DEVICE FOR EXAMINATION OF A BIOLOGICAL SAMPLE

Description

State of the art

[0001] Described here is a device for examining a biological sample, wherein the device is, in particular, a fluidic network for conducting a plurality of parallel examinations of biological samples. The biological sample is, in particular, a sample containing nucleic acid sequences. The examination performed with the device aims, in particular, at identifying a nucleic acid sequence or at determining whether a specific nucleic acid sequence is present in a sample (or not). Such examinations are particularly necessary for decoding genetic codes (DNA sequencing).

[0002] Deciphering the genetic code (DNA sequencing) is a standard procedure in research and medicine.

[0003] A special form of such analyses is so-called next-generation sequencing (NGS). The term "next-generation sequencing" refers to a whole range of different sequencing methods, all of which are essentially characterized by the ability to perform a large number of analyses in a short period of time (especially in parallel). Sequencing-by-synthesis methods are primarily used in "next-generation sequencing" techniques.

[0004] In these methods, the DNA molecules to be sequenced are first amplified (clonally amplified) and bound to a solid phase. Specific nucleic acid sequences are detected using markers (fluorescence-labeled and terminated nucleotides) that attach to the DNA molecules at sites where specific patterns exist. During synthesis of the product strand, the incorporation of individual fluorescently labeled nucleotides into the DNA is measured, which ultimately allows conclusions to be drawn about the sequence. The processes performed in these systems are also known as sequencing-by-synthesis (SBS).

[0005] The sequence reading in SBS is usually done by cyclically performing the following steps: 1) Exposure (= flushing + incubation) of the reaction area with fluorescently labeled and terminated nucleotides. 2) Incorporation of the nucleotides. 3) Washing / rinsing of the reaction area. 4) Optical detection of fluorescence events and identification of where the nucleotides have been incorporated. 5) Exposure (= flushing + incubation) of the reaction area with a solution for removing the terminated nucleotides. 6) Washing / rinsing of the reaction area.

[0006] A challenge for the miniaturization of such a sequencing process is the numerous washing and rinsing steps required to supply the reaction area with the multitude of changing fluids. Commercial sequencers, for example, require up to 100 mL (milliliters) of wash solution per sequencing run.

[0007] US 2007 / 243634 A1 describes a microfluidic device for carrying out a "droplet-based" process, for example for amplifying nucleic acids or for analyzing the sequences of nucleic acids.

[0008] WO 2011 / 002957 A2 describes a microfluidic device for performing a droplet-based method to facilitate such molecular techniques.

[0009] US 2018 / 355350 A1 discloses a method and apparatus for performing sequencing of immobilized nucleic acids in a "droplet format". Disclosure of the invention

[0010] This article describes a device that enables the efficient analysis of biological samples (especially DNA samples) using the sequencing-by-synthesis approach. The described device, in particular, makes it possible to drastically reduce the volumes of individual reagents required for sequencing (reagents containing nucleotides, rinsing solutions, etc.).

[0011] The device described here is a fluidic network for carrying out a large number of tests on biological samples in parallel, comprising a flow array with a large number of reaction spaces, wherein the reaction spaces each have a first channel connection and a second channel connection, wherein the first channel connection is connected to a first supply channel and the second channel connection is connected to a second supply channel, wherein the first supply channel and the second channel connection are connected to one another by a circulation line, wherein at least one component is connected to the circulation line, with which test reagents can be introduced into the reaction spaces of the flow array.

[0012] The core of the described fluidic network is the flow array. The flow array contains the reaction chambers in which the investigations for which the described fluidic network is intended can be carried out. The flow array preferably has a large number of reaction chambers—for example, more than 100 reaction chambers, more than 200 reaction chambers, or even more than 1000 reaction chambers.

[0013] The fluidic network is, in particular, a microfluidic network. The term "microfluidic" here primarily refers to the scale of the microfluidic device. In this context, the microfluidic device is characterized in particular by the fact that the fluidic channels and chambers arranged therein exhibit physical phenomena that are generally associated with microtechnology. These include, for example, capillary effects and effects (especially mechanical effects) related to the surface tension of the fluid. Furthermore, effects such as thermophoresis and electrophoresis are also included. These phenomena are usually dominant in microfluidics over effects such as gravity. The microfluidic device can also be characterized by being at least partially manufactured using a layer-by-layer process, with channels arranged between layers of the layered structure.The term "microfluidic" can also be characterized by the cross-sections within the device used to guide the fluid. Common cross-sections range from 10 µm [micrometers] by 10 µm to 800 µm by 800 µm.

[0014] Preferably, the fluidic network is designed in the manner of a lab-on-chip. In this context, the fluidic network can, for example, be part of a lab-on-chip, for example, arranged in and / or on the chip. Furthermore, the fluidic network can be integrated in and / or on the chip.

[0015] The term "channel connection" refers to connections of the reaction chambers to so-called supply channels, which serve as a type of distributor to distribute fluid from the circulation line to the individual reaction chambers of the flow array. In particular, the first channel connections are connected to a common first supply channel and / or the second channel connections are connected to a common second supply channel.

[0016] The circulation line serves to centrally control the introduction of reagents into the reaction chambers. Liquid plugs (liquid sections separated by a conveying medium, such as oil) in the circulation line can be introduced into the reaction chambers by conveying the liquid through the supply channels and the channel connections.

[0017] The term "component" refers to all components used to introduce reagents into the flow array or to control this introduction, for example conveyors, filters, reservoirs, valves

[0018] It is particularly preferred if the fluidic network is set up to examine a biological DNA sample and to detect nucleic acid sequences in the DNA sample.

[0019] Furthermore, the fluidic network is preferred if at least one conveying device is connected to the circulation line, with which reagents can be conveyed into the reaction spaces via the first supply channel and / or via the second supply channel.

[0020] The conveying device is, for example, a piston or diaphragm pump. Particularly preferably, the conveying device has a specifically reversible conveying direction to enable conveying in both directions in the circulation line and thus to be able to influence whether, and if so, when, and how, liquid plugs containing specific reagents reach the reaction chambers of the flow array.

[0021] The fluidic network is further preferred if at least one reservoir is connected to the circulation line, in which a reagent is provided.

[0022] Particularly preferably, a plurality of such reservoirs are connected to the circulation line. Particularly preferably, reservoirs are provided for reagents that play an active role in the examination process that can be carried out with the described fluidic network (so-called reaction reagents). Particularly preferably, reservoirs are provided for additional fluids that have only a mechanical or fluid-mechanical effect in the operation of the fluidic network (such as, for example, the conveying medium provided between the plugs). These include, for example, fluids that are essentially inert to the reactions carried out during the operation of the described fluidic network. Such fluids serve, in particular, to separate reaction reagents from one another. Such fluids are, in particular, oils.

[0023] The fluidic network is particularly preferred if at least one reservoir is connected to the circulation line, in which a displacement medium is provided.

[0024] A displacement medium can be used to specifically displace liquid. In particular, liquids that interact with other reagents and / or samples during analytical procedures performed with the described device can be displaced. This allows for the separation of reagents from one another and / or of samples and reagents from one another.

[0025] The displacer medium can be a mineral oil, silicone oil, a fluorinated oil or derivatives or mixtures of these oils.

[0026] Particularly preferably, such reservoirs can be connected to the circulation line in such a way that they can be actively switched on or deactivated in a targeted manner, so that fluids from individual reservoirs can specifically enter the circulation line and thus can also be specifically supplied to the reaction spaces in the flow array.

[0027] Furthermore, the fluidic network is preferred if at least one reservoir can be connected to the circulation line with a valve.

[0028] Multiple valves can also be provided to selectively connect reservoirs. For example, valve arrangements can be designed with which the circulation line can be switched either past the respective reservoir or through the respective reservoir in order to supply reagents from the respective reservoir to the circulation line and thus also to the processes within the reaction chambers.

[0029] Furthermore, the fluidic network is preferred if at least one filter is arranged in the circulation line, with which a reagent moving in the circulation line can be filtered (filterable).

[0030] Such a filter can also be optionally activated via valves in the circulation line. It serves to clean the fluids conveyed in the circulation line.

[0031] Furthermore, the fluidic network is advantageous if the reaction spaces in the flow array are arranged in (or to) a two-dimensional matrix. In other words, this means, in particular, that the reaction spaces are arranged relative to each other in such a way that they together form a (two-dimensional) matrix.

[0032] Such an arrangement makes it possible to provide reaction spaces on the flow array in a compact and space-saving manner.

[0033] The fluidic network is further preferred if the reaction spaces in the flow array are separated from each other by separating webs.

[0034] The flow array can particularly preferably be designed as a type of perforated plate, in which the individual holes form the reaction chambers and the material remaining in between forms the separating webs.

[0035] Furthermore, the fluidic network is preferred if retention noses are provided in the reaction spaces, with which particles can be held in the reaction spaces.

[0036] Furthermore, the fluidic network is preferred if an input region for introducing excitation using an excitation unit and a readout region for optically reading the flow array using a detection unit are arranged on a first side of the flow array and a readout region for optically reading the flow array using a detection unit are arranged on a second side of the flow array. In this context, the input region is generally configured for introducing excitation using an excitation unit. In this context, the readout region is generally configured for optically reading the flow array using a detection unit. There are also optical methods in which excitation light and readout of the emitted fluorescence signals occur from the same side. If such methods are used, it is also possible for the input region and the readout region to be formed together on one side (on the first side or the second side of the flow array).

[0037] The first side and the second side (and thus also the coupling region and the readout region) are arranged on (mutually) opposite, flat sides of the flow array and are preferably located on the side of the first supply channel or the second supply channel facing away from the flow array. The excitation unit is preferably configured (e.g., by radiation) to excite optical markers in the reaction spaces of the flow array so that they emit an optical signal. The detection unit (e.g., a camera) is preferably configured to detect such optical signals and thus also enable evaluation.

[0038] Also described here is a fluidic network in which the flow array is designed as a replaceable insert. In this context, the flow array can be formed, for example, in the form of a replaceable module. In particular, the flow array is detachably connectable to the remaining device described (the remaining fluidic network). In this context, it is particularly advantageous if the insert is formed from a material that differs from at least one material of the remaining device.

[0039] The flow array can, in particular, be designed as a cartridge that can be interchangeably inserted into the rest of the described device (the described fluidic network). By inserting the flow array, the reaction chambers of the flow array are connected to the supply channels and thus also to the circulation line.

[0040] The fluidic network is particularly preferred if a diameter of reaction spaces in the flow array is between 1 nm [nanometer] and 500 µm [micrometer], preferably between 1 µm and 50 µm.

[0041] Reaction chambers of this size have proven to be particularly advantageous for the described device (the described fluidic network) and the experiments that can be carried out with it.

[0042] The core of the described device is the flow-through array, which can be imagined as a miniaturized perforated plate. The individual holes in this perforated plate are the reaction chambers in which the individual recognition steps can take place. Preferably, different nucleotides are arranged in each of the reaction chambers, to which the DNA molecules to be sequenced, which can enter the reaction chambers via the supply channels, are immobilized. Furthermore, the DNA sequences to be sequenced can also be produced by a process known in the art called BEAMing. The beads created in this way, on whose surfaces a large number of DNA strands of the same sequence are bound, can be rinsed into the through-hole array in a next step and retained (= fixed) there. By combining a water-insoluble, immiscible phase (e.g.By mixing the aqueous process fluids (e.g., mineral oil) with the aqueous process fluids, advantageous sequencing can be achieved in such a flow-through array according to the following basic principle: In a first step, the through-holes can be loaded / filled with the fluid of the respective step, which is done via the supply channels. In the next step, the top and bottom of the through-hole array can be sealed by layering them with oil, which can also be done via the supply channels.

[0043] In this fluidic state (with the reaction chambers sealed), the respective process steps of "sequencing-by-senthesis" can be performed. Before performing the next process step of "sequencing-by-senthesis," the liquids in the reaction chambers from the previous step can be directly displaced by flushing with oil. Alternatively, or additionally, water-in-oil plugs can be used, allowing a small amount of wash solution (provided and transported as a plug) to be flushed through the vias.

[0044] Also described here is a method for carrying out an analysis of a biological sample comprising the following steps: a) Providing a fluidic network according to one of the preceding claims, b) Providing at least one sample in a flow array of the fluidic network. c) Providing at least two different reagents in the fluidic network, wherein the two different reagents are separated from each other by a displacement medium. d) Applying the at least two different reagents to the sample, wherein direct contact between the reagents is prevented by the displacement medium.

[0045] In step b), the sample can be inserted into the fluidic network, for example, together with the flow array. This is especially true if the sample is designed as a cartridge.

[0046] The separation of different reagents in step c) is preferably carried out by forming plugs of displacement medium in a circulation line of the described device, which plugs separate different reagents from one another.

[0047] The separate exposure of the sample to the various reagents in step d) is preferably carried out by displacing a first reagent preferably completely from the area of ​​the sample or removing it from the sample with the aid of the displacement medium before the sample is exposed to a second reagent.

[0048] The described fluidic network and method, and in particular the combination of a flow array as the sequencing area, the use of water-in-oil mixtures, and the miniaturization of the array, are particularly advantageous. This enables one or more of the following advantages: The described device (the fluidic network described) allows for the reduction of all process fluids in a sequencing-by-synthesis process. This is a major advantage for lab-on-chip sequencing, where only limited quantities of reaction solutions can be stored in advance. Not only are the quantities of required wash reagents reduced, but also the quantities of reaction solutions containing expensive enzymes. This enables a significant cost reduction. The flow array allows the excitation and detection units required for the optical readout of a sequencing reaction to be placed on two different sides of the through-hole array, resulting in improved optical efficiency and more configuration options. The flow array can be designed as an insert (like a DNA microarray), which provides freedom in the choice of materials and advantages in the assembly process of the flow array.The described fluidic network enables a sample-to-sequence process. This has the enormous potential to detect DNA signatures or even SNPs that cannot be detected by an on-chip probe. Due to the constant occurrence of mutations in the target genome, a sequencing workflow is key to the future viability of a lab-on-chip system. Using the described fluidic network, it is possible to run the sequencing reaction until gene signatures are unambiguously determined. For example, it is also possible to incorporate only a single nucleotide if the sole purpose is to detect SNPs.

[0049] The described device is explained in more detail below with reference to the figures. The figures show only a preferred embodiment, to which the disclosure of the described device is not limited. They show: Fig. 1: a described fluidic network Fig. 2: a section of the fluidic network according to Fig. 1 , Fig. 3: a first embodiment of a flow array, Fig. 4: a second embodiment of a flow array, Fig. 5: a third embodiment of a flow array, Fig. 6: a fourth embodiment of a flow array, and Fig. 7: an illustration of operations of a method that can be carried out by means of the described device.

[0050] In Fig. 1 An exemplary described fluidic network 1 for sequencing is shown. The microfluidic network 1 preferably comprises a circulation line 6 and a flow array 2 with reaction chambers 14. The reaction chambers 14 form flow cells through which a fluid circulating in the circulation line 6 flows in parallel. Colonies of immobilized DNA molecules are preferably located in the reaction chambers. A sequencing reaction (=decoding of the base sequence) can take place in each individual reaction chamber 14. The reagents provided for this purpose flow, for example, from a first side 22 through a first supply channel 16 into first channel connections 20 of the reaction chambers 14. The first side 22 is preferably an underside of the flow array 2. This means that the flow array 2 is preferably (geodetically) aligned so that it is flowed through from bottom to top.The reagents exit the reaction chamber 14 at second channel connections 21 on a second side 24 of the flow array 2 and then enter a second supply channel 19. The first supply channel 16 preferably forms an inflow channel into the reaction chambers 14. The second supply channel 19 preferably forms an outflow channel out of the reaction chambers 14. The first supply channel 16 and the second supply channel 19 are connected to each other via the circulation line 6.

[0051] The flow array 2 provides a plurality of reaction chambers 14 arranged parallel to one another. Various reservoirs 5 are connected to the microfluidic network 1, separated by valves 3. These reservoirs 5 hold the various reagents intended for a sequencing reaction. For a sequencing-by-synthesis analysis, for example, labeled nucleotides (e.g., ddNTPs; A = adenine, G = guanine, T = thymine, C = cytosine) are used, which are incorporated into the nucleic acid sequence to be read by a polymerase (e.g., "Enzyme 1"). A terminator is attached to the incorporated nucleotides, preventing the incorporation of further nucleotides. In a sequencing reaction, this terminator is removed before the addition of another nucleotide, for example, by an "Enzyme 2." Further reagents include the sequencing primer, which defines the starting point of the sequencing.In further reservoir(s) there are wash buffers by means of which the reaction solutions in the flow array 2 can be washed away before the next (reaction) step.

[0052] Optionally, the network contains a filter 7. Filter 7 can be used to remove components absorbed by the wash buffer. Filter 7 can comprise a dielectrophoretic unit, which achieves the filtering effect and can be used to remove nucleotides, for example, from a solution. This enables "wash buffer recovery" for the advantageous reduction of the intended wash buffer. At least one conveying device 4, which can be a membrane pump or a peristaltic pump, is located in the network. The fluidic network 1 also has a waste reservoir 11 for collecting reagents that are no longer used. A displacement medium is stored in a reservoir (not shown), which can be used for the physical separation of the reagents or for the direct displacement of reagents located in the flow array 2 (i.e., a type of wash support).The displacer medium can be a mineral oil, silicone oil, a fluorinated oil or derivatives or mixtures of these oils.

[0053] In Fig. 2 is an exemplary fluidic section of a sequencing in a described fluidic network 1. The focus is on the Fig. 2 the described flow array 2 of the fluidic network 1. The flow array includes the previously described reaction chambers 14 with the first channel connections 20 and the second channel connections 21, as well as the first supply channel 16 on the first side 22 and the second supply channel 19 on the second side 24 of the flow array. A coupling region 25 is arranged on the first side 22, at which an excitation unit 23 can transmit excitation to the reaction chambers 14. Thus, molecules in the reaction chambers 14 can be excited so that they emit optical signals. Such optical signals can be detected in a readout region 26 on the second side 24 with a detection unit 27.

[0054] In a Fig. 2 In the section of the circulation line 6 shown, several phases of reagents can be seen, which are designated by letters. Here, for example, aqueous phases (A, D, E, F) are separated from one another by at least one oil phase C (a displacement medium). Individual phases (A, D, E, F) form liquid plugs 12 in the circulation line 6, which are each separated from one another by phase boundaries 13 and which are fed to the flow array 2 or the reaction spaces 14 contained in the flow array by means of a conveying device in the circulation line 6 (see Fig. 1 ) can be supplied in a targeted manner. This is achieved by the conveying device conveying until the respective liquid plugs 12 are in the reaction chambers 14. To support the use of the conveying device for the precise conveying of the liquid plugs 12 into the reaction chambers 14, the excitation unit 23 and the detection unit 27 described above can also be used.

[0055] A wash buffer (generally an aqueous phase) can also be present before or after the oil phase (or two different phases connected in sequence), or in the middle of two oil phases. DNA colonies B are immobilized on the walls of the cells of flow array 2 (how and where they come from will be explained later). In the figure, the cells (and the surrounding space) are filled with solution A. In this example, this is the binding of a sequencing primer. Plug C, which is in contact with B, is a combination of wash buffer and displacement medium. This wash step removes the reagents from B from the cells. The multiphase system is now transported through the conveyor unit until plug D completely fills the cells of the array. In this related example, plug D is a mixture of enzyme 1 and ddNTP "A."If the array is loaded with plug D, the enzyme (a polymerase) incorporates the nucleotide at a "T" present in the strand to be read (due to the base pairing A-T). In the next step, the reaction solution D is washed away using the wash buffer C following D, and the fluorophores present on the incorporated nucleotides are optically detected. This is preferably done using the described excitation unit 23 and the described detection unit 27. Next, the fluorophores are optically detected using the method shown in . Fig. 2 A conveyor unit (not shown) transports the next fluid packet, Plug E, into the cells. Plug E is, for example, Enzyme 2, which removes the nucleotide terminators. The wash plug C following E is again the combination of wash buffer and displacement medium. Plug F is now transported into the cells using the pump unit. F is a mixture of Enzyme 1 and, for example, ddNTP "C." If Plug F is applied to the array, the enzyme incorporates the nucleotide at a "G" present in the strand to be read (due to the G-C base pairing). This cyclic process is continued until the desired read length is reached. The exact positions of the phase boundaries (or in other words, the positions of the various fluid plugs) can be detected by optical control.

[0056] The detection performed with the detection unit is preferably an optical check. For example, the detection unit is a camera with which the flow array 2 and / or the circulation line 6 can be monitored and with which the phase boundaries between the liquid plugs can be detected. The aqueous phases and / or the oil phases can be colored with various dyes or fluorophores (e.g., HEX, FAM dyes; soot particles, food colorings, etc.). This positioning can be used to control which solutions are reused, which are fed to a waste container on the circulation line 6 or a filter from the circulation line 6. An example of liquid reuse is the enzyme mixture Enzyme1 + ddNTP "A", "G", "T", "C". These reagents can be returned to the respective reservoirs to be removed for a new installation cycle.In the same way, the inert oil plugs can be returned to the respective reservoir.

[0057] Thus, with the described fluidic network, three approaches to saving buffer volumes are possible: 1) Reuse of volumes by returning them to their reservoirs; 2) Use of two-phase mixtures for the reduction of dead volumes and the precise pumping of defined volumes; 3) Filtration options for wash solutions for reuse of the wash solution.

[0058] Embodiments are described below to sequence the DNA colonies ( Abbildung 2 , B) to provide / immobilize in the colonies.

[0059] Fig. 3 shows a cross-section of the flow array 2. The individual reaction chambers 14 can be seen, which are separated from one another by dividers 15 and into which the respective reaction liquids can be introduced via the supply lines 16. The reaction chambers 14 form flow cells of the flow array. The diameter of the reaction chambers 14 or the flow cells is between 1 and 500 µm, preferably between 1 µm and 50 µm. DNA primers can be pre-positioned in the reaction chambers 14 or in the flow cells ("targeted sequencing") in order to generate amplification products in the cells, which are immobilized on the walls of the respective reaction chambers 14 / flow cells. Advantageously, a different primer pair is pre-positioned in each of the reaction chambers 14 / flow cells in order to be able to read different DNA molecules in the different cells.A solution containing at least the DNA molecules to be sequenced and a polymerase is introduced into such a flow array 2. This solution is then introduced into the flow cells / reaction chambers 14 of the flow array 2. For the subsequent reaction, the flow array is sealed with oil "H" such that the first channel connections 20 and the second channel connections 21 (top and bottom) of the reaction chambers 14 are sealed with oil. This condition is also shown in . Fig. 3 After performing an amplification reaction (PCR, LAMP, RPA, SDA, ...), the resulting DNA colonies "G" are immobilized on the walls of the respective reaction chambers 14. This state is also shown in Fig. 3 The sequential filling and exchange of solutions in the reaction chambers 14 is carried out as previously described, namely by precisely conveying the fluids in the circulation line.

[0060] In Fig. 4 Another variant is shown of how the DNA colonies to be sequenced can be present in the cells. Here, a new form of a flow array 2 with reaction chambers 14 is shown, where Fig. 4 shows only a section of the flow array 2. In particular, the first supply channel 16 and the second supply channel 19 are not shown here. The focus of the Fig. 4 lies on the representation of the separating dividing webs 15, which separate the individual reaction chambers 14 of the flow array 2 from each other. The reaction chambers 14 are equipped with retention lugs 17, with which particles 18 can be retained. The DNA colonies in the reaction chambers 14 are provided here on the particles 18. In the context of a BEAMing process, microparticles are created, on whose surface the DNA colonies to be sequenced are immobilized. If a solution containing these particles 18 is passed through a Fig. 4 If the particles 18 are flushed through the flow array 2 shown, they are fixed / positioned by the retention tabs 17 present in the flow array 2. This creates, for example, a sequenceable flow array 2. The diameter of the openings defined by the retention tabs 17 is slightly smaller than that of the particles. The diameters of the reaction spaces 14 here are between 1 nm and 100 µm. Such a flow array containing particles 17 can be sequenced using a microfluidic multiphase approach - as described above.

[0061] Fig. 5 shows another possibility to generate DNA colonies to be sequenced in the reaction chambers 14 of a flow array 2. Also in Fig. 5 The flow array 2 is shown only schematically. Here, at least the inner walls of the cells and the edge areas on the top and / or bottom are coated with a hydrophilic coating 30. The hydrophilic coating 30 on the top and bottom are shown in Fig. 5 shown above as black dots. The rest of the array is preferentially hydrophobic.

[0062] The flow array 2 has (as already described) reaction spaces 14 with a cell diameter of 1 nm to 100 µm. If such an array is exposed to an aqueous phase, liquid droplets remain in the hydrophilic areas, as in Fig. 5 This variant further saves reaction solution and further increases the cell density. A further advantage is that DNA colonies can be generated using digital PCR. Here, the number of DNA molecules to be sequenced is adjusted so that it is relatively small. If a solution containing at least the DNA molecules and a polymerase is poured into the cells of the array, the molecules are distributed among the cells according to the Poisson distribution (followed by another amplification reaction, during which the amplification products are immobilized on the cell walls).

[0063] Fig. 6 shows yet another embodiment of a flow-through array. Here, the cells / reaction chambers 14 of the flow-through array can be formed with a fabric-like material 18 or a porous material. This has the advantage that the filling of the cells / reaction chambers 14 is assisted by capillary forces, the intended reaction volumes are further reduced, and diffusive washing is enabled.

[0064] Fig. 7 clarifies the processes of the described procedure. In Fig. 7 It is shown that one side of the flow array can be sealed with an oil phase 28 during the entire sequencing process (or only during specific steps). This allows individual aqueous phases 29 of reagents used for a reaction to be flushed over the array on the other side. The washing action here occurs almost exclusively by diffusion. This fluidic principle ("semi-sealed array") can also be applied to a flow array, as in Fig. 4 shown. This further reduces the required amount of washing solution.

[0065] The process can be verified by optical inspection of a reaction carrier, especially the sequencing area, and analysis of the process fluids used.

Claims

1. Fluidic network (1) for parallel performance of a multiplicity of analyses of biological samples, comprising a flow array (2) having a multiplicity of reaction spaces (14), wherein the reaction spaces (14) each have a first channel connection (20) and a second channel connection (21), wherein the first channel connections (20) are connected to a first supply channel (16) and the second channel connections (21) are connected to a second supply channel (19), wherein the first supply channel (16) and the second supply channel (19) are connected to one another by means of a circulation line (6), wherein the circulation line has connected thereto at least one component (3, 4, 5, 7) by means of which test reagents are introducible into the reaction spaces (14) of the flow array (2).

2. Fluidic network (1) according to Claim 1, wherein the fluidic network (1) is configured for analysing a biological DNA sample and for identifying nucleic acid sequences in the DNA sample.

3. Fluidic network (1) according to Claim 2, wherein the circulation line (6) has connected thereto at least one conveyor (4) by means of which reagents are conveyable into the reaction spaces (14) via the first supply channel (16) and / or via the second supply channel (19).

4. Fluidic network (1) according to any of the preceding claims, wherein the circulation line (6) has connected thereto at least one reservoir (5) in which a reagent is provided.

5. Fluidic network (1) according to any of the preceding claims, wherein the circulation line (6) has connected thereto at least one reservoir (5) in which a displacement medium is provided.

6. Fluidic network (1) according to Claim 4, wherein at least one reservoir (5) is connectable to the circulation line (6) by means of a valve (3).

7. Fluidic network (1) according to any of the preceding claims, wherein the circulation line (6) has arranged therein at least one filter (7) by means of which a reagent moved in the circulation line (6) is filterable.

8. Fluidic network (1) according to any of the preceding claims, wherein the reaction spaces (14) in the flow array (2) are arranged in a two-dimensional matrix.

9. Fluidic network (1) according to any of the preceding claims, wherein the reaction spaces (14) in the flow array (2) are separated from one another by means of partition webs (15).

10. Fluidic network (1) according to any of the preceding claims, wherein the reaction spaces (14) have provided therein retention projections (17) by means of which particles can be held in the reaction spaces.

11. Fluidic network (1) according to any of the preceding claims, wherein a first side (22) of the flow array (2) has arranged thereon a coupling-in zone (25) for introduction of an excitation by means of an excitation unit (23) and a second side (24) of the flow array (2) has arranged thereon a reading zone (26) for optical reading of the flow array (2) by means of a detection unit (27).

12. Fluidic network (1) according to any of the preceding claims, wherein the flow array (2) is realized as an exchangeable insert component.

13. Fluidic network (1) according to any of the preceding claims, wherein a diameter of reaction spaces (14) in the flow array (2) is between 1 nm [nanometer] and 100 µm [micrometer].

14. Method for performing an analysis of a biological sample, comprising the following steps: a) Providing a fluidic network (1) according to any of the preceding claims. b) Providing at least one sample in a flow array (2) of the fluidic network. c) Providing at least two different reagents in the fluidic network (1), wherein the two different reagents are separated from one another by a displacement medium. d) Exposing the sample to the at least two different reagents, wherein direct contact between the reagents is prevented by the displacement medium.