Patent Publication Number: US-2017360974-A1

Title: Plasmaclave Device

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/352,971 filed on Jun. 21, 2016 and entitled “Plasmaclave Device,” which is hereby incorporated by reference for all purposes. 
    
    
     BACKGROUND 
     Reusable medical equipment must be sterilized after each use and before the next use. A common sterilization technique includes autoclaving the medical equipment. In this technique, the medical equipment is placed inside an autoclave device (much like an oven) and heated at a sufficiently high temperature for a sufficiently long period of time to ensure that any pathogens on the medical equipment is killed, destroyed or eliminated. The high temperatures required for such techniques require that the equipment cool down after the process is complete, which adds time to the process. The high temperatures also present a potential hazard to whomever handles the medical equipment after the autoclaving process is completed. 
     Atmospheric pressure plasma processes for sterilizing objects are known. In these processes, a plasma torch is used to generate a plasma and project the plasma out of an orifice, typically using gas flow. The objects to be sterilized are placed beneath the projected plasma. These atmospheric pressure systems typically focus the plasma to a small spot or line, and in some cases the objects to be sterilized are moved beneath the plasma to cover a larger area. 
     SUMMARY 
     In accordance with some embodiments, a plasmaclave device used to sterilize objects includes a chamber, a stationary tray, a constrained plasma zone, one or more high voltage electrodes, fixed magnets, and steering coils. The stationary tray is disposed within the chamber. The stationary tray has a target surface and is configured to hold the objects on the target surface. The constrained plasma zone is within the chamber adjacent to the target surface of the stationary tray. The high voltage electrodes, the fixed magnets, and the steering coils are disposed within the chamber. The high voltage electrodes generate an electric field that creates a plasma within the chamber. The fixed magnets focus the electric field constraining the plasma into the constrained plasma zone of the of the chamber. The steering coils further constrain the plasma, and scan the further constrained plasma over the target surface of the stationary tray. 
     In accordance with some embodiments, a method of sterilizing objects includes providing a chamber having a stationary tray and a constrained plasma zone therein, the objects being on a target surface of the stationary tray; creating a plasma within the chamber by generating an electric field therein; pulsing the plasma at a repetition frequency using a power supply; constraining the plasma into the constrained plasma zone by focusing the electric field using fixed magnets; and further constraining the plasma and scanning the further constrained plasma across the objects on the target surface of the stationary tray using steering coils. 
     In some embodiments, the plasma is a DC plasma. In some embodiments, the plasma is an AC plasma with a frequency from 1 kHz to 1 MHz. In some embodiments, the plasma is pulsed with a repetition frequency from 1 Hz to 1 kHz. In some embodiments, a pressure in the chamber is from 1 Torr to 10 Torr. In some embodiments, a power supply is included that produces the plasma at a power level from 10 W to 100 W per 20 square inches of chamber volume. In some embodiments, the stationary tray comprises aluminum. In some embodiments, a maximum temperature of the objects or equipment being sterilized is less than or equal to 200° C. In some embodiments, the constrained plasma is scanned over the constrained plasma zone in a serpentine pattern. In some embodiments, the constrained plasma is scanned over the constrained plasma zone in a raster pattern. In some embodiments, a time period for completing a scan cycle is between 0.1 second and 1 second per cycle. In some embodiments, the objects or equipment to be sterilized are located in a portion of the constrained plasma zone, and the further constrained plasma is scanned over the portion of the constrained plasma zone containing the objects or equipment to be sterilized. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a simplified schematic diagram of an example plasmaclave device in accordance with some embodiments. 
         FIG. 1B  is a simplified schematic diagram of an example plasmaclave device in accordance with some embodiments. 
         FIG. 2  is a simplified block diagram of the example plasmaclave device shown in  FIG. 1A or 1B  in accordance with some embodiments. 
         FIG. 3  is a simplified schematic diagram of another example plasmaclave device in accordance with some embodiments. 
         FIG. 4  is a simplified block diagram of the example plasmaclave device shown in  FIG. 3  in accordance with some embodiments. 
         FIG. 5  is a simplified schematic diagram of yet another example plasmaclave device in accordance with some embodiments. 
         FIG. 6  is a simplified block diagram of the example plasmaclave device shown in  FIG. 5  in accordance with some embodiments. 
         FIG. 7  is a simplified schematic of a raster scanning method. 
         FIG. 8  is a simplified schematic of a saw-tooth scanning method. 
         FIG. 9  is a simplified schematic of a serpentine scanning method. 
         FIG. 10  is a simplified schematic of a rotating scanning method. 
         FIG. 11  is a simplified schematic of a scanning method over a portion of the target surface. 
     
    
    
     DETAILED DESCRIPTION 
     The plasmaclave devices described herein address the shortcomings of the typical autoclave or plasma sterilization equipment by providing a solution for sterilizing a set of objects using a plasma, where the plasma spot is smaller than the object to be sterilized. In the equipment and processes described herein the plasma spot (or line) can be scanned across a target area containing objects to be sterilized using magnetic and or electric fields. The plasma can be generated in a vacuum and be higher energy than typical plasma torches. The plasma can also be pulsed. By pulsing the plasma, and scanning it across the target area, the maximum temperature of the objects can be controlled while ensuring that the object is sufficiently sterilized. 
     In some embodiments, a plasmaclave device used to sterilize objects comprises a chamber, and a plasma within the chamber, and the plasma is directed onto the objects in order to sterilize them. In some embodiments, the plasma is pulsed. Using a pulsed plasma is beneficial because the objects being sterilized will not be exposed to the plasma constantly over time, and in between pulses the objects will have time to cool down. In some embodiments, the plasma is spatially scanned across the objects. Using a scanned plasma is beneficial because the whole object will not be exposed to the plasma constantly over time, and will therefore not heat up as much as if the plasma were not scanned. In plasmaclave devices with a scanned plasma, a first portion of the objects being sterilized will be exposed to the plasma, and then the plasma will move, and as the plasma is directed to other portions of the object, the first portion of the object will have time to cool down. The result of using a pulsed and/or scanned plasma for sterilization of an object is that the object will be sufficiently sterilized by the plasma, but the object will not heat up as much as in typical sterilization techniques. 
     In some embodiments, the maximum temperature of the objects being sterilized by the plasmaclave devices described herein is less than or equal to 200° C., or less than or equal to 150° C., or less than or equal to 125° C., or less than or equal to 100° C., or from 50° C. to 200° C., or from 50° C. to 150° C., or from 50° C. to 125° C., or from 50° C. to 100° C., or within any range between a maximum temperature of 200° C., 175° C., 150° C., 125° C. or 100° C. and a minimum temperature of 50° C. 
     In some embodiments, the plasmaclave devices described herein contain a chamber capable of maintaining a vacuum. The pressure inside the chamber can be less than or equal to 10 Torr, or less than or equal to 1 Torr, or less than or equal to 0.1 Torr, or from 0.01 Torr to 10 Torr, or from 0.1 Torr to 10 Torr, or from 0.01 Torr to 1 Torr, or from 0.1 Torr to 1 Torr. 
     In some embodiments, the plasmaclave devices described herein contain a tray within the chamber, and objects to be sterilized are arranged on a target surface of the tray. In some embodiments, the tray within the chamber of the plasmaclave is stationary, or can move. The benefit of a stationary tray is that the sterilization equipment has fewer mechanical parts, which are prone to failure. The use of a scanned plasma with a stationary tray allows for the plasma to be uniformly distributed over the target area of the tray, without a movable tray requiring mechanical parts. In some embodiments, the tray is made from metal (e.g., aluminum or steel), ceramic, glass, plastic, or other appropriate material, depending on the implementation. The tray can be electrically floating, grounded, or biased, in different applications. 
     Plasmas can be generated in a number of ways. It should be appreciated that some of the embodiments described herein can be compatible with different methods of producing plasmas. The plasmaclave devices described herein contain one or more high voltage electrodes disposed within the chamber to generate the plasma. Alternatively, the plasma can be an inductively induced plasma. 
     In some embodiments, the plasmaclave devices described herein contain a plasma that is either a DC plasma or an AC plasma. The AC plasma can have a fundamental frequency from a minimum of 1 or 10 kHz to a maximum of 1 or 1.6 MHz. Additionally, the DC plasma or the AC plasma can be pulsed in some embodiments. The pulsed plasmas described herein can have a cycle repetition frequency from 1 Hz to 1 kHz with a duty cycle or pulse width between 10% and 90%. In some embodiments, the plasmaclave contains a power supply that produces the plasma and has a power level from 10 W to 100 W per 20 square inches of chamber volume. 
     In some embodiments, the spatial distribution of the electrical field within the chamber is influenced by fixed magnets and/or steering coils disposed within the chamber. The fixed magnets are generally used to create magnetic field spatial distributions which are substantially unchanging over time, as described below. The steering coils are generally used to create electric and magnetic field spatial distributions which change over time. 
     In some embodiments, the fixed magnets constrain the plasma within a constrained plasma zone within the chamber. In some embodiments, the constrained plasma zone is adjacent to (or surrounding, or in close proximity to) the target surface of the tray. In some embodiments, the fixed magnets are made of any appropriate magnetic material, such as ferrous materials, rare earth materials, etc. In some embodiments, the fixed magnets are spaced sufficiently to provide a proper constrained plasma zone or field, depending on the size of the chamber. 
     In some embodiments, the steering coils produce electrical and magnetic fields which focus the electrical field to a smaller region within the chamber, thereby creating a further constrained plasma within that smaller region. Additionally, the steering coils are capable of producing electric and magnetic field distributions which change over time, so they can be used to scan the further constrained plasma over the target surface of the stationary tray. In some embodiments, the steering coils are made of any appropriate material, such as magnetic wire, high temperature magnetic wire, litz wire, etc., depending on the implementation. In some embodiments, the steering coils are spaced sufficiently to provide a proper further constrained plasma zone or field, depending on the size of the chamber. 
     The steering coils can employ different techniques for spatially scanning the further constrained plasma across the target surface of the tray. For example, the spatial scanning can be done using a raster pattern method, or a saw-tooth pattern method, or a serpentine pattern method. In the raster, serpentine or saw-tooth scanning methods, a number of scanning rows can be defined over the target area as the number of times the scanning process begins at the first side of the target area. In any spatial scanning method, the scanning rate can be constant over the duration of the scan, or can change. Furthermore, the total number of scans over the object during sterilization (including multiple passes over the same regions) can be changed. The spatial scanning parameters (e.g., the number of scanning rows, the scanning rates over the target area, and the total number of scans over the object during sterilization) can be changed such that the duration of exposure to the plasma during a scan can be changed. The spatial scanning parameters during a scan will in turn influence the degree of sterilization and maximum temperature of the object during sterilization. The scanning parameters are therefore tuned to ensure that the object is sufficiently sterilized and the maximum temperature of the object is kept below a threshold. 
     In some embodiments, the objects or equipment to be sterilized are located in a portion of the target surface. The further constrained plasma is, thus, scanned over the portion of the target surface containing the objects or equipment to be sterilized. 
     In another embodiment, the high voltage electrodes used to generate the plasma are physically moved to control the distribution of the electric field within the chamber. Additionally, the electric field can be focused in certain areas as the electrodes move, which will further constrain the plasma in those areas. The movement of the electrodes can in turn cause the further constrained plasma to be scanned over the target area, or a portion of the target area. In some embodiments, the electrodes are moved by rotating the electrodes using a motor. In some embodiments, the electrodes are moved in different lateral directions, for example by using a gantry system. In some embodiments, the electrodes are moved back and forth above the target surface to uniformly cover the area containing in the objects to be sterilized with the further constrained plasma. 
     In some embodiments, a temperature sensor is included, which monitors the temperature of the objects being sterilized. The temperature sensor can be used as feedback to control the plasma parameters (e.g., the power, the frequency, the pulse parameters), or the scanning parameters. This is advantageous, because the active feedback will ensure that the maximum temperature of the object is kept below a predetermined threshold. 
     Plasmaclave Device Embodiments 
       FIGS. 1A, 1B, and 2-6  show example low-cost, small-size plasmaclave devices  100 ,  300  and  500  in accordance with some embodiments. The plasmaclave devices  100 ,  300  and  500  use a plasma to sterilize any objects or equipment (e.g., medical instruments, surgical devices, food preparation utensils, tattoo devices, etc.) placed inside the plasmaclave devices  100 ,  300  and  500 . The temperature to which the objects are heated during the plasmaclave process using these devices is considerably lower than that which occurs during an autoclave process, yet the objects are nevertheless properly sterilized. Usage of the plasmaclave devices  100 ,  300  and  500 , thus, presents considerably less potential hazards for the operators of the devices  100 ,  300  and  500 . 
     As shown in  FIG. 1A , the example plasmaclave device  100  generally includes a housing  101 , a power input  102 , an inert gas input  103 , a door  104 , a control/display panel  105 , a control circuit  106 , steering coils (e.g., magnetic field coils)  107 , a fixed magnet (e.g., a shutter field coil)  108 , a high voltage electrode  109 , and a tray table (i.e., tray)  110 , among other components not shown for simplicity. The door  104  provides access to the interior of the housing  101 . The “interior of the housing” is also referred to herein as the “chamber”, or the “plasma glow chamber”. 
     The geometry of the electrodes and other elements disposed within the chamber can vary in different embodiments. In some embodiments, as shown in  FIG. 1B , a plasmaclave device  120  generally includes a housing  121 , an inert gas input  123 , a door  124 , a control/display panel  125 , a control circuit  126 , steering coils (e.g., magnetic field coils)  127 , a fixed magnet (e.g., a shutter field coil)  128 , a high voltage anode electrode  129 , a tray table (i.e., tray)  130 , and a cylindrical cathode ground return electrode  131  (also the “chamber”), among other components not shown for simplicity. The high voltage anode electrode  129  is located within and concentric with the cylindrical cathode ground return electrode  131 . For example, as shown in  FIG. 1B , the high voltage anode electrode  129  can be a linear electrode surrounded by the cylindrical cathode ground return electrode  131 , which serves as the chamber in this embodiment. In such embodiments, and as shown in  FIG. 1B , the tray  130  can be located in the space between the high voltage anode electrode  129  and the cylindrical cathode ground return electrode  131 . The figure also shows that the fixed magnet  128  and steering coils  127  can be located in positions to affect the electric and magnetic fields and constrain the plasma to a region within the target surface on the tray  130  where the objects  111  are placed. For example, the fixed magnets  128  and/or steering coils  127  could be located on either side of the high voltage anode electrode  129  and between the high voltage anode electrode  129  and the tray  130 . 
     As further shown in  FIG. 2 , the example plasmaclave device  100  (or  120 ) further includes a DC power adapter  201 , an on/off start switch  202 , a circuit board  203 , a vacuum pump  204 , a pressure sensor  205 , the inert gas input  103  (or  123 ), a plasma glow chamber  206  (i.e., the chamber), and a plasma glow ground return  207 , among other components not shown for simplicity. The circuit board  203  (i.e., the control circuit  106  or  126 ) further includes a microcontroller  208 , a DC to DC low voltage converter  209 , a DC to DC high voltage converter  210 , a high side/low side MOSFET driver  211 , a high voltage current limiting element  212 , a high voltage/high frequency inductive coil  213 , high voltage/high frequency resonance capacitors  214 , and a bias field power supply  215 , among other components not shown for simplicity. The plasma glow chamber  206  generally contains one or more plasma glow blade electrodes  216  (i.e., the high voltage electrode  109  or  129 ) and the tray  110  (or  130 ) therein, among other components not shown for simplicity. The tray  110  (or  130 ) is used to hold the objects  111  for sterilization. The tray  110  (or  130 ) can be electrically floating, grounded, or biased, in different applications. 
     The power input  102  (not shown in  FIG. 2 ) provides electrical power (e.g., AC power) to the DC power adapter  201 , which powers the electrical components (e.g., the control/display panel  105  or  125 , the control circuit  106  or  126 , the steering coils  107  or  127 , the fixed magnet  108  or  128 , the high voltage electrode  109  or  129 , the circuit board  203 , the vacuum pump  204 , and the pressure sensor  205 , etc.). The inert gas input  103  (or  123 ) enables an inert gas to flow into the interior of the housing  101  (or  121 ) for the plasma to be generated in the inert gas within the plasma glow chamber  206 . 
     The DC power adapter  201  receives AC input power from the power input  102  and provides electrical power to the DC to DC low voltage converter  209 . The DC to DC low voltage converter  209  converts the electrical power and provides the necessary current at an appropriate voltage level to the microcontroller  208  and to the DC to DC high voltage converter  210 . The microcontroller  208  receives an on/off signal from the on/off start switch  202  to control when to turn on other components. The microcontroller  208  provides control signals to the DC to DC high voltage converter  210 , the vacuum pump  204 , and the bias field power supply  215 , among other components. The DC to DC high voltage converter  210  (powered by the DC to DC low voltage converter  209 , and under control of the microcontroller  208 ) provides a high voltage level to the high side/low side MOSFET driver  211 , which provides electrical power to the high voltage/high frequency inductive coil  213 . The high side/low side MOSFET driver  211  also provides a signal to the high voltage current limiting element  212 , which provides feedback to the microcontroller  208  for controlling the DC to DC high voltage converter  210 . The high voltage/high frequency inductive coil  213  provides electrical power to the plasma glow array blade electrodes  216  and the high voltage/high frequency resonance capacitors  214 . The high voltage/high frequency resonance capacitors  214 , in conjunction with the high voltage/high frequency inductive coil  213 , create an LC resonant tank to generate the resonance for the high voltage applied to the plasma glow array blade electrodes  216 . The bias field power supply  215  provides a bias potential to the tray  110 . (Although not shown in  FIGS. 4 and 6 , a similar bias field power supply may provide a bias potential to the trays  309  and  510  described below.) 
     To perform a plasmaclave treatment on various objects  111 , the door  104  (or  124 ) is opened by an operator of the plasmaclave device  100  (or  120 ), and the objects  111  are inserted into the interior of the housing  101  (or  121 ) and placed onto the tray table  110  (or  130 ). The door  104  (or  124 ) is then securely closed. The control/display panel  105  (or  125 ) (e.g., control buttons, an LCD display, etc.) is used to set a time period for performing, and/or to start and stop, the plasmaclave treatment. The control panel/display panel  105  (or  125 ) is also used to set other parameters (e.g., scanning parameters, plasma power parameters, inert gas flow, pressure, etc.) for the process in different embodiments. 
     When the plasmaclave treatment is started, the air inside the housing  101  (or  121 ) is pumped out using the vacuum pump  204  (under control of the microcontroller  208 ) until the pressure sensor  205  indicates that the pressure in the plasma glow chamber  206  is sufficiently low. The pressure sensor  205  can be used as a safety interlock control input, where the process is not continued (e.g., the inert gas flow is not started, the high voltage is not delivered to the blade electrodes, etc.) until a sufficiently low pressure is reached within the chamber. Once the pressure is sufficiently low, then the inert gas is flowed into the interior of the housing (i.e., the chamber)  101  (or  121 ). Then the plasma glow array blade electrodes  216  receive power, as described above to generate a plasma in the inert gas in the chamber. In some embodiments, the plasma is generated in a plasma region or zone generally between the high voltage electrode  109  (or  129 ) and the tray table  110  (or  130 ). In some embodiments, the plasma glow chamber  206  is grounded through the plasma glow ground return  207  to complete the circuit to the DC power adapter  201  and to help direct the plasma. The fixed magnet  108  (or  128 ) controls and intensifies the electric field, which in turn creates a higher density plasma in a constrained plasma zone within the chamber.  FIG. 1A  (or  1 B) shows the fixed magnet  108  (or  128 ) arranged adjacent to the high voltage electrodes  109  (or  129 ). However, in different embodiments, other fixed magnets can be distributed in other locations around the chamber such that the electric field is focused and the plasma is constrained in a selected constrained plasma zone. In some embodiments, the constrained plasma zone is located adjacent to the tray  110  (or  130 ), where the objects  111  to be sterilized are located. The steering coils  107  (or  127 ) are operated to further control where the electric field is focused and further constrain the plasma. The further constrained plasma can then be scanned over a target surface over the tray table  110  (or  130 ), thereby sterilizing the objects  111 . In some embodiments, the further constrained plasma is scanned throughout the extent of the tray table  110  (or  130 ), while in other embodiments, the further constrained plasma is scanned over a portion of the tray table  110  (or  130 ). 
     When the plasmaclave treatment is finished, the power to the steering coils  107  (or  127 ), the fixed magnet  108  (or  128 ), and the high voltage electrode  109  (or  129 ) is turned off. Then the inert gas is optionally flushed from the interior of the housing  101  (or  121 ). After the chamber is vented to atmosphere, the door  104  (or  124 ) can be opened and the objects  111  removed. 
     As shown in  FIG. 3 , the example plasmaclave device  300  generally includes a housing  301 , a power input  302 , an inert gas input  303 , a door  304 , a control/display panel  305 , a control circuit  306 , a series of steering coils (e.g., high voltage cascade raster coils)  307 , a series of high voltage electrodes (e.g., blade electrodes)  308 , and a tray  309 , among other components not shown for simplicity. The door  304  provides access to the interior of the housing  301 , i.e., the chamber, the plasma chamber, or the plasma glow chamber. As further shown in  FIG. 4 , the example plasmaclave device  300  further includes a DC power adapter  401 , an on/off start switch  402 , a circuit board  403 , a vacuum pump  404 , a pressure sensor  405 , the inert gas input  303 , a plasma glow chamber  406 , and a plasma glow ground return  407 , among other components not shown for simplicity. The circuit board  403  (i.e., the control circuit  306 ) further includes a microcontroller  408 , a DC to DC low voltage converter  409 , a DC to DC high voltage converter  410 , a high side/low side MOSFET driver  411 , a high voltage current limiting element  412 , a high voltage/high frequency inductive coils array  413 , a high voltage/high frequency resonance capacitors array  414 , and a cascade raster multiplexer  415 , among other components not shown for simplicity. The plasma glow chamber  406  generally contains plasma glow array blade electrodes  416  (i.e., the high voltage electrodes  308 ) and the tray  309  therein, among other components not shown for simplicity. The tray  309  is used to hold the objects for sterilization. The tray  309  can be electrically floating, grounded, or biased, in different applications. 
     The power input  302  provides electrical power (e.g., AC power) to the DC power adapter  401 , which powers the electrical components (e.g., the control/display panel  305 , the control circuit  306 , the steering coils  307 , high voltage electrodes  308 , the circuit board  403 , the vacuum pump  404 , and the pressure sensor  405 , etc.). The inert gas input  303  enables an inert gas to flow into the interior of the housing  301  for the plasma to be generated in the inert gas within the plasma glow chamber (i.e., the chamber)  406 . 
     The DC power adapter  401  receives AC input power from the power input  302  (not shown in  FIG. 4 ) and provides electrical power to the DC to DC low voltage converter  409 . The DC to DC low voltage converter  409  converts the electrical power and provides the necessary current at an appropriate voltage level to the microcontroller  408  and to the DC to DC high voltage converter  410 . The microcontroller  408  receives an on/off signal from the on/off start switch  402  to control when to turn on other components. The microcontroller  408  provides control signals to the DC to DC high voltage converter  410 , the vacuum pump  404 , and the cascade raster multiplexer  415 , among other components. The DC to DC high voltage converter  410  (powered by the DC to DC low voltage converter  409 , and under control of the microcontroller  408 ) provides a high voltage level to the high side/low side MOSFET driver  411 , which provides electrical power to the high voltage/high frequency inductive coils array  413 . The high side/low side MOSFET driver  411  also provides a signal to the high voltage current limiting element  412 , which provides feedback to the microcontroller  408  for controlling the DC to DC high voltage converter  410 . The high voltage/high frequency inductive coils array  413  provides electrical power to the plasma glow array blade electrodes  416  and the high voltage/high frequency resonance capacitors array  414 . The high voltage/high frequency resonance capacitors array  414  also receive control signals from the cascade raster multiplexer  415 . The high voltage/high frequency resonance capacitors array  414 , in conjunction with the high voltage/high frequency inductive coils array  413 , create an LC resonant tank to generate the resonance for the high voltage applied to the plasma glow array blade electrodes  416 . 
     To perform a plasmaclave treatment on various medical instruments  310 , the door  304  is opened by an operator of the plasmaclave device  300 , and the medical instruments  310  are inserted into the interior of the housing  301  and placed onto the tray table  309 . The door  304  is then securely closed. The control/display panel  305  (e.g., control buttons, an LCD display, etc.) is used to set a time period for performing, and/or to start and stop, the plasmaclave treatment. The control panel/display panel  305  is also used to set other parameters (e.g., scanning parameters, plasma power parameters, inert gas flow, pressure, etc.) for the process in different embodiments. 
     When the plasmaclave treatment is started, the air inside the housing  301  is pumped out using the vacuum pump  404  (under control of the microcontroller  408 ) until the pressure sensor  405  indicates that the pressure in the plasma glow chamber  406  is sufficiently low. The pressure sensor  405  can be used as a safety interlock control input, where the process is not continued (e.g., the inert gas flow is not started, the high voltage is not delivered to the blade electrodes, etc.) until a sufficiently low pressure is reached within the chamber. Once the pressure is sufficiently low, then the inert gas is flowed into the interior of the housing (i.e., the chamber)  301 . Then the plasma glow array blade electrodes  416  receive power, as described above to generate a plasma in the inert gas in the chamber. In some embodiments, the plasma is generated in a plasma region or zone generally between the high voltage electrodes  308  and the tray table  309 . In some embodiments, the plasma glow chamber  406  is grounded through the plasma glow ground return  407  to complete the circuit to the DC power adapter  401  and to help direct the plasma. In some embodiments, one or more fixed magnets (not shown in  FIG. 3 ) control and intensify the electric field, which in turn creates a higher density plasma in a constrained plasma zone within the chamber. These fixed magnets are shutter field coils surrounding the high voltage electrodes  308 , in some embodiments. In other embodiments, other fixed magnets can be distributed in other locations around the chamber such that the electric field is focused and the plasma is constrained in a selected constrained plasma zone. In some embodiments, the constrained plasma zone is located adjacent to the tray, where the objects to be sterilized are located. The steering coils  307  are operated to further control where the electric field is focused and further constrain the plasma. The further constrained plasma can then be scanned over a target surface over the tray table  309 , thereby sterilizing the objects  310 . In some embodiments, the electrical signals from the control circuit  306  are applied in a rapid raster scan pattern to the high steering coils  307 , so that the further constrained plasma is rapidly scanned over a target surface of the tray table  309 , thereby sterilizing the medical instruments  310 . In some embodiments, the further constrained plasma is scanned throughout the extent of the tray table, while in other embodiments, the further constrained plasma is scanned over a portion of the tray table. 
     When the plasmaclave treatment is finished, the power to the steering coils  307  and the high voltage electrodes  308  is turned off. Then the inert gas is optionally flushed from the interior of the housing  301 . After the chamber is vented to atmosphere, the door  304  can then be opened and the objects  310  removed. 
     As shown in  FIG. 5 , the example plasmaclave device  500  generally includes a housing  501 , a power input  502 , an inert gas input  503 , a door  504 , a control/display panel  505 , a control circuit  506 , a high voltage coil  507 , a motor  508 , a high voltage electrode (e.g., a blade electrode)  509 , and a tray table  510 , among other components not shown for simplicity. The door  504  provides access to the interior of the housing  501 , i.e., the chamber, the plasma chamber, or the plasma glow chamber. As further shown in  FIG. 6 , the example plasmaclave device  500  further includes a DC power adapter  601 , an on/off start switch  602 , a circuit board  603 , a vacuum pump  604 , a pressure sensor  605 , the inert gas input  503 , a plasma glow chamber (i.e., the chamber)  606 , and a plasma glow ground return  607 , among other components not shown for simplicity. The circuit board  603  (i.e., the control circuit  506 ) further includes a microcontroller  608 , a DC to DC low voltage converter  609 , a DC to DC high voltage converter  610 , a high side/low side MOSFET driver  611 , a high voltage current limiting element  612 , a high voltage/high frequency inductive coil  613 , high voltage/high frequency resonance capacitors  614 , and a motor electrode blade spin drive  615 , among other components not shown for simplicity. The plasma glow chamber (i.e., the chamber)  606  generally contains plasma glow array blade electrodes  616  (i.e., the high voltage electrode  509 ) and the tray table (i.e., the tray)  510  therein, among other components not shown for simplicity. The tray  510  is used to hold the objects (e.g., dental, medical instruments) for sterilization. The tray can be electrically floating, grounded, or biased, in different applications. 
     The power input  502  provides electrical power (e.g., AC power) to the DC power adapter  601 , which powers the electrical components (e.g., the control/display panel  505 , the control circuit  506 , the high voltage coil  507 , the motor  508 , the high voltage electrode  509 , the circuit board  603 , the vacuum pump  604 , and the pressure sensor  605 , etc.). The inert gas input  503  enables an inert gas to flow into the interior of the housing (i.e., the chamber)  501  for the plasma to be generated in the inert gas within the plasma glow chamber (i.e., the chamber)  606 . 
     The DC power adapter  601  receives AC input power from the power input  502  and provides electrical power to the DC to DC low voltage converter  609 . The DC to DC low voltage converter  609  converts the electrical power and provides the necessary current at an appropriate voltage level to the microcontroller  608  and to the DC to DC high voltage converter  610 . The microcontroller  608  receives an on/off signal from the on/off start switch  602  to control when to turn on other components. The microcontroller  608  provides control signals to the DC to DC high voltage converter  610 , the vacuum pump  604 , and the motor electrode blade spin drive  615 , among other components. The DC to DC high voltage converter  610  (powered by the DC to DC low voltage converter  609 , and under control of the microcontroller  608 ) provides a high voltage level to the high side/low side MOSFET driver  611 , which provides electrical power to the high voltage/high frequency inductive coil  613 . The high side/low side MOSFET driver  611  also provides a signal to the high voltage current limiting element  612 , which provides feedback to the microcontroller  608  for controlling the DC to DC high voltage converter  610 . The high voltage/high frequency inductive coil  613  provides electrical power to the plasma glow array blade electrodes  616  and the high voltage/high frequency resonance capacitors  614 . The high voltage/high frequency resonance capacitors  614  also receive control signals from the motor electrode blade spin drive  615 . 
     To perform a plasmaclave treatment on various objects  511 , the door  504  is opened by an operator of the plasmaclave device  500 , and the objects  511  are inserted into the interior of the housing (i.e., chamber)  501  and placed onto the tray table (i.e., tray)  510 . The door  504  is then securely closed. The control/display panel  505  (e.g., control buttons, an LCD display, etc.) is used to set a time period for performing, and/or to start and stop, the plasmaclave treatment. The control panel/display panel  505  is also used to set other parameters (e.g., scanning parameters, plasma power parameters, inert gas flow, pressure, etc.) for the process in different embodiments. 
     When the plasmaclave treatment is started, the air inside the housing  501  is pumped out using the vacuum pump  604  (under control of the microcontroller  608 ) until the pressure sensor  605  indicates that the pressure in the plasma glow chamber  606  is sufficiently low. The pressure sensor  605  can be used as a safety interlock control input, where the process is not continued (e.g., the inert gas flow is not started, the high voltage is not delivered to the blade electrodes, etc.) until a sufficiently low pressure is reached within the chamber. Once the pressure is sufficiently low, then the inert gas is flowed into the interior of the housing (i.e., the chamber)  501 . Then the plasma glow array blade electrodes  616  receive power, as described above to generate a plasma in the inert gas in the chamber. In some embodiments, the plasma is generated in a plasma region or zone generally between the high voltage electrodes  509  and the tray table  510 . In some embodiments, the plasma glow chamber  606  is grounded through the plasma glow ground return  607  to complete the circuit to the DC power adapter  601 . In some embodiments, one or more fixed magnets (not shown in  FIG. 5 ) control and intensify the electric field, which in turn creates a higher density plasma in a constrained plasma zone within the chamber. These fixed magnets are shutter field coils surrounding the high voltage electrodes, in some embodiments. In other embodiments, other fixed magnets can be distributed in other locations around the chamber such that the electric field is focused and the plasma is constrained in a selected constrained plasma zone. In some embodiments, the constrained plasma zone is located adjacent to the tray, where the objects to be sterilized are located. The motor  508  is operated to rotate the high voltage electrode, thereby further controlling where the electric field is distributed and further constraining the plasma. As the motor rotates the high voltage electrodes, the further constrained plasma is scanned over the target surface over the tray table  510 , thereby sterilizing the objects  511 . 
     When the plasmaclave treatment is finished, the power to the high voltage coil  507 , the motor  508 , and the blade electrode  509  is turned off. Then the inert gas is optionally flushed from the interior of the housing  501 . After the chamber is vented to atmosphere, the door  504  can then be opened and the medical instruments  511  removed. 
     Plasmaclave Device Scanning Methods 
       FIG. 7  shows a rastering method for scanning the plasma over a target surface  701 . In this rastering method, an electric field is generated by a high voltage electrode  702 , which generates a plasma. Steering coils  703  create additional electric and magnetic field spatial distributions which change over time as illustrated by dashed arrows  704 , resulting in a higher density plasma focused in a spot which changes location over time. The size of this “plasma spot” can vary from nearly the same size as the tray to very small (e.g., 0.01 times the area of the tray, or 0.001 times the area of the tray). In the rastering method, the steering coils first scan the plasma spot in a direction from a first side of the target surface to a second side of the target surface  701  (as indicated by large arrows  705 ) at a first scanning rate, and then return (as indicated by dashed arrows  706 ) to the first side of the target surface at a second scanning rate which is faster than the first scanning rate, before starting the sequence again. A time period for completing a scan cycle may be between 0.1 second and 1 second per cycle. 
       FIG. 7  shows a first motion (at first large arrow  705 ) of the plasma spot in a direction along vector A, from a first side of the target surface  701  to a second side of the target surface  701 . Then the plasma spot is quickly scanned (along dashed arrow  706 ) back to the first side of the target surface  701  to start a second row (at second large arrow  705 ) that is translated in the direction B. By stepping each scan in the direction B, the whole target surface will eventually be covered after a certain number of scans. This number of scans can be 5, 10, 20, 50, 100, 500, 1000, or from 5 to 1000, or from 5 to 500, or from 5 to 100, or from 5 to 50, or from 5 to 20. Generally, the magnitude of the vector B in  FIG. 7  (i.e., the distance between scans in the B direction) is chosen such that it is equal to or less than the of the size of the plasma spot. It is understood that the plasma spot will have some peaked distribution, and the “size” of the spot can be defined by the full-width at half maximum of the peak. If the return speed from the second side of the target surface  701  to the first side of the target surface  701  is much faster than the first scanning speed, then the rastering method is relatively efficient. 
       FIG. 8  shows a saw-tooth method for scanning the plasma over a target surface  801 . Similar to the rastering method described above, an electric field is generated by a high voltage electrode, which generates a plasma. Steering coils create additional electric and magnetic field spatial distributions which change over time, resulting in a higher density plasma focused in a spot which changes location over time. The size of this “plasma spot” can vary from nearly the same size as the tray to very small (e.g., 0.01 times the area of the tray, or 0.001 times the area of the tray). In the saw-tooth method, the steering coils scan the plasma spot in a direction from a first side to a second side of the target surface  801  at a slight angle (e.g., as illustrated by large arrow  803 ) and at a first scanning rate, and then scan from the second side back to the first side at a slight angle (e.g., as illustrated by large arrow  804 ) and at the first scanning rate, before starting the scanning sequence again. The slight angles can be chosen to cover the whole target surface with a certain number of scans. A time period for completing a scan cycle may be between 0.1 second and 1 second per cycle. 
       FIG. 8  shows a first motion of the plasma spot (in the direction of arrow  803 ) in a diagonal direction along the sum of vector A and vector B, from a first side of the target surface  801  to a second side of the target surface  801 . Then the plasma spot is scanned back to the first side of the target surface  801  in a diagonal direction (arrow  804 ) along the sum of the negative of the vector A and vector B. Each scan ends farther down the target surface in the direction B, and the whole target surface will eventually be covered after a certain number of scans. This number of scans can be 5, 10, 20, 50, 100, 500, 1000, or from 5 to 1000, or from 5 to 500, or from 5 to 100, or from 5 to 50, or from 5 to 20.  FIG. 8  also shows the plasma spot size  802 . Generally, the magnitude of the vector B in  FIG. 8  (i.e., the distance between the beginning of scans in the B direction) is chosen such that it is equal to or less than the of the size of the plasma spot. It is understood that the plasma spot will have some peaked distribution, and the “size” of the spot can be defined by the full-width at half maximum of the peak. One advantage of the saw-tooth method is that there is only one scanning speed needed. One disadvantage is that the angled scans create target areas that are covered by the plasma spot more often and regions that are covered by the plasma spot less often. 
       FIG. 9  shows a serpentine method for scanning the plasma over the target surface  901 . Similar to the rastering method described above, an electric field is generated by a high voltage electrode, which generates a plasma. Steering coils create additional electric and magnetic field spatial distributions which change over time, resulting in a higher density plasma focused in a spot which changes location over time. The size of this “plasma spot” can vary from nearly the same size as the tray to very small (e.g., 0.01 times the area of the tray, or 0.001 times the area of the tray). In the serpentine method, steering coils scan the plasma in a direction from a first side to a second side of the target surface  901  at a first scanning rate (along arrow  903 ), and then step to a new row (along arrow  904 ), and scan from the second side of the target surface  901  back to the first side of the target surface  901  at the first scanning rate (along arrow  905 ), before starting the scanning sequence again. A time period for completing a scan cycle may be between 0.1 second and 1 second per cycle. 
       FIG. 9  shows a first motion of the plasma spot (arrow  903 ) in a direction along vector A, from a first side of the target surface  901  to a second side of the target surface  901 . Then the plasma spot is quickly scanned (arrow  904 ) in the direction of the vector B to start a second row that is translated down the target area. Then the plasma is scanned (arrow  905 ) in the negative of the direction A. By stepping each scan in the direction B, the whole target surface will eventually be covered after a certain number of scans. This number of scans can be 5, 10, 20, 50, 100, 500, 1000, or from 5 to 1000, or from 5 to 500, or from 5 to 100, or from 5 to 50, or from 5 to 20. Generally, the magnitude of the vector B in  FIG. 9  (i.e., the distance between scans in the B direction) is chosen such that it is equal to or less than the of the size of the plasma spot. It is understood that the plasma spot will have some peaked distribution, and the “size” of the spot can be defined by the full-width at half maximum of the peak. One advantage of the serpentine method is that one scanning speed can be used, and the target area will be relatively uniformly covered by the plasma spot. 
       FIG. 10  shows a rotating line method for scanning the plasma over the target surface  1001 . Similar to the rastering method described above, an electric field is generated by a high voltage electrode  1002 , which generates a plasma. In this method, the high voltage electrode creates an electric field that is in the shape of a line. Steering coils  1003  create additional electric and magnetic field spatial distributions which change over time as illustrated by dashed arrows  1004 , resulting in a higher density plasma focused in a line  1005  which changes location over time. The length of this “plasma line”  1005  is roughly the same length as the target area, and the width of the line can vary from nearly the same size as the tray to very small (e.g., 0.01 times the area of the tray, or 0.001 times the area of the tray). In the rotating line method, steering coils rotate the plasma line to cover the whole target area. Alternatively, the electrode  1002  producing a plasma line could itself be rotated (e.g., by a motor), and produce a similar rotating plasma line. One disadvantage of this method is the corners of the target area will not be covered by the plasma line. A time period for completing a scan cycle may be between 0.1 second and 1 second per cycle. 
       FIG. 11  shows an example of a method for scanning the plasma over the target surface  1101 , where a portion  1102  of the target surface  1101  is covered by the plasma. In this example, the objects to be sterilized are all placed within the area portion  1102 , and therefore it is sufficient to scan the plasma over area portion  1102 , and there is no need to scan the plasma over the whole target surface  1101 .  FIG. 11  illustrates covering a portion of the target surface using a serpentine scan, however any scanning method could be used to cover a portion of a target surface in other embodiments. A time period for completing a scan cycle may be between 0.1 second and 1 second per cycle. 
     Although embodiments of the present invention have been discussed primarily with respect to specific embodiments thereof, other variations are possible. Various configurations of the described system may be used in place of, or in addition to, the configurations presented herein. For example, additional components may be included in circuits where appropriate. As another example, configurations were described with general reference to certain types and combinations of circuit or system components, but other types and/or combinations of circuit components could be used in addition to or in the place of those described. 
     Those skilled in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the present invention. Nothing in the disclosure should indicate that the present invention is limited to systems that have the specific type of devices shown and described. Nothing in the disclosure should indicate that the present invention is limited to systems that require a particular form of integrated circuits or hardware components, except where specified. In general, any diagrams presented are only intended to indicate one possible configuration, and many variations are possible. Those skilled in the art will also appreciate that methods and systems consistent with the present invention are suitable for use in a wide range of applications. 
     While the specification has been described in detail with respect to specific embodiments of the present invention, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these embodiments. These and other modifications and variations to the present invention may be practiced by those skilled in the art, without departing from the scope of the present invention.