EP2621633A1 - Microfluidic chip comprising several cylinder-piston arrangements - Google Patents

Abstract

The invention relates to a microfluidic arrangement comprising a substrate (10, 10, 50) in which a mircofluidic structure comprising several adjacent channels (12, 12') and at least one common supply line (14), into which the adjacent channels (12, 12') merge, is formed. Each of the adjacent channels (12, 12') form the cylinder of a cylinder-piston arrangement for receiving an associated piston (22). The invention also relates to a method for producing said type of microfluidic-arrangement.

Description

 Microfluidic chip with multiple cylinder-piston arrangements

description

The invention relates to a microfluidic device with a substrate, in particular in the form of one or more microfluidic chips, also referred to as Lap-on-a-chip system, in which a microfluidic structure for performing chemical, biological, biochemical and / or medical Analysis and / or detection method (short: tests), such as immunoassays, DNA assays or the like is formed. In such a microfluidic arrangement, a sample to be examined is distributed via a central feed line to a plurality of separate reaction chambers or detection regions in which, for example, different reaction components for the sample to be analyzed are immobilized or otherwise introduced or introduced. The invention further relates to a method for producing a corresponding microfluidic device.

Microfluidics is characterized by a controlled movement of smallest sample volumes in the micro or nanoliter range. An exact control of reactions in microchannels or microchambers within the microfluidic chips is thereby possible. The microfluidic control is therefore a great challenge in particular because, due to the very small dimensions of the channels and chambers, surface effects play a very dominant role, which complicates reproducible processes within the microfluidic arrangement. This problem is particularly in the active filling of several similar channels or chambers to bear when created for a larger number of samples the same experimental conditions, ie in particular the multiple channels are all to be filled with the same sample volumes. In addition, similar to the high-throughput screening, the filling of the multiple channels should be synchronized in order to synchronize tests without loss of time. to run chronically in all channels. So far, no actuators in the field of microfluidic arrangements are known, which meet the above-described requirements.

Accordingly, it is an object of the present invention to provide a microfluidic device capable of filling a plurality of adjacent channels synchronously and with high volumetric accuracy for the purpose of sample analysis. The object of the invention is also to provide a method for producing such a microfluidic device.

The invention is achieved by a microfluidic device having the features of patent claim 1 and by a method according to patent claim 13.

The microfluidic device according to the invention comprises a substrate in which a microfluidic structure is formed having a plurality of adjacent channels and at least one common feed line into which the adjacent channels open, each of the adjacent channels receiving the cylinder of a cylinder-piston arrangement an associated piston forms.

The principle for active filling of the adjacent channels or reaction channels is similar to that of a multipipette, as known for example from US Pat. No. 3,855,868, this principle being applied according to the invention in the field of microfluidics, in particular lap-on-a-chip systems. This is in contrast to the known multipipettes special because the cylinder is formed as an integral part of the substrate of the microfluidic device, so for example, the one or more chips. Such a substrate is known to have a flat, planar shape, similar to the format of a check card, with flat top and bottom sides and a plurality, typically four, narrow end faces along the edge. The channels typically extend as grooves on the top and / or bottom or as holes in the plane, wherein the grooves are closed by a cover in the form of a film from the environment. Further, filling or communicating holes communicating with the channels may be provided perpendicular to the plane in the substrate.

Each of the adjacent channels is assigned a piston. For example, the pistons may be in the form of wires which are preferably inserted laterally through openings in one or more of the end faces of the substrate into the cylinders and are moveable back and forth along the longitudinal axis in the cylinders.

The invention is advantageously further developed in that a sealing arrangement which is stationary relative to the microfluidic structure is provided for sealing the piston in the cylinder.

Unlike cylinder-piston assemblies in which a sealing element is usually provided at the front end of the piston, the seal assembly according to the invention is not moved with the piston, but the piston moves relative to the seal assembly. This has the advantage, in the case of an ideal design, that no contact takes place between the piston and the cylinder wall. Any functionalization of the channel surface in the cylinder region, for example by immobilization of a reaction component, is thereby not impaired when the piston is moved back and forth.

The sealing arrangement preferably has a contiguous sealing element which spans the piston side over several adjacent channels.

Such a central sealing element for sealing all adjacent cylinder-piston assemblies is only made possible by the fact that the seal assembly is arranged stationary to the microfluidic structure and not to the piston. The cohesive, central sealing element is above all manufacturing technology easier to implement than individual sealing elements for each of the adjacent cylinder-piston assemblies.

Advantageously, the sealing arrangement has a sealing channel, which crosses the several adjacent channels, for receiving the continuous sealing element.

In this channel, the sealing element can be introduced, for example, in the form of a high-viscosity fluid (eg, fat) or in the form of an elastomer (rubber, silicone) or generally as a polymeric plastic.

As an alternative embodiment of the invention, the sealing element is attached to the end face of the substrate of the microfluidic device.

Particularly preferably, the sealing element is connected by injection molding with the substrate of the microfluidic device. This applies both to the design with a sealing channel in the sealing channel and with a sealing element attached to the end face.

The substrate of the microfluidic device itself is also preferably produced by injection molding. In this case, the sealing element is particularly preferably inserted or attached in a two-component injection molding process.

The advantage lies in a cost-effective production and a high manufacturing accuracy inherent in the manufacturing process.

Particularly preferably, the method for producing a microfluidic arrangement of the type described above provides that the microfluidic device is produced by injection molding, wherein the piston in a Inserted injection mold and molded with at least one plastic.

If the microfluidic arrangement is produced as such by injection molding, then preferably all the microfluidic structures on the substrate are already part of the injection-molded part, so that mechanical post-processing can largely be dispensed with. The pistons are inserted into the mold either after spraying the substrate or with the finished substrate and then overmoulded with the polymer / elastomer of the sealing element.

Or they are first inserted into the mold and then encapsulated first with the substrate plastic of the microfluidic device and then with the polymer / elastomer of the sealing element. Decisive in each case is the choice of material to achieve the desired seal and sufficient mobility of the piston.

Preferably, the plurality of pistons associated with the adjacent channels are coupled together by a common actuator.

By such a common actuator all pistons can be moved synchronously by a common drive or manually. This drive principle is known from the application of the multipipette.

The common supply line preferably has a sufficient volume in the flow direction in front of the orifices of all adjacent channels, which ensures that all adjacent channels can be filled simultaneously and uniformly. The common supply line is preferably formed by a transversely to the adjacent channels extending channel with two accesses, of which at least one is particularly preferably closed gas-tight.

Other objects, features and advantages of the invention will be explained in more detail by means of embodiments with the aid of the drawings. Show it:

Figure 1 is a plan view of a first embodiment of the microfluidic device;

Figure 2 is a sectional side view of the first embodiment of

 Microfluidic arrangement according to Figure 1;

Figure 3 is a sectional side view of a second embodiment of the microfluidic device according to the invention;

FIG. 4 shows an enlarged perspective view in partial section of the microfluidic arrangement according to the invention;

FIG. 5 is a perspective view of a third embodiment of the microfluidic device with detection module; and

FIG. 6 is a plan view of a fourth embodiment of the microfluidic device distributed over four microfluidic chips.

FIGS. 1 and 2 schematically show a first embodiment of the microfluidic device according to the invention. The microfluidic device is located on a single microfluidic chip. This has a substrate 10, in which a plurality of adjacent channels 12 and a common feed line 14, in which the adjacent channels 12 open, are formed. The plurality of adjacent channels 12 are incorporated in the form of parallel grooves and the common feed line 14 in the form of a wider groove extending perpendicular to the mouth-side end of the parallel channels 12 on an upper side of the substrate 10. The top of the substrate is closed with a cover 16 to the environment, so that from the grooves circumferentially closed channels are formed on all sides.

The parallel channels 12 have a flat portion 18, which is ready for the reaction or detection of the fluid to be tested, hereinafter referred to as function section. The flat functional section 18 is adjoined by an abruptly recessed section 20, which forms the cylinder of a cylinder-piston arrangement, hereinafter called the cylinder section. In each of the cylinders thus formed, an associated piston 22 is received. The piston 22 displaces a defined volume within the cylinder portion 20 and can be moved back and forth in the cylinder portion 20 parallel to its longitudinal axis, which ideally coincides with the longitudinal axis of the channel 12, thereby increasing or decreasing the displaced volume.

In the substrate 10, a plurality of adjacent channels 12 on the piston side, ie on the opposite side of the feed line 14, transverse sealing channel 24 is formed from the top into the substrate 1 0. As a crossing in the context of this document, such an arrangement is referred to, in which, as shown in Figure 1, the channels 12, respectively, the cylinder sections 20, and the sealing channel 24 does not intersect directly but extend transversely to each other at a distance. The sealing channel 24 receives over the width of all parallel channels 12 away continuously contiguous sealing element 26. The pistons 22 are inserted through frontal openings 27 in the cylindrical portions 20 of the parallel channels 12. So that the channels 12 are not connected via these openings 27 to the outside world, the sealing element at this point - or another, as shown in Figure 3 - but in any case arranged on the piston side. The sealing element also has passage openings for the pistons, but is elastically in contact therewith, preferably under radial pressure. The sealing element therefore preferably consists of an elastomer and is particularly preferably connected to the substrate 10 by injection molding.

The plurality of pistons 22 associated with the adjacent channels 12 are guided in the openings 27 through the substrate 10 and the sealing element 26 parallel to the cylinder sections 20. The pistons 22 are coupled together at their projecting from the substrate 10 ends 28 by a common actuator 30 in such a way that they can be pulled out of the associated cylinders only synchronously and in parallel or inserted into this. In this way, it is ensured that - assuming identical profiles of the pistons - the change of the displaced volume within the cylinder sections 20 in all adjacent channels 12 is the same, so that an equal underpressure or overpressure forms in the channels 12 simultaneously. This ensures that the fluid to be examined uniformly flows from the common supply line 14 into the functional sections 18 of the parallel channels 12 or vice versa and finally in all parallel channels 12 the same volume of fluid is moved. This makes the filling of the plurality of adjacent channels 12 and thus the test in the microfluidic device despite the surface effects mentioned above very reliable, since the pressure change takes place synchronously in all channels and is the same size, but the channels 12 only communicate with each other via the feed line 14 and piston (or suction when sucking) are separated on the side.

Although preferred for parallel tests under the same conditions, it is not relevant to the invention that the adjacent channels 12 or the associated channels Neten piston 22, as shown in Figure 1 and Figure 2, have identical dimensions. In principle, it is also conceivable that in selected channels with the same piston stroke larger or smaller volumes of fluid are moved, for example, by changing the piston cross section accordingly. This may be desired, for example, if different detection reactions with markers of different sensitivity are carried out simultaneously with a device of the type according to the invention, so that different amounts of fluid are required.

The adjacent channels are, as shown in Figure 1, preferably arranged substantially parallel, so that the joint operation of the piston can be done in a simple manner, with high precision and little effort. In practice, a non-parallel arrangement of the channels would not be excluded. However, this requires, for example, flexible pistons or a flexible common actuator, which could affect the sealing and / or the precision of the volume change and therefore is not preferable without special reason.

The illustrated in Figure 3 embodiment of the microfluidic device according to the invention differs from that of Figure 2 by adjacent channels 12 ', which are formed in its cylinder portion 20' in the form of a bore and in by means of a transverse bore 34 perpendicular to the plane of the substrate 10 'continue into the otherwise same functional portions 18, which then open in the manner shown in Figure 1 in the common supply line 14.

The pistons 22 almost completely fill the space of the cylindrical cylinder sections 20 ', which are small compared to the example of FIG. 2, so that when the pistons 22 are pulled out there is a greater relative change in the volume of the channels 12'. The consequence is that a larger pressure change or, in the case of When the piston 22 is withdrawn, the actuation speed thereof causes a rapid pressure drop to act on the fluid present in the common supply line, which consequently is sucked into the functional channel 18 more rapidly.

A further difference is that the embodiment according to FIG. 3 has a contiguous sealing element 26 'which spans the piston side over several adjacent channels 12' and which is mounted on the front side of the substrate 10 '. Also, this sealing element is preferably made of an elastomer, which is connected by injection molding with the end face 32 of the substrate 10 '.

FIG. 4 shows an enlarged perspective detail of an embodiment of the microfluidic arrangement according to the invention similar to that according to FIGS. 1 and 2. From Figure 4 it can be seen that the piston 22 has a significantly smaller cross-section than the associated cylinder portion 20 and therefore a displacement of the piston results in a lower relative volume and thus pressure change than in the example of Figure 3. This teaches that appropriate design measures at a certain speed of the piston feed the desired pressure change can be adjusted.

Furthermore, it can be seen in FIG. 4 that the piston has a cylindrical geometry. Preferably, the piston 22 is formed of a straight piece of wire. It should be noted at this point that the structures shown here have dimensions in the millimeter range or in the submillimeter range. Therefore, the cylindrical geometry of wire-shaped pistons represents the simplest embodiment of pistons to be realized.

It can also be seen in the illustration of FIG. 4 that the cylinder section 20 not only has a larger cross section than the piston but also a has another cross-sectional shape, namely a rectangular. In this sense, when the term cylinder is used in the present specification, the function of the corresponding channel or channel section is meant as part of a cylinder-piston arrangement and not a channel / channel section with a strict cylinder geometry, ie a round base.

Finally, FIG. 4 clearly shows that the piston 22 does not touch the wall of the cylinder section 20 because of its smaller cross section, which remains essentially the same over its entire length, so that a mechanical effect on a reactive substance applied, for example, to the inner surface of the cylinder wall 20 is avoided becomes. This, of course, requires sufficient processing precision in terms of parallelism of cylinder section and piston or piston guide.

The embodiment of the microfluidic device according to the invention according to Figure 5 differs from those described above, in particular by its more complex shape. Similar to the examples described above, the arrangement is formed on a chip providing the substrate 50. In the substrate, however, two blocks 52, 54 each having 32 parallel, adjacent channels are formed in this embodiment, each of which form the cylinder of a cylinder-piston assembly and each associated with a piston. All sixty-four pistons of both blocks are coupled together by a common actuator 56 such that they can only be withdrawn from their cylinders together and in parallel.

The common supply line 58 comprises in this embodiment two accesses, namely an inlet 60 and a drain 62. In the flow direction behind the inlet 60 is a reservoir 64 for receiving a larger amount of the fluid to be tested, which is sufficient to the functional sections to fill all 64 parallel channels. In the flow direction behind the reservoir 64, the adjacent channels open in sequence into the feed line 58. The feed line 58 has at this point a sufficiently large cross-sectional area in order to be able to fill all parallel channels simultaneously and uniformly when pulling out the pistons at the required speed.

The filling takes place as follows: The fluid is first introduced into the common supply line 58 while the reservoir 64 is filled. If this is done, an access of the supply line, here the drainage 62 closed gas-tight. Subsequently, the pistons are pulled out by means of the common actuating element, for example using a linear drive from the cylinder portions of the parallel channels, whereby in all hitherto filled with air or gas channels, a negative pressure. Due to the negative pressure, the fluid flows from the common supply line and in particular from the reservoir 64 in the parallel channels until a pressure equalization has taken place. This is achieved with suitable dimensioning of the pistons, the functional sections of the parallel channels and the piston stroke when the functional sections are filled as far as desired. After filling the parallel channels of the closed drain 62 of the common feed line 58 is opened again and the remaining fluid withdrawn by applying a pressure difference between inlet and outlet from the common supply line and the reservoir 64 thus between the individual now in the parallel channels pending liquid plugs no liquid bridge exists. In this way, cross-contamination between the individual liquid plugs in the adjacent channels is prevented. The emptying of the parallel channels can take place in the reverse direction by returning the pistons into the cylinder sections, whereby an overpressure is formed, which shifts the fluid sample into the common supply line. This is preferably done with a closed access to give the fluid a desired transport direction. In the right half of FIG. 5, an electronic detection unit 70 is shown by way of example, to which two foil electrodes 74 are connected as part of an electrochemical sensor system via two plug connections 72, for example.

FIG. 6 shows a further exemplary embodiment of the microfluidic arrangement according to the invention, which, similar to the arrangement from FIG. 5, has two blocks of parallel, adjacent channels and associated pistons. A key difference of this arrangement is that it extends over a total of four microfluidic chips providing a common substrate. By way of example, the two chips 80, 82 shown below each have a block with the cylinder-piston arrangements and the two upper chips 84, 86 each have a portion of the common supply line 88, in which only in the chip 86, a reservoir 90 is integrated for the fluid sample. Such a microfluidic arrangement requires additional connection channels 92 (not shown in detail) for connecting the cylindrical portions 94 of the parallel channels on the chips 80 and 82 to the respective associated functional portions 96 of the parallel channels on the chips 84 and 86. Also needed a connection channel (not shown) for bridging the common lead 88 from the chip 84 to the chip 86.

LIST OF REFERENCE NUMBERS

10, 10 'substrate

 12, 12 'parallel, adjacent channels

 14 common supply line

 16 cover, foil

 18 reaction / detection or general functional section

20, 20 'cylinder section

 2 pistons

 4 sealing channel

 26, 26 'sealing element

 8 outboard piston end 0 common actuator

 2 front side of the substrate 0 substrate

 2, 54 blocks of adjacent, parallel channels

 6 common actuator

 8 common supply line 0 access, inlet

 2 access, expiry

 4 Reservoir 0 electronic module

 2 plug connection

4 electrode 80, 82 microfluidic chip

84, 86 microfluidic chip

88 common supply line

90 reservoir

 92 connection channels

 94 cylinder section

 96 reaction / detection or general functional section

Claims

claims 1 . Microfluidic arrangement with a substrate (10, 1 0 ', 50), in which a  microfluidic structure is formed, which has a plurality of adjacent channels (12, 12 ') and at least one common feed line (14) into which the adjacent channels (12, 12') open, wherein each of the adjacent channels (12, 12 ') Cylinder of a cylinder-piston assembly for receiving an associated piston (22) forms. 2. Microfluidic device according to claim 1, each with one of each of the adjacent channels (12, 12 ') associated piston (22),  characterized du rch a relative to the microfluidic structure stationary seal assembly for sealing the piston (22) in the cylinder. 3. microfluidic device according to claim 2,  characterized in that the sealing arrangement comprises one of the several adjacent channels (12, 12 ') on the piston side spanning, contiguous sealing element (26, 26'). 4. microfluidic device according to claim 3,  characterized in that the sealing arrangement has a sealing channel (24) crossing the several adjacent channels (12, 12 ') for receiving the continuous sealing element (26, 26'). 5. microfluidic device according to claim 3,  characterized in that the sealing element (26, 26 ') is attached to the end face of the substrate of the microfluidic device. 6. microfluidic device according to claim 4 or 5, characterized in that the sealing element (26, 26 ') consists of a polymer. 7. microfluidic device according to claim 6,  characterized in that the sealing element (26, 26 ') is connected by injection molding with the substrate of the microfluidic device. 8. Microfluidic device according to one of the preceding claims,  characterized in that the plurality of adjacent channels (12, 12 ') associated piston (22) by a common actuating element (30, 56) are coupled together. 9. Microfluidic device according to one of the preceding claims,  characterized in that the pistons (22) are inserted through frontal openings in the substrate of the microfluidic device. 10. Microfluidic device according to one of the preceding claims, characterized in that the common feed line (58, 88) in front of the mouths of all adjacent channels (12, 12 ^! ) Has a sufficient volume, which ensures that all adjacent channels (12, 12 ') are filled simultaneously and uniformly. 1 1. Microfluidic device according to one of the preceding claims,  characterized in that the common feed line (58, 88) is formed by a transversely to the adjacent channels (12, 12 ') extending channel with two accesses (60, 62). 12. Microfluidic device according to claim 1 1, characterized in that at least one of the accesses (60, 62) is closed gas-tight. 1 3. A method for producing a microfluidic device according to one of claims 2 to 12,  characterized in that the microfluidic device is produced by injection molding, wherein the pistons (22) are inserted into an injection mold and encapsulated with at least one plastic. 14. The method according to claim 13,  characterized in that the pistons (22) are inserted after the injection of the substrate or with the finished substrate in the injection mold and then encapsulated with the polymer or elastomer of the sealing element.