Patent Publication Number: US-2010125267-A1

Title: Plasma Gun for Bio/Medical Treatment

Description:
CROSS-REFERENCE 
     This application claims priority to Korean Application No. 10-2008-0113272, filed Nov. 14, 2008, which is hereby incorporated by reference in its entirety 
     TECHNICAL FIELD 
     The present invention relates to a bio/medical apparatus, more particularly, to a plasma gun for medical treatment using atmospheric plasma, and still more particularly, to a plasma gun for medical treatment having the configuration suitable for medical applications such as healing for injuries, sterilization for biological tissues, treatment for blood coagulation, healing for skin tumors, healing for bone tumors, fat management and treatment, and skin management and operation 
     BACKGROUND 
     Plasma having electrons, ion species, and neutral active species with high energy has been employed in various applications for a long time due to an effective surface treatment mechanism. As the large-sized flat panel display industry is grown, there is a need for apparatuses that process a workpiece in line under atmospheric pressure instead of using plasma conventionally generated under a vacuum condition, and a technique using atmospheric plasma substitutes conventional vacuum equipments with the apparatuses operating under atmospheric pressure, whereby the technique using atmospheric plasma is gradually employed in various applications. 
     Even in bio/medical fields, there have been many efforts to utilize plasma capable of various surface treatment depending on types of reaction gases, power source properties and the like, and attempts have recently been realized to apply the plasma more safely and effectively. 
     For example, U.S. Patent Application Publication No. US2007/0029500 filed and published with the title of “Plasma Source and Applications thereof” discloses an apparatus, which comprises a plasma forming region, a plasma excitation region and a plasma exit and can be used in the limited treatment applications such as healing for skin and removal of damaged skins. The disclosed apparatus is configured so that an activated electrode having a capillary structure passes into a tube, which is provided with an exit and serves as a ground electrode, and a reaction gas is supplied into the tube. 
     Since the aforementioned conventional apparatus has a problem in that there is no sufficient allowance for time during which the reaction gas is ignited, it has been difficult to allow the plasma to be stably and reliably generated. Further, since a gap between the activated electrode and the ground electrode is fixed, there is a problem in that the degree of freedom in design is deteriorated. Furthermore, since the thin and elongate tube having the exit serves as a nozzle, the conventional apparatus has no option but to allow the plasma to exit in the form of a point having a small fixed area, which makes it impossible to vary the operational area of the plasma and to realize various medical applications. Still furthermore, since the power source in the conventional apparatus is limited to a radio frequency (RF) power source, there is a problem in that a type of the reaction gas which may be used in the conventional apparatus is limited. 
     SUMMARY 
     Accordingly, an object of the present invention is to provide a plasma gun for medical treatment, wherein an improved configuration of a chamber supplied with a reaction gas and a plasma discharge unit independently positioned within the chamber causes the plasma to be stably and reliably generated, so that the generated plasma may be used as medial applications for biological tissues, and wherein various nozzles capable of adjusting the area (and shape) of the plasma may be employed. 
     According to an aspect of the present invention, there is provided a plasma gun for medical treatment using atmospheric plasma, which comprises a housing having an elongate chamber provided therein, the chamber having an end at which a nozzle for spraying plasma is positioned; a gas supply unit for supplying a reaction gas to the chamber; and a plasma discharge unit formed with an elongate cavity communicating with the nozzle, the plasma discharge unit including first and second electrodes and a dielectric or insulating barrier material for plasma ignition in the elongate cavity. 
     According to an embodiment of the present invention, the dielectric may be a tubular dielectric defining the elongate cavity therein, and the first and second electrodes may be arranged on an outer surface of the tubular dielectric to be spaced apart from each other. 
     According to another embodiment of the present invention, the dielectric may be a tubular or bulk dielectric defining the elongate cavity therein, and the first and second electrodes may be formed by printing a metallic material on an outer surface of the dielectric. 
     According to a further embodiment of the present invention, the first and second electrodes may be shaped to define the elongate cavity when the first and second electrodes mate with each other with an insulating material or dielectric material interposed therebetween. 
     According to a still further embodiment of the present invention, the first electrode may be a metallic tube defining the elongate cavity, the second electrode may be a metallic rod positioned within the elongate cavity to be spaced apart from the first electrode, and the dielectric is coated or installed to an inner surface of the first electrode or an outer surface of the second electrode. 
     Preferably, a power source connected to the first electrode or the second electrode may be a medium frequency (MF) power source. 
     Preferably, the nozzle may be configured to be detached and remounted, i.e., to be replaceable. 
     The plasma gun according to an embodiment of the present invention may be configured so that a pulse power source or a sinusoidal wave type power source of low peak current is used or on-off timing of a power source is adjusted to control plasma discharge temperature. 
     According to another aspect of the present invention, there is provided a plasma gun for medical treatment, wherein electrodes for generating plasma are included in an elongate cavity communicating with a nozzle, a dielectric is positioned adjacent to at least one of the electrodes, and a medium frequency (MF) power source is used as a power source for supplying high voltage power to at least one of the electrodes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view illustrating a plasma gun for medical treatment according to an embodiment of the present invention. 
         FIG. 2  is a sectional view of the plasma gun for medical treatment shown in  FIG. 1 , illustrating a plasma discharge unit according to the embodiment of the present invention. 
         FIG. 3  is a view illustrating a plasma discharge unit of a plasma gun for medical treatment according to another embodiment of the present invention. 
         FIG. 4  is a view illustrating a plasma discharge unit of a plasma gun for medical treatment according to a further embodiment of the present invention. 
         FIGS. 5   a,    5   b  and  5   c  are views illustrating plasma discharge units of plasma guns for medical treatment according to still further embodiments of the present invention. 
         FIGS. 6(   a ) and ( b ) are views illustrating replaceable nozzles of plasma guns for medical treatment according to still further embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided only for illustrative purposes so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the following embodiments but may be implemented in other forms. In the drawings, the widths, lengths, thicknesses and the like of elements may be exaggerated for convenience of illustration. Like reference numerals indicate like elements throughout the specification and drawings. 
       FIG. 1  is a view illustrating a plasma gun for medical treatment according to an embodiment of the present invention. 
     Referring to  FIG. 1 , a plasma gun  1  for medical treatment of this embodiment includes an elongate housing  10  having a knob  11  attached to a lower portion thereof. The elongate housing  10  has an elongate chamber  102  defined therein, and a nozzle for spraying plasma generated as described below is positioned at an end of the chamber  102 . 
     In addition, the plasma gun  1  for medical treatment further includes a plasma discharge unit  20 , which has electrodes and a dielectric or insulating barrier material and provided in the elongate chamber  102 . The plasma discharge unit  20  is to generate stable and reliable atmospheric plasma using dielectric barrier discharge (i.e., DBD) under the atmospheric pressure condition, and may be maintained to be fixed in the elongate chamber  102  by any holder (not shown) arranged in the elongate chamber  102 . 
     Also, the plasma gun  1  for medical treatment further includes a gas supply unit  30  for supplying a reaction gas into the elongate chamber  102  and a power source  40  for applying high voltage to at least one of the electrodes of the plasma discharge unit  20 . The gas supply unit  30  allows the reaction gas to flow in the elongate chamber  102  at large pressure enough to provide spraying force to the plasma generated as described below. 
     According to a preferred embodiment of the present invention, the power source  40  supplies the electrodes of the plasma discharge unit  20  with medium frequency (MF) power whose the frequency ranges from some tens of kHz to some hundreds of kHz. In connection with the foregoing, the gas supply unit  30  may supply the elongate chamber  102  with various kinds of reaction gases (or process gases) such as O 2  and CO 2  as well as He. 
     Meanwhile, the knob  11  is provided with a switch  112  with which a user may selectively turns on/off the power source  40  for supplying the plasma discharge unit  20  with high voltage power. The plasma gun for medical treatment may have a handheld configuration having a knob, as shown in  FIG. 1 , or the configuration which may be mounted to a robot arm although not shown. 
     In the meantime, the plasma gun  1  for medical treatment may adjust the plasma temperature in a broader range by using a pulse power source or a sinusoidal wave type power source of low peak current and/or a regulator for adjusting on/off timing of the high voltage power. Such adjustment of the plasma temperature allows the plasma gun  1  for medical treatment to be broadly applied for various medical applications for various biological tissues. 
       FIG. 2  is a sectional view illustrating in more detail the configuration of the plasma discharge unit provided within the plasma gun shown in  FIG. 1 . 
     Referring to  FIG. 2 , the plasma discharge unit  20  includes a hollow cylindrical dielectric  21  having an elongate cavity  212  provided therein, and first and second electrodes  22   a  and  22   b  made of metal which are arranged to face each other and to be spaced apart from each other on an outer surface of the dielectric  21 . 
     The first and second electrodes  22   a  and  22   b  of metallic plates are installed to face each other and to be spaced apart from each other on the outer surface of the hollow cylindrical dielectric  21 . At this time, the first electrode  22   a  is connected to the MF power source  40 , thereby being supplied with the high voltage power from the MF power source  40 , while the second electrode  22   b  serves as a ground electrode. Alternatively, instead of using one of the electrodes as the ground electrode, the first and second electrodes  22   a  and  22   b  may serve as relative electrodes which respectively have positive and negative polarities. The hollow cylindrical dielectric  21  may be formed of an insulating material such as ceramic or polymer. 
     If the high voltage power from the MF power source  40  is applied to the first electrode  22   a  and/or the second electrode  22   b , the dielectric barrier discharge causes the reaction gas to be stably plasma-ignited in the elongate cavity  212  in the dielectric, and the generated plasma is sprayed to the outside through an end of the elongate cavity  212 , i.e., a plasma ejection hole. At this time, the shape and area of the plasma to be sprayed may be adjusted depending on the shape of a spraying nozzle adjacent to the ejection hole. 
       FIG. 3  is a sectional view illustrating the configuration of a plasma discharge unit according to another embodiment of the present invention. 
     Referring to  FIG. 3 , the plasma discharge unit  20  according to this embodiment includes a bulk dielectric  22  having an elongate cavity  222  bored through the central region thereof. Further, the bulk dielectric  22  has a cross section of a substantially quadrangular shape, and includes first and second patterned electrodes  23   a  and  23   b  which are formed by printing a conductive metal material on both opposite surfaces. As in the previous embodiment, if the high voltage from an MF power source is applied to the first and second patterned electrode  23   a  and  23   b,  the dielectric barrier discharge allows stable and reliable plasma to be generated in the elongate cavity  222  through which the reaction gas flows. Further, the generated plasma is sprayed to the outside through a plasma ejection hole positioned at an end of the elongate cavity  222  and a nozzle continued to the plasma ejection hole. At this time, the bulk dielectric  22  is preferably made of ceramic or polymer. The dielectric having a cross section of a rectangular shape is shown in the figure but there is no limitation concerning the sectional shape of the bulk dielectric  22  if an elongate cavity is formed therein. 
       FIG. 4  is a sectional view illustrating the configuration of a plasma discharge unit according to a further embodiment of the present invention. 
     Referring to  FIG. 4 , the plasma discharge unit  20  according to this embodiment includes a tubular member  24  which is made of an elongate metal and has an elongate cavity  242  formed therethrough. Further, the tubular member  24  includes first and second channel-shaped electrodes  24   a  and  24   b  which mate with each other to define the elongate cavity  242 . The first and second channel-shaped electrodes  24   a  and  24   b  are insulated from each other by a dielectric material or insulating material  25  interposed therebetween. At this time, the insulating material  25  may be an adhesive for providing adhesion to a portion where the first and second channel-shaped electrodes  24   a  and  24   b  mate with each other. Further, a dielectric  26  for dielectric barrier discharge is partially or entirely formed on an inner surface of the tubular member  24 . 
       FIGS. 5   a  to  5   c  are sectional views illustrating the configuration of plasma discharge units according to still further embodiments of the present invention. 
     In the plasma discharge units shown in  FIGS. 5   a  to  5   c,  a first electrode  26   a  is made of a metallic tube for defining an elongate cavity  262 , and a second electrode  26   b  is made of a metallic rod positioned in the elongate cavity  262  to be spaced apart from the first electrode  26   a.  A dielectric  27  may be formed on an inner surface of the first electrode  26   a  (as shown  FIG. 5   a ), an outer surface of the second electrode  26   b  (as shown in  FIG. 5   b ), or both of the inner surface of the first electrode  26   a  and the outer surface of the second electrode  26   b  (as shown in  FIG. 5   c ). At this time, the dielectric is formed on the first electrode  26   a  and/or the second electrode  26   b  by a coating or attaching process. 
       FIGS. 6(   a ) and ( b ) are sectional views illustrating the configuration of nozzles of plasma guns for medical treatment according to embodiments of the present invention. 
     Referring to  FIGS. 6(   a ) and ( b ), a nozzle  29   a  or  29   b  is configured to be replaceably detached and remounted and to communicate with an end of an elongate cavity  282 , i.e., a plasma ejection hole, formed on the plasma discharge unit  20  which includes the electrodes and the dielectric. For the purpose of the detachment and remounting, the nozzle  29   a  or  29   b  is coupled adjacent to the ejection hole of the plasma gun, for example, in a screwing or hooking manner.  FIG. 6(   a ) shows the configuration of the nozzle  29   a  for spraying plasma to be converged to a minute dimension, while  FIG. 6(   b ) shows the configuration of the nozzle  29   b  for spraying the plasma to be broadly diffused. Instead of the function or shape of the nozzles as shown in  FIGS. 6(   a ) and ( b ), nozzles with various functions and shapes may be replaceably used. 
     The present invention may be broadly used in various medical applications, as compared with conventional applications, for example, healing for injuries, sterilization for biological tissues, treatment for blood coagulation, healing for skin tumors, healing for bone tumors, fat management and treatment, and skin management and operation. The plasma gun for medical treatment according to the present invention has advantages in that the improved configuration of the chamber for supplying the reaction gas and the plasma discharge unit independently positioned within the chamber causes the plasma to be stably and reliably generated, so that the generated plasma can be preferably used as medial applications for biological tissues, and the application range of the plasma gun for medical treatment can be increased by employing various nozzles capable of adjusting the area (and shape) of the plasma. Further, the present invention has an advantage in that the application range of the plasma gun for medical treatment can be increased by adjusting the temperature of the plasma. Furthermore, the efficiency of the plasma gun can be more improved by employing the configuration in which the flow of the reaction gas is changed into a tangential flow or a laminar flow.