14, further comprising arranging at least two electrodes into ai inner group and an outer group, wherein each of the inner and outer groups comprises at least one electrode,
16. 16. The method of claim 15, further comprising configuring at least one of the electrodes to be at east one of: disc-shaped, round, circular, and shaped as a ring that lacks a sector.
17. 17. A skin treatment method comprising: configuring a plurality of electrodes to comprise at east one of the electrodes at least partly enclosing another at least one of the electrodes, and delivering RF energy via the plurality of electrodes to a user's skin according to a specified transmission plan, the specified transmission plan comprising controlling relative electrode polarities to concentrate the delivered RF energy to a specified skin volume.
18. 1 8. The skin treatment method of claim 1 7, further comprising configuring the specified transmission plan to keep a surface of the skin below a specified temperature threshold and elevating, by the delivered RF energy, a temperature of the specified skin volume below the surface with respect to the skin surface.
19. 19. The skin treatment method of claim 17 or 18, further comprising applying reverse polarities to at least an innermost electrode with respect to at least one other electrode.
20. 20. The skin treatment method of claim 17,18 or 19, further comprising controlling relative electrode polarities of the at least one partly enclosing electrode and of the at least one partly enclosed electrode to form a potential barrier around the later within the specified skin volume.