The present invention relates to a device for treating cells used in medical, environmental, food applications, and bio-based industries (including yeast, bacteria, microalgae, as well as plant or animal cells and cell tissue production systems, in particular targeting inactivation, the extraction of bioactive compounds, and/or the stimulation of cell growth and/or cellular compounds.

It is known that prokaryotic and eukaryotic cells are influenced by the action of electric fields. Stimulation of cell growth, as well as cell death, inactivation of microorganisms, or specific extraction of cell constituents can occur, depending on the ap plied electric field strength (e.g. Buchmann L and Mathys A (2019), Perspective on Pulsed Electric Field Treatment in the Bio-based Industry, Front. Bioeng. Biotechnol. 7:265, doi:

10.3389/fbioe.2019.00265) .

EP-2 308 969 Bl describes a PEF (pulsed electric field) method where a cell material suspended in an electrically conductive liquid, the cell material being positioned between two elec trodes, by exposure of 1 to 100 electric pulses, such that a voltage increase takes place between the two electrodes of 10% to 90% of a target voltage of the electric pulses within a peri od of 0.1 to 100 ns, the electric pulses have a pulse duration of 5 ns to 5000 ns, and the electric pulses, upon reaching the target voltage, have an electric field strength of 0.5 kV/cm to 50 kV/cm, showed an accelerated cell proliferation and/or in creased cell constituents.

In the device for treating cell material used in EP 2308 969 Bl, an electroporation cuvette having the suspension of cell ma- terial described above was continuously pumped through an ar rangement of two electrodes and exposed to an electric field in an electrically conductive liquid (paragraph [0020] of EP-2308 969 Bl).

The arrangement of two electrodes which provide said electric pulses between them can be considered as a plate capacitor. De pending on the kind of medium that is arranged between the elec trodes, the capacity and thus the resistance of said plate ca pacitor varies. As a result, a safe and steady operation cannot be ensured, since the load applied onto the material to be treated varies depending on the electric conductivity of the ma terial.

It was the problem of the present invention to provide a device for treating cells with electric field in a safe, controllable and steady manner.

The above problem was solved with a device according to the pre sent invention.

In detail, the present invention is related to a device, com prising a unit for generating and emitting electric pulses, two or more electrodes or plates of a capacitor that are arranged in one electric circuit with said unit, and a treatment space ar ranged between said electrodes or plates so that the treatment space can be penetrated by the emitted electric pulses and an electric field resulting therefrom, characterized in that at least one additional adjustable resistor is arranged in said electric circuit, and wherein a unit for measuring the electric conductivity of a material to be treated in the treatment space is provided to generate data for automatically adjusting said at least one adjustable resistor. It has been found that when a cell material is brought into the treatment space of the device of the invention, it modifies the electric conductivity, as a material that is brought between the plates of a conventional parallel plate capacitor. As a result, the reactance and thus the impedance of the capacitor in an AC circuit are modified.

In order to ensure safe and controlled application of electric pulses onto the cell material within the treatment space, ac cording to the present invention it has been found that any al teration of conductivity evoked by the cell material in the treatment space has to be compensated by at least one additional resistor to be provided in the electric circuit connecting the unit for generating and emitting electric pulses and the two or more electrodes or plates of a capacitor.

Accordingly, at least one resistor is provided in said electric current that precisely compensates for the modified impedance of the treatment chamber, i.e. the two or more electrodes or plates of a capacitor and the treatment space between them.

Since each cell material may have a different effect on the electric conductivity of the device, according to the present invention the at least one additional resistor is an adjustable resistor (also called variable resistor). Adjustable resistors are generally known in the art. Generally, a variable resistor is a resistor whose electric resistance value can be adjusted. A variable resistor is in essence an electro-mechanical transducer and normally works by sliding a contact (wiper) over a resistive element .

According to a preferred embodiment of the present invention, said at least one adjustable resistor is selected from the group consisting of a potentiometer, a rheostat or a digital potenti ometer.

According to one embodiment of the present invention, said at least one adjustable resistor is in a series connection with re spect to said electrodes or plates. According to the physical laws of electromagnetism, in a series connection the individual resistance values of resistors add up to a total resistance val ue in the electric circuit. In cases where the cell material in the treatment space lowers the impedance of the treatment cham ber, the at least one additional resistor raises the total re sistance value in the electric circuit such that the total re sistance value that would otherwise be present without the cell material in the treatment space is achieved.

According to another embodiment of the present invention, said at least one adjustable resistor is in a parallel connection with respect to said electrodes or plates. According to the physical laws of electromagnetism, in a parallel connection the reciprocal individual resistance values of resistors add up to a total resistance value in the electric circuit. In cases where the cell material in the treatment space increases the impedance of the treatment chamber, the at least one additional resistor lowers the total resistance value in the electric circuit such that the total resistance value that would otherwise be present without the cell material in the treatment space is achieved.

According to the present invention, 1 to 10, preferably 1 to 5 of said adjustable resistors are arranged in said electric cir cuit. The presence of a plurality of adjustable resistors allows an improved fine-tuning of the total resistance value in the electric circuit. Said at least one adjustable resistor should be provided in the electric circuit between said unit for generating and emitting electric pulses and two or more electrodes or plates of a capac itor.

Electric circuits suitable for the present invention are known to the skilled person. A skilled person can adapt such electric circuits in a routine manner, depending on specific needs to be met by the device of the present invention.

By carefully adjusting the resistance value of the at least one adjustable resistor, matched load conditions can be applied onto the treatment space. The device of the present invention pro vides for a safe and controlled treatment in the treatment cham ber, independent from the electric conductivity of the cell ma terial to be treated.

According to the present invention, said adjustment of the re sistance value of said at least one adjustable resistor is per formed automatically.

In each case, the electric conductivity of the material to be treated is determined before the treatment step. This can be done by retrieving the electric conductivity of the material to be treated from known sources, such as literature.

According to the present invention, however, a unit for measur ing the electric conductivity of a material to be treated in the treatment space is provided to generate data for automatically adjusting said at least one adjustable resistor. Such units for measuring the electric conductivity of a material are known in the art and need not be discussed in detail here. Any conven- tional unit for measuring the electric conductivity of a materi al can be used for the purposes of the present invention.

In the case of automatic adjustment of the resistance value of said at least one adjustable resistor, said adjustment is per formed, based on the determined value of the electric conductiv ity of the material to be treated, without interference of user. For example, the unit for measuring the electric conductivity of a material to be treated in the treatment space generates data reflecting the electric conductivity of the material to be treated and transmits them to a component that automatically ad justs the resistance value of said at least one adjustable re sistor (e.g. by moving a slider over a contact or in the case of a digital resistor by electronic signals). Alternatively, known data of an electric conductivity of the material to be treated may be provided as input by a user, e.g. via a user terminal, and processed in the device in a manner similar to the data gen erated by a unit for measuring the electric conductivity.

Devices for electrical treatment of cell material are generally known in the art, e.g. from EP-2 308 969 B1 cited above.

Preferably, a device as described in one of applicant's co pending applications "Device for treating cells", "Non-contact device for treating cells", or "Modified treatment chamber for treating cells" may be used.

Thus, according to one preferred embodiment, a device is used, comprising a unit for generating and emitting electric pulses, a treatment space capable of being penetrated by the emitted elec tric pulses and an electric field resulting therefrom, wherein the device further comprises a unit which can be moved into and out of said treatment space such that cell material provided within a compartment of said unit, or provided in a container on said unit, can be moved into and out of said treatment space.

Thus, by movement of a unit, a compartment in said unit or a container provided on said unit is moved into a certain region of the device, i.e. the treatment space. Once the respective compartment or container has been moved into the treatment space, an electric field acts on the cell material provided in said compartment or container. Preferably, said movement of the unit is a rotational movement. As a result, the cell material is subjected to the electric field from a uniaxial direction, and a homogeneous stimulation of cell growth is achieved.

The cell material or a suspension containing the cell material is passed through an inlet into said compartment or container which is located inside the treatment unit. The inlet is prefer ably connected to a device in which the cell material or a sus pension containing the cell material is located. For example, conventional pipelines can be provided for this connection.

According to the present invention, conventional containers can be used for receiving the cell material. Examples would be bot tles, flasks, test tubes, or cuvettes. Preferably, compartments provided in the unit are of a cylindrical shape. However, also other forms of compartments may be used.

The unit for moving the compartments may be a body, preferably a cylindrical body, which has at least one compartment for receiv ing the cell material and is arranged on a motor for generating a rotational movement. The compartments (preferably 1 to 20, more preferably 2 to 15, even more preferably 5 to 10 compart ments) are preferably blind holes having suitable dimensions. The device may furthermore comprise filling units and emptying units for filling or emptying said compartments.

Alternatively, the unit may be a plate arranged on a motor for generating a rotational movement, on which plate the at least one container can be fastened. Such units are known. To prevent that the container does not fall off the unit during the, pref erably rotational, movement, the unit has means for fastening one or preferably a plurality of containers. Such means are known. They can, for example, be depressions (1 to 20, prefera bly 2 to 15, more preferably 5 to 10) in the surface of the unit or fastening devices provided on the surface of the unit, such as clamps or closures (screw caps, elastic closures, magnetic closures or the like).

According to another embodiment of the present invention, the device comprises a unit for generating and emitting electric pulses, and a treatment unit having an inlet and an outlet, a treatment space being formed inside the treatment unit, the treatment space being able to be penetrated by the emitted elec tric pulses and an electric field resulting therefrom, charac terized in that a cell material entering through the inlet into the treatment space can be moved without contact through the treatment space and the electric pulses penetrating the treat ment space to the outlet.

A non-contact movement (i.e. "without contact") is understood to mean that the material undergoing movement does not come into direct contact with boundary walls (for example, a pipe or a container) during the movement. A non-contact movement according to the present invention is therefore characterized in that there are no interactions (or only very few interactions, pref erably less than 5%, more preferably less than 3% and most pref- erably less than 1% of the material undergoing movement inter acting with boundary walls) with boundary walls during the in teraction and in particular no inhomogeneous flow profile (in the case of the movement of a liquid, suspension or emulsion) is formed.

The cell material or a suspension containing the cell material is passed through the inlet of a treatment unit into a treatment space which is located inside the treatment unit. The inlet of the treatment unit is preferably connected to a device in which the cell material or a suspension containing the cell material is located. For example, conventional pipelines can be provided for this connection.

The inlet may comprise a nozzle or the inlet constitutes a noz zle. It is possible to use nozzles which can conventionally be used for introducing a medium into a container or defined space. Such nozzles are known. With this embodiment, the speed at which the cell material or a suspension containing the cell material is introduced into the treatment unit can be adjusted in a tar geted manner. The residence time of the cell material in the electric field applied to the treatment space of the treatment unit can thereby be adjusted.

The treatment unit can have any geometric shape which allows a non-contact passage of the cell material. Preferably, the treat ment unit is a cylindrical body. This embodiment is character ized by a non-contact passage of the cell material through the treatment space and the electric field penetrating the treatment space to an outlet of the treatment unit. The treatment space therefore has a suitable size to allow the desired non-contact passage of the cell material. According to a preferred embodi ment, the treatment unit is a hollow body, particularly prefera- bly a cylindrical hollow body, the interior of which constitutes the treatment space.

Preferably, the passage of the cell material through the treat ment space takes place under the action of the gravitational force. In this case, the inlet and outlet are to be arranged relative to one another such that the cell material entering through the inlet passes to the outlet through the action of the gravitational force and can escape therefrom out of the treat ment unit. Particularly preferred is an arrangement of inlet and outlet relative to each other such that the outlet is arranged below the inlet, so that the outlet is in the fall line of the inlet. In this case, the inlet is preferably arranged in the top surface, preferably the center of the top surface, of the treat ment unit and the outlet arranged in the bottom, preferably the center of the bottom, of the treatment unit. Particularly pre ferred is thus an arrangement of inlet and outlet relative to each other, in which the outlet is located in the fall line of the inlet. According to the invention, the fall line is the path which a body travels in free fall under the influence of the gravitational force.

Optionally, a receiving device is provided in the treatment unit, with which receiving device the cell material moved through the treatment space can be supplied to the outlet. The receiving device provides an opening which is widened in rela tion to the opening of the outlet, by means of which cell mate rial not moved on an optimally defined path can reliably be guided to the outlet. For this purpose, the receiving device has an upper opening with a larger area and a lower opening with a smaller area, wherein the size of the areas is related to the respective other opening. According to the invention, the re- ceiving device is preferably a funnel-shaped unit having circu lar openings.

Preferably, the treatment space is filled with a dielectric ma terial in order to ensure or improve the penetration of the treatment space with the applied electric field. Preferably, the dielectric material is a gas, more preferably air.

Units for generating and emitting electric pulses are well known. According to the present invention, devices which can generate electrical impulses as described below are preferred. Such devices are known. By way of example, cable pulse genera tors, semiconductor-based pulse generators, or relaxation oscil lators can be mentioned.

The generated electric pulses are emitted in a treatment space. This is preferably done by two or more electrodes or plates of a capacitor arranged parallel to each other, which are arranged opposite each another having a distance suitable for the genera tion of electric pulses. Such arrangements are well known and need not be explained in detail here. Preferably, said two or more electrodes or plates of a capacitor are arranged perpendic ularly to the direction of movement of the unit in or on which the compartment or container is provided. When the compartment or container enters the treatment space, it takes a position in the space between said electrodes or plates, so that one elec trode/plate is provided over said compartment or container, and the other electrode or plate is provided below said compartment or container.

The electric field to be applied to the treatment space must be characterized such that it provides for the desired effect, e.g. that it stimulates the growth of the treated cells. Correspond- ing electric fields are known from the prior art, for example from EP-2308 969 B1. According to the present invention, an electric field generated from such electric pulses can be used, such that a voltage increase takes place between the two elec trodes or plates of a capacitor of the device of 10% to 90% of a target voltage of the electric pulses within a period of 0.1 to 1000 ns, the electric pulses have a pulse duration of 5 ns to 50000 ns, and the electric pulses, upon reaching the target voltage, have an electric field strength of 0.5 kV/cm to 100 kV/cm.

According to another embodiment of the present invention, the device comprises a unit for generating and emitting electric pulses, and a treatment unit having an inlet and an outlet, and a treatment space being formed inside the treatment unit such that it can be penetrated by electric pulses and an electric field resulting therefrom, said treatment space being fluidly connected with the inlet and the outlet, characterized in that at least a portion of an inner side face of the treatment space is curved.

A treatment space is provided within the treatment unit, through which treatment space the cell material passes and is thereby treated with electric pulses.

The treatment space can have any geometric shape, but preferably has a cuboid shape. According to a very preferred embodiment of the present invention, said treatment space is positioned in the centre of the treatment unit. Especially preferred the treat ment unit is a solid body, and the treatment space is a cavity within said treatment unit, preferably in the centre of the treatment unit. The treatment space within the treatment unit is fluidly connected with the inlet and the outlet of the treatment unit.

At least a portion of an inner side face of the treatment space is curved. In other words, the treatment space does not exhibit fully plain inner side faces, but rather at least partially side faces that influence the flow characteristics of the material protruding through the treatment space. Especially preferred, said inner side face of the treatment space has a sinusoidal shape, at least over a portion thereof. According to this embod iment, a preferred design of the treatment space is such that two side surface of the treatment space which lie opposite to each other are curved, and preferably have a sinusoidal shape, over at least 50%, preferably at least 75% and most preferably 100% of their respective heights.

According to the present invention, the device described herein is suitable for medical, environmental, food applications, and bio-based industries (including yeast, lactobacilli, algae, and cell tissue production systems, in particular including targeted inactivation, the extraction of bioactive compounds, and the stimulation of cell growth and/or cellular compounds. These ap plications are described in Buchmann L and Mathys A (2019), Per spective on Pulsed Electric Field Treatment in the Bio-based In dustry, Front. Bioeng. Biotechnol. 7:265, doi: 10.3389/fbioe. 2019.00265. According to the present invention, basically any material composed of at least one cell, that is, both eukaryotic and prokaryotic cells, can be used as the cell material to be treated. The cell material can be unicellular or multicellular organisms of small size (i.e. less than 1 cm diameter). Examples would be bacteria, yeasts, microalgae, plant cells, and fungal cells or their spores, mycelia, seeds or seedlings and somatic animal cells. Furthermore, multicellular tissues such as meri- stems in plants and epithelial or connective tissue in humans or animals can be treated. However, no living animals or humans can be treated with the device of the present invention, due to the technical configuration and the size of the device.

The cell material is usually (but not necessarily) isolated, pu rified and/or sterilized in a known manner before being treated according to the present invention. Preferably, the cell materi al can already be propagated in a known manner in suitable and known culture media to a desired degree before the treatment ac cording to the present invention.

The cell material is preferably suspended in an electrically conductive liquid prior to the treatment according to the pre sent invention. Electrically conductive liquids are well known. According to the present invention, it is necessary to use elec trically conductive liquids which have no adverse effects on cell viability, that is, in particular, are non-toxic. According to the present invention, water is preferably used as the elec trically conductive liquid, wherein the water can be adjusted to a desired pH value by means of suitable and known additives. Ac cording to the present invention, a pH value in the range of 6.0 to 14.0, preferably 7 to 12 is preferred.

According to the present invention, the suspensions described above can be prepared in a conventional manner and stored until treatment. However, the suspensions can also be provided immedi ately before the treatment according to the present invention.

The present invention is furthermore related to a method for treating isolated cell material of unicellular or multicellular organisms, or unicellular or multicellular organisms of a size of less than 1 cm diameter for targeted inactivation, the ex traction of bioactive compounds, and the stimulation of cell growth and/or cellular compounds, performed in a device as de scribed herein, comprising the steps a) introducing cell material into the treatment space, b) applying an electric field to a treatment space, characterized in that the load of said electric field is adjust ed to the cell material to be treated by adjusting at least one adjustable resistor, wherein the step of adjusting said at least one adjustable resistor (9) is carried out before step b) by de termining the electric conductivity of the cell material to be treated and automatically adjusting said at least one adjustable resistor (9) depending on said determined electric conductivity.

The method can be performed as already described above.

As stated above, it is preferred that the cell material is pro vided as a suspension in an electrically conductive liquid in the at least one container.

As stated above, it is further preferred that an electric field is applied with such electric pulses, so that a voltage increase takes place between the two electrodes or plates of a capacitor of the device of 10% to 90% of a target voltage of the electric pulses within a period of 0.1 to 1000 ns, the electric pulses have a pulse duration of 5 ns to 50000 ns, and the electric pulses, upon reaching the target voltage, have an electric field strength of 0.5 kV/cm to 100 kV/cm.

As stated above, according to the present invention, said step of adjusting said at least one adjustable resistor is carried out before step b) by determining the electric conductivity of the cell material to be treated and automatically adjusting said at least one adjustable resistor depending on said determined electric conductivity. As stated above, according to one preferred embodiment of the present invention, said step of determining the electric conduc tivity of the cell material to be treated is carried out by measuring said electric conductivity with a measuring unit.

As stated above, according to one embodiment of the present in vention, the method is preferably carried out as follows. First, the unit is moved such that a respective compartment or contain er in or on said unit is moved into a filling region, where it is filled with cell material through a filling unit. Alterna tively, an already filled container may be provided on said unit. Subsequently, the unit is moved again such that the filled compartment or container enters the treatment space. When the filled compartment or container has been moved into the treat ment space, movement of the unit is stopped for a period of treatment of the cell material that is present in the treatment space. The electric conductivity of the material to be treated is determined either before the material enters the treatment space, or when the material has entered the treatment space, but before the electric field is applied. In any event, the load of the electric field is adjusted to the material to be treated, by adjusting the resistance value of said at least one adjustable resistor, as described above.

After the treatment has been performed, the filled compartment or container is moved, by movement of the unit, into an emptying region where the treated cell material is removed from the filled compartment or container, as described above. Alterna tively, a filled container can be removed from the unit alto gether. The empty container or compartment can be subsequently moved again into the filling region, to start another treatment cycle. Optionally, a sterilization/sanitization step may be per formed prior to the start of another treatment cycle. Known sterilization/ sanitization processes such as steam-based pro cesses can be used in accordance with the present invention.

According to another embodiment of the present invention, it is preferred that a non-contact passage of the cell material through the treatment space is performed, and the electric field penetrating the treatment space to an outlet of the treatment unit takes place due to gravitational force.

The present invention further relates to the use of the device according to the present invention described here for medical, environmental, food applications, and bio-based industries (in cluding yeast, lactobacilli, algae, and cell tissue production systems, in particular including targeted inactivation, the ex traction of bioactive compounds, and the stimulation of cell growth and/or cellular compounds. These applications are de scribed in Buchmann L and Mathys A (2019), Perspective on Pulsed Electric Field Treatment in the Bio-based Industry, Front. Bio- eng. Biotechnol. 7:265, doi: 10.3389/fbioe.2019.00265.

The present invention is explained below by way of non-limiting examples and figures. Shown are:

Fig. 1 a schematic representation of a first embodiment of the device of the present invention Fig. 2 a schematic representation of a second embodiment of the device of the present invention Fig. 3 a schematic representation of a third embodiment of the device of the present invention Fig. 4a-c a schematic representation of a fourth embodiment of the device of the present invention

Fig. 5 a schematic illustration of an electric circuit accord ing to a first example of the present invention Fig. 6 a schematic illustration of an electric circuit accord ing to a second example of the present invention Fig. 7 a schematic illustration of an electric circuit accord ing to a third example of the present invention Fig. 8 a schematic illustration of an electric circuit accord ing to a fourth example of the present invention

Fig. 1 shows a schematic representation of an embodiment of the device (1) of the present invention.

The device has a unit (2) for generating and emitting electric pulses, for example, a pulse generator. The unit (2) is electri cally connected to two electrodes (2a, 2b). A treatment space (3) is located between and closed by the electrodes (2a, 2b), on which treatment space (3) an electric field generated by the unit (2) is applied. The electrodes (2a, 2b) are arranged per pendicularly to the direction of movement of the unit (4). When the compartment (4a) enters the treatment space (3), it takes a position in the space between said electrodes (2a, 2b), so that one electrode (2a) is provided over said compartment (4a), and the other electrode (2b) is provided below said compartment (4a).

A rotatable unit (4) is provided in the device (1). In the em bodiment according to Fig. 1, this unit (4) is a cylindrical body, which by way of example here has 4 compartments (4a) for receiving cell materials. The compartments (4a) are blind holes of suitable dimension.

The rotatable unit (4) is arranged on a motor (6) which gener ates a rotational movement and sets the unit (4) arranged on it into rotary movement. The compartments (4a) also undergo a rota tional movement in this way. Preferably, the unit (4) is rotated at least once around an imaginary axis defined through the cen ter of the unit (4), whereby the compartments (4a) undergo a ro tation of 360°. A multiple complete rotation of the unit (4) is possible and advantageous depending on the cell material to be treated .

An adjustable resistor (9) is provided between the unit (2) and the electrode/plate (2a). Fig. 1 only shows a schematic illus tration of the presence of the adjustable resistor (9). Refer ence is made to Figs. 4 to 7 for examples of suitable electric circuit arrangements. The adjustable resistor (9) is connected to a unit (13) for measuring the electric conductivity of the material to be treated. Said unit (13) is only shown schemati cally. It can be located at an appropriate position in the de vice (1) for measuring the electric conductivity of the material before said material is moved into the treatment space (3).

In a region of the device (1) preceding the treatment space (3) in the direction of movement of the unit (4), a compartment (4a) is filled with cell material by means of a filling unit (7).

The filling unit (7) is connected to a device (not shown) in which the cell material or a suspension containing the cell ma terial is located.

The filling region is arranged such that the compartment (4a) is first moved into the filling region, where the compartment (4a) is filled to a desired volume (during which time the compartment (4a) remains in a filling position relative to the filling unit (7)), and subsequently the unit (4) is moved further such that the filled compartment (4a) is transferred into the treatment space (3). Subsequently, the filled compartment (4a) is transported into the treatment space (3), by means of movement of the unit (4). Therein, the cell material in the compartment (4a) undergoes the desired treatment, after the electric field has been adequately adjusted by adjusting the adjustable resistor (9).

After treatment, the cell material is removed from the compart ment (4a) by means of an emptying unit (8). In the embodiment of Fig. 1, the emptying unit (8) is a pipeline having an inlet in an emptying region. When the at least one compartment (4a) filled with the treated cell material, after treatment in the treatment space (3), is moved into the emptying region, by means of movement of the unit (4), the compartment (4a) can be con nected with the inlet of the emptying unit (8).

The empty compartment (4a) can be subsequently moved again into the filling region, to start another treatment cycle.

Fig. 2 shows a schematic representation of a second embodiment of the device (1) of the present invention. Like reference nu merals designate the same components as in Fig. 1.

In this embodiment, a unit (4) in the form of a plate is provid ed. Said unit (4) comprises recesses in which one or more con tainers (5) can be securely arranged so as to not fall off dur ing movement of the unit (4). In the embodiment according to Fig. 2, the unit (4) comprises 4 recesses and thus can take up 4 containers (5).

An adjustable resistor (9) is provided between the unit (2) and the electrode/plate (2a). Fig. 2 only shows a schematic illus tration of the presence of the adjustable resistor (9). Refer ence is made to Figs. 4 to 7 for examples of suitable electric circuit arrangements. The adjustable resistor (9) is connected to a unit (13) for measuring the electric conductivity of the material to be treated. Said unit (13) is only shown schemati cally. It can be located at an appropriate position in the de vice (1) for measuring the electric conductivity of the material before said material is moved into the treatment space (3).

Similar to the embodiment according to Fig. 1, in a region of the device (1) preceding the treatment space (3) in the direc tion of movement of the unit (4), a container (5) is filled with cell material by means of a filling unit (7).

The filling unit (7) is connected to a device (not shown) in which the cell material or a suspension containing the cell ma terial is located.

The filling region is arranged such that the container (5) is first moved into the filling region, where the container (5) is filled to a desired volume (during which time the container (5) remains in a filling position relative to the filling unit (7)), and subsequently the unit (4) is moved further such that the filled container (5) is transferred into the treatment space (3).

Alternatively, instead of filling a container (5) in the filling region, also a filled container (5) may be put (manually or au tomatically) into a free recess on the unit (4).

Subsequently, the filled container (5) is transported into the treatment space (3), by means of movement of the unit (4). Therein, the cell material in the container (5) undergoes the desired treatment, after the electric field has been adequately adjusted by adjusting the adjustable resistor (9). After treatment, the cell material is removed from the container (5) by means of an emptying unit (8). In the embodiment of Fig. 2, the emptying unit (8) is a pipeline having an inlet in an emptying region. When the at least one container (5) filled with the treated cell material, after treatment in the treatment space (3), is moved into the emptying region, by means of move ment of the unit (4), the container (5) can be connected with the inlet of the emptying unit (8).

Alternatively, instead of emptying a container (5) in the empty ing region, also a filled container (5) may be removed (manually or automatically) from the unit (4) altogether.

The empty container (5) can be subsequently moved again into the filling region, to start another treatment cycle. Alternatively, an empty or filled container (5) may be put into a free recess on the unit (4).

Fig. 3 shows a schematic representation of a further embodiment of the device (1) of the present invention for treating cells for stimulating cell growth.

The device has a unit (2) for generating and emitting electric pulses, for example, a pulse generator. The unit (2) is electri cally connected to two electrodes (2a, 2b). A (here cylindrical) treatment unit (10) having a treatment space (3) in its interior is located between the two electrodes (2a, 2b), to which treat ment space an electric field generated by the unit (2) is ap plied, after the electric field has been adequately adjusted by adjusting the adjustable resistor (9).

An adjustable resistor (9) is provided between the unit (2) and the electrode/plate (2b). Fig. 3 only shows a schematic illus- tration of the presence of the adjustable resistor (9). Refer ence is made to Figs. 4 to 7 for examples of suitable electric circuit arrangements. The adjustable resistor (9) is connected to a unit (13) for measuring the electric conductivity of the material to be treated. Said unit (13) is only shown schemati cally. It can be located at an appropriate position in the de vice (1) for measuring the electric conductivity of the material before said material is moved into the treatment space (3).

An inlet (10a) is arranged on the top surface of the treatment unit (10) according to this embodiment, preferably in the center of the top surface of the treatment unit (10). An outlet (10b) is arranged on the bottom surface of the treatment unit (10) ac cording to this embodiment, preferably in the center of the bot tom surface of the treatment unit (10). According to this embod iment, the outlet (10b) is arranged in the fall line of a cell material which enters into the treatment unit (10) through the inlet (10a) and passes through the treatment space (3) due to gravitational force.

A (here funnel-shaped) receiving device (11) is arranged in the treatment space (3). The receiving device (11) is arranged ac cording to the embodiment shown here in the treatment space (3) immediately above the outlet (10b), so that the lower opening of the receiving device (11) is arranged flush with the (not shown here) opening of the outlet (10b). According to the embodiment shown here, the lower opening of the receiving device (11) and the opening of the outlet (10b) have the same area.

Fig. 4a shows a schematic representation of a further embodiment of the device (1) of the present invention. The device has a unit (2) for generating and emitting electric pulses, for example, a pulse generator. The unit (2) is electri cally connected to two electrodes (2a, 2b). A treatment unit (10) is located between the electrodes (2a, 2b). On a treatment space (3) within said treatment unit (10) (see Fig. 4b and c), electric pulses generated by the unit (2) are applied. The elec trodes (2a, 2b) are arranged perpendicularly to the direction of movement of material moving through the treatment unit (10). The material enters the treatment unit (10) through an inlet (10a) in the top face of the treatment unit (10), and leaves the treatment unit (10) through an outlet (10b) in the bottom face of the treatment unit (10).

In two side faces of the treatment unit (10), there are provided openings (12a, 12b), preferably in the form of blind bores, into which the electrodes (2a, 2b) may be inserted and secured.

In Fig 4b, the embodiment of Fig. 4a is shown wherein the treat ment unit (10) is a solid body with a treatment space (3) in the form of a cavity in its center. The inlet (10a) in the top face of the treatment unit (10) is fluidly connected, by means of a conduit, with the treatment space (3). In this embodiment, the fluid connection is funnel-shaped over it lower part discharging into the treatment space (3). The outlet (10b) in the bottom face of the treatment unit (10) is also fluidly connected, by means of a conduit, with the treatment space (3). In this embod iment, the fluid connection is funnel-shaped over it upper part extending from the treatment space (3). In two side faces of the treatment unit (10), there are provided openings (12a, 12b) in the form of blind bores for insertion of electrodes. These open ings are tapered in a region adjacent to the treatment space (3), i.e. they become smaller as they approach the treatment space (3). The side faces of the treatment space (3) adjacent to the openings (12a, 12b) are plain, i.e. they are not curved.

Fig. 4c is another schematic representation of the treatment unit (3) of the embodiment of the device (1) according to Fig. 4a. As compared to Fig. 4b, the treatment unit (10) is turned by 90°. Thus, in Fig. 4c the side faces of the treatment space (3) are shown that are not adjacent to the openings (12a, 12b).

These side faces are curved. Here, they have a sinusoidal shape over their entire height.

Fig. 5 shows one example of an electric circuit arrangement suitable for the present invention, for example in connection with any of the embodiments shown in Figs. 1 to 4a-c above.

In this example, between a unit (2) for generating and emitting electric pulses and a treatment space (3) in which a material is to be treated by an electric field, there is provided an adjust able resistor (9). In this example, the adjustable resistor (9) and the treatment space (3), respectively the electrodes or plates (2a, 2b) around the treatment space (3), are connected in series. The adjustable resistor (9) is connected to a unit (13) for measuring the electric conductivity of the material to be treated. Said unit (13) is only shown schematically. It can be located at an appropriate position in the device (1) for measur ing the electric conductivity of the material before said mate rial is moved into the treatment space (3).

Fig. 6 shows another example of an electric circuit arrangement suitable for the present invention, for example in connection with any of the embodiments shown in Figs. 1 to 4a-c above. In this example, after a unit (2) for generating and emitting electric pulses, a treatment space (3) in which a material is to be treated by an electric field and an adjustable resistor (9) are provided in a parallel connection. The adjustable resistor (9) is connected to a unit (13) for measuring the electric con ductivity of the material to be treated. Said unit (13) is only shown schematically. It can be located at an appropriate posi tion in the device (1) for measuring the electric conductivity of the material before said material is moved into the treatment space (3).

Fig. 7 shows another example of an electric circuit arrangement suitable for the present invention, for example in connection with any of the embodiments shown in Figs. 1 to 4a-c above.

In this example, between a unit (2) for generating and emitting electric pulses and a treatment space (3) in which a material is to be treated by an electric field, there is provided an adjust able resistor (9). In this example, two adjustable resistors (9) are provided in a parallel connection, and these two resistors (9) and the treatment space (3), respectively the electrodes or plates (2a, 2b) around the treatment space (3), are connected in series. The adjustable resistor (9) is connected to a unit (13) for measuring the electric conductivity of the material to be treated. Said unit (13) is only shown schematically. It can be located at an appropriate position in the device (1) for measur ing the electric conductivity of the material before said mate rial is moved into the treatment space (3).

Fig. 8 shows another example of an electric circuit arrangement suitable for the present invention, for example in connection with any of the embodiments shown in Figs. 1 to 4a-c above. In this example, after a unit (2) for generating and emitting electric pulses, a treatment space (3) in which a material is to be treated by an electric field and three adjustable resistors (9) are provided in a parallel connection. The three adjustable resistors (9) are arranged such that a pair of serially connect ed adjustable resistors (9) is connected in series to a preced ing adjustable resistor (9). The adjustable resistors (9) are connected to a unit (13) for measuring the electric conductivity of the material to be treated. Said unit (13) is only shown schematically. It can be located at an appropriate position in the device (1) for measuring the electric conductivity of the material before said material is moved into the treatment space (3).