Devices and methods for treating skin tissue using cold plasma

Abstract

Disclosed herein is a system for treating skin and/or nails with cold plasma. The system includes a discharge device, which includes a handle and an applicator mounted thereon, and control infrastructure, which includes a waveform generator. The applicator includes an elongated tube housing therein a cathode. The handle includes a flyback amplifier. The waveform generator is configured to induce the flyback amplifier to establish a voltage at the cathode. The voltage produced by the flyback amplifier is configured to generate a self-sustaining Townsend avalanche when a distal end of the tube is positioned sufficiently near a target site on a skin surface or a nail of a subject, such that a cold plasma discharge is produced and directed at the target site and having an average power between about 0.1 µW and about 10 µW, so that the target site is not heated.

1 . A system for treating skin and nails with cold plasma, the system comprising a discharge device, which comprises a handle and an applicator, and control infrastructure, which comprises a waveform generator;
 wherein the applicator comprises an elongated tube, extending from a tube proximal end to a tube distal end, and a cathode housed within the tube, the tube being mounted, via the tube proximal end, on a distal tip portion of the handle;   wherein the handle comprises a flyback amplifier functionally associated with the waveform generator and electrically associated with the cathode, the waveform generator being configured to induce the flyback amplifier to apply a voltage at the cathode; and   wherein at least a range of the voltage produced by the flyback amplifier is configured to generate a self-sustaining Townsend avalanche when the tube distal end is positioned near a target site on a skin surface or a nail of a subject, such that a cold plasma discharge is produced and directed at the target site, the cold plasma discharge having an average electrical current amplitude in the range of about 0.1 mA to about 10 mA and an average power in the range of about 0.1 µW to about 10 µW, the system being thereby configured to treat the target site without heating thereof.   
     
     
         2 . The system of  claim 1 , wherein the waveform generator and the flyback amplifier are electrically coupled, and wherein the flyback amplifier is configured to amplify a voltage signal produced by the waveform generator, such that an instantaneous magnitude of the voltage applied at the cathode is dependent on the instantaneous magnitude of the voltage signal. 
     
     
         3 . The system of  claim 1 , wherein the voltage applied at the cathode is characterized by a series of pulses having a duty cycle in the range of 1 % to 70 %, wherein each pulse has a pulse width in the range of about 10 nsec to about 200 nsec, and wherein a frequency spectrum of the pulse includes one or more frequencies in the range of about 10 kHz to about 1 GHz; and
 preferably, wherein one or more of the pulses in the series of pulses are amplitude modulated, double-modulated, or harmonically modulated, and/or wherein one or more of the pulses in the series of pulses are amplitude modulated by a monotonically decreasing function.   
     
     
         4 . The system of  claim 1 , wherein the tube is closed on the tube distal end and comprises an inert gas and/or air at a sub-atmospheric pressure of at least about 2 kPa or higher. 
     
     
         5 . The system of  claim 4 , wherein dimensions and shape of the tube distal end are adapted to a group of lesions or a group nails having common dimensions, shape, and/or texture; and
 preferably, wherein the applicator is detachably mounted on the distal tip portion of the handle.   
     
     
         6 . The system of  claim 4 , wherein the cathode comprises a transversely extending surface, which extends over at least about 25 % of a transverse cross-section of the tube, the applicator being thereby configured for dielectric-barrier discharge; or
 wherein the cathode comprises a needle extending longitudinally within the tube, and/or wherein the applicator further comprises an electrically-conducting collimator, which is mounted on the tube distal end, the discharge device being thereby configured for corona discharge or spark discharge.   
     
     
         7 . The system of  claim 1 , wherein the control infrastructure further comprises a vacuum pump fluidly coupled to the tube via an applicator gas port on the tube proximal end, thereby allowing withdrawal of gas from the tube. 
     
     
         8 . The system of  claim 1 , wherein the tube distal end is open and configured to be pressed against skin of a subject around a target site, such that the tube distal end is fluidly sealed, wherein the control infrastructure further comprises a vacuum pump fluidly coupled to the tube via an applicator gas port on the tube proximal end, thereby allowing withdrawal of gas from the tube, and wherein, optionally, the cathode comprises a needle extending longitudinally within the tube. 
     
     
         9 . The system of  claim 7 , wherein the control infrastructure further comprises a gas supply fluidly coupled to the tube via the applicator gas port, thereby allowing injection of gas into the tube. 
     
     
         10 . The system of  claim 1 , further comprising processing and control circuitry, wherein the handle further comprises a user interface configured for a user to operate the discharge device, and wherein the processing and control circuitry is functionally associated with the waveform generator, the flyback amplifier, and the user interface, and is configured to coordinate operations thereof and to allow the user, via the user interface, to set and/or adjust electrical parameters characterizing the cold plasma discharge;
 wherein the electrical parameters comprise one or more of an average power of the cold plasma discharge, an average electrical current amplitude, a frequency or frequencies of the pulses, a waveform or waveforms of the pulses, a duration or durations of the pulses, and a separation or separations between pairs of adjacent pulses.   
     
     
         11 . The system of  claim 10 , wherein the handle further comprises a camera positioned to be at a line-of-sight from the target site when the handle is properly positioned with respect to the target site, thereby allowing generation of a cold plasma discharge directed at the target site, the camera being functionally associated with the processing and control circuitry. 
     
     
         12 . A kit for treating skin tissue using cold plasma, the kit comprising the system of  claim 5 , with the applicator being detachably mounted on the applicator, and a set of applicators, each of the applicators being configured to treat a respective group of skin or nail diseases and/or disorders having common dimensions, shape, and/or texture. 
     
     
         13 . The system of  claim 1  for use in the treatment of skin and nail diseases and disorders in a target site, the treatment comprising:
 positioning the system such that the tube distal end of the applicator is at least in proximity to a target site; and 
 closing an electrical circuit through the target site by generating a cold plasma discharge; 
 wherein the cold plasma discharge has an average electrical current amplitude in the range of about 0.1 mA to about 10 mA and an average power in the range of about 0.1 µW to about 10 µW, and wherein the cold plasma discharge comprises a series of discharge pulses, so that the target site is not heated. 
     
     
         14 . The system for use of  claim 13 , wherein the series of discharge pulses is induced by applying a voltage at the cap cathode of the applicator characterized by a series of pulses having a duty cycle in the range of 1 % to 70 %, wherein each pulse has a pulse width in the range of about 10 nsec to about 200 nsec, and wherein a frequency spectrum of the pulse includes one or more frequencies in the range of about 10 kHz to about 1 GHz; and preferably, wherein one or more of the pulses in the series of pulses are amplitude modulated, double-modulated, or harmonically modulated, and/or wherein one or more of the pulses in the series of pulses are amplitude modulated by a monotonically decreasing function. 
     
     
         15 . The system for use of  claim 13 , wherein the treatment further comprises:
 prior to the closing of the electrical circuit, determining treatment parameters, the treatment parameters at least comprising one or more parameters of the cold plasma discharge; and   subsequently to the closing of the electrical circuit, monitoring one or more plasma parameters, and adjusting one or more of the treatment parameters, contingent on at least one of the one or more monitored plasma parameters being outside a respective range.   
     
     
         16 . The kit of  claim 12 , for use in the treatment of skin and nail diseases and disorders in a target site, the treatment comprising:
 positioning the system such that the tube distal end of the applicator is at least in proximity to a target site; and   closing an electrical circuit through the target site by generating a cold plasma discharge; 
 wherein the cold plasma discharge has an average electrical current amplitude in the range of about 0.1 mA to about 10 mA and an average power in the range of about 0.1 µW to about 10 µW, and wherein the cold plasma discharge comprises a series of discharge pulses, so that the target site is not heated.