Patent Publication Number: US-2012039747-A1

Title: Treating device for treating a body part of a patient with a non-thermal plasma

Description:
FIELD OF THE INVENTION 
     The invention relates to a treating device for treating a body part of a patient with a non-thermal plasma, particularly for sterilizing a hand of a human being. 
     BACKGROUND OF THE INVENTION 
     The use of non-thermal plasma for the treatment of wounds and especially for the in-vivo sterilization, decontamination or disinfection of wounds is disclosed, for example, in WO 2007/031250 A1, EP 1 925 190 A1 and PCT/EP2008/003568. However, the known devices for plasma treatment are suitable to only a limited extent for the in-vivo sterilization of a hand of a human being. WO 02/099836 A1 describes an apparatus and method using capillary discharge plasma shower for sterilizing and disinfecting articles. However, also this apparatus is suitable to only a limited extend for the in-vivo sterilization of a hand, in particular due to the turbulences caused by the shower. Also, the sterilizing and disinfection ability of this device is limited by the copious amounts of reactive gases introduced into the atmosphere—which may lead to health hazards. 
     SUMMARY OF THE INVENTION 
     Therefore, it is a general object of the invention to provide a treating device which is suitable for the in-vivo sterilization of a hand of a human being. 
     This object is achieved by a novel treating device according to the main claim. 
     The treating device according to the invention comprises a housing for temporarily receiving a body part which is to be sterilized within the housing during the treatment and for applying the non-thermal plasma to the body part within the housing. Therefore, the treating device according to the invention is different in nature from conventional treating devices in which the object of the treatment (e.g. a hand) is located outside a plasma applicator so that the plasma applicator must be moved along the surface of the object of treatment so that the non-thermal plasma is applied to the entire surface of the object of treatment. In other words, in conventional treating devices the non-thermal plasma is applied to the object of treatment while the invention provides that the object of treatment (e.g. a hand of a human being) is introduced into the non-thermal plasma so that the object of treatment is completely surrounded by the non-thermal plasma. 
     The housing of the treating device according to the invention comprises an inlet opening for introducing the body part (e.g. a hand of a human being) through the inlet opening into the housing so that the plasma treatment takes place within the housing. 
     The treating device according to the invention is particularly suitable for the in-vivo sterilization of a hand of a human being. However, the treating device according to the invention can also be used for the plasma treatment of other body parts of a patient, e.g. a foot or a forearm including a hand and preferably further including an elbow of a human being. Furthermore, the object of treatment can be a non-biological article like a surgical instrument, an implant, for example a heart pacemaker, a stent, an artificial joint, or other devices to be sterilized. 
     Further, the treating device according to the invention preferably comprises an integrated plasma generator for generating the non-thermal plasma within the housing. Therefore, the plasma generator is preferable an integral part of the treating device. 
     Alternatively, it is possible that the treating device merely comprises an inlet for introducing the plasma into the housing wherein the plasma is generated outside the housing by a separate plasma generator which can be connected with the inlet of the treating device via a hose. 
     In a preferred embodiment of the invention, the plasma generator comprises at least two electrodes and a barrier between the electrodes, so that the plasma is generated between the electrodes by a dielectric barrier discharge (DBD), which is per se known in the state of the art. Therefore, the barrier between the electrodes preferably consists of an electrically insulating and/or dielectric material, particularly polytetraflouroethylene. 
     Further, the electrodes can be adhered to the barrier on opposite sides of the barrier. 
     The at least two electrodes can be provided in a plurality of manners. For example, at least one of the electrodes can be provided as a single wire. Preferably, at least one of the electrodes is provided spirally, or wound, or flat, or like a cooling coil, or in a meandering manner. 
     At least one of the electrodes can comprise several perforations, which are distributed over the electrode. Therefore, the plasma can be produced within the perforations of the electrode. 
     Preferably, at least one of the first electrode and the second electrode comprises a wire-mesh, wherein the afore-mentioned perforations are arranged between individual meshes of the wire-mesh. In other words, each mesh of the wire-mesh forms one of the afore-mentioned perforations. One advantage of such an arrangement is that it is scalable, adaptive and can be customized to any form and shape thereby allowing new applications, e.g. as a wound dressing. Further, such an electrode arrangement is easy to manufacture and very cost effective. Unlike conventional dielectric barrier devices proposed for plasma medicine, it does not pass a current through human tissue. Moreover, a double mesh system can be gas permeable so that a gas flow can transversely penetrate the electrode arrangement so that it is useful for air purification, sterilization and pollution (exhaust) control. 
     Further, it is possible to arrange several of the afore-mentioned double-mesh electrode systems at distances of a few centimeters, wherein the double-mesh systems are preferably aligned parallel to each other. 
     In another embodiment, at least one of the first electrode and the second electrode comprises a perforated plate in which the afore-mentioned perforations are arranged. For example, the plate can be made of copper or aluminium wherein the perforations in the plate are punched out of the plate. Further, it is possible that both electrodes of the electrode arrangement consist of perforated plates, which are separated by the dielectric barrier. 
     In yet another embodiment, at least one of the first and second electrodes consists of parallel wires or stripes made of an electrically conductive material. 
     It should further be noted that in the afore-mentioned embodiments, the perforations are preferably equally distributed over the electrode surface so that the intensity of the plasma generation is also equally distributed over the surface of the electrode. 
     In one embodiment, the first electrode comprises a plate made of an electrically conductive material, wherein the plate is preferably massive and does not comprise any perforations. The dielectric barrier is substantially layer-shaped and formed on a surface of the plate. For example, the dielectric barrier can have a thickness in the range of 0.5-1 mm. In this embodiment, the second electrode comprises either the afore-mentioned wire-mesh or a perforated plate made of an electrically conductive material. The first electrode formed as a massive plate is preferably energized with an alternating current with a voltage of 10-20 kV and a typical electrical current of 10-30 mA while the second electrode formed as a wire-mesh is preferably electrically grounded. 
     In another embodiment, both the first electrode and the second electrode comprise a wire-mesh while the dielectric barrier comprises a cladding made of an electrically insulating and dielectric material surrounding the wires of at least one of the first electrode and the second electrode thereby electrically insulating the first electrode from the second electrode. In other words, the electrically insulating and dielectric cladding of the individual wires of the wire-mesh forms the dielectric barrier. The first electrode and the second electrode are attached to each other, preferably by an adhesive bond, so that the wire-meshes of the first and second electrodes are contacting each other physically. 
     In one variant of this embodiment, both the first electrode and the second electrode comprise a cladding surrounding the individual wires of the wire-mesh thereby forming the dielectric barrier. 
     In another variant of this embodiment, merely one of the first and second electrodes comprises a cladding surrounding the individual wires of the wire-mesh thereby forming the dielectric barrier. In other words, only one of the first and second electrodes is electrically insulated by a cladding while the other one of the first and second electrodes is not insulated by a cladding. 
     It should further be noted that the invention is not restricted to embodiments comprising just two electrodes. For example, it is possible to provide a third electrode and a further dielectric barrier so that there are two dielectric barrier discharge arrangements on both sides of a centre electrode thereby forming a sandwich-like arrangement. 
     It has already been mentioned that the electrodes are preferably adhered to each other. It is also possible that the dielectric barrier is adhered to at least one of the first and second electrodes. 
     Preferably, the electrode arrangement is substantially two-dimensional, flat and deformable so that the shape of the entire electrode arrangement can be adapted to the contour of a body part, which is to be treated. 
     In another embodiment, the electrode arrangement further comprises a cover which is covering the electrode arrangement. The cover can be adapted to increase the local density of the reactive species of the plasma thereby reducing the time needed for sterilization. Further, the cover can be adapted to filter out unused reactive species. It is further possible to adapt the cover to effect a better control of the plasma. Finally, the cover can be adapted so that the electrode arrangement can operate under reduced pressure. 
     The dielectric barrier may consist of an electrically insulating and dielectric material. The dielectric barrier preferably consists of ceramics if high performance is desired. Alternatively, the dielectric barrier can be made of polytetrafluoroethylene if a lower performance of the electrode arrangement is sufficient. Further, the dielectric barrier can be made of polyethylene terephtalate (PET), flexible or rigid glass-ceramic, glas, Mylar®, casting ceramic or oxides. However, the melting point of the dielectric material should preferably be over +100° C. 
     It should further be noted that the invention is not restricted to an electrode arrangement as a single component. The invention rather comprises a complete apparatus for plasma treatment comprising the afore-mentioned electrode arrangement for generating the non-thermal plasma. 
     Moreover, the electrode(s) is/are preferably connected with a high voltage generator, which can be arranged separate from the treating device. 
     The housing of the treating device according to the invention is preferably box-shaped, whereas there are two of the afore mentioned sandwich-like DBD arrangements within the housing above and below the area of treatment. Alternatively, the DBD arrangements can be mounted on opposing sides of the housing so that one DBD arrangement is mounted on the left side of the housing, whereas the other DBD arrangement is mounted on the right side of the housing. 
     Further, the afore-mentioned sandwich-like DBD arrangement preferably comprises an outer electric insulation, which is electrically insulating the outer electrode of the plasma generator. 
     Moreover, there is preferably a gap between the outer electric insulation of the sandwich-like DBD arrangement and the housing, wherein said gap allows a gas flow through the gap. This is advantageous since the plasma generated in the DBD arrangement must reach the area of treatment in the centre of the housing so that there must be a gas flow within the housing. The gas flow within the housing can be generated by natural convection due to the different temperatures within the gas volume. However, it is also possible that the gas circulation within the housing of the treating device is at least partially caused by a pump, which is preferably arranged separate from the treating device. 
     Preferably, the treating device includes a waste gas filter. The waste gas filter is arranged and configured to filter waste gas from within the housing. For example, a ventilator or another suitable means can be provided in order to urge (pull/push) the waste gas from within the housing to the waste gas filter. 
     It should further be mentioned that the plasma generator is preferably arranged within the housing so that the plasma is generated within the housing. Therefore, the treating device according to the invention is different in nature from conventional therapeutic concepts in which the area of treatment and the area of plasma generation are separated from each other. On the contrary, the invention provides that the area of treatment and the area of plasma generation are at least overlapping or even identical. 
     It is well known in the state of the art that plasma generators generally produce ultraviolet (UV) radiation. In some applications this UV radiation contributes to the therapeutic effect of the plasma treatment. However, in other applications, the UV radiation is undesirable. Therefore, the treating device according to the invention preferably comprises a radiation shielding being arranged between the plasma generator and the area of treatment within the housing thereby shielding the treated body part against the UV radiation generated by the plasma generator. 
     However, the afore-mentioned radiation shielding is preferably gas permeable so that the plasma can flow through the radiation shielding and reach the body part which is to be treated. This is important since the plasma treatment requires a physical contact between the non-thermal plasma and the body part which is to be treated. 
     In a preferred embodiment, the radiation shielding comprises several spaced apart UV blocking shielding elements which are preferably curved or angled in such a way that there is no intervisibility between the opposing sides of the radiation shielding while the gas flow between the opposing sides of the radiation shielding is not substantially constricted. 
     The shielding elements are preferably lamellas which are arranged in at least two adjacent layers wherein the lamellas in the adjacent layers are oppositely angled. 
     It should further be mentioned that the radiation shielding and/or the shielding elements (e.g. lamellas) preferably consist of or a coated with an electrically conductive material so that there is not charge build-up on the surface of the shielding elements. The electrically conductive material of the radiation shielding is preferably metal, particularly copper or tin. It should further be mentioned that the radiation shielding and/or the shielding elements are preferably electrically grounded. 
     In the preferred embodiment of the invention, the electrodes, the barrier and the outer insulation of the afore mentioned DBD arrangement are preferably flat or layer-shaped. Further, the electrodes can comprise a wire mesh. 
     Further, the treating device preferably comprises a spacer which is arranged between the area of treatment on the one hand and the plasma generator on the other hand thereby preventing a physical contact between the plasma generator and the body part during treatment. The spacer is preferably substantially flat and/or comprises a wire mesh. In a preferred embodiment, the spacer is configured and arranged to support the object to be treated within the housing. 
     Moreover, it should be noted that the housing of the novel treating device preferably comprises an outer wall consisting of an electrically conductive material which is preferably electrically grounded. 
     The dimensions of the housing are preferably adapted to the size of a hand of a human being so that a patient can introduce his hand through the inlet opening into the housing for sterilizing his hand. Therefore, the inlet opening of the housing preferably comprises a height in the range of 2 cm-20 cm and a width in the range of 5 cm-30 cm. It is preferred that the inlet opening of the housing comprises a width of 10 cm and a height of 4 cm. 
     Further, the housing is preferably sufficiently large for introducing a hand of a human being into the housing so that the entire hand can be sterilized within the housing. Therefore, the housing preferably comprises an inner length in the range of 5 cm-30 cm with a preferred value of the inner length of about 11-12 cm. Further, the housing preferably comprises an inner width in the range of 5 cm-30 cm with a preferred value of the width of about 11-12 cm. Finally, the housing preferably comprises an inner height in the range of 4 cm-20 cm with a preferred value of the inner height of about 7 cm. 
     In another preferred embodiment, the dimensions of the housing are preferably adapted to the size of a forearm including a hand and preferably further including an elbow of a human being so that a patient can introduce his forearm including his hand and preferably further including his elbow through the inlet opening into the housing for sterilizing his forearm including his hand and preferably including his elbow. Further, the housing is preferably sufficiently large for introducing a forearm including a hand and preferably further including an elbow of a human being into the housing so that the entire forearm including the hand and preferably further including the elbow can be sterilized within the housing. 
     In another preferred embodiment, the dimensions of the housing are preferably adapted to the size of a foot of a human being. 
     It should further be noted that the non-thermal plasma according to the invention preferably comprises a gas temperature (i.e. the temperature of the atoms and molecules) below +40° C., when measured on the treated surface. 
     Further, the treating device can include an on/off-switch for switching the integrated plasma generator on and off. 
     Moreover, there can be a light barrier which detects whether an object of treatment (e.g. a hand) is inserted through the inlet opening into the housing. The light barrier can be coupled with the plasma generator so that the plasma generator is switched off if no object is introduced through the inlet opening, whereas the plasma generator is switched on if an object of treatment is present within the housing. 
     In a preferred embodiment, the treating device is configured to provide an after glow within the housing for treating the object with the non-thermal plasma, particularly for the in-vivo sterilization of a hand or a forearm including a hand and preferably including an elbow of a human being. Within the phase of after glow, the plasma generator does not produce plasma. However, plasma within the housing is effective for treating an object, particularly for the in-vivo sterilization. On the one hand, the use of the after glow can decrease the energy consumption of the treating device. On the other hand, the use of the after glow can increase the usage safety of the treating device since no object, in particular no part of a human being or other sensible objects/devices, is introduced within the housing when the plasma is generated (power on). 
     For example, the plasma generator can be switched on and after, for example, 2 sec. switched off. The plasma generated within the 2 sec. remains effective within the housing for a certain time span after switching off for treating an object, particularly for the in-vivo sterilization. 
     Preferably, the treating device includes indicating means for indicating the beginning and the end of the after glow. 
     Preferably, the treating device can include an opening/closing means for closing the inlet opening during plasma generating and opening the inlet opening after plasma generating. In one embodiment, the opening/closing means is closed and locked during plasma generating and opens only when the plasma generator does not generates plasma. 
     Further, it is possible to provide a plasma ionization degree sensor for detecting the ionization degree of the plasma within the housing. 
     Preferably, the plasma generator, the indicating means and/or the opening/closing means are controlled based on one or more predetermined time spans. 
     However, it is also possible to control the plasma generator, the indicating means and/or the opening/closing means based on the ionization degree of the plasma within the housing detected by the plasma ionization degree sensor. 
     The invention and its particular features and advantages will become apparent from the following detailed description considered with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of a preferred embodiment of a treating device according to the invention. 
         FIG. 2  shows another perspective view of the treating device according to  FIG. 1 . 
         FIG. 3  shows a cross sectional view of the treating device shown in  FIGS. 1 and 2 . 
         FIG. 4  shows a schematic view of a plasma generator using dielectric barrier discharge. 
         FIG. 5  shows a cross sectional view of the radiation shielding shown in  FIG. 4 . 
         FIG. 6  shows a cross sectional view similar to  FIG. 3  but also showing the design of the radiation shielding. 
         FIG. 7A  shows a perspective view of a side plate of the housing of the treating device. 
         FIG. 7B  shows a perspective view of the isolator of the DBD arrangement. 
         FIG. 7C  shows a perspective view of the front plate of the treating device with an inlet opening. 
         FIG. 7D  shows a perspective view of an intermediate plate of the treating device. 
         FIG. 7E  shows a perspective view of a rear plate of the treating device comprising an opening for cables. 
         FIG. 7F  shows a perspective view of an upper and lower plate of the housing. 
         FIG. 7G  shows an exemplary embodiment of the electrodes of the afore mentioned DBD arrangement. 
         FIG. 8  shows another embodiment of an electrode arrangement which can be used for plasma generation instead of the DBD arrangement. 
         FIG. 9A  shows a perspective view of a preferred embodiment of a DBD electrode arrangement comprising a plate as a first electrode and a wire-mesh as a second electrode. 
         FIG. 9B  shows a sectional view of the electrode arrangement according to  FIG. 9A . 
         FIG. 10  shows a perspective view of an electrode arrangement comprising two wire-meshs. 
         FIG. 11  shows a perspective view of a junction of the wires of several wire-meshs. 
         FIG. 12  shows a perspective view of a junction of two insulated wires. 
         FIG. 13  shows a modification of the electrode arrangement according to  FIG. 10  additionally comprising a cover. 
         FIG. 14  shows a cross-sectional view of a sandwich-like DBD electrode arrangement comprising three electrodes. 
         FIG. 15  shows a sectional view of a modification of the embodiment according to  FIGS. 9A and 9B , wherein a wire-mesh is embedded into the dielectric barrier. 
         FIGS. 16A and 16B  are schematic views illustrating different uses of an after glow. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The drawings illustrate a preferred embodiment of a treating device  1  for the in-vivo sterilization of a hand or a forearm including a hand and preferably further including an elbow of a human being by means of a non-thermal plasma. 
     The treating device  1  comprises a box-shaped housing  2  with an inlet opening  3  at the front side of the housing  2  wherein the dimensions of the inlet opening  3  are adapted to the size of a hand of a human being so that a patient can introduce his hand through the inlet opening  3  into the housing  2  of the treating device  1 . Further, the dimensions of the entire housing  2  are adapted to the size of a hand of a human being so that the entire hand can be placed within the housing  2  for a plasma treatment. In this embodiment, the housing  2  comprises a length of 11.5 cm, a width of 11.4 cm and a height of 7 cm. Further, the inlet opening  3  comprises a width of 10 cm and a height of 4 cm. 
     Further, the treating device  1  comprises an opening  4  at its rear surface opposite the inlet opening  3  while the opening  4  serves for accommodating cables or the like. However, the rear opening  4  is covered by an insulator  5  consisting of polytetraflouroethylene. 
     Further, the treating device  1  comprises an integrated plasma generator which generates a non-thermal plasma for the in-vivo sterilization. 
     The plasma generator comprises two substantially flat dielectric barrier discharge (DBD) arrangements  6 ,  7 . The DBD arrangement  6  is arranged within the housing  2  above the area of treatment as shown in  FIG. 3 , while the DBD arrangement  7  is arranged within the housing  2  below the area of treatment. 
     The design of the DBD arrangements  6 ,  7  is schematically shown in  FIG. 4 . Each of the DBD arrangements  6 ,  7  comprises a barrier  8  sandwiched between two electrodes  9 ,  10  which are adhered to the top and bottom sides of the barrier  8  which consists of polytetraflouroethylene. 
     Further, the DBD arrangement  6  comprises an outer insulator  11  and a radiation shielding  12  facing to the area of treatment within the housing  2  so that the radiation shielding  12  prevents that the hand of the patient within the housing  2  is affected by any ultraviolet radiation generated by the DBD arrangements  6 ,  7 . 
       FIG. 5  shows a cross sectional view of the radiation shielding  12  along line A-A in  FIG. 4 . The radiation shielding  12  comprises two adjacent layers  13 ,  14  of parallel metallic lamellas  15 ,  16 . The lamellas  15  in the upper layer  13  of the radiation shielding  12  are oppositionally angled with regard to the lamellas  16  in the lower layer  14  of the radiation shielding  12 . Therefore, there is no intervisibility between the opposing sides of the radiation shielding  12  so that no ultraviolet radiation is transmitted through the radiation shielding  12 . In other words, the radiation shielding  12  blocks any ultraviolet radiation generated by the DBD arrangements  6 ,  7 . 
     Further, the treating device  1  comprises two spacers  17 ,  18  for the DBD arrangements  6 ,  7 , wherein the spacers  17 ,  18  avoid a physical contact between the hand and the DBD arrangements  6 ,  8 . In this embodiment, the spacers  17 ,  18  each consist of a wire mesh. 
       FIGS. 7A-7G  show different views of the parts of the afore mentioned treating device while the views are self explanatory so that no further explanation is necessary. 
       FIG. 8  shows another embodiment of an electrode arrangement which can be used instead of the afore-mentioned DBD arrangements  6 ,  7 . 
     The electrode arrangement comprises a copper plate  19 , a teflon plate  20  and a wire mesh  21  made of an electrically conductive material. The copper plate  19  and the wire-mesh  21  are adhered to opposing sides of the teflon plate  20 . 
     Further, the wire mesh  21  is electrically grounded, whereas the copper plate  19  is connected with a high voltage source generating a high-voltage of U=18 kV pp  and a frequency of f=12.5 kHz. 
       FIGS. 9A and 9B  show another preferred embodiment of a DBD electrode arrangement  1 A for generating a non-thermal plasma. The electrode arrangement  1 A comprises a plate-shaped electrode  2 A made of an electrically conductive material, e.g. copper or aluminium. The plate-shaped electrode  2 A has a thickness in the range of 0.5-1 mm. 
     Further, the electrode arrangement  1 A comprises a dielectric barrier  3 A made of polytetrafluoroethylene, wherein the material of the dielectric barrier  3 A is applied to the lower surface of the plate-shaped electrode  2 A. 
     Moreover, the electrode arrangement  1 A comprises a further electrode  4 A formed by a wire-mesh which is adhered to the dielectric barrier  3 A on the side opposite the electrode  2 A. 
     The electrode  4 A is electrically grounded while the other electrode  2 A is electrically connected to a high voltage generator  5 A which is applying an alternating current signal to the electrode  2 A with a frequency of f=12.5 kHz and a peak-to-peak-voltage of HV=18 kV pp . Therefore, the high voltage generator  5 A triggers a dielectric discharge wherein the plasma is generated in the meshes of the mesh-shaped electrode  4 A. 
       FIG. 10  shows another embodiment of a two-dimensional electrode arrangement  11 A similar to the electrode arrangement  1 A shown in  FIGS. 9A and 9B . 
     However, the electrode arrangement  11 A comprises two mesh-shaped electrodes  12 A,  13 A, wherein the individual wires of at least one of the electrodes  12 A,  13 A are surrounded by a cladding made of an electrically insulating and dielectric material forming a dielectric barrier between the electrodes  11 A,  12 A. 
     The electrode  13 A is electrically grounded while the other electrode  12 A is connected to a high-voltage generator  14 A triggering a dielectric barrier discharge in the electrode arrangement  11 A wherein the plasma is generated in the meshes of the electrodes  12 A,  13 A. 
     It should further be noted that the electrode arrangement  11 A is flexible so that the shape of the electrode arrangement  11 A can be adapted to any desired shape. 
       FIG. 11  shows a junction between individual wires  15 A,  16 A,  17 A of adjacent mesh-shaped electrodes. In this embodiment, the wire  16 A is surrounded by a cladding  18 A made of an electrically insulating and dielectric material thereby forming the dielectric barrier. The other wires  15 A,  17 A are not insulated. 
       FIG. 12  shows another embodiment of a junction of wires  19 A,  20 A of adjacent mesh-shaped electrodes. In this embodiment both the wire  19 A and the wire  20 A is surrounded by a cladding  21 A,  22 A made of an electrically insulating and dielectric material. 
       FIG. 13  shows a modification of the electrode arrangement shown in  FIG. 10  so that reference is made to the above description relating to  FIG. 10 . 
     One characteristic feature of this embodiment is that the electrode arrangement  11 A additionally comprises a cover  23 A. The cover can have different purposes, e.g. increasing the local density of reactive species, reducing the time for sterilization, filtering out unused reactive species, effecting a better control over the plasma or operating under reduced pressure. 
       FIG. 14  shows another embodiment of an electrode arrangement  28 A suitable for generating a non-thermal plasma. The electrode arrangement  28 A comprises a centre electrode  29 A formed by a massive plate made of copper. 
     Further, the electrode arrangement  28 A comprises two flat dielectric barriers  30 A,  31 A each consisting of a flat plate made of polytetrafluoroethylene, wherein the dielectric barriers  30 A,  31 A are attached to opposing sides of the centre electrode  29 A. 
     Further, the electrode arrangement  28 A comprises two mesh-shaped outer electrodes  32 A,  33 A which are attached to the outer sides of the dielectric barriers  30 A,  31 A. 
       FIG. 15  shows a modification of the electrode arrangement shown in  FIGS. 9A and 9B  so that reference is made to the above description relating to  FIGS. 9A and 9B . Further, the same reference numerals are used for corresponding parts and details. 
     One characteristic feature of the electrode arrangement  1 A according to  FIG. 15  is that the electrode  4 A is embedded into the dielectric barrier  3 A. There is a distance d 1 =1 mm between the wire-mesh of the electrode  4 A and the lower surface of the electrode  2 A. Further, there is a distance d 2 =0.1 mm between the wire-mesh of the electrode  4 A and the outer surface of the dielectric barrier  3 A. It is essential that the distance d 1  is greater than the distance d 2 . However, if it is desired to have a discharge on one side only, the embedded electrode  4 A must be embedded more deeply than the distance d 1  between the electrodes  2 A,  4 A. 
     If a flexible electrode arrangement  1 A is desired, both electrodes  2 A,  4 A are made of a flexible wire-mesh or parallel wires having a distance of approximately 1 cm, wherein the dielectric barrier  3 A can be made of a flexible material, e.g. silicone rubber. 
     The outer electrodes  32 A,  33 A are electrically grounded while the centre electrode  29 A is electrically connected to a high-voltage generator. 
       FIGS. 16A and 16B  are schematic views describing different uses of an after glow. 
     In  FIG. 16A , the plasma generator is switched on at time t 1  and preferably automatically switched off after a predetermined time at time t 2 . Thus, the plasma generator generates plasma within time t 1  and time t 2 . Although the plasma generator is switched off between time t 2  (beginning of the after glow) and time t 3  (end of after glow), the plasma generated between time t 1  and time t 2  and contained within the housing  2  is effective for treating an object, particularly for the in-vivo sterilization for a hand and/or a forearm of a human being. The time span between time t 2  and time t 3  can thus be referred to as after glow. 
     After time t 3 , the plasma within the housing is no longer effective for treating an object, particularly not effective for the in-vivo sterilization. 
     The treating device can include an indicating means, for example acoustic and/or visual means, for example one or more lamps for indicating particularly times t 1 , t 2  and t 3 . For example, one lamp can light yellow between time t 1  and time t 2  indicating that an object should or must not be introduced into the housing. Another lamp can light green between time t 2  and time t 3  indicating that the treating device is ready for treating/sterilizing. Still another lamp can light red after time t 3  indicating that the plasma within the housing is no longer effective for treating/sterilizing. 
     The treating device can further include an opening/closing means arranged and configured to close the inlet opening  3  when the plasma generator generates plasma (e.g. between time t 1  and time t 2 ) for preventing an object, for example a hand, to be introduced into the housing and to open the inlet opening  3  when the plasma generator does not produce plasma (e.g. during time t 2  and time t 3 ). Although the device is safe even when the plasma is generated (due to the grounded electrode configuration), the use of the after glow may further increase usage safety. For example, the use of the after glow can have advantages in particular with regard to wet objects and metallic objects (e.g. rings, watches, bracelets). 
     It is also possible to provide a plasma ionization degree sensor for detecting the plasma effectiveness/ionization degree within the housing  2  and to control the plasma generator, the opening/closing means and/or the indicating means in response to the values detected by the plasma ionization degree sensor. However, it is also possible to control the plasma generator, the indicating means and/or the opening/closing means by one or more predetermined time spans. The one or more time spans can be preset by the manufacturer of the treating device and/or individually definable by a user, for example a physician or a nurse. 
     It is further possible to maintain the treating device in a “stand by mode” as schematically shown in  FIG. 16B . In  FIG. 16B , the plasma generator is initially switched on at time t. The plasma generator is automatically switched off at time t″, automatically switched on at time t′, automatically switched off at time t″ and so on. Thus, after initially switching on the treating device (for example in the morning and switched off in the evening), the plasma effectiveness/ionization degree within the housing  2  is kept at a sufficient (predetermined) degree for treating/sterilizing. With other words, the treating device is after switching on permanently effective for treating an object, particularly for the in-vivo sterilization. The embodiment shown in  FIG. 16B  can be used with the indicating means, the opening/closing means and/or the plasma ionization degree sensor according to  FIG. 16A . 
     Although the invention has been described with reference to the particular arrangement of parts, features and the like, these are not intended to exhaust all possible arrangements of features, and indeed many other modifications and variations will be ascertainable to those of skill in the art.