WO2015083155A1

WO2015083155A1 - Apparatus for generation of non-thermal plasma for oral treatment, plasma applicator and related method

Info

Publication number: WO2015083155A1
Application number: PCT/IL2014/051041
Authority: WO
Inventors: Amnon Lam; Eliezer FUCHS; Aviad HARHOL
Original assignee: Nova Plasma Ltd
Priority date: 2013-12-02
Filing date: 2014-12-01
Publication date: 2015-06-11
Also published as: IL245782A0

Abstract

An apparatus is provided for generation and application of non-thermal plasma, the apparatus being configured to the use thereof for oral treatment. In some embodiments the apparatus comprises a plasma applicator, configured to generate plasma in a region adjoining a surface portion of a living body. The plasma applicator comprises one or more electrically conducting RF electrodes. The RF electrodes are electrically inter-connected and configured to apply an RF EM field suitable for ionizing gas at atmospheric pressure for generation of plasma in at least one region adjoining the RF electrodes and adjoining the surface portion of the living body. An RF power source configured to supply a plasma-generating electromagnetic RF power to the plasma applicator is also provided. A related method for oral treatment is further provided. In some embodiments thereof the method may be employed for teeth bleaching.

Description

APPARATUS FOR GENERATION OF NON-THERMAL PLASMA FOR ORAL TREATMENT, PLASMA APPLICATOR AND RELATED METHOD

TECHNICAL FIELD

The invention, in some embodiments, relates to the field of generation and application of non-thermal plasma, and more particularly, but not exclusively, to the use thereof for oral treatment.

BACKGROUND

Non-thermal plasma has gained recognition during recent years as a suitable technique for assisting and expediting various treatments of living tissues. Generally, plasma refers herein to ionized gas, including positively charged ions and negatively charged electrons, wherein the whole volume of the ionized gas is roughly neutral. Positively charged ions are generally referred to herein simply as "ions" whereas negatively charged electrons are referred to herein as "electrons". Neutral atoms and molecules are referred to as "neutrals".

Non-thermal plasma refers to plasma wherein the neutrals' temperature, dictated by the neutrals' average random velocity, is low enough so as not to thermally damage biological matter (e.g. living tissue) with which the plasma interacts. In some applications ions temperature in a non-thermal plasma may be below about 55 degrees C or even below about 40 degrees C. Some embodiments of non-thermal plasma may involve ions at yet higher temperatures, particularly if employed to interact with biological matter for short periods of time.

Non-thermal plasma may be generated, according to some techniques, by selectively exciting electrons in the gas, so that neutrals gain only a minute increase or even a negligible increase to their average kinetic energy. Plasma in which electrons' temperature is substantially different from the neutrals' temperature is referred to as a non-equilibrium plasma. An exemplary technique for generating non-equilibrium plasma may employ a radio-frequency (RF) electromagnetic (EM) field applied to a region in space where plasma is to be generated, the region containing a volume of fluid, typically gas. Characteristics of the applied field, such as frequency and field strength, are selected so that electrons are strongly accelerated by the field, whereas ions and molecules, having a much higher mass than the electrons', are much less accelerated. In a non-equilibrium plasma, neutrals and ions may retain relatively low temperatures, e.g. close to room temperature, whereas electrons may have average kinetic energies that are higher by two or even three orders of magnitude. The use of non-thermal plasma for treatment of living tissues often involves the generation of non-equilibrium plasma at atmospheric pressure by electromagnetic excitation within a region of space situated distantly from the treated zone, so that the EM field does not substantially affect the tissue. Gas or gases, e.g. air, are made to flow through the region of plasma generation, thereby generating chemically active species such as free radicals and oxidizers, that are then guided, e.g. using a tube, towards the zone to be treated. US patent 8,294,369 discloses a plasma generator for delivering a generated plasma to an area that is at a distance from the area where the plasma is initially generated. The plasma generator includes a dielectric tube portion extending from a gas inlet to a discharge aperture. The plasma generator further includes an anode formed at least substantially around a portion of the discharge tube, wherein the anode is electrically coupled, via an electrical connection, to a power supply. The plasma generator further includes a cathode formed at least substantially around a portion of the discharge tube, wherein the cathode is electrically coupled, via an electrical connection, to the power supply. The plasma generator further includes an elongate discharge tube attached or coupled to the discharge aperture such that when a generated plasma is produced, the generated plasma flows through the discharge tube.

US patent application 2012/0276499 discloses an interdental treatment device comprising a generator for generating a non-thermal gaseous plasma at a temperature suitable for use in oral treatment and an applicator of the non-thermal plasma. The applicator may comprise a hollow needle member for directing a jet of the non-thermal plasma interdentally. Alternatively the applicator may comprise an interdental brush having a hollow head for receiving a non-thermal gaseous plasma, the head having at least one lateral opening for the discharge of the plasma. SUMMARY

Aspects of invention, in some embodiments thereof, relate to an apparatus for generation and application of non-thermal plasma, and more particularly, but not exclusively, to the use thereof for oral treatment. Oral treatment may include medical treatment, therapeutic treatment such as wound healing, sterilization of tissue surfaces such as wounds and teeth cavities, surface treatment of teeth, e.g. prior to crown bonding, and cosmetic treatment such as teeth whitening.

Plasma generation involves various types of excitations, these excitations having various time constants for decay. For example, positively charged ions and negatively charge electrons, generated by the excitation and ionization of initially neutral atoms and molecules, may recombine over a time scale shorter than a millisecond, e.g. on the order of magnitude of microseconds. Recombination of electrons and ions typically involves emission of light, such light is therefore emitted only over time scales equivalent to that of the recombination process.

Plasma may generally include also excited species which decay over times longer than recombination decay time, e.g. on the order of magnitude of 1 second, such as some types of free radicals. Thus, when plasma is generated at a distance from a zone to be treated and then guided towards that zone, only excited species that decay over relatively long times may survive the travel and affect the treated zone. Species with decay times shorter than the travel time from the plasma generation region to the treatment zone may decay during the travel, and consequently may not contribute to treatment.

Teeth whitening is a particular example of use of the devices, apparatuses and methods described herein. According to some embodiments oxidizers that are generated in the plasma may be chemically active in decomposing stains on teeth enamel and in teeth dentin. According to some embodiments a bleaching gel may be employed, e.g. by applying a layer of gel, foam, or any emulsion suitable for assisting bleaching, on the surface of a tooth desired to be bleached. A bleaching emulsion such as a bleaching gel may comprise oxidizers such as hydrogen peroxide and carbamide peroxide. In some embodiments, applying plasma in a region adjoining a tooth may considerably enhance and expedite the bleaching process. Particularly, applying plasma in a region adjoining a tooth covered with a bleaching emulsion may further yet enhance and expedite the bleaching. For example, applying the plasma-generating EM field in a region adjoining the tooth may be beneficial as the EM field excite water molecules in the emulsion and around the tooth, thereby elevating the emulsion temperature and enhance emulsion activation.

Species having a short decay time may be particularly important and effective in enhancing and expediting teeth whitening and/or gel-assisted teeth whitening. For example high energy electrons, accelerated by the plasma generating EM field may break chemical bonds of tooth pigments and stains, thereby assisting in cleaning and discoloring the tooth. Free radicals generated in the plasma generation region, such as · OH, are more abundant within that region rather than in neighboring regions, resulting in an increased efficiency of the plasma- enhanced processes (such as bleaching). High energy photons, substantially emitted during plasma generation within the plasma-generation region, may be particularly effective compared to massive particles in the plasma. Such photons may penetrate through gel layer or an emulsion layer disposed on a tooth much more effectively than a massive particle such as an excited molecule, an ion and even a high-energy electron. Consequently, such photons may interact with chemical bonds of pigments and stains on the tooth, may excite molecules to higher energy states and induce or accelerate or facilitate chemical reactions of such pigments and staining materials with reagents of the bleaching emulsion.

It is therefore highly advantageous to generate plasma in close proximity to the treatment zone, such that excited species with relatively short decay times may also contribute to treatment. For example, light that is emitted intensely in the plasma generation region (relative to emission intensity in surrounding regions) may be exploited to enhance photochemical and photocatalytic reactions useful for treatment. It may also be advantageous to generate plasma in a region adjoining the treatment zone, so that plasma and related excited species may affect a treatment substantially immediately after the generation thereof and substantially in close proximity to the region of generation.

There is thus provided according to an aspect of some embodiments an apparatus for generation and application of non-thermal plasma, the apparatus being configured to the use thereof for oral treatment. In some embodiments the apparatus comprises a plasma applicator, configured to generate plasma in a region adjoining a surface portion of a living body. The plasma applicator comprises one or more electrically conducting RF electrodes. The RF electrodes are electrically inter-connected and configured to apply an RF EM field suitable for ionizing gas at atmospheric pressure for generation of plasma in at least one region adjoining the RF electrodes. The plasma applicator further comprises a gas supply conduit having at least one discharge aperture configured to discharge gas from the conduit to at least one region of plasma generation. The plasma applicator further comprises a suction conduit having at least one suction opening and configured to covey gaseous and liquid fluids from the region of plasma generation and adjoining regions through the suction opening, by suction.

In some embodiments the RF electrodes are electrically associated with an RF power source. In use, the RF power source may supply electric power to the RF electrodes for applying the RF EM field for the generation of plasma.

In some embodiments the gas supply conduit may be associated with a gas source (e.g. a gas reservoir) for providing fluid communication between the gas source and the discharge aperture. In some embodiments the gas reservoir may be pressurized, storing gas at a pressure substantially higher than one atmosphere. In some embodiments gas may be supplied from the reservoir to the discharge aperture through a control valve, configured to controllably regulate the gas supply through the discharge aperture. In some embodiments gas may be supplied from the gas source to the discharge aperture through a compressor or a pump configured to force the gas through the discharge aperture. In some embodiments the gas of the gas source may be at ambient atmosphere, e.g. at atmospheric pressure.

In some embodiments the suction conduit may be associated with a suction pump, for providing fluid communication between the suction opening and the suction pump, thereby allowing the suction pump suck fluids from the region of plasma generation and adjoining regions through the suction opening.

Aspects and embodiments of the invention are further described in the specification hereinbelow and in the appended claims.

There is separately provided herein a plasma applicator which can be used for oral treatment of a patient.

There is separately provided herein a plasma applicator which can be used for applying a plasma-generating radio-frequency (RF) electromagnetic (EM) field.

There is separately provided herein a plasma applicator which can be used for plasma generation inside a patient mouth.

There is separately provided herein a plasma applicator which can be used for generation of direct plasma inside a patient's mouth, in a region adjoining an RF electrode of the plasma applicator and further adjoining a surface portion of the patient mouth.

Certain embodiments of the present invention may include some, all, or none of the above advantages. Further advantages may be readily apparent to those skilled in the art from the figures, descriptions, and claims included herein. Aspects and embodiments of the invention are further described in the specification hereinbelow and in the appended claims.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of conflict, the patent specification, including definitions, governs. As used herein, the indefinite articles "a" and "an" mean "at least one" or "one or more" unless the context clearly dictates otherwise.

BRIEF DESCRIPTION OF THE FIGURES

Some embodiments of the invention are described herein with reference to the accompanying figures. The description, together with the figures, makes apparent to a person having ordinary skill in the art how embodiments of the invention may be practiced. The figures are for the purpose of illustrative discussion and no attempt is made to show structural details of an embodiment in more detail than is necessary for a fundamental understanding of the invention. For the sake of clarity, some objects depicted in the figures are not to scale.

In the Figures:

FIG. 1A schematically depicts, in perspective view, an embodiment of a plasma applicator configured to generate plasma in a region adjoining a surface portion of a living body;

FIG IB schematically depicts, in cross-section view, the plasma applicator of FIG. 1 A;

FIG. 2 schematically depicts an embodiment of a plasma applicator applying a plasma generating EM field between an RF electrode of the plasma applicator and a grounded object;

FIG. 3 schematically depicts an embodiment of an RF signal generator configured to generate an RF signal at frequencies suitable for generating plasma;

FIG. 4 schematically depicts an embodiment of an RF power source, comprising the RF signal generator of FIG. 3;

FIG. 5A schematically depicts an exemplary electrical configuration configured for generating plasma in a Dielectric Barrier Discharge (DBD) mode;

FIG. 5B schematically depicts another exemplary electrical configuration configured for generating plasma in a DBD mode;

FIG. 5C schematically depicts yet another exemplary electrical configurations configured for generating plasma in a DBD mode;

FIG. 6A schematically depicts an embodiment of a plasma applicator configured to generate plasma in a Dielectric Barrier Discharge (DBD) mode in a region adjoining a surface portion of a living body;

FIG. 6B schematically depicts a manufacturing process step of an embodiment of a toroidal core of the plasma applicator of FIG. 6A, according to some embodiments;

FIG. 6C schematically depicts the plasma applicator of FIG. 6A in operation according to the teachings herein;

FIG. 7A schematically depicts an embodiment of a plasma generating apparatus comprising a mouthpiece according to the teachings herein;

FIG. 7B is a detailed view of an embodiment of a mouthpiece suitable for use together with the plasma generating apparatus of FIG. 7A;

FIG. 7C schematically depicts a cross-section of the mouthpiece depicted in FIG. 7B, and

FIG. 8 schematically depicts an embodiment of a mouthpiece suitable for use together with the plasma generating apparatus of FIG. 7A. DESCRIPTION OF SOME EMBODIMENTS

The principles, uses and implementations of the teachings herein may be better understood with reference to the accompanying description and figures. Upon perusal of the description and figures present herein, one skilled in the art is able to implement the invention without undue effort or experimentation. In the figures, like reference numerals refer to like parts throughout.

Figures 1A and IB schematically depict an embodiment of a plasma applicator 10 configured to generate plasma in a region adjoining a surface portion of a living body (not shown). Figure 1A is a perspective view, and Figure IB is a cross-section view, respectively, of plasma applicator 10.

Plasma applicator 10 comprises an electrically conducting RF electrode 12, comprising a long and thin rod 14, extending from a first end 16 to a tip 18. Tip 18 is configured to apply an RF electromagnetic field in a region of space adjoining tip 18 when EM power is supplied to RF electrode 12, and as is further explained and detailed below. In some embodiments tip 18 may be pointed or sharpened thereby enhancing the EM in the vicinity of tip 18. In some embodiments tip 18 may comprise a flat surface, thereby applying an EM field over a larger area (compared to a field applied by a pointed tip). According to some embodiments tip 18 may be shaped to apply an EM RF field over a desired surface and at a desired intensity as is known in the art of EM fields generation by RF electrodes. Rod 14 is shrouded inside a dielectric insulation 20 which extends along the side wall of rod 14 from first end 16 to tip 18, whereas first end 16 and tip 18 are not electrically insulated.

Plasma applicator 10 further comprises a tubular case 22 encasing rod 14 and dielectric insulation 20, so that rod 14 is positioned substantially along a central axis of tubular case 22. Tubular case 22 may in some embodiments be rigid or semi-rigid or flexible, so that it is not soft and may not fold or crumple spontaneously. Electrode supports 24 extend radially between tubular case 22 and dielectric insulation 20, for supporting dielectric insulation 20 and rod 14 shrouded therein substantially along the center axis of tubular case 22.

Plasma applicator 10 further comprises a gas supply conduit 30 configured to provide fluid communication between a gas inlet 32 and a gas discharge aperture 34. Accordingly, electrode supports 24 have an open structure such that allows fluid communication along gas supply conduit 30, from gas inlet 32 towards gas discharge aperture 34. In some embodiments electrode supports 24 may be rods extending between tubular case 22 and dielectric insulation 20, allowing fluid flow between the rods. In some embodiments electrode supports 24 may comprise perforated walls or sector walls, allowing fluid communication from gas inlet 32 towards gas discharge aperture 34 through the holes or through the open sectors respectively. Gas discharge aperture 34 is configured to discharge gas from gas supply conduit 30 to a region proximal to tip 18 of RF electrode 12, where plasma may be generated.

Plasma applicator 10 further comprises a suction conduit 40, configured to provide fluid communication between a suction opening 42 positioned proximal to gas discharge aperture 34, and a fluid outlet 44. In use, suction conduit 40 is configured to convey gaseous and liquid fluids from the region around suction opening 42, typically the region where plasma is generated, and surrounding regions, through suction opening 42 towards fluid outlet 44, by suction, as is detailed and explained further below. Fluids that may be sucked and conveyed by suction conduit 40 may include gas discharging from gas discharge aperture 34, plasma generated in a plasma generation region adjoining tip 18, and saliva from a patient's mouth. According to some embodiments, suction conduit 40 or a portion thereof may be flexible, enabling positioning suction opening 42 in a desired position inside the patient's mouth during use, as is known in the art of dentistry and treatment of teeth.

Plasma applicator 10 may be configured to be connected to an RF cable 50 for providing EM signal, or EM power, from an RF source (not shown) to RF electrode 12. According to some embodiments RF cable 50 may be connected to plasma applicator 10 permanently. According to some embodiments RF cable 50 may be connected to plasma applicator 10 using a connector (not shown) the connector enabling connecting and disconnecting RF cable 50 and plasma applicator 10 by a user, e.g. by hand. RF cable 50 may be any RF cable configured and suitable to conduct RF signal or RF power as is known in the art of RF transmission through RF cables, for example RG-58 coaxial cable.

Plasma applicator 10 may be further configured to be connected to a gas supply pipe 52 for conveying gas from a gas reservoir (not shown) to gas supply conduit 30. According to some embodiments gas supply pipe 52 may be connected to plasma applicator 10 permanently, thereby providing fluid communication from an end (not shown) of gas supply pipe 52 to gas discharge aperture 34 though gas supply conduit 30. According to some embodiments gas supply pipe 52 may be connected to plasma applicator 10 using a suitable connector (not shown) such as a tube connector, the connector being configured to allow fluid communication between gas supply pipe 52 and gas supply conduit 30. The connector may further be configured to enable connecting and disconnecting gas supply pipe 52 and plasma applicator 10 by a user, e.g. by hand. Gas supply pipe 52 may be a gas pipe configured and suitable to convey gas at an atmospheric pressure or at a higher pressure. Plasma applicator 10 may be further configured to be connected to a suction pipe 54 for conveying gaseous and liquid fluids from suction conduit 40 towards a suction pump (not shown). According to some embodiments suction pipe 54 may be connected to plasma applicator 10 permanently, thereby providing fluid communication from suction opening 42 though gas suction conduit 40 and suction pipe 54 towards an end (not shown) of suction pipe 54. According to some embodiments suction pipe 54 may be connected to plasma applicator 10 using a suitable fluid connector (not shown) such as a tube connector, the fluid connector being configured to allow fluid communication between suction pipe 54 and suction conduit 40. The connector may further be configured to enable connecting and disconnecting gas supply pipe 52 and plasma applicator 10 by a user, e.g. by hand. Gas supply pipe 52 may be a gas pipe configured and suitable to convey gas at an atmospheric pressure or at a higher pressure.

For plasma generation in a region of space adjoining tip 18 of RF electrode 12, RF signal at a suitable magnitude and suitable frequency may be supplied, e.g. from an RF power source to RF electrode 12 through RF cable 50. According to some embodiments, an RF power source 58 may provide the RF signal relative to ground potential, as is schematically depicted in Figure 2. Consequently, plasma applicator 10 may be used to apply an electromagnetic field in a region of space 60, substantially between RF electrode 12 and an object 62 which is positioned on the ground, to generate plasma in the region 60 in a Capacitance Coupled Plasma (CCP) mode of operation.

In CCP mode a plasma-generating EM field is applied between two electrodes, the electrodes being electrically insulated from one another. In Figure 2 a plasma generating field is applied between RF electrode 12, being a first electrode, and a surface portion of object 62, the surface potion functioning as a second electrode. A suitably selected strength of the EM field (which may be dictated by the voltage supplied to RF electrode 12 relative to ground), and a suitably selected frequency, may enable an EM field capable of ionizing the gas in region 60, to generate plasma. Plasma may consequently be generated in region 60, adjoining RF electrode 12 and object 62.

A suitable frequency may be selected so that the impedance of object 62 is lower than the impedance of the space around object 62. Such a relatively low impedance of object 62 may affect an intense EM field in the region 60, substantially between RF electrode 12 and a surface portion of object 62 closest to RF electrode 12, the field being more intense in region 60 compared to the surroundings thereof. A suitable strength of the EM field, such that may cause ionization and generate plasma in region 60, may be applied by supplying a suitable voltage to RF electrode 12 and by tuning a distance between RF electrode 12 and a surface portion of object 62 closest to RF electrode 12. The EM field strength generally increases with the voltage of RF electrode 12 (relative to a potential of object 62), and, generally, decreases with increasing the distance between RF electrode 12 and object 62. Thus, by selecting a high enough voltage supplied to RF electrode 12, and a small enough distance between RF electrode 12 and object 62, the field in region 60 may be sufficient to ionize the gas in region 60 and generate plasma. Absolute values of such voltage and distance that may affect an EM field sufficient for generating plasma may further be dependent on additional factors, for example on the geometry of tip 18 of RF electrode 12, on the geometry of object 62, particularly in a surface portion closest to RF electrode 12, on the gaseous species present in region 60 and on yet additional factors.

For use, plasma applicator 10, properly associated with an RF power source such as RF power source 58, with a gas reservoir and with a suction pump, as described above, may be employed to generate plasma in a region adjoining a living body such as a region adjoining a living human body. In some embodiments plasma applicator 10 may be employed to generate plasma in a region of space adjoining a portion of a face of a human being. According to some embodiments, plasma applicator 10 may be employed to generate plasma in a region partly or fully inside of a human's mouth. According to some embodiments, plasma applicator 10 may be employed to treat an area inside the mouth or to heal wounds or to sterilize an area inside the mouth or to whiten teeth or to conduct surface treatment of teeth, by generating plasma in a region substantially inside the mouth. Generally, when using plasma applicator 10 to generate plasma in a region adjoining a surface portion of a body such as a surface portion of a mouth, an EM field may be applied between RF electrode 12 and the surface portion, the surface portion functioning as a second electrode to the EM field, substantially as described above.

According to some embodiments of employing plasma applicator 10 for generation of plasma inside a mouth, tip 18 may be advanced and positioned at a selected distance from a surface portion selected to be treated inside the mouth. According to some embodiments, the distance between tip 18 and the surface portion to be treated, suitable for operation of plasma applicator 10, may be between about 0.1mm and about 50mm. According to some embodiments the distance may be between about 0.5mm and about 20mm. According to some embodiments the distance may be between about 1mm and about 10mm. According to some embodiments the distance may be about 2mm or about 5mm or about 8mm. According to some embodiments an EM signal may be supplied by an RF power source to RF electrode 12 for application of an EM field between RF electrode 12 and a surface portion of the mouth. According to some embodiments a frequency of the EM signal may be in a range between about lOOKHz and about 100MHz. According to some embodiments the frequency may be between about 100MHz and 10GHz According to some embodiments the frequency may be between about 500KHz and 50MHz. According to some embodiments the frequency may be between about lMHz and 15MHz. According to some embodiments the frequency may be about 2MH, or about 5MHz or about 10MHz or about 13MHz.

According to some embodiments a voltage supplied to RF electrode 12 sufficient to affect a plasma-generating field may be in a range between about 100V and about 10KV. According to some embodiments the voltage may be between 500V and 5KV. According to some embodiments the voltage may be between about 700V and about 2.5KV. According to some embodiment the voltage supplied to RF electrode 12 may be tuned according to the distance between tip 18 and the surface portion of the mouth closest to tip 18. According to some embodiments the ratio of voltage to distance is in a range between lOOV/mm and lOOOV/mm.

According to some embodiments suction opening 42 may be positioned in the region of plasma generation by plasma applicator 10, or in an adjoining region, namely proximal to where plasma may be generated. According to some embodiments, suction opening 42 may be positioned inside the mouth of a patient so that saliva may be sucked through suction opening 42 thereby assisting in maintaining the treated area substantially dry, and/or avoiding the accumulation of unswallowed saliva in the patient's mouth.

In operation, a suction pump, associated with suction pipe 54 and with suction opening 42 through suction conduit 40, may be activated to affect suction of fluids from the patient's mouth. An RF power source such as RF power source 58 may be activated to supply an RF signal at a desired magnitude and frequency to RF electrode 12, to apply a plasma-generating field substantially between tip 18 and a surface portion of the patient's mouth. Gaseous species which are generated in the plasma generation region may apply a desired effect on a surface portion of the mouth, such effect may be wounds healing and/or sterilizing a wound or a surface area or a portion of a tooth, and/or whitening a tooth or a portion thereof. Such gaseous species may be sucked through suction opening 42 soon after being generated in the plasma generation region, thereby assisting in limiting the affects of active gaseous species to a limited region in the mouth. According to some embodiments a desired gas or a desired mix of gases may be discharged through gas discharge aperture 34, to obtain a desired combination of gases in the plasma generation region. According to some embodiments one or more inert gases such as helium or argon may be included in a gas discharged from gas discharge aperture 34 during plasma generation.

According to an aspect of some embodiments, the RF signal provided to RF electrode 12 for applying a plasma generating field may be modulated. According to some embodiments the modulation signal may include pulse modulation. According to some embodiments, the modulation signal may include amplitude modulation. According to some embodiments the modulation signal may include a combination of types of modulation. Figure 3 depicts schematically an embodiment of an RF signal generator 70, configured to generate an RF signal at frequencies suitable for generating plasma. RF signal generator 70 comprises an RF continuous wave (CW) source 72 configured to generate a carrier RF signal 100, and a pulse generator 74 configured to generate a modulation signal 102. RF signal generator 70 further comprises an RF mixer 76 functionally associated with RF CW source 72 and with pulse generator 74, and configured and operable to output a modulated RF signal substantially as described herein below. Carrier RF signal 100 includes a continuous wave (CW) signal substantially at a frequency suitable for plasma generation as described above. Modulation signal 102 comprises a repetitive pattern 104 of pulses comprising a first modulation pulse 106 at an amplitude Al of about 4V and pulse width PW1 of about 10 microseconds (usee), and a second modulation pulse 108, starting about 0.4usec after first modulation pulse 106 ends, at an amplitude A2 smaller than Al of IV and a pulse width PW2 greater than PW1 of about 120 usee. Repetitive pattern 104 may cyclically repeat at a pulse repetition interval (PRI) of about 2msec. Parameters of repetitive pattern 104, including the pulse widths values PW1 and PW2, pulse amplitudes Al and A2, the time interval between the pulses and the PRI of repetitive pattern 104 specified above, are provided by way of a non-limiting example, and other parameters, including other pulse widths, a different interval between the pulses, combinations of more than two pulses in a single repetitive pattern and even modulations of a carrier signal that are not purely repetitive, are all contemplated herein.

Modulation signal 102 is mixed with carrier RF signal 100 in RF mixer 76 to generate a modulated RF signal 110 having suitable frequencies and time dependency for applying a plasma-generating EM field, when supplied to RF electrode 12. Modulated RF signal 110 is generally characterized with a first relatively high amplitude and short period ignition pulse 112, associated with first modulation pulse 106, followed by a relatively lower amplitude, longer period work pulse 114, associated with second modulation pulse 108. Ignition pulse 112 is configured to be strong enough (that is to say, of high enough intensity) to generate plasma in an initially nonionic gas in the region adjoining RF electrode 12, e.g. by inducing a sufficient number of ionized atoms and molecules, and a corresponding number of free electrons, for plasma generation. Work pulse 114 is configured to maintain the plasma generation process after plasma has been ignited by ignition pulse 112, and may therefore have a lower amplitude than ignition pulse 112. Maintaining the plasma generation does not necessitate work pulse 114 to have a lower amplitude than ignition pulse 112. However, according to some embodiments it may be advantageous to maintain a plasma generation process by applying the lowest possible EM field. Thus, according to some embodiments it is advantageous to ignite plasma with a relatively strong ignition EM field and, subsequently, maintaining the plasma with a relatively weaker EM field.

Figure 4 schematically depicts an embodiment of RF power source 58. RF power source 58 comprises RF signal generator 70 and an amplitude controller 80 functionally associated with RF signal generator 70 to receive modulated RF signal therefrom. RF power source 58 further comprises an RF amplifier 82 functionally associated with amplitude controller 80. RF amplifier 82 is configured to amplify modulated RF signals received from amplitude controller 80 and provide RF power to a load 84 configured to consume RF power, such as RF electrode 12. RF power source 58 further comprises a load monitor 86, functionally associated with RF amplifier 82 and/or with load 84. Load monitor 86 is configured to provide an electronic signal indicating one or more characteristics of load 84 and/or one or more characteristics of the RF power supplied to load 84. For example, load monitor 86 may be employed to monitor a momentary impedance of load 84. Additionally or alternatively load monitor 86 may be configured to monitor or sense a characteristics of the RF power signal delivered to load 84. For example, load monitor 86 may be employed to monitor the current consumed by load 84 and/or the voltage across load 84 and/or the total power consumed by load 84 etc. Amplitude controller 80 is functionally associated with load monitor 86 for receiving the electronic signal indicating load 84 characteristics, thereby enabling a feedback loop for compensating variations in characteristics of load 84. Amplitude controller 80 is configured to regulate the amplitude of the modulated RF signal provided to RF amplifier 82 for amplification, according to the electronic signal from load monitor 86. For example, according to some embodiments, if load monitor 86 monitors or senses a decrease in the impedance of load 84, potentially leading to an increase in power consumption by load 84, amplitude controller 80 may consequently decrease the voltage of the modulated RF signal provided to RF amplifier 82, thereby preventing or at list reducing a change in RF power consumption by load 84. When applying a plasma-generating EM field in close proximity to a body, e.g. a human body, in an attempt to generate non-thermal plasma in a region adjoining the body, precaution may be taken to one or more aspects of the plasma generating field and to the plasma generation process. One such aspect is the power dissipation in the plasma generation region, whereas it may be desired to maintain the dissipated power below a pre-determined value. The power dissipated in the plasma generation region by the plasma generating EM field is transformed into heat that increases the gas temperature in the plasma generation region. To prevent such an undesired temperature increase, EM power delivery to RF electrode 12 may be controlled and limited. The EM power may be limited e.g. by limiting the voltage of modulated RF signal supplied to RF electrode 12, or by limiting the RF current through RF electrode 12 (that is to say, substantially the charge carriers current in the plasma, generated by the plasma generating EM field).

Another aspect of the plasma generation process may be the mode of operation, or work regime of the plasma. Specifically, it may be desired to maintain the plasma at a glow regime and to prevent an occurrence of an electric arc. An electric arc between RF electrode 12 and the body (as a surface portion of the body being employed as a second electrode for the plasma generating EM field) may cause burns to the body at a point where the arc hits the body, and may further heat up the plasma to an intolerable or undesirably high temperature. Moreover, when employing a plasma applicator such as plasma applicator 10 in a vicinity of a tooth, for example during a procedure of teeth whitening, an accumulation of RF current through the tooth, for example if an arc hits the tooth, may cause irreversible damage to the root of the tooth. Thus, to prevent such an undesired electric arc, the voltage of the modulated RF signal supplied to RF electrode 12 may be controlled and limited. For example, a transformation of the plasma generation process form a glow regime to an arc regime may be accompanied by a generation of a relatively highly conductive channel in the ionized gas in an avalanche process, which is further characterized by a quick drop in the impedance of load 84 and a related increase in RF current and RF power consumed by load 84. An arc may be prevented by a swift decrease in the supplied voltage, in response to a quick drop in the impedance of load 84, thereby decreasing the RF plasma-generating EM field, before the conductive channel enabling the arc is fully formed in the ionized gas. According to some embodiments, fully eliminating the RF plasma-generating EM field by reducing to zero the RF power supplied to RF electrode 12, (load 84) may be employed, to prevent the occurrence of an arc.

Thus, by monitoring characteristics of load 84 by load monitor 86, e.g. by monitoring characteristics of the power consumed by load, the feedback loop incorporating load monitor 86 and amplitude controller 80 may be employed to compensate variations in load characteristics by related EM field variations, to maintain the plasma in a desired mode of operation.

According to some embodiments load monitor 86 is configured to monitor one or more characteristics of load 84 or one or more characteristics of the electric power delivered from RF amplifier 82 to load 84, or a combination thereof. For example, according to some embodiments load monitor 86 may monitor the total momentary power consumed by RF electrode 12. Upon sensing an increase in consumed power beyond a pre-determined value, load monitor 86 may output an electronic signal indicating amplitude controller 80 to decrease the amplitude of the modulated RF signal supplied to RF amplifier 82. According to some embodiments, load monitor 86 may sense the total momentary power supplied to load 84 e.g. by measuring the RF voltage and RF current through RF electrode 12 (substantially, through load 84). Additionally or alternatively load monitor 86 may sense the power delivered by sampling the power delivered to load 84, e.g. using a coupler employed to consume a pre- defined percentage of the power delivered to load 84. According to some embodiments load monitor 86 may be configured to measure a Standing Wave Ratio (SWR) in the RF transmission line delivering the RF power from RF amplifier 82 to load 84, thereby monitoring variations of the impedance of load 84 and/or variation in impedance matching between load 84 and the RF transmission line which provides the RF power to load 84. According to some embodiments, load monitor 86 may be configured to measure a Voltage SWR (VSWR). Load monitor 86 may alternatively or additionally employ any technique known in the art to sense a load characteristics, in order to monitor characteristics of load 84 (namely, characteristics of RF electrode 12, in operation) or to monitor characteristics of the power signal delivered thereto.

According to some embodiments a Dielectric Barrier Discharge (DBD) mode of operation may be selected for generating plasma in a region adjoining a body surface portion. In a DBD mode of operation two electrodes are employed for applying an EM field, as in a CCP mode of operation. A body surface portion may function as one of the two electrodes, as described above regarding CCP mode of operation. A dielectric barrier, positioned substantially between the two electrodes, is employed to prevent occurrence of an arc or a spark in the gas between the two electrodes, or at least to diminish the likelihood of such an arc or a spark. Figures 5A - 5C schematically depict three exemplary configurations, respectively, configured for generating plasma in a DBD mode. First configuration 150, depicted in Figure 5 A, comprises an RF source 152 associated, with inverse polarity, respectively, with electrodes 154 and 156, to apply a plasma generating field therebetween. A single dielectric layer 160, functioning as a dielectric barrier, is positioned between electrode 154 and electrode 156, attached to electrode 154. Second configuration 162, depicted in Figure 5B, comprises an RF source 152 associated with electrodes 154 and 156, to apply a plasma generating field therebetween. A single dielectric layer 160, functioning as a dielectric barrier, is positioned between electrode 154 and electrode 156, not attaching neither of the two electrodes. Third configuration 164, depicted in Figure 5C, comprises an RF source 152 similarly associated with electrodes 154 and 156. Two dielectric layers 160a and 160b, separated from each other, are positioned between electrode 154 and electrode 156, so that dielectric layer 160a is attached to electrode 154 and dielectric layer 160b is attached to electrode 156.

Figure 6A schematically depicts an embodiment of a plasma applicator 200, configured for applying a plasma-generating EM field in a DBD mode of operation. Plasma applicator 200 comprises an RF electrode 202 comprising a cord 204 having an electrically conducting wire (not shown) shrouded inside an electric insulation layer along the wire's length. Cord 204 is wound around a toroidal core 206 arranged inside a tubular case 210 so that an axis of revolution of toroidal core 206 substantially coincides with an axis of symmetry of tubular case 210. According to some embodiments, toroidal core 206 may have an O-ring shape, as a torus generated by a circle revolved around the axis of revolution of the torus. According to some embodiments toroidal core 206 may have a shape of a pipe, as a hollow cylinder generated by a rectangle revolved around the axis of revolution of the toroid, as is depicted in Figure 6A. Toroidal core 206 may be produced from a substantially non-magnetic, electrically insulating material such as plastic or glass. According to some embodiments, RF electrode 202 may be manufactured by wounding cord 204 around a rectangular layer 208a of firm and flexible material such as plastic, as is schematically depicted in Figure 6B. The wounding may be carried out progressively from one end 208b of rectangular layer 208a to an opposite end 208c thereof. Following wounding, rectangular layer 208a may be rolled so as to coincide and adjoin one end 208b with opposite end 208c, thereby forming toroidal core 206 with cord 204 wounded thereon. The electrically conducting wire of cord 204 may be electrically connected to RF cable 50 for providing EM signal, or EM power, from an RF source (not shown) to RF electrode 202. The electrically conducting wire of cord 204 may be electrically connected to RF cable 50 at any one of the two ends of cord 204, or at both ends of cord 204 (as is schematically depicted in Figure 6B).

Tubular case 210 may in some embodiments be rigid or semi-rigid or flexible, so that tubular case 210 is not soft and may not fold or crumple spontaneously. Electrode supports 214 extend radially between tubular case 210 and toroidal core 206, for supporting toroidal core 206 inside tubular case 210. Substantially similarly to plasma applicator 10, plasma applicator 200 comprises gas supply conduit 30 configured to provide fluid communication between gas inlet 32 and gas discharge aperture 34. Accordingly, electrode supports 214 have an open structure such that allows fluid communication along gas supply conduit 30, from gas inlet 32 towards gas discharge aperture 34. In some embodiments tubular case 210 may function as gas supply conduit 30, as is schematically depicted in Figure 6B, and electrode supports 214 may be rods extending between tubular case 210 and toroidal core 206, allowing fluid flow between the rods. In some embodiments electrode supports 214 may comprise perforated walls or sector walls, allowing fluid communication from gas inlet 32 towards gas discharge aperture 34 through the holes or through the open sectors respectively. In some embodiments, substantially similarly to plasma applicator 10, plasma applicator 200 may comprise a suction conduit 220 configured to convey gaseous and liquid fluids from the region where plasma is generated, and from surrounding regions, through a suction opening 222, and through suction conduit 220 towards a suction pump (not shown), by suction, substantially as is detailed and explained above regarding plasma applicator 10.

Plasma applicator 200 further comprises an aerosol injector 230 configured to inject aerosol containing a desired mix of chemicals to the plasma generation region. Aerosol injector 230 comprises an aerosol conduit 232 having on one end thereof an aerosol inlet 234 and on another end thereof at least one aerosol spout 236. Aerosol inlet 234 is configured to be associated, directly or through a pipe such as a flexible pipe, with an aerosol source such as a pressurized container containing the aerosol or containing a liquid form thereof. Aerosol spout 236 may be configured to spray aerosol or to discharge aerosol substantially to the region where plasma is generated by plasma applicator 200. Aerosol conduit 232 is configured to provide fluid communication between aerosol inlet 234 and aerosol spout 236, and to withstand a pressure suitable for use in generating and injecting aerosol, e.g. a pressure between about latm. and about lOatm., for example a pressure of about 5 atmospheres. In use, aerosol injector may be operated to inject aerosol comprising oxidizers such as H2O2 or - OH that in some embodiments may assist or expedite a teeth bleaching process.

It is noted that aerosol injector 230 is described herein in conjunction with plasma applicator 200 in an exemplary, non-limiting manner, and an aerosol injector having a substantially similar functionality may be included in other plasma applicators according to the teachings herein. For example, in some embodiments of plasma applicator 10, rod 14 of RF electrode 12 may be hollow, having a shape of a pipe, thereby providing fluid communication between e.g. first end 16 and tip 18. Tip 18, being hollow, may function as an aerosol spout, so that aerosol may be pressurized through a hollow rod 14 and injected towards the plasma generation region through a hollow tip 18. An aerosol injector is thus contemplated with any plasma applicator according to the present invention.

Figure 6C schematically depicts an image of an embodiment of plasma applicator 200 in operation. By applying an RF EM field at a suitable strength between RF electrode 202 and a grounded object 240, plasma is generated in a region 242 adjoining RF electrode 202 and grounded object 240, as is indicated by the glow in region 242.

Generally, the type of plasma applicator selected to apply an EM field for generation of plasma, may affect the characteristics of the EM field that are suitable for such plasma generation. For example, a plasma applicator such as plasma applicator 10, having an electrically exposed tip 18 may require a lower voltage for plasma ignition and for maintaining the gas ionization process, compared to a plasma applicator such as plasma applicator 200, which is configured to operate in a DBD mode. Generally, a plasma applicator having the RF electrode thereof electrically isolated may require a higher RF voltage compared to a plasma applicator having an electrically exposed RF electrode, under similar operating conditions (similar atmosphere, similar object to which the plasma generation region adjoins, similar distance between the electrode and the object, etc.).

According to some embodiments an apparatus for generating plasma according to the teachings herein may comprise an RF power source for providing RF power for plasma generation, as is described herein above. The RF power source may be configured to functionally associate with any desired one of several plasma applicators, the plasma applicators being substantially different from one another and configured to generate plasma in different modes of operation or near different regions of a patient's body, or to obtain different treatment results. For example, such an apparatus for generating plasma may be configured to operate with a plasma applicator such as plasma applicator 10 in one operational mode, for generating plasma in a CCP mode of operation, and alternatively to operate with a plasma applicator such as plasma applicator 200 in another operational mode, for generating plasma in a DBD mode of operation.

According to some embodiments the apparatus for plasma generation may be configured to recognize the type of plasma applicator which is associated with the RF power source by a user. According to some embodiments plasma applicators of different types have different keys associated with a connector connecting the plasma applicator to the apparatus. Thus, when a plasma applicator is connected to be associated with the RF power source, the key may provide an indication to the apparatus on the type of the plasma applicator.

According to some embodiments the apparatus for plasma generation may recognize the type of plasma applicator associated with the RF power source by analyzing the characteristics of power consumption during plasma generation. Typically, for example, ignition of plasma is accompanied by a drop in the load impedance and consequently by an increase in power consumption (e.g. increase in current consumption if the voltage of the RF electrode remains constant). In some embodiments, the voltage and current after plasma ignition may indicate the type of plasma applicator being used. For example, a low voltage and high current when operating a first plasma applicator, compared to a high voltage and low current when operating a second plasma applicator may indicate that the first plasma applicator is similar to plasma applicator 10 having an electrically exposed RF electrode, whereas the second plasma applicator is similar to plasma applicator 200 having an electrically isolated RF electrode.

According to some embodiments the apparatus for plasma generation may recognize a type of body portion adjoining which plasma is being generated. For example, the apparatus may recognize generation of plasma in a region adjoining a tooth from generation of plasma in a region adjoining the tongue. According to some embodiments the apparatus may further recognize generation of plasma in a region adjoining a body portion from generation of plasma in a region that does not adjoin a body (namely generating plasma in the air around the RF electrode). For example, analyzing characteristics of the RF power consumed during operation may be employed to recognize plasma generation near one body portion from another body portion. For example, a low voltage and high current may indicate plasma generation in a region adjoining a soft tissue such as a tongue, whereas high voltage and low current may indicate plasma generation in a region adjoining a hard tissue such as a tooth. Yet higher voltage and lower current may indicate generation of plasma in the air. Likewise, relatively high power consumption may indicate plasma generation in a region adjoining a soft tissue, lower power consumption may indicate plasma generation in a region adjoining a hard tissue, and still lower power consumption may indicate plasma generation in air.

Figure 7A schematically depicts an embodiment of an apparatus for plasma generation

280 comprising a plasma applicator 300 configured to generate plasma in regions adjoining one or more teeth of a patient. Plasma applicator 300 comprises a mouthpiece 302 made of a tough and flexible material, suitable for being used inside a patient's mouth. Exemplary materials suitable for use for mouthpiece 302 may comprise silicone, polypropylene(PP), polyethylene(PE) and latex. Mouthpiece 302 has a general U shape, fitting in size and configured to be held in a patient's mouth between the teeth of the lower jaw and the teeth of the upper jaw so that the U shape generally fits the shape and curvature of the jaws. Plasma applicator 300 comprises RF electrodes 304 (not shown in this Figure) embedded in mouthpiece 302. Each RF electrode terminates at a tip 306, configured to apply a plasma- generating EM field in a region adjoining a tooth of a patient, as is further described and explained below. Mouthpiece 302 is configured to be connected to an RF cable 312, RF cable 312 being configured to deliver EM signal or EM power from a power source 314 to RF electrodes 304. Mouthpiece 302 is further configured to connect to a gas supply pipe 316 for supplying gas from a gas reservoir 318 to gas discharge apertures 320 in mouthpiece 302. Mouthpiece 302 is further configured to connect to a suction pipe 322 for sucking gaseous and liquid fluids from a patient's mouth to a suction pump 324, by suction. RF cable 312, gas supply pipe 316 and suction pipe 322 may, in some embodiments, be encased together in a single combo cable 326. In some embodiments combo cable 326 may extend during operation from an operation rack comprising suction pump 324, power source 314 and a gas reservoir 318, to mouthpiece 302 inside a patient's mouth. According to some embodiments a flow sensor (not shown in this Figure) may be employed to estimate the flow inside suction pipe 322 during operation. According to some embodiments, the flow sensor may be functionally associated with power source 314 and configured to interrupt operation of RF source upon a suitable command. According to some embodiments, the flow sensor may be configured to interrupt operation of power source 314 when fluid flow in suction pipe 322 decreases below a predetermined threshold. According to some embodiments, the flow sensor may be configured to interrupt operation of power source 314 when fluid flow in suction pipe 322 decreases below a pre-determined threshold or blocked for a time period that extends beyond a pre-determined threshold. According to some embodiments, plasma applicator 300 may be configured to stop plasma generation if suction through suction pipe 322 is blocked.

Figure 7B schematically depicts a detailed view of mouthpiece 302 and Figure 7C schematically depicts mouthpiece 302 in cross-section view. Mouthpiece 302 is configured to be held during operation in a patient's mouth between the lower jaw and the upper jaw as the patient fastens the jaws against mouthpiece 302. Mouthpiece 302 comprises an upper bite surface 330 and a lower bite surface (332 in Figure 7C) having a U shape universally adjusted to dimensions and curvature of a person's jaws and configured to be held between the jaws of a patient when the patient fastens the jaws against mouthpiece 302. An upper electrode support wall 336 extends upwards from upper bite surface 330 on the outer rim of the U of upper bite surface 330. Likewise, a lower electrode support wall 340 extends downwards from the lower bite surface on the outer rim of the U of the lower bite surface. In some embodiments mouthpiece 302 may further comprise an inner upper wall 338 and an inner lower wall 342 extending upwards and downwards, respectively, from upper bite surface 330 and from the lower bite surface, respectively, on the inner rim of the U. The inner upper wall and inner lower wall are configured to be substantially supported on the inner side of the teeth of the patient when mouthpiece 302 is held between the jaws, thereby assisting in stabilizing mouthpiece 302 between the jaws and preventing accidental or undesired sliding of mouthpiece 302 during operation.

RF electrodes 304a are arranged along upper electrode support wall 336 and RF electrodes 304b are arranged along the lower electrode support wall. According to some embodiments mouthpiece 302 comprises several RF electrodes wherein tips 306 point towards the patient's teeth. According to some embodiments mouthpiece 302 comprises a number of RF electrodes equal to the number of teeth of an adult human being whereas RF electrodes 304 are arranged and positioned along upper electrode support wall 336 and along the lower electrode support wall so that each tip 306 faces a single tooth. Thus, according to some embodiments, each electrode may apply a relatively local plasma-generating EM field in a region adjoining that electrode and further adjoining the tooth that the tip of the electrode faces.

Each RF electrode 304 comprises an electric conductor terminating at tip 306 configured to apply an RF EM field over a desired surface and at a desired intensity as is known in the art of EM generation by RF electrodes and as is explained above regarding tip 18 of plasma applicator 10. Each tip 306 may in some embodiments terminate at about a plane that coincides with the surface, around tip 306, of the electrode support wall which supports the tip, namely upper electrode support wall 336 or the lower electrode support wall. RF electrodes 304 are electrically interconnected by an electric conductor 308 so that RF electrodes 304 are at a same electric potential during operation. According to some embodiments tips 306 are electrically insulated, thereby being configured to operate in a DBD mode of operation. In some embodiments tips 306 are electrically exposed.

Mouthpiece 302 comprises a gas supply conduit 344, providing fluid communication between a gas supply inlet 346 (Shown in Figure 7A) and the multitude of gas discharge apertures 320. During operation, gas supply pipe 316 is associated with gas supply inlet 346. Gas may thus be supplied from gas reservoir 318 through gas supply pipe 316 and gas supply conduit 344 to be distributed to the multitude of gas discharge apertures 320. Each tip 306 is positioned substantially in a center of a gas discharge aperture 320, gas discharge apertures 320 being thereby configured to discharge gas supplied from gas reservoir 318 to the regions where plasma may be generated during operation, adjoining tips 306. According to some embodiments, RF electrodes 304 are substantially insulated electrically, except, in some embodiments, around tip 306. In other words, in some embodiments tip 306 may be insulted so that RE electrodes 304 and tips 306 are entirely insulated from the outside world. In some embodiments tips 306 may be electrically exposed. Electric insulation to RF electrodes 304 may be provided by the bulk of mouthpiece 302, along such segments of the RF electrodes that are entirely embedded inside mouthpiece 302. Each RF electrode 304 may protrude from the bulk of mouthpiece 302 into an associated segment of gas supply conduit 344, possibly in the vicinity of an associated tip 306, as is schematically illustrated in Figure 7B. A segment of an RF electrode 304 (and/or a segment of electrical conductor 308) protruding from the bulk of mouthpiece 302 and extending along a segment of gas supply conduit 344 may be insulted by suitable shroud of an insulting material as is known in the art of insulted electrical conductors and electrical wires.

Mouthpiece 302 further comprises a suction conduit 350 providing fluid communication between suction openings 352 positioned on upper bite surface 330 and on the lower bite surface, and a fluid outlet 354. During operation fluid outlet 354 is associated with suction pipe 322 so that fluids such as saliva and gaseous species may be sucked from the patient's mouth through suction openings 352, suction conduit 350 and suction pipe 322 by suction pump 324.

Mouthpiece 302 further comprises gingival seals 360. One or more gingival seals 360a are arranged along upper electrode support wall 336 on an inner side thereof, substantially above RF electrodes 304, facing the upper gingiva when mouthpiece 302 is held between the jaws. One or more gingival seals 360b are arranged along the lower electrode support wall on an inner side thereof, substantially below RF electrodes 304b, facing the lower gingiva when mouthpiece 302 is held between the jaws. In some embodiments a gingival seal 360 may comprise a suction cup, enabling to attach upper electrode support wall 336 and the lower electrode support to the upper and lower gingiva, respectively. In some embodiments a gingival seal 360a may comprise a soft and long protrusion protruding from upper electrode support wall 336 towards the upper gingiva and extending along the top end of upper electrode support wall 336 substantially from one side to an opposite side. Likewise, a gingival seal 360b may comprise a soft and long protrusion protruding from the lower electrode support wall towards the lower gingiva and extending along the bottom end of the lower electrode support wall substantially from one side to an opposite side thereof. According to some embodiments Gingival seals 360 are employed to substantially seal off an active volume 362, namely a region wherein plasma is generated, between upper electrode support wall 336 and the teeth of the upper jaw and between the lower electrode support wall and the teeth of the lower jaw, from the rest of the internal volume of the mouth. In operation, gas from gas reservoir 318 is discharged into the active volume through gas discharge apertures 320 and active species are generated in the active volume as a result of the plasma being generated therein. The gas and the active species may potentially have an undesired effect on the patient, if they spread outside the active volume. For example an active species that may be abundant in the active region due during plasma generation is ozone (03), which may be dangerous to a patient if inhaled to the lungs in high concentrations. The gas and active species may be sucked through suction openings 352 by suction pump 324, thereby being removed from the active region, whereas gingival seals 360 further prevent or at least minimize leakage of such gas and active species from the active region to the mouth, thereby assisting in preventing detrimental effects of such gas and active species to the patient.

In some embodiments mouthpiece 302 further comprises ventilation channels 370, enabling fluid communication from the external side of mouthpiece 302 to the internal side thereof. During operation, as mouthpiece 302 is held between the jaws of the patient and the jaws are substantially fastened onto mouthpiece 302, breathing through the mouth may be enabled for the patient through ventilation channels 370, thereby removing a necessity that might be unpleasant to some patients, to breath through the nose during the treatment time.

Figure 8 schematically depicts a plasma applicator 400 comprising a mouthpiece 402. Mouthpiece 402 is different from mouthpiece 302 in having elongated RF electrodes 404 comprising an elongated RF electrode 404a arranged along upper electrode support wall 336 and an elongated RF electrode 404b (not shown in this Figure) arranged along the lower electrode support wall. RF electrodes 404 are configured to apply a plasma generating EM field in a relatively large region, adjoining several teeth. In some embodiments a single elongated RF electrode 404a may apply a plasma-generating EM field in a region substantially adjoining all the teeth in the upper jaw during operation. Likewise, a single elongated RF electrode 404b may apply a plasma-generating EM field in a region substantially adjoining all the teeth in the lower jaw during operation.

There is thus provided according to an aspect of some embodiments a plasma applicator (10, 200, 300, 400) configured to generate non-thermal plasma in a region adjoining a surface portion of a living body. The plasma applicator comprises one or more electrically conducting electrodes (12, 202, 304, 404) configured to apply an electromagnetic (EM) field suitable for ionizing gas at atmospheric pressure for generation of plasma in at least one region adjoining the electrodes and adjoining the surface portion of the living body. The plasma applicator further comprises a gas supply conduit (30, 344) having at least one gas discharge aperture (34, 320) configured to discharge gas from the gas supply conduit to at least one region of plasma generation. The plasma applicator further comprises a suction conduit (40, 220, 350) having at least one suction opening (42, 222, 352), configured to covey gaseous and liquid fluids from the region of plasma generation and adjoining regions through the suction opening, by suction.

According to some embodiments the electrode (12) is shaped as a tip (18) located in the gas discharge aperture (34) so that the gas is discharged from the discharge aperture around the tip.

According to some embodiments the electrode (202) comprises an elongated electric conductor (204) wound around a toroidal core (206). According to some embodiments the toroidal core is located in the discharge aperture (34) so that the gas is discharged from the gas discharge aperture around the toroidal core. According to some embodiments the elongated conductor is a cord comprising an insulated electrical wire.

According to some embodiments the plasma applicator further comprises an aerosol injector (230) configured to inject aerosol to the plasma generation region According to some embodiments the aerosol injector comprises an aerosol spout (236) shaped as a hollow tip and located in the gas discharge aperture so that the gas is discharged from the gas discharge aperture around the hollow tip.

According to some embodiments the plasma applicator (300, 400) comprises several electrodes (304, 404) for plasma generation, the electrodes being electrically inter-connected.

According to some embodiments the plasma applicator (300, 400) further comprises a mouthpiece (302, 402) configured to be held in a patient's mouth. According to some embodiments the mouthpiece has a general U shape, configured to be held between the teeth of the lower jaw and the teeth of the upper jaw of the patient.

According to an aspect of some embodiments there is further provided an apparatus (280) for generation of non-thermal plasma for oral treatment, comprising a plasma applicator (10, 200, 300, 400) configured to generate non-thermal plasma in a region adjoining a surface portion of a living body. The apparatus further comprises a cable 312 for providing EM power to the electrode (12, 202, 304, 404) of the plasma applicator. The apparatus further comprises a gas supply pipe (316) for conveying gas to the gas supply conduit (30, 304), and a suction pipe (322) for conveying gaseous and liquid fluids from the suction conduit (40, 220, 350) towards a suction pump (324). According to some embodiments the apparatus further comprises a power source (58, 314) functionally associated with the electrode for supplying to the electrode EM signal suitable for applying a plasma generating EM field. According to some embodiments the cable is an RF cable and the EM power source is an RF power source configured to supply EM power at a frequency in a range between lOOKHz and 100MHz.

According to some embodiments the EM signal (110) is modulated by pulses. According to some embodiments the EM signal is modulated by a repetitive pattern comprising an ignition pulse (112) followed by a work pulse (114) wherein the ignition pulse has a pulse width PW1 and an amplitude Al and the work pulse has a pulse width PW2>PW1 and an amplitude A2<A1. According to some embodiments the plasma generating EM field is between about lOOV/mm and about lOOOV/mm. According to some embodiments a voltage supplied to the electrode for applying the plasma generating EM field is between about 500V and about 5KV.

According to some embodiments the power source comprises a load monitor (86) configured for monitoring a characteristic of the EM signal delivered to the electrode, the power source being thereby configured to regulate a voltage or a current or a total power supplied to the electrode.

According to some embodiments the apparatus further comprises a gas reservoir (318) functionally associated with the gas pipe (316). According to some embodiments the apparatus further comprises a suction pump (324) functionally associated with the suction pipe (322).

According to a further aspect of some embodiments there is provided a method for providing oral treatment in a treatment site on a surface portion of a mouth of a patient. The method comprises providing the apparatus (280) described above and advancing the plasma applicator (10, 200, 300, 400) to the treatment site so that at least one electrode (12, 202, 304, 404) of the plasma applicator is proximal to the surface portion of the mouth. The method further comprises supplying EM power from the power source (58, 314) to the electrode, thereby exciting plasma in a region adjoining the electrode and adjoining the surface portion of the mouth of the patient.

According to some embodiments the method further comprises releasing gas from the gas discharge aperture (34, 320) in the region of plasma excitation. According to some embodiments the oral treatment comprises teeth bleaching, and the surface portion of the body comprises a tooth. It is noted that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

Although the invention is described in conjunction with specific embodiments thereof, it is evident that alternatives, modifications and variations should be apparent to those skilled in the art. Accordingly, the invention is intended to embrace all such alternatives, modifications and variations that fall within the scope of the appended claims.

Citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the invention.

Section headings are used herein to ease understanding of the specification and should not be construed as necessarily limiting.

Claims

A plasma applicator configured to generate non-thermal plasma in a region adjoining a surface portion of a living body, said plasma applicator comprising:

one or more electrically conducting electrodes configured to apply a radio- frequency (RF) electromagnetic (EM) field suitable for ionizing gas at atmospheric pressure for generation of plasma in at least one region adjoining said electrodes and adjoining said surface portion of the living body;

a gas supply conduit having at least one gas discharge aperture configured to discharge gas from said conduit to at least one region of plasma generation, and a suction conduit having at least one suction opening, configured to covey gaseous and liquid fluids from the region of plasma generation and adjoining regions through said suction opening, by suction.

The plasma applicator of claim 1 wherein said electrode is shaped as a tip located in said gas discharge aperture so that said gas is discharged from said discharge aperture around said tip.

The plasma applicator of claim 1 wherein said electrode comprises an elongated electric conductor wound around a toroidal core.

The plasma applicator of claim 0 wherein said toroidal core is located in said discharge aperture so that said gas is discharged from said gas discharge aperture around said toroidal core.

The plasma applicator of claim 0 wherein said elongated conductor is cord comprising an insulated electrical wire.

The plasma applicator of claim 1 further comprising an aerosol injector configured to inject aerosol to the plasma generation region.

The plasma applicator of claim 0 wherein said aerosol injector comprises an aerosol spout shaped as a hollow tip and located in said gas discharge aperture so that said gas is discharged from said gas discharge aperture around said hollow tip.

The plasma applicator of claim 1 comprising several electrodes for plasma generation, said electrodes being electrically inter-connected.

9. The plasma applicator of claim 1 further comprising a mouthpiece configured to be held in a patient's mouth.

10. The plasma applicator of claim 0 wherein said mouthpiece has a general U shape, configured to be held between the teeth of the lower jaw and the teeth of the upper jaw of the patient.

11. An apparatus for generation of non-thermal plasma for oral treatment comprising a plasma applicator configured to generate non-thermal plasma in a region adjoining a surface portion of a living body, said plasma applicator comprising:

one or more electrically conducting electrodes configured to apply an electromagnetic (EM) field suitable for ionizing gas at atmospheric pressure for generation of plasma in at least one region adjoining said electrodes and adjoining said surface portion of the living body;

a gas supply conduit having at least one gas discharge aperture configured to discharge gas from said gas supply conduit to at least one region of plasma generation, and

a suction conduit having at least one suction opening, configured to covey gaseous and liquid fluids from the region of plasma generation and adjoining regions through said suction opening, by suction,

and said apparatus further comprises

a cable for providing EM power to said electrode;

a gas supply pipe for conveying gas to said gas supply conduit, and a suction pipe for conveying gaseous and liquid fluids from said suction conduit towards a suction pump.

12. The apparatus of claim 0 further comprising a power source functionally associated with said electrode for supplying to said electrode EM signal suitable for applying a plasma generating EM field.

13. The apparatus of claim 0 wherein said cable is an RF cable and said EM power source is an RF power source configured to supply EM signal at a frequency in a range between lOOKHz and 100MHz.

14. The apparatus of claim 0 wherein said EM signal is modulated by pulses. The apparatus of claim 0 wherein said EM signal is modulated by a repetitive pattern comprising an ignition pulse followed by a work pulse wherein said ignition pulse has a pulse width PW1 and an amplitude Al and said work pulse has a pulse width PW2>PW1 and an amplitude A2<A1.

The apparatus of claim 0 wherein said plasma generating EM field is between about lOOV/mm and about lOOOV/mm.

The apparatus of claim 0 wherein a voltage supplied to said electrode for applying said plasma generating EM field is between about 500V and about 5KV.

The apparatus of claim 0 wherein said power source comprises a load monitor configured for monitoring a characteristic of said EM signal delivered to said electrode, said power source being thereby configured to regulate a voltage or a current or a total power supplied to said electrode.

The apparatus of claim 0 further comprising a gas reservoir functionally associated with said gas pipe.

The apparatus of claim 0 further comprising a suction pump functionally associated with said suction pipe.

A method for providing oral treatment in a treatment site on a surface portion of a mouth of a patient, comprising:

providing the apparatus of claim 11 ;

advancing the plasma applicator to the treatment site so that at least one electrode of the plasma applicator is proximal to the surface portion of the mouth, and

supplying EM power from the power source to the electrode,

thereby exciting plasma in a region adjoining the electrode and adjoining the surface portion of the mouth of the patient.

The method of claim 21 further comprising releasing gas from the gas discharge aperture in the region of plasma excitation.

The method of claim 22 wherein said oral treatment comprises teeth bleaching, and the surface portion of the body comprises a tooth.