EP4157788A1

EP4157788A1 - Component with microfluidic structures, method for the production and use thereof

Info

Publication number: EP4157788A1
Application number: EP21719557.7A
Authority: EP
Inventors: Johannes Götz; Barbara Stadlober; Stephan RUTTLOFF; Dieter Nees
Original assignee: Joanneum Research Forschungs GmbH
Current assignee: Joanneum Research Forschungs GmbH
Priority date: 2020-06-02
Filing date: 2021-04-13
Publication date: 2023-04-05
Also published as: DE102020114621A1; WO2021244796A1; US20230191396A1

Abstract

The invention relates to a method for producing a component having a microfluidic structure, said method comprising the following steps: embossing depressions in an embossing lacquer layer, partially curing the embossing lacquer layer, sealing the depressions with a curable bonding lacquer layer and curing the partially cured embossing lacquer layer and the bonding lacquer layer. The invention also relates to a component obtainable according to said method and to the use of said component.

Description

Component with microfluidic structures. Manufacturing process and use

Field of invention

The present invention relates to a method for manufacturing a component with microfluidic structures, a component that can be manufactured using this method, and uses of the component.

State of the art

Components with microfluidic structures are typical elements in many sensor chips and contain microchannels and microchambers in which liquids can be received, passed on, mixed or otherwise processed. Examples of applications are biosensors for the rapid diagnosis of germs in hospitals or for the rapid analysis of chemicals in process technology, environmental analysis and the like. For most applications, the microfluidic structures are closed with a cover that contains inlet and outlet openings.

Microfluidic structures are usually manufactured using an injection molding process, in which a thermoplastic material is pressed into a mold while it is hot. The structures created in this way can then be connected using the known methods with a likewise thermoplastic cover layer or with a further thermoplastic microfluidic level. The disadvantages of the injection molding process are the high expenditure of time for injection and cooling processes, as well as the low throughput of the subsequent process steps, since the microfluidic chips have to be processed further as individual pieces.

An alternative way of producing microfluidic structures is a high-throughput production process in which the channels are produced on large polymer substrates in roll format. Using a roll-to-roll process, very large areas can be embossed in a short time.

Problems to be solved by the invention

In the prior art, however, no method is known with which the channels can be tightly closed with a cover layer in an efficient and simple manner in a method step after the embossing. It is therefore the object of the present invention to provide a simplified and efficient method which, in a roll-to-roll process, enables a firm connection between channel surfaces and their covers by UV crosslinking.

Summary of the invention

The object was achieved by providing the method, the component and the use according to the present invention and as defined in the claims.

The subject matter of the present invention is defined in particular in the following points [1] to [15] and [2-1] to [13-4]:

[1] Method for producing a component with a microfluidic structure, which comprises the following steps:

(a) the application of a layer of a curable embossing lacquer to a base film,

(b) the embossing of depressions in the embossing lacquer layer obtained in step (a) with an embossing tool,

(c) the partial hardening of the embossed lacquer layer in step (b) to form a partially hardened structural layer,

(d) removing the embossing tool with the formation of a base part which has the base film and the partially hardened structural layer,

(e) the application of a layer of a curable bonding varnish to a cover film to form a cover part, the thickness of the bonding varnish layer of the cover part being less than the embossing depth of the partially hardened structural layer of the base part formed in step (d),

(f) the formation of a composite of the bottom part obtained in step (d) and the cover part obtained in step (e), wherein the partially hardened structural layer of the bottom part is placed on the bonding lacquer layer of the top part, so that the recesses of the partially hardened structural layer of the bottom part of the bonding lacquer layer of the cover part are closed with the formation of cavities that form a microfluidic structure,

(g) the hardening of the partially hardened structural layer and the bonding lacquer layer of the composite obtained in step (f) with the formation of covalent bonds between these layers, the component being obtained with a microfluidic structure.

[2] Method according to [1], wherein the hardening in step (g) takes place via the polymerization systems contained in the partially hardened structural layer and the bonding lacquer layer, each of which contains polymerizable compounds with carbon-carbon double bonds. This means that CC double bonds are involved in the polymerization to form covalent bonds between the layers. It is possible to use polymerization systems which are based exclusively on compounds with CC double bonds or are thiol-ene systems.

[2-1] The curing in step (g) according to item [1] or [2] can preferably be carried out by UV irradiation. This means that the polymerization systems of the curable embossing lacquer and the curable bonding lacquer are UV-curable across layers.

The polymerizable compounds with carbon-carbon double bonds are preferably (meth) acrylate-containing compounds.

[3] Method according to [1] or [2] or [2-1], wherein the curable embossing lacquer and the curable bonding lacquer, independently of one another, each contain at least 50 percent by mass of a polymerisation system which, among polymerisable compounds with carbon-carbon double bonds and thiol- en systems is selected.

Here, "independently of one another" means that the curable embossing lacquer and the curable bonding lacquer can differ from one another in terms of the weight proportion of the polymerization systems. The structure of the compounds of the respective polymerization systems can also be different, as long as covalent bonds are formed between them and thus between the two layers during curing will.

The reactive groups are preferably the same in the curable embossing lacquer and the curable bonding lacquer, e.g. B. each vinyl groups. Even more preferably, not only the reactive groups, but the polymerizable compounds as a whole, that is to say the monomers or the oligomers, are the same.

[3-1] A combination of the features of [2] and [3] is preferred. [3-2] A combination of the features of [2], [2-1] and [3] is more preferable.

[4] Method according to one of the preceding points, wherein the curable embossing lacquer and the curable bonding lacquer have the same composition to an extent of at least 80, preferably at least 90 percent by mass.

At most 20, preferably at most 10 percent by mass of the curable embossing lacquer and the curable bonding lacquer can be different compounds, e.g. B. different initiators or reactive thinners.

The compositions can be the same not only with regard to the polymerizable compounds. It can also be preferred that the curable embossing lacquer and the curable bonding lacquer contain surface-active non-stick additives which are identical in structure and amount. [4-1] A combination of the features of [2] and [4] is preferred. [4-2] A combination of the features of [2], [2-1] and [4] is more preferable.

[5] Method according to one of the preceding points, wherein the curable bonding lacquer is not partially cured before step (g).

[6] Method according to one of the preceding points, wherein the cover part is arranged in such a way that the curable bonding varnish rests on the cover sheet by the action of gravity, or wherein the layer of the hardenable bonding varnish is selected so that it is without a covalent bond on the cover part adheres.

[7] Method according to one of the preceding points, wherein the partial curing in step (c) and the curing in step (g) take place by means of UV irradiation.

If necessary, the partial curing of the bonding lacquer layer after step (e) also takes place via UV curing. This means that the polymerization system can then be UV-curable both within the curable embossing lacquer and within the curable bonding lacquer as well as across layers.

[8] Method according to one of the preceding points, wherein the base film and the cover film are each a polymer film.

[8-1] The same polymer film as the bottom film and cover film is preferred.

[9] Method according to one of the preceding points, wherein after step (g) the hardened structural layer and the hardened bonding lacquer layer in the region of the cavities have the same thickness or a thickness that differs by a maximum of 20%.

[9-1] The same thickness is preferred. [9-2] A combination of the features of [9] with the feature that the bottom film and the cover film have the same thickness or a thickness different by a maximum of 20% is preferred. [9-3] A combination of the features of [8-1] and [9-1] is more preferable.

[10] The method according to any one of the preceding items, which is carried out in a continuous manner.

[10-1] In the method according to [10], a roll-to-roll method is preferably used for the embossing in step (b).

[11] The method according to [1], which is carried out in a continuous manner, wherein the base film and the cover film are each a polymer film, the curable embossing lacquer and the curable bonding lacquer have the same composition to at least 80 percent by mass, the curable bonding lacquer before step (g ) is not partially cured, the partial curing in step (c) and the curing in step (g) take place by means of UV irradiation and the thickness of the Bonding lacquer layer of the cover part is less than 20% of the depth of the depressions of the partially hardened structural layer of the bottom part.

[12] Method according to [1] or [11], the curable embossing lacquer and the curable bonding lacquer each contain at least 50 percent by mass of polymerizable compounds with carbon-carbon double bonds, the hardening in step (g) via polymerizable compounds with carbon-carbon double bonds takes place in the partially cured structural layer and the bonding lacquer layer and the curable embossing lacquer and the curable bonding lacquer have the same composition to at least 80 percent by mass.

[13] Component with a microfluidic structure, obtainable by a method according to one of points [1] to [12].

[13-1] The bonding lacquer layer in the component according to [13] is preferably not embossed. [13-2] The bonding lacquer layer in the component according to [13] or [13-1] preferably has a thickness of less than 1 μm. [13-3] The bonding lacquer layer in the component according to [13] or [13-1] preferably has a thickness of less than 1 μm and the structural layer has a thickness of at least 5 μm, preferably at least 10 μm. [13-4] In a preferred embodiment of [13] to [13-3], the composition of the structural layer differs from the composition of the bonding lacquer layer and the bonding lacquer layer is partially located in the depressions of the structure layer.

This difference can, for example, be based solely on the fact that the structure layer and the bonding lacquer layer differ from one another in terms of the content of surface-active anti-stick additive, the bonding lacquer layer, for example, not containing any surface-active anti-stick additive. Likewise, the difference can be based solely on the fact that with the same content of surface-active non-stick additives, these are arranged differently due to the embossing on the surface of the structural layer than on the surface of the unembossed bonding lacquer layer, which leads to different surface properties.

[14] Component with a microfluidic structure according to one of the items [13] to [13-4], the polymer of the structural layer and the polymer of the bonding lacquer layer being at least 80 percent by mass identical. More preferably the polymers are 100 percent by mass identical. In other words, at least 80 or 100 percent by mass of the polymers are based on identical monomer units, which in the case of copolymers can of course be arranged randomly. The polymers preferably each make up at least 80 percent by mass of the total layer. In a particular embodiment, the structure layer and the bonding lacquer layer can be completely identical, that is to say not only with regard to the polymers, but also with regard to any additives that may be present. [15] Use of the component with a microfluidic structure according to one of the items [13] to [14] as a biosensor, in the diagnosis of germs, environmental analysis or the analysis of chemicals in process engineering.

The present invention also relates to the following aspects [1] to [14] and [4-1] to [12-6]:

(a) the application of a layer of a curable embossing lacquer to a base film,

[2] Method according to [1], wherein the curable embossing lacquer and the curable bonding lacquer have the same composition.

[3] Method according to one of the preceding aspects, wherein the curable bonding lacquer is not partially cured before step (g).

[4] Method according to one of the preceding aspects, wherein the cover part is arranged such that the curable bonding lacquer rests on the cover film by the force of gravity, or wherein the layer of the curable bonding lacquer is selected, in particular so thin, that it is without covalent Connection adhered to the cover part. [4-1] A combination of the features of [3] and [4] is preferred, with it being more preferred that the layer of the curable bonding varnish is so thin that it adheres to the cover part without a covalent bond.

[5] Method according to one of the preceding aspects, wherein the partial curing in step (c) and the curing in step (g) take place by means of UV radiation.

[5-1] A method according to [5] is preferred, in which the embossing lacquer and the bonding lacquer contain (meth) acrylate groups or thiol-en systems which can be polymerized by means of UV radiation.

[6] Method according to one of the preceding aspects, wherein the base film and the cover film are each a polymer film.

[6-1] The same polymer film as the bottom film and cover film is preferred.

[7] Method according to one of the preceding aspects, wherein the thickness of the bonding lacquer layer of the cover part is less than 20% of the depth of the depressions of the partially cured structural layer of the bottom part. The thickness of the bonding lacquer layer of the cover part is preferably [7-1] less than 10%, more preferably [7-2] less than 5% of the depth of the depressions of the partially hardened structural layer of the bottom part. For example, the bonding lacquer layer has a thickness of less than 1 μm.

[8] The method according to any one of the preceding aspects, wherein the base film and the cover film have the same thickness or a thickness that differs by a maximum of 20%.

[8-1] The same thickness is preferred.

[9] Method according to one of the preceding aspects, wherein after step (g) the hardened structural layer and the hardened bonding lacquer layer in the region of the cavities have the same thickness or a thickness which differs by a maximum of 20%. [9-1] The same thickness is preferred. [9-2] A combination of the features of [8] and [9] is preferred. [9-3] A combination of the features of [8-1] and [9-1] is more preferable.

[10] Process according to one of the preceding aspects, which is carried out in a continuous manner. [10-1] In the method according to [10], a roll-to-roll is preferred for the embossing in step (b)

Roll method used.

[11] The method according to [1], which is carried out in a continuous manner, wherein the curable embossing lacquer and the curable bonding lacquer have the same composition, the curable bonding lacquer is not partially cured before step (g), either the cover part so is arranged so that the curable bonding lacquer rests on the cover sheet by gravity, or the layer of the curable bonding lacquer is selected, in particular so thin, that it adheres to the cover part without a covalent bond, the partial curing in step (c) and the curing take place in step (g) by means of UV irradiation and the thickness of the bonding lacquer layer of the cover part is less than 20% of the depth of the depressions of the partially cured structural layer of the bottom part.

[11-1] It is preferable to restrict the features from [11] to [7-1]. [11-2] It is preferable to restrict the features from [11-1] to [5-1].

[12] The method according to [1] or [11], wherein the bottom film and the cover film have the same thickness or a thickness that differs by a maximum of 20% and wherein, after step (g), the hardened structural layer and the hardened bonding lacquer layer in the region of the cavities have the same thickness or a thickness that differs by a maximum of 20%.

[12-1] A restriction of the features from [12] to [9-3] is preferred. Particularly preferred are: [12-2] combinations of the features of [12] and [11-1]; [12-3] combinations of the features of [12] and [11-2]; [12-4] combinations of the features of [12-1] and [11]; [12-5] combinations of the features of [12-1] and [11-1]; [12-6] Combinations of the characteristics of [12-1] and [11-2]

[13] Component with a microfluidic structure, obtainable by a method according to one of the above aspects [1] to [12] and [4-1] to [12-6]

[14] Use of the component with a microfluidic structure according to [13] as a biosensor, in the diagnosis of germs, environmental analysis or the analysis of chemicals in process engineering.

Advantages of the invention

The microfluidic structures of the components according to the invention are tightly and hermetically sealed all around due to the covalent bond between the cover and the side walls. As a result, the microfluidic structures are mechanically stable and insensitive to pressure differences and stresses during handling. At the same time, the structure of carrier foils and thin lacquer layers results in a high mechanical flexibility, which enables production in cost-effective roll processes. The microfluidic structures are also closed without the use of an adhesive, so that possible contamination is avoided.

Since the microfluidic structures can consist of the same material all round, the liquids or analytes can be transported more evenly and without interference. By suitable selection of the thicknesses of the substrate films, the embossing depth and the thickness of the bonding layer, an improvement in the mechanical stability can be achieved if the neutral mechanical plane is shifted or placed exactly in the interface between the bonding layer and the structure layer. This reduces mechanical loads in the event of stretching, compression or bending.

The method according to the invention enables simple UV bonding and can thus be used in high-throughput processes. Significant cost reductions are therefore possible compared to injection molding processes.

In contrast to thermal bonding, UV bonding creates a covalent bond. Since no thermoplastic behavior is required for UV bonding, there is no restriction to monofunctional acrylates, so that there is more freedom in material development.

Due to the formation of cross-links during hardening, the channel materials are elastic, so that the formation of cracks during roll-based production or in use is avoided.

Embodiments of the invention

The component according to the invention contains at least one microfluidic structure that is sandwiched between two substrate films. The microfluidic structure has dimensions on the micrometer scale in the z-direction and either in the x-direction or the y-direction, the x-y plane being defined by the surfaces of the substrate films. The microfluidic structure has, for example, a depth (in the z direction) and width (x or y direction) of 0.1 to 200 μm, preferably 1 to 50 μm, in each case. The microfluidic structure is suitable for receiving and transporting fluids, i.e. gases or liquids.

If the singular is used to designate elements or structures in the present invention, for example "a microfluidic structure" or "the microfluidic structure", a plurality of these elements or structures is expressly not intended to be excluded, so that the exemplary designations are synonymous with " at least one microfluidic structure "or" the at least one microfluidic structure ", unless stated otherwise.

The microfluidic structure is tightly closed all around. The expression “all around” in relation to the cover means here that a microfluidic structure is closed at every point in the z-direction, that is, in the direction perpendicular to the substrate film plane, and in the x-direction or y-direction. There is a microfluidic structure at every point So there is a cross-sectional plane in the y-direction in which the microfluidic structure is completely closed. The microfluidic structures have at least one opening, preferably at least one inlet opening and at least one outlet opening, at one of their ends in the xy plane. The term “solid” means here that the cover of a microfluidic structure cannot be peeled off in a non-destructive manner, for example by heating. In the present invention, the basis for the firm cover is the covalent bond between the starting structures.

The firm closure of the microfluidic structures is achieved in that the surfaces of the elements are chemically bonded to one another, i.e. covalently bonded. This creates a layer structure with an embedded microfluidic structure that can no longer be separated into the individual parts.

A hermetic seal also prevents the ingress of foreign substances and impurities that could falsify the analysis result and also allows temperature-controlled processes (e.g. on-chip PCR) to run.

The microfluidic structures are sealed with hardened embossing lacquer and hardened bonding lacquer. This means that the bottom, the side walls and the cover consist exclusively of these hardened paints. This formation excludes other substances, for example an adhesive between the bottom part and the cover part.

The curable embossing lacquer and the curable bonding lacquer

The curable embossing lacquer and the curable bonding lacquer can be the same or different from one another. The term “lacquer” used in the present application relates both to the curable embossing lacquer and, independently thereof, to the curable bonding lacquer, unless otherwise stated.

The lacquer can be hardened, for example thermally or through the use of UV rays or electron beams. Curing with UV rays is preferred. The lacquer preferably contains at least one compound with polymerizable C-C double bonds. The compound can be selected from the group consisting of acrylates, methacrylates, vinyl ethers, allyl ethers, propenyl ethers, alkenes, dienes, unsaturated esters, allyl triazines, allyl isocyanates and N-vinyl amides. (Meth) acrylates are preferred. Acrylate-containing compounds can be selected from the group consisting of urethane acrylates, vinyl acrylates, epoxy acrylates, polyester acrylates, polyacrylates, polyether acrylates and polyolefin acrylates. Urethane acrylates are preferred. In addition to the compound with polymerizable C-C double bonds, the lacquer can also contain thiol-containing compounds.

Suitable UV-crosslinkable lacquers are based, for example, on polyethylene glycol diacrylates (PEGDA), optionally with 1-10 percent by mass of higher-functional acrylates, such as trimethylolpropane triacrylate (TMPTA) or pentaerythritol tetraacrylate (PETTA) or Mixtures of acryloyl morpholine (ACMO) with 10 - 50 percent by mass of higher-functional acrylates, such as trimethylolpropane triacrylate (TMPTA) or pentaerythritol tetraacrylate (PETTA), or coating systems based on highly crosslinking multifunctional polyether, polyester or polyurethane-acrylate systems, for example polyether polyol ethoxylated trimethylolpropane triacrylates or multi-ethoxylated bisphenol A diacrylates.

Polyethylene glycol diacrylates, trimethylolpropane triacrylate, acryloylmorpholine, pentaerythritol tetraacrylate, hexanediol diacrylate and trifunctional urethane acrylate oligomer are preferred.

In the present invention, a compound component designated by the term “acrylic” always also includes the derivative “methacrylic”, unless stated otherwise. For example, the “acrylate” group should also cover the “methacrylate” group.

In the present invention, UV-crosslinkable acrylate paints are particularly preferred. They are easy to process in a roll-to-roll process, as they do not require any pre-processes (prebake such as SU8) and are networked very quickly (in less than 1 s). They are also very easy to adjust with regard to their surface energy and thus their wetting properties, which play an essential role in capillary-driven microfluidics.

The lacquer can contain 0.05 to 5 percent by mass of photoinitiators which cause crosslinking under UV radiation, for example photoinitiators based on acylphosphine oxides, or oligomeric polyfunctional alpha hydroxy ketones or monomeric alpha hydroxy ketones.

Particularly suitable photoinitiators are, for example, photoinitiators on the basis of acyl phosphine oxides, such as Irgacure 819 ^®, Genocure ^® TPO, Genocure ^® BAPO or oligomeric polyfunctional Alphahydroxyketone as Esacure KIP 150 ^®, monomeric Alphahydroxyketone such as Irgacure 184, or Darocure 1173 ^®. However, mixtures of these photoinitiators can also be used.

Bottom sheet and cover sheet

The bottom foil and the cover foil are substrate foils, that is to say carrier foils, for the embossing lacquer or the bonding lacquer. They can be selected independently of one another and can be the same or different. Both substrate films are preferably flexible.

The substrate films preferably have a thickness of 5 to 2000 mhh, preferably 10 to 1000 mhh, particularly preferably 20 to 500 mhh. It is preferably a plastic film made of PI, PP, MOPP, PE, PPS, PEEK, PEK, PEI, PSU, PAEK, LCP, PEN, PBT, PET, PA, PC, COC, POM, ABS, PVC, PTFE, ETFE (ethylene tetrafluoroethylene), PTFE (polytetrafluoroethylene), PVF (polyvinyl fluoride), PVDF (polyvinylidene fluoride), and EFEP (ethylene tetrafluoroethylene hexafluoropropylene fluoroterpolymer).

Additives

The embossing lacquer and the bonding lacquer can contain additives independently of one another. Examples of such additives are surface-active anti-stick additives and reactive thinners.

(i) Surface active non-stick additive

In order to reduce the adhesion of the embossing lacquer to the embossing tool and to make it easier to remove the embossing tool after embossing, a surface-active non-stick additive, which can contain silicone or fluorine, can be added to the embossing lacquer used as the starting material. In particular, the additive is at least one member selected from the group comprising silicone-containing or fluorine-containing additives. Specific examples are nonionic surfactants such as polyether siloxanes, fatty alcohol ethoxylates such as polyoxyethylene (9) lauryl ethers, monofunctional polydimethylsiloxane (meth) acrylates, perfluoro-n-alkyl (meth) acrylates and perfluoropolyether (meth) acrylates. Silicone-containing or fluorine-containing additives contribute to reducing the adhesion and to facilitating the detachment of the embossing lacquer from the embossing tool, the perfluorinated additives in particular having proven to be particularly favorable and reliably enabling a plurality of replicas of a pattern. The at least one additive can be contained in the starting lacquer in an amount of 0.1 to 3% by weight.

After the method according to the invention has been carried out, the mentioned anti-stick additives can be contained at least partially in the embossed structural layer, for example in an amount of 0.1 to 3% by weight.

The adhesion of the embossing lacquer to the embossing tool can also be prevented by modifying the hydrophobicity of the surface of the embossing tool, in particular of the embossing die.

(ii) reactive diluent

A reactive thinner can be contained in the embossing lacquer and / or the bonding lacquer. A reactive thinner contains low molecular weight compounds to adjust the viscosity of the paint. Preferred reactive diluents are aliphatic (meth) acrylates or polyether (meth) acrylates, in particular HDDA or TMP (EO) xTA, for example TMP (EO) 9TA, TMP (EO) 6TA, TMP (EO) 3TA or TM PTA. The embossing lacquer layer and the bonding lacquer layer

The term “lacquer layer” used in the present invention relates to both the layer of a curable embossing lacquer and the layer of a curable bonding lacquer. The lacquer layer comprises or consists of a lacquer.

The lacquer layer is flat with dimensions in the x and y directions, which defines the contact plane with the substrate film, and in the z direction, which indicates the thickness of the layer. The term “thickness” of a layer here always means the extent perpendicular to the plane of the layer.

The lacquer layer material is applied to a substrate film. The fact that the lacquer layer material is not hardened, ie not polymerized, it has a low viscosity, so that it can be used, for. B. can be applied by painting or by pouring. It is preferably applied by means of gravure printing or slot nozzle coating.

The viscosity is adjusted so that the material can be easily applied. On the other hand, it has to be so viscous that the structure formed during embossing is retained. In order to meet both requirements, the material applied to the carrier can initially be irradiated moderately so that partial hardening and thus an increase in viscosity takes place. The lacquer may already be solid after partial curing, but it has unreacted reactive groups. The paint layer material preferably has the desired low viscosity at room temperature. As a result, the paint layer material can be applied at low temperatures, such as room temperature.

The embossing lacquer layer has a thickness, that is to say an extent perpendicular to the contact surface with the substrate film, of preferably 100 nm to 1000 μm, more preferably 1 μm to 100 μm.

In individual embodiments, the thickness can be 1 μm to 50 μm.

The bonding lacquer layer is in any case thinner than the embossing lacquer layer and preferably has a thickness of less than 5 μm, more preferably less than 1 μm.

A preferred combination is an embossing lacquer layer with a thickness of 1 pm to 100 pm and a bonding lacquer layer with a thickness of less than 1 pm.

The bonding lacquer layer is preferably not embossed. This means that the bonding lacquer layer has not been embossed before the assembly of the base part and cover part was formed. When the composite is formed, the bonding lacquer which is not or is only partially cured can be partially pressed into the depressions in the structural layer of the base part. This resulting structural change in the bonding lacquer should not be understood as embossing in the sense of the invention. The manufacturing process

Step (a):

The application of a layer of a curable embossing lacquer to a base foil is carried out, for example, with a roll-to-roll process in which the lacquer layer is applied to the substrate foil, for example by means of a slot nozzle or by gravure printing with a gravure roller.

Step (b):

The embossing of depressions in the embossing lacquer layer obtained in step (a) with an embossing tool takes place in at least a partial area of the embossing lacquer layer and comprises the formation of a recess in the plane of the embossing lacquer layer.

Embossing is done with an embossing tool, e.g. B. a punch, and can be implemented using a cylindrical punch in a continuous roll-to-roll process.

Ultraviolet nanoimprint lithography (UV-NIL for short) can be used, in which a nanostructured stamp with the inverted profile of the desired structure is used as a negative form and pressed into the embossing lacquer, in which the desired structure is then used as a Positive form is embossed. A preferred method according to the invention is a high-throughput production method (roll-to-roll UV-NIL) for microfluidic structures, in which the channels and chambers are produced on large polymer substrates in roll format.

The depth of the embossing, i.e. the extent of the depression in the z-direction, can be 1 to less than 100% of the thickness of the embossing lacquer layer. Preferably it is 50 to less than 100%, more preferably 80 to less than 100% of the thickness of the embossing lacquer layer.

Step (c):

The extent of the partial hardening of the embossing lacquer layer embossed in step (b) is set so that on the one hand a sufficient amount of reactive groups remains for the later hardening and connection with the bonding lacquer and on the other hand sufficient partial hardening takes place in order to achieve the required stability of the structures for demolding and Ensure winding. To this end, the following parameters are optimized: polymerization rate of the embossing lacquer (in particular the type and content of the photoinitiator), UV intensity, web speed, transmission of the substrate film. Step (d):

After the embossing and partial hardening, the embossing tool is removed. In order to facilitate this step and to increase the quality of the embossing, surface-active non-stick additives can be added to the embossing lacquer used in step (a).

Steps):

The application of a preferably very thin bonding lacquer layer to a cover film is preferably carried out by means of roll-to-roll gravure coating. The thickness of the cover layer should be as small as possible in order to enable faster curing in step (g) and to prevent the depressions from becoming blocked when the composite is formed in step (f). If the cover layer is too thick, in step (f) the still liquid material can flow into the depressions of the structure layer or be pressed before the surfaces and layers are chemically hardened, that is to say covalently connected. For example, the bonding lacquer layer has a thickness of less than 1 μm. A thickness of the bonding lacquer layer in the nanometer range also increases the flexibility of the component.

Since the embossing lacquer for the application in step (a) is preferably thin and, in a preferred embodiment, the composition of the embossing lacquer and the bonding lacquer is the same, the bonding lacquer is also thinly liquid during the application in step (e). In this case, it may be preferred or necessary that the cover part is arranged in such a way that the bonding lacquer layer lies on top of the cover film under the action of gravity, since otherwise the thin-liquid bonding lacquer layer cannot be guaranteed to remain on the cover film until lamination step (f) can. In a preferred embodiment, however, the bonding lacquer adheres to the cover layer independently of the effect of gravity and is based on non-covalent adhesion. This adhesion is achieved by adjusting the surface energies of the cover film and the bonding varnish, by selecting a suitable bonding varnish material and / or in particular by using a thin layer of the bonding varnish.

In order to make the bonding lacquer layer more viscous and, if necessary, to bond it covalently to the cover film, it can be partially cured. However, this leads to less adhesion after curing in step (g).

Step (f):

The composite can be formed by lamination, welding or bonding.

With the exception of the indentations of the embossing, the embossed side of the structural layer is covered over the entire surface and directly by the bonding lacquer layer of the cover part. In the depressions of the embossing there is preferably neither embossing lacquer nor bonding lacquer, so that cavities are created. The bottom membrane, the structural layer, the The lacquer layer and the cover film form a sandwich-like composite with external substrate films.

The expression “directly” means that no further material, for example an adhesive, is present between the lacquer layer and the cover layer. Only cavities forming microfluidic structures can be located between the structural layer and the bonding lacquer layer.

Step (g):

In the component according to the invention, the structural layer and the bonding lacquer layer are completely hardened, that is to say polymerized and crosslinked. This complete curing takes place in step (g). The curing is preferably a photopolymerization and is carried out by

Exposure to radiation. This radiation is preferably light of a suitable wavelength, for example UV light. The radiation dose is so high that complete polymerisation of the starting material is ensured. An overdose is preferably used to ensure that the cure is complete. In the present invention, the partial hardening in step (c) and the hardening in step (g) can be carried out in the same or different ways, the same way being preferred. Partial hardening and hardening can take place independently of one another, thermally or by using UV rays or electron beams. The partial curing in step (c) and the curing in step (g) are preferably carried out by UV irradiation.

Claims

1. A method for producing a component with a microfluidic structure, which comprises the following steps:

(a) the application of a layer of a curable embossing lacquer to a base film,

2. The method according to claim 1, wherein the hardening in step (g) takes place via the polymerization systems contained in the partially hardened structural layer and the bonding lacquer layer, each of which contains polymerizable compounds with carbon-carbon double bonds.

3. The method of claim 1 or 2, wherein the curable embossing lacquer and the curable bonding lacquer, independently of one another, each contain at least 50 percent by mass of a polymerization system selected from polymerizable compounds with carbon-carbon double bonds and thiol-en systems.

4. The method according to any one of the preceding claims, wherein the curable embossing lacquer and the curable bonding lacquer have the same composition to at least 80 percent by mass.

5. The method according to any one of the preceding claims, wherein the curable bonding lacquer is not partially cured before step (g).

6. The method according to any one of the preceding claims, wherein the cover part is arranged so that the curable bonding lacquer rests on the cover film by the action of gravity, or wherein the layer of the curable bonding lacquer is selected so that it adheres to the cover part without a covalent bond .

7. The method according to any one of the preceding claims, wherein the partial curing in step (c) and the curing in step (g) take place by means of UV irradiation.

8. The method according to any one of the preceding claims, wherein the bottom film and the cover film are each a polymer film.

9. The method according to any one of the preceding claims, wherein after step (g) the hardened structural layer and the hardened bonding lacquer layer in the region of the cavities have the same thickness or a thickness that differs by a maximum of 20%.

10. The method according to any one of the preceding claims, which is carried out in a continuous manner.

11. The method according to claim 1, which is carried out in a continuous manner, wherein the bottom film and the cover film are each a polymer film, the curable embossing lacquer and the curable bonding lacquer have the same composition to at least 80 percent by mass, the curable bonding lacquer before step (g) not is partially hardened, the partial hardening in step (c) and the hardening in step (g) take place by means of UV radiation and the thickness of the bonding lacquer layer of the cover part is less than 20% of the depth of the depressions of the partially hardened structural layer of the base part.

12. The method according to claim 1 or claim 11, wherein the curable embossing lacquer and the curable bonding lacquer each contain at least 50 percent by mass of polymerizable compounds with carbon-carbon double bonds, the curing in step (g) via polymerizable compounds with carbon-carbon double bonds in the partially cured structural layer and the bonding lacquer layer takes place and the curable embossing lacquer and the curable bonding lacquer have the same composition to at least 80 percent by mass.

13. Component with a microfluidic structure, obtainable by a method according to one of claims 1 to 12.

14. Component with a microfluidic structure according to claim 13, wherein the polymer of the structural layer and the polymer of the bonding lacquer layer are identical to at least 80 percent by mass.

15. Use of the component with a microfluidic structure according to claim 13 or 14 as a biosensor, in the diagnosis of germs, environmental analysis or the analysis of chemicals in process engineering.