(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATIONTREATY(PCT)
`
`(19) World Intellectual Property Organization
`International Bureau
`
`(43) International Publication Date
`27 July 2006 (27.07.2006)
`
`GS)
`
`International Patent Classification:
`
`A6IB I8/T8 (2006.01)
`
`
`
`(81)
`
`(21)
`
`International Application Number:
`PCT/IL2006/000069
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`(22)
`
`International Filing Date: 18 January 2006 (18.01.2006)
`
`(10) International Publication Number
`WO 2006/077582 A2
`
`Designated States (unless otherwise indicated, for every
`kind ofnational protection available): AE, AG, AL, AM,
`AT, AU, AZ, BA, BB, BG, BR, BW,BY, BZ, CA, CH, CN,
`CO, CR, CU, CZ, DE, DK, DM, DZ, EC, EE, EG, ES, FI,
`GB, GD, GE, GH, GM, HR, HU, ID, IL,IN,IS, JP, KE,
`KG, KM, KN, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV,
`LY, MA, MD, MG, MK,MN, MW, MX, MZ, NA, NG,NI,
`NO, NZ, OM, PG, PH, PL, PT, RO, RU, SC, SD, SE, SG,
`SK, SL, SM, SY, TJ, TM, TN, TR, TT, TZ, UA, UG, US,
`UZ, VC, VN, YU, ZA, 7M, ZW.
`
`Designated States (unless otherwise indicated, for every
`kind of regional protection available): ARIPO (BW, GH,
`GM, KE, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG, ZM,
`ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM),
`European (AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI,
`FR, GB, GR, HU,IE, IS, IT, LT, LU, LV, MC, NL,PL, PT,
`RO, SE, SI, SK, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA,
`GN, GQ, GW, ML, MR, NE, SN, TD, TG).
`
`(25)
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`Filing Language:
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`(26)
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`Publication Language:
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`(39)
`
`Priority Data:
`60/644,037
`PCT/IL2005/0003 14
`
`English
`
`English
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`(84)
`
`18 January 2005 (18.01.2005)
`
`US
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`17 March 2005 (17.03.2005)
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`IL
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`(71)
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`(72)
`(75)
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`Applicant (for all designated States except US): MSq Ltd.
`LIL/LLJ; P.o.box 3021, 38900 Ceasarea (IL).
`
`Inventors; and
`Inventors/Applicants (for US only): KARNI, Ziv
`[ILAIL]; Haoranim 3, 46910 Kfar Shmaryahu (IL).
`BRITVA, Alexander
`[IL/IL]; Nitzanim 8/1,
`10500
`Migdal Haemek(IL).
`
`(74)
`
`Agent: FRIEDMAN,Mark; 7 Jabotinsky St., 52520 Ra-
`mat Gan (IL).
`
`Published:
`
`without international search report and to be republished
`upon receipt of that report
`
`For two-letter codes and other abbreviations, refer to the "Guid-
`ance Notes on Codes andAbbreviations” appearing at the begin-
`ning of each regularissue of the PCT Gazette.
`
`(54) Title: SYSTEM AND METHOD FOR TREATING BIOLOGICAL TISSUE WITH A PLASMA GAS DISCHARGE
`
`
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`(57) Abstract: Devices and methodsfortreating biological tissue using a plasma gas-discharge are disclosed herein. An electrode
`forigniting a gas flow to form a plasma gas-discharge, wherein the electrode is configured within the device such that upon encoun-
`tering a surface of the biological tissue by the electrode, a path of current from the electrode to the surface of the biological tissue
`is formed, thereby igniting the gas flow and forming the plasma gas-discharge. In some embodiments,electromagnetic interactions
`betweenthe treated biological tissue and the plasma gas discharge traversing the electromagnetic interaction gap shape the profile
`of the plasma gas discharge. According to some embodiments, the device includes an electrode for igniting gas of the gas flow, and
`electromagnetic interactions between the electrode and the skin determine, at least in part, the electromagnetic interactions that shape
`the profile of the plasma gas discharge. In some embodiments, the device further includes a housing for providing support for the
`electrode, wherein the electrode is disposed relative to the housing such that the electrode is substantially electrically unshielded by
`the housing, and the electrode is positioned to electromagnetically interact with a surface of the biological tissue to shape, at least in
`part, the plasma profile. According to some embodiments, the presently disclosed device includes a dual-purpose nozzle-electrode
`for gas delivery and for igniting the gas flow. A method of transdermal ion delivery of a plasma flux to biological tissue as a means
`of treating the biological tissue is also provided.
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`2006/077582A2|IIITIINTANNTNTININNTINAINATAAANA
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`WO 2006/077582
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`PCT/1L2006/000069
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`1
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`SYSTEM AND METHOD FOR TREATING BIOLOGICAL TISSUE
`
`WITH A PLASMA GAS DISCHARGE
`
`
`FIELD AND BACKGROUND OF THE INVENTION
`The exemplary system relates to an improved system and methodfor treating biological
`tissue, and more specifically the skin layer, via an RF plasma gas-discharge at atmospheric
`pressures where the gas nozzle-electrode which serves as an RF-energy coupling antenna that
`functions in combination with an adjacent biological tissue acting as a second virtual electrode.
`Control of the gas discharge, or plasma, is effected in multiple ways including: gas nozzle-
`electrode configuration, nature of gas(es), and gas flow parameters. This system and method
`enables a broader range of skin treatment, resurfacing, and revitalization techniques to be
`applied that can be optimized to the needs of the treatment. Specifically, conditions for low
`temperature ablation of the skin layer minimizing thermal damage, controlled and localized
`heating of the skin layer, and transdermal ion delivery are achievable.
`involves removal and/or
`Skin treatment, suchas skin resurfacing or revitalization,
`modification of the outer and near-surfaceskin layer depending on the treatment needs. Skin
`treatments can be applied to needs such as wrinkle removal, pore tightening, skin smoothing,
`muscle lifting, collagen stimulation,
`lentigo (e.g.
`tattoo, scar,
`lesion, blemish, and hyper-
`pigmentation) removal, and hair removal and growth suppression. Previously proposed
`. methods for skin treatment predominantly involve topical treatments which are either chemical
`in nature, such as creams or ointments, mechanical (i.e. abrasive), or a combination of both.
`These techniques have not demonstrated clinical efficacy in reducing skin treatment problems
`over a long-term period and preventing problem reappearance. In addition, chemical and
`mechanical “peeling” can have damaging effects on the problem skin area and/or surrounding
`tissue.
`.
`
`In addition, newer methods have been proposed for skin treatmentutilizing laser, RF
`plasma, and LED light energy to interact with the skin layer. Each of the methods poses
`advantages and disadvantagesto the application.
`Previously available alternatives are characterized by disadvantages which are obviated
`by the exemplary system. Some of the problems associated with these types of techniques
`include:
`limited operating conditions, excessive skin heating and/or burning,
`incomplete
`blemish removal, extended healing periods, rashes, and other skin irritations and/or
`complications.
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`One example of a prior art system is disclosed in US Patent No. 6,105,581 assigned to
`ArthoCare Corporation. This patent teaches using an electrically-conductive solution, such as a
`salt solution, in contact with the skin and an electrosurgical probe. The application of RF-
`energy impulses to the probe produces a plasmain the solution causing cells on the surface of
`the skin and within the spine to be ablated. The solution removes heat from the plasma
`maintaining a low temperature which mitigates the problem of excessive skin heating
`associated with laser resurfacing. This technique has been referred to in the art sometimes as
`Coblation® technology. However, teachings of this patent have, as an inherent disadvantage,
`inadequate control of skin treatment region due to plasma “hot spots” being produced in
`various areas of the applied solution, and limited application due to the need for contact of the
`probe with the skin treatment region.
`‘Another example of a prior art system is disclosed in US Patent No. 6,518,538 assigned
`to Mattioli Engineering Ltd. This patent teaches using an RF plasma gas-discharge to heat and
`selectively damage the skin layer. The skin layer to be treated is sealed to the probe and a
`vacuumis produced within the probe. An RF energy-coupled electrode and helium gas are
`introduced into the probe, whereby the plasma is produced. However, teachings of this patent
`have, as an inherent disadvantage, the limitation of operating under vacuum conditions, and the
`
`limitation of skin treatment regions suitable to probe position and obtaining suitable vacuum
`
`pressures without extraneous, adverse results.
`Another example of a prior art system is disclosed in US Patents No. 6,629,974 and
`6,723091 assigned to. Gyrus Medical Limited. This system uses an RF plasma gas-discharge of
`nitrogen to deliver its energy in a 6 mm spot to the treatment region. One of its major
`advantages over laser-based systemsis that it does not depend on an intermediate chromophore
`to convert the RF energy into heat. Thus, heat dissipation is controlled and uniform.
`
`Furthermore, multiple passes of the plasma flame over the treatment area did not result in
`additive thermal damage as in laser-based systems. However, this system has, as an inherent
`disadvantage, the limitation of operating with only a small active plasma region for skin
`treatment. Thisis due, in part, to the fact that the plasma is ignited inside the housing of the
`device. This precludes any beneficial electromagnetic interactions between the electrode and
`
`the skin surface to assist in shaping the plasmaprofile.
`
`Thus, there is a widely-recognized need for, and it would be highly advantageous to
`have, an improved system and method for heating biological tissue via an RF plasma gas-
`
`discharge devoid of the abovelimitation(s).
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`SUMMARY OF THE INVENTION
`.
`‘The aforementioned needsaresatisfied by several aspects ofthe exemplary system.
`‘It is now disclosed for the first time a device for treating biological tissue. The
`presently disclosed device includes an electrode for igniting a gas flow to form a plasma gas-
`discharge, wherein the electrode is configured within the device such that upon encountering a
`surface of the biological tissue by the electrode, a path of current from the electrode to the
`surface of the biological tissue is formed, thereby igniting the gas flow and forming the plasma
`
`. gas-discharge.
`According to some embodiments, the electrode is a nozzle-electrode including a nozzle
`portion adapted to receive the gas flow.
`a
`According to some embodiments, said nozzle-electrode is adapted to ignite the gas flow
`such that the plasma gas-discharge is formed, at least in part, outside ofthe nozzle portion.
`According to some embodiments, the device operates at or above atmospheric pressure.
`According to some embodiments, the plasma gas-discharge produced by the deviceis.
`effective to treat the biological tissue by ablating the biologicaltissue.
`According to some embodiments, the plasma gas-discharge produced by the deviceis
`effectiveto treat the biological tissue by cutting the biological tissue.
`According to some embodiments, the plasma gas-discharge produced by the device is
`effective to treat the biological tissue by transdermal ion delivery to the biological tissue.
`According to some embodiments, the plasma gas-discharge produced by the device is
`effective to treat the biological tissue by heating the biologicaltissue.
`.
`According to some embodiments, the plasma gas-discharge produced by the device is
`effective to treat the biological tissue by bio-photostimulation ofthe biologicaltissue.
`According to some embodiments, the plasma gas-discharge produced by the deviceis
`effective to treat the biological tissue by chemically reacting the plasma gas-discharge with the
`biological tissue.
`|
`According to some embodiments,the gas flow is a diffusive gas flow.
`According to some embodiments, the device further includes a gas source for producing
`the gas flow, the gas source provides at least one gas selected from the group consisting of:
`helium, argon, neon, xenon, krypton, molecular oxygen (O2), molecular nitrogen (N2), oxides
`
`of nitrogen, oxides of carbon, water vapor, a volatile organic gas, and a volatile inorganic gas.
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`According to some embodiments, the electrode is composed of at least one metal
`
`selected from the group consisting of: aluminum,silver, gold, copper, and alloys thereof.
`
`wh
`
`According to some embodiments,
`the device further includes a dielectric barrier
`associated with a surface of the electrode for reducing an electrical conductivity of the surface
`of the electrode, thereby impeding transmission of a conductive current to the surface of
`
`biological tissue.
`_ According to some embodiments, the electrode is dimensioned to form a torch-type |
`profile from the plasma gas-discharge.
`.
`|
`According to some embodiments, the electrode has a dielectric cylindrical ‘cavity
`
`attachment and is dimensioned to form the plasma gas-discharge such that the plasma gas-
`
`discharge substantially occupies the total cavity of the dielectric cylindrical cavity attachment.
`
`According to some embodiments, the electrode is dimensioned to form the plasma gas- .
`discharge with a very low current‘density and a high discharge cross-section.
`According to some embodiments, the electrodeis dimensioned to form a narrow flame-
`tongue (plasmatron) profile from the plasma gas-discharge.
`a
`According to some embodiments, the electrode is dimensioned and positioned to
`interact with the surface of the biological tissue in a way that the surface of the biological
`tissue is a non-equipotential surface, allowing for simultaneous heating of the biological tissue
`
`and maintaining the plasma gas-discharge.
`. According to some embodiments,the electrode is dimensioned with a bow]profile and
`positioned to directly contact the biological tissue in a way that the surface of the biological
`tissue is a non-equipotential surface, enabling the plasma gas-discharge to substantially fill
`interior volume ofthe electrode.
`|
`According to some embodiments,
`the electrode has a dielectric cylindrical cavity
`attachment and is dimensioned with a spherical profile for directly contacting the biological
`tissue in a way that the surface of the biologicaltissue is a non-equipotential surface, providing
`the plasma gas-discharge with a ring-typeprofile.
`
`According to some embodiments, the electrode has a dielectric cylindrical conduit
`attachment which extendsinto interior ofthe electrode directly contacting the biological tissue,
`thereby igniting the plasma gas-discharge inside the dielectric cylindrical conduit attachment,
`the plasma gas-discharge is transported to the biological tissue by the gas flow.
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`5
`According to some embodiments, the device further includes at least one additional
`component selected from the group consisting of: a laser bearn, an ultrasonic transducer, a UV
`light source, and a flash lamp, thereby additionally treating the biological tissue.
`According to some embodiments, the electrode serves as an antenna for the plasma gas-
`discharge and affects parameters ofthe gas flow for the plasma gas-discharge.
`.
`According to some embodiments, the device further includes a nozzle for gas delivery,
`the nozzle suitable for producing astrong decrease in temperature of the gas (adiabatic
`expansion).
`According to some embodiments, the device further includes a nozzle for gas delivery,
`the nozzle suitable for producing a laminar gas flow.
`According to some embodiments, the device further includes a nozzle for gas. delivery,
`the nozzle suitable for producing a turbulent gas flow.
`According to some embodiments, the device further includes a nozzle for gas delivery,
`the nozzle suitable for producing a gas flow effective for transdermal ion delivery.
`According to some embodiments, the plasma-gas discharge is produced by an RF
`power generator (amplifier) capable of producing an output RF power sufficient to ignite and
`sustain the plasma gas-discharge.
`|
`-
`According to some embodiments, the device further includes an electrode control for
`regulating a power characteristic of the electrode.
`.
`According to some embodiments,the electrode control includes an RF power sourcefor ©
`
`providing RF powerto the electrode.
`According to some embodiments, the electrode control includes a phase shifter capable
`of shifting a phase of directed traveling waves.
`. a
`According to some embodiments,
`the electrode control
`includes an impedance- |
`matching network (MN), the IMN capable of converting an aggregate impedance of the
`device including the plasma gas-discharge, the electrode, and the biological tissue (DET -
`discharge-electrode-tissue) from a nominal value to a corrected value.
`According to some embodiments, the electrode control
`includes an RF resonator
`capable of cyclically accumulating and releasing a desired amountof energy.
`According to some embodiments, the electrode control includes: (a) an RF power
`generator (amplifier) capable of producing an output RF power sufficient to ignite and sustain
`the plasma gas-discharge, (b) a pulse-width modulation (PWM) controller, the PWM controller
`capable of causing the RF power generator to deliver the output RF power in pulses of a
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`predetermined duration and amplitude with a desired frequency, (c) a phase shifter capable of
`shifting a phase of directed traveling waves, the phase shifter capable of shifting a phase of
`directed traveling waves of the output power via a phase jump in orderto facilitate both an .
`- ignition stage and an operation stage of the plasma gas-discharge, (d) an impedance-matching
`network (IMN),
`the IMN capable of converting an aggregate impedance of the device
`including the plasma gas-discharge, the electrode, and the biological tissue (DET - discharge-
`electrode-tissue) from a nominal value to a corrected value for both the ignition stage and the
`operation stage, the corrected value matching to a characteristic impedance of the RF power
`generator and the phase shifter so that the output traveling wave may sustain the plasma gas-
`discharge without being converted to a standing wave, and (e) an RF resonator connected to
`the electrode, the RF resonator capable of cyclically accumulating and releasing a desired
`‘amount of energy for the operation stage, the RF resonator further capable of concentrating the
`
`desired amount of energy for the ignition stage.
`According to some embodiments, the dielectric barrier is supplied as a dielectric
`coating on the electrode.
`.
`- According to some embodiments, the electrode is constructed primarily of aluminum
`and the dielectric barrier is supplied as an alumina coating.
`It is now disclosed for the first time a device for treating biological tissue using a
`shaped plasma profile formed from a gas flow. The presently disclosed device includes: (a) an
`electrode for igniting the gas flow to produce a plasma gas-discharge, and (b) a housing for
`providing support for said electrode, wherein said electrode is disposed relative to said housing
`such. that said electrode is substantially electrically unshielded by said housing, and said
`electrode is positioned to electromagnetically interact with a surface of the biological tissue to
`shape, at least in part, the plasmaprofile.
`According to some embodiments, the device is configured such that the plasma-gas
`discharge is substantially located outside the housing.
`According to some embodiments, the electrode is attached to the housing via an
`electrode holder, the electrode holder serves both to position the electrode relative to the
`
`~ housing and to deliver gas of the gas flow to the electrode.
`According to some embodiments, at least a portion of the electrode is exposed on the
`housing to allow direct contact with the surface of the biological tissue.
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`According to some embodiments, the disposition of the electrode is adjustable relative
`to the housing to allow movement along the surface of the biological tissue as a means of ©
`controlling a region of treatmentof the biological tissue.
`It is now disclosed for the first time a device for treating biological tissue. The
`presently disclosed device includes:
`(a) an RF power generator (amplifier) capable of
`producing an output RF power sufficient to ignite and sustain a plasma gas-discharge, (b) a
`pulse-width modulation (PWM) controller, the PWM controller capable of causing the RF
`power generator to deliver the output RF power in pulses of a predetermined duration and
`amplitude with a desired frequency, (c) a phase shifter capable of shifting a phase of directed
`traveling waves, the phase shifter capable of shifting a phase of directed traveling wavesof the
`output power via a phase jump in order to facilitate both an ignition stage and an operation
`stage of the plasma gas-discharge, (d) an impedance-matching network (IMN),
`the IMN
`capable of converting an aggregate impedance of. the device including the plasma gas-
`discharge, the electrode, and the biological tissue (DET - discharge-electrode-tissue) from a
`nominal value to a corrected value for both the ignition stage and the operation stage, the .
`_ corrected value matching to a characteristic impedance of the RF power generator and the |
`phase shifter so that the output traveling wave may sustain the plasma gas-discharge without
`being converted to a standing wave, and (e) an RF resonator connected to the electrode, the RF
`resonator capable of cyclically accumulating and releasing a desired amount of energy for the
`operation stage, the RF resonator further capable of concentrating the desired amount of energy
`for the ignition stage.
`|
`.
`According to some embodiments, coupled power is delivered from the RF power
`generator.
`According to some embodiments, the output RF power delivered to the plasma gas-
`discharge is coupled in continuous or pulsing mode.
`According to some embodiments, the phase shifter includes a trombonetype.
`According to some embodiments, the phase shifter is at least partially constructed of
`coaxial cable.
`oe
`According to some embodiments, a phase shift provided by the phaseshifter is variable.
`According to some embodiments, the IMN includesa fixed structure characterized by a
`shape selected from the group consisting of: L-shaped, T-shaped, and 2-shapedstructure.
`According to some embodiments,
`the IMN includes a broadband impedance
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`tissue is treated by cutting the
`
`the biological
`
`.
`According to some embodiments, the IMN is variable.
`According to some embodiments, the device further includes: (f) a feeding cable, the
`feeding cable connecting the electrode and the RF resonator with the IMN.
`According to some embodiments, the feeding cable has a resonance length defined by
`n*4/2 length, where 4 is a wavelength of the output RF power in material of the feeding cable
`and n is a whole number.
`.
`|
`It is now disclosed for the first time a device for treating biological tissue using a
`shaped plasmaprofile formed from a gas flow. The presently disclosed. device includes: (a) a
`nozzle-electrode for gas delivery and for igniting the gas flow to produce a plasma gas-
`discharge, and (b) a housing providing support for said nozzle-electrode, wherein said nozzle-
`electrode is disposed relative to said housing such that said nozzle-electrode is substantially
`electrically unshielded by said housing,
`and said nozzle-electrode is positioned to
`electromagnetically interact with a surface of the biological tissue to shape,at least in part, the
`plasmaprofile.
`It is now disclosed for the first time a method for treating biological tissue. The
`presently disclosed method includes: (a) supplying agas flow. to an electrode, (b) upon
`bringing a surface of the biological tissue and an electrode into proximity with each other such
`that the electrode and the biological tissue are substantially electrically unshielded from each.
`other, igniting the gas flow to form a plasma gas-discharge, and (c) subjecting the surface of
`the biological tissue to the plasma-gas discharge, thereby treating the biological tissue.
`According to some embodiments, the biological
`tissue is treated by ablating the
`biological tissue.
`According to some embodiments, the biological
`biological tissue.
`According to some embodiments, the biological tissue is treated by transdermally
`delivering ions to the biological tissue.
`According to some embodiments,
`biological tissue.
`embodiments,
`some
`According to
`photostimulating the biological tissue.
`| According to some embodiments, the biological tissue is treated by chemically reacting
`the plasma gas-discharge with the biological tissue.
`
`tissue is treated by heating the
`—
`treated by bio-
`
`the biological
`
`tissue
`
`is
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`According to some embodiments, the biological tissue is electrically grounded in order
`to interact with the plasma gas-discharge.
`According to some embodiments, the biological tissue is electrically floating in orderto
`interact with the plasma gas-discharge.
`According to some embodiments,
`atmospheric pressure.
`
`the plasma gas-discharge operates at or above
`
`According to some embodiments, the method further includes: (d) producing an output
`RF powersufficient to ignite and sustain the plasma gas-discharge by means of an RF power
`generator (amplifier), (e) causing the RF power generator to deliver the output RF power in
`pulses of a predetermined duration and amplitude with a desired frequency by means of by
`means of a pulse-width modulation (PWM)controller, (f) shifting a phase of directed traveling
`wavesof the output powervia a phase jump in order to facilitate both an ignition stage and an
`operation stage of the plasma gas-discharge by means of a phase shifter, (g) converting an
`aggregate impedance including the plasma gas-discharge, the electrode, and the biological
`tissue (DET - discharge-electrode-tissue) from a nominal value to a corrected value for both
`the ignition stage and the operation stage, the corrected value matching to a characteristic.
`impedance of the RF power generator and the phase shifter so that the output traveling wave
`may sustain the plasma gas-discharge without being converted to a standing wave by means of
`an impedance-matching network (IMN), and (h) cyclically accumulating and releasing a
`desired amount of energy for the operation stage,
`the RF resonator further capable of
`concentrating the desired amount of energy for the ignition stage by means of an RF resonator
`connected to the electrode.
`
`According to some embodiments, the step of igniting the gas flow from the electrode
`includes igniting the gas flow from an electrode attached to the device via an electrode holder,
`the electrode holder also serves to deliver a gas to the electrode.
`According to some embodiments, the step of igniting the gas flow from the electrode
`includes igniting the gas flow from an electrode located in direct contact with the surface of the
`biologicaltissue.
`According to some embodiments, the step of igniting the gas flow from the electrode .
`includes igniting the gas flow from an electrode movable on the surface of the biological tissue
`aS a meansofaltering a location oftreating the biological tissue.
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`(d) “positioning a
`the method further includes:
`According to some embodiments,
`dielectric barrier between the electrode and the surface of the biological tissue, the dielectric
`barrier impeding transmission of a conductive current.
`.
`.
`According to some embodiments, the step of igniting the gas flowfrom the electrode
`includes igniting the gas flow from an electrode exposed to atmosphere and having a
`dimension and a profile for producing the plasma gas-discharge that has a torch-typeprofile.
`According to some embodiments, the step of igniting the gas flow from the electrode
`includes igniting the gas flow from an electrode having a dielectric cylindrical cavity
`attachment and having a dimension and a profile for producing the plasma gas-discharge that
`occupiesthe total cavity of the dielectric cylindrical cavity attachment.
`According to some embodiments, the step of igniting the gas flow from the electrode
`includes igniting the gas flow from an electrode having a dimension and a profile for producing
`the plasma gas-discharge with a very low current density and a high discharge cross-section.
`According to some embodiments, the step of igniting the gas flow from the electrode
`15
`includes igniting the gas flow from an electrode having a dimension andaprofile for producing
`the plasma gas-discharge with a narrow flame-tongue (plasmatron)profile.
`_ According to some embodiments, the step of igniting the gas flow from the electrode
`includes igniting the gas flow from an electrode having a dimension andaprofile for
`interacting with the surface of the biological tissue, in a way that the surface of the biological
`tissue is a non-equipotential surface, allowing for simultaneousheating of the biological tissue
`and maintaining ofthe plasma gas-discharge.
`According to some embodiments, the step of igniting the gas flow from the electrode
`includes igniting the gas flow from an electrode having a bowl profile for directly contacting
`the biological tissue in a way that the surface of the biological tissue is a non-equipotential
`surface, enabling the plasma gas-dischargeto fill interior volumeofthe nozzle electrode.
`According to some embodiments, the step of igniting the gas flow from the electrode
`includes igniting the gas flow: from an electrode having a dielectric cylindrical cavity
`attachment and having a spherical profile for partially directly contacting the biological tissue
`ina way that the surface of the biological tissue is a non-equipotential surface, providing the
`plasma gas-discharge with a ring-type profile.
`|
`.
`According to some embodiments, the step of igniting the gas flow from the electrode
`includes igniting the gas flow from an electrode having a dielectric cylindrical conduit
`attachment which extends into interior of the electrode directly contacting the biological tissue
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`25
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`WO 2006/077582
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`PCT/1IL2006/000069
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`11
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`listed.
`
`which yields a plasma gas-discharge ignited inside the dielectric cylindrical conduit
`attachment, the plasma gas-dischargeis transported to the biological tissue by the gas flow.
`According to some embodiments, the method further includes: (d) employing at least
`“one additional component selected from the group consisting of: a laser beam, an ultrasonic
`transducer, a UV light source, and a flash lamp to additionallytreat the biological tissue.
`' According to some embodiments, the step of providing a gas flow includes providing a
`gas flow having flow characteristics suitable to produce a strong decrease in temperature of the
`gas (adiabatic expansion).
`According to some embodiments, the step of providing a gas flow includes providing a
`gas flow having flow characteristics suitable to produce a laminar gas flow characteristic.
`According to some embodiments, the step of providing a gas flow includes providing a
`gas flow having flow characteristics suitable to produce a turbulent gas flow characteristic.
`|
`According to some embodiments, the step ofproviding a gas flow includes providing a-
`gas flow having flow characteristics suitable to facilitate transdermal ion delivery.
`According to some embodiments,the steps of (a) through (c) are performed in the order
`,
`.
`It is now disclosed for the first time a method for treating biological tissue. The
`presently disclosed method includes: (a) supplying a gas flow to an electrode, (b) allowing a
`path of current to form from the electrode to a surface of the biological tissue to concomitantly
`ignite the gas flow to form a plasma gas discharge, and (c) subjecting the surface of the
`biological tissue to the plasma-gas discharge, thereby treating the biological tissue
`It is now disclosed for the first time a method for treating biological tissue using a
`plasma gas-discharge. The presently disclosed method includes: (a) producing an output RF
`power sufficient to ignite and sustain the plasma gas-discharge by means of an RF power
`generator (amplifier), (b) causing the RF power generator to deliver the output RF powerin
`pulses of a predetermined duration and amplitude with a desired frequency by means of by
`means ofa pulse-width modulation (PWM) controller, (c) shifting a phase ofdirected traveling -
`wavesof the output power via a phase jumpin orderto facilitate both an ignition stage and an
`operation stage of the plasma gas-discharge by means of a phase shifter, (d) converting an
`aggregate impedance including the plasma gas-discharge, the electrode, and the biological
`tissue (DET - discharge-electrode-tissue) from a nominal value t