plasmas are generated using electrical energy that is delivered as either direct current ( dc ) electricity or alternating current ( ac ) electricity at frequencies from about 0 . 1 hertz ( hz ) to about 100 gigahertz ( ghz ), including radio frequency (“ rf ”, from about 0 . 1 mhz to about 100 mhz ) and microwave (“ mw ”, from about 0 . 1 ghz to about 100 ghz ) bands , using appropriate generators , electrodes , and antennas . choice of excitation frequency , the workpiece , as well as the electrical circuit that is used to deliver electrical energy to the circuit affects many properties and requirements of the plasma . the performance of the plasma chemical generation , the delivery system and the design of the electrical excitation circuitry are interrelated as the choices of operating voltage , frequency and current levels ( as well as phase ) effect the electron temperature and electron density . further , choices of electrical excitation and plasma device hardware also determine how a given plasma system responds dynamically to the introduction of new ingredients to the host plasma gas or liquid media . the corresponding dynamic adjustment of the electrical drive , such as via dynamic match networks or adjustments to voltage , current , or excitation frequency may be used to maintain controlled power transfer from the electrical circuit to the plasma . referring initially to fig1 , a plasma system 10 is disclosed . the system 10 includes a plasma device 12 that is coupled to a power source 14 , an ionizable media source 16 and a precursor source 18 . power source 14 includes any suitable components for delivering power or matching impedance to plasma device 12 . more particularly , the power source 14 may be any radio frequency generator or other suitable power source capable of producing power to ignite the ionizable media to generate plasma . the plasma device 12 may be utilized as an electrosurgical pencil for application of plasma to tissue and the power source 14 may be an electrosurgical generator that is adapted to supply the device 12 with electrical power at a frequency from about 0 . 1 mhz to about 2 , 450 mhz and in another embodiment from about 1 mhz to about 160 mhz . the plasma may also be ignited by using continuous or pulsed direct current ( dc ) electrical energy . the precursor source 18 may be a bubbler or a nebulizer configured to aerosolize precursor feedstocks prior to introduction thereof into the device 12 . the precursor source 18 may also be a micro droplet or injector system capable of generating predetermined refined droplet volume of the precursor feedstock from about 1 femtoliter to about 1 nanoliter in volume . the precursor source 18 may also include a microfluidic device , a piezoelectric pump , or an ultrasonic vaporizer . the system 10 provides a flow of plasma through the device 12 to a workpiece “ w ” ( e . g ., tissue ). plasma feedstocks , which include ionizable media and precursor feedstocks , are supplied by the ionizable media source 16 and the precursor source 18 , respectively , to the plasma device 12 . during operation , the precursor feedstock and the ionizable media are provided to the plasma device 12 where the plasma feedstocks are ignited to form plasma effluent containing ions , radicals , photons from the specific excited species and metastables that carry internal energy to drive desired chemical reactions in the workpiece “ w ” ( e . g ., tissue ) or at the surface thereof . the feedstocks may be mixed upstream from the ignition point or midstream thereof ( e . g ., at the ignition point ) of the plasma effluent , as shown in fig1 and described in more detail below . the ionizable media source 16 provides ionizable feedstock to the plasma device 12 . the ionizable media source 16 is coupled to the plasma device 12 and may include a storage tank and a pump ( not explicitly shown ). the ionizable media may be a liquid or a gas such as argon , helium , neon , krypton , xenon , radon , carbon dioxide , nitrogen , hydrogen , oxygen , etc . and their mixtures , and the like , or a liquid . these and other gases may be initially in a liquid form that is gasified during application . the precursor source 18 provides precursor feedstock to the plasma device 12 . the precursor feedstock may be either in solid , gaseous or liquid form and may be mixed with the ionizable media in any state , such as solid , liquid ( e . g ., particulates or droplets ), gas , and the combination thereof . the precursor source 18 may include a heater , such that if the precursor feedstock is liquid , it may be heated into gaseous state prior to mixing with the ionizable media . in one embodiment , the precursors may be any chemical species capable of forming reactive species such as ions , electrons , excited - state ( e . g ., metastable ) species , molecular fragments ( e . g ., radicals ) and the like , when ignited by electrical energy from the power source 14 or when undergoing collisions with particles ( electrons , photons , or other energy - bearing species of limited and selective chemical reactivity ) formed from ionizable media 16 . more specifically , the precursors may include various reactive functional groups , such as acyl halide , alcohol , aldehyde , alkane , alkene , amide , amine , butyl , carhoxlic , cyanate , isocyanate , ester , ether , ethyl , halide , haloalkane , hydroxyl , ketone , methyl , nitrate , nitro , nitrile , nitrite , nitroso , peroxide , hydroperoxide , oxygen , hydrogen , nitrogen , and combination thereof . in embodiments , the chemical precursors may be water , halogenoalkanes , such as dichloromethane , tricholoromethane , carbon tetrachloride , difluoromethane , trifluoromethane , carbon tetrafluoride , and the like ; peroxides , such as hydrogen peroxide , acetone peroxide , benzoyl peroxide , and the like ; alcohols , such as methanol , ethanol , isopropanol , ethylene glycol , propylene glycol , alkalises such as naoh , koh , amines , alkyls , alkenes , and the like . such chemical precursors may be applied in substantially pure , mixed , or soluble form . the precursors and their functional groups may be delivered to a surface to react with the surface species ( e . g ., molecules ) of the workpiece “ w .” in other words , the functional groups may be used to modify or replace existing surface terminations of the workpiece “ w ” or materials disposed thereon . the functional groups react readily with the surface species due to their high reactivity and the reactivity imparted thereto by the plasma . in addition , the functional groups are also reacted within the plasma volume prior to delivering the plasma volume to the workpiece . some functional groups generated in the plasma can be reacted in situ to synthesize materials that subsequently form a deposition upon the surface . this deposition may be used for stimulating healing , killing bacteria , and increasing hydrophilic or hydroscopic properties . in addition , deposition of certain function groups may also allow for encapsulation of the surface to achieve predetermined gas / liquid diffusion , e . g ., allowing gas permeation but preventing liquid exchange , to bond or stimulate bonding of surfaces , or as a physically protective layer . with reference to fig1 and 2 , the precursor source 18 and the ionizable media source 16 may be coupled to the plasma device 12 via tubing 114 and 113 , respectively . the tubing 114 and 113 may be combined into unified tubing to deliver a mixture of the ionizable media and the precursor feedstock to the device 12 at a proximal end thereof . this allows for the plasma feedstocks , e . g ., the precursor feedstock and the ionizable gas , to be delivered to the plasma device 12 simultaneously prior to ignition of the mixture therein . in another embodiment , the ionizable media source 16 and the precursors source 18 may be coupled to the plasma device 12 via the tubing 114 and 113 at separate connections , such that the mixing of the feedstocks occurs within the plasma device 12 upstream from the ignition point . in other words , the plasma feedstocks are mixed proximally of the ignition point , which may be any point between the respective sources 16 and 18 and the plasma device 12 , prior to ignition of the plasma feedstocks to create the desired mix of the plasma effluent species for each specific surface treatment on the workpiece “ w .” in a further embodiment , the plasma feedstocks may be mixed midstream , e . g ., at the ignition point or downstream of the plasma effluent , directly into the plasma . it is also envisioned that the ionizable media may be supplied to the device 12 proximally of the ignition point , while the precursor feedstocks are mixed therewith at the ignition point . in a further illustrative embodiment , the ionizable media may be ignited in an unmixed state and the precursors may be mixed directly into the ignited plasma . prior to mixing , the plasma feedstocks may be ignited individually . the plasma feedstock is supplied at a predetermined pressure to create a flow of the medium through the device 12 , which aids in the reaction of the plasma feedstocks and produces a plasma effluent . the plasma according to the present disclosure is generated at or near atmospheric pressure under normal atmospheric conditions . the system 10 further includes a suction source 15 ( e . g ., negative pressure source ) configured to siphon tissue and unreacted components from the treatment site . the suction source 15 may be a vacuum pump , fan , circulator , and the like and is coupled to the device 12 . with reference to fig2 and 3 , the device 12 is shown as a plasma applicator 100 . the applicator 100 includes a handle 101 and a longitudinal shaft 102 coupled thereto . the shaft 102 includes a proximal portion 104 coupled to the handle 101 and a distal portion 106 . the catheter shaft 102 includes a plasma lumen 103 defined therein and extending the entire length thereof and terminating in an opening 105 at distal end of the distal portion 106 . the shaft 102 may have a diameter from about 5 mm to about 10 mm allowing the applicator 100 to be inserted through operating ports for application of the plasma effluent 32 at the operating site during laparascopic procedures or through natural body orifices . in another embodiment , the applicator 100 may be configured for use within or accompanied by a flexible endoscope . the catheter shaft 102 may slidably disposed within the handle 101 allowing for the longitudinal movement of the catheter shaft 102 ( e . g ., extension and retraction ). the catheter shaft 102 may include a stop or a shoulder at a proximal end thereof that abuts a complementary shoulder or stop disposed within the handle 101 to prevent further extension of the catheter shaft 102 . the device 12 also includes controls 111 ( e . g ., toggle switch , trigger , etc .) coupled to the power source 14 and the ionizable media source 16 . upon actuation , the controls 111 regulate the flow of ionizable media from the ionizable media source 16 and the precursors source 18 as well as the flow of power from the power source 14 , such that the ionizable media flowing through the lumen 103 is ignited therein and is ejected from the opening 105 to form the plasma effluent 32 . the handle 101 includes a rotating assembly 123 for controlling the rotational movement of the distal portion 106 about a longitudinal axis of the catheter shaft 112 . the rotating assembly 123 engages one or more gears ( not shown ) which are attached to the catheter shaft 112 . in one embodiment , the ratio of rotation of rotating assembly 123 to distal portion 106 is 1 : 1 , however , it is contemplated that a different gearing structure may be incorporated to increase or decrease the rotational ratio depending upon a particular purpose . in one embodiment , the distal portion 106 is configured for controlled deflection . a pull - wire 107 ( fig3 ) or another suitable actuation mechanism extends from the handle 101 at the proximal end of the catheter 100 through a lumen in the catheter shaft 102 and is fastened to the distal portion 106 . the pull - wire 107 is movable from a first generally relaxed position wherein the distal portion 106 is disposed in a generally longitudinally - aligned position relative to the proximal portion 104 to a second retracted or tensed position wherein the distal portion 106 flexes ( e . g ., deflects ) from the proximal portion 104 at a desired angle as shown in fig2 . the distal portion 106 is constructed to be more flexible than the proximal portion 104 , such that when the handle 101 is pulled back or otherwise actuated , the pull - wire bends the distal portion 106 from an undeflected position to a deflected position . in particular , the proximal portion 104 may include a wire or other support materials ( not shown ) therein to provide tensile strength to the catheter shaft 102 while still maintaining flexibility for maneuvering through a vascular system . the distal portion 106 is formed from a flexible biocompatible material such as polytetrafluoroethylene , polyurethane , polyimide , and the like to allow for maneuverability thereof . the applicator 100 includes two or more electrodes 108 and 110 disposed at the distal portion 106 . the electrodes 108 and 110 may be formed from a conductive material and have a ring - like shape . the electrodes 108 and 110 may be disposed over the distal portion 106 to provide for capacitive coupling with the ionizable media . in another embodiment , the electrodes 108 and 110 may be formed as needle electrodes ( e . g ., pointed tip ) and may be disposed within the distal portion 106 . the electrodes 108 and 110 are coupled to conductors ( not shown ) that extend through the catheter shaft 102 and are connected to the power source 14 via electrical connectors 112 . the catheter shaft 102 is also coupled to the ionizable media source 16 via gas tubing 114 and to the precursors source 16 via tubing 113 . the ionizable media source 16 and the precursors source 16 may include various flow sensors and controllers ( e . g ., valves , mass flow controllers , etc .) to control the flow of ionizable media to the applicator 100 . in particular , the lumen 103 is in gaseous and / or liquid communication with the ionizable media source 16 and the precursors source 18 allowing for the flow of ionizable media and precursor feedstocks to flow through the catheter shaft 102 to the distal portion 106 . the ionizable media in conjunction with the precursor feedstocks is ignited by application of energy through the electrodes 108 and 110 to form plasma effluent 32 exiting through the opening 105 . the applicator 100 also includes a suction lumen 150 coupled to the negative pressure source 19 . this allows for the removal of unreacted feedstocks and debris particles to be removed from the application site . the lumen 150 may be incorporated into the shaft 102 ( fig3 ) or may be a separate tube 152 coupled in parallel to the shaft 102 ( fig2 ). the tube 152 may include a distal portion 128 that extends distally past the distal portion 106 . the lumen 150 may be coupled to a suction source 15 via tubing 115 . the applicator 100 may also include a temperature sensor 130 at the distal portion 106 . the temperature sensor 130 may be a thermistor , a thermocouple , or any other type of suitable temperature sensor that is coupled to the power source 14 . the temperature sensor 130 provides continual temperature readings to the power source 14 , which then adjusts the energy supplied to the plasma feedstocks to regulate the energy output of the plasma effluent 32 . the applicator 100 is suitable for removing biofilms from various type of medical implants , namely , lumens of various implants ( e . g ., endotracheal tubes ). tracheal tubes provide a source for bacterial growth within lumens where environment is warm and moist providing ideal conditions for bacterial growth . since the lumens are inaccessible by the immune system the bacterial growth advances into biofilms that cannot be eliminated by conventional chemical treatments . growth of the biofilms inside the tracheal tubes leads to costly tube replacement procedures . the applicator 100 generates the plasma effluent 32 that removes the biofilm and deactivates bacterial contamination within the endotracheal tube . fig4 shows an exemplary embodiment of an endotracheal tube 311 implanted in a trachea 319 . the endotracheal tube 311 includes tubing 313 having a distal end portion 302 adapted to be orally inserted in a patient &# 39 ; s trachea 319 and a proximal end portion 304 adapted to protrude from the patient &# 39 ; s mouth . the tubing 313 defines a lumen 317 therethrough and is sufficiently flexible to bend and conform to the patient &# 39 ; s anatomy , but has sufficient structural integrity to prevent kinking and collapsing during insertion . the lumen 317 terminates in an opening 303 at the distal end portion 302 . the tubing 313 may be formed from a medical grade silicone plastic material that is stable at a temperature range from about 0 ° c . to about 60 ° c . tube 313 may be formed from a single piece of silicone plastic of extruded construction . as illustrated in fig4 , the tubing 313 is flexible and conforms to the patient &# 39 ; s anatomy when inserted . the tubing 313 is resistant to collapse while being intubated or after being in place for great lengths of time . the distal portion 302 of the endotracheal tube 311 is provided with an expandable cuff or balloon 331 of a gas impervious material such as a thin sheet of silicone material of the type described above . cuff 331 may be inflated by a pilot balloon or a syringe ( not shown ) in gaseous communication therewith ( e . g ., connected to the cuff 331 by an external tube and internal passage in the wall of tube 13 ). when the cuff 331 is inflated to engage the wall of trachea 319 , air or other gases pass to and from a patient &# 39 ; s lungs , 327 , 329 , through the bronchi 323 , 325 and through the lumen 317 of the tube 311 . the proximal end 304 of the tube 311 is adapted to be connected to a ventilator or oxygen source and / or a suction device . with reference to fig5 and 6 , a biofilm removal method using the applicator 100 is discussed . fig5 illustrates the endotracheal tube 311 and fig6 illustrates a flow chart of a method for removing the biofilm therefrom . in step 400 , the opening 303 is selectively blocked using a seal 306 , which may be temporarily adhered within the lumen 317 . the seal 306 may be delivered to the distal end portion 302 using a variety of endoscopic instruments and techniques that provide for visual access to anatomical lumens . the seal 306 blocks the opening 303 to prevent bacteria released from the surface by the plasma effluent 32 to be introduced into the patient &# 39 ; s lungs 327 and 329 . seal 306 may have a profile configured to match the opening 303 thereby sealing the opening 303 . the seal 306 may be disposed within the lumen 306 . in embodiments , the seal 306 may abut against an interior lip of the opening 303 such that the seal 306 does not pass beyond opening 303 . seal 306 may be secured to the lumen 317 via a living hinge or any other pivotable attachment that enables the seal 306 to move within the lumen 317 with minimum contact . the seal 306 may be made of polypropylene or any other suitable polymer from which the living hinge element may be formed . forward movement / pressure by the applicator 100 holds seal 306 against the opening lip of 303 . when plasma is deactivated , the applicator 100 may be withdrawn from the lumen 306 and / or away from the seal 306 to enable air to pass therethrough thereby allowing for intermittent respiration for the patient . in embodiments , the applicator 100 may include a contact sensor ( e . g ., pressure actuated limit switch ) at the distal portion 106 , which is coupled to the controls 111 . the contact sensor acts as a safety lockout preventing plasma activation via the controls 111 when the contact sensor is disengaged from the seal 306 . this ensures that the seal 306 is closed prior to activation and subsequent application of the plasma plume . in step 402 , the applicator 100 is inserted into the lumen 317 . the distal portion 106 may be deflected to direct the plasma effluent 32 toward the biofilm . in one embodiment , the deflection may be from about 0 ° to about 45 ° with respect to a longitudinal axis defined by the shaft 102 . in step 404 , the ionizable media along with precursors is supplied to the applicator 100 and is ignited therein to form the plasma effluent 32 . in one embodiment , the ionizable media may be argon , helium or a mixture thereof and the precursors may be hydrogen peroxide , water , oxygen , nitrogen or mixtures thereof . in step 406 , the applicator 100 is moved across the lumen 317 ensuring that the plasma effluent 32 is directed at walls thereof to remove the biofilm . as biofilm is removed , bacteria and other debris is removed from the treatment site through the suction lumen 150 via suction source 15 . the temperature of the plasma effluent 32 is from about 60 °, allowing the plasma to be used within the silicone tube 311 without damaging the walls thereof . the relatively low temperature of the plasma effluent 32 does not affect its ability to remove biofilm , since the primary effect on bacteria is due to the chemical reactivity of the plasma constituents ( e . g ., ionized plasma feedstocks ). the precursors supplied to the applicator 100 are specifically chosen to generate a selectively reactive plasma effluent 32 . in other words , the precursors , when ignited , produce a plasma effluent 32 that interacts with bacteria , and has little to no effect on material of the tube 311 . the emissions may be measured in the plasma effluent 32 by an optical spectrometer ( not shown ) including an optical fiber positioned to capture the emission from the plasma effluent 32 at the area of contact with the lumen 317 . in embodiments , nuclear magnetic resonance ( nmr ) and / or laser induced florescence ( lif ) devices may be used to evaluate the gas evacuated from the tube 128 at the location of suction source 15 . in further embodiments , a second plasma ignition point in the effluent from tube 128 may be ignited enabling the emissions to be monitored in the plasma effluent 32 directly at the optical spectrometer at suction source 15 . in step 408 , the effect of the plasma treatment is monitored by measuring the spectra of the application of the plasma effluent 32 . the spectra are observed for specific emissions related to the destruction of the biofilms . the spectra are used to confirm the destruction of the biofilm and are used as a feedback mechanism for advancing of the applicator 100 . in particular , the spectra are used by the user to determine when a specific region of the lumen 317 is substantially cleared of the biofilm allowing the user to determine when the applicator 100 may be advanced further into the lumen 317 and additional biofilm may be removed . the distal portion 106 may also be advanced by extending the catheter shaft 102 in a distal direction . additionally , the spectra may be used to determine when the lumen 317 is substantially clear of the biofilm and application of the plasma effluent 32 may be terminated . in step 410 , the applicator 100 is extracted from the lumen 317 and the seal 306 is removed , restoring the functionality of the tube 311 . although the illustrative embodiments of the present disclosure have been described herein with reference to the accompanying drawings , it is to be understood that the disclosure is not limited to those precise embodiments , and that various other changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the disclosure . in particular , as discussed above this allows the tailoring of the relative populations of plasma species to meet needs for the specific process desired on the workpiece surface or in the volume of the reactive plasma .
a method for removing biofilm from a lumen of a medical implant is disclosed . the method includes the steps of inserting a plasma applicator into a lumen defined in a medical implant , the lumen having a proximal end portion and a distal end portion having an opening therein , positioning the plasma applicator adjacent a biofilm formation , generating a selectively reactive plasma effluent at the plasma applicator and directing the selectively reactive plasma effluent at the biofilm formation .