WO2019238870A1

WO2019238870A1 - Method for inspecting and/or monitoring an electrode arrangement for producing a non-thermal plasma

Info

Publication number: WO2019238870A1
Application number: PCT/EP2019/065582
Authority: WO
Inventors: Julia Zimmermann; Sylvia CANTZLER; Maximilian CANTZLER; Hannes WEILEMANN; Gregor Morfill
Original assignee: Terraplasma Gmbh
Priority date: 2018-06-15
Filing date: 2019-06-13
Publication date: 2019-12-19
Also published as: DE102018209729A1; EP3806912A1

Abstract

The invention relates to a method for inspecting and/or monitoring an electrode arrangement (1) for producing a non-thermal plasma, comprising the following steps: determining at least one plasma performance from the performance parameters characterising the electrode arrangement (1); a) temporally detecting the at least one performance parameter; and/or b) comparing the at least one performance parameter with at least one pre-determined nominal parameter value, and obtaining a comparison result; evaluating a function or operability of the electrode arrangement (1) on the basis of the comparison result, and preferably selecting at least one action according to the comparison result.

Description

DESCRIPTION

Method for testing and / or monitoring an electrode arrangement for generating a non-thermal plasma

The invention relates to a method for testing and / or monitoring an electrode arrangement for generating a non-thermal plasma.

Non-thermal plasmas are used in a variety of applications to reduce a number of pathogenic germs or to eliminate such germs, for example in the field of wound treatment, the treatment of skin diseases, food hygiene, the production of water for intravenous injection, drinking water treatment, decontamination , Disinfection or sterilization of objects, in particular medical devices and / or in the military, in the civilian area, in the aerospace sector, in particular surface treatment, very particularly surface sterilization or disinfection, inactivation of allergens, the Seed treatment, plant protection, odor reduction, for example when refreshing textiles or textile products, in particular clothing or mattresses, air purification and monitoring, and many other things. Non-thermal plasmas are also used to treat wounds and treat skin diseases because, in addition to their germ-reducing effects, they also have healing effects. Many of these applications are critical in the sense that for the user himself or for the person to whom or for whom the application is carried out, for example a patient or a consumer of drinking water treated in this way, a user of seeds or the like, there are significant risks can, if the non-thermal plasma is not generated or applied to a sufficient extent, in particular not with a sufficient dose of plasma, during use. A limitation of a maximum dose of certain species may also have to be observed for safety reasons. With flat or geometrically linear plasma generation, it is also important to obtain information about whether the plasma is generated evenly along an area or line on which it is to be generated, since otherwise there is a risk that that certain areas or line areas are treated to a reduced extent or not at all, while other areas may be exposed to an excessive amount of plasma.

There is therefore a need for a method with which it can be reliably determined whether an electrode arrangement for generating a non-thermal plasma has a function as intended, and / or with which this function as intended or generally the operation during the application can be continuously monitored ,

The invention has for its object to provide a method for testing and / or monitoring an electrode arrangement for generating a non-thermal plasma, which contributes to avoiding the disadvantages mentioned, which should in particular make it possible to adapt the electrode arrangement to an intended function or Checking and / or monitoring functionality and, if necessary, automatically executing suitable measures (such as stopping the treatment or carrying it out up to a predetermined target plasma dose).

The object is achieved by creating the subject matter of claim 1. Advantageous configurations result from the subclaims.

The object is achieved in particular by creating a method for testing and / or monitoring an electrode arrangement for generating a non-thermal plasma, which has the following steps: at least one power parameter is determined which is characteristic of a plasma power of the electrode arrangement is. The performance parameter is determined in particular when the electrode arrangement is in operation; it is particularly characteristic of an instantaneous plasma power of the electrode arrangement during its operation.

The at least one performance parameter is preferably recorded over time, in particular as a function of time.

As an alternative or in addition, the at least one specific performance parameter is compared with at least one predetermined target parameter value, and it becomes this Comparison received a comparison result. A function or functionality of the electrode arrangement is assessed on the basis of the comparison result.

With the aid of the method proposed here, it is possible, both when the electrode arrangement is started up and during operation, to determine its function or functionality reliably and precisely, and thus in particular risks for a user associated with inadequate, reduced or non-existent functionality of the electrode arrangement to avoid the electrode arrangement or for third parties.

Depending on the comparison result, at least one action is preferably selected. In this way it is possible to react to the comparison result and thus also to the function or functionality of the electrode arrangement and to select an action adapted to it. The action can also be selected as a function of the time-measured performance parameter or a value derived therefrom, for example depending on a plasma dose determined on the basis of the time performance measurement parameter.

The fact that the performance parameter is recorded over time means, in particular, that it is determined continuously, continuously or at specific time intervals or at a specific sampling rate, in particular measured or derived from a measurement of another variable. It is possible that the time-recorded values of the performance parameter are saved.

A dose size, in particular a plasma dose, is preferably derived from the at least one time-measured performance parameter. For this purpose, the at least one performance parameter or a plasma performance derived therefrom can, in particular, be summed up over time or integrated in time. It is thus possible at any time during the operation of the electrode arrangement to determine a currently delivered, that is to say in particular applied, plasma dose.

The at least one action can be selected in particular as a function of the dose size, in particular the plasma dose. In particular, operation of the electrode arrangement can be ended when a predetermined value for the plasma dose and thus preferably a desired treatment result has been reached. A non-thermal plasma is understood in particular to be a plasma in which a temperature describing the distribution of the kinetic energy of electrons of the plasma, which is also referred to as the electron temperature, is not identical and in particular is very much higher than the distribution of the kinetic Energy describing the temperature of the ions comprised by the plasma, in particular atomic ions and / or molecular ions, which is also referred to as the ion temperature. The electron temperature is much higher than the ion temperature, and the ion temperature can be selected in particular in the range from 25 ° C. to at most 100 ° C. Such a plasma is also referred to as cold plasma due to the comparatively low ion temperature.

A plasma is a state of matter in which charged particles with positive and negative charges are in gas phase next to each other, with a neutral electrical charge for the volume in question averaged over a certain volume. The plasma also preferably comprises non-charged atoms and / or molecules which are in electronically, vibrationally and / or rotationally excited states and which are also referred to as excited particles, and / or free radicals, in particular thus not charged reactive atoms and / or molecules, which are also referred to as reactive particles or reactive species.

An electrode arrangement here means in particular an arrangement of electrically conductive electrodes relative to one another, which is set up to generate a non-thermal plasma when a voltage, in particular an AC voltage, is applied to the electrode arrangement. A plasma source having the electrode arrangement also preferably has means for supplying the electrodes with electrical power, in particular a voltage source, and preferably a control device for influencing, specifying, measuring, evaluating, controlling and / or regulating the current quantities applied to the electrodes, and consequently in particular a voltage and / or a current.

The electrode arrangement preferably has a first electrode and a second electrode, which are spaced apart from one another by a dielectric, so that plasma discharges, in particular surface micro-discharges, can be generated on one of the two electrodes when a voltage, in particular an AC voltage, is applied to the electrodes. The electrode arrangement is thus set up in order to generate a non-thermal plasma independently of a surface external to the electrode arrangement. In particular, the electrode arrangement is in the form of an SMD electrode arrangement (surface micro Discharge) trained. In particular, there is no need for a surface to be treated, which is connected as a counter electrode. The two electrodes of the electrode arrangement are preferably in physical contact with the dielectric, whereby they can be embedded in the dielectric or can be arranged on the dielectric, for example by vapor deposition, screen printing, physical or chemical vapor deposition, by laying on or pressing on, sticking on, or in another suitable way, in which case they are arranged tightly and in particular without an air gap on the dielectric. Thus, in particular both electrodes of the electrode arrangement are arranged on a common side of a surface to be treated. In particular, the surface to be treated is not arranged between the two electrodes of the electrode arrangement.

The electrode arrangement is in particular set up to generate a non-thermal plasma in air, in particular in ambient air. No special gas is therefore preferably used to generate the non-thermal plasma, in particular no such special gas, in particular no carrier gas, is fed to the electrode arrangement.

The method proposed here is particularly suitable for testing and / or monitoring such an electrode arrangement. In particular with such an electrode arrangement, the plasma power is also directly dependent on an area or line along or on which the plasma is generated, any irregularities in the plasma generation and / or area parts and / or line areas, on or in which, for example, due to If no plasma is generated from contaminants, directly reduce the plasma output. The comparison of the power parameter with the at least one predetermined target parameter value can thus also be used to determine whether the plasma is generated uniformly.

A plasma power of the electrode arrangement is understood to mean that part of the electrical power absorbed by the electrode arrangement that is used directly to generate the non-thermal plasma and in particular is directly related to a generation rate for reactive particles comprised by the plasma. If a parameter is recorded as the power parameter that is characteristic of this plasma power, the function or functionality of the electrode arrangement can be concluded in a particularly safe and reliable manner, because in this case the power parameter provides direct information about the plasma generation through the electrode arrangement there. An assessment of the function or functionality of the electrode arrangement is understood in particular to mean that a statement about the function or functionality of the electrode arrangement is derived, be it indirectly by selecting a specific action and / or directly by outputting a message describing or identifying the functionality of the electrode arrangement. The functionality can be assessed in the sense of a simple, binary determination as to whether the electrode arrangement is functional or not, but it is also possible for the functionality or functionality of the electrode arrangement to be assessed in a more complex manner, in particular with a view to determining the current one Plasma power and, if applicable, the selection of an action depending on the current plasma power determined.

In the context of the method, the plasma power is preferably recorded as a power parameter or on the basis of the at least one power parameter.

According to a development of the invention, it is provided that the action is selected from a group consisting of an output of an "in order" signal, an output of a "need for action" signal, an output of a "not in order" Signal, a communication of the - in particular instantaneous - plasma power and / or a - in particular instantaneous - plasma dose to an operator of the electrode arrangement, an adjustment of an operating time or treatment time to the comparison result, an end of operation of the electrode arrangement, and a continuation of the Operation of the electrode arrangement without any further measure, in particular without outputting a signal or a message. An "in order" signal is also referred to as a green signal, a "need for action" signal is also referred to below as a yellow alarm, and a "not in order" signal is also referred to below as a red alarm designated. A green signal indicates that the electrode arrangement is working as intended.

Preferably, the at least one performance parameter, a value derived therefrom, such as the plasma dose, the at least one selected action and / or its result, in particular at least one signal and / or at least one message, is given to a user, user or operator the electrode arrangement communicates via the Internet and / or wirelessly, in particular via WLAN or Bluetooth, preferably to a smartphone app. It is preferably also provided that the plasma power is additionally communicated, in particular instantaneously, if necessary also as a time series over a certain number of previous time units, in particular seconds or minutes. The green signal can in particular be output if the at least one power parameter deviates from the predetermined target parameter value by less than a first predetermined limit value, for example by less than 15%. A yellow alarm informs an operator of the electrode arrangement that the electrode arrangement should be checked, whereby further steps, for example cleaning the electrode arrangement, cleaning contacts, or other such measures, may be necessary. Such a yellow alarm is preferably output when the deviation of the at least one power parameter from the at least one predetermined target parameter value is greater than the first predetermined limit value, it being less than a second predetermined limit value, the second predetermined limit value being greater is than the first predetermined limit. The second predetermined limit value can correspond, for example, to a deviation of 30% from the predetermined target parameter value. The yellow alarm can also be output when the deviation of the at least one performance parameter from the at least one predetermined target parameter value is equal to the first predetermined limit value. A red alarm can be issued in particular if it is no longer sensible to continue operating the electrode arrangement due to a lack of functionality or either for the electrode arrangement itself, for the later user of a good treated with the plasma (e.g. in drinking water treatment), the operator, or for a person treated with the electrode arrangement is dangerous. The red alarm can be output in particular if the at least one performance parameter deviates from the at least one predetermined target parameter value by the second predetermined limit value or by more than the second predetermined limit value.

According to one embodiment of the method, the at least one predetermined target parameter value can be a target value, in which case the performance parameter is compared with the — in particular exactly one — target value and the function or functionality of the electrode arrangement is assessed on the basis of the comparison result. In particular, a deviation from the target value both upwards and downwards, at least when certain limit values defined relative to the target value are exceeded, is an indication of a lack of function or functionality of the electrode arrangement.

According to another embodiment of the method, it is possible for the at least one predetermined target parameter value to be a minimum value. In this case, the performance Parameter compared with the minimum value in such a way that it is checked whether the performance parameter is greater or less than the minimum value. The electrode arrangement is functional if the performance parameter is greater than or equal to the minimum value, the electrode arrangement not functioning if the performance parameter is less than the minimum value. A range can also be defined for a yellow alarm, which then extends from the minimum value to a predetermined limit value that is smaller than the minimum value by a predetermined amount or a predetermined factor. The range for the red alarm then extends from the predetermined limit value to smaller values, the range for the yellow alarm being arranged between the predetermined limit value and the minimum value. In this case, the range for the green signal is above the minimum value.

In a corresponding - only reverse - manner, the setpoint parameter value can be defined as the maximum value in a further embodiment of the method. The electrode arrangement is not functional if the performance parameter takes values above the maximum value, the electrode arrangement is functional if the performance parameter takes values below or up to the maximum value. The range of the green signal then extends from smaller values, in particular from zero up to the maximum value, the range of the yellow alarm extending from the maximum value to a predetermined limit value, which by a predetermined amount or a predetermined factor is greater than the predetermined limit. The range of the red alarm then extends from the predetermined limit value to higher values.

In a further embodiment of the method, it is possible to provide two predetermined target parameter values with which the at least one performance parameter is compared. The two predetermined target parameter values define a range of values or limits of a range of values, the electrode arrangement being assessed as functional within this range of values or range of values. In particular, a first predetermined target parameter value is defined as the minimum value of the value band or value range, with a second, larger target parameter value being defined as the maximum value of the value band or value range. The areas for the yellow alarm are then each assigned to the maximum value on the one hand and the minimum value on the other hand in the sense as was explained above for the minimum value and the maximum value. Alternatively, it is also possible that an area for a yellow alarm does not - as explained above - extend from the predetermined target parameter value in the direction of the area for the red alarm, but rather that it extends into the area of the green alarm. Signal extends. In this case, for example, the predetermined limit value assigned to the minimum value can be greater than the minimum value, and the predetermined limit value assigned to the maximum value can be smaller than the maximum value. Alternatively, it is also possible to define a yellow alarm area so that it includes the predetermined target parameter value, preferably comprises it symmetrically.

The at least one predetermined target parameter value is preferably selected as a function of a desired operating mode of the electrode arrangement, in particular as a function of a desired plasma chemistry, in particular a desired concentration of certain active species in the plasma. For example, it is possible for various desired parameter values, in particular a permissible value range or a permissible value band, to be specified, on the one hand, in the event that the non-thermal plasma generated is intended to essentially comprise oxygen species, for example ozone (oxygen mode), or that the non-thermal plasma should essentially comprise nitrogen species, in particular nitrogen oxides (nitrogen mode). It is also possible to choose an intermediate range between these operating modes. The plasma chemistry strongly depends on the selected plasma power and can thus be predetermined by this. In this respect, the function or functionality of the electrode arrangement must also be examined with a view to the plasma power as a function of the selected operating mode.

The compliance with a desired operating mode (in particular oxygen mode, nitrogen mode, or an intermediate area) is preferably also monitored as part of the method.

The signals described here can be output, for example, as light signals. In particular, it is possible for the green signal to be output as a green light, the yellow alarm as a yellow light, and the red alarm as a red light. In particular, light emitting diodes can be used to output the light signals.

Alternatively or additionally, the signals and / or messages can also be output in text form, in particular in a display, as acoustic signals or messages, by vibration, or in another suitable manner. A notification of the current plasma power and / or the currently applied plasma dose to the operator enables the operator to estimate a treatment result of the electrode arrangement for a specific treatment duration and, if necessary, the treatment duration to the current plasma power and / or plasma Adjust dose. If, for example, the electrode arrangement has an instantaneous plasma power that is reduced compared to a nominal plasma power, the duration of treatment by the operator can be extended in a suitable manner in order to apply a predetermined target plasma dose. Such an adjustment of the treatment duration can, however, preferably also take place automatically, in particular as a function of the comparison result. It is also possible for the plasma dose to be monitored as part of the method, it being possible for the duration of treatment, in particular the operation of the electrode arrangement, to be ended automatically as part of the method when a predetermined target plasma dose has been reached. The operator is preferably informed of the automatically changed treatment time, or the operator is required to operate the electrode arrangement until it ends the operation independently, in which case the changed treatment time is taken into account virtually automatically. The treatment time preferably corresponds to an operating time of the electrode arrangement, since this is preferably only operated during a treatment that is actually carried out. Treatment then begins in particular with the commissioning of the electrode arrangement and ends with the termination of the operation of the electrode arrangement. The applied plasma dose can be automatically communicated to the user and / or logged after the treatment.

The method proposed here is particularly preferably carried out by recording / monitoring the plasma dose applied by the electrode arrangement, which is also referred to as plasma monitoring. The plasma dose delivered during the operation of the electrode arrangement, in particular during a treatment period, is recorded on the basis of the at least one power parameter. A message or a signal can then be output when a predetermined target plasma dose has been applied, or the treatment can be ended automatically in this case. A safety surcharge on the predetermined target plasma dose can also be taken into account as long as no safety-relevant application time window is exceeded. The plasma dose can in particular be determined as a product or preferably an integral of the (instantaneous) plasma power, which is determined as a power parameter or on the basis of the power parameter, with / over time, in particular the duration of treatment.

The operation of the electrode arrangement can in particular be terminated or blocked if it is no longer sensible to continue operating it or if it is dangerous for the electrode arrangement itself, for the operator or for a person treated with the electrode arrangement. In particular, the operation of the electrode arrangement can be ended or blocked simultaneously with the output of a red alarm.

If an unimpaired functionality of the electrode arrangement is determined, its further operation is preferably permitted or continued. In particular, allowing or continuing operation of the electrode arrangement can take place simultaneously with the output of a green signal, in particular if the testing and / or monitoring method is carried out when the electrode arrangement is started up. If the testing and / or monitoring method is carried out while the electrode arrangement is in operation, the operation is preferably continued when an undiminished functionality is ascertained, without further measures being carried out, in particular without output of signals.

According to a development of the invention, it is provided that the method is carried out immediately after the electrode arrangement has been started up. In particular, it is possible for the method to be carried out immediately after each start-up of the electrode arrangement — always new, preferably automatically. In this way, the electrode arrangement can be checked directly during start-up, with the operator of the electrode arrangement preferably being given feedback as to whether the electrode arrangement is functional. In this way, it can always be determined before the actual use of the electrode arrangement, in particular before treating a surface, a liquid, a bulk material, or a person with the electrode arrangement, whether the electrode arrangement is functional, the actual use of the electrode arrangement possibly not taking place and rather it is checked, cleaned or sent for repair. On the one hand, this has the advantage that the operator is informed of problems in the electrode arrangement at an early stage, so that incorrect treatment or treatment which may not take place unnoticed is avoided, and measures can be taken directly to maintain the functionality of the electrode arrangement or sure. For treatment protocols that may need to be prepared, it is advantageous if it can be noted immediately when the electrode arrangement is put into operation whether or that it is functional.

Alternatively or additionally, it is possible for the method to be carried out repeatedly, in particular periodically, at predetermined operating times, stochastically or event-controlled, or continuously during operation of the electrode arrangement (monitoring). Operation of the electrode arrangement here means in particular the actual use thereof, for example for treating a surface, a person, for water treatment, for food preparation, for disinfecting objects, for seed treatment, for crop protection, for odor reduction, for refreshing clothing or mattresses , and much more. In this way it can be ensured that the electrode arrangement is monitored during its operation, so that a fault or a reduced functionality of the electrode arrangement can be determined promptly. This increases the safety of the operation of the electrode arrangement and in particular the success of its use, and thus reduces the risks associated with inadequate operation of the electrode arrangement or its failure.

According to one embodiment of the method, the at least one power parameter is recorded exclusively during use of the electrode arrangement. In particular, according to one embodiment, the method is carried out exclusively during use of the electrode arrangement. In this way, it can in particular be ensured that only a plasma dose that is actually used as intended is detected.

The method can be initialized in an event-controlled manner, for example by an external request, in particular by a manual request from an operator. However, the method is particularly preferably started automatically, in particular at regular intervals or at predetermined operating times.

A continuous or permanent implementation of the method during the operation of the electrode arrangement is particularly advantageous if the plasma dose emitted by the electrode arrangement is to be determined or monitored. In particular, such a configuration enables the electrode arrangement to be stopped automatically and thus a treatment duration after a predetermined target plasma dose has been reached. in particular depending on a desired type of treatment or a desired treatment success.

The currently reached plasma dose, the achieved plasma dose after the end of the treatment period and / or the at least one performance parameter are / are preferably given to a user via the Internet and / or a preferably wireless connection to a mobile device, in particular to a smartphone -App, communicated. The user can preferably not only check / monitor the operation of the electrode arrangement, but also influence or control it via such a mobile device, in particular via the smartphone app.

Monitoring the electrode arrangement is also advantageous with regard to variability / scatter in production, in particular series production. Such effects can then be easily compensated for by means of the test / monitoring method proposed here by suitably adapting the treatment duration with a view to the predetermined target plasma dose.

According to a development of the invention, it is provided that the at least one predetermined target parameter value is constantly predetermined. This can be the case in particular if external conditions under which the electrode arrangement is checked and / or monitored are always at least approximately identical and / or if the at least one predetermined target parameter value is sufficiently insensitive to varying external conditions. In this respect, a power parameter is preferably used that varies at most to a small extent with external conditions of the electrode arrangement. The power parameter is particularly preferably selected such that its relationship to the actual plasma power of the electrode arrangement depends only to a small extent, preferably not, on such external conditions, in particular a temperature, air humidity, aging effects such as corrosion, oxidation, deposits and the like. In this way it can be ensured that the power parameter in any case only depends on the plasma power of the electrode arrangement and is therefore always characteristic only of the plasma power of the electrode arrangement.

Alternatively, it is possible for the at least one predetermined target parameter value to be stored as a function of at least one application parameter of the electrode arrangement, it being possible in particular to call up or activate it as a function of the at least one application parameter. The at least one predetermined target parameter value is preferably in Dependence on the at least one application parameter is stored in a map from which it can be read depending on the at least one application parameter. This is particularly useful for checking and / or monitoring the electrode arrangement during its operation, in particular if the conditions of use of the electrode arrangement and thus a value of the at least one application parameter can change over time. The at least one application parameter is preferably selected from a group consisting of an ambient temperature of the electrode arrangement and a relative air humidity in an environment of the electrode arrangement. This is particularly relevant for the treatment of damp surfaces or damp or wet environments, for example for wound treatment or water treatment. It may be sufficient to store two different values for the at least one predetermined target parameter value as a function of the relative air humidity, for example a first value for a relative air humidity of 80% or more than 80%, and a second value for a relative one Humidity of less than 80%.

It is possible for the at least one application parameter to be measured by the electrode arrangement or a plasma source having the electrode arrangement. In this way, current and precise values of the application parameter can always be obtained directly. Alternatively or additionally, it is possible for the at least one application parameter to be obtained from the electrode arrangement or the plasma source, in particular from an external source; For example, it is possible for the at least one application parameter to be downloaded by an employer or computer, obtained from a network, or entered by the operator of the electrode arrangement via a suitable interface.

The plasma is preferably generated in ambient air by the electrode arrangement. No separate carrier gas for the plasma generation is therefore supplied to the electrode arrangement. The operation of the electrode arrangement is therefore also influenced in a special way by the ambient temperature and / or relative air humidity in the vicinity of the electrode arrangement.

The electrode arrangement is preferably operated with AC voltage, in particular with a frequency, preferably from at least 2 kHz to at most 100 kHz. The electrode arrangement is preferably operated at a voltage of a few kV, the voltage preferably being selected from at least 1 kV _pp to at most 5 kV _pp , preferably 3.5 kV _pp . According to a development of the invention, it is provided that the electrode arrangement is heated for the determination of the power parameter. For this purpose, the electrode arrangement is particularly preferably heated to a temperature of at least 50 ° C. In this way it is possible to remove any moisture deposited on the surface of the electrode arrangement, which may otherwise impair the measurement.

The plasma power can be determined in various ways:

A preferred option is Fourier (or Power Spectrum) analysis, whereby only the power in the high-frequency part of the spectrum is determined. Since the plasma discharges generate many small “spikes” (practically like delta functions), the plasma power can be measured in the high-frequency range.

In another preferred measurement method, the plasma power is described by the area of a Lissajous figure, which is generated by a phase-space representation of a drive voltage, which is defined as the voltage that is applied to the electrode arrangement for plasma generation by means of a voltage source against a plasma voltage , which is defined as the voltage that is actually present across the electrode arrangement in its operation, accordingly the drive voltage is the unmodified operating voltage of the plasma source and the plasma voltage is the voltage modified / deformed by plasma discharges, phase-shifted voltage relative to the drive voltage, which drops across the electrode arrangement , The individual micro-discharges in the voltage profile are preferably not taken into account here, but rather a suitable averaging. The phase space representation creates a closed curve around an inclusion surface. This inclusion surface contains information about the deformation of the control voltage by the micro-discharges and the phase shift between the control voltage and the plasma voltage and thus represents a measure of the plasma power.

In practice, it is not always possible for various reasons to use this phase space representation and / or to measure the voltage profiles directly. Then control voltage means: applied high voltage or voltage which corresponds to the applied high voltage in form, phase and amplitude; and instead of the plasma voltage, a proxy voltage is measured, which drops across an electronic proxy structure connected in series with the electrode arrangement - in particular also referred to as "proxy measurement" - the proxy voltage separating the two from the micro-discharges (the actual plasma power include) produced effects (deformation and phase shift). The enclosed area of this "proxy measurement" or the proxy voltage in itself also describes the plasma power.

There are various ways to carry out such a "proxy measurement", which shows the plasma power:

Ad 1. The phase space curve of the control voltage versus the proxy voltage is plotted, and the integral of the area thus spanned is formed.

Ad 2. The proxy voltage is measured at a predetermined point in time in the sine curve of the control voltage. The optimal positioning of this point in time of the control voltage is such that the maximum width and / or height of the Lissajous figure is met. This position lies optimally in the area of the greatest temporal gradients and / or phase difference between the control voltage and the proxy voltage.

An easy to define point for this measurement is the zero crossing of the control voltage. The proxy voltage at this point is close to the maximum width or height of the Lissajous figure. The proxy voltage recorded in this way is an easily measurable parameter that depicts the plasma power. For this, a suitable choice of a proportionality factor is required, which can be determined in particular by comparison with the enclosed area of the Lissajous figure.

Due to the "discretization" of the measurement, a "micro discharge" can be hit accidentally with such a "singular" measurement or not. For this reason, a sufficient number of measurements - preferably 256 measurements - are preferably averaged to obtain a reliable result for the plasma power.

According to a development of the invention, provision is accordingly made for the at least one power parameter to be recorded on an electronic proxy structure connected in series with the electrode arrangement, in particular an electronic proxy structure of the plasma source having the electrode arrangement, in particular as a proxy measurement. This enables a simple measurement of the power parameter, which can in particular also be carried out with a small, portable, hand-held device, which is nevertheless characteristic of the plasma power of the electrode arrangement. An electronic proxy structure is understood here to mean, in particular, an electronic component or a plurality of electronic components that are directly or indirectly connected or interact with one another and that are particularly suitable for performing a proxy measurement to determine the at least one power parameter and ultimately the plasma power ,

According to a development of the invention, it is provided that a capacity is used as the electronic proxy structure. In this context, a capacitance is generally understood to mean an electronic structure which at least also behaves capacitively, preferably essentially capacitively, preferably exclusively capacitively. At least one capacitor or a capacitor arrangement, particularly preferably exactly one capacitor, is particularly preferably used as the electronic proxy structure. It has been found that the use of a capacitance as an electronic proxy structure within the scope of the method proposed here permits a particularly reliable statement about the actual plasma power of the electrode arrangement.

The capacity of the electronic proxy structure - hereinafter referred to as proxy capacity - is preferably chosen to be larger, in particular very much larger, preferably by a factor of at least 500 to at most 2000, preferably from at least 750 to at most 1500, preferably of 1000, larger than that Capacity of the electrode arrangement in plasma operation - hereinafter referred to as the arrangement capacity - corresponds.

The _proxy voltage V _proxy relates to the plasma _voltage V _{p |; lsm; l} in the following way:

where C _{p is} the proxy capacity and C _{a is} the placement capacity.

This is explained in more detail using a preferred exemplary embodiment:

(Beginning of the preferred exemplary embodiment.) The arrangement capacity is preferably proportional to a total edge length L (sum of all edge lengths) of a structured electrode of the electrode arrangement, at the edges of which the plasma is generated, and then results as

with the proportionality factor C _L.

The arrangement capacitance is, for example, 109 pF, the plasma voltage is 3.5 kV _pp (peak to peak). Furthermore, the total edge length L is 72 cm. This means that c _L = C _a / L = 1.51 - such a value is typical for SMD electrode arrangements, where c _{L is} in the range 1 <c _L <2.

For technical reasons, one would like to have a value for the proxy voltage of approximately 3 to 5 V _pp . This results in a scaling (where C _p >> C _a ):

The size of the plasma voltage is known from the control voltage (typically a few kV), as is the desired proxy voltage. C _p can be determined for an electrode configuration and the electrode type (eg SMD - that defines CL) which is essentially predetermined by the total edge length L.

For a preferred electrode arrangement, equation (3) gives a guideline value for the proxy capacity of C _p = 100 nF (with V _pr0xy = 3.5 V _pp and V _piaSma = 3.5 kV _pp . (End of the preferred _exemplary embodiment.)

According to a development of the invention, it is provided that at least one value of the proxy voltage is measured as the at least one power parameter at a specific phase angle of the control voltage, in particular when the control voltage crosses zero. A mean value PM of the proxy voltage at the determined phase angle of the drive voltage, averaged over a plurality, in particular a plurality, of periods of the drive voltage is preferably determined as the at least one power parameter:

where in equation (4) V _{proXy, i} (cp) the value of the proxy voltage at the fixed phase angle f - in particular at the zero crossing - of the drive voltage in the period i and where n is a number of periods of the drive voltage over which the averaging takes place. According to a preferred embodiment, n = 256; according to another preferred embodiment, n can have a different or larger value. If n = 256, for a frequency of the control voltage of x kHz, the mean value of the proxy voltage measured continuously once in each period is calculated every l / (4x) seconds if all measurements take place consecutively in successive periods. Especially at high frequencies, measurement is only possible in certain periods (e.g. every second or third period, etc.), or you measure all 256 periods in succession and then leave a gap of a certain number of periods. The corresponding procedure must of course be taken into account when determining the plasma dose.

According to a further development of the invention, it is additionally or alternatively provided that an open circuit proxy voltage is measured on the electronic proxy structure with an open circuit voltage applied to the electrode arrangement, in which no plasma is generated on the electrode arrangement, with the drive voltage applied to the electrode arrangement, in which a plasma is generated on the electrode arrangement, the proxy voltage and preferably the plasma voltage are measured, and wherein as the at least one performance parameter a plasma capacity is determined on the basis of the open circuit voltage, the open circuit proxy voltage, the drive voltage or the plasma voltage, and the proxy voltage , In this way, the plasma power can be determined even more precisely.

The control voltage and the plasma voltage can alternatively be used here.

An open-circuit voltage is understood here to mean an AC voltage in which no plasma discharge occurs at the electrode arrangement when the open-circuit voltage is applied to the electrode arrangement. In contrast, if the drive voltage is applied to the electrode arrangement, plasma discharges are induced, so that plasma is generated on the electrode arrangement. The open circuit proxy voltage is the AC voltage that is measured on the electronic proxy structure when the open circuit voltage is present on the electrode arrangement.

The open circuit voltage and the open circuit proxy voltage are preferably measured as peak-to-peak values. Likewise, the control voltage, the Plasma voltage and / or the proxy voltage are measured as peak-to-peak values.

A plasma capacity is understood in particular to mean the capacity of the plasma, that is to say the capacity which is only generated by the plasma, in particular by the local charge separation due to numerous surface micro-discharges in the region of the electrode arrangement. In contrast, the aforementioned arrangement capacity includes both the plasma capacity and a system capacity. The system capacity is the capacity of the electrode arrangement in the absence of plasma discharges.

The plasma capacity is also determined in particular on the basis of the - known - proxy capacity.

The idle proxy voltage is preferably initially measured at the idle voltage - in particular once per start-up of the electrode arrangement. The control voltage or plasma voltage on the one hand and the proxy voltage on the other hand are preferably recorded continuously or at certain times / in certain periods in the operation of the electrode arrangement.

The starting point for this procedure is therefore two measurements: The first measurement is measured with the open circuit voltage V _L below an ignition voltage necessary for the plasma ignition. The relevant equation is analogous to equation (3), only the system capacitance Cs is determined in this way, essentially the capacitance caused by the electrode structure and the dielectric: r = Cs

V,. (5)

^P VL, proxy

C _{p is} again the proxy capacity and V _{L, proxy} is the open circuit _proxy voltage. Since there is no phase shift, the peak-to-peak voltage is used here for both the open-circuit voltage and the open-circuit proxy voltage for reasons of the accuracy of the measurement. In the second step, the measurement is then carried out under the operative operating voltage, that is to say the drive voltage or preferably the plasma _voltage V _piaS ma, the peak-peak voltage also being taken here in each case as well.

The arrangement _capacity , C _a , determined in the second measurement is composed of the plasma _capacity C _piasma generated by the plasma and the system capacity (essentially generated by the electrode structure and the dielectric) Cs, both capacitances being arranged in series. The relationship is

From these equations (5) and (6) and the two proxy measurements of the idle proxy voltage VL, _p r _o xy and the proxy voltage V _per xy, and dendazugehörigen values of the no-load voltage V _L and the plasma voltage V _PIAs ma (or according to the Control _voltage ), C _piaSma can be easily calculated as a performance parameter:

Cpi _asma is a more direct measure of the plasma power as _a C because it is directly proportional to the generated by the plasma charges.

By averaging a number of such measurements, which is preferred according to the invention, the measurement error is reduced in accordance with the statistical accuracy.

It is therefore preferable to use the values of the corresponding voltages averaged over periods of the drive voltage or open circuit voltage, in particular namely the open circuit voltage, the open circuit proxy voltage, the drive voltage or the plasma voltage, and the proxy voltage to calculate the plasma _capacity C _piasma over a plurality, in particular a plurality ,

An assignment of the power parameter to the actual plasma power is preferably stored in a control device for controlling the electrode arrangement, preferably as a simple factor or as a more complex, preferably at least injective, preferably bijective function, which unequivocally realizes a measured value of the power parameter Allocates plasma power.

According to a development of the invention, it is provided that the performance parameter is compared with a first, upper target parameter value and with a second, lower target parameter value. The first, upper target parameter value is larger than the second, lower target parameter value. The at least one action is selected depending on whether the performance parameter value is divided into a value by the first target parameter value and the second target value. Parameter value limited target parameter range falls. The first target parameter value and the second target parameter value thus span a target parameter range into which the performance parameter is intended to fall; this means that the electrode arrangement will function properly if the performance parameter falls within the target parameter range. If, on the other hand, the power parameter is smaller than the second, lower target parameter value or larger than the first, upper target parameter value, the electrode arrangement does not function properly and can either not be used or can only be used to a limited extent. The at least one action can in particular also be selected depending on how far the performance parameter is spaced from the first, upper target parameter value or from the second, lower target parameter value - outside the target parameter range. It is in particular possible to separate an area for a yellow alarm and an area for a red alarm by corresponding further limit values.

The first, upper target parameter value takes into account an upper power limit for the plasma generation, this upper power limit being able to be exceeded, for example, by erosion of a dielectric of the electrode arrangement, deposition on the dielectric, leakage current formation or other similar effects which increase the power consumption of the electrode arrangement. The lower, second setpoint parameter value takes into account a lower power limit of the electrode arrangement, which may be lower, for example, due to contamination, deposition and / or erosion of conductive components of an electrode of the electrode arrangement, or by other similar effects which reduce the power consumption of the electrode arrangement.

Each electrode arrangement is preferably characterized in the course of an initial test, the first and second target parameter values being defined individually for the respective electrode arrangement and application (for example oxygen, nitrogen or intermediate mode) and preferably in an electronic memory device assigned to the electrode arrangement, for example an RFID chip or the like. In this way, intra-individual manufacturing variations can be recorded and a functional area that is as precise as possible and intended can be specified for the individual electrode arrangement and application task. These individual threshold values can then be transmitted for each electrode arrangement, even when the electrode arrangement is replaced in an existing plasma source, in particular by reading out the memory device. The storage device, for example the RFID chip or another data carrier is preferably connected to the electrode arrangement in a captive manner and is arranged and / or exchanged together with the latter on the plasma source.

According to a development of the invention, it is provided that the electrode arrangement is operated for a predetermined period of time before the at least one power parameter is determined. In this way it can be ensured that constant operating conditions and / or a balance has / have been set for the operation of the electrode arrangement, so that the performance parameter for continuous operation is correctly recorded.

However, it is also possible that - in particular for dose monitoring - the at least one performance parameter is continuously and continuously recorded from the start of operation of the electrode arrangement, in particular from the start of treatment. In this way, the entire applied plasma dose can be reliably detected, the temporal development of the performance parameter possibly being irrelevant or being automatically taken into account in any case.

According to a development of the invention, it is provided that the comparison result, the at least one performance parameter, and / or the applied plasma dose is / are logged in an electronic storage device for later retrieval. The electronic storage device can be integrated directly into a control device for controlling the electrode arrangement, but can also be provided externally for this purpose. In particular, it is possible for the logging to be carried out in an external employer who is operatively connected to the control device for the electrode arrangement via a wired or wireless data connection, for example WLAN and / or Bluetooth. The comparison result, which automatically logs at least one performance parameter and / or the applied plasma dose, is / are particularly preferably linked and / or particularly preferably linked to at least one metadata, for example a time stamp, an indication of a place of use of the electrode arrangement, an indication of a purpose or a type of use of the electrode arrangement, details of certain parameters of the operation of the electrode arrangement, or the like. In this way, a log book for the operation of the electrode arrangement can be created, so that its function or functionality and readiness for use, or generally its operation can be tracked over time. It is preferably also possible to remotely monitor, read out and / or control the electrode arrangement via a wired or wireless active connection, in particular a radio connection, preferably WLAN and / or Bluetooth, particularly preferably via Internet access and / or via a smartphone app.

According to a development of the invention, it is provided that an electrode arrangement is checked and / or monitored, which is set up to generate surface micro-discharges in ambient air. Such an electrode in particular can be checked and / or monitored using the method proposed here. The plasma is generated flat or along a line, in particular on the edges of a structured electrode of the electrode arrangement, directly in ambient air.

In a specific exemplary embodiment, a spacer is assigned to the electrode arrangement in order to ensure a specific distance from a surface to be treated. The spacer is preferably designed such that it encloses a volume with the surface to be treated during operation of the electrode arrangement, so that the plasma is generated by the electrode arrangement in a closed volume.

According to a development of the invention, it is provided that an electrode arrangement is tested and / or monitored, which has a first, in particular flat electrode and a second, preferably flat electrode. The electrode arrangement also has a dielectric, by means of which the first electrode and the second electrode are spaced apart from one another, the first electrode and the second electrode in each case — viewed in the stacking direction of the stack from the electrodes and the dielectric on opposite sides of the dielectric — in mechanical Are in contact with the dielectric. In particular, they can be arranged on opposite surfaces of the dielectric or at least partially embedded in the dielectric. The first electrode is particularly preferably arranged close to a first side of the dielectric, the second electrode being arranged close to a second side of the dielectric opposite the first side, for example by vapor deposition, screen printing, physical or chemical vapor deposition, by laying on or Press on, stick on, or in any other suitable way.

In this way, an electrode arrangement is created which is suitable for, on one of the two electrodes on one side of the dielectric, in particular on edges of this electrode, Generate surface micro-discharges and thus generate a non-thermal plasma without a treated surface having to be arranged between the electrodes and / or an electrode and the dielectric, and furthermore without the surface to be treated itself having to be switched as a counter electrode. Furthermore, it is possible to generate the non-thermal plasma at least largely uniformly on the surface on which the surface micro-discharges are ignited, so that uniform and constant conditions and plasma parameters can be achieved via this surface.

According to one exemplary embodiment, the second electrode is pressed or pressed against the second side of the dielectric, so it is preferably in contact with the second side of the dielectric, in particular under pretension or contact pressure. This enables a tight and stable arrangement of the second electrode on the second side of the dielectric without an air gap, which is favorable for the efficiency and the plasma generation rate of the plasma source. At the same time, the electrode arrangement can be manufactured in a simple manner, in particular since the second electrode can be manufactured separately from the dielectric and then only has to be placed on it and pressed or pressed on. The second electrode is also very easy to replace.

It is possible that the first electrode is also pressed or pressed against the first side of the dielectric, in particular under pretension or contact pressure. However, the first electrode is particularly preferably coated on the dielectric, in particular vapor-deposited.

The second electrode preferably has a periodic structure made up of a plurality of identical structural elements, and / or the second electrode has at least one structural element with at least one recess delimited by edges. The second electrode is accordingly designed as a structured electrode which has edges on which surface micro-discharges can be ignited.

The edges delimiting the recess have, for example, an edge length of at least 0.5 mm to at most 10 mm, preferably from at least 1 mm to at most 8 mm, preferably from at least 2 mm to at most 7 mm, preferably from 5 mm to one another within each recess.

Additionally or alternatively, it is preferably provided that the second electrode has a plurality of structural elements, the individual structural elements being at a distance of have at least 0.5 mm to at most 10 mm, preferably from at least 1 mm to at most 8 mm, preferably from at least 2 mm to at most 7 mm, preferably from 5 mm.

However, it is also possible to use a linear electrode (line electrode) or linear electrodes.

The first electrode is preferably provided with an insulating layer and / or a casting compound.

According to a development of the invention, it is provided that a high voltage, in particular an AC voltage, preferably with an amplitude of at least 1 kV _pp to at most 5 kV _pp , and / or with a frequency of at least 2 kHz to the first electrode during operation of the electrode at most 100 kHz. The frequency is preferably chosen in particular as a function of the properties of a high-voltage source used. The second electrode is preferably grounded or grounded.

In operation of the electrode arrangement for treating a surface, the first electrode preferably faces away from the surface to be treated, the second electrode facing the surface to be treated. The stacking direction of the stack of the electrode arrangement comprising the first electrode, the second electrode and the dielectric extends obliquely or transversely, preferably perpendicular to the surface to be treated. The electrical safety is thus particularly high with regard to the surface to be treated, since, when used as intended, it can at most come into contact with the second, grounded or grounded electrode.

At the same time, the second electrode is the one at which the surface micro-discharges are ignited and thus the plasma is generated, which can act unhindered on the surface to be treated.

In the context of the method, an electrode arrangement of a plasma source is preferably checked and / or monitored, which is set up to generate a non-thermal plasma and has an electrode arrangement, in particular an electrode arrangement according to one of the exemplary embodiments described above. In addition to the electrode arrangement, the plasma source preferably has a control device for controlling the Electrode arrangement, in particular for energizing the same, and an electronic storage device, namely in particular the previously described electronic storage device associated with the electrode arrangement. The control device is in particular set up to carry out a method according to one of the previously described embodiments.

According to one exemplary embodiment, the plasma source is designed as a hand-held device which can be held and carried by a user, preferably with one hand. The plasma source can in particular have a size at which it can be operated and carried with one hand, for example the size of a telephone receiver or a shower head.

The plasma source can also be designed as a larger, stationary and / or wired device.

The plasma source also preferably has means for communicating with a user, these means preferably being selected from a group consisting of acoustic communication means, in particular a loudspeaker, optical communication means, in particular signal lights, preferably light-emitting diodes, a display means for displaying graphics and / or texts, in particular at least one display, and vibration means for generating a vibration of the plasma source. In the case of larger systems (e.g. water treatment systems for apartments, houses, blocks of houses), communication preferably takes place with a - remote or central - operator of the system, in particular via the Internet and / or via wireless LAN, Bluetooth, or other wireless connections, e.g. also on a smartphone with an app. The operator can also operate several such systems and manage them centrally.

According to one exemplary embodiment, the plasma source can be battery or accumulator-operated and, in this respect, can be operated wirelessly and in particular without contact with a fixed, larger device. Since the plasma is generated in ambient air, the plasma source preferably also has no gas supply for supplying a carrier gas.

In the following, fundamental considerations regarding the previously described method for testing and / or monitoring an electrode arrangement for generating a non-thermal plasma are explained in more detail: Flat or linear electrode arrangements (e.g. DBD - Dielectric Barrier Discharge SMD - Surface Micro Discharge, i.e. electrode arrangements for generating surface micro-discharges coated SMD, regardless of their geometry) vary in their plasma power depending on environmental conditions. This applies in particular to the air humidity, which can have a strong influence depending on the materials used, in particular on the dielectric. This is partly due to the chemical conditions of the air (eg excitation probabilities, dissociation, ionization), which is mainly due to the varying air humidity, but also due to condensation on the electrodes and absorption and diffusion into the dielectric material. The latter can be reduced by, for example, “burning in” the electrode arrangement before each use - the former cannot be compensated for without knowledge of the environmental conditions. In addition, the electrode arrangement can become old and dirty due to prolonged use, which impairs functionality. “Aging effects” include, for example, corrosion, deposits, and surface changes that can occur with prolonged use and can impair performance.

In most cases, the functionality of the electrode arrangement is not answered by a simple yes / no decision if one only ascertains whether current is flowing. For example, for hygiene, surface treatment, textile treatment, water treatment, treatment of food, seeds, skin diseases and wounds, it is crucial that the plasma dose is sufficient for the respective application in order to inactivate pathogens (bacteria, viruses, spores) to the desired degree. “Plasma dose” is the product of the plasma generation rate (plasma power) multiplied by time. Plasma chemistry, which is controllable and thus defines the area of application, is also important. Plasma chemistry can also depend on plasma performance (e.g. in the air, either oxygen or nitrogen chemistry can be chosen as dominant, or an intermediate range or a sequential variable treatment).

Method:

In general, the typical problem is as follows:

The decisive property of the plasma source is the inactivation of pathogens - mainly bacteria and / or the inactivation of allergens, odor molecules or other undesirable or dangerous molecules (decontamination) - up to one required log reduction either in a predetermined time t, or with a predetermined target plasma dose or the resulting dose of reactive species. For the control of the plasma source, two activities are therefore useful: 1. The functional test before use (to ensure that the plasma source works as required, and 2. The monitoring during the treatment to ensure the proper functionality of the plasma source continuously to be recorded and, if necessary, the treatment is automatically terminated automatically or the operator is informed when the required target plasma dose is reached.

Example of bacterial inactivation in a given time:

1. Functional test

Ad 1. Appropriate bacteria tests must be carried out for the desired treatment time. These define the plasma power that is preset on the device.

Ad 2. The decisive parameter for this is the plasma power PL - i.e. how much energy is put into generating a non-thermal cold atmospheric plasma per second?

The plasma is generated in the SMD electrode in millions of micro-discharges, which can be seen in the current curve as tight “spikes” - each spike with a typical duration of a few 10 nanoseconds. This high frequency component is e.g. not directly measurable for a small handheld device, the effort is too great. For a larger system, the effort is also high, but more likely to be realized - unless a simpler, reliable process exists.

Ad 3. It is therefore necessary to find a measured variable which can be carried out by a simple measurement which allows a direct conclusion to be drawn about the plasma power PL - a power parameter PM. There is no need for a linear relationship between the power parameter PM and the plasma power PL; rather, an unambiguous, preferably bijective relationship between these variables is sufficient. However, a linear relationship represents a particularly simple embodiment, which is why it is assumed here as an example. This performance parameter PM should apply to all environmental conditions - ie PM / PL should ideally be constant, regardless of temperature and humidity. Then PM can be used to uniquely identify the plasma power PL of the plasma source in every application - by means of a simple first “scaling factor” Sl = PL / PM.

Ad 4. The electrode arrangement can have "aging effects" that do not affect the effectiveness, but can change the plasma power.

The ratio Sl = PL / PM should ideally also be constant for electrode arrangements with signs of aging, in the optimal case this ratio should always be the same, regardless of the age of the electrode arrangement. However, this is not to be expected because the electrode arrangements can change (e.g. due to corrosion, oxidation, deposition). Therefore, aging effects must be examined in long-term tests, and the electrode arrangement may have to be replaced after a certain number of applications.

Ad 5. If the measurement takes place under different environmental conditions than the final operating conditions (not uncommon for a functional test before use), the scaling from the environmental to the operating conditions must also be determined experimentally.

This is the case, for example, if a function test is carried out in a normal room environment, but the application takes place in a moist, closed volume (this corresponds, for example, to water treatment or, if necessary, wound treatment). This requires an additional second scaling factor (S2), which is determined experimentally. The scaling from the “proxy measurement” of the performance parameter PM to the final application area is then given as the total scaling factor S from the product SlxS2 = S.

Ad 6. The functionality of the electrode arrangement can generally also be carried out under environmental conditions (temperature, relative humidity) which are not known.

So that the scaling to the application area can still be used, it is important that the ratio PL / PM does not have a great variability with air humidity. In addition, it is advisable to determine a "standard range" for air humidity (in which the functionality will be checked with a high degree of probability) and to carry out the scaling from there. Ad 7. Before use, the electrode arrangement may be “burned in” to remove storage effects (eg through condensation). Then the performance parameter PM is measured - under the prevailing (only approximately known or even unknown) environmental conditions.

The scaling factor S is applied to this measurement in order to obtain the calculated proxy plasma power under operating conditions. The intra-individual and inter-individual variation in the electrode arrangements must be taken into account as the “bandwidth” of the scaling factor.

Ad 8. Another complication - the electrode can be partially soiled, so that the plasma power is reduced compared to a clean electrode.

It must be ensured that the values PM and PL are linked in the same way - i.e. Sl is ideally independent of the degree of pollution. The same applies to the second scaling factor S2. These relations also have to be verified experimentally.

Ad 9. In the present case (especially medical application or water treatment) there is another complication. The actual “measure” is not the plasma power - it is the bactericidal effect of the plasma, as noted at the beginning. This is described by the integrated plasma dose in a preset operating mode.

Without continuous monitoring and summation of the plasma dose - only based on the preliminary functional test - the following applies: The duration of use that exceeds the required minimum dose with an additional safety factor is predetermined by appropriate tests and should always remain the same. The "plasma dose" is thus only defined by the plasma power in the area of application, which can be Steps can be determined.

In order to guarantee successful treatment, a lower threshold, PSU, for the plasma power in the application must be determined experimentally. The threshold value for PM recorded in the functionality test is then PU = PSU / S. If the plasma power PL is below the threshold value PSU, the electrode arrangement does not work well enough to achieve the required effect (for example 3-4 log bactericidal effectiveness). Provided that the overall scaling factor S and the threshold value PSU have been selected with sufficient care so that all manufacturing tolerances and expected environmental changes to the (unknown) environmental conditions are included in the function test, the value PM> PU determined in this way guarantees that the plasma output sufficient to fulfill the required purpose.

So the first condition for positive functionality is:

PM> PU, with the lower threshold PU = PSU / S.

A second condition for positive functionality is given by an upper threshold, PSO, which must not be exceeded. Various disturbances (e.g. age-related erosion of the dielectric, deposition of conductive erosion products on the dielectric, formation of leakage currents, etc.) can cause the plasma output to rise above the normal operating value. In principle, the electrode arrangement is still operational, but there are two important changes that have to be considered:

A. The electrode arrangement is damaged and / or modified and therefore no longer comparable with the electrode arrangement used as a reference measurement (e.g. in preliminary tests, laboratory or in the preclinical);

B. The electrode arrangement could change from the oxygen mode to the nitrogen mode (if the power is sufficiently increased). This also changes the bactericidal effect and is not compatible with the preliminary tests, laboratory measurements or preclinical tests.

So the second condition for positive functionality is:

PM <PO, with the upper threshold PO = PSO / S.

In order to capture this logical chain and use it to generate safe operating parameters "PSU and PSM" for all environmental conditions, a large number of measurements are necessary.

The plasma power PL must be measured independently with the corresponding effort, and both PL and PM must be determined and related for all relevant environmental conditions. This has to be done for different levels of pollution and Aging states of the electrode arrangement are repeated. All the parameters generated in this way must be correlated with their bactericidal action BE using bacterial tests. If all of these data sets are available, the acceptable threshold PS can be determined.

So that intra-individual fluctuations (e.g. due to manufacturing tolerances) are also included, these measurements must be carried out for a representative set of electrode arrangements and the fluctuations (typically 3 s) must be taken into account.

Example: The required number of measurements (PM and PL at 3 temperature values with 7 air humidity values each, plus 3 bacterial measurements and controls) for 4 degrees of contamination - results in approx. 700 measurement values per device - i.e. more than 7,000 measurements for the required safety statistics!

From a series of such measurements, the threshold value for the plasma power is determined, which is necessary to produce the desired bactericidal effect in the given treatment time (e.g. 1 minute).

The threshold value was determined to be 1 watt for a specific electrode arrangement.

The degree of pollution can be important. For example, a specific exemplary embodiment of the electrode arrangement still works if it is contaminated by more than 50%. The bactericidal effect can hardly be determined until 80% contamination.

It should also be mentioned that each new electrode arrangement has to be tested with a similar effort in order to enable a reliable function test that applies to all relevant environmental conditions.

Of course, every new plasma source (electrode arrangement, high-voltage source and control device) must be tested for safety aspects in accordance with the requirements pre-clinical and in clinical studies.

2. Monitoring

The measurement variable mentioned in the function test for determining the plasma power PL (ie the power parameter PM) is also used for monitoring. This performance parameter PM with the simple first “scaling factor” Sl = PL / PM is preferably determined continuously. Since in the case of monitoring initial settling processes are the main reason for variability - but otherwise the environmental conditions should be relatively constant - further scaling is not necessary.

Two or three steps are required for monitoring: a) Continuous checking whether the plasma power is within the specified operative range. If this is not the case in the course of the treatment, the treatment is either discontinued (this would be, for example, if the plasma output reaches the previously defined “red area”), or the user is informed in a suitable manner that the plasma source is no longer in the actual operational area works (that would be, for example, if the plasma power reaches the previously defined "yellow area"). The transient process is an exception, but it e.g. can be taken into account by a temporary measure.

b) The summation of the plasma power and determination of the applied plasma dose. If the predetermined target plasma dose is reached, the treatment can be ended - either automatically or manually after notification of the user.

c) It may also be decided that e.g. after the "plasma-on" phase, the treatment is continued without further plasma generation in order to allow long-lasting species to continue to work (e.g. in closed volumes - in wound treatment, in water treatment, in seed treatment, etc.). This can also be taken into account in the monitoring and must be defined in advance in the operating mode.

The invention is explained in more detail below with reference to the drawing. Show:

Ligur 1 is a schematic representation of an embodiment of a method for testing and / or monitoring an electrode arrangement in Lorm of a flow diagram, and

Ligur 2 is a schematic representation of an embodiment of a plasma source.

1 shows a schematic representation of an embodiment of a method for testing and / or monitoring an electrode arrangement for generating a non-thermal Plasma in the form of a flow chart. In a first step S1, the electrode arrangement is put into operation, in particular a plasma source having the electrode arrangement being switched on.

In a second step S2, at least one power parameter is determined that characterizes a plasma power of the electrode arrangement.

In a third step S3, the at least one performance parameter is compared with at least one predetermined target parameter value, from which a comparison result is obtained. Alternatively or additionally, the at least one performance parameter is preferably recorded over time.

In a fourth step S4, a puncture or ability to puncture the electrode arrangement is assessed on the basis of the comparison result.

In a fifth step S5, an action is preferably selected depending on the comparison result or on the performance parameter recorded over time. Depending on the comparison result, this action preferably includes the output of an “in order” signal, the output of a “need for action” signal, the output of a “non-order” signal, the notification of an instantaneous plasma power and / or a plasma dose to an operator of the electrode arrangement, the adaptation of an operating time of the electrode arrangement to the comparison result, the termination of the operation of the electrode arrangement, or a continuation of the operation of the electrode arrangement without further measures, in particular without signal or message output. The signal can be output in particular in the form of light or light signals, for example the activation of a green, yellow or red light, in particular an LED. Alternatively or additionally, a text or a graphic symbol can be shown on a display. An acoustic output of a message or warning is also possible, as is also the output of a message or warning by generating a targeted vibration of the electrode arrangement, in particular the plasma source, which has the electrode arrangement. For the selection of the action, predetermined areas are preferably defined for the correspondence or deviation of the at least one performance parameter with / from the at least one predetermined target parameter value, the action being selected depending on which of the predetermined areas the comparison result falls into. The method is preferably carried out immediately after start-up, particularly preferably after each start-up of the electrode arrangement. Alternatively or additionally, it is provided that the method is carried out repeatedly, in particular periodically, at predetermined operating times, stochastically or event-oriented, or continuously during operation of the electrode arrangement, that is to say during its actual use, in particular for treating a surface. Such a repeated execution of the method is indicated here by a dashed arrow P, the arrow P here linking the fifth step S5, hence the selection of the at least one action, to the second step S2, namely the determination of the at least one performance parameter. During operation of the electrode arrangement, it typically remains switched on permanently, so that a repetition of the first step S1 is not required.

An event-controlled implementation of the method is understood in particular to mean that the method is started by external requirements, for example by manual interaction of the operator of the electrode arrangement.

The at least one predetermined target parameter value is preferably predefined constant. Alternatively, it is possible that the at least one predetermined target parameter value is selected as a function of at least one application parameter of the electrode arrangement, it being possible in particular to store it in the form of a mathematical relationship, a characteristic curve or a characteristic field. The at least one application parameter preferably comprises an ambient temperature of the electrode arrangement and / or a relative atmospheric humidity in an environment, in particular an immediate environment, very particularly a treatment environment of the electrode arrangement, that is to say an environment in which the non-thermal generated by the electrode arrangement Plasma a treatment, in particular a surface treatment, a water treatment, a treatment of food or seeds is carried out.

The plasma is generated by the electrode arrangement, in particular in ambient air, so that the relative air humidity in the vicinity of the electrode arrangement is relevant for the plasma generation.

The electrode arrangement is preferably heated at least in regions for the determination of the power parameter, it being possible in particular to heat it to a temperature of at least 50 ° C. In this way, on the surface of the electrode assembly accumulated moisture are removed, which could otherwise impair the measurement.

The comparison result, the at least one performance parameter and / or the applied plasma dose is / are preferably logged for later retrieval in an electronic storage device. A logged value is preferably stored with at least one metadata, in particular together with a place of use, a purpose, a time stamp and / or further metadata, preferably automatically. These parameters can then be read out and / or graphically displayed at a later point in time in order to monitor the operation of the electrode arrangement and to assess its function or functionality over time.

The electrode arrangement is preferably set up to generate

Surface micro-discharges in ambient air.

An electrode arrangement is preferably used which has a first electrode and a second electrode, the first electrode and the second electrode being spaced apart from one another by a dielectric and in particular being provided on different sides of the dielectric in mechanical contact with the dielectric. The first electrode and the second electrode are preferably flat. The second electrode is preferably designed as a structured electrode or structured electrode which has a plurality of edges on which surface micro-discharges can be ignited.

A high voltage, in particular an alternating voltage, is preferably applied to the first electrode, the second electrode being grounded or grounded. When the electrode arrangement is used to treat a surface, the second electrode preferably faces the surface to be treated, which increases the electrical safety of the operation of the electrode arrangement.

FIG. 2 shows a schematic illustration of an exemplary embodiment of a plasma source 100 with an electrode arrangement 1, shown only schematically, for generating a non-thermal plasma. The plasma source 100 also has a control device 101, which is set up to control the electrode arrangement 1. The control device 101 here has, in particular, a voltage source 103, by means of which an AC voltage can be applied to the electrode arrangement 1 as a control voltage. In addition, the control device has an electronic proxy structure 104 which can be connected in series with the electrode arrangement 1, here connected. The control device 101 is set up to detect the at least one power parameter on the electronic proxy structure 104 connected in series with the electrode arrangement 1. The electronic proxy structure 104 is designed here in particular as a capacitance 105.

At least one value, in particular an average value, of an alternating voltage V (t) - the proxy voltage - falling across the electronic proxy structure 104 at a specific phase angle of the drive voltage - is measured, in particular averaged over a plurality of periods of the drive voltage, in particular according to the equation (4) given above. The proxy voltage is preferably detected in a time-dependent manner by a voltage measuring device 107.

Additionally or alternatively, it is preferably provided that an open circuit proxy voltage is measured on the electronic proxy structure 104 with an open circuit voltage applied to the electrode arrangement 1, in which no plasma is generated at the electrode arrangement 1, with the drive voltage applied to the electrode arrangement 1, in which a plasma is generated on the electrode arrangement 1, the proxy voltage and preferably the plasma voltage are measured, and wherein as the at least one power parameter a plasma capacity based on the open circuit voltage, the open circuit proxy voltage, the drive voltage or the plasma voltage, and the proxy voltage and preferably the proxy capacity is determined. In this way, the plasma power can be determined more precisely.

The performance parameter is preferably compared with a first, upper target parameter value and a second, lower target parameter value, the at least one action being selected as a function of whether the at least one performance parameter is converted into a by the first target parameter value and the second target parameter value limited target parameter range falls.

A large series of measurements was carried out on an exemplary embodiment of the plasma source 100 in an environmental chamber in order to determine the correlation between the “real plasma power” and the “proxy measurement” using the circuit diagram shown in Ligur 2.

The result of hundreds of such measurements shows that there is a very good correlation between the real and the proxy determination of the plasma power and that Variation between different plasma sources 100 and / or electrode arrangements 1 of the same type is very small.

The good correlation exists in all environmental conditions that were in the test area.

This means that if the plasma dose (also maximum dose or minimum dose) has been determined experimentally for a specific application, this plasma dose can be stored in the control device - and as soon as the specified value is reached, the treatment is ended automatically. This means that the treatment is always independent of intra-individual variations of different plasma sources of the same design in their plasma performance.

Additional security features can be installed. For example, if the desired target plasma dose has still not been reached after a maximum time, an error message can occur.

If the plasma source is operated in oxygen mode (i.e. the plasma power is below a predefined threshold value) or in nitrogen mode (i.e. the plasma power is above the predefined threshold value), the plasma dose can be defined differently and entered as a reference.

If the plasma source is operated in oxygen mode (ie the plasma power is below a predefined threshold value) and subsequently in nitrogen mode (ie the plasma power is above the predefined threshold value), the plasma dose can first be defined for the oxygen mode and entered as a reference , then the time until the ozone concentration is reduced in nitrogen mode can be entered as a second reference.

Other operating modes can also be easily programmed on the basis of the monitor method proposed here.

A preclinical study was carried out on an exemplary embodiment of the plasma source 100 in order to determine a safe therapeutic window for treatments.

Effectiveness studies were carried out first. It was found that the plasma source 100 very effectively inactivates bacteria - including multi-resistant germs - and fungi. High reductions of four to five orders of magnitude are already achieved here during a treatment period of only 60 seconds.

Further investigations showed that bacterial biofilms can also be inactivated. Reductions of three orders of magnitude were achieved within 60 seconds of treatment. A complete reduction could be achieved after a treatment period of 10 minutes.

Furthermore, safety examinations were carried out, in particular vitality examinations on eukaryotic cells (primary fibroblasts and keratinocytes); mutagenicity; Wound healing assays (for analyzing cell proliferation), and ex vivo skin studies (histology, apoptosis or necrosis analysis).

These examinations show that even in the worst-case scenario of individual eukaryotic cells, there is no damage with treatment times of up to 3 minutes. The mutagenicity tests showed no induction of mutations for any plasma treatment period (tested up to 5 minutes), and the ex vivo skin tests also showed no damage for any plasma treatment period. This suggests an even larger therapeutic window than that specified here.

With the method described here, an initial and also permanent checking and / or monitoring of an electrode arrangement for generating a non-thermal plasma without disrupting its normal operation is possible, which in particular significantly increases the safety of the operation of the electrode arrangement itself and the respective use of the electrode arrangement ,

Claims

EXPECTATIONS

1. A method for testing and / or monitoring an electrode arrangement (1) for generating a non-thermal plasma, comprising the following steps:

Determining at least one power parameter characterizing a plasma power of the electrode arrangement (1); a) temporal recording of the at least one performance parameter; and / or b) - comparing the at least one performance parameter with at least one predetermined target parameter value, and obtaining a comparison result;

- Assessing a function or functionality of the electrode arrangement (1) based on the comparison result, and preferably

- Selection of at least one action depending on the comparison result.

2. The method according to claim 1, characterized in that the action is selected from a group consisting of an output of an "in order" signal, an output of a "need for action" signal, an output of a "not in order" “Signal, a notification of a current plasma power and / or a plasma dose to an operator of the electrode arrangement, (1) an adaptation of an operating time of the electrode arrangement (1) to the comparison result, an end of operation of the electrode arrangement, (1) and continuing the operation of the electrode arrangement (1) without further measures.

3. The method according to any one of the preceding claims, characterized in that the method immediately after starting up the electrode arrangement (l), and / or repeatedly, in particular periodically, at predetermined operating times, stochastically or event-controlled, or continuously during operation of the electrode arrangement (l ) is carried out.

4. The method according to any one of the preceding claims, characterized in that the at least one predetermined target parameter value a) is constantly predetermined, or b) is stored as a function of at least one application parameter of the electrode arrangement (1), the at least one application parameter preferably being selected is from a group consisting of an ambient temperature of the electrode arrangement (1) and a relative air humidity in an environment of the electrode arrangement (1).

5. The method according to any one of the preceding claims, characterized in that the at least one power parameter is detected on an electronic proxy structure (104) connected in series with the electrode arrangement (1).

6. The method according to any one of the preceding claims, characterized in that as the at least one power parameter at least one value of a proxy voltage falling across the electronic proxy structure (104) to a certain phase angle of a control voltage applied to the electrode arrangement (1), in particular at a zero crossing of the control voltage is measured.

7. The method according to any one of the preceding claims, characterized in that as the at least one power parameter an average value of the proxy voltage at the determined phase angle of the drive voltage, averaged over a plurality, in particular a plurality, of periods of the drive voltage is determined.

8. The method according to any one of the preceding claims, characterized in that on the electronic proxy structure (104)

- At an open circuit voltage applied to the electrode arrangement (1), in which no plasma is generated at the electrode arrangement (1), an open circuit proxy voltage is measured, wherein

- At a control voltage applied to the electrode arrangement (1), in which a plasma is generated on the electrode arrangement (1), a proxy voltage is measured, and wherein a plasma capacity is determined as the at least one power parameter on the basis of the open circuit voltage, the open circuit proxy voltage, the drive voltage or a plasma voltage dropping across the electrode arrangement (1) when the drive voltage is applied, and the proxy voltage.

9. The method according to any one of the preceding claims, characterized in that a capacitance (105), in particular a capacitor, is used as the electronic proxy structure (104).

10. The method according to any one of the preceding claims, characterized in that the at least one performance parameter is compared with a first, upper target parameter value and with a second, lower target parameter value, the at least one action being selected depending on whether the at least one power parameter falls within a desired parameter range limited by the first desired parameter value and the second desired parameter value.

11. The method according to any one of the preceding claims, characterized in that the electrode arrangement (1) is operated for a predetermined period of time before the determination of the at least one power parameter.

12. The method according to any one of the preceding claims, characterized in that the comparison result, the at least one performance parameter, and / or an applied plasma dose for later retrieval in an electronic storage device of the electrode arrangement (1) - in particular automated, preferably with at least one metadata - is logged.

13. The method according to any one of the preceding claims, characterized in that an electrode arrangement (1) is checked and / or monitored, which is set up to generate surface micro-discharges in ambient air.

14. The method according to claim 13, characterized in that an electrode arrangement (1) is tested and / or monitored, which has a first, preferably flat electrode, a second, preferably flat electrode and a dielectric, the first electrode and the second electrode spaced from each other by the dielectric and are each arranged in direct mechanical contact with the dielectric.

15. The method according to any one of claims 13 or 14, characterized in that a high voltage, in particular an alternating voltage, is applied to the first electrode, the second electrode being connected to ground or grounded.