METHOD AND SYSTEM FOR INVASIVE SKIN TREATMENT
A system and method for simultaneously heating a plurality of discrete skin volumes to a coagulation temperature. The system comprises an applicator containing an electrode having a plurality of spaced apart protruding conducting elements configured to contact the skin surface at a plurality of discrete locations. A controller applies a voltage to the electrode so as to simultaneously heat a plurality of skin volumes to a coagulation temperature when the applicator is applied to the skin surface.
This application is being filed under 35 USC 111 and is a continuation of and claims the benefit of the filing date of U.S. patent application Ser. No. 10/931,271 that was filed on Sep. 1, 2004 and bears the title of METHOD AND SYSTEM FOR INVASIVE SKIN TREATMENT.
FIELD OF THE INVENTIONThe invention relates to methods and systems for skin treatment.
BACKGROUND OF THE INVENTIONDirected damage of the skin is used to stimulate regrowth of collagen and to improve skin appearance. A well known method of directed damage is ablating the epidermis using laser radiation having wavelengths strongly absorbed by water so as to heat the water to above boiling temperature. Typical lasers used for epidermis ablation are CO2 and Er:YAG lasers. Ablating the epidermis using RF (radiofrequency) current is described in U.S. Pat. No. 6,309,387. This treatment significantly reduces wrinkles and improves the skin appearance. The main disadvantages of skin resurfacing are the long healing period that can be over a month long and the high risk of dischromia. These disadvantages have reduced the popularity of ablative skin resurfacing in recent years.
Non-ablative skin resurfacing is based on heating of the dermis to a sub-necrotic temperature with simultaneous cooling of the skin surface. U.S. Pat. No. 5,810,801 describes penetrating the dermis with infrared laser radiation with dynamic cooling of the skin surface using a cryogen spray.
Wrinkles are created in skin due to the breakage of collagen fibers and to the penetration of fat into the dermal structure. Thus, destroying adipose cells and structure, can improve the surface structure. However, most wrinkle treatment methods target the collagen and do not have a significant effect on deep wrinkles. Radio frequency (RF) energy has been used for the treatment of the epidermal and dermal layers of the skin. For example, U.S. Pat. No. 6,749,626 describes use of RF for collagen formation in dermis. This patent describes a method for collagen scar formation. U.S. Pat. Nos. 6,470,216, 6,438,424, 6,430,446, and 6,461,378 disclose methods and apparatuses for affecting the collagen matrix using RF with special electrode structures together with cooling and smoothing of the skin surface. U.S. Pat. Nos. 6,453,202, 6,405,090, 6,381,497, 6,311,090, 5,871,524, and 6,452,912 describe methods and apparatuses for delivering RF energy to the skin using a membrane structure. U.S. Pat. Nos. 6,453,202 and 6,425,912 describe methods and apparatuses for delivering RF energy and creating a reverse temperature gradient on the skin surface. Although a non-ablative treatment is much safer and does not scar the skin tissue, the results of non-ablative treatments are less satisfactory.
A method described in US Patent Application No. 20030216719 attempts to maintain the efficiency of ablative treatment with a shorter healing time and a lower risk of adverse effects. The device described in that patent coagulates discrete regions of the skin where the regions have a diameter of tens of micrometers and the distance between the regions is larger than the regions themselves. This treatment provides skin healing within a few days but the results are very superficial and less spectacular than with CO2 laser treatment, even after multiple treatments.
U.S. Pat. No. 6,277,116 describes a method of applying electromagnetic energy to the skin through an array of electrodes and delivery electrolyte using a microporous pad.
A device for ablation of the skin stratum corneum using RF electrodes is described in U.S. Pat. Nos. 6,711,435, 6,708,060, 6,611,706, and 6,597,946. However, the parameters of this device are optimized for the ablation of the stratum corneum so as to enhance drug penetration into the skin, and not for thermal collagen remodeling.
SUMMARY OF THE INVENTIONThe present invention provides a system and method for simultaneously heating skin at a plurality of discrete regions of the skin. The invention may be used for collagen remodeling. In accordance with the invention RF energy is applied to the skin at a plurality of discrete locations on the skin. The RF energy is applied using an electrode having a plurality of spaced apart protruding conducting pins. When the electrode is applied to the skin surface, each protruding conducting pin contacts the skin surface at a different location, so that the plurality of pins contacts the skin at a plurality of discrete locations. An RF voltage is then applied to the electrode so as to generate an electric current in the skin that heats the skin to a coagulation temperature simultaneously at a plurality of discrete regions of the skin. Coagulation temperatures are typically in the range of about 60° C. to about 70° C.
The protruding pins may have blunt tips which do not penetrate into the skin when the electrode is applied to the skin. In this case, the discrete regions of treated skin are located at the skin surface in the epidermis. Alternatively, the pins may have sharp tips that allow the protruding pin to penetrate the skin into the dermis. In this way, the discrete regions of treated skin are located in the dermis.
In another embodiment, the protruding elements are provided with sharp tips that allow the elements to penetrate into the skin. After application of the RF current in the skin, the protruding elements are pressed into the skin and an electrical current is then generated that coagulates tissue in the vicinity of the tip of each protruding element. The mechanical properties of the skin are changed after coagulation and the protruding elements may penetrate inside the skin without excessive pressure. A pre-pulse of RF energy can be applied to the skin in order to soften the skin tissue so as to facilitate penetration of the protruding elements into the skin.
The surface of the skin may be pre-cooled and/or cooled during the treatment to avoid damage to the skin in the area between protruding elements. Skin cooling may be provided by contact cooling or by applying a pre-cooled liquid or cryogen spray.
The invention may be used in wrinkle treatment, collagen remodeling, skin tightening, loose skin treatment, sub-cutaneous fat treatment or skin resurfacing.
Thus in its first aspect, the invention provides a system for simultaneously heating a plurality of discrete skin volumes to a coagulation temperature, comprising:
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- (a) an applicator comprising an electrode having a plurality of spaced apart protruding conducting elements configured to contact the skin surface at a plurality of discrete locations; and
- (b) a controller configured to apply a voltage to the electrode so as to simultaneously heat a plurality of skin volumes to a coagulation temperature when the applicator is applied to the skin surface.
In its second aspect, the invention provides a method for simultaneously heating a plurality of discrete skin volumes to a coagulation temperature, comprising:
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- (a) applying an applicator to the skin surface, the applicator comprising an electrode having a plurality of spaced apart protruding conducting elements configured to contact the skin surface at a plurality of discrete locations; and
- (b) applying a voltage to the electrode so as to simultaneously heat a plurality of skin volumes to a coagulation temperature.
In the case when protruding part of the electrode penetrates within the skin the size of protruding elements should be small enough to avoid significant damage of the skin surface. Preferable size of protruding elements is from 10 to 200 microns and coagulation depth can be varied from 100 microns up to 2 mm for invasive electrodes.
In order to understand the invention and to see how it may be carried out in practice, preferred embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:
The present invention can be combined with other methods of skin treatment including laser treatment. For example non-ablative collagen remodeling by laser radiation may be combined with the invasive RF heating of the skin dermis in accordance with the invention.
The preferable parameters for non-invasive skin coagulation in accordance with the invention are as follows:
Electrode size above 0.3 cm;
Protruding element at contact with the skin up to 0.5 mm
Protruding element height about 1 mm.
Distance between protruding elements at least twice the element diameter;
Current density: over 1 A/cm2;
RF current pulse duration: not longer than 0.5 sec;
The optimal parameters for invasive skin coagulation:
Electrode size above 0.3 cm;
Pin diameter at contact with the skin not larger than 0.3 mm
Pin protruding height above 1 mm.
Distance between pins at least 1 mm;
Current density above 0.1 A/cm2;
RF current pulse duration not longer than 0.5 sec;
Claims
1. A skin treatment apparatus for selectively treating volumes of skin tissue comprising:
- an applicator including an electrode from which a plurality of protruding sharp needle type elements configured to penetrate a surface of a target area of skin extend;
- a radio frequency energy generator operably connected to the plurality of needle type elements such that the elements could be energized;
- wherein the needle type elements are arranged so as to treat discrete volumes of tissue such that for selected treatment parameters tissue is spared around the treated volumes.
2. The skin treatment apparatus according to claim 1 wherein said electrode with the plurality of protruding needle type elements is mechanically connected to the applicator body.
3. The apparatus according to claim 1, wherein the protruding needle type elements are made of an electrically conductive material.
4. The skin treatment apparatus according to claim 1 wherein a portion of sides of each of the protruding needle type elements is coated with insulating material to avoid skin heating along the coated portion of the needle type elements.
5. The skin treatment apparatus according to claim 1 wherein the protruding conducting elements are operatively configured to penetrate through epidermis into dermis and apply RF energy to one or more volumes completely located in the dermis.
6. The skin treatment apparatus according to claim 1 wherein the radio frequency energy generator provides at least one of the group of RF energy consisting of bipolar or monopolar energy.
7. The skin treatment apparatus according to claim 1 wherein the protruding elements are located at a distance between them equal to at least twice the element diameter;
8. The skin treatment apparatus according to claim 1 wherein the radio frequency generator is operative apply to skin a pre-pulse of energy to soften the skin tissue so as to facilitate penetration of the protruding elements into the skin.
9. The skin treatment apparatus according to claim 1 wherein the needle like elements are configured to be cooled.
10. The apparatus according to claim 1, wherein the needle like elements are configured to penetrate a predetermined depth into the tissue.
11. The apparatus according to claim 1, wherein the needle like elements are configured to penetrate into dermis.
12. The apparatus according to claim 1 further comprising a controller operatively connected to the RF generator and allowing to input selected values of parameters of the RF energy.
13. A method of selectively treating discrete volumes of tissue, said method comprising:
- penetrating a plurality of electrically conductive needle like elements configured to penetrate the surface of an area of skin;
- operating a RF energy generator operably connected to the plurality of needle like elements to generate an electric current in the skin;
- operating a controller operably connected to the radio frequency energy generator; and
- treating discrete volumes of tissue such that for selected treatment parameters only the volume of tissue around the elements is treated.
14. A method of claim 13, wherein the treatment comprises creating a pattern of damaged volumes resembling the configuration of the elements.
15. A method of claim 13, wherein the treatment comprises creating a pattern of tightening in a dermal layer such that the pattern is dictated by configuration of the needles.
16. A skin treatment apparatus for selectively treating volumes of skin tissue comprising:
- a plurality of mechanically coupled needles configured to penetrate a surface of a target area of skin tissue;
- an applicator mechanically connected to the plurality of mechanically coupled needles;
- a radio frequency energy source operably connected to the plurality of needles such that the needles could be energized;
- a controller operably connected to the radio frequency energy source; and
- wherein the needles are arranged so as to treat volumes of tissue such that for selected treatment parameters tissue is spared around the treated volumes to form discrete treated volumes.
Type: Application
Filed: Feb 9, 2010
Publication Date: Jul 22, 2010
Inventor: Michael KREINDEL (Haifa)
Application Number: 12/702,723
International Classification: A61B 18/18 (20060101);