阅读说明：本技术 提高微流体泵或阀的定量精度的方法以及用于实施所述方法的焊接装置和张紧装置 (Method for increasing the dosing accuracy of a microfluidic pump or valve, and welding device and tensioning device for carrying out said method ) 是由 尼克拉斯·弗里希 亚历山大·克雷默斯 卡尔海因茨·希尔登布兰德 克里斯托夫·皮特里 于 2019-11-29 设计创作，主要内容包括：本发明涉及一种基于柔性覆盖薄膜/隔膜和阀槽提高微流体泵和阀的定量精度的方法,其中借助激光束对所述隔膜的朝向所述阀槽的表面进行加热。(The invention relates to a method for increasing the dosing accuracy of microfluidic pumps and valves on the basis of a flexible cover film/diaphragm and a valve housing, wherein the surface of the diaphragm facing the valve housing is heated by means of a laser beam.)

1. A method for improving the dosing accuracy of a microfluidic pump 1, 2, 3 or valve having a flexible membrane (4) and a valve body (8) comprising at least one valve groove (5, 6, 7), wherein the flexible membrane (4) is fixed to the valve body (8) so as to cover the valve groove (5, 6, 7), characterized in that a surface (9) of the membrane (4) facing the valve groove (5, 6, 7) is heated by means of a laser beam.

2. Method according to any one of the preceding claims, characterized in that the diaphragm (4) and the valve body (8) are welded together by means of the laser beam.

3. Method according to any one of the preceding claims, characterized in that the diaphragm (4) or the valve body (8) is provided with a heat-activatable adhesive.

4. Method according to any of the preceding claims, characterized in that the diaphragm (4) is fixed to the valve body (8) as a seam along the edge of the valve groove (5, 6, 7) by means of the laser beam.

5. Method according to any of the preceding claims, characterized in that the surface of the diaphragm (4) facing the valve spool (5, 6, 7) is heated by radiation incident on the diaphragm (4).

6. A method according to claim 5, characterized in that the radiation is incident on the surface (9) through the membrane (4).

7. A method according to claim 5 or 6, characterized in that the radiation is incident on the surface (9) through the valve body (8).

8. Method according to any one of the preceding claims, characterized in that the surface (9) of the valve body (8) is polished before the fixing.

9. Method according to any of the preceding claims, characterized in that the surface (9) of the valve body (8) is plasma etched before the fixing.

10. Method according to any of the preceding claims, characterized in that the surface (9) of the valve body (8) is etched by means of an ion beam before the fixing.

11. A method according to any of the preceding claims, characterized in that the surface (9) of the valve body (8) is smoothed by chemical modification before the fixing is performed.

12. Method according to any one of the preceding claims, characterized in that the surface (9) of the valve body (8) is subjected to a hydrophilization treatment before being fixed.

13. Method according to any of the preceding claims, characterized in that the surface (9) of the valve body (8) has an average roughness value (Ra value) of less than 100nm, preferably less than 50nm, particularly preferably less than 20nm, before being fixed around the valve spool (5, 6, 7).

14. Method according to any one of the preceding claims, characterized in that the pump is used for delivering liquid at a flow rate of between 0.01 μ L/h and 1ml/h, but in particular for delivering liquid at a flow rate of between 0.01 and 100 μ L/h, in particular in the range of 0.01 to 80 μ L/h.

15. Method according to any one of the preceding claims, wherein the pump is used for delivering liquid with a pump volume of between 5 nL/stroke and 1 μ L/stroke per pump stroke, but in particular for delivering liquid with a pump volume in the range of between 25 nL/stroke and 500 nL/stroke, in particular in the range of 75 to 250 nL/stroke.

16. Method according to any of the preceding claims, characterized in that the error in directing the laser beam in the x-y direction is larger than 0.05 micrometer and smaller than 1 millimeter, preferably smaller than 50 micrometer, especially preferred smaller than 5 micrometer.

17. Method according to any of the preceding claims, characterized in that different polymers with different transmission ranges are used for the diaphragm (4) and the valve spool (5, 6, 7), which polymers are welded by means of an ultraviolet laser, a visible laser beam or an infrared laser.

18. The method according to any of the preceding claims, characterized in that the wavelength of the laser beam is in the range between 0.1 and 1000 micrometer, preferably between 0.4 and 50 micrometer, particularly preferably between 0.78 and 3 micrometer.

19. Method according to any of the preceding claims, characterized in that the power of the laser beam is between 0.01 and 1000 watts, preferably between 0.1 and 100 watts, particularly preferably between 3 and 50 watts.

20. Method according to any one of the preceding claims, characterized in that the fixing is performed on a line having a width of 20 to 3mm, preferably between 30 and 500 microns, particularly preferably between 50 and 300 microns.

21. Welding device for carrying out the method according to one of the preceding claims, having a laser and a device for computer-controlled movement of the laser and having a digital camera for automatically capturing the start and end coordinates of the movement in order to weld the diaphragm (4) around all valve slots (5, 6, 7).

22. A tensioning device for implementing the method according to any one of the preceding claims, in order to tension the covering membrane/diaphragm (4) with correct pretensioning in a wrinkle-free manner flush with the valve top side in such a way that the pressure exerted by the membrane on the valve top side is the same everywhere, in order to achieve a uniform weld seam.

Disclosure of Invention

The present invention relates to a method for improving the dosing accuracy of microfluidic pumps and/or valves based on a flexible cover film called a diaphragm and a valve spool according to claim 1.

Advantageous further developments are found in the subject matter of the dependent claims.

It is therefore advantageous to weld the diaphragm and the valve body together by means of a laser beam. Furthermore, this diaphragm or valve body may be provided with a heat-activated adhesive. It is useful to fix the diaphragm to the valve body as a seam along the edge of the valve groove by means of the jet. The surface of this diaphragm facing the valve spool can be heated by radiation incident on the diaphragm. This is particularly easy when the radiation is incident on this surface through the membrane. However, it is also possible for radiation to pass through the valve body and be incident on this surface. In order to obtain a particularly smooth surface against which the diaphragm rests, the surface of the valve body may be polished before fixing. The surface of the valve body can be plasma etched before fixing, etched by means of an ion beam, smoothed by chemical modification and/or the surface of the valve body can be hydrophilized before fixing. In this case, it is intended that the surface of the valve body, before being fixed around the valve spool, has an average roughness value (Ra value) of less than 100nm, preferably less than 50nm, particularly preferably less than 20 nm. To determine this measurement, the surface is scanned over a defined measurement section and all height and depth differences of this surface are recorded. Subsequently, after calculating the constant integral of the roughness curve over the measurement section, this result is divided by the length of this measurement section.

This pump is used to deliver a liquid flow rate lower than 1 mL/h; but especially for transporting liquids at flow rates below 100 mul/h, especially at flow rates in the range of 0.01 to 80 mul/h. It is also advantageous for this pump to be used for delivering liquid with a pump volume of between 5 nL/stroke and 1 μ L/stroke per pump stroke, but in particular for delivering liquid with a pump volume of between 25 nL/stroke and 500 nL/stroke, in particular in the range of 75 to 250 nL/stroke. Reduced pump-to-pump delivery rate variations compared to pumps produced by thermal fusion with a heated bonding die are achieved by welding the topside of the valve pocket with the flexible diaphragm with a laser beam. The error in directing the laser beam in the x-y direction should be less than 1 mm, preferably less than 50 microns, and particularly preferably less than 5 microns. In order to be able to weld a cover film/diaphragm made of a transparent polymer to a valve groove also made of a transparent polymer, so that optical measurements can be made in different parts of the spectrum within the pump or in the environment of the pump, different polymers with different transmission ranges can be used, which are welded by means of an ultraviolet laser, a visible laser beam or an infrared laser. Preferred wavelength ranges for such lasers are between 0.1 and 1000 microns, preferably between 0.4 and 50 microns, particularly preferably between 0.78 and 3 microns. In this spectral range (near infrared), many polymers have characteristic absorption bands, and can therefore be heated at precisely defined positions beyond their softening point by a focused laser beam, without the use of other absorbers in the plastic or on the surface of the plastic (absorber-free transmission welding). Plastics with high transmission for visible light, such as polystyrene or ethylene-norbornene copolymers (COC or COP), can also be soldered without an absorber. The power of the laser beam is between 0.01 and 1000 watts, preferably between 0.1 and 100 watts, particularly preferably between 3 and 50 watts.

The advantage of welding the diaphragm membrane and the valve groove by means of a laser instead of thermally joining them by means of a joining die is that the laser can be better adjusted than with a heated joining die and that the welding process does not take place planar but is limited to the seam line, the geometry and course of which can be determined by accurately directing the laser with an x-y error of less than 3 μm. In this case, the width of this weld is less than 1 mm, preferably between 250 and 20 microns. Advantageously, the fixing is carried out on a line having a width of 20 micrometers to 3 millimeters, preferably between 30 and 500 micrometers, particularly preferably between 50 and 300 micrometers. By means of precise guidance of the laser and a small seam width, eccentricity of the valve seat, which is difficult to avoid when thermal bonding is carried out by means of a bonding die, is avoided and boundaries between the welded diaphragm film and the non-welded diaphragm film and sticking of the diaphragm film in the valve seat due to undesired welding are avoided.

However, the precise guidance of the weld seam and the associated low heat input into the valve spool does not always prevent the diaphragm membrane and the valve spool from adhering non-thermally. This applies in particular if the thickness of the valve membrane is greater than the depth of the valve groove or if the thickness of the valve membrane and the depth of the groove are at least similar in size. In this case, it is possible to press the pre-tensioned membrane onto the plastic chip, which is preferable for a firm welding, which results in the membrane also being pressed into the valve groove. Although the precise local guidance of the laser beam and the precise quantification of its power reliably prevent welding of the membrane in the valve groove, the hydrophilic interaction of the less polar surface of the valve groove in the plastic chip with the likewise less polar surface of the diaphragm membrane causes the membrane and the chip to adhere together. Possible electrostatic charges of the less conductive surface may also promote this adhesion. Furthermore, the valve spool surface may look like uneven sandpaper when viewed with a microscope of appropriate magnification, and the surface roughness of the valve spool may cause the relatively soft diaphragm film to catch with these sandpaper-like structures when pressed against the micro-roughness of the valve spool for the welding process. All the effects mentioned, alone or in combination, may cause an interaction between the diaphragm membrane and the valve spool, resulting in the pumping process being prevented. This may be manifested as a drop in pump power or a failure of the diaphragm pump. Unlike the side effect which often occurs in particular in thermal joining/welding with heated metal molds, i.e. accidental thermal welding of the valve housing and the membrane film, the interaction mentioned between the membrane and the film in the case of laser welding is at least partially reversible in nature. Thus, these interactions can be partially cancelled during the pumping process. Nevertheless, the strength with which the diaphragm membrane and the valve spool can interact is sometimes so great that appropriate countermeasures have to be taken.

A fundamentally simple way to reduce the mechanical interaction between the chip and the membrane film, which may be caused by the micro-roughness of the valve spool, is to smooth the surface of the valve spool. Since the chip with its valve gate is preferably produced by injection molding, it is proposed in particular to smooth the valve gate in an injection mold, which is in principle a convex structure that is easy to achieve, by polishing. This reduces the roughness to a fineness of a few nanometers. The interaction between the diaphragm membrane and the valve spool can thus be considerably reduced compared to the interaction produced by a chip whose corresponding injection mould is only subjected to milling and grinding. Although in principle very simple, the manual requirements for a fine polishing of the order of nanometers of injection molds made of metal (and sometimes of hard metal) are very high. The smoothness of the valve groove on the chip body is technically less demanding. Depending on the significantly softer material (mainly polystyrene, polyolefin or another plastic) used here, polishing the valve spool is simpler than polishing the injection mold-but at the cost of having to machine each single injected chip, not just a single mold. In addition to polishing, the surfaces in the valve pockets of the chip may also be chemically smoothed. For this purpose, it is preferable to use solvents which attack, to a limited extent, the polymers used to form the chip. This allows for smoothing fine structures, such as the particle size of the valve spool. For chips made of polyolefins, a mixture of Tetrahydrofuran (THF) and water (preferably a THF content of 5 to 70%) or a mixture of Methyl Ethyl Ketone (MEK) and water (preferably a MEK content of 5 to 25%) is used. For polystyrene, it is recommended to mix isopropanol with water. A mixture of a solvent that attacks the polymer used to make the valve spool and a solvent that the valve spool can resist should generally be used. This makes it possible to adjust the mixtures against which the valve spool is resistant rather than inert. This allows smoothing of the very fine structures that cause the roughness of the valve spool without significantly damaging the significantly coarser structures that represent the channels in the chip and the cavities of the valve spool. Solvent mixtures containing components immiscible with water may also be used to smooth the valve spool. Mixtures of chlorinated solvents, such as chloroform or dichloromethane, with ethanol or isopropanol are particularly suitable for smoothing the surface of polyolefins. The physicochemical process (e.g., plasma etching) may also flatten the valve pockets after injection molding or after milling the chip and valve separately. In this case, the chip with the valve is exposed to an oxygen plasma or air plasma generated by a high pressure in a vacuum (0.001 to 0.1 mbar). In this case, the fine roughness is subject to oxidation erosion and becomes smooth. In addition, the plasma causes the deposition of oxygen radicals on the polymer surface and the formation of oxidation products of the polymer. In this case, in particular, carboxylic acids, alcohols, aldehydes, ketones, epoxides, oxetanes, peroxides and other partially poorly characterized free radical oxygen adducts are produced. All of these connections result in a significant increase in surface polarity, except possibly smoothing the valve cavity surface. This reduces the hydrophobic interaction between the diaphragm membrane and the valve cavity, which in turn greatly reduces the adhesion between the valve and the membrane.

An equally very good way to reduce the interaction between the valve cavity and the membrane is to coat the inside of the valve with a polar compound. For this purpose, detergents are particularly suitable which, by means of a lipophilic substructure, firmly bond to the polymer surface of the valve spool and, by means of their polar head groups, reduce the adhesion of the valve membrane to the valve spool to virtually zero. For this purpose, anionic, cationic and neutral detergents are suitable. Advantageously, these detergents are applied from an aqueous solution of the detergents at a concentration of 0.001 to 1%. For this purpose, the chip with the valve wells is briefly (at least about one second) immersed in an aqueous solution of a detergent. In this case, the lipophilic ends of the detergent automatically orient on the chip/valve well surface and form a dense layer, with the polar head groups of the detergent facing the aqueous medium, from which the detergent in solution diffuses towards the chip/valve well. Detergents suitable for this purpose are classical soaps, i.e.basic salts of higher carboxylic acids, but especially polymeric carboxylic acids, for example polyacrylates (Sigma-Alrich), which, on account of their higher affinity, adhere more strongly to the surface of the chip or valve spool. Also suitable are sulfates or sulfonic acids, such as sodium dodecyl sulfate (SDS, Sigma-Aldrich) or polymeric analogs thereof. Higher molecular weight natural materials such as lecithin or chemically purified lecithin-like compounds (e.g. phospholipid G90, lipoid ag, cologne) have also proven particularly suitable. For these compounds, the anionic functional group is represented by a phosphate group. Suitable cationic polymers are quaternary ammonium salts having at least one higher alkyl group ("retro soaps"), such as tetradecyltrimethylammonium chloride. Here, like anionic polymers, the adsorption of the chip/valve spool can also be increased by using polymeric structures. Polyethyleneimine (Sigma-Aldrich) and higher molecular weight polyamines with or without quaternary amino groups have proven particularly suitable. Neutral detergents are also well suited for hydrophilic coatings on chip surfaces/valve wells. Besides low molecular compounds such AS Tween 20(Sigma-Alrich), also proven useful are the Suffynol series (e.g.Suffynol 61, Surfynol 104, Surfynol AD 01, Surfynol AS 5020, Surfynol AS 5040, Surfynol AS 5060, Surfynol AS 5080, Surfynol AS 5180) and Tegopren series (Tegopren 5840, Tegopren 5860, Tegopren 5885). Both Surfynol and Tegopren are available from Evonik of Essen. These compounds are partially soluble in water; it is partly suggested to coat microfluidic chips by first preparing a stock solution of neutral polymer at a concentration of about 10% in isopropanol and then diluting it with water to a target concentration of 0.001 to 1%.

The detergent coating of the valve edge, on which the membrane film should be welded, may lead to a reduced stability of the weld seam, and it is therefore advisable to avoid coating the valve edge or to reduce the thickness of the coating, or to not weld the membrane film, but to thermally bond it. In any case, very good quantifiability of the energy input and positioning accuracy of the laser can be used in the bonding, so that the hot-melt bonding process is preferred over conventional bonding.

One possible way to confine the detergent coating to the inside of the valve body (i.e. not to hydrophilically coat the entire chip surface) is to cover the valve areas on the chip by means of an adhesive tape perforated in the valve groove locations. Thus, during plasma processing of the chip, only the inside of the valve slot is exposed to oxygen or air plasma, while the valve edge is protected by the tape. The chip prepared in this way was immersed in the above-mentioned detergent solution so that only the inner side of the valve well was hydrophilically coated, and the hydrophilic coating on the valve edge was removed by peeling off the protective tape. So that, of course, welding can be carried out subsequently. The use of a detergent that preferentially binds to the plasma-activated portions of the surface rather than to portions that remain native allows the protective tape to be removed first after plasma activation, and then the entire chip to be treated with a detergent solution. Tegopren 5840 is particularly suitable for such processes-it primarily only bonds to the plasma-activated portions of the chip, thus allowing the chip to be subjected to a detergent treatment after removal of the protective tape without compromising the strength of the subsequent laser weld. This property of Tegopren 5840 and Surfynol AS50xx allows the use of a rigid cover mask, rather than an adhesive tape, which is easier to position, but only limited in positioning or not at all possible to handle with the chip in a detergent solution, to cover the valve edge during plasma activation. Other detergents (e.g., phospholipid G90) adhere to plasma-activated chips as well as non-plasma-activated chips, thus allowing hydrophilic coating without plasma activation.

For thermal bonding of the chips, a film coated with a heat-activated adhesive should be used. Coating the chip body with adhesive is only meaningful if during the coating process as little adhesive as possible, but preferably no adhesive at all, is noticed that can penetrate into the valve wells. This allows the use of adhesive directly on the chip body, but is relatively complex. Therefore, it is generally preferred to coat the film with an adhesiveCloth, rather than coating the chip body. For the laser-activated thermal bonding of the separator film and the chip, it is possible to use commercially available hotmelt films (e.g. MH-92824, 93025 or 92804; Adhesive Research, Dublin, Ireland) or polyolefin films coated with polyurethane-based hotmelt (films: Denz BioMedical GmbH, Austria;)) (ii) a Adhesive: dispercoll U53 was blended with 7.5% Desmodur Ultra DA-L, both produced by Covestro AG from Leverkusen). For bonding, the thickness of the membrane film should be 30 to 300 μm. Preferably about 100 μm. In this case, a suitable adhesive layer thickness is from 2 to 100 μm. Preferably about 7 μm thick. Due to the post-crosslinking of Dispercoll and Desmodur after laser assisted thermal bonding, the adhesive joint should be cured for at least 12 hours until the final strength is reached.

The invention also relates to a device in which the laser is moved in a computer-controlled manner by means of start and end coordinates automatically acquired by a digital camera in such a way that the cover film/diaphragm around all valves and pumps is welded in the correct position. The invention also relates to a tensioning device for the wrinkle-free tensioning of a cover film/membrane with correct pretension in such a way that the pressure of this film on the valve top side is the same everywhere, in order to achieve a uniform weld seam, flush with the valve top side. In the case of integration of a plurality or a large number of valve channels into a microfluidic chip, the tensioning device according to the invention makes it possible to tension the cover film/membrane without wrinkles in a flush manner with the top side of the chip with a correct pretension in such a way that the pressure which this film exerts on the chip surface is the same everywhere in order to achieve a uniform weld seam.

The invention further relates to a method and a device for the individual metering of small amounts of liquids or gases in microreactors and microreactor arrays (e.g. microtiter plates) using the described pumps and valves.

The drawings show embodiments, which will be described below. Wherein:

figure 1 is a microfluidic pump with multiple valves and empty valve pockets,

figure 2 is the pump of figure 1 with two filled valve spools,

figure 3 is the pump of figure 1 with a filled valve spool,

figure 4 is a tensioner for applying a diaphragm,

figure 5 is a side view of the welding device,

figure 6 is a top view of the welding device of figure 5,

figure 7 shows the position of the adjusting screw on the welding device of figure 5,

figure 8 is a top view of the position of the adjustment screw shown in figure 7,

figure 9 shows the position of the force sensor and locating pin on the welding device of figure 5,

figure 10 is a view of a vacuum chamber made of glass,

figure 11 is a cross-sectional view of the vacuum chamber of figure 10,

figure 12 is a valve profile without a weld seam,

FIG. 13 is a weld profile, an

FIG. 14 is a valve profile with a weld.

Fig. 1 to 3 show a pumping sequence of a plurality of microfluidic pumps 1, 2, 3, wherein a flexible membrane 4 covers valve slots 5, 6, 7 of a valve body 8. In order to fix the flexible membrane 4 to the valve body 8, the surface 9 of the membrane 4 facing the valve grooves 5, 6, 7 is heated by means of a laser beam. In the present case, the valve slots 5, 6, 7 are juxtaposed to one another, so that the diaphragm 4 is fixed to the valve body 8 only in the edge region 10.

In this embodiment, the valve body 8 is a microfluidic chip 11, over which a microtiter plate 12 is arranged. The reservoir 13 and the wells 14 are located in this microtiter plate 12. The microtiter plate 12 is moved by a rocking array 15 in which channels 16, 17, 18 of pneumatic devices acting on the membrane are arranged.

Fig. 2 shows how liquid flows from the reservoir 13 into the valve spools 5 and 6, and fig. 3 shows how the liquid in the valve spool 7 connects with the orifice 14.

Fig. 4 shows the piston table 20 with the positioning table 21 arranged above it, over which the diaphragm 22 is tensioned. The diaphragm 22 rests on a polymer matrix 23 and is held on both sides by magnets 24 and 25, which can be moved by a rail in the direction of the arrows 26, 27 in order to tension the diaphragm 22.

Fig. 5 shows an overall system of devices for welding valve or pump tanks and cover films/cover diaphragms: the welding device 30 contains a radiation source 31 (e.g. a thulium doped fiber laser), a shaft system with shafts 32 and 33 that allows the tensioning device to move in one plane under the laser, but at least in one direction, to thereby produce a weld with a defined position. This tensioning device itself allows at least one valve spool, but typically two or more valve spools or pump spools integrated in the chip/polymer matrix 37, to be secured to the movable shaft system. In addition, a transparent flexible membrane 38 is tensioned over the polymer matrix 37. This tensioning device consists of a cylinder 39 with a piston table 40, a positioning table 36, at least four adjusting screws 41 and at least four force sensors 42. The force sensor 42 allows an isotropic tensioning of the membrane by means of the tensioning mount 34. The tensioning device with the polymer matrix and the tensioning diaphragm is pressed against the glass plate 35 by lifting the piston table. This glass plate exerts pressure on the polymer matrix with the chip. The membrane and the polymer matrix are thermally softened or melted by applying the energy of a laser through a glass plate to the membrane tensioned over the polymer matrix. The pressure between the glass plate and the polymer matrix causes a material flow between the membrane and the polymer matrix, which, after solidification of the molten polymer, results in a narrow, precisely positioned and mechanically durable weld seam.

The polymer substrate is precisely aligned with the positioning table by means of a centering device, for example consisting of 2 positioning pins 43, which fit into corresponding mounting holes in the substrate, and thus brought into a fixed position (fig. 9). This positioning table rests on four force sensors 42 which are embedded in a piston table which is firmly connected to the cylinder. The four force sensors measure the forces applied to the four corners of the rectangular positioning table when the positioning table presses this polymer collectively from below against the glass plate 35 by means of a membrane tensioned over the polymer matrix. The force distribution can be adjusted by means of four screws 41a, 41b, 41c, 41d (fig. 7) at the respective corners, which are screwed into the positioning table 36. In this case, the screws reduce or increase the distance between the positioning table and the piston table, so that the pressing force is reduced or increased there, and an even distribution of the contact pressure over the entire polymer matrix can be ensured.

The radiation source 31 is positioned plane-parallel to the chip 37 at a distance from the specific focal position such that the focal point of the laser is located at or near the plane spanned by the polymer matrix and the film. The closer the focal point of the laser is to this plane, the narrower the weld and the lower the laser emission power. In this case, this focal position determines the energy input into the polymer body and the membrane film at the location to be welded, and thus the accuracy of the welding process. In this case, this focal position may be fixed or may be variably adjusted by means of a shaft system with shafts 32 and 33, which allows the laser to be moved perpendicular to the arrangement of the polymer matrix with the film.

In this case, the polymer body 37 and the diaphragm 44 are pressed from below by means of the cylinder 39 onto the glass plate 35, which has a high spectral permeability in the wavelength range of the laser. Especially in the wavelength range of 1940nm, glass is very suitable as material for pressing this polymer body onto the membrane film, since glass absorbs only minimal electromagnetic radiation in the near infrared range below the wavelength of 3 μm. The glass plate is held by a frame or tensioning support 34 and oriented parallel to the radiation source 31. The distance is also determined by the focal position of the laser on the polymer body 37.

The radiation source 31 can be moved parallel to the polymer matrix 37 by means of a system of axes with axes 32 and 33, so that this radiation source passes over the contour to be welded. In this case, the power and feed speed of the laser are variably adjustable.

The movement of the cylinder 39 relative to the radiation source 31 is achieved by at least two axes 32 and 33, which either move the cylinder 39 by means of a moving stage 45 or move the radiation source 31 in space.

The flexible membrane 44 may be tensioned in parallel to the microfluidic substrate 37 by a tensioning device.

This flexible membrane can be tensioned in different ways. In order to apply the film onto the glass plate as plane-parallel as possible, microchannels 46 can be etched into the glass plate 35 by selective laser etching (Meineke et al.2016) (fig. 10 by means of a vacuum chamber 47 made of glass), which allow a negative pressure to be generated in the channels by a connected vacuum pump, so that the flexible membrane is sucked onto the glass plate before the microfluidic substrate is pressed onto this glass plate (fig. 11). This reduces non-uniformities in the flexible film.

Another tensioning solution is to use magnets embedded in the piston table. The membrane is pre-tensioned by hand on the substrate and then held by other magnets of opposite polarity. In this case, the magnets are supported on a fixable rail that is movable in one direction in order to further stretch the membrane film and then fix it in the desired position (fig. 4). This improves the tightening accuracy.

Other tensioning solutions for the flexible membrane are the use of pneumatic cylinders. In this case, the membrane is fixed on one side (for example by means of a magnet), then tensioned on the base and fixed on the other side by means of a pneumatic cylinder; this cylinder is fixed to another orthogonally mounted cylinder so that the diaphragm can be stretched or tensioned further by extension of the cylinder in the x-direction with a defined force spread. Thereby creating uniform tension throughout the weld area.

The polymer matrix contains microstructures that collectively interact with the membrane film to form a plurality of pump and valve systems. A microfluidic array is formed by a plurality of valves, pump chambers and channels and inlets and outlets, which is capable of delivering a liquid or gas individually from a fluid inlet to a microreactor.

Such an array may be constituted by an actuation terminal block and a microreactor array with integrated microfluidic chips as described in european patent EP 3055065. This microfluidic chip consists of a valve made of a truncated sphere with concentric line seals and a flexible diaphragm. The micro-channel communicates with the center of the valve and opens up to the circumference of the truncated ball. This flexible diaphragm can be moved by an actuator and can be closed and opened.

Different methods can be used to control each diaphragm valve. Pneumatic control channels are particularly considered here, but optical, thermal, hydraulic, electromechanical or magnetically activated switches can also be used for the fluid channel control.

One solution is to create peristaltic motion in which fluid is first forced through an inlet into an open inlet valve and an open pump chamber. By subsequently closing these inlet valves, a precise volume of fluid is trapped in the pump chamber. By opening the outlet valve and closing the pump chamber, the volume of the pump chamber can be conveyed in the direction of the passage outlet (fig. 1 to 3). In this case, the volume delivered depends to a large extent on the precision of the pump chamber, which is created by the structure of the polymer body and the covering achieved by the membrane film. Multiple fluid passages can also be controlled by this technique through the inlet and pump chambers (fig. 11).

The described invention greatly improves the accuracy of valve coverage. First, the present invention reduces the variation in the volume enclosed by the valve spool and the cover film, thereby improving the accuracy of the quantification process. The mechanical principle is that laser transmission welding allows for a more precise geometry of the weld edge or seam. This is achieved by a strictly locally limited energy input and a softening of the substrate only at precisely defined locations or along precisely defined seams. This almost completely avoids undesired associated heat transfer outside the defined area, in particular the energy input into the pump/valve spool.

A polymer host (m2p-labs GmbH, Baesweiler, manufactured byThe finished MTP-MF32-BOH 1) was fixed on a positioning table as described above and the separator film (B)ELASTOMER E-140, 100 μm thick) was tensioned onto the areas to be welded. Fig. 2 shows an example of a valve profile before welding. The corresponding weld profile (e.g., the weld profile shown in fig. 13) is created by a CAD program (e.g., Autodesk AutoCAD). This welding profile may then be loaded into a welding program. The speed of travel of the individual spots, the radiation power and the position for activating and deactivating the laser can also be adjusted. The objects to be welded are then pressed onto the glass plate 35 by means of ｃA gas cylinder (Festo ADN-100-60-A-P-A) at ｃA pressure of 0.1 to 5 bar, preferably 0.75 bar. If the pressure is too high, this diaphragm membrane may deform and be pressed into the valve. If the pressure is too low, the flow of material within the weld is retarded, thereby reducing the strength of the weld. By reading these force sensors (ME-Messtechnik KM26), it is ensured that the force distribution is uniform, which otherwise has to be readjusted by means of an adjusting screw. The uneven force distribution may result in uneven focusing of the laser.

The welding can be performed using a thulium doped fiber Laser from "IPG Laser" with a wavelength of 1940 nm. This wavelength is suitable because the polymers used (COC, cycloolefin copolymers; copolymers of norbornene and ethylene) have an absorption in this wavelength range. Suitable optics with a focal length of 20mm will focus the laser beam. For the welding process, a laser power of 2 to 50W is required, depending on the feed speed in particular; the laser power is preferably 5 to 25 watts at a feed rate of the laser of 10mm/min to 2000mm/min, and particularly preferably 8 watts at a feed rate of 200 mm/min. The moderate Laser power required allows selection between a large number of lasers, such as the Thulium doped Fiber Laser (CW _ Laser CTFL-TERA) or the IPG Laser (TLM-200 Thulium CW Fiber Laser Module) from Keopsys.

Except COCIn addition, the method described here can also be used for other polymers which absorb in the infrared rangeA compound (I) is provided. Examples in this connection are polystyrene, polymethyl methacrylate, polycarbonate, polyethylene, etc.

The radiation source can be moved in the weld area in the x, y and z directions by an axial system (e.g. Bosch Rexroth linear system) to move the individual valves, channels and pump profiles at a speed of, for example, 200mm/min at a laser power of about 8W. In this case, the laser beam is activated only at the specified contour, so that an undesired energy input is avoided. This radiation source is positioned at a height of about 17mm relative to the surface of the polymeric body, with a focal length of 20 mm. This height has to be adapted by changing the focal length. In order to avoid melting the channel due to increased local energy input, the welding profile must be produced at a precise distance of about 0.3mm from the channel. Fig. 14 shows a valve profile with a weld.

The flexible membrane is softened only at the location where it is penetrated by the laser beam and joined to the base body by thermal fusion. The valve or channel profile is prevented from melting and the weld seam is defined by the higher travel speed of the radiation source. Variations in radiation power may further affect the seam. Thus, a higher accuracy of the valve profile can be achieved by a sufficient accuracy of the shaft system. This is directly reflected in the accuracy of the quantification process.

For measuring the accuracy of the flow, the microfluidic chip is glued as a bottom of a 48-well microtiter plate in a gas-tight and liquid-tight manner. The microtiter plate was placed on an orbital shaker which mixed the liquid in the microtiter plate at a rate of up to 1500UpM (revolutions per minute). The transparency of the polymer base or microfluidic chip allows optical measurements to be made of the liquid present therein in each individual reaction chamber. This enables, for example, the detection of the fluorescence signal of green fluorescent protein, fluorescein or riboflavin. This measuring device is realized in BioLector Pro from m2p-labs GmbH of Baesweiler, Germany.

To measure the flow rate, a mixture of 50mM aqueous buffer (K2HPO4) and 70. mu.M fluorescein was filled through the channel inlet of the microfluidic chip described in EP 3055065. Thus, by means of the optical waveguide, the corresponding optical filter with an excitation wavelength of 436nm and a detection wavelength of 540nm and the BioLector Pro analysis electronics of the company m2p-labs, it is also possible to detect a minimal change in fluorescence in the reaction chamber above the microfluidic plate. The fluorescein containing buffer solution is transported from the channel inlet in the reservoir well to the channel outlet in the reaction chamber by the actuator of the described pumping process. 800. mu.L of a buffer solution consisting of 50mM K2HPO4 was placed in the reaction chamber. Biolactor Pro has 16 reservoir wells and 32 reaction chambers. The solution can be transported from each reservoir well to four reaction chambers through the bottom of the microfluidic plate. If the same buffer solution containing fluorescein is filled into all reservoir wells and all pumps and valves in the microfluidic chip are controlled in the same manner, this fluorescein solution will be delivered to all 32 reaction chambers in the same manner. This arrangement allows to check whether all the pumps and valves that transport the fluorescein solution from the reservoir wells into the reactor vessel are transported equally and uniformly. This can be quantified in that the fluorescence intensity of fluorescein pumped from the reservoir well into the reaction chamber is measured at regular intervals in all the reaction chambers and the change in fluorescence over time is determined. This measurement can also be done fully automatically in biolactor Pro. With a pneumatic pressure of 0.5 bar, liquid is conveyed into the microfluidic channel via the inlet valve and the pump chamber until the outlet valve is reached. The inlet valve was closed at 2 bar. Opening the discharge valve allows the fluorescein solution to enter the corresponding reaction chamber. The liquid is transferred into the respective reaction chamber by closing the pump chamber at 2.5 bar. The discharge valve is then closed pneumatically at a pressure of 1.5 bar. This pumping process was repeated continuously in all 32 reaction chambers so that each reaction chamber produced a flow of 5. mu.L/h.

The change in fluorescence signal of all 32 reaction chambers of the microtiter plate was recorded over a period of about 20 hours. After the measurements were completed, the mean of the changes in fluorescence signal and the associated standard deviation and relative standard deviation were determined for all 32 measurements. If all microfluidic pumps in the chip are controlled in the same way, it is desirable that the flow rates in all 32 reaction chambers are the same and the standard deviation is correspondingly zero. Higher standard deviations reflect differences between these pumps or their controls, which can result in changes in flow rates.

This test was carried out several times with the aid of a microfluidic chip applied by thermal fusion and a microfluidic chip with a membrane film joined to a polymer matrix by laser welding. The results show that the precision of the pumping process is significantly improved and the standard deviation of the slope of the fluorescence signal is significantly reduced for microfluidic chips made by laser welding compared to microfluidic chips made by thermal fusion bonding. In the case of using a chip produced by heat fusion bonding, the relative standard deviation of the change in fluorescence signal with time averaged 12%; in the case of laser welded chips, this relative standard deviation is on average less than 7%.

The aforementioned claimed components to be used according to the invention as described in the embodiments are not subject to any special exceptions with respect to their size, shape, design, material selection and technical concept such that the selection criteria known in the field of application can be applied without limitations.