EP3784375A1

EP3784375A1 - Diluting, mixing and/or aliquoting two fluids in a microfluidic system

Info

Publication number: EP3784375A1
Application number: EP19717285.1A
Authority: EP
Inventors: Jochen Hoffmann; Tino Frank
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-04-26
Filing date: 2019-04-09
Publication date: 2021-03-03
Also published as: DE102018206463A1; WO2019206616A1; US20210170349A1; CN111989153A

Abstract

The invention relates to a method for diluting, mixing and/or aliquoting two fluids (F1, F2) using a microfluidic system, comprising at least two pump chambers (1, 2) which are interconnected by at least one microfluidic channel (3). The at least one channel (3) is designed such that at least some of the first fluid (F1) remains in the channel (3) after the pumping action. The method comprises the following steps: to begin with, at least one of the pump chambers (1) is filled with a first fluid (F1), the first fluid (F1) is then pumped through the channel (3), some of the first fluid (F1) remaining in the channel (3). The portion of the first fluid (F1) that remains in the channel (3) is then ascertained. Finally, the channel (3) is flushed using a second fluid (F2).

Description

description

DILUTING, MIXING AND / OR ALIQUOTING TWO LIQUIDS IN A MICROFLUIDIC SYSTEM

The present invention relates to a method of dilution, mixing

and / or aliquoting two fluids in a microfluidic system having at least two sample chambers and at least one channel.

State of the art

For various applications, microfluidic devices or systems, such as microfluidic chips, are used. Such, usually made of plastic, fluidic devices can

For example, for analytical, preparative or diagnostic applications, especially in medicine, are used and are used for the analysis of

Sample solutions with high sensitivity in miniaturized form. The

Microfluidic systems allow automation and parallelization of the executed process steps. The microfluidic systems can

be used for example in the form of a so-called lab-on-chip system, the functionalities of a laboratory in a sense in the

Bank card format are summarized. Through the miniaturization

The laboratory processes can be carried out directly at the point of care at the treatment site (point-of-care).

In order to be able to carry out various processes, it is often intended to dilute, mix and / or aliquot liquids and divide them into different volumes. Conventionally, the

Dilution, mixing and / or aliquoting d. H. the proportionate

Determination, by means of a fixed geometry of the microfluidic system

realized. Disclosure of the invention

The invention also relates to a method for diluting, mixing and / or aliquoting two liquids using a microfluidic system comprising at least two pumping chambers interconnected by at least one microfluidic channel (hereinafter referred to as "channel" for short). The pumping chambers each have an inlet and a drain, via which the pumping chambers can be filled or emptied with liquid, wherein the outlet of the one pumping chamber is connected via the microfluidic channel to the inlet of a further pumping chamber. At least one of the pumping chambers is arranged to pump a first fluid, with which this chamber has been filled, through the at least one channel into another chamber. For this purpose, the pumping chamber (hereinafter referred to as "chamber" called) have a membrane which is deflected during pumping and displaces the liquid from the chamber. The first liquid is in particular an aqueous solution with an analyte to be examined.

In a first step, at least one of the chambers is filled with a first liquid. The first liquid is in particular a sample solution to be investigated. Subsequently, the first liquid is pumped through the channel to another chamber. Due to the design of the channel, a part of the first liquid remains in the channel. Preferably, the channel is completely filled with the first liquid after pumping. The remaining part of the first liquid in the channel is dependent on the design of the channel, in particular its geometry, shape and length. By choosing the channel, the volume of the part of the first liquid remaining in the channel can be specified. The part of the first liquid remaining in the channel becomes

subsequently determined. This determination can be realized purely in principle by additional components. However, the known geometry, shape and length of the channel are preferably used for this purpose, and from this the volume of the part of the first liquid remaining in the channel

closed.

The same channel, in which the part of the first liquid is located, is flushed with a second liquid, so that the first liquid and the second liquid mix. (Rinse) means in this context, that the second liquid flows through the microfluidic system and in particular through the channel. In this case, the second liquid can be kept in one of the other chambers and then pumped into the system. For this purpose, closed circuits are particularly suitable in which the sequence of each of the chambers is connected to an inlet of one of the further chamber. This is called cyclic mixing. This means that mixing of the two liquids can be achieved by alternately pumping between the two chambers. Alternatively, the second fluid can be supplied from the outside via an inlet to the microfluidic system. For this purpose, an external device, for example an external pump, can be used which is outside the described

Microfluidic system is arranged. The volume of the purged second liquid can be adjusted. In particular, the second liquid is also an aqueous solution. As a result, mixing and / or dilution of the two liquids with a defined and controllable volume of the first liquid and a volume of the second liquid which can be set during rinsing can be realized in a simple manner. Optionally, you can then continue to aliquot, i. H. a pro-rata determination to be made of the mixture. Thus, a particularly simple passive separation or removal of a partial volume of the first fluid from the total volume can be realized. It is particularly advantageous that the dynamic mixture allows adjustment of the reaction mixture and / or the dilution stage during the experiment. This allows the

Dilution stage can be selected depending on the initially existing total volume of the first liquid.

The method may also be used for a microfluidic network formed of a plurality of pumping chambers and a plurality of channels through which the chambers are interconnected. For this purpose, the above steps can be repeated. The above described two pumping chambers and the channel connecting the two may be considered as a module of the microfluidic network. The microfluidic network describes a superordinate structure of the

Pump chambers and the channels and can be considered part of the microfluidic

Systems are viewed. According to the present aspect, the microfluidic network comprises a plurality of the modules described above. The individual modules can be designed differently and

in particular have different configured channels in which then remain different sized volumes of the first liquid. This makes it possible to produce different mixing ratios and / or dilution stages in a given microfluidic network. This has the advantage that desired dilutions can be produced in a defined manner. The microfluidic network can also have other modules, chambers and / or channels. The modules described above can be incorporated into existing microfluidic networks.

The terms "first" liquid and "second" liquid should only serve to distinguish the two liquids. At each repetition of the process, the same or different liquids can be chosen as new "first" or "second" liquids and the invention is not limited to two types of liquids. Depending on the application, the first liquid with which at least one of the chambers is filled is selected according to the following options: Firstly, the first liquid corresponds to the initial first liquid which has been transferred by pumping into this chamber (s) minus the part of the first liquid which remained in the canal.

On the other hand, the mixture of the first liquid with the second

Liquid produced after one pass of the process will be considered a new first liquid when the process is repeated. As a result, further mixtures or dilutions can be achieved. In both ways, in repeating the process, the second liquid may correspond to the initial second liquid or another second liquid may be selected. In addition, when repeating the process, another channel can be selected through which the first liquid is pumped. As already described, the channels may be different and thus have a different volume in the

remain different channels. By choosing the channel different mixing ratios or dilution levels can be achieved.

It is mainly surface effects of the first liquid and of the channel that cause the part of the first liquid to remain in the channel after pumping. The main effects here are the surface tension of the (first) liquid itself and the interfacial tension between the (first) liquid and to call the (first) liquid in contact surface of the channel. The surface effects preferably lead to a capillary effect of the (first) liquid in the channel. The mentioned

Surface effects depend on the geometry, shape and length of the channel, the material of the surface of the channel, and the fluid itself. In terms of surface effects, the aqueous first fluid can be equated with water, making it easy to handle.

According to the present aspect, the at least one channel is configured such that the desired part of the liquid remains in the channel after pumping due to the surface effects. Preferably, the ratio between the volume of the pumping chamber, therefore the chamber from which the first liquid is pumped into the connecting channel, and the volume of the channel is in a range between 1: 2 and 1: 10,000, more preferably in a range between 1: 5 and 1: 1000. These ratios are particularly well suited for leaving some of the first liquid in the channel. The volume of the pumping chamber is preferably in a range between 1 pl and 500 pl, more preferably in a range between 10 ml and 50 ml. These volumes of the pumping chambers are particularly well suited for typical investigations, for example in molecular diagnostics.

As already described, the part of the first liquid remaining in the channel is determined. For this purpose, on the one hand, the volume of the channel from the known geometry, shape and length of the channel can be calculated and deduced therefrom to the volume of remaining in the channel portion of the first liquid. In the case of a complete filling of the channel with the first liquid, the volume of the part of the first liquid remaining in the channel corresponds exactly to the volume of the channel. The volume of the channel is usually known, for example predetermined during production or determined by measurement, which is why in this case the volume of the channel and the volume of the part of the first liquid remaining in the channel,

be equated. Alternatively, a camera can be used together with the evaluation unit, in order to determine the volume of the remaining part of the first liquid in the channel, taking into account the geometry, shape and length of the channel, for which purpose the degree of filling can be determined. In addition, the dilution stage of the liquid can be determined with the aid of the camera described above together with the evaluation unit. The determined data, therefore, the volume and / or mass of the portion of the first liquid may be used to monitor the achievement of a desired mixing ratio and / or dilution level. Alternatively or additionally, the determined data may be used to determine the volume of the second liquid needed to produce the desired one

Dilution, mixing and / or aliquoting.

In one aspect, the chambers are deflated after the pumping chamber has pumped the first liquid into the other chamber. It is provided that the first liquid is also after the chambers have been emptied, remains in the at least one channel. Subsequently, the second liquid can be introduced through the now empty chambers in the microfluidic system. This makes it particularly easy to realize the mixture or the dilution of the first liquid with the second liquid. After emptying, only the first liquid remaining in the channel, the volume of which is known, is present in the microfluidic system. In other words, during rinsing, the second liquid can only mix with the known first liquid in the channel, since after emptying and before rinsing, no further liquid is present in the considered microfluidic system. It should be noted here that, in connection with a microfluidic network described above, not all the pumping chambers need to be emptied simultaneously and, nevertheless, further fluid may be present in the microfluidic network - also outside the channels, in particular also in the chambers.

The computer program is set up to perform each step of the method, in particular when it is performed on a computing device or controller. It allows the implementation of the method in a conventional electronic control unit without having to make any structural changes. For this it is on the machine-readable

Storage medium stored.

By putting the computer program on a conventional

Electronic control unit for controlling the microfluidic system, the electronic control unit is achieved, which is set up using of the microfluidic system to dilute, mix and / or aliquot the two fluids.

The electronic control unit may be part of a lab-on-chip, also called chip laboratory, comprising the above-described microfluidic system. The lab-on-chip also includes components for controlling fluid flow, components for performing laboratory processes, and

Components for evaluation in a compact design. This integrated design allows a sample solution to be fully tested in a lab-on-chip. Optionally, the lab-on-chip, a camera, which detects the at least one channel, and an evaluation, which evaluates signals from the camera. The camera detects the liquid in the channel and, for example, records the fluorescence and / or the turbidity of the liquid and forwards its signals to the evaluation unit. The evaluation unit determines from the camera signals, i. H. for example, from the fluorescence and / or the turbidity of the dilution stage of the liquid. Thereby, the achievement of the desired mixing ratio and / or the desired dilution stage can be monitored. By monitoring the

Dilution stage is a feedback system (feedback system) given, over which the mixing or dilution of the liquid (s) can be controlled or regulated. In addition, the evaluation unit can also determine the volume of the remaining part of the first liquid in the channel.

Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

Figures 1 a-d show schematic representations of a first embodiment of the invention.

Figures 2 a-f show schematic representations of a second embodiment of the invention.

Figures 3 ai show schematic representations of a third embodiment of the invention. Figures 4 ag show schematic representations of a fourth embodiment of the invention.

FIG. 5 shows a schematic representation of a lab-on chip on which an embodiment of the method according to the invention can proceed.

Embodiments of the invention

Figures 1 a-d show schematic representations of a microfluidic system. The basic concept of the microfluidic system will be explained below, which serves as an independent module for use in a

Microfluidic network can be considered. The subfigures 1 ac each represent a step of a first embodiment of the method according to the invention. The microfluidic system has a first pumping chamber 1 and a second pumping chamber 2, which are both of the same design in this embodiment and each have a membrane, not shown, which during pumping is deflected and displaced a liquid from the respective chamber. In further embodiments, the first

Pumping chamber 1 and the second pumping chamber in structure, function, volume and the components included differ. The two chambers 1, 2 are interconnected via a microfluidic channel 3, wherein the microfluidic channel 3 connects an outlet 11 of the first chamber 1 with an inlet 20 of the second chamber 2. The volume of the pumping chambers 1, 2 is

For example, 30 pl and the ratio between the volume of

Pumping chambers 1, 2 and the volume of the channel is 1: 100. In FIG. 1a, the first chamber 1 has been filled via its inlet 10 with a first liquid Fi, which has an analyte to be examined and is based on water. The second chamber 2 and the channel 3 are filled with a second liquid F ₂ .

In FIG. 1 b, the membrane of the first chamber 1 is deflected and thereby the first liquid Fi is pumped through the channel 3 into the second chamber 2, thereby displacing the second liquid F ₂ from the second chamber 2 and the channel 3. The channel 3 is designed such that at least a portion of the first liquid Fi remains in the channel 3 after pumping. In particular, surface effects, such. B. the surface tension of the first liquid Fi itself and the interfacial tension between the first liquid Fi and the surface of the channel 3 in contact with the first liquid Fi, on the first liquid Fi and lead to a capillary effect of the first liquid Fi in the channel 3, whereby it is retained in the channel 3. The surface effects mentioned are dependent on the geometry, shape and length of the channel 3, the material of the surface of the channel 3 and the liquid Fi itself. In this embodiment, the channel 3 is completely filled with the first liquid Fi after pumping.

In FIG. 1c, the second chamber 2 is emptied via its outlet 21, the first liquid Fi remaining in the channel 3, even after emptying, owing to the design of the channel 3 and the effective surface effects. Subsequently, a second liquid F ₂ , with which the first liquid Fi is to be mixed or diluted, introduced via the inlet 10 of the first chamber 1 in the microfluidic system and rinsed through the channel 3. In Figure ld, the first liquid Fi and the second liquid F ₂ mix to form a first mixture Mi and the first liquid Fi is diluted with the second liquid F ₂ . Since the geometry, shape and length of the channel 3 is known and this was completely filled with the first liquid Fi, it can be used to determine the volume of the first liquid, so that the mixing ratio or the dilution stage can be controlled. In addition, the aliquoting, ie a proportional determination of the first liquid Fi or of the analyte, is provided.

For reasons of clarity, FIGS. 1-4 do not show valves for controlling the fluid flow. In the following, the same components are identified by the same reference numerals, so that their repeated description is omitted. The terms "first chamber" and "second chamber" refer to their filling with a first liquid Fi and / or a second liquid F ₂ . Within the subfigures, reference symbols of solid components are only entered for the respective subfigures a for a better overview and can be transferred to the further subfigures.

Figures 2 af show schematic representations of a microfluidic system in which the outlet 11 of the first chamber 1 and the outlet 21 of the second chamber 2 are connected via a microfluidic channel 3 and the inlet 10 of the first chamber 1 and the inlet 20 of the second chamber 2 via a further microfluidic channel 3 ', which is formed in analogy to the microfluidic channel 3, so that the microfluidic System forms a closed microfluidic circuit. The channel 3 is connected to a common outlet 30. Via the inlets 10, 20 and the common outlet 30, the module described above can be incorporated into a microfluidic network. The chambers 1, 2, inlets 10, 20 and the common outlet 30 can be controlled individually.

The subfigures 2 af each represent a step of a second embodiment of the method according to the invention. In FIG. 2 a, the first chamber 1 is filled with a first liquid Fi and a second liquid F _{2 is} held in the second chamber 2. In Figure 2b, the first liquid Fi is pumped out of the first chamber 1 into the channel 3 'and out through the outlet 30. As described above, part of the first liquid Fi remains in the channel 3. In Figure 2c, the two chambers 1, 2 are alternately opened and closed under pumping, so that the second liquid F ₂ moves through the channels 3, 3 'in a closed circuit and with the first liquid Fi, which has remained in the channel 3, mixed. This process is called cyclic mixing. After a defined number of cycles, the two liquids Fi and F ₂ , as shown in Figure 2d, completely mixed to a mixture Mi with a defined mixing ratio and the chambers 1, 2 are closed. The mixture Mi can now be used for further investigation purposes. FIGS. 2e and 2f show how a further mixture M ₂ having a different mixing ratio is produced from the mixture Mi. Similar to the first liquid Fi, a part of the first mixture Mi remains in the channels 3, 3 '. The second chamber 2 is filled via the inlet 20 again with the second liquid F ₂ . In other embodiments, depending on the desired mixing ratio, instead the first chamber 1 may be filled with the second liquid F ₂ or either the first chamber 1 or the second chamber 2 may be filled with the first liquid Fi. Subsequently, the cyclic mixture of the second liquid F ₂ with the first mixture Mi, which was completely mixed after a defined number of cycles in FIG. 2f to form the second mixture M ₂ , takes place again. FIGS. 3 ai show schematic representations of a microfluidic network, with which dilution series with different

Have dilution stages and mixing ratios realized. The outlet of the first chamber 1 is connected via the microfluidic channel 3 simultaneously with the inlet 20 of the second chamber 2 and an inlet 40 of a third chamber 4. The outlet 21 of the second chamber 2 is connected to an outlet 41 of the third chamber 4 via a further microfluidic channel 3 ', which is designed analogously to the microfluidic channel 3. The further channel 3 'has a common outlet 30, which branches several times and thus forms a network. Each branch of the common outlet 30 and the chambers 1, 2, 4 can be individually controlled by means of the valves described above. At the marked with reference numeral 31 point of the common outlet 30, a bypass not shown is arranged. At least the common outlet 30 can be flushed out via this bypass.

The subfigures 3 ai each represent a step of a third embodiment of the method according to the invention. In FIG. 3 a, the first chamber 1 is filled with the first liquid Fi, which in FIG. 1b is pumped through the channel 3 into the third chamber 4, one part the first liquid Fi remains in the channel. The chamber 1 is filled with the second liquid F ₂ and this then, as shown in Figure 3c, pumped into the second chamber 2, in which case a part of the second liquid F ₂ remains in the channel. In FIG. 3d, the second liquid F ₂ is cyclically mixed with the first liquid Fi, as already explained in connection with FIG

Mixture Mi with a defined mixing ratio and a defined

Dilution level is obtained. As shown in Figure 3e, the first mixture Mi is diverted through the outlet 30 into one of the branches and may then continue to be used. Subsequently, the common outlet 30 is flushed via the above-mentioned bypass, so that the first mixture Mi is removed from the common outlet 30 to a negligibly small part. Several steps are summarized in FIG. 3f. It remains a part of the first mixture Mi in the channel 3 ', which is then pumped into the second chamber 2. In addition, the first chamber 1 is again filled with the first liquid Fi in analogy to FIG. 3a, and the first liquid Fi is then filled in analogy with FIG. 3b again pumped into the third chamber 4. Depending on the desired mixing ratio and the dilution stage can in further

Embodiments, the second liquid F ₂ may be used instead. In FIG. 3g, a cyclic mixing of the first mixture Mi with the first liquid Fi takes place again in order to obtain a second mixture M ₂ . This second mixture M ₂ is then discharged through the outlet 30 into a further branch, as shown in FIG. 3 h. The above steps are repeated to obtain the dilution series of eight shown in FIG

different mixtures Mi, ... Me to receive, each one

have different mixing ratio and different dilution levels.

FIGS. 4 a-g show schematic representations of a microfluidic system for performing a nested PCR (nested polymerase chain reaction). Here is a pre-amplificate on two different

Reaction strands are divided and primers of pre-amplification are diluted so much that they are no longer active in a second PCR. The already described first chamber 1 and second chamber 2 are each assigned a further chamber 5, 6, in which lyophilisates L, also called lyobeads, are present. The chambers 1, 2, 5, 6 are interconnected via microfluidic channels 3. In this case, the first chamber 1 and the second chamber 2 together form a cycle. Furthermore, the first chamber 1 with its associated chamber 5 and the second chamber 2 with its associated chamber 6 each form a sub-circuit. In order to realize a so-called shuttle PCR, the first chamber 1 and the second chamber 2 may be assigned further chambers (not shown) in further exemplary embodiments, so that in each case three chambers form one unit.

The partial figures 4 a-g each represent a step of a fourth embodiment of the method according to the invention. At the beginning, in FIG. 4 a, the first chamber 1 is filled with the reaction product of a pre-amplification as the first liquid Fi. The first liquid Fi is then pumped through the circuit between the first chamber 1 and the second chamber 2 in FIG. 4b. In this case, a part of the first liquid Fi remains in the channel 3.

Subsequently, the microfluidic system is rinsed with an aqueous second liquid F ₂ , as shown in Figure 4c. The first liquid Fi, ie the pre-amplificate, and the second liquid F ₂ , ie the buffer, are then, as shown in FIG. 4 d, mixed by circulation pumping the first chamber 1 and the second chamber 2, so that a mixture Mi is formed. The

Dilution step can be adjusted by repeating the steps as described in connection with FIG. Was the desired

Reached dilution stage, the mixture Mi is pumped into the chambers 5 and 6 - see Figure 4e. By pumping the mixture Mi in the subcircuit between the first chamber 1 and the associated chamber 5 and in

Subcirculation between the second chamber 2 and the associated chamber 6, the therein contained lyophilisate L are dissolved in the mixture Mi - see Figure 4f. The resulting mixed product is then, as shown in Figure 4g, pumped into the first chamber 1 and in the second chamber. Subsequently, the second, specific PCR is started.

FIG. 5 shows a schematic representation of a lab-on-chip with a feedback system (feedback system) on which an embodiment of the method according to the invention can proceed. The microfluidic system S is detected by a camera 7, which records the fluorescence and / or the turbidity of the liquid. In addition, an evaluation unit 8 is provided, which receives the camera signals. The evaluation unit 8 determines from the

Camera signals algorithmically the dilution stage and / or the

Mixing ratio of the liquids Fi, F ₂ . The above-described steps for changing the dilution stage are repeated until the desired dilution or the desired mixing ratio has been achieved and has been recognized by the evaluation unit 8. Then, the evaluation unit 7, a release signal to a pneumatic control unit 9 on which controls the microfluidic system S and initiates further steps, such. B. the forwarding of the resulting mixture. In addition, the determined

Evaluation unit 8, the volume of the second liquid F ₂ required for the desired dilution, mixing and / or aliquoting. On the one hand, the evaluation unit 8 can calibrate the dilution stage with previously calibrated

Compare dilution levels. Secondly, the evaluation unit 8 can be calibrated during the examination. The volume of the remaining part of the first liquid Fi in the channel 3 is determined from the geometry, the shape and the length of the channel 3 and the volume of the second liquid F ₂ either measured externally or also over the part remaining in the channel 3 ermitelt. The evaluation unit 8 calculates the dilution stage or the mixing ratio from the two volumes of the two liquids Fi and F ₂ and brings them into connection with the camera signals. To the third can a

Reference liquid are filled with known dilution stage or mixing ratio in the second chamber 2. Then the evaluation unit 8 compares the

Mix the two liquids Fi and F ₂ with the reference liquid. In addition, the evaluation unit 8, the dilution stages or the

Record mixing ratios, which can then be incorporated into an analysis algorithm of a corresponding assay.

Claims

claims

Method for diluting, mixing and / or aliquoting two liquids (Fi, F ₂ ) using a microfluidic system (S) comprising at least two pumping chambers (1, 2) interconnected by at least one microfluidic channel (3) are, wherein the at least one channel (3) is designed such that at least a portion of the first liquid (Fi) after pumping in the channel (3) remains, characterized by the following steps:

Filling at least one of the pumping chambers (1) with a first liquid (Fi);

Pumping the first liquid (Fi) through the channel (3) leaving a portion of the first liquid (Fi) in the channel (3);

Determining the portion of the first liquid (Fi) remaining in the channel (3);

Rinsing the channel (3) with a second liquid (F ₂ ).

2. The method according to claim 1, characterized in that the part of the first liquid (Fi) remaining in the channel (3) is determined in order to monitor the achievement of a desired mixing ratio and / or a desired dilution stage

3. The method according to claim 1 or 2, characterized in that the part of the first liquid (Fi), which has remained in the channel (3) is determined to the required for the desired dilution, mixing and / or aliquoting volume of the second Determine fluid (F ₂ ).

4. The method according to any one of the preceding claims, characterized

in that the part of the first liquid (Fi) remaining in the channel (3) is determined by the volume of the channel.

5. The method according to any one of claims 1 to 3, characterized in that the part of the first liquid (Fi) remaining in the channel (3), by means of signals from a camera which detects the channel (3) is determined.

6. The method according to any one of the preceding claims, characterized

characterized in that the channel (3) after pumping is completely filled with the first liquid (Fi).

7. The method according to any one of the preceding claims, characterized

characterized in that the chambers (1, 2) are emptied before the channel (3) is flushed with the second liquid (F ₂ ), wherein the first liquid (Fi) is emptied even after the chambers (1, 2) have been emptied Channel (3) remains.

8. Computer program which is set up every step of the

Method according to one of claims 1 to 7 perform.

9. Machine-readable storage medium on which a

Computer program according to claim 8 is stored.

10. Electronic control unit which is set up to

Use of a microfluidic system by means of a method according to one of claims 1 to 7 to dilute, mix and / or aliquot two liquids (Fi, F ₂ ).