TECHNOLOGICAL FIELD

[001 ] The apparatus and method relate to cosmetic devices and more specifically to such devices and methods for non-invasive treatment of soft tissues such as adipose tissue.

BACKGROUND OF THE INVENTION

[002] Adipose tissue is located under the skin layer. Thus, energy applied to the skin surface to degrade adipose tissue must pass through the skin layer to reach the adipose tissue without damaging the skin.

[003] Various devices have been used for the treatment of adipose tissue, partial removal of which leads to what is known as "circumference reduction." One popular method of fat or adipose tissue treatment is liposuction. This is an invasive technique involving mechanical disruption of the fat with subsequent suction of the resulting debris out of the body. The main disadvantage of this method is its invasive character.

[004] Methods for treating adipose tissue based on thermal destruction of fat by exposing adipose tissue to focused microwave or ultrasound waves exist. The intensity and the focusing of the energy are determined so as to selectively destroy fat cells without damaging the skin or deep tissues. In some instances high intensity focused ultrasound (HIFU) is used for destruction of adipose tissue. HIFU is applied in pulses so as to produce cavitation, which destroys fat cells.

[005] The use of applicators having vacuum chambers to pull a segment of skin into a chamber and apply thereto various energy treatments is known. Such applicators commonly contain a rigid plate or a flexible membrane, or a combination of a rigid plate and a flexible membrane located in the interior of the chamber. The plate or membrane is forced to rapidly move in the chamber away from the surface of the skin, in order to generate a negative pressure in the portion of the chamber interior between the surface of plate and the skin.

[006] The movement of the plate or membrane sucks the skin outwardly from a subject's body into the chamber, where commonly, for example, RF voltage is applied to the skin. The outwardly skin movement from the subject's body into the chamber stretches the skin and increases the pressure on the skin at the edges or corners of the chamber rim. This stretching pressure brings about unpleasant and frequently painful sensations of the treated person.

[007] Plate or membrane excursion and skin into the chamber movement are limited since pockets of trapped air remain in the chamber and air pressure in the pockets grows as the plate or membrane being actually a piston moves upwardly.

BRIEF SUMMARY

[008] Described are a method and apparatus for the treatment of soft tissue, such as adipose tissue, muscle tissue or connective tissue. In accordance with the method and apparatus, a pressure pulse is applied to a region of skin overlying a volume of soft tissue. The pressure pulse has at least one positive pressure phase and at least one negative pressure phase with respect to ambient pressure. The positive pressure phase duration is substantially longer than the negative pressure phase duration. The positive pressure phase duration is sufficient to ensure synchronous movement between the skin surface overlying the soft or adipose tissue volume and the soft tissue itself. The pressure change in course of the positive pressure phase is substantially slower than the pressure change during the negative pressure phase. The positive pressure phase slowly displaces or pushes all of the skin layers, including the adipose tissue into the treated body. The negative pressure phase is fast and pulls or bends the tissue to be treated outwards from the body.

[009] In the case of adipose tissue, the action of the negative phases causes

destruction of fat cells, with little or no damage to other tissues, since adipose tissue or fat cells are larger and weaker than most other cells. The intensity and time profiles of the pressure pulse are selected to cause maximal destruction of the adipocytes, with minimal damage to other tissues. In the case of other types of soft tissues, such as muscle tissue or connective tissue, the pulses create a massaging effect of the tissue.

[0010] In one embodiment of the apparatus, the positive pressure phase is

generated by a mechanical gear that slowly pushes a rod with a piston or plate into the treated body. Upon reaching a desired skin and tissue strain, the gear disengages the rod and a spring rapidly releases the rod generating the negative pressure phase with respect to the ambient pressure.

[001 1 ] During such applicator operation the skin in course of slow positive pressure application exhibits maximal movement and minimal skin stretching. The adipose tissue layer follows the deflection or bending of the outer skin layers and practically moves in a joint movement with the outer skin layers movement. Since no skin stretching takes place when the skin bends or is displaced outward of the subject body, the treated subject is not sensing pain or other unpleasant sensations. Another embodiment of the apparatus is based on actuators that generate a push-pull (positive-negative) action by controlled application and removal of pressure pulses of a gas such as air into an actuator.

[0012] In the case of the treatment of adipose tissue, the temperature of the adipose tissue may be raised during the treatment in order to enhance the effect of the cell disruption by the pressure pulse. The adipose tissue is typically heated to a temperature equal or higher than normal body tissue temperature (37 degree C), but not high enough to damage the skin surface, prior to and/or simultaneously with the application of the pressure pulse. Any known method for heating adipose tissue may be used, such as an RF current through the tissue via conducting electrodes applied to the surface of the skin, radiation of the skin surface with light from a flash lamp or laser, microwave power radiated into the tissue, and high intensity ultrasound. The applicator may be configured to apply heat to the tissue volume to be treated, and the heat is typically applied at a depth below the skin surface. [0013] In yet another embodiment, an applicator is disclosed having valves that open in course of the push phase to let the air that may be trapped between skin and piston to get out so that the piston can touch the skin tightly.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to understand the invention and to see how it may be carried out in practice, a number of exemplary embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0015] FIG. 1 illustrates an exemplary system for applying a positive and negative pressure phase to a skin surface in accordance with one embodiment of the method and apparatus;

[0016] F GS. 2A - 2C show principles of operation of an exemplary embodiment of an applicator suitable for generating positive and negative pressure phases with reduced pain to the treated subject;

[0017] FIG. 3 is a schematic illustration of an exemplary positive and negative pressure phases generated according to the present method;

[0018] FIGS. 4A - 4D are schematic illustrations of principles of operation of

another exemplary embodiment of an applicator suitable for generating positive and negative pressure phases according to the present method;

[0019] FIG. 5 is a schematic illustration of still another exemplary applicator

suitable for generating positive and negative pressure phases according to the present method.

[0020] FIG. 6 is a schematic illustration of an additional exemplary embodiment of RF electrodes configuration.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0021] FIG. 1 shows an exemplary apparatus for treating soft body tissues, such as adipose tissue, in accordance with one embodiment of the apparatus. An applicator 100, to be described in detail below, is adapted in operation to be applied to the skin of a subject 104. The applicator 100 is connected to a control unit 106 via electrical wires in a cable 102. The control unit 106 includes a power source 108. The control unit 106 also contains a temperature affecting unit 1 12 that cools a fluid such as ethanol or water for maintaining the applicator 100 at a predetermined temperature as explained below. The control unit 106 has an input device such as a keypad 1 10 that allows an operator to input selected values of parameters of the treatment, such as the intensity and duration of the positive and negative phases and a pulse or phase repetition rate.

[0022] FIGS. 2A - 2C show principles of operation of an exemplary embodiment of an applicator suitable for generating positive and negative pressure phases with reduced or even free of pain to the treated subject. FIG. 2A illustrates an initial state where applicator 200 including at least a chamber 228 having a rim 250 being applied to skin surface 204 such that rim 250 is in contact with the skin surface overlaying the adipose tissue. A piston 208 is a rigid body excursing in chamber 228. Piston 08 has a curved convex surface contacting the skin surface 204 when applicator 200 is being applied to skin surface 204. When a positive pressure phase (FIG. 2B), relative to ambient, is applied to the applicator, piston or actuator plate 208, pushes the skin layer 212 inward into the subject body, so as to create a positive pressure on the skin layer 212 and underlying adipose layer 216. The skin 212 and adipose tissue 216 follow the convex contour of the piston. During the slow push action, the skin will follow the piston contour without strain and pain while the adipose tissue may flow out of the operational zone under the pressure as shown by arrows 220, leaving a thinner adipose tissue convex layer under the actuator plate 208. Valves 244 will open in course of the push phase to let the air that may be trapped between skin 204 and piston to get out so that the piston can touch the skin tightly.

[0023] When the actuator plate 208 is displaced outward of the subject body (FIG.

2C) as it is schematically shown by arrow 224, so as to create a negative pressure in chamber 228, the skin layer 212 is pulled inside applicator 200 chamber 228 forming a protrusion 232. The action of pulling the skin into chamber 228 does not stretch the skin segment located at the rim 250 of chamber 228 and alleviates or even precludes the pain to the treated subject, even if the pulling action is very fast, since the skin being bended into the chamber, experiences only bending and not stretching action. One or more than one one-way valves 244 may be used to prevent occasional pressure build up in air pockets 240. During the pull phase, these valves are closed, so vacuum can be formed to pull the skin. The intensity and time profiles of the pressure pulse may be selected to cause maximal destruction of the adipose tissue, with minimal damage to other tissues. The push phase may be 0. 1 - 10 seconds long, the pull phase may be 0.1 -100 milliseconds long or 0.1 - l Omilliseconds long. Applicator 200 could have an opening 254 communicating with surrounding atmosphere and preventing build-up of pressure in chamber 228 in course of protrusion 232 formation. Control unit 106 (FIG. 1 ) is operative to control and activate the applicator 200.

[0024] The author of the present method and apparatus has experimentally proved that when the force applied to the skin in course of positive pressure phase slowly changes its magnitude, the adipose tissue, which behaves more like a fluid, follows the skin easily or moves almost simultaneously with the skin.

[0025] The force required for slowly pushing the skin and adipose tissue is very small, therefore the pressure gradients formed are small. When the transition to negative pressure phase is fast, the pulling forces on the adipose tissue are substantially larger. Basically, this may be explained by second Newton law, faster mass movement means greater acceleration, which may be developed by application of a larger force. These pulling forces generate negative pressure in the deeper fat layer. Actually, this pulling forces and negative pressure persists as long as the skin and the adipose tissue are accelerated outwardly. It was found experimentally, that a negative pressure of up to minus one Bar may be developed inside the adipose tissue that behaves like a fluid at a depth of 5mm, about minus 0.7 Bar to 10mm below and about minus 0.4 Bar 15mm below a flexible, but not stretched upper skin-like layer. The negative and positive pressure phases have a period and amplitude selected to effect maximum destruction of fat cells and minimal damage to other tissues.

[0026] Persons skilled in the art will appreciate that other applicators may be

suitable for generating positive and negative pressure phases with reduced or even free of pain to the treated subject. Such applicators may include an applicator that creates a positive and negative pressure pulse by generating a spark in a liquid or an applicator having a magnetic solenoid actuator, both applicators described in assignee's US Patent 7,857,775 herein incorporated by reference in its entirety. Other actuators may also include positive and negative pressure actuators such as compressed gas actuators, motor actuators and spring actuators.

[0027] According to the present method, and as shown in FIG. 3, which is a

schematic illustration of an exemplary positive and negative pressure phases generated according to the present method, the "push" phase or positive pressure phase has duration substantially longer than the negative pressure phase duration. The positive pressure phase duration is sufficient to ensure joint skin-adipose tissue movement of the outer skin layers 212 and the soft or adipose tissue layer 216. For example, the positive pressure phase 304 may be between 0.1 sec to 10 sec or. Such slow motion or displacement of the skin and adipose tissue layers ensures a joint movement between the outer skin layers 212 overlying the adipose tissue volume and the adipose tissue 216. The pressure applied to the skin layers 212 during the positive pressure phase, also changes substantially slower than the pressure changes during negative pressure phase. The negative pressure phase 308 follows immediately the positive pressure phase 304. The duration of negative phase 308 is extremely short and may be between 0.1 msec and 10 msec. During this fast negative pressure phase skin and adipose tissue layers are both accelerated in their joint movement outwardly; high level of acceleration is generated by the fast action, according to Newton's second law this acceleration produces forces on the tissue layers which generate the large peak of negative pressure in the subcutaneous tissue. [0028] RF electrodes or ultrasound transducers, or illumination sources that may be incorporated in the applicator could be used to apply the treatment energy to a significant portion of adipose tissue 216 and cause the desired heating which enhances the effect of the negative pressure on the tissue. In order to enhance the effect of the negative pressure on the adipose tissue the tissue is heated above its normal temperature. It is known that the external skin layers normally have a temperature of about 30-33 degree Celsius. The temperature usually increases from the outside skin layers to the inner skin layers and in particular to the adipose tissue or fat layer located between the skin and muscle. Because of this temperature gradient a substantial volume of the fat is below 36.6C. The authors of this method have found experimentally that heating the fat above 37 degree C enhances fat cell breaking by negative pressure pulse.

[0029] FIG. 4 is a schematic illustration of an exemplary applicator suitable for generating positive and negative pressure phases according to the present method. Applicator 400 (FIG. 4A) includes an actuator 404 and a rod 408 to which a flexible plate or membrane 412 is attached. An electrode 416 may also be attached to rod 408 or joint to the membrane. Actuator 404 may be a rack and pinion mechanism or a worm gear driven by a Direct Current (DC) motor. Alternatively, actuator 404 may be driven by a stepper motor with a suitable gear.

[0030] Actuator 404 is configured to apply to the skin a positive pressure and in operation it slowly pushes the skin into the treated subject body at a speed that ensures joint movement between the outer skin layers 212 (FIG. 4B) and the soft or adipose tissue layer 216. For example, the deflection or sag of the skin 212, depending on the treated skin segment and the size of the applicator, may be 5 mm to 20 mm and the positive pressure phase duration may be between 0. 1 sec to 10 sec. In course of skin deflection process, rod 408 tensions spring 420 (FIG. 4A) and when the desired deflection magnitude is reached a ratchet-and-pawl type mechanism 424 or simply a pin may move into a position shown by arrow 428 and lock rod 408 in a position where maximal pressure is applied to the skin. Applicator 400 could have an opening 444 communicating with surrounding atmosphere and preventing build-up of pressure in chamber 428 in course of protrusion 432 (FIG. 4C) formation.

[0031 ] The advantage of such applicator operation is that the skin in course of slow positive pressure application exhibits maximal movement and minimal skin stretching. The adipose tissue layer 216 has enough time to follow the deflection or bending of the outer skin layers 212 and practically moves in a joint movement with the outer skin layers movement.

[0032] Upon reaching this condition ratchet mechanism 424 could be released and spring 420 releases rod 408, membrane 412 (FIG. 4A) and skin that move upward with high acceleration generating the negative pressure phase. The duration of the negative pressure phase may be between 0.1 msec and 10 msec. Soft tissues and in particular adipose tissue is under high acceleration during this fast movement, so negative pressure is generated deep inside the tissue and it develops pulling forces destructing adipose tissue cells; and since the skin was already deflected or bended in course of the positive pressure phase into the subject body without being stretched; in course of the negative pressure phase the bended skin segment simply bends in opposite direction outward of the subject body becoming a protrusion 432. Since no skin stretching takes place when the skin bends or is displaced outward of the subject body, the treated subject is not sensing pain or other unpleasant sensations.

[0033] RF voltage source 108 (FIG. 1 ) becomes operative to apply through

electrode 416 and circular electrode 440 (FIG. 4D) RF voltage to the skin 212 and adipose tissue 216 in the protrusion. Current induced by the applied RF voltage, schematically shown by broken lines 450 (FIG. 4D) affects almost all of the adipose tissue 216 located in the protrusion 432. Control unit 106 (FIG. 1 ) is operative to control and activate the applicator 400.

[0034] The upstream excursion of the membrane 412 and rod 408 may be limited by including in the applicator a simple photoelectric protrusion sensor 460 or a mechanical stop, further minimizing the risk of skin stretching. The positive and negative pressure phases may be repeated until a desired treatment effect is reached. [0035] FIG. 5 is a schematic illustration of another exemplary applicator suitable for generating positive and negative pressure phases according to the present method. Applicator 500 includes an actuator 404 and a rod 408 to which a flexible plate or membrane 512 is attached. An electrode 516 may also be attached to rod 408 or joint to the membrane 512. Membrane 512 may be inserted into a flexible hinge type circular channel 544 easy flexed as shown by arrows 548. The stiffness of channel 544 may be lower than the stiffness of membrane 512. This allows greater flexibility and larger or higher protrusion formation. Otherwise, operation of applicator actuator 404 is similar to the operation of applicator 400 as disclosed in relation to FIG. 4.

[0036] FIG. 6 is a schematic illustration of an additional exemplary embodiment of RF electrodes configuration. RF voltage source 436 is operative to apply between at least one pair of diametrically opposed electrodes 540 being a segment of a circle RF voltage. The RF voltage is applied to the skin and adipose tissue being sucked into the protrusion. Current induced by the applied RF voltage affects almost all of the adipose tissue located in the protrusion. In an additional embodiment the RF may be applied alternatively between the pair of diametrically opposed electrodes 540 or between at least one of 540 electrodes and central electrode 516.

[0037] According to another example, the rack and pinion mechanism or a worm gear driven by a Direct Current (DC) motor or driven by a stepper motor with a suitable gear could be configured to operate as an actuator and slowly move piston 208 (FIG. 2) into the treated subject body at a speed that ensures joint movement between the outer skin layers 212 (FIG. 4B) and the soft or adipose tissue layer 216. Upon reaching suitable depth of piston 208 excursion into the treated subject body (and suitable positive pressure) ratchet mechanism 424 (FIG. 4) could be released and spring 420 could facilitate piston 208 upward movement with high acceleration generating the negative pressure phase.

[0038] Optionally, applicators 400 and 500 may include one or more illumination sources operative to radiate the protrusion by one or more wavelengths heating the adipose tissue in protrusion 432. In further embodiment applicators 400 and 500 may include more than one source of tissue temperature affecting energy. For example, a source of ultrasound energy may be included in any one of the applicators.

[0039] The negative and positive pressure phases repetition rate may be slow, typically between 10 to 0.1 cycles per second. It has been found that slow movement of the skin into the body caused by positive pressure phase and abrupt application of negative pressure phase i mmediately following the positive pressure phase is more useful in destruction of fat cells, with little or no damage to other tissues, than application of fast positive and negative phases.

[0040] The present method and apparatus enable a better adipose tissue destruction and circumferences reduction. No skin pre-treatment or skin post-treatment is required increasing treated subject comfort. Absence of stretch of a skin segment located at the rim of the chamber of the applicator alleviates and even precludes pain to the treated subject.

[0041 ] While the exemplary embodiments of the method and apparatus for adipose tissue destruction have been illustrated and described, it will be appreciated that various changes can be made therein without affecting the spirit and scope of the method and apparatus. The scope of the method and apparatus, therefore, is defined by reference to the following claims: