Method for producing a microfluidic component, and microfluidic component

Abstract

The invention relates to a method for producing a ceramic microfluidic component, wherein, in a method step, a main body of the microfluidic component to be produced is shaped by primary shaping from a ceramic material so as to have a plurality of fluid structures, for example media ports, indentations and / or openings, wherein in particular the main body having the macroscopic fluid structures is formed substantially completely from the ceramic material, wherein, in an additional method step, microscopic microfluidic structures, in particular capillary structures or channels, are formed in the main body by means of a laser machining method and / or by means of a mechanical method.

Description

[0001] Method for producing a microfluidic component and a microfluidic component

[0002] The invention relates to a method for producing a microfluidic component for microfluidic systems.

[0003] The LOAC (Lab-on-a-Chip) method has been established for cell culture studies, drug research, rapid medical tests, chemical processes and analyses, and other applications involving sample volumes in the picoliter and microliter range. A LOAC is a microfluidic system in which virtually all the laboratory equipment required for a specific application, including reactors and tubing, is housed on a microscale chip approximately the size of a credit card. The transport of samples between the various reaction and analysis chambers can be achieved using capillary forces.

[0004] Lab-on-a-chip devices enable the functional integration of microfluidics into the diagnostic process. These devices or systems are small and less expensive than large laboratory systems. This allows them to be used directly at the point of care or integrated into other, larger systems.

[0005] For the production of LOAC systems, depending on the intended use

[0006] Plastics such as polydimethylsiloxane, polymethyl methacrylate, polycarbonate, polystyrene, cycloolefin polymers and cycloolefin copolymers,

[0007] Glass, such as photo-structurable lithium silicate glass, quartz glass and

[0008] Silicon is used.

[0009] LOAC microfluidic systems made of plastics are primarily manufactured using injection molding.

[0010] This allows for the production of complex components. However, the use of plastic components is subject to material-related limitations, particularly with regard to thermal limits, chemical resistance, and mechanical strength.

[0011] LOAC microfluidic systems made of glass are manufactured by selective etching with hydrofluoric acid. Glass plates are used as the starting material. Silicon-based LOAC microfluidic systems are fabricated from silicon wafers using photolithography and hydrofluoric acid etching.

[0012] Depending on the intended use, certain LOAC microfluidic systems also integrate media ports (interfaces for introducing a liquid medium into the microfluidic system) and other functional components such as micropumps and microvalves.

[0013] However, microfluidic systems manufactured in this way have disadvantages depending on the manufacturing method. Plastic-based microfluidic systems have limited stability towards organic solvents and can only be used up to approximately 100 °C. The thermal conductivity, which is important for controlling chemical processes, can only be achieved at low maximum values.

[0014] Due to the low mechanical strength, exposure of such systems to high media pressures is only possible to a limited extent.

[0015] Microfluidic systems based on glass or glass ceramics and silicon are difficult to manufacture in terms of molding technology and require high manufacturing costs and the use of toxic chemicals.

[0016] The object of the invention is therefore to propose a microfluidic component for a microfluidic system that eliminates the disadvantages of the prior art. In particular, the object of the present invention is to produce complex-shaped microfluidic system components made of ceramic materials simply and cost-effectively, without the aforementioned disadvantages.

[0017] The problem is solved by means of the characterizing features of the first claim. Further advantageous embodiments of the invention are claimed in the subclaims.

[0018] A method for producing a microfluidic component is proposed, wherein in one method step a base body of the microfluidic component to be produced is formed with at least one macroscopic fluid structure from a ceramic material by primary shaping, wherein the base body with the macroscopic fluid structures is formed substantially completely from the ceramic material, wherein in a further method step microscopic fluid structures are introduced into the base body by means of a laser processing method and / or by means of a mechanical processing method.

[0019] By primary shaping of ceramic pressing and injection molding materials with simultaneous introduction of macroscopic fluid structures in the range of a few millimeters to a few centimeters in average width and depth, sintering of the base body thus produced, subsequent (optional) precision machining of the surfaces and subsequent introduction of the microscopic microfluidic structures in the range of a few micrometers to a few hundred micrometers in average width and depth by laser processing or mechanical machining processes, it is possible to produce microfluidic systems while avoiding the disadvantages of the known processes.

[0020] Macroscopic fluid structures include, in particular, media ports, recesses, and / or apertures, without the invention being limited thereto. Microscopic fluid structures include, for example, capillary structures or channels.

[0021] By introducing macroscopic fluid structures into the initial shape, subsequent laser or mechanical processing can be limited to laser microstructuring or microscopic mechanical processing. This eliminates the need for costly large-scale laser processing or costly large-scale mechanical processing to produce the macroscopic components of the fluid structures.

[0022] Furthermore, it is proposed that the primary forming process using the ceramic material be carried out by dry pressing, injection molding (CIM), cold isostatic pressing (CIP), hot isostatic pressing (HIP), or slip casting. This advantageously allows the single-piece base body to be manufactured simply and cost-effectively. Furthermore, a particularly high strength of the base body can be achieved. Primary forming using the aforementioned processes enables significantly more cost-effective series production than the use of additive processes.

[0023] It is also proposed that a material based on aluminum oxide (Al2O3), zirconium oxide (ZrO2), silicon carbide (SiC), silicon nitride (SiSn) and / or aluminum nitride (AlN) be used as the ceramic material. This can enable advantageous shaping of the base body with the fluid structures for later post-processing. Furthermore, it is proposed that the shaping of the base body with the macroscopic fluid structures designed as media ports, depressions and / or openings takes place in a single process step during the primary shaping, wherein the base body and the macroscopic fluid structures are formed essentially simultaneously. This can enable an advantageously time-efficient and cost-effective process.

[0024] Furthermore, it is proposed that macroscopic fluidic structures designed as media ports be shaped during the primary forming process in such a way that media lines can be connected to the microfluidic component either via their inner or outer diameter. Advantageously, high functionality of the fluidic structures can be achieved during the forming process, in particular without or with a reduced number of additional post-processing steps. Preferably, the fluidic structures designed as media ports are shaped during the primary forming process in such a way that they are formed as sleeve-shaped extensions within recesses of the base body.Preferably, the fluidic structures designed as media ports are formed during the primary shaping such that the fluidic structures designed as media ports have a substantially hollow cylindrical or hollow frustoconical basic shape, which is arranged in particular substantially completely within a recess of the base body.

[0025] Furthermore, it is proposed that, in at least one method step, the base body, in particular an outer surface of the base body, is machined using a mechanical process, such as grinding and / or polishing, at least on the side on which microstructuring or the introduction of the microfluidic structures is to take place. This advantageously allows a simple creation of a connection surface for the microfluidic component.

[0026] The flatness typically achieved by mechanical post-processing of planar surfaces is usually in the range of 1 μm to 0.3 μm, with plane parallelisms of the reference surfaces between 0.2 mm and 0.05 mm. The surface roughness of the polished surfaces is typically in the range of 1 μm to 0.3 μm.

[0027] It is further proposed that during the primary shaping and / or during the introduction of the microscopic fluid structures into the base body, the thickness of the ceramic base body be reduced in a region of the base body in such a way that an increase in light transmission is achieved in that region. An advantageously high functionality of the fluid structures can be achieved during the shaping or process itself, in particular without or with a reduced number of additional post-processing steps.

[0028] Furthermore, a ceramic microfluidic component produced by the method according to the invention is proposed.

[0029] The invention is explained in more detail using exemplary embodiments.

[0030] They show:

[0031] Figure 1: a microfluidic component according to the invention for a microfluidic system produced by means of a method according to the invention, in perspective in plan view

[0032] Figure 2: the same microfluidic system in perspective from below

[0033] Figure 3: a schematic representation of an exemplary sequence of the method according to the invention for producing the microfluidic component

[0034] Figure 1 shows a perspective view of a microfluidic component for a microfluidic system produced by the method according to the invention. This microfluidic component has a base body 6 in the form of a ceramic molded part, which has been formed from a ceramic by means of primary shaping and into which macroscopic fluid structures, here in the form of openings 1 and dies 2, are introduced during the primary shaping, while filigree microscopic fluid structures, here in the form of capillary structures 3 or channels as depressions, have been subsequently introduced into a surface 6a of the base body 6 either by laser beams or by mechanical processing. The surface 6a of the base body 6 can be surface-treated (e.g.precision planarization) to reduce surface roughness, flatness, or plane parallelism to a reference surface of the surface 6a and thus improve the accuracy of the introduction of the microscopic fluid structures. However, surface processing of the surface 6a of the base body 6 after the primary shaping and before the introduction of the microscopic fluid structures is not mandatory. The ceramic is based, for example, on aluminum oxide (Al2O3), zirconium oxide (ZrO2), silicon carbide (SiC), silicon nitride (SiSn) and / or aluminum nitride (AlN).

[0035] Figure 2 shows the same microfluidic system from below, with the openings 1 located in the media ports 4. The media ports 4 are shaped during the primary forming process so that media lines can be connected to the microfluidic component via the media ports 4, either via their inner or outer diameter. The central, large-area visible die 5 partially minimizes the material thickness to increase light transmission in transparent and translucent ceramics. All structures visible in this view are incorporated into the ceramic part by primary forming.

[0036] In an advantageous embodiment, a 76 mm x 26 mm x 5 mm molded part made from dry-pressed ceramic granulate is pressed into a corresponding mold, although the invention is not limited to such dimensions. After debinding and ceramic firing, which occurs with a material-dependent shrinkage of approximately 15% to 20%, the component is precision-ground on its functional surface and then polished. Microscopic microfluidic structures are then introduced into the polished ceramic surface using laser beam ablation. Alternatively, the microscopic microfluidic structures (microscopic fluid structures) are introduced using a mechanical machining process. In a further embodiment, some of the microscopic fluid structures are introduced using a mechanical machining process, and another part of the microscopic fluid structures is introduced using laser machining.Likewise, the formation of the microscopic fluid structures is also possible by machining a section of one of the microscopic fluid structures and laser machining another section of the same microscopic fluid structures.

[0037] Dry pressing primary forming allows the production of a complex-shaped component with integrated media ports, apertures, and cavities in millimeter and centimeter sizes. This reduces the subsequent cost-intensive laser processing to the introduction of microfluidic structures in the range of a few micrometers. However, the invention is not limited to dry pressing. Primary forming can also be performed using injection molding (CIM), cold isostatic pressing (CIP), hot isostatic pressing (HIP), or slip casting, for example.

[0038] Precision machining by grinding and polishing enables the production of surfaces with flatnesses of up to 0.3 pm and surface roughnesses of less than 0.1 pm, which forms an excellent basis for the introduction of the laser structures and for subsequent covering with appropriately designed cover elements such as glass windows or additional appropriately designed microfluidic elements.

[0039] Figure 3 shows a flow chart of the corresponding process steps of a method for producing such a microfluidic component. In one process step of the method, a base body 6 of the microfluidic component to be produced is formed from a ceramic material by primary shaping. The base body 6, with the macroscopic fluid structures, is formed essentially entirely from the ceramic material in one process step. In a further process step of the method, the microscopic microfluidic structures, in particular capillary structures or channels, are introduced into the base body 6 by means of a laser processing method and / or a mechanical method.In a method step of the method, in particular before introducing the microscopic microfluidic structures, an outer surface of the base body 6, at least on the side on which microstructuring is subsequently to take place, is machined by means of a mechanical method such as grinding and / or polishing.

[0040] For applications in which an image is generated by irradiating the specimen with light, the component thickness of the base body 6 can be partially minimized in order to achieve an increase in light transmission in transparent and translucent ceramics.

[0041] List of reference symbols

[0042] 1 breakthrough

[0043] 2 die, recess

[0044] 3 Capillary structure

[0045] 4 Media port

[0046] 5 die

[0047] 6 basic bodies

[0048] 6a Outer surface

Claims

Patent claims 1. A method for producing a microfluidic component, characterized in that in a first method step, a base body (6) of the microfluidic component to be produced is formed by primary shaping, wherein the base body (6) with the at least one macroscopic fluid structure is formed substantially entirely from a ceramic material, and that in a further method step, microscopic fluid structures are introduced into the base body (6) by means of a laser processing method and / or by means of a mechanical processing method.

2. Method according to claim 1, characterized in that the primary shaping using the ceramic material is carried out by dry pressing, injection molding (CIM), cold isostatic pressing (CIP), hot isostatic pressing (HIP) or slip casting.

3. Method according to claim 1 or 2, characterized in that a material based on aluminum oxide (Al2O3), zirconium oxide (ZrO2), silicon carbide (SiC), silicon nitride (SiSiU) and / or aluminum nitride (AlN) is used as the ceramic material.

4. Method according to one of the preceding claims, characterized in that the macroscopic fluid structures are media ports (4), depressions (2, 5) and / or openings (1) and / or that the microscopic fluid structures are capillary structures (3) or channels.

5. The method according to claim 4, characterized in that the shaping of the base body with the macroscopic fluid structures designed as media ports (4), depressions (2, 5) and / or openings (1) takes place in a single process step during the primary shaping, wherein the base body (6) and the macroscopic fluid structures are formed substantially simultaneously.

6. Method according to claim 4 or 5, characterized in that the macroscopic fluidic structures designed as media ports (4) are formed during the primary shaping in such a way be shaped so that media lines can be connected to the microfluidic component either via their inner or outer diameter.

7. Method according to one of the preceding claims, characterized in that in at least one method step the base body (6), in particular an outer surface (6a) of the base body (6), at least on the side on which the microscopic fluid structures are subsequently to be introduced, is machined by means of a mechanical method, such as grinding and / or polishing.

8. Method according to one of the preceding claims, characterized in that during the primary shaping and / or during the introduction of the microscopic fluid structures into the base body (6), a thickness of the ceramic base body (6) is reduced in a region of the base body (6) in such a way that an increase in the light transmission in the region is achieved.

9. A ceramic microfluidic component manufactured by a method according to any one of the preceding claims.

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